Datasets:
InMedData
/
Cardio_v1

Dataset card Data Studio Files Community
1
Unnamed: 0
int64
0
2.34M
title
stringlengths
5
21.5M
abst
stringlengths
1
21.5M
1,800
Adverse effects of direct current cardioversion on cardiac pacemakers and electrodes Is external cardioversion contraindicated in patients with permanent pacing systems?
Use of pacing in sick sinus syndrome and recent developments in pacemaker therapy for intermittent atrial fibrillation raise the question of whether external electrical cardioversion should be used for termination of atrial fibrillation. This paper analyzes three cases of pacemaker and/or electrode dysfunction appearing after direct current (DC) cardioversion for termination of atrial fibrillation. Despite similar conditions during cardioversion in all cases, different dysfunctions reflecting damage to the pulse generator and/or a rise of the stimulation threshold in both, atrial and ventricular leads, have been observed. The possible mechanisms for these effects are discussed and recommendations for the management of cardioversion in patients with permanent pacemaker systems are given.
1,801
Electrical storm in Brugada syndrome successfully treated using isoprenaline.
A case of an electrical storm occurring in a patient implanted with a cardioverter-defibrillator for Brugada syndrome is reported. Recurrent ventricular fibrillation was initiated by short-coupled isolated monomorphic ventricular premature beats probably originating from the right ventricular outflow tract, associated with a manifest electrocardiographic pattern of Brugada syndrome. Infusion of atropine accelerated the heart rate but did not prevent ventricular fibrillation, however, low doses of isoprenaline quickly obviated any recurrence of ventricular fibrillation. This was associated with the disappearance of the short-coupled premature beats together with a normalization of the electrocardiographic pattern. Possible mechanisms are discussed according to the accepted pathophysiological hypothesis.
1,802
Hibernating myocardium: chronically adapted to ischemia but vulnerable to sudden death.
The inability to reproduce spontaneous ventricular fibrillation in an animal model of chronic coronary artery disease has limited advances in understanding mechanisms of sudden cardiac death (SCD). Swine with hibernating myocardium arising from a chronic left anterior descending coronary artery (LAD) occlusion have a high rate of SCD that parallels the poor clinical survival of medically treated patients with hibernating myocardium. Kaplan-Meier analysis (n=426) demonstrated a cumulative mortality of 49% after 5 months that was almost entirely attributable to spontaneous SCD. Using implantable loop recorders, ventricular fibrillation was documented as the arrhythmic mechanism of death in all animals (n=10) and was usually preceded by ventricular tachycardia (n=8). Physiological studies before SCD (n=7) demonstrated total LAD occlusion and collateral-dependent myocardium (n=5), excluding acute occlusion as a major trigger of arrhythmia. The physiological substrate of hibernating myocardium was present before SCD, with reductions in LAD perfusion (SCD 0.79+/-0.13 versus 0.80+/-0.08 mL/min per g) and wall thickening (SCD 28+/-3% versus 22+/-3%) that were similar to survivors (n=14). Triphenyltetrazolium chloride infarcts among animals with SCD were infrequent (4 of 32) and small, averaging 4.6% of LV mass. Histology (n=4) showed postmortem changes but no acute inflammation nor contraction band necrosis. These data support the notion that hibernating myocardium is a pathophysiological substrate at high risk of SCD. This is independent of changes in functional stenosis severity, acute myocardial necrosis, or fibrotic scar. Thus, regional adaptations that promote myocyte survival in the setting of chronic repetitive ischemia result in a substrate with enhanced vulnerability to lethal arrhythmias and SCD.
1,803
Atrial demand pacemakers in sick sinus syndrome: an efficient and reliable approach in selected patients.
Atrial demand pacemakers offer the advantages of lower cost and less cumbersome implantation in selected sick sinus syndrome patients with acceptable atrioventricular (AV) conduction. However, concerns about their long-term performance and AV conduction degeneration still worry certain implantation physicians. There were still limited long-term follow-up data of atrial demand pacemakers, especially in oriental people. Thus, we reviewed our long-term follow-up results.</AbstractText>From January 1996 to December 1998, all symptomatic sick sinus syndrome patients with atrial demand pacemaker (AAI, AAIR) treatment were retrospectively studied. They were all regularly followed up at our pacemaker clinic. The patients' clinical presentations, coronary angiography, electrophysiology results and their initial implantation parameters were collected. All outpatient follow-up histories, electrocardiogram (EKG) rhythm strips, and chronic threshold test data were also retrieved.</AbstractText>There were 51 patients enrolled in this study, with a mean age of 68 +/- 7 years. The average follow-up duration was 44 +/- 17 months. The baseline His bundle-ventricular (HV) interval was 40 +/- 6 ms and AV 1:1 conduction cycle lengths were up to 388 +/- 65 ms. Two patients (2/51, 3.9%) had acute lead dislodgement within three days and needed reimplantation. During the long-term follow-up, all patients maintained good pacing function. Five patients (5/51, 9.8%) had occasions of sensing failure, as detected by 12-lead surface EKG or Holter monitor, which all resolved after reprogramming of the sensing threshold. Only 1 patient ( 1/51, 1.9%) developed Wenckebach AV block in the daytime as shown by EKG and was later upgraded to a DDDR pacemaker uneventfully. No patient became victim of chronic atrial fibrillation during the long-term follow-up.</AbstractText>Our follow-up study again suggests that atrial demand pacemakers have good initial implantation and long-term results. The chance of developing AV conduction degeneration during follow-up is quite low (1.9%, average annual incidence 0.5%). AAI and AAIR pacemakers are a reliable and physiological approach to selected sick sinus syndrome patients and should be the pacemaker of choice in suitable cases.</AbstractText>
1,804
[Effect of daidzein on antiarrhythmia].
To study the effect of Daidzein on Antiarrhythmia.</AbstractText>The conventional antiarrhythmia methods were used.</AbstractText>Daidzein was remarkedly effective in preventing ventricular fibrillation induced by chloroform in mice and arrhythmia induced by aconitine in rats. The arrhythmia induced by adrenalin in rabbits was antagonized by Daidzein and it could obviously inhibit the action potential amplitude of isolated sciatic nerves in toads. And it could also prevent ventricular fibrillation induced by calcium chloride in rats, and obviously reduce the death rate of rats. Its anti-arrhythmic effect was dose-dependent.</AbstractText>Daidzein has obvious protective effect on drug-induced arrhythmia, which may be related to its inhibition of Na+ or Ca2+ influx and its blocking beta-adrenergic receptor.</AbstractText>
1,805
The impact of atrial prevention and termination therapies on atrial tachyarrhythmia burden in patients receiving a dual-chamber defibrillator for ventricular arrhythmias.
This prospective, multicenter, randomized trial evaluated the effects of atrial prevention and termination therapies on atrial tachyarrhythmia (ATA) burden in patients with a standard indication for an implantable cardioverter defibrillator (ICD).</AbstractText>A Jewel AF or GEM III AT ICD was implanted in 451 patients. At 1-month post-implant, patients were randomized to atrial prevention and termination therapies ON ( n = 199) or OFF ( n = 206) and followed for 6 additional months. Automatic atrial shocks were enabled in only 14% of the ON group. The follow-up time after randomization was 6.9 +/- 2.4 months ON versus 6.8 +/- 2.3 months OFF.</AbstractText>There were 126/405 (31.1%) patients who had AT/AF episodes during follow-up. Only four patients received a shock to treat ATA's during follow-up. The median ATA burden was 0 hours/month in both the ON and OFF groups ( P = 0.40). The mean ATA burden was 4.3 +/- 20.0 hours/month ON versus 9.0 +/- 50.0 hours/month OFF ( P = 0.11). In a subgroup of 192 patients with a history of ATA's, the median burden was 0 hours/month in the both groups ( P = 0.23). However, the mean burden in this subgroup was 7.6 +/- 27.1 hours/month ON versus 19.2 +/- 73.7 hours/month OFF ( P = 0.056).</AbstractText>In patients receiving an ICD for ventricular arrhythmias, no significant change in ATA burden was observed when atrial prevention and termination therapies were enabled. This may have been due to the low ATA burden in this population. In a subgroup of patients with history of ATA's, there was a trend towards a reduction in mean burden.</AbstractText>
1,806
Racial variation in the prevalence of atrial fibrillation among patients with heart failure: the Epidemiology, Practice, Outcomes, and Costs of Heart Failure (EPOCH) study.
This study was designed to determine the association between race and atrial fibrillation (AF) among patients with heart failure (HF).</AbstractText>Atrial fibrillation is known to complicate HF, but whether its prevalence varies by race, and the reasons why, are not well understood.</AbstractText>We identified adults hospitalized with confirmed HF within a large integrated healthcare delivery system. We obtained information on demographics, comorbidity, vital signs, medications, and left ventricular systolic function status. "Atrial fibrillation" was defined as AF or atrial flutter documented by electrocardiogram or prior physician-assigned diagnoses. We evaluated the independent relationship between race and AF using multivariable logistic regression.</AbstractText>Among 1,373 HF patients (223 African Americans, 1,150 Caucasians), the prevalence of AF was 36.9% (95% confidence interval [CI] 34.3% to 39.5%). Compared with Caucasians, African Americans were younger (mean age 67 vs. 74 years, p &lt; 0.001) and more likely to have hypertension (86.6% vs. 77.7%, p &lt; 0.01) and prior diagnosed HF (79.4% vs. 70.7%, p &lt; 0.01). African Americans had less prior diagnosed coronary disease, revascularization, hypothyroidism, or valve replacement. Atrial fibrillation was much less prevalent in African Americans (19.7%) than Caucasians (38.3%, p &lt; 0.001). After adjustment for risk factors for AF and other potential confounders, African Americans had 49% lower odds of AF (adjusted odds ratio 0.51, 95% CI 0.35 to 0.76).</AbstractText>In a contemporary HF cohort, AF was significantly less common among African Americans than among Caucasians. This variation was not explained by differences in traditional risk factors for AF, HF etiology and severity, and treatment.</AbstractText>
1,807
Detection of myocardial injury after internal cardioversion for atrial fibrillation.
Cardiac troponin levels do not rise to marked levels after external cardioversion of atrial fibrillation. Subsequent test discharges during implantation of cardioverter defibrillators may cause an elevation of cardiac troponin levels, but are still controversial.</AbstractText>To determine whether the biomarkers of cardiac injury increase after internal cardioversion (IC) of atrial fibrillation.</AbstractText>Forty-four patients with chronic atrial fibrillation were studied (mean age 59 +/-7 years). Electrode catheters were inserted through the femoral vein. One of these was positioned in the lower right atrium. A second defibrillation electrode was placed in the coronary sinus and an additional catheter was positioned in the right ventricular apex in order to obtain satisfactory R wave synchronization and to provide postshock ventricular pacing. The shocks were delivered by external defibrillator. Starting with a test shock of 1 J intensity, the energy was increased in steps (to maximum 15 J) until cardioversion was achieved. At least 1 min was permitted to elapse between unsuccessful defibrillation attempts before the next shock was applied. Blood samples for serum levels of cardiac troponin T, cardiac troponin I, creatine kinase MB and myoglobin were drawn before and 2 h, 4 h, 8 h and 24 h after IC. Each level of biomarker was compared with baseline.</AbstractText>In 40 of 44 patients, IC was successful at a mean cardioversion threshold of 7.6+/-3.3 J. Although the serum levels of these biomarkers tended to rise, marked elevation was not detected in any of samples (P&gt;0.05 for each). There was no correlation between the levels of biomarkers and the number and energy of shocks applied. No severe complications were observed.</AbstractText>Following uncomplicated IC of atrial fibrillation, cardiac biomarkers do not rise to marked levels, which indicates that significant myocardial injury does not occur by shocks in the usual dosage.</AbstractText>
1,808
Inappropriate ICD therapy due to proarrhythmic ICD shocks and hyperpolarization.
A 50-year-old man with an ischemic cardiomyopathy underwent ICD implantation for inducible ventricular fibrillation (VF). Sixteen months later he experienced inappropriate ICD therapy due to atrial fibrillation with a rapid ventricular response. The initial shock resulted in the initiation of VF (proarrhythmia) and the patient received an additional shock converting his rhythm to an idioventricular rhythm with a cycle length of 490 ms (122 beats/min). Due to lead hyperpolarization, the device oversensed ventricular events and the patient subsequently received additional shocks.
1,809
Arrhythmogenic right ventricular cardiomyopathy with left ventricular involvement and aortic dissection.
Ten years ago, a 59-year-old patient presented with ventricular fibrillations. The resting ECG showed findings typical for ARVC. Echocardiography and ventriculography confirmed the diagnosis of ARVC showing a dilated right ventricle with aneurysms. MRI showed additional fatty replacement of the LV. Furthermore, the diagnosis of a chronic aortic dissection was established. Two years after ICD implantation, the patient died of progressive right heart failure. On autopsy, most of the RV and parts of the LV were replaced by fatty tissue, and the media of the aorta showed degenerative changes. A pathogenetic link between the two diseases remains speculative at this time.
1,810
Ventricular rate control during atrial fibrillation and AV node modifications: past, present, and future.
Atrial fibrillation (AF) is the most common arrhythmia. Currently there are two broad strategic treatment options for AF: rhythm control and rate control. For rhythm control, the treatment is directed toward restoring and maintaining the sinus rhythm. For rate control, the intention is to slow ventricular rate while allowing AF to continue. In both cases anticoagulation therapy is recommended. The results of currently available clinical trials demonstrated clearly that rate control is not inferior to rhythm control. Thus, rate control is an acceptable primary therapy for many AF patients. The rate control can be achieved essentially by depressing or modifying the filtering properties of the atrioventricular (AV) node. This can be attained by medications that depress the impulse transmission within the AV node, by anatomic modification of the AV communications, as well as by autonomic manipulations that produce AV node negative dromotropic effect. We are reviewing current clinical and newer experimental modalities aimed at enhancing the lifesaving function of this remarkable nodal structure.
1,811
Feasibility of implantable cardioverter defibrillator use in elderly patients: a case series of octogenarians.
This article addresses the feasibility and safety of ICD therapy in patients &gt;80 years of age. Recent trials have expanded the indication for ICD implantation to include an increasing number and variety of patients. The feasibility of ICD implantation in elderly patients has not been adequately studied. A prospectively collected single center ICD database was analyzed to assess the safety and feasibility of ICD implantation in elderly patients. Patients were divided based on age into two groups (group 1: 70-79 years of age, n = 183; group 2: &gt;or=80 years of age, n = 29). The two groups were similar in gender distribution, NYHA class, and indication for implantation. The actuarial survival was not significantly different between groups 1 and 2 (P &gt; 0.05; primary endpoint), with a 1-year survival of 91% and 93% in groups 1 and 2, respectively, (P = NS). The complication rates at the time of ICD implantation were similar in groups 1 and 2 (6.6% and 13.1%, respectively, P = 0.16). Age alone may not be sufficient criteria to exclude ICD implantation. The current consensus guidelines for ICD implantation appear to be generalizable to treating octogenarians who are otherwise medically fit.
1,812
Effects of pretreatment with intravenous flecainide on efficacy of external cardioversion of persistent atrial fibrillation.
Electrical cardioversion is the most effective and safe method to restore sinus rhythm in patients with persistent AF. However, at least 25% of electrical cardioversions are unsuccessful. The aim of the present study was to evaluate, in a prospective, randomized and double-blind study, the efficacy of a pretreatment with intravenous flecainide in patients who underwent electrical cardioversion. Fifty-four consecutive patients with persistent AF, mean arrhythmia duration 8 (mean 3-18) weeks, were randomized in two groups. In the first group (n = 26), patients received flecainide (2 mg/kg as a 30-minute IV infusion) before electrical cardioversion. In the second group (n = 28), 100 mL IV infusion of 5% glucose was administered 30 minutes before electrical cardioversion. The study evaluated the (1). acute efficacy of electrical cardioversion, (2). mean and maximal energy required, (3). mean number of shocks needed, and (4). incidence of complications. The two groups were similar in terms of age, sex, mean AF duration, left ventricular systolic function, atrial dimension, and cardiovascular risk factors. Seventy-seven percent of patients recovered sinus rhythm with electrical cardioversion. No statistical difference was noted between the two groups: flecainide 19/26 (73%) versus placebo 23/28 (82%). No significant differences were found concerning mean or maximal energy and number of shocks required. No major complications were observed. After a 30-day follow-up, 54% of patients maintained sinus rhythm with no difference between the two groups. Pretreatment with intravenous flecainide before electrical cardioversion is not useful in reducing technical failure of cardioversion, however, flecainide does not diminish the effectiveness of electrical cardioversion.
1,813
Incidence of postdischarge symptomatic paroxysmal atrial fibrillation in patients who underwent coronary artery bypass graft: long-term follow-up.
The aim of this retrospective study was to determine the incidence of symptomatic AF of patients who had undergone coronary artery bypass grafting (CABG) during long-term follow-up. The study population included 305 post-CABG patients who were regularly followed in the outpatient clinic. Paroxysmal AF (PAF) was defined as an episode of symptomatic AF when symptoms were prolonged enough for the patient to request medical care. Perioperative AF occurred in 88 (28.9%) patients. Postdischarge symptomatic PAF occurred in 25 (8.2%) patients with an annual incidence of 2% during a mean follow-up of 48 +/- 30 months. Eighteen (20.4%) patients also experienced perioperative AF with an annual incidence of 5.1%, while only 7 (3.2%) of 217 patients, without perioperative AF, had postdischarge AF (P &lt; 0.0003). During long-term follow-up, postdischarge AF has a low incidence and prophylactic antiarrhythmic therapy is not recommended. The method of follow-up and retrospective analysis may understate PAF and even miss some symptomatic episodes. Perioperative AF is a predictor of symptomatic late PAF recurrences, particularly in patients with reduced left ventricular function.
1,814
Development of atrial fibrillation in patients with atrioventricular block after atrioventricular synchronized pacing.
Many studies have evidenced an increased incidence of AF in patients receiving single chamber ventricular pacing (VVI) when compared with those undergoing an atrial-based system (AAI or DDD). However, the difference in incidence of AF between two atrial-based systems (VDD, DDD) in patients with AV block was still controversial. This study was conducted to compare the development of AF between different modes of pacemakers (VDD and DDD) in patients with symptomatic AV block. A retrospective review was conducted of the detailed records of all consecutive patients who received permanent pacemakers due to symptomatic bradycardia from March 1995 to March 2000. The occurrence of AF was documented when there was presence of AF in the free-run or 12-lead ECG, any ECG strips, or persistent AF on 24-hour Holter ECG during the follow-up. The study included 152 patients (44 women, 108 men; mean age 73). The patients were divided into two groups: VDD (n = 100) and DDD (n = 52). The mean follow-up was 48.9 +/- 22.9 months. The incidence of AF was 7.9%. A higher incidence of AF was noted in the DDD group (15.4%) when compared with the VDD group (4.0%, P = 0.023). The incidence of development of AF in patients with AV block was higher in those receiving DDD cardiac pacing when compared with those who received the VDD system. The authors suggest that VDD pacing may be a better choice than the DDD system for patients with AV block, but without clinical evidence of sinus node dysfunction, and if an atrial lead is required, it should be placed close to the Bachmann's bundle.
