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1,200 | Restitution properties during ventricular fibrillation in the in situ swine heart. | Although restitution has been hypothesized to determine action potential duration (APD) during ventricular fibrillation (VF), cardiac memory may also be important.</AbstractText>Transmembrane recordings were made with a floating microelectrode from the anterior right ventricular wall in 6 pigs during up to 60 seconds of VF. The recordings were divided into 5-second intervals, and APD60 and the diastolic interval (DI) were calculated for each activation cycle throughout each interval. Stepwise linear regression was used to determine how well each APD60 [APD60(n)] was predicted by the 4 previous DIs (n-1, n-2, n-3, n-4) and the 3 previous APD60s (n-1, n-2, n-3). A mean+/-SD of 3+/-1.5 of the variables entered the regression equation. DI(n-1) (70% of intervals) and APD60(n-1) (71% of intervals) appeared most frequently in the regression equations and were the first or second variables entered during the stepwise regression in 87% and 76% of the intervals in which they were present, respectively. The coefficients of DI(n-1) and APD60(n-1) were positive 89% and 98% of the time, respectively. R2 of the regression for all entered variables during all intervals was 0.39+/-0.05.</AbstractText>The high incidence and positive coefficient of DI(n-1) indicate that restitution is important in determining APD during VF, whereas the similarly high incidence and positive coefficient of APD(n-1) indicate that cardiac memory is equally important. The finding that the regression equation accounts for only 39% of the variability of APD indicates that factors other than restitution and memory are also important in determining APD during VF.</AbstractText> |
1,201 | Placebo-controlled, randomized clinical trial of azimilide for prevention of ventricular tachyarrhythmias in patients with an implantable cardioverter defibrillator. | Although implanted cardioverter defibrillators (ICDs) effectively treat sustained ventricular tachyarrhythmias, up to 50% of ICD recipients eventually require concomitant antiarrhythmic drug therapy to prevent symptomatic arrhythmia recurrences and hence reduce the number of device therapies.</AbstractText>A total of 633 ICD recipients were enrolled in a randomized, double-blind, placebo-controlled study to evaluate the effect of daily doses of 75 or 125 mg of azimilide on recurrent symptomatic ventricular tachyarrhythmias and ICD therapies. Total all-cause shocks plus symptomatic ventricular tachycardia (VT) terminated by antitachycardia pacing (ATP) were significantly reduced by azimilide, with relative risk reductions of 57% (hazard ratio [HR]=0.43, 95% CI 0.26 to 0.69, P=0.0006) and 47% (HR=0.53, 95% CI 0.34 to 0.83, P=0.0053) at 75- and 125-mg doses, respectively. The reductions in all-cause shocks with both doses of azimilide did not achieve statistical significance. The incidence of all appropriate ICD therapies (shocks or ATP-terminated VT) was reduced significantly among patients taking 75 mg of azimilide (HR=0.52, 95% CI 0.30 to 0.89, P=0.017) and those taking 125 mg of azimilide (HR=0.38, 95% CI 0.22 to 0.65, P=0.0004). Five patients in the azimilide groups and 1 patient in the placebo group had torsade de pointes; all were successfully treated by the device. One patient taking 75 mg of azimilide had severe but reversible neutropenia.</AbstractText>Azimilide significantly reduced the recurrence of VT or ventricular fibrillation terminated by shocks or ATP in ICD patients, thereby reducing the burden of symptomatic ventricular tachyarrhythmia.</AbstractText> |
