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6,300 | Pharmacological modifications of the stretch-induced effects on ventricular fibrillation in perfused rabbit hearts. | Stretch induces modifications in myocardial electrical and mechanical activity. Besides the effects of substances that block the stretch-activated channels, other substances could modulate the effects of stretch through different mechanisms that affect Ca(2+) handling by myocytes. Thirty-six Langendorff-perfused rabbit hearts were used to analyze the effects of the Na(+)/Ca(2+) exchanger blocker KB-R7943, propranolol, and the adenosine A(2) receptor antagonist SCH-58261 on the acceleration of ventricular fibrillation (VF) produced by acute myocardial stretching. VF recordings were obtained with two epicardial multiple electrodes before, during, and after local stretching in four experimental series: control (n = 9), KB-R7943 (1 microM, n = 9), propranolol (1 microM, n = 9), and SCH-58261 (1 microM, n = 9). Both the Na(+)/Ca(2+) exchanger blocker KB-R7943 and propranolol induced a significant reduction (P < 0.001 and P < 0.05, respectively) in the dominant frequency increments produced by stretching with respect to the control and SCH-58261 series (control = 49.9%, SCH-58261 = 52.1%, KB-R7943 = 9.5%, and propranolol = 12.5%). The median of the activation intervals, the functional refractory period, and the wavelength of the activation process during VF decreased significantly under stretch in the control and SCH-58261 series, whereas no significant variations were observed in the propranolol and KB-R7943 series, with the exception of a slight but significant decrease in the median of the fibrillation intervals in the KB-R7943 series. KB-R7943 and propranolol induced a significant reduction in the activation maps complexity increment produced by stretch with respect to the control and SCH-58261 series. In conclusion, the electrophysiological effects responsible for stretch-induced VF acceleration in the rabbit heart are reduced by the Na(+)/Ca(2+) exchanger blocker KB-R7943 and by propranolol but not by the adenosine A(2) receptor antagonist SCH-58261. |
6,301 | Specificities of atrial electrophysiology: Clues to a better understanding of cardiac function and the mechanisms of arrhythmias. | The electrical properties of the atria and ventricles differ in several aspects reflecting the distinct role of the atria in cardiac physiology. The study of atrial electrophysiology had greatly contributed to the understanding of the mechanisms of atrial fibrillation (AF). Only the atrial L-type calcium current is regulated by serotonine or, under basal condition, by phosphodiesterases. These distinct regulations can contribute to I(Ca) down-regulation observed during AF, which is an important determinant of action potential refractory period shortening. The voltage-gated potassium current, I(Kur), has a prominent role in the repolarization of the atrial but not ventricular AP. In many species, this current is based on the functional expression of K(V)1.5 channels, which might represent a specific therapeutic target for AF. Mechanisms regulating the trafficking of K(V)1.5 channels to the plasma membrane are being actively investigated. The resting potential of atrial myocytes is maintained by various inward rectifier currents which differ with ventricle currents by a reduced density of I(K1), the presence of a constitutively active I(KACh) and distinct regulation of I(KATP). Stretch-sensitive or mechanosensitive ion channels are particularly active in atrial myocytes and are involved in the secretion of the natriuretic peptide. Integration of knowledge on electrical properties of atrial myocytes in comprehensive schemas is now necessary for a better understanding of the physiology of atria and the mechanisms of AF. |
6,302 | Supraventricular arrhythmia induction by an implantable cardioverter defibrillator in a patient with hypertrophic cardiomyopathy. | A 23-year-old woman with obstructive hypertrophic cardiomyopathy and history of frequent unexplained syncope had undergone implantable cardioverter defibrillator implantation. She had experienced frequent inappropriate shocks since implantation due to T-wave oversensing. After one of the syncopal attacks, she was found to have an atrioventricular (AV)-reentrant tachycardia, induced by a high-voltage shock, with rapid degeneration to atrial fibrillation and then ventricular fibrillation. The AV-reentrant tachycardia was believed to be the cause of both syncopal attacks and inappropriate shocks. The patient has been asymptomatic after ablation of the accessory pathway. To the best of our knowledge, this is the first report of induction of an AV-reentrant tachycardia by a high-voltage implantable cardioverter defibrillator shock. |
6,303 | Ventricular fibrillation as the presenting manifestation of adrenocortical carcinoma. | We describe a case of a young adult in whom sudden cardiac death due to ventricular fibrillation was the presenting manifestation of an adrenocortical carcinoma. The arrhythmia was precipitated by severe hypokalemia induced by the aldosterone-secreting tumor. Sudden death has not been previously described as a manifestation of this adrenal neoplasm. Unexplained persistent hypokalemia after resuscitated sudden death (especially when combined with hypertension( should prompt investigation for an underlying secondary hypertension, particularly adrenal pathology. Adrenocortical carcinoma should be considered in the differential diagnosis of unexplained sudden death associated with unexplained hypokalemia. |
6,304 | CMR findings in patients with hypertrophic cardiomyopathy and atrial fibrillation. | We sought to evaluate the relation between atrial fibrillation (AF) and the extent of myocardial scarring together with left ventricular (LV) and atrial parameters assessed by late gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) in patients with hypertrophic cardiomyopathy (HCM).</AbstractText>AF is the most common arrhythmia in HCM. Myocardial scarring is also identified frequently in HCM. However, the impact of myocardial scarring assessed by LGE CMR on the presence of AF has not been evaluated yet.</AbstractText>87 HCM patients underwent LGE CMR, echocardiography and regular ECG recordings. LV function, volumes, myocardial thickness, left atrial (LA) volume and the extent of LGE, were assessed using CMR and correlated to AF. Additionally, the presence of diastolic dysfunction and mitral regurgitation were obtained by echocardiography and also correlated to AF.</AbstractText>Episodes of AF were documented in 37 patients (42%). Indexed LV volumes and mass were comparable between HCM patients with and without AF. However, indexed LA volume was significantly higher in HCM patients with AF than in HCM patients without AF (68 +/- 24 ml.m-2 versus 46 +/- 18 ml.m-2, p = 0.0002, respectively). The mean extent of LGE was higher in HCM patients with AF than those without AF (12.4 +/- 14.5% versus 6.0 +/- 8.6%, p = 0.02). When adjusting for age, gender and LV mass, LGE and indexed LA volume significantly correlated to AF (r = 0.34, p = 0.02 and r = 0.42, p < 0.001 respectively). By echocardiographic examination, LV diastolic dysfunction was evident in 35 (40%) patients. Mitral regurgitation greater than II was observed in 12 patients (14%). Multivariate analysis demonstrated that LA volume and presence of diastolic dysfunction were the only independent determinant of AF in HCM patients (p = 0.006, p = 0.01 respectively). Receiver operating characteristic curve analysis indicated good predictive performance of LA volume and LGE (AUC = 0.74 and 0.64 respectively) with respect to AF.</AbstractText>HCM patients with AF display significantly more LGE than HCM patients without AF. However, the extent of LGE is inferior to the LA size for predicting AF prevalence. LA dilation is the strongest determinant of AF in HCM patients, and is related to the extent of LGE in the LV, irrespective of LV mass.</AbstractText> |
6,305 | B-type natriuretic peptide is predictive of hospitalization in community-dwelling elderly without heart diseases. | To examine prospectively the relationship between plasma B-type natriuretic peptide (BNP) levels in community-dwelling elderly and their hospitalization.</AbstractText>A total number of 644 subjects aged 65 years or older were recruited from the annual community health examinations. Those with a history of stroke or neurological findings were not included. After excluding those with old myocardial infarction, left ventricular dysfunction, moderate or severe valvular disorders, atrial fibrillation, renal insufficiency, and history of hospitalization within 1 year, 602 participants (226 men, 376 women; mean age, 80.3 +/- 6.2 years) remained eligible for this study. Antihypertensive medications, activities of daily living (ADL) score and history of hospitalization were assessed by annual interview. Measurement of casual blood pressure, Mini-Mental State Examination, electrocardiography and echocardiography were performed. Plasma BNP, serum creatinine, total cholesterol, albumin and hemoglobin A1c levels were also examined. A follow-up survey was performed for the occurrence and reasons for hospitalization.</AbstractText>During a median follow up of 37 months, 112 subjects were hospitalized. After adjustment for conventional risk factors of hospitalization using the Cox proportional hazard model, each increment of 1 standard deviation in log BNP levels was associated with a 36% increase in the risk of hospitalization (P = 0.02). Plasma BNP levels were significantly higher in the hospitalized subjects due to stroke, heart diseases, dementia, pneumonia and also difficulty to live alone than those of the subjects without hospitalization.</AbstractText>Plasma BNP level is a very useful biochemical marker predictive of future hospitalization in community-dwelling independent elderly people without apparent heart diseases.</AbstractText> |
6,306 | A smart method of intraoperative explantation of an aortic bioprosthesis. | Structural prosthetic valve deterioration and nonstructural dysfunction are two common causes of nonfatal valve events following implantation of a bioprosthetic valve. Using caution and skill, implantation of a bioprosthesis is relatively easy. On the other hand, explantation of a bioprosthesis is a challenging and time-consuming procedure. We have developed a surgical technique by which we were able to ameliorate this troublesome situation in a 79-year-old man with aortic stenosis in whom we had to intraoperatively explant the bioprosthesis that we have put in initially. Another bioprosthesis of the same kind was used to replace the old prosthesis with the rest of his postoperative course until dismissal being eventless. |
6,307 | Impact of apex-sparing partial left ventriculectomy on left ventricular geometry, function, and long-term survival of patients with end-stage dilated cardiomyopathy. | Currently, partial left ventriculectomy (PLV) has not been widely accepted as a treatment option for dilated cardiomyopathy (DCM) because its results thus far have been inconsistent. In an animal study, apex-sparing PLV (AS-PLV) was shown to produce greater improvement in left ventricle (LV) function than conventional PLV in which the apex was removed. The aim of this study is to investigate the effectiveness of AS-PLV in a clinical setting.</AbstractText>From September 1999 to December 2007, 13 patients with DCM underwent AS-PLV. Left ventriculotomy was made in the thinnest portion of the lateral wall without injuring the apex, the papillary muscles, and the circumflex coronary artery, which supplies the neighboring myocardium.</AbstractText>All patients were discharged from the hospital, except for one patient who developed refractory ventricular fibrillation on postoperative day 35. After AS-PLV, the LV diastolic dimension decreased from 71 +/- 10 mm to 55 +/- 9 mm; LV ejection fraction (EF) from 28%+/- 8% to 39%+/- 11%; and New York Heart Association (NYHA) class from 3 +/- 1.7 to 1.5 +/- 0.6; the differences were significant (p < 0.01). LV function and geometry remained unchanged 2 years after AS-PLV with LVDD of 60 +/- 7 mm, LVEF of 34%+/- 8%, and NYHA class of 1.7 +/- 0.6, respectively (N.S vs. at discharge).</AbstractText>Regardless of the etiology of LV dilatation, AS-PLV restored the ellipsoidal shape of the LV and improved LV function. AS-PLV is a feasible option for treating diseased LVs with lateral wall lesions.</AbstractText> |
6,308 | The spectrum of long-term electrophysiologic abnormalities in patients with univentricular hearts. | Patients with univentricular hearts experience a wide range of electrophysiolgic abnormalities which tend to develop years after cardiovascular surgical interventions. Intra-atrial reentrant tachycardia (atrial flutter) in the Fontan population is the most common arrhythmia and, as such, has the largest body of literature addressing its cause and treatment. However, sinus node dysfunction, other atrial arrhythmias, ventricular arrhythmias, and cardiac dysynchrony also occur in this patient population. The purpose of this article is to review the prevalence, mechanisms, and treatment of these electrophysiologic abnormalities within the single ventricle and Fontan patient. |
6,309 | [The influence of radiofrequency (RF) ablation of the atrioventricular junction in atrial fibrillation on left ventricular systolic function, exercise tolerance and quality of life]. | In patients with drug refractory atrial fibrillation radiofrequency (RF), ablation of the atrioventricular (AV) junction and pacemaker implantation is an alternative procedure. The aim of this study was to assess the left ventricular systolic function, exercise tolerance and quality of life (QOL) in patients who underwent RF AV junction ablation and permanent pacemaker implantation.</AbstractText>24 patients (14 male, 10 female, 64.8 +/- 11.0 years) underwent RF ablation. The duration of symptoms was 4 +/- 1.9 years prior to ablation. Post ablation, the selected pacing mode was DDDR for the 4 patients with paroxysmal AF and VVIR for the 20 patients with chronic AF. The underlying heart disease was coronary artery disease (17 CAD), arterial hypertension (15 AH) and heart failure (9 HF). Prior to the ablation and after 6 months follow-up--an ECHO, exercise tolerance (the six minute walk -M6) and QOL assessment (the questionnaire of SF-36, functional symptomatology scale, DASI scale) were performed. The NYHA class was also evaluated.</AbstractText>The patients showed a significant improvement in NYHA class (p < 0.005), in QOL (SF-36, p < 0.0025; symptomatic score, p < 0.025; DASI, p < 0.01) and in the M6 (p < 0.01). We did not find significant changes in left ventricular performance. The significant correlation was observed between the SF-36 and functional symptomatology (r = 0.71) and DASI (r = 0.53). We divided our patients into two groups: Group A (patients with the higher NYHA class, p < 0.025) with significant improvement QOL and Group B with insignificant improvement of QOL. Post ablation in group A we--observed significant improvement in NYHA class and M6 (p < 0.01).</AbstractText>1. In patients with drug refractory atrial fibrillation, RF AV junction ablation and permanent pacemaker implantation significantly improve the QOL, M6 and NYHA class. 2. Significant improvement of QOL as well as in M6 can be expected after RF ablation with pacemaker implantation, especially in patients with more advanced hart failure (higher NYHA class).</AbstractText> |
6,310 | Emergency Medical System response to out-of-hospital cardiac arrest in Milan, Italy. | The objective of this study was to investigate how rapidly the Emergency Medical System provides life support to patients suffering out-of-hospital cardiac arrest in Milan, Italy. The study population included 1426 consecutive participants with out-of-hospital cardiac arrest between January 2007 and October 2008. The mean age was 72.7 years. The incidence of ventricular tachycardia/ventricular fibrillation as the presenting rhythm was 12.7%. Eighty percent of out-of-hospital cardiac arrests occurred at home and bystander cardiopulmonary resuscitation (CPR) was in progress in 11.1% of all cases. The mean time interval from collapse-to-first shock was 18.67+/-5.37 min. The mean Emergency Medical System unit response time interval was 7.07+/-3.14 min; time elapsed from arrival-to-first CPR was 7.75+/-4.32 min. In conclusions, the dispatch to arrival and dispatch to CPR intervals are comparable with those reported in other large urban areas, but the time from arrival-to-first CPR was longer than recommended by current guidelines. |
6,311 | Pulse variations of a conducted energy weapon (similar to the TASER X26 device): effects on muscle contraction and threshold for ventricular fibrillation*. | Conducted energy weapons (such as the Advanced TASER X26 model produced by TASER International), incapacitate individuals by causing muscle contractions. To provide information relevant to development of future potential devices, a "Modifiable Electronic Stimulator" was used to evaluate the effects of changing various parameters of the stimulating pulse. Muscle contraction was affected by pulse power, net/gross charge, pulse duration, and pulse repetition frequency. The contraction force increased linearly as each of these factors was increased. Elimination of a precursor pulse from X26-like pulses did not have a significant effect on the normalized force measured. Muscle-contraction force increased as the spacing increased from 5 to 20 cm, with no further change in force above 20 cm of spacing. Therefore, it is suggested that any future developments of new conducted energy weapons should include placement of electrodes a minimum of 20 cm apart so that efficiency of the system is not degraded. In the current study, the 50% probability of fibrillation level of X26-like pulses ranged from 4 to 5 times higher than the X26 itself. Relatively large variations about the X26 operating level were found not to result in fibrillation or asystole. Therefore, it should be possible to design and build an X26-type device that operates efficiently at levels higher than the X26. |
6,312 | Surface vs. aortic flush cooling during cardiac arrest in pigs. | To investigate the feasibility and efficacy of earlier induction of hypothermia already during the 'no-flow' period of cardiac arrest with non-invasive surface cooling or invasive aortic flush cooling.</AbstractText>This was a prospective randomized experimental study that included 14 pigs, Large White breed (30-38 kg), with ventricular fibrillation cardiac arrest plus blanket surface and an invasive cold saline flush cooling. The endpoint was a decline in brain temperature (T(br)) at 35 min after cardiac arrest.</AbstractText>With surface cooling, T(br) decreased from 38.7+/-0.2 degrees C to 37.4+/-0.8 degrees C (P=0.02) and with invasive cooling T(br) decreased from 38.8+/-0.13 degrees C to 19.0+/-2.8 degrees C within 216+/-23 s (P=0.02) and increased back to 33.0+/-0.6 degrees C at 35 min of cardiac arrest (P=0.02 vs. T(br) at 15 min, P=0.002 vs. T(br) at 35 min in the surface cooling groups).</AbstractText>Invasive cooling by aortic flush with cold saline rapidly induces deep cerebral hypothermia, whereas non-invasive surface cooling only marginally decreases brain temperature.</AbstractText> |