1,815
Application of radiofrequency energy in surgical and interventional procedures: are there interactions with ICDs?
During surgical and interventional procedures, interference may occur between ICDs and electrical cautery or with the application of RF energy. This may lead to the false induction of ICD therapies or could even result in device malfunction, which represents a potential perioperative hazard for the patient. This study analyzed the intraoperative interactions in 45 consecutive ICD patients in reference to different surgical and interventional procedures. A total of 33 surgical operations (general surgery [n = 14], urologic [n = 5], abdominal [n = 10], gynecological [n = 2], thoracic [n = 1], neurosurgical [n = 1]) and 12 interventional therapies (RF catheter ablation [n = 10], endoscopic papillotomy [n = 2]) were performed. The ICD devices were all located in left pectoral position and consisted of 25 single and 20 dual chamber defibrillators. During the procedure, tachyarrhythmia detection (VF 296 +/- 20 ms, VT 376 +/- 49 ms) of the devices was maintained active (monitoring mode), only ICD therapies were inactivated. The indifferent electrode of the electrical cauter/RF generator was placed in standard positions (right/left mid-femoral position [n = 27/8], thoracic spine area [n = 10]). After the procedure, the ICD memory was checked for detections and for changes in the programming. There was no oversensing, reprogramming, or damage of any defibrillator caused by RF energy. Despite the lack of undesired interactions, ICDs should be inactivated preoperatively to assure maximum patient safety. However, should inactivation not be possible, or the achievement uncertain, electromagnetic interference is highly unlikely.
1,816
Influence of age on atrial fibrillation inducibility.
The prevalence of AF is known to increase in the elderly. Some electrophysiological changes were reported in these patients, but the effects of age on AF inducibility and other electrophysiological signs associated with atrial vulnerability are unknown. The purpose of the study was to evaluate the effects of age on atrial vulnerability and AF induction. The study consisted of 734 patients (age 16-85 years, mean 61 +/- 15 years) without spontaneous AF who were admitted for electrophysiological study. Study was indicated for dizziness or ventricular tachyarrhythmia. Programmed atrial stimulation was systematically performed. One and two extrastimuli were delivered in sinus rhythm and atrial driven rhythms (600, 400 ms). Univariate and multivariate analysis of several clinical and electrophysiological data were performed. AF inducibility, defined as the induction of an AF lasting &gt; 1 minute, was paradoxically and significantly decreased in elderly (&gt; 70 years) patients compared to younger patients (&lt; 70 years) (P &lt; 0.01). AF inducibility was present in 40% of 62 patients &lt; 40 years, 39% of 99 patients age 40-50 years, 37% of 130 patients age 50-60 years, 38% of 222 patients age 60-70 years, and only 28% of 221 patients &gt; 70 years. There was no significant correlation with the sex, the presence of dizziness, the presence or not of an underlying heart disease, the left ventricular ejection fraction, and the presence of salvos of atrial premature beats on 24-hour Holter monitoring. There was a significant correlation with a longer atrial effective refractory period in the elderly (226 +/- 41 ms) than in younger patients (208 +/- 31 ms) (P &lt; 0.001). Other electrophysiological parameters of atrial vulnerability did not change significantly. Increased atrial refractory period and age &gt;70 years were independent factors of decreased AF inducibility. Programmed atrial stimulation should be interpreted cautiously before the age of 70 years. AF induction is facilitated by the presence of a short atrial refractory period in these patients. Surprisingly, AF inducibility decreases in patients &gt; 70 years because their atrial refractory period increases. Therefore, increased AF prevalence in these patients should be explained by nonelectrophysiological causes.
1,817
[Risk assessment in acute myocardial infarction].
Despite the appearance in clinical practice of modern treatment modes as thrombolysis and percutaneous coronary intervention, in-hospital mortality from acute myocardial infarction remains an important problem. In this paper we review recently published data concerning risk stratification in the acute phase of myocardial infarction, different factors affecting the prognosis, their dynamics in the course of the disease, and inter-factor relations. We emphasize the prognostic value of three factors: heart rate variability, left ventricular dysfunction and arrhythmias. Changes in heart rate variability are discussed in association to location of myocardial infarction, patency of infarct-related artery, the chosen treatment mode and its timing. Left ventricular diastolic function and right ventricular function are shown to be predictors of morbidity and mortality after myocardial infarction besides left ventricular systolic function. We also present the latest data concerning the prognostic implication of arrhythmias, their relation to left ventricular function and autonomic nervous system balance. Atrial fibrillation and atrial flutter appear to be important factors in predicting mortality after myocardial infarction, especially in the elderly, as well as ventricular arrhythmias - sustained ventricular tachycardia and ventricular fibrillation.
1,818
Relationships between sinus rhythm, treatment, and survival in the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) Study.
The AFFIRM Study showed that treatment of patients with atrial fibrillation and a high risk for stroke or death with a rhythm-control strategy offered no survival advantage over a rate-control strategy in an intention-to-treat analysis. This article reports an "on-treatment" analysis of the relationship of survival to cardiac rhythm and treatment as they changed over time.</AbstractText>Modeling techniques were used to determine the relationships among survival, baseline clinical variables, and time-dependent variables. The following baseline variables were significantly associated with an increased risk of death: increasing age, coronary artery disease, congestive heart failure, diabetes, stroke or transient ischemic attack, smoking, left ventricular dysfunction, and mitral regurgitation. Among the time-dependent variables, the presence of sinus rhythm (SR) was associated with a lower risk of death, as was warfarin use. Antiarrhythmic drugs (AADs) were associated with increased mortality only after adjustment for the presence of SR. Consistent with the original intention-to-treat analysis, AADs were no longer associated with mortality when SR was removed from the model.</AbstractText>Warfarin use improves survival. SR is either an important determinant of survival or a marker for other factors associated with survival that were not recorded, determined, or included in the survival model. Currently available AADs are not associated with improved survival, which suggests that any beneficial antiarrhythmic effects of AADs are offset by their adverse effects. If an effective method for maintaining SR with fewer adverse effects were available, it might be beneficial.</AbstractText>
1,819
Implantable cardioverter/defibrillator therapy in arrhythmogenic right ventricular cardiomyopathy: single-center experience of long-term follow-up and complications in 60 patients.
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of ventricular tachycardia (VT) and cardiac arrest in young patients. We hypothesized that treatment with implantable cardioverter/defibrillators (ICDs) is safe and improves the long-term prognosis of ARVC patients at high risk of sudden death.</AbstractText>Sixty patients with ARVC (aged 43+/-16 years) were treated with transvenous ICD systems. Despite a higher number of right ventricular sites tested for adequate lead positions (P&lt;0.05), lower R-wave amplitudes (P&lt;0.001) were achieved in ARVC patients compared with other entities. During follow-up of 80+/-43 months (396 patient-years), event-free survival was 49%, 30%, 26%, and 26% for appropriate ICD therapies and 79%, 64%, 59%, and 56% for potentially fatal VT (&gt;240 bpm) after 1, 3, 5, and 7 years, respectively. Multivariate analysis identified extensive right ventricular dysfunction as an independent predictor of appropriate ICD discharge. Fifty-three adverse events occurred in 37 patients during the perioperative (n=10) or follow-up (n=43) period, mainly related to the leads (n=31 in 21 patients). No lead perforation was observed. Freedom from adverse events was 90%, 78%, 56%, and 42% and freedom from lead-related complications was 95%, 85%, 74%, and 63% after 1, 3, 5, and 7 years, respectively.</AbstractText>These results strongly suggest an improvement in long-term prognosis by ICD therapy in high-risk patients with ARVC. However, meticulous placement and long-term observation of transvenous lead performance with focus on sensing function are required for the prevention and/or early recognition of disease progression and lead-related morbidity during long-term follow-up of ICD therapy in ARVC.</AbstractText>
1,820
Initiation and monitoring of class III antiarrhythmic agents.
Initiation and Monitoring of Class III Agents. Dofetilide is a Class III antiarrhythmic agent that is approved by the United States Food and Drug Administration (FDA) for use in the conversion of atrial fibrillation, as well as in the maintenance of normal sinus rhythm. Because of the risk of torsades de pointes associated with dofetilide, the FDA mandated in-hospital initiation of therapy and initially restricted dofetilide's availability to institutions and prescribers who completed appropriate educational forums. The use of dofetilide within health care systems requires specific procedures for prescribing, dispensing, and monitoring, as well as a format for educating personnel who will be involved in the care of these patients. Several models have demonstrated success in initiating dofetilide and are also used for sotalol, which also can cause torsades de pointes. The utilization of nonphysician personnel, such as nurse practitioners and clinical pharmacists, in conjunction with a team approach were essential components for the success of these models. Preprinted order forms or procedural guidelines, as well as computer-assisted dosing programs, can be utilized to prevent inappropriate or miscalculated dosing of these agents, which potentially can cause life-threatening ventricular arrhythmias.
1,821
Clinical experience with dofetilide in the treatment of patients with atrial fibrillation.
Dofetilide for Treatment of AF.</AbstractText>Dofetilide is the newest drug approved by the United States Food and Drug Administration for the treatment of patients with atrial fibrillation (AF). Few data on the efficacy and safety of dofetilide in a diverse group of patients are available. The aim of this study was to evaluate the results of dofetilide in a consecutive series of 69 patients with AF.</AbstractText>Sixty-nine patients with persistent (n = 53) or paroxysmal (n = 16) AF were administered dofetilide in-hospital. Prior to starting dofetilide, all patients had been adequately anticoagulated, and concomitant agents contraindicated in the presence of dofetilide were discontinued. Heart rhythms were monitored continuously by telemetry in all patients. The initial dose, which was determined using the Cockroft-Gault calculated creatinine clearance, was 500 microg bid, 250 microg bid, and 125 microg bid in 51, 13, and 5 patients, respectively. Reductions in subsequent dosage occurred in 12 patients, 4 for QT prolongation. Dofetilide was discontinued in-hospital in 7 patients, 2 for adverse arrhythmic events and 3 for unacceptable QT prolongation. Twenty-seven (63%) of 43 patients in AF converted spontaneously to sinus rhythm. Fifty-eight patients were discharged receiving dofetilide treatment and were followed as outpatients for 21 +/- 7 months. One third of patients continued to take dofetilide at 1 year. One patient had a cardiac arrest 1 day after hospital discharge.</AbstractText>Dofetilide is a well-tolerated antiarrhythmic drug with a high conversion rate of AF to sinus rhythm. One third of patients maintained sinus rhythm at 1 year. Proarrhythmia can occur and initiation of therapy must be performed in-hospital.</AbstractText>
1,822
Atrial fibrillation in heart failure: prognostic significance and management.
AF in Heart Failure. Atrial fibrillation and congestive heart failure are commonly occurring cardiac disorders that often exist concomitantly. The prognostic significance of the presence or absence of atrial fibrillation, as an independent risk factor, in patients with heart failure remains controversial. Antiarrhythmic drugs with good hemodynamic profiles and neutral effects on survival are preferred treatments for converting atrial fibrillation and maintaining sinus rhythm. Other standard therapies for congestive heart failure, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and beta-blockers also have a role in the treatment of these coexisting disease states. The article presents an overview of atrial fibrillation in patients with heart failure and reviews the prevalence, prognostic significance, and efficacy of various antiarrhythmic agents for the conversion and maintenance of sinus rhythm.
1,823
A surgical case of combined valvular disease complicated by absent right superior vena cava and persistent left superior vena cava.
A 74-year-old man with combined valvular disease with a recent cerebral infarction was admitted. While undergoing thorough examination for valvular disease, absent right superior vena cava (RSVC) and persistent left superior vena cava (PLSVC) were recognized. Chest X-ray film suggested a right arch protrusion, and CT and venogram confirmed the diagnosis. During surgery, replacement of the mitral and aortic valves and annuloplasty of the tricuspid valve were performed. A blood draining cannula was inserted in retrograde fashion from the coronary sinus into the PLSVC, without any difficulties in the tricuspid valve repair. Due to bradycardic atrial fibrillation, we believed that it would be difficult to insert an endocardial electrode postoperatively, hence myocardial electrode was placed in the right ventricular wall. Absent RSVC combined with PLSVC is very rare, and a patient who underwent combined valve surgery with this rare anatomical abnormality is herein presented.
1,824
Experimental evaluation of the influence of complete artificial circulation on renal circulation and tissue metabolism -comparative study of pulsatile vs nonpulsatile circulation.
In this study, pulsatile and nonpulsatile assisted circulation were compared to evaluate renal circulation under complete artificial circulation. In addition, differences were also compared between animals supported by high (assist rate 80%)- and low (assist rate 60%)-level artificial circulation. Using 20 pigs, ventricular fibrillation was induced after cardiogenic shock, assist by mechanical support by pulsatile and nonpulsatile artificial circulation. Hemodynamics and renal circulation were evaluated by measuring renal arterial blood flow, renal cortical blood flow, renal medullar blood flow, cortical/medullar flow ratio, serum urea nitrogen levels, blood creatinine levels, urinary beta(2)-microglobulin (MG) levels, and serum beta(2)-MG levels. Tissue metabolism was evaluated by comparing arterial ketone body ratios and lactic acid/pyruvic acid ratios. During the acute stage of cardiogenic shock, redistribution of renal blood flow and tissue metabolism were improved in the pigs with pulsatile artificial circulation, suggesting the usefulness of pulse pressure. In nonpulsatile artificial circulation, the possibility of irreversible renal dysfunction was suggested. Although changes in renal blood flow were smaller in high-level artificial circulation than in low-level artificial circulation, physiological maintenance of renal circulation was better in pulsatile artificial circulation than in nonpulsatile artificial circulation. These results suggest that this effect of pulsatile assisted circulation may become more marked when evaluated in the early state after cardiogenic shock.
1,825
Effect of beta-adrenergic blockade on dynamic electrical restitution in vivo.
The slope of the action potential duration (APD) restitution curve may be a significant determinant of the propensity to develop ventricular fibrillation, with steeper slopes associated with a more arrhythmogenic substrate. We hypothesized that one mechanism by which beta-blockers reduce sudden cardiac death is by flattening the APD restitution curve. Therefore, we investigated whether infusion of esmolol modulates the APD restitution curve in vivo. In 10 Yorkshire pigs, dynamic APD restitution curves were determined from measurements of APD at 90% repolarization with a monophasic action potential catheter positioned against the right ventricular septum during right ventricular apical pacing in the basal state and during infusion of esmolol. APD restitution curves were fitted to the three-parameter (a, b, c) exponential equation, APD = a.[1 - e((-b.DI))] + c, where DI is the diastolic interval. Esmolol decreased the maximal APD slope, 0.68 +/- 0.14 vs. 0.94 +/- 0.24 (baseline), P = 0.002, and flattened the APD restitution curve at shorter DIs, 75 and 100 ms (P &lt; 0.05). To compare the slopes of the APD restitution curves at similar steady states, slopes were also computed at points of intersection between the restitution curve and the lines representing pacing at a fixed cycle length (CL) of 200, 225, 250, 275, and 300 ms using the relationship CL = APD + DI. Esmolol decreased APD restitution slopes at CLs 200-275 ms (P &lt; 0.05). Esmolol flattens the cardiac APD restitution curve in vivo, particularly at shorter CLs and DIs. This may represent a novel mechanism by which beta-blockers prevent sudden cardiac death.
1,826
Is arterial stiffness a contributing factor to atrial fibrillation in patients with hypertension? A preliminary investigation.
Atrial fibrillation (AF) is the most common tachyarrhythmia encountered by clinicians. When AF occurs in patients with structural disorders, hypertension is most common. Hypertension may provoke or enable AF to occur through several mechanisms. One could be the resultant effects of increased afterload on the left ventricle and consequent changes in the left atrium. The latter could be the direct linear effect of elevated diastolic atrial pressure and its proximate effect on atrial electrophysiology. Alternatively, it may be a more indirect and complex relationship involving chronic morphologic, electrophysiologic, and secretory consequences in the atrium consequent to a chronically reduced left ventricular (LV) compliance.</AbstractText>To assess this relationship, the arterial stiffness index (ASI) was determined in 53 hypertensive patients (29 with AF, 24 without) and 17 nonhypertensive controls with AF and its relationship to ventricular hypertrophy and AF was determined. All except 5 patients with AF had paroxysmal AF (PAF); the other 5 were in sinus rhythm status after cardioversion of a persistent AF episode.</AbstractText>The ASI was significantly higher in patients with hypertension, both with and without AF than in lone AF patients, but did not distinguish between hypertensives with and without AF. The ASI was higher in the presence of LV hypertrophy (LVH).</AbstractText>The ASI and LVH cannot be used to predict the risk of AF in hypertensive patients and the development of AF in hypertensives is more complex than just that of the immediate effect of elevated ventricular pressure on atrial pressure and stretch. Rather, AF is linked through the chronic alterations that are consequent to atrial hypertension.</AbstractText>
1,827
Use of ibutilide for cardioversion of recent-onset atrial fibrillation and flutter in elderly.
Ibutilide is a class III antiarrhythmic drug used for pharmacological cardioversion of recent-onset atrial fibrillation and flutter. The objective of the study was to assess the efficacy of ibutilide in elderly patients (age, &gt;or=65 years). The study population consisted of 32 consecutive elderly patients (17 women, 15 men; mean age, 76 +/- 8 years; age range, 65-94 years) with recent-onset atrial fibrillation (19 patients) or flutter (13 patients). Ibutilide was administered 1-mg intravenously over 10 minutes, and a second 10-minute infusion of 1-mg was given if the arrhythmia did not terminate within 10 minutes after the end of initial infusion. Twenty-six patients received two 1-mg doses of ibutilide. The rate of successful arrhythmia termination was 59% (19 patients): 63% in patients with atrial fibrillation (12 of 19) and 54% in atrial flutter (7 of 12). The mean conversion time was 33 +/- 45 minutes. Three-fourths of the conversions occurred within 45 minutes of treatment. No clinical variables were correlated with success of cardioversion. Patients with a left atrial size of 50 mm or larger had a conversion rate of 50% compared with a conversion rate of 61% in patients with a left atrial size of less than 50 mm (P = NS). Ibutilide-induced lengthening in the QTc interval was of 17 +/- 21 milliseconds. Cardiac complications were torsade de pointes (1 patient), nonsustained ventricular tachycardia (1 patient), and transient bradycardia (1 patient). Torsade de pointes was terminated with direct current cardioversion. Ibutilide appears to be an effective drug for conversion of recent-onset atrial fibrillation and flutter in elderly patients under monitored conditions. Complications are rare and transient.