1,202 | Is there a role for long-chain omega3 or oil-rich fish in the treatment of atrial fibrillation? | Atrial fibrillation is the most common cardiac arrhythmia in Europe and north America, and recently it was described as an epidemic. Treatment and management of this arrhythmia consists of using drugs, external electrical cardioversion and in extreme cases, internal electrical pacing. Despite treatment, this arrhythmia continues to impact on morbidity and mortality. The possible benefit from dietary interventions in relation to the primary and secondary prevention of atrial fibrillation have largely been overlooked. Our hypothesis is that increasing the intake of long-chain polyunsaturated omega3 fatty acids (LCn3) from eating a diet containing moderate amounts of oil-rich fish, will benefit people with persistent atrial fibrillation. A number of possible anti-arrhythmic actions from LCn3 have been found from animal and laboratory studies, mainly on ventricular arrhythmias. These include reducing pro-arrhythmic eicosanoids and inhibiting sodium and calcium currents. If found to be beneficial to these patients, dietary advice to eat more oil-rich fish, or take LCn3 supplements, could be part of a package of care for people with this arrhythmia. We have currently started a randomised controlled trial to test our hypothesis. |
1,203 | [Recurrent ventricular fibrillation during a febrile illness as the first manifestation of Brugada syndrome--a case report]. | A case of a 33-year-old male who was admitted to the hospital due to recurrent ventricular fibrillation during a febrile illness is presented. Initially, the patient was diagnosed with acute myocardial infarction and received thrombolytic treatment. Echocardiography and coronary angiography were normal. Right precordial ECG leads recorded one and two intercostal spaces higher than normal as well as ECG obtained following ajmaline administration revealed a typical Brugada pattern. |
1,204 | In hospital cardiac arrest: a role for automatic defibrillation. | Sudden cardiac death (SCD) survival decreases by 10% for each minute of delay in defibrillation, however, survival rates of 98% can be achieved when defibrillation is accomplished within 30s of collapse. Recently, a fully automated external cardioverter-defibrillator (AECD) was approved by the FDA for in-hospital use. The AECD can be programmed to automatically defibrillate when a life threatening ventricular arrhythmia occurs. The purpose of this study was to assess the potential impact of in-hospital AECDs on the critical time to defibrillation in monitored hospital units.</AbstractText>Mock emergency (n = 18) were conducted using simulated ventricular fibrillation in various monitored units. Observers were stationed to record the time staff responded to the arrhythmia, and the time to shock. These times were compared to an AECD protocol that defibrillates automatically in an average of 38.3 s from onset of arrhythmia (n = 18).</AbstractText>Staff versus AECD response time to arrhythmia (s) was 76.3 +/- 113.7 (CI 19.8-132.8) versus 7.6 +/- 0.6 (CI 7.3-7.9). Staff versus AECD time to shock was 169.2 +/- 103.1 (CI 117.9-220.4) versus 38.3 +/- 0.7 (CI 37.9-38.6). P-values are <0.0001 for differences between the groups.</AbstractText>The use of AECDs on monitored units would significantly reduce the critical time to defibrillation in patients with SCA. We anticipate this would translate to improved survival rates, and better neurologic outcomes.</AbstractText> |
1,205 | Impact of community-wide deployment of biphasic waveform automated external defibrillators on out-of-hospital cardiac arrest in Taipei. | To determine the impact and outcome of out-of-hospital cardiac arrests (OHCA) while using automated external defibrillators (AED) with biphasic waveforms and its effectiveness when using the Utstein Style community-wide in Taipei.</AbstractText>A one-year study was conducted to collect OHCA patients with AED utilization prospectively in Taipei City. All events and variables were recorded in the Utstein Style. Electrocardiography and voice records recovered from AED data cards were analysed. The endpoints were survival outcomes.</AbstractText>Of 653 OHCA patients with AED utilization, only 80 (12.6%) patients with 635 true arrests presented with ventricular fibrillation or tachycardia (VF/VT) as the initial rhythm. The interval between call-to-shock was 5 min longer than call-to-EMS arrival (9.3 min versus 4.0 min). Fourteen (25%) of the 55 witnessed VF/VT arrests survived to home discharge. Ninety-seven percent of shockable rhythms were successfully terminated with less than three shocks. For all OHCA patients, initial rhythm of VF/VT (OR 3.4; 95% CI = 1.2-9.4), witnessed status (OR 4.7; 95% CI = 1.3-16.6), and presence of organised rhythm irrespective of pulse during prehospital resuscitation (OR 9.2; 95% CI = 3.2-26.8) demonstrated an independent association with survival to home discharge. For VF/VT arrests, witnessed status, shorter call-to-shock time, high successful rate of the first shock, fewer averaged number of shocks delivered for each patient, and presence of an organised rhythm during prehospital resuscitation showed a likelihood to predict to predict discharged survival in univariate analysis.