6,313 | Prevention of sudden cardiac death: return to sport considerations in athletes with identified cardiovascular abnormalities. | Sudden cardiac death in the athlete is uncommon but extremely visible. In athletes under age 30, genetic heart disease, including hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and ion channel disorders account for the majority of the deaths. Commotio cordis, involving blunt trauma to the chest leading to ventricular fibrillation, is also a leading cause of sudden cardiac death in young athletes. As the athlete ages, coronary atherosclerosis contributes to an increasing incidence of sudden death during sporting activities. For athletes with aborted sudden death or arrhythmia-related syncope, an implantable cardioverter defibrillator is generally indicated, and they should be restricted from most competitive sports. Participation in competitive athletics for athletes with heart disease should generally follow the recently published 36th Bethesda Conference Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities. |
6,314 | Incidence and aetiology of sudden cardiac death in young athletes: an international perspective. | The incidence of sudden cardiac death (SCD) among young athletes is estimated to be 1-3 per 100,000 person years, and may be underestimated. The risk of SCD in athletes is higher than in non-athletes because of several factors associated with sports activity that increase the risk in people with an underlying cardiovascular abnormality. A clear gender difference in the incidence of SCD exists in young athletes, with the risk in male athletes being up to 9 times higher than in female athletes. The most common causes of SCD in young athletes is underlying inherited/congenital cardiac disease, such as cardiomyopathies, congenital coronary anomalies and ion channelopathies. Blunt chest trauma also may cause ventricular fibrillation in a structurally normal heart, known as commotio cordis. Although geographical differences in the causes of SCD in young athletes have been reported, these disparities are more likely to be related to the type and implementation of pre-participation screening leading to the identification of athletes at risk, rather than reflecting a truly different ethiology. More studies are needed to clarify the role of ethnicity in the prevalence of diseases known to cause SCD in young athletes. |
6,315 | Right ventricular apical lead position is associated with prolonged signal-averaged P-wave duration. | The study aimed to determine if right ventricular apical pacing is associated with adverse change in atrial substrate compared with right ventricular septal pacing.</AbstractText>Patients with septal leads and dual-chamber devices with more than 3 months of follow-up and 70% or higher cumulative percentage of ventricular pacing were compared with a matched group of apically implanted leads with a cumulative percentage ventricular pacing of 70% or higher. Device parameters were recorded, and high-resolution recordings were obtained for signal-averaged P-wave (SAPW) analysis. Previously obtained SAPW recordings taken from 49 healthy patients and 73 patients with paroxysmal atrial fibrillation were used as negative and positive controls, respectively.</AbstractText>Ten patients with septal leads (mean age, 71.9 +/- 12.1 years; mean months implanted, 10.5 +/- 3.2 months) and 9 patients with apical leads (mean age, 71.9 +/- 5.7 years; mean months implanted, 11.4 +/- 6.4 months) were enrolled. The SAPW duration was longer in the apical cohort compared with the septal cohort (144.8 +/- 6.9 and 133.0 +/- 5.5 milliseconds, respectively; P = .001), whereas there was no significant difference between septal and normal cohorts (133.0 +/- 5.5 and 129.3 +/- 7.1 milliseconds, respectively; P = .08).</AbstractText>Apical pacing is associated with prolonged P-wave duration relative to septal pacing and controls: this may manifest as increased risk of atrial tachycardias and presents a potentially novel benefit of septal pacing.</AbstractText> |
6,316 | ECG-voltage in alcoholics and non-alcoholics with acute alcohol intoxication. | Alcohol intoxication is probably the most common intoxication worldwide, and may be lethal. The exact mechanism by which ethanol intoxication contributes to death is unknown, although ventricular tachyarrhythmias degenerating into fibrillation is a possible cause. Alcoholics have increased risk of sudden death and, possibly, higher risk than occasional drinkers. In 32 consecutive patients with alcohol intoxication Delta-voltage was the differences in voltage between values at admission (when patients had high blood alcohol levels) and at discharge (when the patients were assumed sober), and was calculated for QRS complexes and T-waves in precordial and bipolar leads. Delta-precordial-QRS-voltage was positive in 13/15 (87%, p=0.010) of the occasional drinkers and in 8/17 (47%, p=0.53) of the alcoholics (alcoholics vs. occasional drinkers: p=0.008). Both Delta-precordial-QRS-voltage and Delta-precordial-T-wave-voltage differed from the group of occasional drinkers to the group of alcoholics, after adjusting for age, sex and s-osmolality. Mean alcohol concentration was 0.29%. Conclusions have to be made with caution. Alcohol in potential lethal blood concentrations seems to increase ECG-voltages in occasional drinkers but not in alcoholics. This indicates that alcohol interferes with the ion channels that create the action potentials of the heart, but in alcoholics an adaptation process has occurred. |
6,317 | Hypothermia after cardiac arrest. | Mild therapeutic hypothermia (32 degrees C-34 degrees C) is the only therapy that improved neurological outcome after cardiac arrest in a randomized, controlled trial. Induced hypothermia after successful resuscitation leads to one additional patient with intact neurological outcome for every 6 patients treated. It protects the brain after ischemia by reduction of brain metabolism, attenuation of reactive oxygen species formation, inhibition of excitatory amino acid release, attenuation of the immune response during reperfusion, and inhibition of apoptosis. Potential side effects such as infections have to be kept in mind and treated accordingly. Mild hypothermia is a safe and effective therapy after cardiac arrest, even in hemodynamically compromised patients and in patients undergoing percutaneous coronary intervention. Its use is recommended by the American Heart Association and the International Liaison Committee on Resuscitation for unconscious adult patients with spontaneous circulation after out-of-hospital ventricular fibrillation cardiac arrest. Further research is needed to maximize its potential benefits. |
6,318 | A rare connection: fasciculoventricular pathway in PRKAG2 disease. | Mutations in the PRKAG2 gene that regulates the gamma 2 subunit of the AMP-dependent protein kinase A have been associated with the development of AV accessory pathways, cardiac hypertrophy, and conduction system abnormalities. The accessory pathways described in PRKAG2 disease have mostly been AV bypass tracts, as mutations in the PRKAG2 gene disrupt the normal AV junction development. There have also been a few reports of nodoventricular tracts associated with PRKAG2 mutations, as these tracts also involve the AV junction. We describe a case of a fasciculoventricular pathway with PRKAG2 mutation suggesting a more widespread involvement of the PRKAG2 gene in the development of the cardiac conduction system. |
6,319 | The effect of the preshock pause on coronary perfusion pressure decay and rescue shock outcome in porcine ventricular fibrillation. | We sought to determine the effect of the preshock pause (PSP) on coronary perfusion pressure (CPP) decay and subsequent rescue shock (RS) outcome in porcine ventricular fibrillation (VF).</AbstractText>Retrospective analysis of digitally recorded CPP tracings was performed. Ventricular fibrillation was electrically induced in all animals and resuscitation was standardized in all experiments. The first RS was delivered after an average of 10.8 minutes of VF (7.4 minutes of nontreatment and 3.4 minutes of resuscitation). The continuous CPP tracing segments, during the hands-off period prior to the first two rescue shocks, were imported into a spreadsheet and analyzed using descriptive statistics as well as univariate and multivariate statistical methods. The RS outcome for each animal was recorded as failed or return of spontaneous circulation (ROSC) (a systolic blood pressure of 80 mmHg or greater, sustained continuously for at least 1 minute).</AbstractText>We included 196 rescue shocks (120 first RS [RS1], 76 second RS [RS2]) from 120 swine. The mean CPP following the last compression before RS was 23.4 mmHg (standard error of the mean [SEM]: 1.3). The median PSP duration was 4.1 seconds (interquartile range [IQR]: 3.3, 6.1). The mean CPP just prior to RS was 7.6 mmHg (SEM: 0.6). Overall, the RS was successful (ROSC) in 57 of 120 (0.47 [95% confidence interval (CI): 0.38, 0.56]) attempts. Univariate results showed a counterintuitive positive correlation between PSP and maximum CPP for RS1 (r = 0.548, p < 0.001).</AbstractText>During the resuscitation PSP in these porcine studies of prolonged VF, CPP dropped precipitously, but RS outcome was not adversely affected.</AbstractText> |
6,320 | Impact of the 2005 American Heart Association cardiopulmonary resuscitation and emergency cardiovascular care guidelines on out-of-hospital cardiac arrest survival. | To describe changes in out-of-hospital cardiac arrest (OOHCA) survival before and after the release of the 2005 American Heart Association (AHA) guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC).</AbstractText>Data were extracted from an OOHCA registry for 1,681 adult cases of cardiac arrest treated by one emergency medical services (EMS) system between April 1, 2004, and December 31, 2007, in a large city (2005 population 730,657). The primary endpoint was survival to hospital discharge. A convenience sample of 69 electronic electrocardiogram (ECG) recordings was reviewed to assess CPR quality parameters using impedance waveform analysis during corresponding time periods. Intervention. Implementation of the 2005 AHA guidelines for CPR and ECC in spring 2006.</AbstractText>The annual treated OOHCA incidence rate was 68/100,000; and the treated ventricular fibrillation (VF) incidence rate was 15/100,000. Bystanders performed CPR in 28% of cases. Public automated external defibrillator (AED) use was < 2% over the entire study, and few patients received hypothermia therapy. Unadjusted OOHCA survival rates were significantly higher in the postguidelines period at 9.4% (n = 1,021) than in the preguidelines period at 6.1% (n = 660), despite similarities in all major predictors of outcome (odds ratio [OR] 1.6; 95% confidence interval [CI] 1.1 to 2.4). Bystander-witnessed OOHCA survival for victims in VF on EMS arrival was 19 of 78 (24%) in the preguidelines period versus 34 of 112 (30%) in the postguidelines period (OR 1.4; 95% CI 0.7 to 2.6). CPR quality measures showed significant improvement in the postguidelines period. The mean no-flow fraction in the preguidelines group was 0.46 and dropped to 0.34 in the postguidelines group, a difference of 0.12 (95% CI 0.05 to 0.19). Multivariate regression analysis adjusting for significant predictors of survival showed that OOHCA in the postguidelines period was associated with 1.8 greater odds of survival than in the preguidelines period (95% CI 1.2 to 2.7).</AbstractText>In this large city, substantial improvement occurred in overall OOHCA survival rates following the implementation of the 2005 AHA guidelines for CPR and ECC. These changes were associated with improvements in the quality of CPR.</AbstractText> |
6,321 | [Optimized CRT programming: relevance and practical application]. | Cardiac resynchronization therapy (CRT) can result in significant clinical improvement in patients with congestive heart failure. Non-response to CRT might be attributable to suboptimal programming. Follow-up has to ensure effective left ventricular (LV) stimulation at rest and also sufficient exercise-dependent atrial rates. Rate adaptive pacing is required in case of chronotropic incompetence. Specific algorithms may help to restore biventricular pacing or the enhance biventricular pacing rate when intrinsic AV conduction occurs, e.g., during intermittent atrial fibrillation. An individual adaptation of the AV interval is essential to achieve maximal benefit from resynchronization. Optimized AV interval programming synchronizes atrial and ventricular contraction, maximizing the atrial contribution to LV diastolic filling and preventing presystolic mitral regurgitation. Interventricular synchrony and LV contraction might be further harmonized by VV interval adaptation, although the impact of VV optimization on CRT outcome is still under debate. Non-invasive methods of AV and VV interval optimization by electro- and echocardiography are discussed. |
6,322 | Myotonic dystrophy as a potential killer. | A 19-year-old man suffered a cardiac arrest during a promenade with his friends. Cardiac resuscitation was started immediately. Anamnesis uncovered that the father as well as a cousin of the patient suffered from myotonic dystrophy (MD). Follow-up ECG monitoring showed intercurrent III degree AV-block as well as several asymptomatic episodes of ventricular tachycardias, atrial flutter with changing conduction and atrial fibrillation. Neuromuscular testing and genetic analyses confirmed the diagnosis of a myotonic dystrophy. Myotonic dystrophy (MD) is a chronic, slowly progressing, autosomal dominant inherited multisystemic disease.The clinical presentation is characterized by wasting of the muscles with delayed relaxation, cataracts and endocrine changes. MD is associated with both cardiac conduction disturbances and structural heart abnormalities. Electrocardiographic abnormalities include conduction disturbances or tachyarrhythmias. This case illustrates that potentially lethal arrhythmias inducing sudden cardiac death may occur in MD patients even in the absence of neurologic symptoms characterizing the systemic illness. |
6,323 | Effects of intravenous nifekalant as a lifesaving drug for severe ventricular tachyarrhythmias complicating acute coronary syndrome. | Intravenous amiodarone (AMD) has been used for the treatment of ventricular tachycardia/fibrillation (VT/VF) in emergency care medicine. However, AMD acts slowly and is occasionally accompanied by hypotension and bradycardia. The antiarrhythmic effect of intravenous nifekalant (NIF) was assessed in patients with VT/VF complicating acute coronary syndrome (ACS) according to our study protocol.</AbstractText>Among a series of 1,143 ACS patients, 41 patients who suffered sustained VT/VF were enrolled; 19 failed to respond to a preceding lidocaine (LID) injection. NIF was given first as an intravenous bolus injection (0.2 mg/kg) and then as a continuous intravenous infusion at a relatively low dose level (0.2 mg x kg(-1) x h(-1)). Sustained VT/VF was successfully inhibited by NIF in 34 patients (83%). In subgroup analysis, NIF achieved VT/VF inhibition in 79% of patients who received preceding LID and in 86% of patients who received direct NIF. There were no significant changes in systolic blood pressure or heart rate following NIF therapy. A corrected QT interval was significantly prolonged (P<0.01), whereas torsade de pointes developed in only 1 patient (2%).</AbstractText>An intravenous bolus injection and subsequent continuous infusion of NIF at a relatively low dosage were effective in treating severe ventricular tachyarrhythmias complicating ACS, reducing the potential risk of proarrhythmia.</AbstractText> |
6,324 | Current status of implantable cardioverter-defibrillator therapy in heart failure. | Sudden cardiac arrest is one of the leading causes of death in patients with heart failure (HF). The implantable cardioverter-defibrillator (ICD) is the only evidence-based treatment strategy for patients who have survived a life-threatening ventricular arrhythmic event. Randomized clinical trials have shown that specific subsets of HF patients with ischemic and nonischemic dilated cardiomyopathy benefit from ICD therapy for primary prevention of sudden cardiac arrest. Cardiac resynchronization therapy has become the device-based therapy of choice for improving symptoms and survival in severe HF patients with evidence of ventricular dyssynchrony. This review summarizes the current status of ICD therapy in treating HF patients based on randomized clinical trials and current practice guidelines. |
6,325 | [Ambulatory electrocardiographic recording (Holter) at the moment of a sudden death event]. | Arrhythmic sudden cardiac death due to electrical causes is an important clinical and public health problem, which is not yet solved. Ventricular fibrillation is the first cause of the event. It does not adjust to a single model, being a family with diverse electrocardiographic patterns that reveal different disorganization degrees. Many of these deaths happen without witness. We present a patient who was being studied after a first medical visit because of a previous syncope with spontaneous recovery, coursing with left bundle branch block. He was not receiving any antiarrhythmic drug and was asymptomatic at the time. He was wearing a long-term ambulatory electrocardiographic recorder (Holter), which became the sole witness of his death that occurred while he was alone at home. The recording revealed various malignant ventricular arrhythmia (torsades des pointes, ventricular flutter, ventricular fibrillation), immediately preceding events were an increased heart rate, extra-systoles, and left bundle branch block. This is the first recording of the whole sequence of malignant ventricular arrhythmias leading to death in a patient wearing a Hotter device obtained by our department, which has collected 750 Hotter ambulatory records per year for more than 20 years. The literature on the subject is reviewed. |
6,326 | Subarachnoid Hemorrhage Associated with Ventricular Fibrillation and Out-of-Hospital Cardiac Arrest. | Aneurysmal subarachonoid hemorrhage (SAH) is a common cause of out-of-hospital cardiac arrest (OHCA). Even after successful resuscitation, most of these SAH patients suffer brain death or enter a vegetative state. To our knowledge, survival without neurological damage from SAH following OHCA is quite a rare event. We treated a case of SAH who presented with OHCA and survived without neurological sequelae. A 50-year-old woman presented with ventricular fibrillation (VF), and was successfully resuscitated before hospital arrival. Since there was no evidence of acute coronary syndrome, a head CT scan was performed and established the diagnosis of SAH. On arrival, she was comatose, however, 3 hours after admission, her neurological status recovered. She underwent treatment for the ruptured aneurysms and was discharged from hospital without any neurological deficits. |