1,828
New approaches for identifying antiarrhythmic drug targets.
Sudden cardiac death, secondary to ventricular fibrillation (VF), remains the leading cause of death in many developed countries. Substantial experimental and theoretical support exists for the idea that VF is caused by spiral wave re-entry. The initiation and subsequent break-up of spiral waves have been linked to electrical alternans, a phenomenon typically associated with a steeply sloped restitution relationship. Interventions that reduce the slope of the restitution relationship have been shown to prevent the induction of VF and to terminate existing VF in experimental models. These results suggest that electrical restitution may be a promising new target for antiarrhythmic therapies.
1,829
Significance of inducible ventricular flutter/fibrillation in risk stratification in patients with coronary artery disease.
Although inducible ventricular fibrillation (VF) has been used as an indication for prophylactic implantation of cardioverter-defibrillators (ICDs) in patients with coronary artery disease (CAD), the significance of inducible VF remains controversial.</AbstractText>Among 364 CAD patients who underwent electrophysiologic (EP) study for risk stratification, 23 patients, 12 without any history of VF or cardiac arrest (group A) and 11 with previously documented VF or cardiac arrest (group B), exhibited inducible ventricular flutter (VFL) or VF and subsequently underwent ICD implantation. Additionally, 11 CAD patients without previous VF or cardiac arrest, who had no inducible ventricular tachyarrhythmias but received an ICD, were included for comparison (group C).</AbstractText>During 2 years of follow-up, 1 (8%), 5 (45%), and 1 (9%) patients had appropriate ICD shocks in groups A, B, and C, respectively. The survival free from appropriate ICD shocks was significantly lower in group B compared to groups A and C (p&lt;0.05). There were no significant differences in age, sex, ejection fraction (EF), or induction protocol between groups A and B or between groups A and C.</AbstractText>In CAD patients with inducible VFL/VF, patients without any history of VF or cardiac arrest had significantly lower incidence of appropriate ICD shocks when compared to those with such clinical events. Conversely, in CAD patients without any history of VF or cardiac arrest, incidence of appropriate ICD shocks was similar regardless of inducible VFL/VF. Inducible VFL/VF is therefore not useful as an indication for prophylactic ICD implantation in this patient population.</AbstractText>
1,830
Rate versus rhythm control in atrial fibrillation.
AF remains the most common and most challenging arrhythmia. Although several new treatment modalities are available to restore and maintain sinus rhythm, the long-term success of such a strategy remains disappointing, often making rate control a good alternative. Factors associated with failures to restore and maintain sinus rhythm thereafter are a longer duration of AF, older patient age, atrial dilatation, poor functional class or heart failure, and hypertension. Recent trials comparing rate and rhythm control (see Box 1) could not show superiority of rhythm control and even gave some evidence that rhythm control may even be worse than rate control (more hospitalizations, more adverse drug effects). In general, however, these trials in general included older patients with persistent AF, and, most importantly the success of rhythm control was poor, stressing the fact that attempts to maintain rhythm control cannot be construed as being the same as actual maintenance of sinus rhythm. As mentioned previously, at least 37% to 74% of all patients in these trials were in AF and did not benefit from the possible advantages of sinus rhythm while they were exposed to the possible adverse effects of cardioversions and antiarrhythmic drugs. The decision to choose rhythm or rate control strategies should be individualized and depends on the expected benefit of restoring sinus rhythm, chance on failure to maintain sinus rhythm in the long-term, and the likelihood of adverse drug effects (Fig. 1). In all patients with AF, treatment should focus on underlying heart disease, anticoagulation, and control of ventricular rate during AF. In the authors' opinion, rhythm control remains first choice for patients with a first episode or highly symptomatic episodes of AF and for patients who have AF caused by a reversible cause (eg, hyperthyroidism, postcardiac surgery) or who have a high chance of remaining in long-term sinus rhythm (young patients, no hypertension, normal left atrium size, short preceding AF duration). Also patients with symptomatic AF who are suitable for ablation therapy (eg, focal AF, class IC flutter ), restoration and maintenance of sinus rhythm would be first choice. Rate control, however, will be a good option in asymptomatic patients and in patients in which rhythm control has failed or is very likely to fail. Also, if rhythm control does not improve symptoms or causes unwanted adverse effects (eg, frequent cardioversions, sinus node disease needing pacemaker implantation, or proarrhythmia), it should be abandoned. The present decision to opt for rhythm or rate control is determined mainly by the fact that in general, there is no single treatment that is highly effective and does not cause any adverse effects. If a 100% effective, 100% safe, and inexpensive drug or other treatment becomes available to restore and maintain sinus rhythm, it is more likely that the benefits of maintaining sinus rhythm could be proven, and one likely would opt for rhythm control in most patients.
1,831
Pharmacological rate control of atrial fibrillation.
To control ventricular rate in patients with AF, physicians should seek to control heart rate at rest and with exertion. The goal has to be achieved while minimizing costs and adverse effects. For emergency use, i.v. diltiazem or esmolol are drugs useful because of their rapid onset of action. They have to be used with caution in patients with concomitant left ventricular failure symptoms, however. For most patients with AF, chronic control of the ventricular rate can be achieved with one drug. For the chronic control of ventricular rate in patients with AF and normal ventricular function, diltiazem, atenolol, are metoprolol are probably the drugs of choice. For patients with AF and structurally abnormal hearts, atenolol, metoprolol, or carvedilol are appropriate choices. Adequate ventricular rate control by pharmacological agents should be evaluated by either 24-hour Holter monitoring or a submaximal stress test to determine the resting and exercise ventricular rate. If the mean ventricular rate is not close to 80 beats per minute, or the heart rate on moderate exertion is not between 90 to 115 beats per minute, a second agent to control the rate should be added. Excessive reductions in ventricular rates that could limit exercise tolerance should be avoided.
1,832
Implantable cardioverter defibrillator therapy in children with long QT syndrome.
We report our experience with implantable cardioverter defibrillator (ICD) implantation and follow-up in high-risk patients with congenital long QT syndrome (LQTS). Congenital LQTS is associated with significant risk of malignant ventricular arrhythmias and sudden cardiac death (SCD). ICD implant is recommended for prevention of SCD in this patient population, but there are few published data regarding the efficacy and side effects of such therapy. We report our experience with 12 patients who underwent ICD implant for high-risk LQTS at our center in the past 5 years with respect to implant complications, appropriate and inappropriate therapies, device follow-up, and the impact on lifestyle. During a follow-up of 34.7+/-16.6 months, appropriate therapies were noted in 5, inappropriate therapies in 4, and no therapies in 3 patients. Clusters of appropriate therapies were seen in 3 patients, 1 of whom subsequently died. Female sex and congenital deafness appear to be associated with a higher risk of appropriate therapies. One patient experienced two complications at implant that were successfully treated. ICD implantation in LQTS patients presenting with SCD or recurrent syncope despite beta-blocker therapy appears to be justified in preventing SCD risk. In asymptomatic siblings of SCD patients, the benefits of ICD implant are not clear from our data.
1,833
Atrial contraction after surgical isolation of the left atrial posterior wall concomitant with mitral valve replacement.
Surgical isolation of the left atrial posterior wall (LA-PW isolation) can terminate chronic atrial fibrillation associated with mitral valve disease. However, atrial contraction after LA-PW isolation has not been evaluated.</AbstractText>The study group comprised 14 patients (mean age, 63+/-14 years) with mitral valve disease who recovered and maintained regular sinus rhythm after LA-PW isolation. Before the procedure, and 2-3 weeks and 1 year after the LA-PW isolation, the patients underwent an echocardiographic study. The left atrial (LA) diameter decreased after the LA-PW isolation and the change became significant 1 year later (before: 50.1+/-5.1 mm, after 2-3 weeks: 46.0+/-4.9 mm; p&lt;0.05, after 1 year: 44.0+/-6.1 mm; p&lt;0.05 vs before the operation). The left ventricular (LV) end-diastolic diameter, LV ejection fraction and LV fractional shortening did not change significantly from before the LA-PW isolation and after 1 year. The time - velocity integral of the atrial wave (Ai) and atrial filling fraction significantly increased (Ai: 4.5+/-2.1 cm vs 5.8+/-2.3 cm; p&lt;0.05; atrial filling fraction: 15.4+/-7.7% to 19.2+/-8.3%; p&lt;0.05) during the follow-up period.</AbstractText>LA-PW isolation can benefit the restoration of regular sinus rhythm and, furthermore, the recovery of atrial contraction.</AbstractText>
1,834
Heart failure and the risk of shocks in patients with implantable cardioverter defibrillators: results from the Triggers Of Ventricular Arrhythmias (TOVA) study.
Left ventricular ejection fraction (LVEF) predicts device discharges in patients with implantable cardioverter-defibrillators (ICDs). The relationship between severity of congestive heart failure (CHF) and ICD discharges is less clear.</AbstractText>We prospectively analyzed the association between CHF and risk of appropriate ICD discharges in the Triggers Of Ventricular Arrhythmias (TOVA) study, a cohort study of ICD patients conducted at 31 centers in the United States. Reported shocks were confirmed for sustained ventricular tachycardia (VT) or fibrillation (VF) by analysis of stored electrograms. Proportional hazards models included CHF categorized by New York Heart Association class. Baseline CHF was present among 502 (44%) of 1140 patients; 170 (34%) had class I, 230 (46%) had class II, 97 (19%) had class III, and only 5 (1%) had class IV symptoms. During median follow-up of 212 days, 92 patients experienced 1 or more appropriate ICD discharges. Class III CHF was associated in a statistically significantly manner with ICD discharge for VT/VF (hazard ratio 2.40, 95% CI 1.16 to 4.98), even with adjustment for LVEF. The combination of LVEF &lt;0.20 and class III symptoms resulted in a particularly high risk of shocks for VT/VF (hazard ratio 3.90, 95% CI 1.28 to 11.92).</AbstractText>Class III CHF, an easily accessible clinical measure, is an independent risk factor, along with LVEF, for ventricular arrhythmias that require shock therapy among ICD patients. Whether patients with class III CHF benefit to a greater degree from ICDs and whether aggressive treatment of CHF in ICD patients may prevent ventricular arrhythmias remains to be determined.</AbstractText>
1,835
Neutrophil depletion reduces myocardial reperfusion morbidity.
We tested the hypothesis that depletion of neutrophil leukocytes from the cardioplegic and the initial myocardial reperfusion perfusates reduces clinical indices of reperfusion injury in patients undergoing elective coronary artery bypass.</AbstractText>We studied 160 consecutive patients who underwent standard coronary revascularization with cardiopulmonary bypass. Patients with recent myocardial infarction or coronary angioplasty were excluded. Cold blood cardioplegia was used. Just before aortic unclamping, the hearts were perfused retrograde with 250 mL of normothermic cardioplegic solution and 750 mL of blood (pump perfusate). Patients were randomly assigned to two groups. In 80 patients (treated), neutrophils and platelets were removed from all cardiac perfusate during aortic crossclamping with leukocyte filtration. In the remaining 80 patients (control group), leukocyte filtration was not used.</AbstractText>There was no significant difference between groups in age, sex, severity of disease, and number of bypass grafts implanted. Treated patients showed lower prevalence of low cardiac index and reperfusion ventricular fibrillation and lower levels of creatinine kinase MB isoenzyme and troponin I early postoperatively (p &lt; 0.05).</AbstractText>Neutrophil-filtered blood cardioplegia/reperfusion significantly reduced clinical and biochemical indices of myocardial reperfusion injury after elective coronary revascularization with cardiopulmonary bypass.</AbstractText>
1,836
Epicardial atrial defibrillation: successful treatment of postoperative atrial fibrillation.
Atrial fibrillation is the most common complication after cardiac surgery. Current medical treatment using antiarrhythmics and anticoagulants has a significant morbidity. The goal of this study was to determine if epicardial atrial defibrillation can be safely performed and return patients to sinus rhythm.</AbstractText>A prospective analysis of patients undergoing cardiac surgery was performed. Patients with a prior pacemaker/defibrillator, history of arrhythmia, preoperative antiarrhythmic, age greater than 85 years, history of stroke, or intraaortic balloon pump were excluded. Temporary epicardial atrial cardioversion wires were placed on the right and left atrium. Bipolar atrial and ventricular pacing wires were also placed. The wires were tested in the operating room. Patients who went into postoperative arial fibrillation were cardioverted with 3 J, 6 J, or 9 J.</AbstractText>There were 45 patients enrolled. Sixteen patients (35%) went into postoperative arial fibrillation during their hospital stay. Mean time to onset of arial fibrillation was 2.6 +/- 1.4 days after surgery. Fifteen patients were successfully cardioverted to sinus rhythm on the primary cardioversion, with mean of 5.7 +/- 2.4 J. One patient was cardioverted at 6 hours after onset of arial fibrillation, at 6 J. Recurrent arial fibrillation occurred in 4 patients during their hospital stay. All 4 of these patients were cardioverted with a mean of 6.4 +/- 2.6 J. All wires were removed the day before patients were discharged. There were no complications with wire insertion or removal. There were no adverse neurologic events. The mean hospital stay was 5.1 +/- 2.2 days. All patients were in sinus rhythm at 1 month follow-up.</AbstractText>The use of a temporary atrial defibrillator to resynchronize patients in postoperative arial fibrillation is safe and effective.</AbstractText>
1,837
The efficacy of supplemental magnesium in reducing atrial fibrillation after coronary artery bypass grafting.
Atrial fibrillation after coronary artery bypass is reported from 17% to 53%. Hypomagnesemia after this surgery is considered a contributing factor.</AbstractText>Two hundred-two coronary bypass patients were randomized to magnesium (n = 105) or placebo (n = 97). The experimental group received 80-mg magnesium sulfate per kilogram ideal weight in 100 mL dextrose 5% water 30 minutes preoperatively. Postoperatively, patients received 8-mg magnesium sulfate per kilogram ideal weight intravenous per hour more than 48 hours. The control group received dextrose 5% water at these intervals.</AbstractText>After the first bolus serum magnesium was experimental 4.75 mg/dL versus control 1.91 mg/dL, p less than 0.001, and remained different until postoperative day 4 (experimental 2.33 mg/dL vs control 2.26 mg/dL, p = 0.24). Atrial appendage and strap muscle were analyzed after the first bolus and after revascularization. There were no differences between groups in tissue magnesium or calcium. Urinary magnesium was elevated in the experimental (experimental 324.5 mg/24 hours, vs control 45.1 mg/24 hours, p = 0.01). Calcium excretion was higher (experimental 370 mg/24 hours vs control 186 mg/24 hours, p &lt; 0.001) and was associated with lower serum calcium. Serum calcium was higher in the control through the fourth postoperative day. The incidence of atrial fibrillation was experimental 32 of 105 (30.5%) versus control 41 of 97 (42.3%) p = 0.08. Atrial fibrillation was different on the first postoperative day (experimental 3/105, 2.9% vs control 9/97, 9.3%), p = 0.05.</AbstractText>Overall prophylactic magnesium supplementation does not significantly reduce atrial and ventricular arrhythmias. The only significant benefit of magnesium supplementation was on the first postoperative day.</AbstractText>
1,838
[Toxicity of topical administration of lidocaine].<Pagination><StartPage>657</StartPage><EndPage>660</EndPage><MedlinePgn>657-60</MedlinePgn></Pagination><Abstract><AbstractText>It is frequently described in international literature the possibility of toxicity by local anesthesics. The lidocaine is one of them. The problems with its local use are more frequent and known but topic toxicity is also possible. We want to describe a case of toxicity by topical administration of lidocaine (Xylocain) which caused neurological disease with convulsions, and cardiological disease with ventricular fibrillation, in a patient who came for a thyroplasty. Patient's evolution was satisfactory.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>G&#xf3;mez Mart&#xed;n-Zarco</LastName><ForeName>J M</ForeName><Initials>JM</Initials><AffiliationInfo><Affiliation>Departamento de Otorrinolar&#xed;ngolog&#xed;a, Cl&#xed;nica la Milagrosa, Madrid.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Lumbreras Fern&#xe1;ndez de C&#xf3;rdoba</LastName><ForeName>J</ForeName><Initials>J</Initials></Author><Author ValidYN="Y"><LastName>Ortiz Garc&#xed;a</LastName><ForeName>P</ForeName><Initials>P</Initials></Author></AuthorList><Language>spa</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList><VernacularTitle>Toxicidad por administraci&#xf3;n t&#xf3;pica de lidoca&#xed;na.</VernacularTitle></Article><MedlineJournalInfo><Country>Spain</Country><MedlineTA>Acta Otorrinolaringol Esp</MedlineTA><NlmUniqueID>14540260R</NlmUniqueID><ISSNLinking>0001-6519</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000779">Anesthetics, Local</NameOfSubstance></Chemical><Chemical><RegistryNumber>98PI200987</RegistryNumber><NameOfSubstance UI="D008012">Lidocaine</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000287" MajorTopicYN="N">Administration, Topical</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D000779" MajorTopicYN="N">Anesthetics, Local</DescriptorName><QualifierName UI="Q000008" MajorTopicYN="N">administration &amp; dosage</QualifierName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008012" MajorTopicYN="N">Lidocaine</DescriptorName><QualifierName UI="Q000008" MajorTopicYN="N">administration &amp; dosage</QualifierName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D008297" MajorTopicYN="N">Male</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008875" MajorTopicYN="N">Middle Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D020258" MajorTopicYN="N">Neurotoxicity Syndromes</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="Y">etiology</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2004</Year><Month>3</Month><Day>3</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2004</Year><Month>5</Month><Day>21</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2004</Year><Month>3</Month><Day>3</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">14992120</ArticleId><ArticleId IdType="doi">10.1016/s0001-6519(03)78463-5</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">14991980</PMID><DateCompleted><Year>2004</Year><Month>07</Month><Day>28</Day></DateCompleted><DateRevised><Year>2006</Year><Month>11</Month><Day>15</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0201-7563</ISSN><JournalIssue CitedMedium="Print"><Issue>6</Issue><PubDate><Year>2003</Year><Season>Nov-Dec</Season></PubDate></JournalIssue><Title>Anesteziologiia i reanimatologiia</Title><ISOAbbreviation>Anesteziol Reanimatol</ISOAbbreviation></Journal>[Optimisation of electroimpulse therapy of life threatening arrhythmia in patients with ischemic heart disease].