</AbstractText>Low frequency of VF arrests is unique to certain eastern populations but without a reduction of AED shock efficacy with biphasic waveform. Besides initial VF and witnessed status, a prehospital post-shock organized rhythm irrespective of pulse appears to be correlated to survival. Certain circumstances in a congested metropolitan city consume time to deliver shocks even after EMS arrival, and might require bystander or public access defibrillation.</AbstractText> |
1,206 | Three year longitudinal study for out-of-hospital cardiac arrest in Osaka Prefecture. | To analyze the longitudinal changes in the treatment of out-of-hospital cardiac arrests. These analyses have focused on the time interval from the receipt of call until defibrillation of patients with ventricular fibrillation.</AbstractText>Population-based, prospective longitudinal study according to the Utstein style.</AbstractText>Osaka Prefecture (population 8, 800, 000), served by 36 municipal fire and emergency departments.</AbstractText>Consecutive, out-of-hospital cardiac arrests occurring between May 1998 and April 2001.</AbstractText>Change in the interval to defibrillation, and one-year survival from cardiac arrest.</AbstractText>Of the 15,211 cases of confirmed cardiac arrests during the three years, resuscitation was attempted in 14,609 subjects. Of the 2957 cases of cardiac origin and witnessed by bystanders, 90 cases (3.0%) were alive 1 year following the episode. In 383 cases of defibrillation, the interval from receipt of call to defibrillation was evaluated annually. This interval decreased significantly during the three year course (14.5, 13.0, and 11.5 min expressed by the median), suggesting that this project to report the data of out-of-hospital arrests was an effective campaign for EMT. However, the outcome did not improve significantly during this period (3.0%, 2.6%, and 3.6% alive 1 year in witnessed arrests with cardiac etiology). This may be because the third year median duration of 11.5 min, is still insufficient to indicate a significant improvement in the outcome.</AbstractText>This project to report the data of out-of-hospital cardiac arrest might have contributed to the reduction of the interval for defibrillation, as a campaign for the EMTs; although the decrease in this interval was still insufficient to result in a significant increase in the number of cases who are alive one year later.</AbstractText> |
1,207 | Prediction of short- and long-term outcomes by electrocardiography in survivors of out-of-hospital cardiac arrest. | Programs focusing on early defibrillation have improved both short- and long-term survival of patients with VF out-of-hospital cardiac arrest (OHCA). Subsequent long-term management of survivors would be facilitated by a straight-forward, non-invasive method of identifying those at highest risk for recurrence. Therefore, we assessed the predictive value of the standard ECG to determine both short- and long-term outcomes in survivors of VF OHCA to assist in risk stratification of those patients at highest risk of sudden death.</AbstractText>All patients with an OHCA between November 1990 and December 2000 who received early defibrillation for VF in Olmsted County Minnesota (MN) were included. Cox proportional hazards modeling was used to examine ECG variables and subsequent ICD deployment and death.