6,327 | Brugada syndrome case: difficult differentiation between a concealed form and tricyclic antidepressant-induced Brugada sign. | We describe a case of Brugada syndrome, in which recurrent syncope with convulsive seizures was induced after antidepressant treatment. The patient had been treated with five kinds of psychotropic drugs. The twelve-lead ECG after the syncope exhibited an RSR'-pattern in the precordial leads, however, a coved type ST-segment elevation was induced by a pilsicainide test. Although ventricular fibrillation was not induced in the electrophysiologic study, an ICD implantation was considered as the recommended therapy since Brugada syndrome unmasked by antidepressants could not be ruled out. The possible contribution of antidepressants to Brugada type ST-segment changes is discussed. |
6,328 | The antiarrhythmic effect and possible ionic mechanisms of pilocarpine on animal models. | This study was designed to evaluate the effects of pilocarpine and explore the underlying ionic mechanism, using both aconitine-induced rat and ouabain-induced guinea pig arrhythmia models. Confocal microscopy was used to measure intracellular free-calcium concentrations ([Ca(2+)](i)) in isolated myocytes. The current data showed that pilocarpine significantly delayed onset of arrhythmias, decreased the time course of ventricular tachycardia and fibrillation, reduced arrhythmia score, and increased the survival time of arrhythmic rats and guinea pigs. [Ca(2+)](i) overload induced by aconitine or ouabain was reduced in isolated myocytes pretreated with pilocarpine. Moreover, M(3)-muscarinic acetylcholine receptor (mAChR) antagonist 4-DAMP (4-diphenylacetoxy-N-methylpiperidine-methiodide) partially abolished the beneficial effects of pilocarpine. These data suggest that pilocarpine produced antiarrhythmic actions on arrhythmic rat and guinea pig models induced by aconitine or ouabain via stimulating the cardiac M(3)-mAChR. The mechanism may be related to the improvement of Ca(2+) handling. |
6,329 | A comparison of defibrillation efficacy between different impedance compensation techniques in high impedance porcine model. | Impedance compensation methods differ markedly among manufacturers and can play an important role in defibrillation success. In this study we compared the efficacy of two different commercial defibrillators based on defibrillation success in a high impedance porcine model of cardiac arrest. The first defibrillator (A) compensates high impedance by controlling current with fixed shock duration, while the second defibrillator (B) by prolonging the shock duration.</AbstractText>In 10 domestic male pigs weighing between 17 and 28 kg, ventricular fibrillation was electrically induced and untreated for 15s. Animals were randomized to receive defibrillations with either defibrillator A or defibrillator B, at maximum energy settings of which were 200 J for the defibrillator A and 360 J for the defibrillator B. A grouped up-down defibrillation threshold testing protocol was used to compare the success rate between the two defibrillators. A variable resistance, ranging from 80 to 200 ohm was placed in series with the defibrillation pads. After a recovery interval of 5 min, the sequence was repeated for a total of 60 test shocks for each animal.</AbstractText>The measured total pathway impedance was in a range of 108-278 ohm. The combined success rate was 49.5% for the two defibrillators in a total of 600 testing shocks. The success rate was significantly higher when the defibrillator A was employed in comparison with defibrillator B (63% vs. 36%, p=0.0001).</AbstractText>For transthoracic impedances greater than average, the current-based compensation technique was more effective than the duration-based compensation technique.</AbstractText> |
6,330 | Modern pacemakers: hope or hype? | In recent years, the role of implantable pacing devices has expanded beyond the arrhythmia horizon and contemporary pacemakers' attempt to meet the physiological needs of patients. Modern pacemakers' functions include various modes of dual-chamber pacing, rate-response algorithms with dual sensors for optimum physiological response, cardiac resynchronization therapy (CRT), arrhythmia-prevention algorithms, antitachycardia pacing, and hemodynamic monitoring. The automaticity features of pacemakers enable continuous or intermittent monitoring of various pacemaker parameters including battery voltage, pacing impedance, sensing levels, pacing thresholds, and daily activity log. Modern pacemakers offer "physiological pacing" algorithms that minimize ventricular pacing and reduce the incidence of atrial fibrillation significantly. Ventricular pacing in patients with intact atrioventricular (AV) conduction or intermittent advanced AV block should be minimized with a hope to reduce heart failure hospitalization and mortality. A reduction in all-cause mortality due to physiological pacing, except for the CRT, has yet to be demonstrated in a randomized trial. Overall, modern pacemakers have acceptable performances to fulfill the clinical needs and have a reasonable safety margin. Promising new technologies are currently under development and offer hope to patients who may one day derive both symptomatic and mortality benefit from these devices. |
6,331 | The association between T-wave morphology and life-threatening ventricular tachyarrhythmias in patients with congestive heart failure. | Whether T-wave morphology descriptors on the 12-lead electrocardiogram (ECG) can predict the occurrence of life-threatening ventricular arrhythmia in patients with advanced congestive heart failure is unclear.</AbstractText>Standard 12-lead ECGs were photoscanned and digitized for analysis in 27 heart failure patients with ventricular tachycardia/ventricular fibrillation (VT/VF; study group), as well as in 54 age- and sex-matched heart failure patients without life-threatening ventricular arrhythmia as a control group. Novel T-wave morphology descriptors were compared.</AbstractText>The results showed that the temporal descriptor, the lead dispersion (LD; 426.5 +/- 279.8 vs 189.0 +/- 125.7, P < 0.001), was significantly higher in the study than in the control group. The other T-wave morphology parameters, such as the T-wave morphology dispersion (45.7 +/- 20.1 vs 44.9 +/- 18.6), the total cosine between QRS and T wave (TCRT; -0.4 +/- 0.4 vs -0.5 +/- 0.3), and the normalized T-loop area (NTLA; 0.5 +/- 0.1 vs 0.4 +/- 0.1), were not significantly different between the two groups (all P value > 0.05). After an adjustment for other clinical variables, increased LD (odds ratio: 9.9, 95% confidence interval [CI]: 2.9-33.4, P < 0.001) or decreased NTLA (odds ratio: 0.4, 95% CI: 0.1-1.0, P =0.05) was associated with VT/VF.</AbstractText>The novel T-wave morphology analysis may help in identifying heart failure patients at high risk for VT/VF.</AbstractText> |
6,332 | Outpatient electrical cardioversion of atrial fibrillation: 8 years' experience. Analysis of shock-related arrhythmias. | Outpatient electrical cardioversion (EC) of atrial fibrillation is currently the standard of care. Shock-related arrhythmias may be particularly deleterious in this setting. Preoperative identification of high-risk patients may be very useful.</AbstractText>A retrospective analysis was made of 543 consecutive elective EC procedures in 457 outpatients over an 8-year period in a university cardiological institute. The protocol included adequate anticoagulation, intravenous anesthesia, direct current shock, and a direct observation after a shock to detect procedure-related complications. No patients were excluded due to severity of pathology or comorbidities. Clinical characteristics, energy delivered, medications, arrhythmic phenomena, and predictors of success and complications were analyzed.</AbstractText>Of 543 ECs performed, 88.2% restored sinus rhythm, which persisted at discharge in 83.2%. No anesthesia-related complications were detected. No thromboembolic complications were detected. Use of a biphasic cardioverter was the only predictor of success (P = 0.0001). The bradyarrhythmic complication rate was 1.5%. No ventricular arrhythmic events were detected. Atrial flutter was present in five of eight patients who developed complications versus 44 of 535 patients who had no complications (P < 0.0005), and prosthetic heart valves in four of eight complicated versus 40 of 535 uncomplicated cases (P = 0.0044). The combination of atrial flutter and prosthetic heart valve was found in four of eight complicated versus 11 of 535 uncomplicated cases (P < 0.0005).</AbstractText>Shock-related arrhythmias are essentially bradyarrhythmias. Atrial flutter and previous cardiac surgery identify a subgroup of patients at high risk of postshock bradyarrhythmic complications.</AbstractText> |
6,333 | Persistent atrial standstill and idioventricular rhythm in a patient with thalassemia intermedia. | We present a 57-year old male patient with thalassemia intermedia and right heart failure. He had a 30-year history of anemia and short-term iron therapy without blood transfusion. Hemoglobin level was 7.1 g/dl and hematocrit was 22.7%. White blood-cell and platelet counts, and serum ferritin level were normal. Electrocardiography showed irregular narrow QRS bradyarrhythmia, suggesting slow atrial fibrillation at a mean rate of 35 beats/min. Echocardiographic examination revealed dilatation of the right atrium and ventricle, depressed systolic right ventricular function, advanced tricuspid regurgitation, and mild pericardial effusion. In the electrophysiologic study, no electrical activity was recorded in the right atrium. It was inexcitable at multiple sites and no retrograde conduction to the right atrium could be elicited by ventricular pacing. His bundle (HB) recording showed fixed retrograde HB activation with ventricular rhythm originating from different foci. Retrograde V-H conduction time during ventricular rhythm was 95 msec and did not change. There was no retrograde nodal conduction. A VVIR pacemaker was implanted. During a six-month follow-up, he felt well, his functional capacity was NYHA class II, and his basic rhythm was widened QRS arrhythmia with a rate of 20 beats/min. To the best of our knowledge, atrial electrical inactivity together with right-heart failure and pericarditis confined to the right heart chambers has hitherto not been reported in thalassemic disorders. |
6,334 | Impact of type of atrial fibrillation and repeat catheter ablation on long-term freedom from atrial fibrillation: results from a multicenter study. | <AbstractText Label="BACKGROUND/OBJECTIVE" NlmCategory="OBJECTIVE">The purpose of this prospective multicenter study was to compare results of catheter ablation in patients with paroxysmal atrial fibrillation (PAF) and those with nonparoxysmal atrial fibrillation (NPAF). The impact and the role of repeat catheter ablation were assessed in patients with recurrence.</AbstractText><AbstractText Label="METHODS/RESULTS" NlmCategory="RESULTS">One thousand four hundred four patients underwent catheter ablation for atrial fibrillation (AF) performed by 12 operators at four institutions using a single technique guided by intracardiac echocardiography. Of these patients, 728 had PAF and 676 had NPAF. Among the NPAF patients, 293 had persistent AF and 383 had long-standing persistent AF. Patients with NPAF had a higher incidence of hypertension and/or structural heart disease (64.8% vs 48.5%, P = .003) and a lower mean left ventricular ejection fraction (53.3% +/- 8.7% vs 55.7 +/- 6.5%, P <.001). All patients underwent antral isolation of all four pulmonary veins and the superior vena cava. At mean follow-up of 57 +/- 17 months, 565 of 728 patients with PAF and 454 of 676 patients with NPAF (77.6% vs 67.2%, P <.001) had freedom from AF after a single ablation procedure. For arrhythmia recurrences, 74.2% (121/163) patients with PAF and 74.8% (166/222) with NPAF underwent repeat ablation, after which 92.4% patients with PAF and 84.0% patients with NPAF remained free from AF.</AbstractText>Pulmonary vein antrum isolation guided by intracardiac echocardiography results in significant freedom from AF, even when performed by multiple operators in different centers. At least moderate efficacy can be achieved in patients with NPAF, although the success rate is lower than in patients with PAF. Considerably higher success can be achieved in both groups with repeat ablation.</AbstractText> |
6,335 | Ventricular fibrillation in Rochester, Minnesota: experience over 18 years. | Survival following out-of-hospital cardiac arrest (OHCA) continues to be disappointingly low world-wide, despite advances in technology and international guidelines for resuscitation. Few cities or emergency medical service (EMS) agencies report patient outcomes after OHCA. Among those who do, survival from witnessed VF ranges from 7.7% to 39.9%, with only a few cities reporting rates higher than this. We report outcomes and incidence of VF OHCA over 18 years in a medium-sized city incorporating an aggressive approach to OHCA.</AbstractText>The city, which increased in population over the study period from 70,000 to 100,000 persons, utilizes an emergency response system which dispatches defibrillator-equipped police, fire-rescue and ambulance personnel simultaneously. Police and fire-rescue personnel are equipped with automated external defibrillators (AEDs). Advanced life-support is provided as needed by paramedics.</AbstractText>There were 454 arrests during the study period attributed to a cardiac cause. Of 271 bystander-witnessed arrests, 203 (74.9%) were in VF and 94 (46.3%) were discharged. Average time from 9-1-1 call to shock was relatively short: mean 6.5 min (S.D. 2.5 min). In a multivariable model, the interval from call to shock was strongly associated with neurologically intact survival (OR 0.72, 95% CI: 0.61-0.84 for each additional minute). The age- and sex-adjusted incidence of EMS-treated VF OHCA significantly (p<0.001) declined over the study period: 1991-1999: 37.9/100,000 (95% CI: 31.8-44.0), 2000-2008: 17.8/100,000 (95% CI: 14.4-21.2).</AbstractText>High survival from witnessed VF OHCA (46.3%) was achieved during the study period. Rapid response, and therefore rapid defibrillation, was the major contributor to survival.</AbstractText> |
6,336 | Atrioventricular (AV) node vagal stimulation by transvenous permanent lead implantation to modulate AV node function: safety and feasibility in humans. | Atrioventricular (AV) node vagal stimulation (AVNVS) has recently emerged as a novel approach to controlling AV dromotropic function. Animal studies have demonstrated that selective epicardial AVNVS is effective in controlling ventricular rate (VR) acutely and in the long term. Endocardial AVNVS has been shown to significantly reduce VR acutely during atrial fibrillation (AF) in humans. However, no data are available on its long-term reproducibility.</AbstractText>The purpose of this study was to demonstrate that the posteroseptal right atrium is a suitable site for permanent pacing and allows AVNVS in humans both acutely and during follow-up.</AbstractText>In 12 candidates for implantable cardioverter-defibrillator with a history of AF, the atrial lead was implanted in the posteroseptal right atrium, where advanced AV block was achieved during temporary high-frequency stimulation (HFS). On implantation and 3-month follow-up examination, HFS was delivered through the permanent lead to demonstrate the possibility to gradually slow the VR until complete AV block.</AbstractText>On implantation, VR during AF was gradually slowed until complete AV block, which was elicited at 4.3 V (0.2 ms, 50 Hz). After 3 months, this effect remained reproducible. No significant change in pacing thresholds was observed after 3 months. We observed one dislodgment and one microdislodgement of atrial leads.</AbstractText>Our study demonstrates, for the first time in humans, that selective placement of the atrial lead yields electrical characteristics suitable for permanent pacing and enables VR to be significantly reduced under HFS. These results, which were reproducible during follow-up, provide data for the development of device-based control of VR during AF.</AbstractText> |
6,337 | d,l-Sotalol reverses abbreviated atrial refractoriness and prevents promotion of atrial fibrillation in a canine model with left ventricular dysfunction induced by atrial tachypacing. | This study evaluated antiarrhythmic effects of d,l-sotalol in a canine atrial fibrillation (AF) model with left ventricular dysfunction.</AbstractText>Thirteen beagles (Sotalol group n=7 and Control group n=6) were subjected to atrial tachypacing (ATP) (400 beats/min) with intact atrioventricular conduction for 4 weeks. Oral d,l-sotalol (2 mg/kg) was administered 1 week after starting ATP and continued throughout the experiment. One week after starting ATP, atrial effective refractory periods (AERPs) were shortened in both groups. However, d,l-sotalol treatment gradually prolonged AERP, resulting in a significant prolongation of AERP compared with the Control group at 4 weeks (Control 76 +/-4 and Sotalol 126 +/-5 ms, p<0.01). d,l-Sotalol treatment showed lower AF inducibility and shorter AF duration at 4 weeks. In the control group, expressions of L-type Ca(2+) channel alpha1c and Kv4.3 mRNA were downregulated by 46.2% and 43.0%, respectively, after 4 weeks of ATP; d,l-sotalol treatment did not affect these changes.</AbstractText>d,l-Sotalol treatment prolonged AERP, even after atrial electrical remodeling had developed, and prevented AF perpetuation without affecting downregulated expression of L-type Ca(2+) channel alpha1c and Kv4.3 mRNA in an ATP-induced canine AF model.</AbstractText> |
6,338 | Elevated cardiac troponin I and relationship to persistence of electrocardiographic and echocardiographic abnormalities after aneurysmal subarachnoid hemorrhage. | Cardiac injury persistence after aneurysmal subarachnoid hemorrhage (aSAH) is not well described. We hypothesized that post-aSAH cardiac injury, detected by elevated cardiac troponin I (cTnI), is related to aSAH severity and associated with electrocardiographic and structural echocardiographic abnormalities that are persistent.</AbstractText>Prospective longitudinal study was conducted of patients with aSAH with Fisher grade >or=2 and/or Hunt/Hess grade >or=3. Serum cTnI was collected on Days 1 to 5; cohort dichotomized into peak cTnI >or=0.3 ng/mL (elevated) or cTnI <0.3 ng/mL. Relationships among cTnI and aSAH severity, 12-lead electrocardiography early (<or=4 days) and late (>or=7 days), Holter monitoring on Days 1 to 5, and transthoracic echocardiogram (left ventricular ejection fraction and regional wall motion abnormalities) early (Days 0 to 5) and late (Days 5 to 12) were evaluated.</AbstractText>Of 204 subjects, 31% had cTnI >or=0.3 ng/mL. cTnI >or=0.3 ng/mL was incrementally related to aSAH severity by admission symptoms (Hunt/Hess P=0.001) and blood load (Fisher P=0.028). More patients with cTnI >or=0.3 ng/mL had prolonged QTc on early (63% versus 30%, P<0.0001) and late electrocardiography (24% versus 7%, P=0.024). On Holter monitoring, more patients with cTnI >or=0.3 ng/mL had ventricular tachycardia/fibrillation (22% versus 9%, P=0.018) but not atrial fibrillation/flutter (P=0.241). Cardiac troponin I >or=0.3 ng/mL was associated with both early ejection fraction <50% (44% versus 5%, P<0.0001) and regional wall motion abnormalities (44% versus 4%, P<0.0001). Regional wall motion abnormalities predominated in basal and midventricular segments and persisted to some degree in 73% of patients affected, whereas ejection fraction <50% persisted in 59% of patients affected.</AbstractText>Cardiac injury is incrementally worse with increasing aSAH severity and associated with persistent QTc prolongation and ventricular arrhythmias. Regional wall motion abnormalities and depressed ejection fraction persist to some degree in the majority of those affected.</AbstractText> |