It is frequently described in international literature the possibility of toxicity by local anesthesics. The lidocaine is one of them. The problems with its local use are more frequent and known but topic toxicity is also possible. We want to describe a case of toxicity by topical administration of lidocaine (Xylocain) which caused neurological disease with convulsions, and cardiological disease with ventricular fibrillation, in a patient who came for a thyroplasty. Patient's evolution was satisfactory.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>G&#xf3;mez Mart&#xed;n-Zarco</LastName><ForeName>J M</ForeName><Initials>JM</Initials><AffiliationInfo><Affiliation>Departamento de Otorrinolar&#xed;ngolog&#xed;a, Cl&#xed;nica la Milagrosa, Madrid.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Lumbreras Fern&#xe1;ndez de C&#xf3;rdoba</LastName><ForeName>J</ForeName><Initials>J</Initials></Author><Author ValidYN="Y"><LastName>Ortiz Garc&#xed;a</LastName><ForeName>P</ForeName><Initials>P</Initials></Author></AuthorList><Language>spa</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList><VernacularTitle>Toxicidad por administraci&#xf3;n t&#xf3;pica de lidoca&#xed;na.</VernacularTitle></Article><MedlineJournalInfo><Country>Spain</Country><MedlineTA>Acta Otorrinolaringol Esp</MedlineTA><NlmUniqueID>14540260R</NlmUniqueID><ISSNLinking>0001-6519</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000779">Anesthetics, Local</NameOfSubstance></Chemical><Chemical><RegistryNumber>98PI200987</RegistryNumber><NameOfSubstance UI="D008012">Lidocaine</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000287" MajorTopicYN="N">Administration, Topical</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D000779" MajorTopicYN="N">Anesthetics, Local</DescriptorName><QualifierName UI="Q000008" MajorTopicYN="N">administration &amp; dosage</QualifierName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008012" MajorTopicYN="N">Lidocaine</DescriptorName><QualifierName UI="Q000008" MajorTopicYN="N">administration &amp; dosage</QualifierName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D008297" MajorTopicYN="N">Male</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008875" MajorTopicYN="N">Middle Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D020258" MajorTopicYN="N">Neurotoxicity Syndromes</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="Y">etiology</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2004</Year><Month>3</Month><Day>3</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2004</Year><Month>5</Month><Day>21</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2004</Year><Month>3</Month><Day>3</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">14992120</ArticleId><ArticleId IdType="doi">10.1016/s0001-6519(03)78463-5</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">14991980</PMID><DateCompleted><Year>2004</Year><Month>07</Month><Day>28</Day></DateCompleted><DateRevised><Year>2006</Year><Month>11</Month><Day>15</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0201-7563</ISSN><JournalIssue CitedMedium="Print"><Issue>6</Issue><PubDate><Year>2003</Year><Season>Nov-Dec</Season></PubDate></JournalIssue><Title>Anesteziologiia i reanimatologiia</Title><ISOAbbreviation>Anesteziol Reanimatol</ISOAbbreviation></Journal><ArticleTitle>[Optimisation of electroimpulse therapy of life threatening arrhythmia in patients with ischemic heart disease].</ArticleTitle><Pagination><StartPage>45</StartPage><EndPage>47</EndPage><MedlinePgn>45-7</MedlinePgn></Pagination><Abstract>The thorax impedance (TI) was measured in 230 patients with atrial and ventricular rhythm impairments according to L. Geddes et al. Gauze napkins moistened in physiological solution (PS) and in 7% hypertonic solution NaCl (HS) were used as contact material. The electrode diameter was approx. 12 cm. The use of HS was shown to bring about a TI decrease by 21% (from 77.0 +/- 0.9 to 61.0 +/- 1.0 ohm) versus the former. A high TI (60-146 ohm) was registered in 41 of 230 patients for whom PS was applied. HS ensures a TI decrease by 17% (to 79-128 ohm). Forty-six patients with atrial fibrillation underwent the electropulse therapy (EPT). Low-energy bipolar discharges (&lt; or = 65 J.) were effective in 31 (67.5%) of 46 patients, &lt; or = 65 J. Discharges were more effective in patients with TI &lt; or = 60 ohm versus patients with TI &gt; 60 ohm (76.7 and 52%, respectively, p = 0.04). With HS the efficiency of bipolar &lt; or = 90 J. discharges reached 83% (38/46). According to estimates, at least one more 100-115 J. discharge would be needed for 7 patients to ensure the similar EPT efficiency with PS.
1,839
[Transthoracic defibrillation. Physiologic and pathophysiologic principles and their role in the outcome of resuscitation].
As one major link in the chain of survival, early transthoracic (external) cardiac defibrillation is aimed at the termination of ventricular flutter and ventricular fibrillation. Most important to the success of defibrillation is the passage of a defined amount of current through a critical mass of heart muscle. Different transthoracic resistances reduce the effective density of the current within the heart. As for other therapeutic intervention procedures, recommendations for the optimal strength of current to be applied to the fibrillating heart need to be evaluated and defined for therapeutical defibrillation too. Unnecessarily high current density causes damage to the heart and should be prevented. By using biphasic waveforms in contrast to monophasic impulses, the amount of current can be reduced but the same or even higher efficacy is attained. Therefore possible myocardial damage might be clearly reduced. Even with individually altered thoracic impedance effective conversion of cardiac rhythm can be achieved by device-controlled compensation and biphasic waveforms. According to their different mechanisms or origin (electrically induced or spontaneously caused by organic heart disease) the probability of successful conversion of the cardiac rhythm by one single electrical impulse varies. The optimum point in time for defibrillation during resuscitation needs to be redefined. In order to improve comparability, further studies should use standardized definitions for successful defibrillation relating to the resulting cardiac rhythm.
1,840
A simulation study of the effects of cardiac anatomy in ventricular fibrillation.
In ventricular fibrillation (VF), the principal cause of sudden cardiac death, waves of electrical excitation break up into turbulent and incoherent fragments. The causes of this breakup have been intensely debated. Breakup can be caused by fixed anatomical properties of the tissue, such as the biventricular geometry and the inherent anisotropy of cardiac conduction. However, wavebreak can also be caused purely by instabilities in wave conduction that arise from ion channel dynamics, which represent potential targets for drug action. To study the interaction between these two wave-breaking mechanisms, we used a physiologically based mathematical model of the ventricular cell, together with a realistic three-dimensional computer model of cardiac anatomy, including the distribution of fiber angles throughout the myocardium. We find that dynamical instabilities remain a major cause of the wavebreak that drives VF, even in an anatomically realistic heart. With cell physiology in its usual operating regime, dynamics and anatomical features interact to promote wavebreak and VF. However, if dynamical instability is reduced, for example by modeling of certain pharmacologic interventions, electrical waves do not break up into fibrillation, despite anatomical complexity. Thus, interventions that promote dynamical wave stability show promise as an antifibrillatory strategy in this more realistic setting.
1,841
The anatomy of an arrhythmia.
Computer simulations are potentially effective approaches to unraveling the causes of lethal heart rhythm disorders. In this issue of the JCI, Xie et al. have embedded a well-characterized dynamic mechanism for arrhythmia development in an anatomically realistic computer model of the heart. Their demonstration that this simple mechanism governs the behavior of the complex model may provide a new target for strategies to prevent sudden death.
1,842
QT and JT dispersion in the drug-induced long QT syndrome in anaesthetized rabbits is accurately detected by a three-lead surface ECG measurement.
QT dispersion (QTd) can be measured from three leads of the ECG in patients with myocardial ischemia. However, whether QT and JT dispersion (QTd, JTd) can be calculated from a three-lead of the ECG in drug-induced long QT syndrome (LQTS) in animals remains elusive. Therefore, we determined to what extent a three-lead measurement of the surface ECG accurately detects dispersion of QT and JT in comparison with multi-lead assessments in anaesthetized rabbits, challenged with methoxamine and additionally infused intravenously with solvent or dofetilide.</AbstractText>Using several ECG leads in anaesthetized rabbits challenged intravenously with an alpha(1)-adrenoceptor agonist methoxamine, we assessed the QT and JT interval, as well as QT and JT dispersion, at baseline and in response to solvent or dofetilide (0.02 or 0.04 mg/kg/min iv for 60 min), an I(Kr) blocker. For that purpose, we recorded and analyzed the surface ECG and assessed QT and JT dispersion by four methods: (1) 12-lead ECG; (2) six precordial leads (V1-V6); (3) three leads most likely to contribute to the dispersion (aVF, V1, and V4); (4) three quasi-orthogonal leads (aVF, I, and V2). QT and JT dispersion were significantly lower in 6- and 3-lead measurements than in 12-lead measurement, both at baseline and during infusion of solvent or dofetilide. At 5 and 10 min of infusion, dofetilide at 0.02 or 0.04 mg/kg/min iv markedly increased QT and JT dispersion by 100% to 500% in all four ECG lead combinations. This dose regimen of dofetilide markedly prolonged QT and JT intervals in lead II, and was associated with high incidences of polymorphous ventricular tachycardia (PVT: 30% at 0.02 mg/kg/min; 100% at 0.04 mg/kg/min) and of ventricular fibrillation (VF: 17% with 0.02 mg/kg/min; 58% with 0.04 mg/kg/min).</AbstractText>Our present study shows that the measurement of QT and JT dispersion in three surface ECG leads only (aVF, I, V2 or aVF, V1 V4), instead of 12 ECG leads, is an appropriate approach to assess drug-induced heterogeneity or dispersion of ventricular repolarization in anaesthetized rabbits, both at baseline and during arrhythmogenic sensitization with methoxamine and challenged with dofetilide.</AbstractText>
1,843
Dynamics of QT dispersion in acute myocardial infarction.
We studied the dynamics of QT dispersion in patients with acute myocardial infarction, and compared them with those in controls.</AbstractText>Serial electrocardiograms of patients admitted to our institute with acute myocardial infarction were analyzed for QT dispersion, and compared with those of healthy age- and sex-matched controls. QT dispersion from 12 leads was measured as maximum QT minus minimum QT interval in ms. The mean QT dispersion of 114 +/- 29.6 ms was significantly higher in patients with acute myocardial infarction on admission as compared to 51.45 +/- 5.56 ms in controls (p &lt; 0.001). QT dispersion showed a dynamic change in patients with acute myocardial infarction who were thrombolyzed, being 109.11 +/- 5.77 ms, 87.59 +/- 5.88 ms, 75.89 +/- 18.33 ms, and 68.20 +/- 12.66 ms on admission, post-thrombolysis, and on days 3 and 7, respectively. During a similar time period, nonthrombolyzed patients showed a QT dispersion of 132.38 +/- 36.04 ms, 130.47 +/- 34.42 ms, 111.11 +/- 24.94 ms, and 106.25 +/- 27.64 ms, respectively: the difference between the 2 groups at all periods was significant (p &lt; 0.01). Mean QT dispersion values in patients who developed ventricular tachycardia or ventricular fibrillation were significantly higher than in patients who did not develop ventricular tachycardia or ventricular fibrillation (p &lt; 0.01).</AbstractText>Mean QT dispersion is significantly increased after acute myocardial infarction, and shows a dynamic decrease with time, the difference being more marked in thrombolyzed patients. Mean QT dispersion levels are higher in patients with ventricular tachycardia and ventricular fibrillation compared to patients with acute myocardial infarction without these arrhythmias. The changes in QT dispersion are dynamic, and it may serve as a non-invasive marker of susceptibility to malignant ventricular arrhythmias.</AbstractText>
1,844
Admission predictors of in-hospital mortality and subsequent long-term outcome in survivors of ventricular fibrillation out-of-hospital cardiac arrest: a population-based study.
Survival following out-of-hospital cardiac arrest (OHCA) from ventricular fibrillation (VF) is poor and dependent on a rapid emergency response system. Improvements in emergent early response have resulted in a higher percentage of patients surviving to admission. However, the admission variables that predict both short- and long-term survival in a region with high discharge survival following OHCA require further study in order to identify survivors at subsequent highest risk.</AbstractText>All patients with OHCA arrest in Olmsted County Minnesota between 1990 and 2000 who received defibrillation of VF by emergency services were included in the population-based study. Baseline patient admission characteristics in survivor and nonsurvivor groups were compared. Survivors to hospital discharge were prospectively followed to determine long-term survival.</AbstractText>Two hundred patients suffered a VF arrest. Of these patients, 145 (73%) survived to hospital admission (7 died within the emergency department) and 79 (40%) were subsequently discharged. Sixty-six (83%) were male, with an average age of 61.9 +/- 15.9 years. Univariate predictors of in-hospital mortality included call-to-shock time (6.6 vs. 5.5 min, p = 0.002), a nonwitnessed arrest (75.4 vs. 92.4%, p = 0.008), in-field use of epinephrine (27.8 vs. 93.4%, p &lt; 0.001), age (68.1 vs. 61.9 years, p = 0.017), hypertension (36.1 vs. 14.1%, p = 0.005), ejection fraction (32.4 vs. 42.4, p = 0.012), and use of digoxin (34.9 vs. 12.7%, p = 0.002). Of all these variables, hypertension [hazard ratio (HR) 4.0, 95% CI 1.1-14.1, p = 0.03], digoxin use (HR 4.5, 95% CI 1.3-15.6, p = 0.02), and epinephrine requirement (HR 62.0, 95% CI 15.1-254.8, p &lt; 0.001) were multivariate predictors of in-hospital mortality. Nineteen patients (24%) had died prior to the survey follow-up. Five patients experienced a cardiac death, resulting in a 5-year expected cardiac survival of 92%. Multivariate variables predictive of long-term mortality include digoxin use (HR 3.02, 95% CI 1.80-5.06, p &lt; 0.001), hypertension (HR 2.06, 95% CI 2.12-3.45, p = 0.006), and call-to-shock time (HR 1.18, 95% CI 1.01-1.38, p = 0.038).</AbstractText>A combined police/fire/EMS defibrillation program has resulted in an increase of patients surviving to hospital admission after OHCA. This study confirms the need to decrease call-to-shock times, which influence both in-hospital and long-term mortality. This study also identifies the novel demographic variables of digoxin and hypertension, which were also independent risk factors of increased in-hospital and long-term mortality. Identification of these variables may provide utility in identifying those at high-risk of subsequent mortality after resuscitation.</AbstractText>Copyright 2004 S. Karger AG, Basel</CopyrightInformation>
1,845
Out-of-hospital cardiac arrest in patients with cardiac amyloidosis: presenting rhythms, management and outcomes in four patients.
Primary systemic amyloidosis (AL) is a well-recognized systemic disease, and cardiac amyloidosis accounts for 10% of all nonischemic cardiomyopathies [J S C Med Assoc 97 (2001) 201-206]. The median survival of patients with symptomatic congestive heart failure secondary to cardiac amyloidosis is 4 months [New Engl J Med 336 (1997) 1202-1207; Am J Med 100 (1996) 290-298]. The cause of death in most patients is refractory congestive heart failure or sudden arrhythmic [Mayo Clin Proc 59 (1984) 589-597]. While there are reports of in-hospital arrhythmic deaths in these patients, there are no detailed reports that describe the presentation and management of patients with cardiac amyloidosis who have experienced an out-of-hospital cardiac arrest (OHCA). We describe here our experience with four patients with AL who had an OHCA, including presenting rhythms, interventions, and outcomes.
1,846
Human factors affect the quality of cardiopulmonary resuscitation in simulated cardiac arrests.
Cardiopulmonary resuscitation is a team endeavour. There are only limited data on whether team performance during cardiopulmonary resuscitation is influenced by behavioural issues. The aim of the study was to determine whether and how human factors affect the quality of cardiopulmonary resuscitation.</AbstractText>16 teams, each consisting of three health-care workers, were studied in a patient simulator. A scenario of witnessed cardiac arrest due to ventricular fibrillation was used. Ventricular fibrillation could be converted into sinus rhythm by two countershocks administered during the first 2 min or by two countershocks administered during the first 5 min provided that uninterrupted basic life support was started in under 60 s. Teams were rated to be successful if ventricular fibrillation was converted into sinus rhythm. Behavioural rating included leadership, task distribution, information transfer, and conflicts.</AbstractText>Only six out of 16 teams were successful. Compared with successful teams, teams that failed exhibited significantly less leadership behaviour (P=0.033) and explicit task distribution (P=0.035). All teams shared among them sufficient theoretical knowledge to successfully treat the simulated cardiac arrest.</AbstractText>In a scenario of simulated witnessed cardiac arrest almost two thirds of teams composed of qualified health-care workers failed to provide basic life support and/or defibrillation within an appropriate time window. Absence of leadership behaviour and absence of explicit task distribution were associated with poor team performance. Failure to translate theoretical knowledge into effective team activity appears to be a major problem.</AbstractText>
1,847
Factors involved in the susceptibility of spontaneously hypertensive rats to low K+-induced arrhythmias.
Disorders of intracellular Ca2+ homeostasis and intercellular coupling are thought to be crucial in the initiation and maintenance of malignant arrhythmias. The aim of this study was to investigate possible arrhythmogenic factors in spontaneously hypertensive rats (SHR) as well as their susceptibility to low K+-related arrhythmias. The experiments were performed on isolated hearts of 13 weeks-old SHR and age-matched Wistar Kyoto rats (WKY). Equilibration of the heart by Langendorff perfusion with oxygenated, 37 degrees C warm, standard Krebs solution at a constant pressure was followed by perfusion with low K+ solution for 60 min, unless sustained ventricular fibrillation occurred earlier. Electrocardiogram and epicardial monophasic action potentials (MAPs) were continuously monitored for incidence of arrhythmias and action potential changes. Myocardial tissue was taken for ultrastructural analysis and immunodetection of the main gap junction protein, connexin-43. The results showed that hypertrophic hearts of SHR exhibited prolongation of MAPs and a decrease in phosphorylation of connexin-43. Moreover, they were more prone to low K+-induced early after-depolarisations and ventricular premature beats as well as to connexin-43 and ultrastructural alterations than WKY rats. Consequently, the incidence of ventricular tachycardia (70% vs. 50%) and both transient (50% vs. 25%) and sustained (60% vs. 25%) ventricular fibrillation was higher in SHR than WKY rats. The results suggest that both prolongation of MAP and connexin-43 alterations are important arrhythmogenic factors facilitating arrhythmias in the setting of Ca2+ disorders due to hypokalaemia.
1,848
[Single nucleotide polymorphism in SCN5A and the distribution in Chinese Han ethnic group].
Mutations in voltage-gated sodium channel type (SCN5A) may evoke severe, life-threatening disturbances in cardiac rhythm, including long QT syndrome, idiopathic ventricular fibrillation (Brugada Syndrome), and isolated cardiac conduction disease. There is increasing awareness of the role of common polymorphisms in altering gene function and in susceptibility to diseases. The aim of the present study was to investigate single nucleotide polymorphism (SNP) in SCN5A gene and the distribution of these identified SNPs in Chinese Han nationality. SCN5A gene was sequenced by fluorescent labeling automatic sequencing method in 120 unrelated samples from Han nationality in South China. Allele frequency distribution was tested by Hardy-Weinberg equilibrium. The results showed that a total of 5 SNPs were identified in SCN5A gene, including three SNPs in code region, one SNP in regulatory region and the other in intron 23 adjacent to donor splicing site. The distribution of the SNPs in SCN5A gene was uneven. These allele frequencies in Han population of South China were as follows: G87A (A29A) 27.5%, A1673G (H588R) 10.4%, 4245+82A&gt;G 32.8%, C5457T (D1819D) 41.3% and G6174A 44.9% respectively. The SNPs G87A (A29A), 4245+82A&gt;G and G6174A were reported for the first time. There was no significant difference in the allele frequency of A1673G (H558R) within different ethical populations (P&gt;0.05). C5457T (D1819D) allele frequency of Han population in South China was similar to that observed in Japanese (P&gt;0.5), but higher than that in American (p&lt;0.005). There was no significant difference in the distribution of the SNPs between male group and female group (all p&gt;0.05). S1102Y and other 10 SNPs identified in other ethnic populations have not been detected in Chinese Han population. The allele distribution of SNPs was in good unity with the Hardy-Weinberg equilibrium. It is suggested that the SNP distribution of SCN5A gene varies within different nationalities. These data will be of use for genetic association studies of acquired arrythmias and investigation of sensitivity to drug therapy.
1,849
Pathophysiological findings in a model of persistent atrial fibrillation and severe congestive heart failure.
Develop and evaluate a model of persistent atrial fibrillation (AF) and severe congestive heart failure (CHF).</AbstractText>A single-chamber atrial pacemaker was implanted in pigs (20-30 kg). Burst atrial pacing at 42 Hz led to development of persistent AF. Immediately and 20 days after activation of the burst pacing protocol, animals underwent echocardiography. Heart rate, rhythm and general condition were monitored on a daily basis. After 20 days of atrial fibrillation, the animals were sacrificed. Conventional histological methods were used to evaluate microscopic structural changes.</AbstractText>In the pig model, persistent atrial fibrillation developed 5 +/- 0.7 days after initiation of the burst protocol. Ventricular response rate was 274 +/- 5 bpm during atrial fibrillation, leading to a tachycardiomyopathy. Heart failure symptoms occurred approximately 15 days after initiation of burst pacing. Increases in QT interval on electrocardiogram, heart weight-to-body weight ratio, and laboratory values suggestive of a hypercatecholaminergic state, as well as liver and kidney dysfunction occurred during the 20-day duration of the study. Microstructural changes consistent with cellular hypertrophy, variable fibrosis, myolysis and apoptosis were found in the atria and ventricles of the study animals.</AbstractText>The combined entity of atrial fibrillation and severe congestive heart failure leads to multiple organ dysfunction, ultrastructural and microscopic cardiac changes. Cellular hypertrophy, fibrosis and apoptosis are more prominent in this combined entity than previously reported models of lone atrial fibrillation or heart failure. This model can be used for further investigation into the pathophysiology and treatment of atrial fibrillation and advanced heart failure.</AbstractText>
1,850
In vivo electrophysiological effects of a selective slow delayed-rectifier potassium channel blocker in anesthetized dogs: potential insights into class III actions.
This study evaluated the in vivo electrophysiological effects of a highly selective slow delayed-rectifier K+-current blocker, HMR 1556, to gain insights into the consequences of selectively inhibiting the slow delayed-rectifier current in vivo.</AbstractText>Atrial and ventricular effective refractory periods, sinus node recovery time, Wenckebach cycle-length, atrial fibrillation duration and electrocardiographic intervals were measured before and after intravenous HMR 1556.</AbstractText>HMR 1556 increased atrial and ventricular refractory periods (e.g. by 6 +/- 4% and 27 +/- 6% at cycle lengths of 360 and 400 ms, respectively), QT intervals and sinus-node recovery times. Beta-adrenoceptor blockade with nadolol abolished all effects except those on ventricular refractoriness and changed positive use-dependent effects on refractoriness to reverse use-dependent ones. In the presence of dofetilide to block rapid delayed-rectifier current, HMR 1556 effects were potentiated (e.g. atrial and ventricular refractory periods increased by 26 +/- 3% and 34 +/- 3% at cycle lengths of 360 and 400 ms, respectively). HMR 1556 reduced vagal atrial fibrillation duration from 1077 +/- 81 to 471 +/- 38 s, an effect abolished by nadolol and greatly potentiated by dofetilide (duration 77 +/- 30 s). HMR 1556 increased Wenckebach cycle length only in the presence of dofetilide.</AbstractText>Slowed delayed-rectifier current inhibition affects atrial repolarization, sinus node function and atrial fibrillation in vivo, but only in the presence of intact beta-adrenergic tone, and delays ventricular repolarization even when beta-adrenoceptors are blocked. The slow delayed-rectifier current is particularly important when rapid delayed-rectifier current is suppressed, illustrating the importance of repolarization reserve.</AbstractText>
1,851
Sudden cardiac death.
Sudden cardiac death (SCD) due to ventricular tachyarrhythmias is a leading cause of death in the United States. This phenomenon is associated with coronary artery disease, valvular heart disease, nonischemic cardiomyopathies, congenital heart disease, primary electrical abnormalities, autonomic nervous system abnormalities, and other less common disorders. Evaluation and management of patients at risk for SCD (primary prevention) and of patients who have survived at least 1 episode of SCD (secondary prevention) have evolved in recent years because clinical trials have shown consistent benefit from implantation of cardioverter-defibrillators in appropriately selected patients. An evidence-based approach to primary and secondary prevention of SCD is presented.
1,852
The effect of bupivacaine on myocardial tissue hypoxia and acidosis during ventricular fibrillation.
Previously we observed that during bupivacaine-induced circulatory collapse, myocardial tissue pH declined more slowly than expected. Here we evaluated the effect of bupivacaine on myocardial acidosis induced by ventricular fibrillation. Sixteen dogs were anesthetized with 1.5% end-tidal isoflurane, the chest was opened, and a probe that measured oxygen pressure (PmO(2)), carbon dioxide pressure, pH, and temperature was inserted into myocardial tissue. After baseline measures, each dog received either 10 mg/kg bupivacaine (n = 8) or a sham saline treatment (n = 8). Three minutes later ventricular fibrillation was initiated electrically, and the rate of change in PmO(2) and pH during ventricular fibrillation was measured. Baseline physiological measures were similar in the two groups of dogs. During ventricular fibrillation there was a rapid decrease in PmO(2), and the rate of decrease was not different between sham- and bupivacaine-treated dogs. Tissue pH decreased during ventricular fibrillation, and the rate of decrease was 4 times faster in sham- compared with bupivacaine-treated dogs (P &lt; 0.05). These results show that bupivacaine attenuated myocardial tissue acidosis during ventricular fibrillation. This potentially beneficial effect may be a result of bupivacaine's ability to inhibit myocardial lactate and carbon dioxide production. This suggests a potential clinical application of bupivacaine for myocardial preservation.</AbstractText>In this animal study pretreatment with bupivacaine attenuated the progression of myocardial acidosis during ventricular fibrillation. The dogs regained normal hemodynamic variables after lipid infusion. The findings suggest such that bupivacaine may protect the heart against ischemic acidosis.</AbstractText>
1,853
Off-Pump Arterial Revascularization Using a New Reusable Device for Coronary Occlusion and Local Stabilization.
Abstract Background: Optimal local stabilization, an unobstructed view, and a free field for operation are of most importance during off-pump surgery to facilitate high-quality anastomoses. We report on a new reusable stabilizing platform for complete off-pump coronary revascularization. Methods: From May 2001 until June 2002, 118 consecutive patients (82 men, 36 women) with coronary artery disease (61 with 1-vessel, 42 with 2-vessel, and 15 with 3-vessel disease) and a mean age of 63. 6 +/- 10. 0 years (range, 41-88 years) were scheduled for complete off-pump arterial revascularization. The mean left ventricular ejection fraction was 56. 5% +/- 12. 5%(range, 25%-85%). Exposure of the coronary vessels was facilitated with deep pericardial slings. The target coronary vessel was snared twice with air-cushioned silicone loops and fixed to the platform, which was connected to a flexible steel arm. The platform is available in 3 versions with different connector angles to accommodate various anatomical conditions. Together with its flat design, the platform provides an unobstructed view and a free field of operation. Results: All operations were performed without any intraoperative complications, and all planned bypasses were carried out. The mean number of bypass grafts was 1. 7 +/- 0. 8 (range, 1-5). There was no early (30 days) mortality. The postoperative course was uneventful in all patients except for 1 reexploration for retrosternal bleeding, 10 patients with temporary atrial fibrillation, and 1 patient with reintubation after early extubation in the operating room because of respiratory insufficiency. Patients were discharged from the hospital in good condition 8. 7 +/- 2. 6 days (range, 5-18 days) after surgery. Conclusions: Our data indicate that complete arterial off-pump revascularization can be performed safely and effectively with a new reusable platform that provides excellent stabilization and an unobstructed view to the target coronary vessels.
1,854
On-Pump Beating Heart Surgery Offers an Alternative for Unstable Patients Undergoing Coronary Artery Bypass Grafting.
Abstract Background: Cardiac surgery has expanded the available approaches to aortocoronary artery bypass grafting to include approaches from minimally invasive surgery to full sternotomy. The heart can be arrested, left beating, or assisted with a right ventricular assist device or cardiopulmonary bypass pump. We have examined the 4 surgical modes that we use routinely in our large multisurgeon practice to determine our selection biases and the outcomes of the different techniques. Methods: Of the 4733 coronary artery bypass grafting (CABG) patients we studied from January 2000 through December 2002, 2332 (49.3%) operations were done on-pump on the arrested heart, 1908 (40.3%) were performed off-pump, 364 (7.7%) were performed on-pump on the beating heart, and 129 (2.7%) were performed with right heart assist. The preoperative risk factors, operative variables, and postoperative outcomes of the groups were analyzed. Results: Patients selected for on-pump beating heart procedures tended to be sicker with the highest predicted risk of death. We also selected patients who were in cardiogenic shock, in resuscitation, in emergent or salvage status, on dialysis, and with preoperative intra-aortic balloon pump (IABP) use for on-pump beating heart procedures at higher than expected rates. Patients with renal failure with or without dialysis, and those having a history of cerebrovascular accident tended not to be chosen for on-pump arrested heart procedures. Off-pump beating heart procedures were avoided for patients with cardiogenic shock or resuscitation, in emergent or salvage status, and with preoperative IABP use. The mortality rate in these patients was slightly worse in the on-pump beating heart group (4.4%) than in the on-pump arrested heart (3.5%) and off-pump (2.3%) groups (analysis of variance [ANOVA], P =.04). Atrial fibrillation occurred more frequently in both the on-pump beating heart (20.1%) and on-pump arrested heart (23.8%) groups (ANOVA, P &lt;.001). The on-pump groups had higher rates of blood product use and reoperation for bleeding and a prolonged ventilation rate, compared with the other procedures. On-pump patients had a statistically longer length of stay than either off-pump or right heart-assisted patients ( P &lt;.05) and required longer times on the ventilator and in the intensive care unit. Conclusions: Normothermic cardiopulmonary bypass with a beating heart is safe and efficacious and may be the method of choice for patients in cardiogenic shock, requiring resuscitation, or with previous CABG surgery, recent myocardial infarction, a low ejection fraction, or unstable arrhythmias.
1,855
Pentobarbital versus medetomidine-ketamine-fentanyl anaesthesia: effects on haemodynamics and the incidence of ischaemia-induced ventricular fibrillation in swine.
The present study was performed to compare haemodynamic variables at baseline and the incidence of ventricular fibrillation during the early phase of ischaemia in swine during pentobarbital or medetomidine-ketamine-fentanyl anaesthesia. Twenty-two swine (mean +/- SD: 29+/- 3 kg) were anaesthetized with sodium pentobarbital (induction with 36 mg/kg intraperitoneally, and maintenance with 5-20 mg/kg/h intravenously [i.v.]) and 6 swine (27+/- 3 kg) were anaesthetized with ketamine and fentanyl (premedicated with medetomidine 0.1 mg/kg and ketamine 10 mg/kg intramuscularly, induction with ketamine 20 mg/kg and fentanyl 0.025 mg/kg i.v., and maintenance with ketamine 20 mg/kg/h and fentanyl 0.025 mg/kg/h i.v.). After a stabilization period of 30 min, the left anterior descending coronary artery (LAD) was occluded for 10 min. Haemodynamic data and occurrence of ventricular fibrillation were recorded. The ischaemic area was measured by fluorescing microspheres. Swine anaesthetized with medetomidine-ketamine-fentanyl had significantly lower heart rate, myocardial contractility, peak left ventricular pressure, arterial blood pressure, aortic blood flow, myocardial blood flow and cardiac index at baseline, than swine anaesthetized with pentobarbital. Whereas none of the swine anaesthetized with pentobarbital fibrillated during the LAD occlusion, ventricular fibrillation occurred in 83% of the animals anaesthetized with medetomidine-ketamine-fentanyl (P&lt; 0.001). No significant difference was found in size of ischaemic area between the two groups. Thus, we show a depression in haemodynamic variables at baseline and a higher incidence of ventricular fibrillation during the early phase of ischaemia in swine anaesthetized with medetomidine-ketamine-fentanyl compared to swine anaesthetized with pentobarbital.
1,856
Effectiveness of metoprolol in preventing atrial fibrillation and flutter in the postoperative period of coronary artery bypass graft surgery.
To assess the effectiveness of metoprolol in preventing clinically detectable atrial fibrillation (AF) and flutter after coronary artery bypass graft (CABG) surgery.</AbstractText>An open, randomized study was carried out to treat 200 patients who had undergone isolated CABG surgery with extracorporeal circulation. The patients were randomized to either receive metoprolol orally or not to receive the medication in the postoperative period. The outcomes were the detection of sustained atrial AF and flutter, which were symptomatic or required treatment. The patients with the following characteristics were excluded from the study: baseline left ventricular ejection fraction &lt; 35%; previous AF; history of bronchospasm; second- and third-degree atrioventricular blocks, low cardiac output, and heart failure.</AbstractText>Arrhythmias occurred in 11 out of 100 patients in the metoprolol group and in 24 out of 100 patients in the control group (P=0.02). The relative risk (RR) was 0.46 (95% CI = 0.24-0.88), and the number necessary to treat (NNT) and avoid the outcome was 8 patients. AF was the arrhythmia most frequently observed (30/35). In 38 patients aged 70 years or more, the arrhythmias occurred in 2 out of 19 patients in the metoprolol group and in 10 out of 19 patients in the control group (c2 Yates: P=0.01). The relative risk was 0.20 (95% CI = 0.05-0.79) and the number necessary to treat was 2 patients.</AbstractText>Metoprolol is effective in preventing AF and flutter in the postoperative period of CABG surgery, and this effect was more evident in the group of elderly patients.</AbstractText>
1,857
Clinical implication of atrial and brain natriuretic Peptide in coronary artery bypass grafting.
Atrial natriuretic peptide and brain natriuretic peptide are known to be indices for heart failure. Atrial natriuretic peptide and brain natriuretic peptide changes in off-pump and on-pump coronary artery bypass grafting is hypothesized to be correlated to clinical implications of coronary artery bypass grafting. 20 consecutive off-pump and 20 consecutive on-pump coronary artery bypass grafting patients were studied. Perioperative atrial natriuretic peptide and brain natriuretic peptide values were measured and statistically analyzed in terms of 14 factors related to myocardial damage and recovery. Postoperative atrial natriuretic peptide plateaued on the third postoperative day and it decreased gradually down to the preoperative level by one month in the off-pump group. Postoperative brain natriuretic peptide plateaued, showed very slow decrease and it never reached down to the preoperative level. The peak brain natriuretic peptide level was correlated with aortic cross-clamp time, postoperative pleural effusion, and postoperative atrial fibrillation (p &lt; 0.01). The atrial natriuretic peptide change reflected surgical prevention of ventricular remodeling. Brain natriuretic peptide &gt; 450 microg.mL(-1) had strong predictive power for atrial fibrillation and pleural effusion and is a useful marker for management of coronary surgery patients.
1,858
Differential alterations of receptor densities of three muscarinic acetylcholine receptor subtypes and current densities of the corresponding K+ channels in canine atria with atrial fibrillation induced by experimental congestive heart failure.
Parasympathetic tone and congestive heart failure (CHF) are two of promoting factors in initiation and perpetuation of atrial fibrillation (AF). Recent studies indicate co-existence of multiple muscarinic acetylcholine receptor subtypes (mAChRs) that mediate several distinct K+ currents in the heart; inward rectifier K+ current IKACh by the M2, and two delayed rectifier K+ currents IKM3 and IK4AP by the M3 and M4 receptors, respectively. We studied the alterations of atrial mAChRs and their coupled K+ channels in the setting of AF in dogs with ventricular tachypacing-induced CHF. Whole-patch-clamp recordings showed that the current densities of IKACh (induced by 1 mM acetylcholine) and IK4AP (induced by 1 mM 4-aminopyridine) were &#xf1;45% and &#xf1;55% lower, respectively, while that of IKM3 (induced by 10 mM choline) was &#xf1;75% higher, at a plateau voltage of 0 mV in atrial myocytes from CHF than those from healthy hearts. In healthy hearts, IKACh comprised &gt;60%, and IKM3 and IK4AP &lt;30%, of the total outward K+ currents mediated by mAChRs at depolarized potentials (between -20 mV and +50 mV). In AF atria of CHF dogs, however, the contribution of IKM3 increased to approximately 50%, exceeding those of IKACh or IK4AP. Western blot analyses with atrial membrane protein samples indicated that receptor densities of the M2 and M4 subtypes decreased by approximately 33% and approximately 22%, respectively, whereas that of the M3 subtype increased by approximately 2.3 folds, in parallel to the alterations of the corresponding K+ currents. We conclude that differential alterations of mAChR subtypes underlie differential alterations of their coupled K+ channels in AF atria and these differential alterations may contribute to atrial remodeling in AF induced in the setting of CHF.
1,859
Radiofrequency ablation of atrial fibrillation.