6,339 | A case with catecholaminergic polymorphic ventricular tachycardia unmasked after successful ablation of atrial tachycardias from pulmonary veins. | Catecholaminergic polymorphic ventricular tachycardia (VT) is characterized by polymorphic VT during exercise, and the association of atrial fibrillation (AF) has been reported. However, the mechanism of AF in this disease and the relationship between VT and AF has been obscured. We described a 13-year-old girl who referred for catheter ablation of exercise-induced paroxysmal AF. Multifocal atrial tachycardia mimicking AF on the surface electrocardiogram originated from multiple pulmonary veins (PVs). While AT became non-inducible after the isolation of four PVs, polymorphic VT was initiated by isoproterenol infusion. Polymorphic VT was suppressed during rapid atrial pacing. |
6,340 | Improved prognosis after using mild hypothermia to treat cardiorespiratory arrest due to a cardiac cause: comparison with a control group. | Patients who survive a cardiac arrest have a poor short-term prognosis in terms of mortality and neurological function. The use of mild hypothermia has been investigated in only a few randomized studies, but appears to be effective for treating these patients. The aim of this study was to investigate the effect of this treatment on survival and neurological outcomes.</AbstractText>We compared mild hypothermia and usual treatment in patients who had experienced a prolonged cardiac arrest due to ventricular fibrillation or tachycardia and who showed signs of neurological damage. Patient were divided into two groups: a control group of 28 patients and a group of 41 patients who were treated with hypothermia. Patients were assessed at discharge and at 6 months.</AbstractText>There was no significant difference between the two groups in baseline characteristics, including those of the cardiac arrest, or in the time to treatment. At discharge, neurological status was good in 18 patients (43.9%) in the hypothermia group but in only five (17.9%) in the control group (risk ratio=2.46; 95% confidence interval, 1.11-3.98; P=.029). At 6 months after discharge, neurological status was found to be good in 19 patients (46.3%) in the treatment group and six (21.4%) in the control group (risk ratio=2.16; 95% confidence interval, 1.05-3.36; P=.038). The effect of hypothermia may have been affected by various confounding factors.</AbstractText>Our findings demonstrate that hypothermic treatment after cardiac arrest prolonged by ventricular fibrillation or tachycardia helps improve the prognosis of anoxic encephalopathy.</AbstractText> |
6,341 | Risk of arrhythmias in myotonic dystrophy: trial design of the RAMYD study. | Myotonic dystrophy type 1 (DM1) is the most frequent muscular dystrophy in adults. DM1 is a multisystem disorder also affecting the heart with an increased incidence of sudden death, which has been explained with the common impairment of the conduction system often requiring pacemaker implantation; however, the occurrence of sudden death despite pacemaker implantation and the observation of major ventricular arrhythmias generated the hypothesis that ventricular arrhythmias may play a causal role as well. The aim of the study was to assess the 2-year cumulative incidence and the value of noninvasive and invasive findings as predictive factors for sudden death, resuscitated cardiac arrest, ventricular fibrillation, sustained ventricular tachycardia and severe sinus dysfunction or high-degree atrioventricular block.</AbstractText><AbstractText Label="METHODS/DESIGN" NlmCategory="METHODS">More than 500 DM1 patients will be evaluated at baseline with a clinical interview, 12-lead ECG, 24-h ECG and echocardiogram. Conventional and nonconventional indications to electrophysiological study, pacemaker, implantable cardioverter defibrillator or loop recorder implantation have been developed. In the case of an indication to electrophysiological study, pacemaker, implantable cardioverter defibrillator or loop recorder implant at baseline or at follow-up, the patient will be referred for the procedure. At the end of 2-year follow-up, all candidate prognostic factors will be tested for their association with the endpoints.</AbstractText>ClinicalTrials.gov ID NCT00127582.</AbstractText>The available evidence supports the hypothesis that both bradyarrhythmias and tachyarrhythmias may cause sudden death in DM1, but the course of cardiac disease in DM1 is still unclear. We expect that this large, prospective, multicenter study will provide evidence to improve diagnostic and therapeutic strategies in DM1.</AbstractText> |
6,342 | Characterization of a novel Nav1.5 channel mutation, A551T, associated with Brugada syndrome. | Brugada syndrome is a life-threatening, inherited arrhythmia disorder associated with autosomal dominant mutations in SCN5A, the gene encoding the human cardiac Na+ channel alpha subunit (Nav1.5). Here, we characterized the biophysical properties of a novel Brugada syndrome-associated Nav1.5 mutation, A551T, identified in a proband who was successfully resuscitated from an episode of ventricular fibrillation with sudden collapse. Whole-cell currents through wild-type (WT) Nav1.5 and mutant (A551T) channels were recorded and compared in the human embryonic kidney cell line HEK293T transfected with SCN5A cDNA and SCN1B cDNA, using the patch-clamp technique. Current density was decreased in the A551T mutant compared to the WT. In addition, the A551T mutation reduced Nav1.5 activity by promoting entry of the channel into fast inactivation from the closed state, thereby shifting the steady-state inactivation curve by -5 mV. Furthermore, when evaluated at -90 mV, the resting membrane potential, but not at the conventionally used -120 mV, both the percentage, and rate, of channel recovery from inactivation were reduced in the mutant. These results suggest that the DI-DII linker may be involved in the stability of inactivation gating process. This study supports the notion that a reduction in Nav1.5 channel function is involved in the pathogenesis of Brugada syndrome. The structural-functional study of the Nav1.5 channel advances our understanding of its pathophysiolgocial function. |
6,343 | [Rhythm and conductivity disorders in patients at the initial stages of metabolic syndrome]. | The aim of the work was to evaluate the prevalence of cardiac rhythm and conductance disturbances in patients with early manifestations of metabolic syndrome (MS). 24-hour ECG monitoring was undertaken in 105 patients meeting AHA/NHLBI (2005) MS criteria and in 79 healthy subjects. Exclusion criteria were the presence of diabetes mellitus, CHD, and obesity (body mass index > 40 kg/m2). MS was associated with an increased number of supraventicular extrasystoles (628.9 +/- 49.5 vs 415.9 +/- 57.9, p < 0.05) and ventricular extrasystoles (34.4 +/- 9.9 vs 11.8 +/- 6.5 for paired ones and 9.5 +/- 3.7 vs 2.2 +/- 4.0 for group ones, p < 0.05), higher frequency of tachyarrhythmia (supraventicular tachycardia: 18.1 vs 7.6%, p < 0.05; atrial fibrillation: 9.5 vs 2.5, p < 0.05; sinus node arrest: 6.7 vs 0%, p < 0.05). Regression analysis revealed significant correlation between arrhythmias and the number of components of the disease. It is concluded that cause-and-effect relationship between MS and cardiac rhythm disturbances is apparent at the early stage of the disease. |
6,344 | Intrapericardial delivery of amiodarone and sotalol: atrial transmural drug distribution and electrophysiological effects. | Amiodarone and sotalol are frequently used in the treatment of atrial fibrillation. However, oral and intravenous (IV) therapy with these drugs has suboptimal efficacy and is associated with serious extracardiac side effects. We hypothesized that intrapericardial (IPC) delivery produces antiarrhythmic effects at lower plasma drug concentrations than IV delivery. Goats (n = 27) were randomised into 5 groups receiving either IPC vehicle, amiodarone (IV or IPC) or dl-sotalol (IV or IPC). Epicardial and endocardial atrial effective refractory period and atrial response to burst pacing (rapid atrial response, RAR) were assessed before and after 3 hours of drug infusion at 2 mg.kg.h. IPC delivery produced steeply decreasing drug concentrations from epicardium to endocardium in both atria and ventricles. Plasma drug concentrations were significantly lower in IPC than in IV groups. IPC amiodarone and sotalol reduced epicardial RAR inducibility (-74% +/- 20% and -66% +/- 30%, respectively) compared with IV delivery (-11% +/- 17% and -17% +/- 28%, respectively; P < 0.05). Endocardial RAR inducibility was only reduced in the IPC amiodarone group (-70% +/- 17%, P < 0.05). In conclusion, IPC delivery of amiodarone and sotalol increases atrial drug concentration and antiarrhythmic effects at reduced plasma drug concentrations. These potential benefits are particularly prominent for IPC delivered amiodarone. |
6,345 | Idiopathic ventricular arrhythmia in a young man: a case report. | Ventricular ectopics can potentially lead to ventricular fibrillation (VF). A case of idiopathic VF that began as ventricular bigeminy is presented. A 30-year-old man lost consciousness transiently while driving but made a complete recovery soon after. He was pale and sweaty at the onset of the event. There was neither a history of ill health nor a family history of sudden cardiac death. He was asymptomatic on arrival at the emergency department (ED) with sinus tachycardia. Two hours later ventricular bigeminy was observed. This subtle presentation did not qualify him for being high risk according to the American College of Physician's recommendations or the San Francisco syncope rule, which almost led to his discharge from the ED. Despite this, he was admitted for observation. The patient had four VF arrests overnight, which were eventually terminated by emergency radiofrequency ablation. Upon further investigation, he was found to be normal on cardiac magnetic resonance imaging, echocardiogram and 24-h Holter monitoring. His serum biochemistry was normal, ruling out electrolyte disturbances. He eventually received an implantable cardioverter and remained free of recurrences in the subsequent months. This case serves as a reminder not to ignore ventricular ectopics or bigeminy. |
6,346 | Coronary vasospasm triggered ventricular fibrillation delayed after radiofrequency ablation of the right accessory pathway. | Ventricular fibrillation associated with coronary vasospasm developed 8 h after successful radiofrequency (RF) ablation of the right accessory pathway in an 81-year-old male. A segment of the coronary vasospasm was located close to the accessory pathway, where seven RF ablations had been applied. Although rare, physicians should carefully consider the risk of such events when an RF current is applied near a coronary artery. |
6,347 | Intracardiac QT variability in patients with structural heart disease on class III antiarrhythmic drugs. | We previously showed that increased intracardiac repolarization lability predicts life-threatening ventricular arrhythmias in patients with structural heart disease. Patients with structural heart disease frequently take antiarrhythmic drugs (AADs), which directly affect repolarization. The effect of AADs on the predictive value of repolarization lability is unknown. We hypothesized that increased intracardiac beat-to-beat QT variability predicts sustained ventricular tachyarrhythmias in structural heart disease patients on class III AADs. Intracardiac electrograms and surface electrocardiogram were simultaneously recorded at rest for 5 minutes in 500 patients (mean +/- SD age, 61 +/- 14 years; 368 male [74%]) with implanted implantable cardioverter-defibrillator for primary (295 patients, or 79%) or secondary prevention of sudden cardiac death. Mean (SD) follow-up currently reached 24.8 (11.7) months. Intracardiac QT variability index was an independent predictor of ventricular tachycardia/ventricular fibrillation events and fast ventricular arrhythmias with cycle length of 240 ms or less in the multivariate Cox model. Intracardiac QT variability was higher in patients on class III AADs than in those not taking these drugs. Increased intracardiac QT variability after adjustment for class III AADs use carried independent risk of life-threatening ventricular tachyarrhythmias. |
6,348 | Use of ECMO to temporize circulatory instability during severe Brugada electrical storm. | We describe the use of extracorporeal membrane oxygenation to temporize circulatory instability during almost incessant ventricular fibrillation in a patient with Brugada syndrome who had electively discontinued chronic amiodarone therapy. The extracorporeal membrane oxygenation was continued for 3 days after emergent delivery of the neonate, during which time the number of ventricular fibrillation episodes and internal defibrillations markedly decreased concomitant with administration of intravenous amiodarone and verapamil. Oral anti-arrhythmic therapy was subsequently reinstituted, and the remainder of the patient's hospital course was uneventful. |
6,349 | Long-term outcome of mitral valve repair for infective endocarditis. | In patients with mitral endocarditis, reconstruction of the damaged mitral valve (MV) is still challenging, and its durability remains unknown. We evaluated the long-term outcomes of MV repair for mitral regurgitation (MR) in patients with infective endocarditis.</AbstractText>From 1991 to 2006, 633 patients had MV repair for MR caused by leaflet prolapse: 78 had endocarditis (active in 14, healed in 64) and 555 had degenerative disease. Durability was assessed by reoperation and recurrent MR.</AbstractText>The overall hospital mortality rate was 1.0% (endocarditis 0% vs degenerative 1.1%; p = 0.99). The 10-year survival and freedom from reoperation were 91.1 +/- 1.6% and 92.2 +/- 1.7%, respectively, with no differences between endocarditis and degenerative disease. Older age, New York Heart Association class III or IV, impaired ventricular function, and no use of annuloplasty were independent predictors of all-cause death. Freedom from moderate or severe MR was 99.8 +/- 0.2% at 2 weeks, 91.9 +/- 1.5% at 5 years, and 83.3 +/- 2.3% at 10 years, for all patients and did not differ between groups at 10 years (p = 0.388). Anterior leaflet prolapse, preoperative atrial fibrillation, and no annuloplasty were independent predictors of recurrent MR. In endocarditis patients, recurrent MR was mainly caused by leaflet thickening and calcification, but not by recurrence of endocarditis.</AbstractText>MV repair for endocarditis is associated with low operative mortality and morbidity, and its long-term durability is comparable with that of repair for degenerative disease. This study suggests that a degenerative process causes late failure after MV repair for endocarditis.</AbstractText> |
6,350 | Prognosis among survivors of primary ventricular fibrillation in the percutaneous coronary intervention era. | Sudden cardiac death (SCD) constitutes one of the most prevalent modes of death and is mainly caused by primary ventricular fibrillation (VF), that is, VF in the acute setting of a first acute myocardial infarction (MI). Current guidelines for secondary prevention of SCD are based on data from the thrombolysis era. We analyzed follow-up data of a large group of primary VF survivors to determine prognosis and risk of SCD in patients who received contemporary MI treatment.</AbstractText>Patients in this study were included in the ongoing Dutch multicenter primary VF study between December 1999 and April 2007. Primary VF was defined as VF during the first ST-elevation myocardial infarction (STEMI). Patients surviving the first 30 days were analyzed in this study. Data on mortality, cause of death, hospitalization, and implantable cardioverter-defibrillator (ICD) implantation were retrieved from national databases. In addition, data on left ventricular ejection fraction and medication use during follow-up were retrieved.</AbstractText>In total, 341 primary VF patients (cases) and 292 STEMI patients without VF (controls) were included in the study. Demographic and infarct characteristics were comparable between both groups. The median follow-up was 3.33 years for cases and 3.69 for controls (P = .02). The left ventricular ejection fraction post-STEMI was 45.1% versus 46.5% (P = .342). During follow-up, 19 cases died versus 24 controls. Cox regression analysis showed no significant difference in survival between cases and controls (relative risk 0.59, 95% CI 0.15-2.30). Implantable cardioverter-defibrillators were implanted in 22 cases and 2 controls (P < .001), but only 2 cases and 1 control patient received appropriate ICD shocks. beta-Blocker use during follow-up was 84.4% in cases versus 76.2% in controls (P = .049). Of cases, 2.5% were rehospitalized for acute MI versus 10.1% of controls (P < .001). The numbers of admissions for acute coronary syndromes and chest pain were not different between groups.</AbstractText>In conclusion, patients who survive the first month after primary VF have a similar prognosis as patients with a STEMI without VF. This is the first study to address this question in the modern era of reperfusion therapy. Implantable cardioverter-defibrillator treatment in primary VF patients without residual ischemia or other risk factors can be safely withheld.</AbstractText> |
6,351 | Two-dimensional strain analysis in patients with hypertrophic cardiomyopathy and normal systolic function: a 12-month follow-up study. | Although left ventricular (LV) and left atrial (LA) echo indices may reliably reflect loading conditions in patients with hypertrophic cardiomyopathy (HCM), little is known about 2-dimensional strain imaging. We evaluated LV and LA 2-dimensional strain imaging in relation to long-term outcome in patients with HCM.</AbstractText>Fifty consecutive patients (58% men, aged 51 +/- 18 years) with familial HCM and normal LV ejection fraction underwent 2-dimensional LV and LA strain imaging; total LA strain was defined as the sum of maximum positive and maximum negative atrial strain. Patients were followed up for 12 months for cardiovascular events, defined as death or hospitalization for cardiovascular causes.</AbstractText>Twenty patients (40%) experienced an event after a median time of 98 days: 2 (4%) died and 18 (36%) were hospitalized. In multivariate analysis, total LA strain was the strongest predictor of 12-month outcome (odds ratio 0.858, 95% CI 0.771-0.954, P = .005); a cutoff of 21% predicted events with 90% sensitivity and 86% specificity. Total LA strain was also an independent predictor of atrial fibrillation requiring hospitalization (odds ratio 0.853, 95% CI 0.748-0.972, P = .017).</AbstractText>In patients with HCM and normal systolic function, total LA strain predicts 12-month outcome in terms of death and/or hospitalization.</AbstractText> |
6,352 | Local conduction block of the atria by premature stimulus in a patient with Brugada syndrome. | A 46-year-old man with type II Brugada electrocardiogram pattern changed to a type I Brugada type electrocardiogram pattern by class I antiarrhythmic drug (pilsicainide) underwent electrophysiologic study. Ventricular fibrillation was induced by double extrastimuli from the right ventricular (RV) apex. Monophasic action potentials (MAPs) were then recorded from the high right atrium. Duration of MAP at a coupling interval of 220 milliseconds was 122 milliseconds, and local activation of S2 spread to the left atrium. However, MAP at a coupling interval of 210 milliseconds was 112 milliseconds, and local activation of S2 failed to spread to the rest of atrium. |
6,353 | Development of a toolbox for electrocardiogram-based interpretation of atrial fibrillation. | Atrial fibrillation (AF) develops as a consequence of an underlying heart disease such as fibrosis, inflammation, hyperthyroidism, elevated intra-atrial pressures, and/or atrial dilatation. The arrhythmia is initiated by, or depends on, ectopic focal activity. Autonomic dysfunction may also play a role. However, in most patients, the actual cause of AF is difficult to establish, which hampers the selection of the optimal mode of treatment. This study aims to develop tools for assisting the physician's decision-making process.</AbstractText>Signal analytical methods have been developed for optimizing the assessment of the complexity of AF in all of the standard 12-lead signals. The development involved an evaluation of methods for reducing the signal components stemming from the electric activity of the ventricles (QRST suppression). The methods were tested on simulated recordings, on clinical recordings on patients in AF, and on patients exhibiting atrial flutter (AFL) and atrial tachycardia. The results have been published previously. Subsequently, the implementation of the algorithms in a commercially available electrocardiogram (ECG) recorder, an implementation referred to as its AF-Toolbox, has been carried out. The performance of this implementation was tested against those observed during the development stage. In addition, an improved visualization of the specific ECG components was implemented. This was enabled by providing a separate view on ventricular and atrial activity, which resulted from the steps implied in the QRST suppression. Furthermore, a search was initiated for identifying meaningful features in the cleaned up atrial signals.</AbstractText>When testing the implementation of the previously developed methods in the Toolbox on simulated and clinical data, the suppression of ventricular activity in the ECG produced residuals down to the level of physiologic background noise, in agreement with those reported on previously. The QRST suppression resulted in a better visualization of the atrial signals in AF, atrial AFL, sinus rhythm in the presence of atrioventricular blocks, or ectopic beats. Classifiers for AF and AFL that have been defined so far include the distinct spectral components (multiple basic frequencies), exhibiting distinct dominance in specific leads. The annotations of ventricular and atrial activities, ventricular and atrial trigger, as well as ratio between atrial and ventricular rates were greatly facilitated. The time diagram of ventricular and atrial triggers provides an additional view on rhythm disturbances.</AbstractText>The AF-Toolbox that is currently developed for clinical applications has the potential of reliably detecting and classifying AF, as well as to correctly describe atrioventricular conduction, propagation blocks and/or ectopic beats. Based on the results obtained, a first industrial prototype has been built, which will be used to assess its performance in a routine clinical environment. The availability of this tool will facilitate the search for meaningful signal features for identifying the source of AF in individual patients.</AbstractText> |
6,354 | New-onset atrial fibrillation as first clinical manifestation of latent Brugada syndrome: prevalence and clinical significance. | To evaluate the prevalence, clinical significance, and prognosis of latent Brugada syndrome (BrS) in patients with new-onset atrial fibrillation (AF) unmasked by class 1C antiarrhythmic drugs.</AbstractText>Between January 2000 and June 2008, all consecutive patients with new-onset AF, who after flecainide exhibited typical Brugada ECG pattern, underwent electrophysiologic, pharmacologic, and genetic testing. Among 346 patients [median age 53 years; interquartile range (IQR), 15], 11 (3.2%; median age 51 years; IQR, 19) diagnosed as lone AF exhibited typical Brugada ECG pattern. Genetic testing was negative. Ventricular tachycardia/ventricular fibrillation (VT/VF) was induced by electrophysiologic testing (five patients) or during flecainide infusion (one patient). Six patients with type 1 ECG pattern and inducible VT/VF underwent ICD implantation. During a median follow-up of 31.5 months (range: 10-85) after ICD implantation, three patients developed BrS and one of them experienced VF. Patients without ICD (five patients) remained asymptomatic during a median follow-up of 74 months. Persistent type 1 pattern occurred only in the three patients who developed BrS.</AbstractText>This study, for the first time, reveals the prevalence of latent BrS in patients with new-onset lone AF, which may precede VT/VF. Persistence of type 1 and ventricular tachyarrhythmias inducibility represents a marker of electrical instability leading to sudden death.</AbstractText> |
6,355 | Arrhythmias originating from the right ventricular outflow tract: how to distinguish "malignant" from "benign"? | Idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) in patients without structural heart diseases is generally considered as a benign ventricular arrhythmia (VA). However, "malignant" VA, ventricular fibrillation (VF), and/or polymorphic VT are occasionally initiated by VT or ventricular premature contraction (VPC) originating from the RVOT. In this review article, previous reports describing the malignant form of idiopathic RVOT VT are reviewed, and it is discussed how to distinguish the malignant form from the "benign" form of idiopathic VT originating from the RVOT. |
6,356 | Transient local injury current in right ventricular electrogram after implantable cardioverter-defibrillator shock predicts heart failure progression. | This study aimed to identify an early marker of functional impairment after an implantable cardioverter-defibrillator (ICD) shock as a predictor of heart failure progression.</AbstractText>The ICD population has substantial risk of death due to progressive pump failure.</AbstractText>Near-field (NF) bipolar right ventricular (RV) electrograms (EGMs) during induced ventricular fibrillation (VF) and 10 s after rescue ICD shock were analyzed in 310 patients (mean age 59 +/- 14.5 years, 219 men [71%]) with structural heart disease, New York Heart Association functional class I to III, and implanted with a single- or dual-chamber Medtronic (Minneapolis, Minnesota) ICD for primary (245 patients, 79%) or secondary prevention of sudden cardiac arrest. A local injury current (LIC) on NF RV EGM was defined as a deviation of EGM potential > or =1 mV or > or =15% of the preceding R-wave peak-to-peak amplitude.</AbstractText>During mean follow-up of 29.3 +/- 15.0 months, the combined end point of death or hospitalization due to congestive heart failure (CHF) exacerbation was documented in 40 patients (12.9%, or 5.3% per person-year of follow-up). LIC was observed in 106 patients. In multivariate risk analysis, after adjustment for baseline prognostic factors (ejection fraction, history of atrial fibrillation, diabetes mellitus) and appropriate ICD shocks during follow-up, patients with observed LIC after induced VF rescue ICD shock at ICD implantation were more likely to die or to be hospitalized (hazard ratio: 2.69; 95% confidence interval: 1.41 to 5.14; p = 0.003).</AbstractText>Transient LIC on bipolar NF RV EGM after induced VF rescue ICD shock is associated with increased risk of CHF progression, future hospitalizations due to CHF exacerbation, and subsequent heart failure death.</AbstractText>2009 by the American College of Cardiology Foundation</CopyrightInformation> |
6,357 | [Myocardial protection of cold autoblood cardioplegia in infants with congenital heart disease]. | To study the effects of cold autoblood cardioplegia on oxygen free radicals in the myocardium in infants who underwent cardiopulmonary bypass and to explore the possible mechanism of myocardial protection of autoblood cardioplegia.</AbstractText>Thirty infants with acyanotic congenital heat disease (CHD) (weight< or =8 kg) were randomized to receive cold crystalloid, cold blood or cold autoblood cardioplegia (n=10 each group) during cardiopulmonary bypass. The biopsy samples were taken from the right atrium just before heart arrest and after heart self-recovery for the measurement of malonaldehyde (MDA) and superoxide dismutase (SOD) contents. The time and the rate of the heart self-recovery to sinus rhythm, and the incidence of ventricular fibrillation were recorded during operation. The cardiac index (CI) and the dependence of positive inotropic drugs were monitored after operation.</AbstractText>Before the operation, there were no significant differences in myocardial MDA (0.87+/-0.14, 0.88+/-0.11 and 0.86+/-0.15 nmol/mg prot, respectively) and SOD contents (61.3+/-3.4, 69.2+/-3.1 and 64.4+/-4.2 U/g, respectively) among the crystalloid, the blood and the autoblood cardioplegia groups. After operation, the myocardial MDA content increased (3.12+/-0.21, 2.93+/-0.27 and 1.67+/-0.15 nmol/mg prot, respectively) and SOD content (42.6+/-2.3, 44.6+/-3.1 and 57.7+/-2.1 U/g, respectively) decreased significantly in the three groups (P<0.05 or 0.01). The autoblood cardioplegia group had lower myocardial MDA content and higher SOD content than the crystalloid and the blood cardioplegia groups (P<0.05). The time of heart self-recovery was shortened and the dependence of positive inotropic drugs were reduced in the autoblood cardioplegia group compared with the crystalloid and the blood cardioplegia groups (P<0.05). Post-operational CI in the autoblood cardioplegia group was significantly higher than that in the blood and the crystalloid cardioplegia groups. There were significant differences in the time of heart self-recovery, the dependence of positive inotropic drugs and the CI between the blood and the crystalloid cardioplegia groups (P<0.05 or 0.01).</AbstractText>Cold autoblood cardioplegia reduces oxygen free radicals in the myocardium, thus providing myocardial protections in infants undergoing cardiopulmonary bypass.</AbstractText> |
6,358 | [Antiarrhythmic effect of ethyl acetate extract from Chrysanthemum Morifolium Ramat on rats]. | To investigate the effect of ethyl acetate extract from Chrysanthemum Morifolium Ramat (CME) on experimental arrhythmia induced by ischemia/reperfusion or aconitine in rats and to explore its underlying mechanisms.</AbstractText>Arrhythmia model in intact rat was induced by aconitine (30 microg/kg body weight, i.v.). In isolated Langendorff perfused rat hearts, regional ischemia and reperfusion was induced by ligation and release of left anterior descending artery. The ventricular fibrillation threshold (VFT), effective refractory period (ERP), and diastolic excitation threshold (DET) in the isolated heart were measured. The action potentials of papillary muscle in rat right ventricle were recorded by conventional glass microelectrode technique.</AbstractText>Compared with control group CME significantly decreased the number and duration of ventricular tachycardia (VT); delayed the occurrence of ventricular premature beats (VPB) and VT induced by aconitine. Arrhythmia score of the CME group was lower than that in aconitine-treated group. CME markedly prolonged the ERP and increased the VFT in the isolated perfused rat hearts during ischemia and reperfusion. CME prolonged action potential duration at 50% and 90% repolarization of the right ventricular papillary muscles and decreased the maximal rate of rise of the action potential upstroke, but did not affect the resting potential, amplitude of action potential.</AbstractText>CME can reduce myocardial vulnerability and exerts its antiarrhythmic effects induced by aconitine or ischemia/reperfusion, which may be related to its prolongation of action potential duration and effective refractory period that enhance the electrophysiological stability of myocardiaium.</AbstractText> |
6,359 | Non-invasive assessment of left ventricular relaxation during atrial fibrillation using mitral flow propagation velocity. | To elucidate the usefulness of the early diastolic mitral flow propagation velocity (V(p)) obtained from colour M-mode Doppler for non-invasively assessing left-ventricular (LV) relaxation during atrial fibrillation (AF).</AbstractText>Ten healthy adult dogs were studied to correlate V(p) with the invasive minimum value of the first derivative of LV pressure decay (dP/dt(min)) and the time constant of isovolumic LV pressure decay (tau) at baseline, during rapid and slow AF, and during AF after inducing myocardial infarction. There were significant positive and negative curvilinear relationships between V(p) and dP/dt(min) and tau, respectively, during rapid AF. After slowing the ventricular rate, the average value of V(p) increased, while dP/dt(min) increased and tau decreased. After inducing myocardial infarction, the average value of V(p) decreased, while dP/dt(min) decreased and tau increased.</AbstractText>The non-invasively obtained V(p) evaluates LV relaxation even during AF regardless of ventricular rhythm or the presence of pathological changes.</AbstractText> |
6,360 | Reconstructing and registering three-dimensional rotational angiogram of left atrium during ablation of atrial fibrillation. | Three-dimensional (3D) image of left atrium (LA) can greatly facilitate ablation of atrial fibrillation (AF). Reconstructing method using computed tomography (CT) has certain limitations. The 3D image of LA can be intraprocedurally reconstructed by a rotational angiography technique.</AbstractText>Forty-six patients undergoing AF ablation were included in this study. Preprocedural CT imaging and intraprocedural reconstructing 3D rotational angiogram (3DRA) of LA were performed in all the patients. Rapid ventricular pacing (RVP, 300 ms) was used to inhibit the drainage of atrium. During RVP, contrast medium was injected into the LA, and rotational angiography was performed. The 3DRA was reconstructed and was registered with the live fluoroscopy. The 3DRA was evaluated in comparison to the CT image. In the navigation of the registered 3DRA, the ablation of AF was performed.</AbstractText>Forty-four 3DRAs (95.7%) were successfully reconstructed and registered with the live fluoroscopy. The LA anatomy was delineated in the 3DRA in comparison to a CT image. AF ablation was successfully performed in the 44 patients in the navigation of the registered 3DRA. There were good correlations in the PV ostial diameter and the LA volume as assessed by 3DRA in comparison to a CT image (r>=0.87). The radiation exposure in rotational angiography was substantially less than that in CT scanning (2.7+/-0.9 mSv vs. 24.9+/-3.1 mSv, P<0.001).</AbstractText>It is feasible to reconstruct and register the 3DRA with live fluoroscopy using the RVP method during the ablation of AF.</AbstractText> |
6,361 | Duality of conduction in an atriofascicular pathway during antidromic tachycardia. | Cycle length alternation in atrioventricular reentrant tachycardia due to alternating conduction time over the dual atrioventricular (AV) nodal pathways has been well described. Atriofascicular pathways with decremental conduction characteristics (Mahaim fibers) are known to contain accessory AV nodal tissue. We describe a case of cycle-length alternans in antidromic tachycardia through an atriofascicular pathway because of alternation in conduction time in the antegrade limb. The possible mechanisms of this phenomenon, rarely described in atriofascicular pathways, are discussed. |
6,362 | The use of vasopressin for treating vasodilatory shock and cardiopulmonary arrest. | To discuss 3 potential mechanisms for loss of peripheral vasomotor tone during vasodilatory shock; review vasopressin physiology; review the available animal experimental and human clinical studies of vasopressin in vasodilatory shock and cardiopulmonary arrest; and make recommendations based on review of the data for the use of vasopressin in vasodilatory shock and cardiopulmonary arrest.</AbstractText>Human clinical studies, veterinary experimental studies, forum proceedings, book chapters, and American Heart Association guidelines. HUMAN AND VETERINARY DATA SYNTHESIS: Septic shock is the most common form of vasodilatory shock. The exogenous administration of vasopressin in animal models of fluid-resuscitated septic and hemorrhagic shock significantly increases mean arterial pressure and improves survival. The effect of vasopressin on return to spontaneous circulation, initial cardiac rhythm, and survival compared with epinephrine is mixed. Improved survival in human patients with ventricular fibrillation, pulseless ventricular tachycardia, and nonspecific cardiopulmonary arrest has been observed in 4 small studies of vasopressin versus epinephrine. Three large studies, though, did not find a significant difference between vasopressin and epinephrine in patients with cardiopulmonary arrest regardless of initial cardiac rhythm. No veterinary clinical trials have been performed using vasopressin in cardiopulmonary arrest.</AbstractText>Vasopressin (0.01-0.04 U/min, IV) should be considered in small animal veterinary patients with vasodilatory shock that is unresponsive to fluid resuscitation and catecholamine (dobutamine, dopamine, and norepinephrine) administration. Vasopressin (0.2-0.8 U/kg, IV once) administration during cardiopulmonary resuscitation in small animal veterinary patients with pulseless electrical activity or ventricular asystole may be beneficial for myocardial and cerebral blood flow.</AbstractText> |
6,363 | Successful biphasic transthoracic defibrillation of a dog with prolonged, refractory ventricular fibrillation. | To describe a case of spontaneous ventricular fibrillation in a dog in which biphasic defibrillation was life saving.</AbstractText>Ventricular fibrillation occurred in a 7-year-old female Australian Heeler during recovery from anesthesia following pacemaker implantation. Resuscitative efforts including immediate delivery of transthoracic monophasic defibrillation shocks of escalating energy and administration of vasopressors were unsuccessful. However, a single biphasic shock restored sinus rhythm despite prolonged duration of the arrhythmia.</AbstractText>This case suggests greater efficacy of biphasic defibrillation compared with traditional monophasic defibrillation. In this dog the newer, biphasic technology was life saving after monophasic shocks failed repeatedly to terminate ventricular fibrillation.</AbstractText> |