Twenty-five patients (16 males, mean age 46 years) underwent radiofrequency ablation because of either paroxysmal (13 patients) or persistent atrial fibrillation (12 patients). Ablation aimed at earliest activation of spontaneous and catheter-induced repetitive ectopy in left and right atria and appendages, and pulmonary veins. Catheter-induced repetitive ectopy was defined as acute onset of a burst of rapid atrial premature beats on touching the wall, sustained irritability while at the spot and acute termination of rapid activity upon release of the catheter. Post-ablation patients received antiarrhythmic drugs to prevent tachycardias, thereby allowing reversal of atrial remodeling.</AbstractText>Lone atrial fibrillation was present in 19 patients, 4 patients had hypertension and 2 patients coronary artery disease with preserved left ventricular function. The median duration of the history of atrial fibrillation was 4 years (range 1-14 years) and the median number of antiarrhythmic drug failures 5 (range 1-6). Ablation was successful, i.e. no recurrences of atrial fibrillation with or without antiarrhythmic drugs in eight patients (32%) during a median follow-up of 28 months (range 18-52). The median number of foci was 3 (range 2-6) and 2 (range 1-7) in the successfully and unsuccessfully treated patients, respectively. Minor complications occurred in three patients.</AbstractText>Radiofrequency ablation of atrial fibrillation aiming at spontaneous and catheter-induced repetitive ectopy is a safe procedure. However, it is only successful in one third of the patients. Further investigations are warranted to identify the ideal patient, as well as to develop better ablation strategies.</AbstractText>
1,860
Clinical review: Reappraising the concept of immediate defibrillatory attempts for out-of-hospital ventricular fibrillation.
Despite well developed emergency medical services with rapid response advanced life support capabilities, survival rates following out-of-hospital ventricular fibrillation (VF) have remained bleak in many venues. Generally, these poor resuscitation rates are attributed to delays in the performance of basic cardiopulmonary resuscitation by bystanders or delays in defibrillation, but recent laboratory data suggest that the current standard of immediately providing a countershock as the first therapeutic intervention may be detrimental when VF is prolonged beyond several minutes. Several studies now suggest that when myocardial energy supplies begin to dwindle following more prolonged periods of VF, improvements in coronary artery perfusion must first be achieved in order to prime the heart for successful return of spontaneous circulation after defibrillation. Therefore, before countershocks, certain pharmacologic and/or mechanical interventions might take precedence during resuscitative efforts. This evolving concept has been substantiated recently by clinical studies, including a controlled clinical trial, demonstrating a significant improvement in survival when basic cardiopulmonary resuscitation is provided for several minutes before the initial countershock. Although this evolving concept differs from current standards and may pose a potential problem for automated defibrillator initiatives (e.g. public access defibrillation), successful defibrillation and return of spontaneous circulation have been rendered more predictable by evolving technologies that can score the VF waveform signal and differentiate between those who can be shocked immediately and those who should receive other interventions first.
1,861
Signal-averaged electrocardiogram in Ebstein's anomaly.
We sought to establish pathogenetic links between electrophysiology, histopathology, and ventricular tachyarrhythmias in patients with Ebstein's anomaly. The atrialized right ventricle (ARV) is the site of mechanically inducible ventricular tachyarrhythmias, but relations between the arrhythmogenic substrate, the type of tachyarrhythmias, and the trigger(s) have not been established. This study comprised 23 patients (10 men and 13 women; aged 18 to 58 years; mean 32 +/- 3) who did not undergo surgery and 6 pre- and postoperative patients with Ebstein's anomaly, diagnosed by transthoracic and transesophageal echocardiography. Twenty-one patients had classic Ebstein's anomaly and 2 had mild forms. Signal-averaged electrocardiograms (SAECGs) identified slow conduction by using 3 time-domain variables calculated by an automated algorithm and inspected visually. Two variables were required to establish the presence of late potentials. SAECGs were repeated in 6 patients after surgical exclusion of the ARV. Five surgical specimens of the ARV and the true right atrium were examined histologically. Mathematic simulations were used to illustrate anchored and unanchored spiral/scroll waves. SAECGs were positive in 21 patients with classic Ebstein's anomaly and were negative postoperatively in the 6 so studied. The ARV was characterized histologically by clusters of cardiomyocytes isolated within a fibrous matrix. We hypothesize that SAECGs identify slow conduction residing in the ARV, and that excitation of this arrhythmogenic substrate provokes spiral/scroll waves that cannot anchor because clusters of cardiomyocytes are isolated within a fibrous matrix. The waves meander erratically as polymorphic ventricular tachycardia or break up into ventricular fibrillation.
1,862
Brugada syndrome--an under-recognized electrical disease in patients with sudden cardiac death.
In 1992, Brugada and Brugada described 8 patients with a history of aborted sudden death and a distinct ECG pattern of right bundle-branch block with ST segment elevation in leads V1-V3 and normal QT interval in the absence of any structural heart disease. It is called Brugada syndrome now and is believed to be responsible for 4-12% of all sudden deaths and around 20% of deaths in patients with structurally normal hearts. Although this syndrome is observed worldwide and the exact prevalence is unknown, it is more common in the Southeast Asian countries. Repeated syncope, ventricular fibrillation, and sudden cardiac death have been reported in patients with Brugada syndrome. The clinical presentation of Brugada syndrome is distinguished by a male predominance and the appearance of arrhythmic events at an average age of 40 years. The Brugada syndrome is inherited in an autosomal dominant manner with incomplete penetrance and an incidence ranging between 5 and 66 per 10,000. The surface ECG manifestations of the syndrome can transiently disappear, but can be unmasked by potent sodium channel blockers in some cases. Mutations of the cardiac sodium channel SCN5A have been detectable in &lt;20% of patients with Brugada syndrome. Recent genetic studies have confirmed the genetic heterogeneity of the disorder. Antiarrhythmic drugs appear to be of little use in prolonging survival and in preventing recurrences of ventricular arrhythmias. To date, implantable cardioverter defibrillator remains the best therapy to prevent sudden death in these patients.
1,863
Mortality in patients after a recent myocardial infarction: a randomized, placebo-controlled trial of azimilide using heart rate variability for risk stratification.
Depressed left ventricular function (LVF) and low heart rate variability (HRV) identify patients at risk of increased mortality after myocardial infarction (MI). Azimilide, a novel class III antiarrhythmic drug, was investigated for its effects on mortality in patients with depressed LVF after recent MI and in a subpopulation of patients with low HRV.</AbstractText>A total of 3717 post-MI patients with depressed LVF were enrolled in this randomized, placebo-controlled, double-blind study of azimilide 100 mg on all-cause mortality. Placebo patients with low HRV had a significantly higher 1-year mortality than those with high HRV (&gt;20 U; 15% versus 9.5%, P&lt;0.0005) despite nearly identical ejection fractions. No significant differences were observed between the 100-mg azimilide and placebo groups for all-cause mortality in either the "at-risk" patients identified by depressed LVF (12% versus 12%) or the subpopulation of "high-risk" patients identified by low HRV (14% versus 15%) or for total cardiac or arrhythmic mortality. Significantly fewer patients receiving azimilide developed atrial fibrillation than did patients receiving placebo (0.5% versus 1.2%, P&lt;0.04). The incidences of torsade de pointes and severe neutropenia (absolute neutrophil count &lt; or =500 cells/microL) were slightly higher in the azimilide group than in the placebo group (0.3% versus 0.1% for torsade de pointes and 0.9% versus 0.2% for severe neutropenia).</AbstractText>Azimilide did not improve or worsen the mortality of patients after MI. Low HRV independently identified a subpopulation at high risk of mortality.</AbstractText>
1,864
Mechanisms of myocardial capture and temporal excitable gap during spiral wave reentry in a bidomain model.
Recent studies have demonstrated that regional capture during cardiac fibrillation is associated with an elevated capture threshold. It is typically assumed that the temporal excitable gap (capture window) during fibrillation reflects the size of the spatial excitable gap (excitable tissue between fibrillation waves). Because capture threshold is high, virtual electrode polarization is expected to be involved in the process. However, little is known about the underlying mechanisms of myocardial capture during fibrillation.</AbstractText>To clarify these issues, we conducted altogether 3168 simulations of single spiral wave capture in a bidomain sheet. Unipolar stimuli of strengths 4, 8, 16, and 24 mA and 2-ms duration were delivered at 99 locations in the sheet. We found that cathode-break rather than cathode-make excitation was the dominant mechanism of myocardial capture. When the stimulation site was located diagonally with respect to the core (upper left or lower right if the spiral wave rotates counterclockwise), the cathode-break excitation easily invaded the spatial excitable gap and resulted in a successful capture as a result of the formation of virtual anodes in the direction of the myocardial fibers. Thus, the spatial distribution of the temporal excitable gap did not reflect the spatial excitable gap.</AbstractText>The areas exhibiting wide temporal excitable gaps were areas in which the cathode-break excitation wave fronts easily invaded the spatial excitable gap via the virtual anodes. This study provides mechanistic insight into myocardial capture.</AbstractText>
1,865
Management of anticoagulant therapy for patients with prosthetic heart valves or atrial fibrillation.
There is a wide array of recommendations for the management of anticoagulant therapy in patients with mechanical heart valves. Especially the optimal intensity of vitamin K antagonists (VKA) is a ongoing matter of debate. On the basis of several studies, recommendations for daily clinical practice can be made. In this review, we discussed the studies and the different guidelines. Guidelines for the prevention of thromboembolic complications in patients with atrial fibrillation are more stringent. VKA with a target INR between 2.0 and 3.0 is more effective in the prevention of stroke than aspirin, especially in the presence of riskfactors for thromboembolism (age above 65, previous thromboembolism, history of hypertension and diabetes, enlarged left atrial diameter and left ventricular dysfunction). In the absence of clinical or echocardiographical riskfactors for thromboembolism, patients may be safely treated with aspirin.
1,866
[Laymen groups trained to use defibrillators in rural areas?].
Patients suspected of having an acute myocardial infarction (AMI) constitute a group with particularly high risk of developing cardiac arrest caused by ventricular fibrillation (VF). It is conceivable that a strategy of shortening the interval until defibrillation skills are brought to the patient can be more fruitful in rural areas than the now prevailing recommendations of obtaining rapid defibrillation after cardiac arrest is manifest. A project is being organized in a Norwegian rural municipality, where laymen are being trained in the use of automated external defibrillators (AEDs), and are organized in groups according to place of residence or work. Their main task is to bring the AED to patients with suspected AMI and be prepared to use the AED if cardiac arrest should supervene. The main objective of a planned five-year study is to gather information as to what degree of mastering and what degree of stress the participants of the project experience, and to see if it is possible to maintain an organisation like this over a longer period of time. Preliminary results from the first half-year of the project indicate that the participants are entering the project with a reasonable degree of individual self-confidence and have even greater confidence in the group to which they belong. This might suggest that it is an advantage for participants in AED projects to be organised in groups in which mutual support is experienced.
1,867
[Public access defibrillators--beneficial?].
In Norway, every year more than 3000 persons suffer sudden cardiac death caused by ventricular fibrillation. The present recommendations of international expert committees are that the use of public-access defibrillators should be encouraged, including training of non-medical personnel.</AbstractText>In order to evaluate the validity of such recommendations, we performed searches in Medline on relevant keywords and evaluated articles thus identified and their references. We selected studies on countries, cities, public access defibrillator projects, and on epidemiology of cardiac arrest and ventricular fibrillation.</AbstractText>Studies of the public-access defibrillation strategy reported the highest frequencies of survival. Studies from cities gave highly variable results; those for entire countries poor results. Different populations have different results of survival, and commonly used predictor models do not comprehensibly explain these findings. Over time there is a falling frequency of ventricular fibrillation as the cause of cardiac arrest.</AbstractText>Application of the strategy of public-access defibrillators will not result in significantly improved survival from cardiac arrest in Norway.</AbstractText>
1,868
Pharmacokinetics and pharmacodynamic effects of amiodarone in plasma of ponies after single intravenous administration.
Atrial fibrillation is a well-known heart disease in horses. The common therapy consists of administration of quinidine. More potent antiarrhythmic drugs have become available for human therapy and the use of these as alternatives to quinidine for equine antiarrhythmic therapy is a matter of interest. Amiodarone (AMD) is used in human medicine for treatment of many arrhythmias, including atrial fibrillation. Its disposition in horses has not yet been investigated. The purpose of this study was to measure the effect of single intravenous doses of amiodarone (5 and 7 mg/kg) on the surface electrocardiogram (ECG) of healthy minishetland ponies during the first 2 days after drug administration and to calculate pharmacokinetic parameters with a physiologically based pharmacokinetic model (PBPK) using amiodarone and desethylamiodarone (DAMD) plasma levels that were determined by high-performance liquid chromatography (HPLC). As expected for a K(+)-channel-blocker, the main effect on the measured ECG could be seen on the ventricular complex, as the QT interval and the T wave showed statistically significant alterations. The doses investigated were well tolerated clinically. Results from the pharmacokinetic model were found to compare well with literature data of rats, dogs, and humans. It showed a rapid distribution in the tissue, beginning with the rapidly perfused tissue, like the heart, followed by slowly perfused tissues, and finally an accumulation in fat. The half-life for total elimination was calculated to be 16.3 days with 99% eliminated by 97 days. The model predicts that approximately 96% of amiodarone is eliminated as desethylamiodarone in urine, 2% eliminated as desethylamiodarone in bile, and 2% as other metabolites.
1,869
Sodium channel gene (SCN5A) mutations in 44 index patients with Brugada syndrome: different incidences in familial and sporadic disease.
The Brugada syndrome (BS) is a distinct form of idiopathic ventricular fibrillation and may cause sudden cardiac death in healthy young individuals. In the surface ECG, BS can be recognized by an atypical right bundle branch block and ST-segment elevation in the right precordial leads. Mutations in the cardiac sodium channel gene SCN5A are only known to cause BS. In a multi-center effort, we have collected clinical data on 44 unrelated index patients and family members and performed a complete genetic analysis of SCN5A. In 37% the disease was familial, whereas in the majority it was sporadic (63%). Five novel SCN5A mutations (2602delC, resulting in: E867X; 2581_2582del TT: F861fs951X; 2673G&gt;A: E1225K; 4435_4437delAAG: K1479del; and 5425C&gt;A: S1812X) were found and were randomly located in SCN5A. Mutation frequencies (SCN5A+) differed significantly between familial (38%) and sporadic disease (0%) (p=0.001). Disease penetrance was complete in the SCN5A+ adult patients, but incomplete in SCN5A+ children (17%). Genetic testing of SCN5A is especially useful in familial disease to identify individuals at cardiac risk. In sporadic cases, however, a genetic basis and the value of mutation screening has to be further determined. These results are in line with a possibly genetic and clinical heterogeneity of BS.
1,870
Two components of delayed rectifier K+ current in heart: molecular basis, functional diversity, and contribution to repolarization.
Delayed rectifier K+ current (IK) is the major outward current responsible for ventricular repolarization. Two components of IK (IKr and IKs) have been identified in many mammalian species including humans. IKr plays a pivotal role in normal ventricular repolarization. A prolongation of action potential duration (APD) under a variety of conditions would favor the activation of IKs so that to prevent excessive repolarization delay causing early afterdepolarization. The pore-forming a subunits of IKr and IKs are composed of HERG (KCNH2) and KvLQT1 (KCNQ1), respectively. KvLQT1 is associated with a function-altering beta subunit, minK to form IKs. HERG may be associated with mink (KCNE1) and/or minK-related protein (MiRP1) to form IKr, but the issue remains to be established. IKs is enhanced, whereas IKr is usually attenuated by beta-adrenergic stimulation via cyclic adenosine 3',5'-monophosphate (cAMP)/protein kinase A-dependent pathways. There exist regional differences in the density of IKr and IKs transmurally (endo-epicardial) and along the apico-basal axis, contributing to the spatial heterogeneity of ventricular repolarization. A decrease of IKr or IKs by mutations in either HERG, KvLQT1, or KCNE family results in inherited long QT syndrome (LQTS) with high risk for Torsades de pointes (TdP)-type polymorphic ventricular tachycardia and ventricular fibrillation. As to the pharmacological treatment and prevention of ventricular tachyarrhythmias, selectively block of IKs is expected to be more beneficial than selectively block of IKr in terms of homogeneous prolongation of refractoriness at high heart rates especially in diseased hearts including myocardial ischemia.
1,871
Evolution of activation patterns during long-duration ventricular fibrillation in dogs.
Although resuscitation for sudden cardiac arrest attempts are frequently not instituted for several minutes after the onset of ventricular fibrillation (VF), previous mapping studies have examined only the first 40 s of VF or have involved isolated perfused hearts that did not become ischemic during VF. We applied quantitative pattern analysis to mapping data throughout the first 10 min of VF acquired from a 21 x 24 unipolar electrode array located on the ventricular epicardium of six open-chest dogs. The following twelve descriptors were continuously quantified: 1) number of wavefronts, 2) incidence of reentry, 3) wavefront propagation velocity, 4) incidence of breakthrough/focus, 5) incidence of block, 6) mean area activated by the wavefronts, 7) wavefront fractionations, 8) wavefront collisions, 9) multiplicity index, 10) repeatability, 11) negative peak rate of voltage change, and 12) peak frequency of activation. Cluster analysis of these descriptors divided VF into five stages (stages i-v). The values of most descriptors (except block and breakthrough incidence) increased during stage i (1-11 s after VF induction) and maintained high values with rapid dynamic fluctuations during stage ii (12-62 s). Descriptors changed quickly to values indicating greater organization during stage iii (63-86 s), decreased steadily during stage iv (87-310 s), and approached zero during stage v (311-600 s). There was a high incidence of reentry just before, during, and after stage iii. In conclusion, during the first 10 min, VF can be divided into five stages according to the evolution of electrophysiological characteristics. All of the parameters show a rapid deterioration during VF, except for a temporary reversal approximately 1 min after induction when activation briefly became more organized. Thus a quantitative description of activation does not uniformly decrease as VF progresses, but undergo rapid changes and exhibit a brief interval of increased organization after approximately 1 min of VF. Further studies are warranted to determine whether these changes, particularly the increased organization of stage iii, have clinical consequences, such as an alteration in defibrillation efficacy.
1,872
Comparison of echocardiographic methods in assessing severity of mitral regurgitation in patients with mitral valve prolapse.