6,364 | Dronedarone: a new antiarrhythmic agent for the treatment of atrial fibrillation. | In the armamentarium for rhythm control, amiodarone has been a mainstay of therapy for the management of atrial fibrillation (AF). Although amiodarone has shown to be effective in maintaining sinus rhythm, it has many extracardiac adverse effects. Dronedarone, a benzofuran amiodarone derivative, is structurally modified to reduce toxicities often associated with chronic amiodarone therapy. With the addition of a methylsulfonyl group, dronedarone is less lipophilic, has lower tissue accumulation, and a much shorter serum half-life of 24 hours compared with amiodarone. Dronedarone is also designed without the iodine moieties that are responsible for thyroid dysfunctions associated with amiodarone. Similar to amiodarone, dronedarone exhibits electrophysiologic characteristics of all 4 Vaughan Williams classifications. Phase III clinical trials have shown dronedarone to be effective at reducing ventricular rate, reducing recurrence of AF, and reducing cardiovascular morbidity and mortality in patients with AF or atrial flutter (AFL). However, dronedarone was associated with increased mortality in one study that included patients with severe heart failure (HL) and left ventricular dysfunction. Overall, dronedarone appears to be well tolerated. The most common side effects are gastrointestinal in nature and include nausea, vomiting, and diarrhea. Because of its more favorable adverse effect profile, dronedarone is likely to be a useful addition to the therapeutic management of AF. However, further comparative studies with amiodarone are needed to define dronedarone's place in therapy more clearly. |
6,365 | Survival analysis in patients with preserved left ventricular function and standard indications for permanent cardiac pacing randomized to right ventricular apical or septal outflow tract pacing. | Optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. A prospective randomized trial was done to compare long-term effect of permanent RV apex (RVA) vs RV outflow tract (RVOT) pacing on the all-cause and cardiovascular mortality.</AbstractText>A total of 122 consecutive patients (70 men, 69 +/-11 years), with standard pacing indications were randomized to RVA (66 patients) or RVOT (56 patients) ventricular lead placement. After the 10-year follow-up period the mortality data were summarized on the basis of an intention-to-treat analysis. During the long-term follow-up, 31 patients from the RVA group died vs 24 patients in the RVOT group (hazard ratio (HR), 0.96; 95% confidence interval (CI), 0.57-1.65; P=0.89). There were 10 cardiovascular deaths in the RVA and 12 in the RVOT group (HR, 1.04; 95%CI, 0.45-2.41; P=0.93). There were no differences in the all-cause or cardiovascular mortality between the pacing sites after adjustment for age, gender, arterial hypertension, atrial fibrillation, New York Heart Association class and left ventricular end-diastolic diameter.</AbstractText>The RVOT provides no additional benefit in terms of long-term survival over RVA pacing.</AbstractText> |
6,366 | Exercise-induced ventricular arrhythmias and risk of sudden cardiac death in patients with hypertrophic cardiomyopathy. | Non-sustained ventricular tachycardia (NSVT) during ambulatory electrocardiographic monitoring (typically occurring at rest or during sleep) is associated with an increased risk of sudden cardiac death in patients with hypertrophic cardiomyopathy. The prevalence and prognostic significance of ventricular arrhythmias during exercise is unknown.</AbstractText>This was a cohort study, with prospective data collection. We studied 1380 patients, referred to a cardiomyopathy clinic in London, UK [mean age 42 years (SD 15); 62% male; mean follow-up 54 (SD 49) months]. Patients underwent two-dimensional and Doppler echocardiography, upright exercise testing, and Holter monitoring. Twenty-seven patients [mean age 40 (SD 14) years (18-64); 22 (81.5%) male] had NSVT (24) or ventricular fibrillation (VF) (3) during exercise. During exercise, 13 (54.2%) had more than one run of NSVT (maximum 5) with a mean heart rate of 221 (SD 48) b.p.m. Patients with exercise NSVT/VF had more severe hypertrophy (22.6 vs. 19.5 mm, P = 0.009) and larger left atria (47.3 vs. 43.7 mm, P = 0.03). Male gender was significantly associated with exercise NSVT/VF [22 (81.5%) vs. 832 (61.5%), P = 0.03]. Eight (29.6%) of the exercise NSVT/VF patients died or had a cardiac event (SD/ICD discharge/transplant) compared with 150 (11.1%) patients without exercise NSVT/VF, P = 0.008. Patients with NSVT/VF had a 3.73-fold increase in risk of SD/ICD discharge (HR 95% CI: 1.61-8.63, P = 0.002). Exercise NSVT alone was associated with a 2.82-fold increased risk (HR 95% CI: 1.02-7.75, P = 0.049). In multivariable analysis with other risk markers, exercise NSVT/VF (but not NSVT alone) was independently associated with an increased risk of SD/ICD [HR 3.14 (95% CI: 1.29-7.61, P = 0.01)].</AbstractText>Ventricular arrhythmia during symptom limited exercise is rare in patients with hypertrophic cardiomyopathy, but is associated with an increased risk of sudden cardiac death.</AbstractText> |
6,367 | Anticoagulation in patients with heart failure. | The decision to anti-coagulate patients with heart failure (HF) is a difficult one, with limited data available to support clinical judgment. Thromboembolic complications, both arterial (stroke) and venous (deep vein thrombosis and pulmonary embolism), remain a significant cause of mortality and morbidity in this population. The pathophysiology of thrombogenesis in HF may be contextualized in the classic triad of stasis, endothelial dysfunction and hypercoagulability. Dilated cardiac chambers, reduced systolic function, and left ventricular aneurysm or thrombus have been suggested as potential contributing factors. HF is associated with activation of inflammatory and neuroendocrine pathways, leading to endothelial dysfunction and a prothrombotic state with dysregulated platelets and activation of the coagulation cascade. The epidemiology of thromboembolic events in HF is poorly defined. Most studies are retrospective and include patients with concurrent atrial fibrillation. The current body of health outcomes research is reviewed to identify the specific etiological factors, prevalence, and impact of thromboembolic events in this patient population. Conflicting analyses exist regarding the risks and benefits of prophylaxis in HF. The data surrounding several classes of therapeutic agents are synthesized. Recent clinical trials on anticoagulation and HF are reviewed, including WATCH, WASH, and WARCEF. The absence of compelling clinical trial data leaves many unanswered questions regarding systemic anticoagulation in patients with HF. |
6,368 | Dronedarone. | Amiodarone is the most effective antiarrhythmic drug for maintaining sinus rhythm for patients with atrial fibrillation. Extra-cardiac side effects have been a limiting factor, especially during chronic use, and may offset its benefits. Dronedarone is a noniodinated benzofuran derivative of amiodarone that has been developed for the treatment of atrial fibrillation and atrial flutter. Similar to amiodarone, dronedarone is a potent blocker of multiple ion currents, including the rapidly activating delayed-rectifier potassium current, the slowly activating delayed-rectifier potassium current, the inward rectifier potassium current, the acetylcholine activated potassium current, peak sodium current, and L-type calcium current, and exhibits antiadrenergic effects. It has been studied for maintenance of sinus rhythm and control of ventricular response during episodes of atrial fibrillation. Dronedarone reduces mortality and morbidity in patients with high-risk atrial fibrillation, but may be unsafe in those with severe heart failure. This article will review evidence of safety and effectiveness of dronedarone in patients with atrial fibrillation. |
6,369 | Anesthetic management of apicoaortic bypass in patients with severe aortic stenosis. | Apicoaortic bypass (AAB), or apicoaortic conduit insertion, is a conventional surgical method that has been regaining attention due to the aging population and the increasing number of repeat surgeries. The indication for the procedure has been extended as an alternative for aortic stenosis when the usual sternotomy or aortic clamping is considered to be difficult, e.g., in patients with severe calcification of the ascending aorta (porcelain aorta), or in patients with a patent coronary artery bypass graft located adjacent to the posterior surface of the sternum. Herein, we report our recent anesthetic management of three patients undergoing AAB. Once the apicoaortic conduit is inserted, blood from the left ventricle is ejected via two routes, the narrowed native aortic valve and the apicoaortic conduit. Thus, it is necessary to elucidate any change in blood flow after the withdrawal of the extracorporeal circulation, by using intraoperative transesophageal echocardiography. Furthermore, if a rigid apical connector is not used, anastomosis of the cardiac apex and conduit is conducted under ventricular fibrillation without the infusion of cardioplegic solution; thus, patients are deemed likely to suffer increased myocardial damage. As a rigid apical connector was not used in the three present patients, the administraction of adequate catecholamines was needed for the withdrawal of the extracorporeal circulation. In addition, because those undergoing AAB often have extremely poor cardiac reserve preoperatively owing to the administration of adequate catecholamines was needed for the withdrawal of the extracorporeal circulation. In the three present patients, anesthetic management was successful, and there were no intraoperative or immediate postoperative complications. |
6,370 | Cardiac autonomic neural remodeling and susceptibility to sudden cardiac death: effect of endurance exercise training. | Sudden cardiac death resulting from ventricular tachyarrhythmias remains the leading cause of death in industrially developed countries, accounting for between 300,000 and 500,000 deaths each year in the United States. Yet, despite the enormity of this problem, both the identification of factors contributing to ventricular fibrillation as well as the development of safe and effective antiarrhythmic agents remain elusive. Subnormal cardiac parasympathetic regulation coupled with an elevated cardiac sympathetic activation may allow for the formation of malignant ventricular arrhythmias. In particular, myocardial infarction can reduce cardiac parasympathetic regulation and alter beta-adrenoceptor subtype expression enhancing beta(2)-adrenoceptor sensitivity that can lead to intracellular calcium dysregulation and arrhythmias. As such, myocardial infarction can induce a remodeling of cardiac autonomic regulation that may be required to maintain cardiac pump function. If alterations in cardiac autonomic regulation play an important role in the genesis of life-threatening arrhythmias, then one would predict that interventions designed to either augment parasympathetic activity and/or reduce cardiac adrenergic activity would also protect against ventricular fibrillation. Recently, studies using a canine model of sudden death demonstrate that endurance exercise training (treadmill running) enhanced cardiac parasympathetic regulation (increased heart rate variability), restored a more normal beta-adrenoceptor balance (i.e., reduced beta(2)-adrenoceptor sensitivity and expression), and protected against ventricular fibrillation induced by acute myocardial ischemia. Thus exercise training may reverse the autonomic neural remodeling induced by myocardial infarction and thereby enhance the electrical stability of the heart in individuals shown to be at an increased risk for sudden cardiac death. |
6,371 | T-wave inversion: cardiac memory or myocardial ischemia? | This article presents a case report of a 74-year-old man with T-wave inversion (TwI) in atrial fibrillation noted during routine pacemaker interrogation. The patient was seen for routine pacemaker interrogation, at which time he was noted to have underlying atrial fibrillation. A12-lead electrocardiogram of the atrial fibrillation revealed significant TwIs. He was subsequently worked up for myocardial ischemia and was found to have a moderate-sized,moderate-degree inferior wall myocardial perfusion defect. He was subsequently referred for a cardiac catheterization. The cardiac catheterization revealed nonobstructive coronary artery disease. The follow-up electrocardiogram revealed persistent but attenuated TwI.The TwIs were attributed to cardiac memory, a common but infrequently recognized phenomenon of which many clinical practitioners are unaware. Cardiac memory is due to the T wave tracking the preceding abnormal QRS complex and can be induced by right ventricular pacing or arrhythmias. |
6,372 | A comparison of 2 types of chest compressions in a porcine model of cardiac arrest. | Chest compressions performed by some medical workers are of poor quality, which are too few and shallow with incomplete release. This study was designed to compare the effects of these clinical quality chest compressions with standard manual chest compressions in a porcine model of cardiac arrest.</AbstractText>Ventricular fibrillation was induced in 18 pigs by programed electrical stimulation. Then, 40 mg methylene blue was injected into right atrium after 4 minutes of untreated ventricular fibrillation (VF), followed by cardiopulmonary resuscitation for 9 minutes. Defibrillation was attempted at 13 minutes of cardiac arrest. Animals of no restoration of spontaneous circulation after 4 times of defibrillations were announced dead and dissected immediately to observe the cerebral perfusion with methylene blue coloration. Resuscitated animals were executed to remove the tissues of pallium, cardiac muscle, kidney, and liver for histopathology after evaluating a porcine Cerebral Performance Category score at 24 hours after cardiac arrest. All animals were randomized to the following 2 groups: (1) standard manual chest compressions group (n = 9)-chest compression rates were kept at 100 +/- 5 cpm and compression depth at 50 +/- 1 mm with complete release by Heartstart MRx Monitor; (2) clinical quality chest compressions group (n = 9)-chest compression rates were kept at 80 +/- 5 cpm and compression depth at 37 +/- 1 mm with incomplete release.</AbstractText>Compared with clinical quality chest compressions, standard manual chest compressions produced greater restoration of spontaneous circulation, neurologically normal 24-hour survival, and histopathologic findings.</AbstractText>High-quality chest compressions improve outcomes of resuscitation, especially postresuscitation brain damage.</AbstractText> |
6,373 | Persistent ventricular fibrillation during therapeutic hypothermia and prolonged high-dose vasopressor therapy: case report. | Recent emphasis on high quality prehospital cardiopulmonary resuscitation has resulted in more out-of-hospital cardiac arrest victims surviving to the emergency department. As such, standardized in-hospital post-cardiac arrest care is necessary to assure optimal neurological recovery. Although therapeutic hypothermia has arisen as a key component in the post-cardiac arrest care paradigm, its interaction with other therapies remains poorly defined.</AbstractText>The purpose of this communication is to demonstrate a potential interaction between therapeutic hypothermia and routinely administered resuscitation medications.</AbstractText>We present a case of idiopathic ventricular fibrillation in a previously healthy 36-year-old man who developed persistent ventricular fibrillation in the setting of mild therapeutic hypothermia and high doses of routine resuscitation medications.</AbstractText>This case illustrates the importance of understanding the potential interaction between therapeutic hypothermia and resuscitation medications along with the need for a systematic and standardized, multi-disciplinary approach to post-cardiac arrest care.</AbstractText>Copyright © 2012 Elsevier Inc. All rights reserved.</CopyrightInformation> |
6,374 | Potential danger of ocular compression in paroxysmal supraventricular tachycardia in patients with latent preexcitation. | The vagal maneuver is the first line of therapeutic available for patients with paroxysmal supraventricular tachycardia. It increases vagal tone and includes the traditional ocular compression, carotid sinus massage, and Valsalva maneuver. A 40-year-old man was admitted because of 180 beats/min regular narrow QRS-complex tachycardia. The physician in the emergency department had performed an ocular compression, and at its ending, the tachycardia degenerated into unstable hemodynamically high ventricular rate atrial fibrillation. It was reverted to sinus rhythm by electrical shock. The electrophysiologic study documented a latent posterolateral bypass tract, with an anterograde refractory period of 210 milliseconds, which was successfully ablated. |
6,375 | Origin of complex behaviour of spatially discordant alternans in a transgenic rabbit model of type 2 long QT syndrome. | Enhanced dispersion of repolarization has been proposed as an important mechanism in long QT related arrhythmias. Dispersion can be dynamic and can be augmented with the occurrence of spatially out-of-phase action potential duration (APD) alternans (discordant alternans; DA). We investigated the role of tissue heterogeneity in generating DA using a novel transgenic rabbit model of type 2 long QT syndrome (LQT2). Littermate control (LMC) and LQT2 rabbit hearts (n = 5 for each) were retrogradely perfused and action potentials were mapped from the epicardial surface using di-4-ANEPPS and a high speed CMOS camera. Spatial dispersion (Delta APD and Delta slope of APD restitution) were both increased in LQT2 compared to LMC (Delta APD: 34 +/- 7 ms vs. 23 +/- 6 ms; Delta slope: 1.14 +/- 0.23 vs. 0.59 +/- 0.19). Onset of DA under a ramp stimulation protocol was seen at longer pacing cycle length (CL) in LQT2 compared to LMC hearts (206 +/- 24 ms vs. 156 +/- 5 ms). Nodal lines between regions with APD alternans out of phase from each other were correlated with conduction velocity (CV) alternation in LMC but not in LQT2 hearts. In LQT2 hearts, larger APD dispersion was associated with onset of DA at longer pacing CL. At shorter CLs, closer to ventricular fibrillation induction (VF), nodal lines in LQT2 (n = 2 out of 5) showed persistent complex beat-to-beat changes in nodal line formation of DA associated with competing contribution from CV restitution and tissue spatial heterogeneity, increasing vulnerability to conduction block. In conclusion, tissue heterogeneity plays a significant role in providing substrate for ventricular arrhythmia in LQT2 rabbits by facilitating DA onset and contributing to unstable nodal lines prone to reentry formation. |