Mitral regurgitation (MR) shows different characteristics in mitral valve prolapse (MVP); hence, it is important to assess MR severity accurately in these patients. The study aim was to compare Doppler echocardiographic methods in making such assessment.</AbstractText>Forty-seven patients with confirmed MVP and at least moderate mitral insufficiency, as established by Doppler echocardiography, were studied. Quantitative Doppler was used as the reference standard method. Color Doppler mapping was used to determine regurgitant jet area (JA/LAA), flow convergence (EROA-PISA) and vena contracta width (VCW). Systolic pulmonary venous flow reversal (SPVFR) and mitral E-wave velocity were also monitored.</AbstractText>Univariate analysis showed severe MR to be significantly correlated to age, presence of atrial fibrillation, left ventricular systolic and diastolic diameter, left atrial diameter, mitral E velocity, JA/LAA, VCW, EROA-PISA and the presence of SPVFR. On multivariate analysis, the strongest determinants of severe MR were EROA-PISA, VCW and E velocity. The greatest area under the receiver-operator curve for diagnosing severe MR was observed with EROA-PISA. The 45-mm2 threshold of EROA-PISA had the highest risk ratio of severe MR with a high sum of sensitivity and specificity. However, the JA/LAA had the lowest risk ratio and negative predictive value for severe MR.</AbstractText>PISA, VCW, E velocity and SPVFR measurements may be used to evaluate MR severity semi-quantitatively in patients with MVP; however, the ratio of JA/LAA appears to be a less reliable method in this respect.</AbstractText>
1,873
Design of an integrated sensor for in vivo simultaneous electrocontractile cardiac mapping.
While there is extensive mapping of the spread of electrical activity in the heart, there have been no measurements of electrical and localized mechanical, or contractile, activity. Yet the development of effective treatments for diseases like chronic heart failure and cardiac hypertrophy depend on the ability to quantify improvements in electrocontractile function. In this paper, we present a sensor that is capable of making simultaneous, electrocontractile measurements. Its small size facilitates placement in multiple myocardial sites for multichannel studies. Semiconductor strain gages are used for force sensing, and Ag/AgCl-plated tungsten electrodes act as electrogram sensors. The sensor contains electronics on-board, including instrumentation amplifiers and a microprocessor for data sampling and analog-to-digital conversion. Each sensor can accurately detect 0-245+/-5 mV in two electrogram channels with a sensitivity of 0.96+/-0.2 mV/step and less than 2% error, and 0-144+/-29 g of contractile force with a sensitivity of 0.56+/-0.11 g/step in the analog-to-digital conversion and less than 6% error. The sensor has been tested in vivo in open-chest rabbit and pig mapping studies. These studies indicated that the average peak-to-peak contractile force at the apex is smaller in the rabbit than the pig (13.3 versus 40.3 g), that the average peak-to-peak contractile force in the pig is smaller near the base than near the apex (31.3 versus 40.3 g), and that contractile force is visibly decreased during ventricular fibrillation compared to normal sinus rhythm.
1,874
Depression in acute coronary syndrome.
This study examined the prevalence of depression based on scores of 200 patients with acute coronary syndrome on the Emotion Profile Index of Plutchik and its relationship with the type of acute coronary syndrome and the severity of ischemic heart disease. Patients with acute coronary syndrome scored higher on depression than the control group. There was no difference in scores on Depression by type of acute coronary syndrome and no significant mean differences on Depression for patients with and without left ventricular failure. Patients with acute myocardial infarction and ventricular fibrillation scored lower on Depression than other patients with acute myocardial infarction and control group. This study supports the view that patients with acute myocardial infarction and ventricular fibrillation and lower scores on Depression have good prognosis during hospitalization and maybe for the long term.
1,875
Estimated global transmural distribution of activation rate and conduction block during porcine and canine ventricular fibrillation.
We quantified ventricular fibrillation (VF) activation rate, conduction block, and organization transmurally in pigs and dogs, whose transmural Purkinje distribution differ. In six pigs and five dogs, 75 to 100 plunge needles, containing four electrodes for the right ventricle (RV) and six electrodes for the left ventricle (LV) and septum, were inserted in vivo. Six VF episodes were electrically initiated and allowed to last for 47 to 180 seconds. From the FFT power spectra, dominant frequency (DF), an estimate of activation rate, and incidence of double peaks (DPI), an estimate of conduction block, were calculated every 8 ms at each electrode. DF was highest at the epicardium and lowest at the endocardium, whereas DPI was highest at the endocardium and lowest at the epicardium for the entire LV and the RV base in both pigs and dogs for the first 70 seconds of VF. This distribution changed little throughout the first 3 minutes of VF in pigs but reversed in dogs by 2 minutes of VF. In conclusion, estimated activation rates and conduction block incidence during VF are not uniformly distributed transmurally. During the first minute of VF, the faster activating LV base epicardium exhibits less estimated block than the slower endocardium, raising the possibility that faster activating epicardium generates wavefronts that drive the endocardium early during VF. Constancy of this pattern in pigs but its reversal by 2 minutes in dogs is consistent with the hypothesis that activation during later VF is driven by Purkinje fibers.
1,876
Cardiac arrhythmia as presentation of snakebite.
Snakebite cases may have myriad presentations. we are describing a previously healthy young man presenting within half an hour of snakebite who experienced abrupt fatal cardiac rhythm changes ranging from bradycardia to ventricular tachycardia/fibrillation over a short span of time.
1,877
The different electrophysiological characteristics in children with Wolff-Parkinson-White syndrome between those with and without atrial fibrillation.
Atrioventricular reciprocating tachycardia (AVRT) is known to be the most common supraventricular tachycardias in childhood. Because AF with rapid ventricular response may degenerate to ventricular fibrillation through conduction of accessory pathways (APs), it can be potentially life-threatening in some pediatric patients with WPW syndrome. However, information about WPW syndrome children associated with AF is limited. The purpose of this study was to investigate the specific electrophysiological characteristics in pediatric patients with WPW syndrome and AF. From July 1992 to February 2002, 51 pediatric patients with manifest WPW syndrome and documented AVRT underwent electrophysiological study and radiofrequency catheter ablation. In these patients, two (4%) were found to have several spontaneous episodes of AF recognized on 12-lead standard ECG or 24-hour Holter monitoring. Eleven (22%) patients had AF induced by rapid atrial pacing during the baseline procedure of electrophysiological study. The children with manifest WPW syndrome were divided into two groups: those with AF (group 1; n = 11) consisted of seven male and four female children (mean age 15 +/- 3 years, range 10-18), and those without AF (group 2; n = 40) consisted of 22 boys and 18 girls (mean age 16 +/- 3 years, range 7-18). The study excluded a patient who had Ebstein's anomaly associated with moderate tricuspid regurgitation and right atrial enlargement. The onset and duration of symptoms were not significantly different between the two groups. Comparing the electrophysiological characteristics, the atrial effective refractory period (ERP) was shorter in WPW syndrome children with AF (170 +/- 36 vs 190 +/- 38 ms, P = 0.041). This study demonstrated that the pediatric WPW syndrome patients with AF had different electrophysiological characteristics from those without AF.
1,878
Lower observed versus expected (based on U.S. age and gender specific rates) survival in patients treated for near-fatal ventricular arrhythmias.
Implantable cardioverter defibrillators (ICDs) have improved survival for patients with ventricular fibrillation (VF) or sustained vertricular tachycardia (VT). However, the survival of these patients compared to the general population has not been assessed. Observed survival rates for patients randomized to either antiarrhythmic drug therapy (mainly amiodarone) arm or ICD arm were compared to expected rates, calculated using age and sex-specific survival rates derived from the 1989-1991 US population life tables and applied to the age and sex distribution of patients in each arm. Consistent with the results of the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, patients randomized to receive ICDs experienced significantly higher survival than those in the drug arm; however, both groups experienced significantly lower survival than expected using age and gender matched U.S. survival rates. Within arms, the difference between the observed and expected rates increased over 3 years of follow-up from 7.7% to 15.3% for the ICD arm, and from 14.6% to 26.4% for the drug arm. These results quantify the improvements in survival that can be expected for VF or VT patients using drug or ICD therapies and underscore the need for continued research into methods for further improving the overall level of health of these patients.
1,879
Comparison of step-down and binary search algorithms for determination of defibrillation threshold in humans.
Determination of DFT is an integral part of ICD implantation. Two commonly used methods of DFT determination, the step-down method and the binary search method, were compared in 44 patients undergoing ICD testing for standard clinical indications. The step-down protocol used an initial shock of 18 J. The binary search method began with a shock energy of 9 J and successive shock energies were increased or decreased depending on the success of the previous shock. The DFT was defined as the lowest energy that successfully terminated ventricular fibrillation. The binary search method has the advantage of requiring a predetermined number of shocks, but some have questioned its accuracy. The study found that (mean) DFT obtained by the step-down method was 8.2 +/- 5.0, whereas by the binary search method DFT was 8.1 +/- 0.7 J, P = NS. DFT differed by no more than one step between methods in 32 (71%) of patients. The number of shocks required to determine DFT by the step-down method was 4.6 +/- 1.4, whereas by definition, the binary search method always required three shocks. In conclusion, the binary search method is preferable because it is of comparable efficacy and requires fewer shocks.
1,880
Effects of intravenous nifekalant, a class III antiarrhythmic drug, on atrial vulnerability parameters in patients with paroxysmal atrial fibrillation.
Nifekalant, a class III antiarrhythmic drug, has been shown to suppress ventricular tachyarrhythmias, but its effects on AF are unclear. The aim of this study was to clarify the effects of nifekalant on the atrial vulnerability parameters in patients with paroxysmal AF. The study included 18 patients with paroxysmal AF who underwent electrophysiological study before and after intravenous infusion of nifekalant. The atrial electrophysiological parameters including the atrial effective refractory period (AERP), maximum intraatrial conduction delay, and wavelength index, calculated as the ratio of AERP to the maximum conduction delay, were quantitatively measured at baseline and during nifekalant infusion. The mean AERP was significantly prolonged from 214 +/- 27 ms at baseline to 242 +/- 39 ms after nifekalant (P &lt; 0.001). Although earlier studies have shown that nifekalant does not affect the atrial conduction time, the mean maximum conduction delay of the study patients was significantly prolonged from 59 +/- 19 ms at baseline to 72 +/- 28 ms after nifekalant (P = 0.015). There was no significant difference in the wavelength index at baseline (4.1 +/- 1.7) and after nifekalant (4.1 +/- 2.5). However, when the differences of AERP and wavelength index were defined as each parameter during nifekalant infusion minus that at baseline, the difference of AERP showed a direct positive correlation with that of the wavelength index (P = 0.013). In conclusion, nifekalant may be effective in the prevention of AF due to prolongation of the AERP. However, in those patients who have a lesser degree of prolongation of the AERP by nifekalant, the wavelength index tended to be decreased, suggesting that the drug might augment the propensity for AF.
1,881
T wave spectral variance for noninvasive identification of patients with idiopathic dilated cardiomyopathy prone to ventricular fibrillation even in the presence of bundle branch block or atrial fibrillation.
Conventional methods using Holter ECG recordings for noninvasive risk stratification are limited in patients with idiopathic dilated cardiomyopathy (IDC) prone to ventricular fibrillation (VF) having atrial fibrillation (AF) or bundle branch block (BBB). We therefore investigated, whether spectral assessment of beat-to-beat alternations of repolarization is associated with VF in these patients. Twenty-four-hour Holter ECG recordings in 462 patients with IDC were used. The VF group comprised of 64 consecutive patients who survived cardiac arrest, the no VF group consisted of 398 consecutive patients without a history of malignant ventricular arrhythmia. One hundred patients with ischemic cardiomyopathy (ICM) served as a control group. In each patient, 1,024 consecutive T waves were aligned using cross correlation methods. Two-dimensional Fourier transform (2D FFT) used the data matrix of 1,024 consecutive 200-ms segments centered to the T wave peak. Power spectra of the 2D FFT revealed the frequency content of the T wave in the first dimension and the periodicity of this frequency content in the second dimension. The ratio between periodic frequency contents and the sum of nonperiodic and periodic frequency contents between 0.5 and 50 Hz is equal to the T wave spectral variance (TWSV) index. Thus, TWSV index = 0 would mean that all 1,024 T waves are identical and TWSV index = 1 would mean that the 1,024 T waves are totally variable. The TWSV index was significantly higher in the VF group (0.93 +/- 0.14) than in the no VF group (0.53 +/- 0.13, P &lt; 0.01). The best cutoff between the VF and the no VF group was achieved by using a TWSV index of 0.75 (sensitivity = 89%, specificity = 78%). No significant differences were observed between patients with and without AF or with and without BBB, and between patients with IDC and ICM. Even in the presence of BBB or AF spectral assessment of T wave alternations by TWSV index using 2D FFT in Holter ECG recordings, allows the identification of patients with IDC at risk for VF.
1,882
Mitral valve replacement through right thoracotomy after previous coronary artery bypass grafting: the usefulness of brachial artery cannulation, perfused ventricular fibrillation with moderate hypothermia, and minimal dissection techniques.
It has been reported by several authors that a right thoracotomy for mitral valve surgery can be useful after previous coronary aortery bypass grafting (CABG). A 76-year-old man with mitral valve regurgitation after previous CABG underwent mitral valve replacement with some modified techniques. Cardiopulmonary bypass was established with right brachial artery cannulation and right femoral venous cannulation with the aid of vacuum-assisted venous drainage. Ventricular fibrillation (VF) was induced by rapid pacing of the ventricle, and mitral valve replacement was performed under perfused VF with moderate hypothermia. The patient's postoperative course was uneventful. This method appears to be a safe and easy alternative mitral valve surgery for complicated cases of this type.
1,883
The electrical restitution curve revisited: steep or flat slope--which is better?
The electrical restitution curve (ERC) traditionally describes the recovery of action potential duration (APD) as a function of the interbeat interval or, more correctly, the diastolic interval (DI). Often overlooked in modeling studies, the normal ventricular ERC is triphasic, starting with a steep initial recovery at the shortest DIs, a transient decline, and a final asymptotic rise to a plateau phase reached at long DIs. Recent studies have proposed that it would be advantageous to lower the slope of the ERC by drug intervention, as this might reduce the potential for electrical alternans and ventricular fibrillation. This review discusses the pros and cons of a flat versus steep slope of the ERC and draws attention to mechanisms thatjustify the (physiologically) steep slope, rather than a flat slope, as a better design against arrhythmias. Five potential mechanisms are discussed, which allows for a different interpretation of the effect of the slope on arrhythmogenicity. The most important appears to be the physiologic rate adaptive shortening of APD that, by reciprocal lengthening of the DI, allows the subsequent APD to move more quickly from the steep initial ERC phase onto the flat phase. A less steep initial ERC phase would protract the transition toward more fully recovered APD and, in fact, may perpetuate electrical alternans. The triphasic ERC time course in normal myocardium cannot be explained by or fitted to single exponentials or single ion channel recovery kinetics. A simple tri-ionic model is suggested that may help explain the shape of the ERC at various repolarization levels and place APD recovery into perspective with intracellular calcium recycling and recovery of contractile force.
1,884
A lazaroid mitigates postresuscitation myocardial dysfunction.
Lazaroids, a series of 21-aminosteroids, reduce free radical mediated injury after ischemia and reperfusion. We hypothesized that the lazaroid U-74389G would minimize postresuscitation myocardial dysfunction and thereby improve neurologically meaningful survival in a rodent model after resuscitation from 8 mins of ventricular fibrillation.</AbstractText>Randomized, controlled laboratory study.</AbstractText>University-affiliated research institute.</AbstractText>Sprague-Dawley rats.</AbstractText>Ventricular fibrillation was electrically induced in ten anesthetized Sprague-Dawley rats. The lazaroid agent U-74389G in a dose of 1 mg.kg-1 or its vehicle serving as a placebo was injected into the right atrium after 7 mins of untreated ventricular fibrillation. One minute after injection of the compound, precordial compression was begun together with mechanical ventilation and continued for 6 mins before attempted electrical defibrillation.</AbstractText>All animals were successfully resuscitated. Postresuscitation cardiac index, left ventricular end-diastolic pressure, the rate of left ventricular pressure increase measured at a left ventricular pressure of 40 mm Hg, and the maximum rate of left ventricular pressure decline were significantly less impaired in lazaroid-treated animals. This contrasted with control animals, which had significantly greater myocardial impairment, greater neurologic deficit, and lesser duration of survival.</AbstractText>The lazaroid compound U-74389G, administered during cardiac arrest, mitigated postresuscitation myocardial dysfunction and improved survival.</AbstractText>
1,885
Ventricular fibrillation scaling exponent can guide timing of defibrillation and other therapies.
The scaling exponent (ScE) of the ventricular fibrillation (VF) waveform correlates with duration of VF and predicts defibrillation outcome. We compared 4 therapeutic approaches to the treatment of VF of various durations.</AbstractText>Seventy-two swine (19.5 to 25.7 kg) were randomly assigned to 1 of 9 groups (n=8 each). VF was induced and left untreated until the ScE reached 1.10, 1.20, 1.30, or 1.40. Animals were treated with either immediate countershock (IC); 3 minutes of CPR before the first countershock (CPR); CPR for 2 minutes, then drugs given with 3 more minutes of CPR before the first shock (CPR-D); or drugs given at the start of CPR with 3 minutes of CPR before the first shock (Drugs+CPR). Return of spontaneous circulation (ROSC) and 1-hour survival were analyzed with chi2 and Kaplan-Meier survival curves. IC was effective when the ScE was low but had decreasing success as the ScE increased. No animals in the 1.30 or 1.40 groups had ROSC from IC (0 of 16). CPR did not improve first shock outcome in the 1.20 CPR group (3 of 8 ROSC). Kaplan-Meier survival analyses indicated that IC significantly delayed time to ROSC in both the 1.3 (P=0.0006) and the 1.4 (P=0.005) groups.</AbstractText>VF of brief to moderate duration is effectively treated by IC. When VF is prolonged, as indicated by an ScE of 1.3 or greater, IC was not effective and delayed time to ROSC. The ScE can help in choosing the first intervention in the treatment of VF.</AbstractText>
1,886
Is systolic blood pressure recovery after exercise a predictor of mortality?
An attenuated systolic blood pressure recovery after exercise has been associated with the severity of atherosclerotic heart disease.</AbstractText>For 6 years, we observed 12,379 patients who underwent symptom-limited exercise testing. We excluded patients receiving antihypertensive medication and patients with valvular disease, emphysema, end-stage renal disease, heart failure, left ventricular systolic dysfunction, and atrial fibrillation. Blood pressure recovery ratio was defined as the ratio of systolic blood pressure at 3 minutes into recovery to systolic blood pressure at peak exercise; this has been shown to correlate with angiographic severity of coronary disease.</AbstractText>The blood pressure recovery ratios ranged from 0.36 to 1.62, with values for increasing quartiles of 0.72 +/- 0.05, 0.82 +/- 0.02, 0.88 +/- 0.02, and 0.99 +/- 0.07. During follow-up, there were 430 deaths (3%). Five-year Kaplan Meier survival rates were 0.975, 0.974, 0.969, and 0.966 in quartiles 1 to 4, respectively. Compared with patients in the lowest quartile of blood pressure recovery ratio, patients in the highest quartile were at somewhat increased risk (hazard ratio, 1.71; 95% CI, 1.31-2.24; P &lt;.001). However, after adjusting for age, sex, body mass index, resting heart rate and blood pressure, peak systolic blood pressure, heart rate recovery, exercise chronotropic response, cardiac history, and standard risk factors, this association was no longer present (adjusted hazard ratio, 1.05; 95% CI, 0.8-1.38; P =.74).</AbstractText>In this low-risk population, abnormal systolic blood pressure recovery after exercise was not independently predictive of mortality after correcting for differences in baseline and exercise characteristics.</AbstractText>
1,887
Physicians' attitudes and the use of oral anticoagulants: surveying the present and envisioning future.