6,376 | Modification of cardiovascular ion channels by gene therapy. | Delivery of genes to the heart and vasculature for therapeutic purposes is an exciting strategy that is approaching clinical reality. Abnormalities of expression or function of ion channels is central to many cardiovascular diseases and gene delivery to modify ion channels is an appealing alternative to traditional therapy with small-molecule drugs. Potential therapeutic targets include hypertrophy and heart failure, atrioventricular node modification in atrial fibrillation, ventricular tachycardia and hypertension. Numerous approaches for gene delivery are under development, including use of tissue-specific promoters in viral vectors. For other applications, such as development of biological pacemakers, cells can be transduced with pacemaker genes in vitro, and then the cells implanted within the heart. There are short-term hurdles to therapeutic gene delivery to modify cardiovascular ion channels, but in the intermediate and longer term, the outlook is promising. |
6,377 | [Differences between hospitals in prognosis after resuscitated out-of-hospital cardiac arrest patients]. | There are substantial differences in long-term survival of patients resuscitated from out-of-hospital cardiac arrest, and the level of care during hospitalization may be a contributing factor. The purpose of this study was to determine if a difference in long-term prognosis between hospitals could be detected in patients surviving cardiac arrest in Copenhagen.</AbstractText>The mobile emergency care unit attempted resuscitation in 1,098 patients with out-of-hospital cardiac arrest in the period 2002 to 2006, among whom return of spontaneous circulation occurred in 336 (30%) of the patients admitted to hospital. Survival was determined using the Central Population Registry through Statistics Denmark.</AbstractText>Patients admitted to a tertiary facility were younger, more frequently male, they had more commonly ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT) as their initial rhythm, and they had more frequently received bystander cardiopulmonary resuscitation. Survival at 4.6 years was 41% in patients admitted to the tertiary hospital and 10% in patients admitted to other hospitals, p < 0.0001. After adjustment for other known risk factors, patients admitted to other hospitals had a hazard ratio of 1.8 for death (95% confidence interval: 1,4-2,5) compared with patients admitted to a tertiary facility.</AbstractText>The survival rate after out-of-hospital cardiac arrest was significantly higher in patients admitted to a tertiary facility than among patients admitted to less specialized hospitals. Further studies are needed to identify causal factors.</AbstractText> |
6,378 | [Hypertension and the heart]. | Within the latest ten years research in left ventricular hypertrophy as cardiac target organ damage has uncovered its prognostic importance, and studies indicate that treatment with angiotensin II receptor blockade is most effective in reducing left ventricular hypertrophy. In addition, reduction of left ventricular mass is associated with substantial and significant reduction of cardiovascular morbidity and mortality. Hypertension is strongly associated with increased risk of subsequent heart failure. Meta analysis data suggests that reduction in blood pressure is also associated with very substantial reductions in incident heart failure. In addition, the authors suggest that atrial fibrillation should be considered target organ damage with the resulting implications in terms of blood pressure reduction in guidelines, and that modern treatment of atrial fibrillation should also include reduction of traditional cardiovascular risk factors as well as blood pressure reduction for blood pressures exceeding 130/185 mmHg. Reductions which should be achieved using angiotensin converting enzyme inhibitor or angiotensin receptor blockers in order to improve the hemodynamic status of the patient. |
6,379 | [Aortic valve replacement through right thoracotomy; report of a case]. | A 78-year-old female was admitted to our hospital with a diagnosis of severe aortic valve regurgitation. She had had dyspnea on effort and syncope twice in 5 months. She had also suffered from right pneumonia 8 years before, and her respiratory function was severely constrictive. Chest X-ray showed her mediastinum significantly shifted toward the right side. Chest computed tomography (CT) revealed the main pulmonary artery, right atrium (RA) and right pulmonary veins also shifted toward the right. We planned right thoracotomy at 4th intercostals space to obtain a good surgical field. A cardiopulmonary bypass was established by RA appendage drainage and femoral artery perfusion. Aortic valve replacement(AVR) was performed successfully after aortic clamp. Though defibrillator pads were placed on her back and the anterior wall of the left chest during operation, no ventricular fibrillation occurred. AVR via right thoracotomy is considered to be a good option for such a mediastinum shifted case. |
6,380 | Dronedarone: a promising alternative for the management of atrial fibrillation. | Atrial fibrillation (AF) is the most frequently encountered chronic arrhythmia associated with significant morbidity. It is generally encountered in the elderly, and will presumably become more prevalent in the future due to the increasing proportion of the elderly in the population. Major studies on AF have demonstrated no significant difference between rhythm and rate control in terms of mortality. However, young population with new-onset or lone AF, or patients in whom the maintenance of sinus rhythm is a must (due to recurrent thromboembolic events etc.) still gives rise to significant concerns related to the obligatory long-term prophylaxis. The long-term administration of the currently available conventional agents (amiodarone, dofetilide, sotalol, propafenone,flecainide etc.) is considered as a 'double edged sword' due to the presence of life-threatening adverse effects including pro-arrhythmia and organ toxicity associated with these agents. Several molecules are being developed for the management of AF. However, only a few novel agents confer promising results with respect to safety and efficacy issues in the major studies.</AbstractText>Dronedarone is an amiodarone analogue without iodine moiety in its structure, and is similar to amiodarone with regard to its structural and electrophysiological properties. Dronedarone is largely denuded of the potentially life-threatening adverse effects of anti-arrhythmics. Major clinical studies have demonstrated both rhythm and rate-controlling efficacy of dronedarone compared to placebo without any serious adverse effects in patients with AF. However, the ANDROMEDA trial, a large scale study including patients hospitalized for symptomatic congestive heart failure (with severely depressed left ventricular systolic functions) was prematurely terminated due to the increased mortality in the dronedarone arm compared to placebo indicating a lack of safety in this group of patients. Conversely, the recently published ATHENA study (including more than 4,600 high risk patients, but excluding those with severe heart failure) demonstrated a significant reduction in cardiovascular hospitalizations and cardiovascular mortality with dronedarone compared to placebo. In contrast, the DIONYSOS study, comparing dronedarone with amiodarone, demonstrated better safety, but lower efficacy of dronedarone for the maintenance of sinus rhythm in patients with AF.</AbstractText>Further clinical trials (including head to head comparison with other conventional anti-arrhythmics) are still required to determine the place of dronedarone in the management of AF. The present review focuses on basic and clinical aspects of dronedarone, a novel agent for the management of AF.</AbstractText> |
6,381 | Lack of gelsolin promotes perpetuation of atrial fibrillation in the mouse heart. | Gelsolin (gsn) is involved in the reorganization of the cytoskeleton, thereby modulating cardiomyocytal L-type Ca(2+) channels. We investigated global cardiac electrophysiological characteristics in a gsn-deficient (gsn(-/-)) mouse strain.</AbstractText>Using transvenous catheterization, atrial and ventricular stimulation were performed in 15 male mice [eight gsn(-/-), seven wild-type (gsn(+/+))]. Surface ECG, standard electrophysiological parameters, and inducibility of atrial fibrillation (AF) were evaluated.</AbstractText>The surface ECG showed shorter PQ (37.8 +/- 4.6 versus 42.9 +/- 2.7 ms; P = 0.02), but longer QRS (16.5 +/- 1.8 versus 13.9 +/- 1.2 ms; P = 0.005) and QT intervals (38.5 +/- 2.2 versus 35.6 +/- 2.4 ms, P = 0.03) in gsn(-/-). Gsn(-/-) exhibited significantly higher susceptibility to induction of prolonged AF episodes > or =60 s [six of eight gsn(-/-) versus one of seven gsn(+/+); P = 0.04]. Sustained AF episodes > or =10 min were observed in 50% of the gsn-deficient animals.</AbstractText>Gsn deficiency results in perpetuation of inducible episodes of atrial fibrillation. Altered L-type Ca(2+) currents and disturbed Ca(2+) handling known to be associated to gsn deficiency likely contribute to this effect.</AbstractText> |
6,382 | Current concepts and management strategies in atrial flutter. | After atrial fibrillation, atrial flutter (AFL) is the most important and most common atrial tachyarrhythmia. Atrial flutter describes an electrocardiographic model of atrial tachycardia >or=240/min, with a uniform and regular continuous wave-form. There is classically a 2:1 conduction across the atrioventricular (AV) node; as a result, the ventricular rate is usually one-half the flutter rate in the absence of AV node dysfunction. AFL can be harmful by impairing the cardiac output and by encouraging atrial thrombus formation that can lead to systemic embolization. There are four major concerns that must be addressed in the treatment of AFL: reversion to normal sinus rhythm (NSR); maintenance of NSR; control of the ventricular rate; and prevention of systemic embolization. Our review will highlight strategies for reverting patients back to NSR and then maintaining them in NSR, with emphasis on the recent updates, including the role of ablation in the management of atrial flutter. |
6,383 | Bayesian classification of clinical practice guidelines. | Clinical practice guidelines are generally constructed from an admixture of expert consensus opinion, case-control studies, and randomized controlled trials (RCTs) and are categorized according to the methodological quality of the underlying data (level of evidence) and the trade-off between the benefits and risks of treatment (class of recommendation). The process is driven principally by conventional statistical significance and does not specifically consider the clinical importance of the alternative treatment effects. We herein propose a more formal quantitative algorithm for the construction of guidelines using Bayes's theorem to integrate the clinical trial evidence with a range of prior belief representing the skeptical point of view embodied in the null hypothesis (to the effect that treatment can be expected to produce no reduction in risk), and the enthusiastic point of view embodied in the alternative hypothesis (to the effect that treatment can be expected to produce a specified clinically important reduction in risk). The operative practical utility of this algorithm is illustrated by application to a representative meta-analysis of RCTs. We conclude that this quantitative schema has the potential to improve the quality and cost of evidence-based clinical management. |
6,384 | The relationship between high-frequency right ventricular pacing and paroxysmal atrial fibrillation burden. | Right ventricular pacing increases the risk of persistent atrial fibrillation (AF) in the long term. The effects of right ventricular pacing on paroxysmal AF (PAF) are unknown. The aim was to examine the effect of right ventricular pacing on AF burden (AFB) in patients with symptomatic drug-resistant PAF. Pooled analysis of pacemaker-derived counters and AF diagnostic data from the Atrial Fibrillation Therapy (AFT) and Pacemaker Atrial Fibrillation Suppression (PAFS) randomized anti-AF pacemaker algorithm trials were used.</AbstractText>Five hundred and fifty-four patients from the AFT (n = 372) and PAFS (n = 182) were studied. The individual percentages of pacing, Atrial Sense Ventricular Pace (ASVP), Atrial Pace Ventricular Pace (APVP), and Atrial Pace Ventricular Sense (APVS) as well as total ventricular pacing during synchronous rhythm (VPinSR, %) were examined for an effect on AFB. Three hundred and twenty-one (AFT, age 64 +/- 11, 55% male) and 79 (PAFS, age 71 +/- 8, 54% male) patients had complete data for analysis. Increased VPinSR was weakly associated with an increased AFB (effect size-10% VPinSR increased AFB by only 0.03%) in AFT (P = 0.04) but not PAFS (P = 0.98) or the pooled analysis (P = 0.95). None of the synchronous paced modalities (ASVP, APVP, APVS) significantly increased AFB compared with sinus rhythm (Atrial Sense Ventricular Sense) (P = ns).</AbstractText>No pacing modality, atrial or ventricular, had a significant effect on AFB. On the basis of these data, the detrimental effect of high-frequency right ventricular pacing on AFB in paced PAF patients, unlike with persistent AF, appears to be minimal in the short term.</AbstractText> |
6,385 | Association of MMP-9 gene polymorphisms with atrial fibrillation in hypertensive heart disease patients. | MMP-9 plays an important role in the pathogenesis of arrhythmogenic atrial remodeling, and may contribute to the development and persistence of atrial fibrillation (AF). Functional polymorphisms in the MMP-9 gene which lead to altered MMP-9 production and/or activity may modulate an individual's susceptibility to AF.</AbstractText>A total of 881 hypertensive heart disease patients of Chinese Han population (128 with and 753 without AF) were recruited in this study. The MMP-9 -1562C>T and R279Q genotypes were determined using PCR-RFLP method. The plasma concentration of MMP-9 was measured by ELISA.</AbstractText>Both the genotype distributions and allele frequencies of the -1562C>T polymorphism were significantly different between the AF and control group (P=0.007 and P=0.002, respectively). The T allele carriers (TT + CT) had significantly increased risk of AF compared with the CC homozygotes (OR 1.94, 95% CI 1.20-3.14; adjusted P=0.006) in a logistic regression model after controlling age, left atrial dimension, and the use of angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers. The T allele carriers also had increased plasma MMP-9 levels compared with CC homozygotes in both AF patients and control subjects. No relationship between R279Q polymorphism and AF was found in this cohort.</AbstractText>The -1562C>T polymorphism of MMP-9 gene is significantly associated with AF risk in Chinese Han patients with hypertensive heart disease. The -1562T allele which is associated with increased expression of MMP-9 might be a genetic risk for the development of AF in this cohort.</AbstractText> |
6,386 | Incidence of atrial fibrillation during very long-term follow-up after radiofrequency ablation of typical atrial flutter. | Radiofrequency ablation is an effective treatment for typical atrial flutter (AFL) but long-term results may be hampered by atrial fibrillation (AF).</AbstractText>To determine the incidence and predictors of AF during very long-term follow-up after radiofrequency ablation of typical AFL.</AbstractText>From November 1998 to December 2000, patients who underwent successful radiofrequency ablation for cavotricuspid isthmus-dependent AFL in our centre were followed prospectively.</AbstractText>Of the 135 patients followed (mean age: 62+/-11 years), 69 (51%) had structural heart disease. Mean left ventricular ejection fraction was 52+/-11%. Patients were analysed according to preablation AF history: group 1 included patients with AFL (N=71); group 2 included patients with AFL and AF (N=64). During a median [interquartile range] follow-up of 7.8 [7.0-8.4] years, new-onset or recurrent AF was experienced by 99 (73%) patients: 44 (62%) in group 1 and 55 (86%) in group 2. Although most episodes occurred in the first 2 years postablation, AF prevalence increased continuously over time. Preablation AF history predicted AF occurrence (hazard ratio: 2.10, 95% confidence interval: 1.40-3.14; p=0.001), as did left atrial diameter (hazard ratio: 1.05 per 1 mm increase; 95% confidence interval: 1.02-1.08; p<0.001). AF evolved to become permanent in 24% of group 1 and 47% of group 2 patients (p=0.005).</AbstractText>During long-term follow-up, most patients will experience AF after ablation of typical AFL. Preablation AF history and left atrial enlargement predict postablation AF occurrence.</AbstractText> |
6,387 | Who survives cardiac arrest in the intensive care units? | The aim of this study was to evaluate the factors related to outcome regarding in-intensive care unit (ICU) cardiac arrest (IICA) in a university hospital.</AbstractText>Adult nontraumatic ICU patients who sustained IICA were prospectively enrolled. Several patient and event-related variables, as well as outcomes, were recorded and summarized based on the revised Utstein-style template.</AbstractText>A total of 202 episodes of IICA happened during the study period. Return of spontaneous circulation (ROSC) was achieved in 127 patients (62.9%), whereas the overall survival-to-discharge rate was 15.3% (31 patients). In univariate analysis, a shorter duration of resuscitation and pulseless ventricular tachycardia/ventricular fibrillation (VT/VF) as initial arrest rhythm represented better outcomes. Independent predictors of survival to hospital discharge were VT/VF as the initial rhythm (odds ratio [OR], 3.81; 95% confidence interval [CI], 1.50-9.67; P = .005), lower Acute Physiology and Chronic Health Evaluation II score (OR 0.92, 95% CI 0.87-0.98, P = .008), and shorter resuscitation durations (OR 0.91, 95% CI 0.87-0.96, P < .001).</AbstractText>Shorter resuscitation duration and initial VT/VF are predictors for both ROSC and hospital survival, whereas lower Acute Physiology and Chronic Health Evaluation II scores predict the latter.</AbstractText> |
6,388 | [Treatment of atrial fibrillation in heart failure]. | Treatment of patients with both atrial fibrillation and heart failure remains uneasy. In theory maintenance of sinus rhythm is desirable but the only pharmacological intervention able to do it safely is amiodarone. A trial of strategy randomisation, restoration of sinus rhythm or slowing of atrial fibrillation, has been done in patients with both atrial fibrillation and heart failure. This trial, named AF-CHF has shown neutral results, the 2 strategies, rhythm control or simple rate control were similar in terms of mortality. Dronedarone is an innovative drug bringing new possibilities in the treatment of atrial fibrillation but it is contra-indicated in case of severe heart failure. Another possible approach is that of non pharmacological techniques. Sinus rhythm maintenance may be obtained by pulmonary vein isolation. The other possibility is the ablation of atrio-ventricular node with implantation of a pacemaker, technique which is reserved to selected patients. |
6,389 | Left ventricular non-compaction: clinical features and cardiovascular magnetic resonance imaging. | It is apparent that despite lack of family history, patients with the morphological characteristics of left ventricular non-compaction develop arrhythmias, thrombo-embolism and left ventricular dysfunction.</AbstractText>Forty two patients, aged 48.7 +/- 2.3 yrs (mean +/- SEM) underwent cardiovascular magnetic resonance (CMR) for the quantification of left ventricular volumes and extent of non-compacted (NC) myocardium. The latter was quantified using planimetry on the two-chamber long axis LV view (NC area). The patients included those referred specifically for CMR to investigate suspected cardiomyopathy, and as such is represents a selected group of patients.</AbstractText>At presentation, 50% had dyspnoea, 19% chest pain, 14% palpitations and 5% stroke. Pulmonary embolism had occurred in 7% and brachial artery embolism in 2%. The ECG was abnormal in 81% and atrial fibrillation occurred in 29%. Transthoracic echocardiograms showed features of NC in only 10%. On CMR, patients who presented with dyspnoea had greater left ventricular volumes (both p < 0.0001) and a lower left ventricular ejection fraction (LVEF) (p < 0.0001) than age-matched, healthy controls. In patients without dyspnoea (n = 21), NC area correlated positively with end-diastolic volume (r = 0.52, p = 0.0184) and end-systolic volume (r = 0.56, p = 0.0095), and negatively with EF (r = -0.72, p = 0.0001).</AbstractText>Left ventricular non-compaction is associated with dysrrhythmias, thromboembolic events, chest pain and LV dysfunction. The inverse correlation between NC area and EF suggests that NC contributes to left ventricular dysfunction.</AbstractText> |
6,390 | Methods for calculating coronary perfusion pressure during CPR. | Coronary perfusion pressure (CPP) is a major indicator of the effectiveness of cardiopulmonary resuscitation in human and animal research studies, however, methods for calculating CPP differ among research groups. Here we compare the 6 published methods for calculating CPP using the same data set of aortic (Ao) and right atrial (RA) blood pressures. CPP was computed using each of the 6 calculation methods in an anesthetized pig model, instrumented with catheters with Cobe pressure transducers. Aortic and right atrial pressures were recorded continuously during electrically induced ventricular fibrillation and standard AHA CPR. CPP calculated from the same raw data set by the 6 calculation methods ranged from -1 (signifying retrograde blood flow) to 26 mmHg (mean +/- SD of 15 +/- 11 mmHg). The CPP achieved by standard closed chest CPR is typically reported as 10-20 mmHg. Within a single study the CPP values may be comparable; however, the CPP values for different studies may not be a reliable indicator of the efficacy of a given CPR method. Electronically derived true mean coronary perfusion pressure is arguably the gold standard method for representing coronary perfusion pressure. |
6,391 | Predictive value of cardiac autonomic indexes and MIBG washout in ICD recipients with mild to moderate heart failure. | We aimed at evaluating the combined use of heart rate variability (HRV), baroreflex sensitivity (BRS), and MIBG imaging in the risk stratification for sudden cardiac death (SCD) of patients with mild to moderate heart failure.</AbstractText>Twenty-five patients (17 male and 8 female, mean age 63 +/- 5 years, mean LVEF 36 +/- 3%) with a recently implanted defibrillator (ICD) and mild (NYHA I-II) heart failure due to either ischemic (n = 15) or dilated (n = 10) cardiomyopathy were studied. One week after ICD implantation they underwent (a) baroreflex sensitivity (BRS) evaluation to bolus phenylephrine by the Oxford method, (b) 24-h heart rate variability (HRV) assessment, and (c) MIBG imaging. The mean patient follow-up was 32 +/- 10 months. Simple correlation and stepwise multiple regression analysis was performed to evaluate (a) if the number of sustained ventricular tachycardia (cycle length <330 ms) or fibrillation episodes per month is related to one or more of MIBG, BRS, and HRV indexes and (b) if MIBG % washout is related to HRV and/or BRS.</AbstractText>The frequency of fast ventricular arrhythmic episodes (FVAE) demonstrated an inverse relation to BRS (p < 0.0001), rMSSD (p = 0.001), and pNN50 (p = 0.0034), while it was positively related to LF (p < 0.0001) and MIBG % washout (p = 0.001). BRS, LF, rMSSD, and MIBG washout were also independent predictors of FVAE. MIBG washout was related to only one HRV marker (SDNN-I, p < 0.0001), while no correlation was observed with BRS.</AbstractText>In ICD recipients with well-compensated heart failure, autonomic markers derived from BRS, HRV, and MIBG studies are related to FVAE. These markers have limited inter-dependency and constitute useful means for SCD risk stratification in this subgroup of patients.</AbstractText> |
6,392 | Effect of hypothermia therapy after outpatient cardiac arrest due to ventricular fibrillation. | Several investigators have emphasized the positive effect of hypothermia therapy on patients who have suffered from cardiac arrest. Salvaging patients from circulatory collapse is a pivotal task, but it is unclear whether additional hypothermia can practically contribute to an improvement in the neurological outcome.</AbstractText>Since December 2005, our hospital has been using hypothermia therapy. Forty-six comatose patients after recovery of spontaneous circulation were consecutively enrolled in the present study. Twenty-five of the enrolled patients received hypothermia therapy and 21 did not because they were treated prior to 2005. The time from collapse to spontaneous circulation (P=0.09), the rates of performance of bystander CPR (P=0.370) and presence of a witnessed collapse (P=0.067) were not significantly different between the recovery group (n=28) and the non-recovery group (n=18). The additional hypothermia therapy was an independent predictor of neurological recovery (P=0.005, OR 6.5, 95%CI 1.74-24.27). The recovery rate was significantly higher in patients who received hypothermia therapy (80%) compared to those who did not (38%).</AbstractText>Hypothermia therapy is very useful for treating patients who have had an out-of-hospital cardiac arrest; it should be induced rapidly and smoothly.</AbstractText> |
6,393 | Structural determinants for histamine H(1) affinity, hERG affinity and QTc prolongation in a series of terfenadine analogs. | In the late 1980's reports linking the non-sedating antihistamines terfenadine and astemizole with torsades de pointes, a form of ventricular tachyarrhythmia that can degenerate into ventricular fibrillation and sudden death, appeared in the clinical literature. A substantial body of evidence demonstrates that the arrhythmogenic effect of these cardiotoxic antihistamines, as well as a number of structurally related compounds, results from prolongation of the QT interval due to suppression of specific delayed rectifier ventricular K+ currents via blockade of the hERG-IKr channel. In order to better understand the structural requirements for hERG and H(1) binding for terfenadine, a series of analogs of terfenadine has been prepared and studied in both in vitro and in vivo hERG and H(1) assays. |
6,394 | Passive oxygen insufflation is superior to bag-valve-mask ventilation for witnessed ventricular fibrillation out-of-hospital cardiac arrest. | Assisted ventilation may adversely affect out-of-hospital cardiac arrest outcomes. Passive ventilation offers an alternate method of oxygen delivery for these patients. We compare the adjusted neurologically intact survival of out-of-hospital cardiac arrest patients receiving initial passive ventilation with those receiving initial bag-valve-mask ventilation.</AbstractText>The authors performed a retrospective analysis of statewide out-of-hospital cardiac arrests between January 1, 2005, and September 28, 2008. The analysis included consecutive adult out-of-hospital cardiac arrest patients receiving resuscitation with minimally interrupted cardiopulmonary resuscitation (CPR) consisting of uninterrupted preshock and postshock chest compressions, initial noninvasive airway maneuvers, and early epinephrine. Paramedics selected the method of initial noninvasive ventilation, consisting of either passive ventilation (oropharyngeal airway insertion and high-flow oxygen by nonrebreather facemask, without assisted ventilation) or bag-valve-mask ventilation (by paramedics at 8 breaths/min). The authors determined adjusted neurologically intact survival from hospital and public records and by telephone interview and mail questionnaire. The authors compared adjusted neurologically intact survival between ventilation techniques by using generalized estimating equations.</AbstractText>Among the 1,019 adult out-of-hospital cardiac arrest patients in the analysis, 459 received passive ventilation and 560 received bag-valve-mask ventilation. Adjusted neurologically intact survival after witnessed ventricular fibrillation/ventricular tachycardia out-of-hospital cardiac arrest was higher for passive ventilation (39/102; 38.2%) than bag-valve-mask ventilation (31/120; 25.8%) (adjusted odds ratio [OR] 2.5; 95% confidence interval [CI] 1.3 to 4.6). Survival between passive ventilation and bag-valve-mask ventilation was similar after unwitnessed ventricular fibrillation/ventricular tachycardia (7.3% versus 13.8%; adjusted OR 0.5; 95% CI 0.2 to 1.6) and nonshockable rhythms (1.3% versus 3.7%; adjusted OR 0.3; 95% CI 0.1 to 1.0).</AbstractText>Among adult, witnessed, ventricular fibrillation/ventricular tachycardia, out-of-hospital cardiac arrest resuscitated with minimally interrupted cardiac resuscitation, adjusted neurologically intact survival to hospital discharge was higher for individuals receiving initial passive ventilation than those receiving initial bag-valve-mask ventilation.</AbstractText> |
6,395 | Efficacy of antiarrhythmic drugs in arrhythmogenic right ventricular cardiomyopathy: a report from the North American ARVC Registry. | This study sought to examine the efficacy of empiric antiarrhythmic drugs in a rigorously characterized cohort of arrhythmogenic right ventricular cardiomyopathy (ARVC) patients.</AbstractText>Antiarrhythmic drugs are important in protecting against ventricular arrhythmias in ARVC, but no studies have provided data in a group rigorously screened for the disease.</AbstractText>Antiarrhythmic medicines were examined in all subjects with implantable cardioverter-defibrillators (ICDs) enrolled in the North American ARVC Registry. A Cox proportional hazards model was used to account for time on each drug, and a hierarchical analysis was performed for repeated measures within individuals.</AbstractText>Ninety-five patients were studied, with a mean follow-up of 480 +/- 389 days. Fifty-eight (61%) received beta-blockers, and these medicines were not associated with an increased or decreased risk of ventricular arrhythmias. Sotalol was associated with a greater risk of any clinically relevant ventricular arrhythmia as defined by sustained ventricular tachycardia or ICD therapy (hazard ratio [HR]: 2.55, 95% confidence interval [CI]: 1.02 to 6.39, p = 0.045), but this was not statistically significant after adjusting for potential confounders. An increased risk of any ICD shock and first clinically relevant ventricular arrhythmia while on sotalol remained significant after multivariable adjustment. Those on amiodarone (n = 10) had a significantly lower risk of any clinically relevant ventricular arrhythmia (HR: 0.25, 95% CI: 0.07 to 0.95, p = 0.041), a finding that remained significant after multivariable adjustment.</AbstractText>In a cohort of well-characterized ARVC subjects, neither beta-blockers nor sotalol seemed to be protective. Evidence from a small number of patients suggests that amiodarone has superior efficacy in preventing ventricular arrhythmias.</AbstractText> |
6,396 | Relation of N-terminal pro-B-type natriuretic peptide to symptoms, severity, and left ventricular remodeling in patients with organic mitral regurgitation. | Natriuretic peptides reflect cardiac stress and may therefore be useful in the management of patients with valvular heart disease. Data regarding these biomarkers in organic mitral regurgitation (MR) are sparse. In this study, 144 patients with moderate or severe organic MR were prospectively enrolled in an observational, multicenter study to analyze the relation of N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) to symptoms, severity of MR, and echocardiographic parameters. NT-pro-BNP levels (median 373 pg/ml, interquartile range 150 to 997) were associated with age, gender, creatinine, New York Heart Association (NYHA) functional class, atrial fibrillation, left ventricular (LV) end-systolic dimension, and the LV ejection fraction. Independent predictors of increased NT-pro-BNP levels were NYHA functional class (p = 0.003), atrial fibrillation (p = 0.005) and LV end-systolic dimension (p = 0.029). MR severity and left atrial dimension were not independently associated with NT-pro-BNP levels. NT-pro-BNP levels increased significantly with NYHA class (p <0.001) but not with MR severity (p = 0.144). NT-pro-BNP levels were significantly higher in symptomatic patients than in asymptomatic patients (582 pg/ml [interquartile range 246-1,360] vs 157 pg/ml [interquartile range 64 to 256], p <0.0001). The area under the receiver-operating characteristic curve to predict symptoms for NT-pro-BNP was 0.80 (95% confidence interval 0.71 to 0.88), which was significantly higher than for all echocardiographic variables (p <0.001 for all). In conclusion, NYHA functional class, atrial fibrillation, and LV end-systolic dimension are independent predictors of increased NT-pro-BNP levels in patients with moderate or severe organic MR. Therefore, NT-pro-BNP may be helpful in the clinical evaluation and management of patients with MR, especially when it is doubtful whether symptoms are related to MR or not. |
6,397 | Relation between myocardial infarct size and ventricular tachyarrhythmia among patients with preserved left ventricular ejection fraction following fibrinolytic therapy for ST-segment elevation myocardial infarction. | In the era of early reperfusion therapy for ST-segment elevation myocardial infarction, preserved left ventricular (LV) function is common. Despite preservation of LV ejection fraction (LVEF), there remains a spectrum of risk for adverse cardiovascular events, including ventricular tachycardia (VT) and ventricular fibrillation (VF). Larger infarct size has been independently associated with death, VT/VF, and heart failure in the post-myocardial infarction population. It was hypothesized that infarct size, as estimated by peak serum creatine kinase (CK)-MB concentration, would be associated with the incidence of VT/VF in patients with preserved LV function after ST-segment elevation myocardial infarctions. The Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis In Myocardial Infarction 28 (CLARITY-TIMI 28) study enrolled 3,491 patients with ST-segment elevation myocardial infarctions who underwent fibrinolytic therapy. The association between estimated infarct size (ratio of peak CK-MB to the upper limit of normal), the LVEF (measured using left ventriculography or echocardiography), and the incidence of VT/VF through 30 days was assessed. A total of 1,436 patients underwent assessments of LV function, of whom 1,133 had adequate CK-MB for analysis. The median LVEF in this group was 55% (interquartile range 45% to 65%), and most patients (n = 814 [87.1%]) had LVEF > or =40%. Among patients with LVEF > or =40%, the ratio of peak CK-MB to the upper limit of normal was significantly associated with the incidence of VT/VF through 30 days (2.2%, 3.7%, and 5.5% across tertiles, respectively, p = 0.041 for trend) and the incidence of the composite of cardiovascular death, heart failure, shock, and VT/VF through 30 days (3.7%, 6.0%, 8.5%, respectively, p = 0.018 for trend). In conclusion, in patients with ST-segment elevation myocardial infarction with preserved LV function after reperfusion therapy, larger infarct size, as estimated by peak serum CK-MB concentration, is significantly associated with VT/VF as well as other adverse clinical outcomes. |
6,398 | Direct His bundle pacing post AVN ablation. | Atrioventricular nodal (AVN) ablation with concomitant pacemaker implantation is one of the strategies that reduce symptoms in patients with atrial fibrillation (AF). However, the long-term adverse effects of right ventricular (RV) apical pacing have led to the search for alternating sites of pacing. Biventricular pacing produces a significant improvement in functional capacity over RV pacing in patients undergoing AVN ablation. Another alternative site for pacing is direct His bundle to reduce the adverse outcome of RV pacing. Here, we present a case of direct His bundle pacing using steerable lead delivery system in a patient with symptomatic paroxysmal AF with concurrent AVN ablation. |
6,399 | Cardioversion for atrial fibrillation: treatment options and advances. | Atrial fibrillation (AF) is associated with significant morbidity and mortality. There are two basic approaches to managing AF: slowing the ventricular rate, while allowing the arrhythmia to continue (the rate-control approach), and restoring and maintaining sinus rhythm (the rhythm-control approach) with antiarrhythmic drugs (AADs) and/or ablation, electrical cardioversion (CV), if needed, or both. Strategy trials comparing rate and rhythm control have found no survival advantage of one approach over the other, but other considerations, such as symptom reduction, often necessitate pursuit of rhythm control. Electrical, or direct current, CV is a widely used and effective method for termination of nonparoxysmal AF, although its success can be affected by patient- and technique-related variables. Pharmacological CV options also exist and are preferable in specific circumstances. Both pharmacological and electrical CV are associated with the risk of proarrhythmia. Many AADs are under development for both CV and maintenance of sinus rhythm. Some are atrioselective, such as vernakalant, and target ion channels in the atria, with little or no effects in the ventricle. Vernakalant, currently under Food and Drug Administration review, appears to offer a safer profile than current CV agents and is likely to expand the role of pharmacological CV. Other new AADs that provide increased efficacy or safety while maintaining normal sinus rhythm may also be better than current drugs; if so, rate-rhythm comparisons will differ from those of previous studies. In conclusion, further trials should clarify the long-term safety profiles of new atrioselective agents and other investigational drugs and define their role in the treatment of AF. |
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