Atrial fibrillation has the highest prevalence in the elderly. While the elderly are at the highest risk for stroke and would benefit the most from anticoagulation, they are also the least likely to receive anticoagulation. In a pooled analysis of the primary prevention trials, warfarin reduced stroke by 68% compared with placebo, and aspirin reduced stroke by 18%. Age, history of hypertension, diabetes, heart failure or reduced left ventricular function, and previous transient ischemic events and stroke are independent risk factors for stroke in patients with atrial fibrillation. Less than 50% of the elderly who have clear-cut indications and no contraindications for warfarin receive anticoagulant therapy. This low use of warfarin is driven by many factors, but physicians' fear of hemorrhage is among the most important. Better adherence to evidence-driven guidelines, better patient and physician education, point-of-care monitoring of INR and the future development of user friendly anticoagulant drugs are likely to result in higher rates of anticoagulation use.
1,888
Sodium-hydrogen exchange inhibition attenuates in vivo porcine myocardial stunning.
Inhibition of the sodium-hydrogen exchanger isoform 1 with HOE-642 (cariporide) has been shown to protect against ischemia-reperfusion injury and to decrease myocardial cell death in numerous animal preparations; however the effects of cariporide in stunned myocardium are not as well understood. We sought to determine whether cariporide attenuated myocardial stunning in vivo.</AbstractText>Open chest anesthetized pigs (22-33 kg) were subjected to 15 min of left anterior descending coronary artery (LAD) occlusion followed by 3 h of reperfusion. Regional ventricular function was assessed by segment shortening. Contractility was measured by stroke work and by load-insensitive preload recruitable stroke work and preload recruitable stroke work area. Vehicle or HOE-642 (1 mg/kg, IV) was administered 10 min before LAD occlusion.</AbstractText>Cariporide treatment significantly improved postischemic segment shortening, stroke work, preload recruitable stroke work, and preload recruitable stroke work area and had no systemic hemodynamic effects. After 3 h of reperfusion, control animals recovered 33% +/- 4% and 33% +/- 3% of preischemic LAD segment shortening and preload recruitable stroke work area values, respectively, whereas animals treated with HOE-642 recovered 59% +/- 6% and 57% +/- 6%, respectively (p &lt; 0.05). Seven (39%) of 17 control animals exhibited ventricular fibrillation during reperfusion; none of the cariporide-treated pigs fibrillated.</AbstractText>Sodium-hydrogen exchange inhibition can attenuate postischemic myocardial stunning in addition to its well-described anti-infarct properties. Inhibition of the sodium-hydrogen exchanger may be beneficial in patients susceptible to postischemic myocardial dysfunction associated with cardiac surgery.</AbstractText>
1,889
Effectiveness of atrial fibrillation surgery in patients with hypertrophic cardiomyopathy.
We report the results of atrial fibrillation surgery in 10 patients with hypertrophic cardiomyopathy, which is the largest case series to date. The Maze procedure, with concomitant septal myectomy if indicated, appears to be feasible in patients with hypertrophic cardiomyopathy and refractory atrial fibrillation.
1,890
Electrocardiologic and echocardiographic features of patients exposed to scorpion bite.
The purpose of this study is to examine clinical progress and hemodynamic and electrocardiologic features (QT depression and heart rate variability [HRV]) of patients exposed to a scorpion bite. Seventeen patients bitten by scorpions, and, as a control group, 15 healthy subjects were included in the study. Standard electrocardiograph (ECG) records, 24-hour Holter-ECG, and Doppler echocardiographic examinations were performed. Holter ECG indicated sinus tachycardia, sinus bradycardia, paroxysmal supraventricular tachycardia, atrial fibrillation, first-degree and second-degree atrioventricular block not requiring treatment, early atrial beats, and early ventricular beats in the patients at frequencies of 82%, 12%, 35%, 12%, 8%, 70%, and 47%, respectively. HRV parameters that reflected parasympathetic activity (SD 35+/-13-43+/-16, RMS-SD: 20+/-9-30+/-12, high frequency: 7.8+/-2-4.3+/-3, p&lt;0.05) were significantly lower (p&lt;0.05). Low frequency, which especially showed sympathetic activity (LF: 11+/-13-11+/-23, p&gt;0.05), was similar in both groups. In addition, the LF/HF ratio, which reflected sympathovagal balance, was significantly increased in the patient group (1.5+/-1-3.0+/-2, p=0.005). Corrected QT and QT dispersion values were not significantly different with respect to the control (p&gt;0.05). In the patient group compared to the control, a significant decrease was determined in the proportion of mitral E velocity to mitral A velocity (mEv/mAv), diastolic filling period (DFP), and left ventricular ejection fraction (LVEF), while a significant increase was noticed in pulmonary artery pressure (PAP) (mEv/mAv: 0.9+/-0.4-1.7+/-0.6, DFP: 362+/-8.5-425+/-89, LVEF: 53.1+/-6.7-68.6+/-5.8, PAP: 38.1+/-13-27.2+/-6, p&lt;0.05). Scorpion bite leads to serious cardiovascular disorders, associated with decreased HRV, decreased systolic and diastolic functions, increased arrhythmic events, and hemodynamic disturbance with sympathetic and parasympathetic balance disturbance.
1,891
Pharmacological modulation of I(Ks): potential for antiarrhythmic therapy.
The slowly (I(Ks)) and rapidly (I(Kr)) activating delayed rectifier K(+) currents play important roles in cardiac ventricular repolarization. Compared with I(Kr), however, I(Ks) has important distinguishing characteristics, including beta-adrenergic receptor stimulation and accumulation at rapid rates that may impart significant therapeutic relevance. Therefore, development of selective I(Ks) inhibitors has been pursued as a strategy for providing potentially safer and more effective Class III antiarrhythmic agents and pharmacological tools for elucidating the normal physiological and potential pathological role of I(Ks) in cardiac repolarization. We have identified a series of 3-Acylamino-1,4 benzodiazepines that are very potent and selective inhibitors of I(Ks). A representative compound, L-768,673 (1) (IC(50)~8nM), has been extensively characterized for its pharmacologic activity. L-768,673 concentration-dependently prolongs action potential duration in a frequency-independent manner in vitro, but decreases transmural dispersion of refractoriness, a risk factor for arrhythmia induction. In conscious dogs, L 768,673 administered IV (0.3-100 micro g/kg) and PO (0.03-1 mg/kg) elicits consistent but limited (5-15%) QT(c) prolongation, and increases ventricular refractory period more at fast than at slow pacing rates, indicating a "forward" rate-dependence in vivo. In an anesthetized canine model of anterior myocardial infarction, I(Ks) blockers suppress the development of ischemic ventricular fibrillation at intravenous doses that minimally prolong the QT interval. I(Ks) blockers display an interesting and intriguing profile of effects on cardiac electrophysiologic parameters that differ in remarkable ways from other selective Class III agents such as I(Kr) blockers. It remains to be determined if these properties can be exploited clinically to provide more effective and safer treatment of cardiac arrhythmias.
1,892
Pharmacological approaches in the treatment of atrial fibrillation.
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is associated with substantial cardiovascular morbidity and mortality. The arrhythmia can be initiated and/or maintained by rapidly firing foci, single- and multiple-circuit reentry. Once initiated, AF alters atrial electrical and structural properties (atrial remodeling) in a way that promotes its own maintenance and recurrence and may alter the response to antiarrhythmic drugs. Thus, initial episodes of paroxysmal (self-terminating) AF lengthens to the point where the arrhythmia becomes persistent (requires cardioversion to restore sinus rhythm) and permanent. AF usually requires a trigger for initiation and a favorable electrophysiological and/or anatomical substrate for maintenance. The substrate includes both cardiovascular (coronary artery disease, valvular heart disease, heart failure, hypertension, dilated cardiomyopathy) and non cardiovascular diseases (thyrotoxicosis, pulmonary diseases). Accordingly, the initial step in patients with AF requires a careful assessment of symptoms and identification of underlying reversible triggers and potentially modifiable underlying structural substrate and treat them aggressively. In contrast to other cardiac arrhythmias, antiarrhythmic drugs (ADs) are the mainstay of therapy. Long-term treatment of AF is directed to restore and maintain the sinus rhythm with class I and III ADs (rhythm-control) or to allow AF to persist and ensure that the ventricular rate is controlled (rate-control) with atrioventricular nodal blocking drugs (digoxin, beta-blockers, verapamil, diltiazem) and prevent thromboembolic complications with anticoagulants. However, the long-term efficacy of ADs for preventing AF recurrence is far from ideal, because of limited efficacy (AF recurs in at least one-half of the patients) and potential side effects, particularly proarrhythmia. Thus, the choice of the appropriate AD will depend on the temporal pattern of the arrhythmia, the presence of associated diseases, easy of administration and adverse effects profile, particularly the risk of proarrhythmia. The recent finding that angiotensin converting enzyme inhibitors and beta-blockers reduce the incidence of AF in patients post myocardial infarction with left ventricular dysfunction confirmed the importance of targeting the underlying arrhythmogenic substrate. This review focuses on the mechanisms underlying AF and the mechanism of action and the efficacy and safety profile of the ADs used in the treatment of atrial fibrillation. The advantages and disadvantages of rhythm and rate control, the role pill in a pocket concept and the role of the new ADs are dicussed.
1,893
Theoretical possibilities for the development of novel antiarrhythmic drugs.
One possible mechanism of action of the available K-channel blocking agents used to treat arrhythmias is to selectively inhibit the HERG plus MIRP channels, which carry the rapid delayed rectifier outward potassium current (I(Kr)). These antiarrhythmics, like sotalol, dofetilide and ibutilide, have been classified as Class III antiarrhythmics. However, in addition to their beneficial effect, they substantially lengthen ventricular repolarization in a reverse-rate dependent manner. This latter effect, in certain situations, can result in life-threatening polymorphic ventricular tachycardia (torsades de pointes). Selective blockers (chromanol 293B, HMR-1556, L-735,821) of the KvLQT1 plus minK channel, which carriy the slow delayed rectifier potassium current (I(Ks)), were also considered to treat arrhythmias, including atrial fibrillation (AF). However, I(Ks) activates slowly and at a more positive voltage than the plateau of the action potential, therefore it remains uncertain how inhibition of this current would result in a therapeutically meaningful repolarization lengthening. The transient outward potassium current (I(to)), which flows through the Kv 4.3 and Kv 4.2 channels, is relatively large in the atrial cells, which suggests that inhibition of this current may cause substantial prolongation of repolarization predominantly in the atria. Although it was reported that some antiarrhythmic drugs (quinidine, disopyramide, flecainide, propafenone, tedisamil) inhibit I(to), no specific blockers for I(to) are currently available. Similarly, no specific inhibitors for the Kir 2.1, 2.2, 2.3 channels, which carry the inward rectifier potassium current (I(kl)), have been developed making difficult to judge the possible beneficial effects of such drugs in both ventricular arrhythmias and AF. Recently, a specific potassium channel (Kv 1.5 channel) has been described in human atrium, which carries the ultrarapid, delayed rectifier potassium current (I(Kur)). The presence of this current has not been observed in the ventricular muscle, which raises the possibility that by specific inhibition of this channel, atrial repolarization can be lengthened without similar effect in the ventricle. Therefore, AF could be terminated and torsades de pointes arrhythmia avoided. Several compounds were reported to inhibit I(Kur)(flecainide, tedisamil, perhexiline, quinidine, ambasilide, AVE 0118), but none of them can be considered as specific for Kv 1.5 channels. Similarly to Kv 1.5 channels, acetylcholine activated potassium channels carry repolarizing current (I(KAch)) in the atria and not in the ventricle during normal vagal tone and after parasympathetic activation. Specific blockers of I(KAch) can, therefore, also be a possible candidate to treat AF without imposing proarrhythmic risk on the ventricle. At present several compounds (amiodarone, dronedarone, aprindine, pirmenol, SD 3212) were shown to inhibit I(KAch) but none of them proved to be selective. Further research is needed to develop specific K-channel blockers, such as I(Kur)and I(KAch) inhibitors, and to establish their possible therapeutic value.
1,894
Influence of nonexcitable cells on spiral breakup in two-dimensional and three-dimensional excitable media.
We study spiral wave dynamics in the presence of nonexcitable cells in two-dimensional (2D) and three-dimensional (3D) excitable media, described by the Aliev-Panfilov model. We find that increasing the percentage of randomly distributed nonexcitable cells can prevent the breaking up of a spiral wave into a complex spatiotemporal pattern. We show that this effect is more pronounced in 2D than 3D excitable media. We explain the observed 2D vs 3D differences by a different dependence of the period and diastolic interval of the spiral wave on the percentage of nonexcitable cells in 2D and 3D excitable media.
1,895
Unusual response to the ajmaline test in a patient with Brugada syndrome.
We present a Brugada syndrome patient who suffered an aborted sudden death. The ajmaline test (1 mg/kg body weight) induced accentuated alternans ST-segment elevation in V1-V2 without ventricular arrhythmias. It could represent silent ischaemia not detected before, failure of myocardial regions to repolarize in alternate beats due to transmural dispersion of conduction and refractoriness in the right ventricular outflow tract or a rate dependent sodium channel block by ajmaline. We need more studies to know whether this electrocardiographic sign is a risk factor for life-threatening ventricular arrhythmias in Brugada syndrome patients.
1,896
[Postpartum cardiomyopathy revealed by acute lower limb ischemia].
Peripartum cardiomyopathy is an uncommon disease defined as a dilated cardiomyopathy during puerperium, with left ventricular dysfunction (ejection fraction &lt; 45%) without any other etiology. The etiology of this disease remains uncertain and it can be revealed in a variety of ways. Thrombo-embolic complications may be, although infrequently, the initial manifestation of peripartum cardiomyopathy, which is usually an intracardiac thrombosis. Lower extremity embolism is uncommon. The case reported is about a 39-year-old woman, multiparous, who presented, 40 days after delivery, a global heart failure with atrial fibrillation, revealed by left lower extremity thromboembolism. After echocardiographic and etiologic examinations, the diagnosis was established as peripartum cardiomyopathy. It evolved favourably after 2 months of medical treatment: the symptoms and cardiomegaly decreased, left ventricular systolic function was improved.
1,897
[Ventricular fibrillation induction by transesophageal stimulation in a patient with valvular heart disease].
Rapid atrial transesophageal stimulation is currently used to stop atrial flutter or tachycardia. We report a case complicated of ventricular fibrillation. It is possible to pace the ventricles by transesophageal stimulation in 2-10% of cases. The ventricular stimulation might be dangerous in patients with heart disease. Therefore, transesophageal stimulation must be performed in specialized environment.
1,898
Late incidence and predictors of persistent or recurrent heart failure in patients with aortic prosthetic valves.
We examined factors associated with persistent or recurrent congestive heart failure after aortic valve replacement.</AbstractText>Patients who underwent aortic valve replacement with contemporary prostheses (n = 1563) were followed up with annual clinical assessment and echocardiography. The effect of demographic, comorbid, and valve-related variables on the composite outcome of New York Heart Association class III or IV symptoms or congestive heart failure death after surgery was evaluated with stratified log-rank tests, Cox proportional hazard models, and logistic regression. Factors associated with all-cause death were also examined. Prediction models were bootstrapped 1000 times.</AbstractText>Total follow-up was 6768 patient-years (mean, 4.3 +/- 3.3 years; range, 60 days to 17.1 years). Freedom from congestive heart failure or congestive heart failure death was 98.6% +/- 0.3%, 88.6% +/- 1.0%, 73.9% +/- 2.3%, and 45.2% +/- 8.5% at 1, 5, 10, and 15 years, respectively. Age, preoperative New York Heart Association class, left ventricular grade, atrial fibrillation, coronary artery disease, smoking, and redo status predicted congestive heart failure after surgery (all P &lt;.05). Larger prosthesis size and effective orifice area, both absolute and indexed for body surface area, were independently associated with freedom from congestive heart failure. Increased transprosthesis gradients were predicted by prosthesis-patient mismatch and were associated with congestive heart failure after surgery. Mismatch defined as an effective orifice area/body surface area of 0.80 cm(2)/m(2) or less was a significant predictor of congestive heart failure events after surgery, but mismatch defined as an effective orifice area/body surface area of 0.85 cm(2)/m(2) or less was not. Small prosthesis size and mismatch were not significantly associated with all-cause mortality.</AbstractText>These analyses identify independent predictors of congestive heart failure symptoms and congestive heart failure death late after aortic valve replacement and indicate that prosthesis size has a significant effect on this cardiac end point, but not on overall survival after aortic valve replacement.</AbstractText>
1,899
Predictors of delirium after cardiac surgery delirium: effect of beating-heart (off-pump) surgery.
Despite improved outcomes after cardiac operations, postoperative delirium remains a common complication that is associated with increased morbidity and prolonged hospital stay.</AbstractText>Univariate and multivariate predictors of postoperative delirium were determined from prospectively gathered data on 16,184 patients undergoing cardiac operations with cardiopulmonary bypass (conventional, n = 14,342) and without cardiopulmonary bypass (beating-heart surgery, n = 1847) between April 1996 and August 2001. Delirium was defined as a transient mental syndrome of acute onset characterized by global impairment of cognitive functions, a reduced level of consciousness, attentional abnormalities, increased or decreased psychomotor activity, and a disordered sleep-wake cycle.</AbstractText>The overall prevalence of postoperative delirium was 8.4%. Of 49 selected patient-related risk factors and treatment variables, 35 were highly associated with postoperative delirium by univariate analysis. Stepwise logistic regression revealed the following variables as independent predictors of delirium: history of cerebrovascular disease, peripheral vascular disease, atrial fibrillation, diabetes mellitus, left ventricular ejection fraction of 30% or less, preoperative cardiogenic shock, urgent operation, intraoperative hemofiltration, operation time of 3 hours or more, and a high perioperative transfusion requirement. Two variables were identified as having a significant protective effect against postoperative delirium: beating-heart surgery and younger patient age.</AbstractText>Postoperative delirium is a common complication in cardiac operations. The increased use of beating-heart surgery without cardiopulmonary bypass may lead to a lower prevalence of this complication and thus improve patient outcomes.</AbstractText>