</AbstractText>Two hundred patients presented in VF OHCA; of these 138 (69%) survived to hospital admission (seven died in the emergency department prior to admission) and 79 (40%) were discharged. The QRS duration (141 +/- 41ms in nonsurvivors, 123 +/- 35 in survivors, P = 0.004) was predictive of short-term mortality in patients who did not survive to hospital discharge. The ventricular rate, PR interval, presence of right or left bundle branch block, QTc, ST elevation myocardial infarction, and atrial fibrillation/flutter were nonpredictive. The average length of follow up for hospital dismissal survivors was 4.8 +/- 3.0 years. In univariate analysis, each 30 ms interval increase in the QRS width and PR interval was associated with increased mortality and ICD deployment hazard ratio of 1.6 (CI 1.1-2.5, P = 0.02) and 1.12 (CI 1.0-1.2, P = 0.05), respectively. In multivariate analysis accounting for admission ejection fraction, a PR > 200 ms [HR 4.5 (CI 1.7-11.8, P = 0.022)], QRS width increase greater than 30 ms [HR 1.9 (CI 1.3-2.8, P < 0.001)], and a QRS > 120 ms [HR 2.4 (CI 1.1-5.4, P = 0.032)] were predictive of long-term mortality and ICD shocks.</AbstractText>Careful evaluation of the admitting and discharge ECG provides prognostic information for in-hospital and long-term outcomes, respectively in this cohort of out-of-hospital cardiac arrest survivors. The QRS duration on the dismissal ECG following VF OHCA provides prognostic information which might be useful to identify those at highest risk long-term, and who would benefit from more aggressive antiarrhythmic therapy and cardiac stabilization.</AbstractText> |
1,208 | Echocardiographic evidences of increased left ventricular pressure and atrial dilatation in patients with drug-resistant paroxystic atrial fibrillation and structurally normal heart. | Global myocardial index (GMI) has been significantly related to left ventricular filling pressure. We hypothesized that GMI and echographic indicators of atrial dilatation were significantly different in pAF pts compared to normals.</AbstractText>39 patients (pts) without structural heart disease, aged 52+/-10 years with pAF were compared to 36 control-matched pts aged 48+/-16 years. Following parameters were assessed: P-wave duration (Pd), GMI, left atrial dimensions (LAd=M-mode, parasternal, LAt and LAI are measurements of short and long-axis apical four chamber view), surface (LAs), volume (LAv), total ejection fraction (LA EF), right atrial dimension (RAd) and surface (RAs), total atrial surface (TAs=LAs+RAs). LAv was calculated using ellipse formula pi/6 (LAdxLAlxLAt).</AbstractText>There was no difference between the 2 groups concerning Pd (p=0.1), LA EF (p=0.23), LAd (p=0.08) and LAt (p=0.06) while the rest of the parameters were significantly higher in pAF pts: GMI: 0.5+/-0.17 vs 0.36+/-0.06 (p=0.001); LAI: 5.4+/-0.5 vs 4.5+/-0.3 cm2 (p=0.001); LAs was founded increased in pAF pts (20.6+/-5.7 vs 16.3+/-2.1 cm2, p=0.001); TAs: 40.6+/-6.9 vs 30.6+/-5.1 cm2, p=0.0001; LAv: 51.6+/-10.4 vs 37.2+/-9.3 ml (p=0.0001).</AbstractText>Although apparently without structural heart disease, pAF pts presented evidence of increased filling pressions in left ventricle and indirect markers of atrial stretch. The role of increased intra-atrial pressure in pts pFA and predictive value of these parameters need to be evaluated in a larger number of patients.</AbstractText> |
1,209 | Haemoglobin level influences plasma brain natriuretic peptide concentration. | It has been demonstrated that the haemoglobin (Hb) level is associated with the prognosis of congestive heart failure (CHF). Correction of anaemia has improved CHF outcomes even in patients without anaemia. Lower Hb level may play a more important role in left ventricular (LV) dysfunction than previously recognized. This study aimed to evaluate the association of Hb level with plasma brain natriuretic peptide (BNP) level as a marker of LV function adjusted for known determinants of BNP.</AbstractText>Association of Hb level with plasma BNP level was studied in 279 outpatients of cardiology (mean age 61 +/- 16, 54% men) using multivariate regression analysis. Mean Hb level was 13.7 +/- 1.5 g/dl and 14% of patients had anaemia. Median BNP level was 28 pg/ml (range < 4 to 580 pg/ml). In total subjects, the multivariate model adjusted for age, sex, history of CHF, atrial fibrillation, serum creatinine level, LV wall motion abnormality, end-diastolic LV dimension, LV mass index, and cardiovascular risk factors showed that a lower Hb level was significantly associated with higher BNP level (p = 0.0243). In "normal" subjects who did not have a history of CHF, atrial fibrillation, LV wall motion abnormality, LV dilatation, valvular abnormality, or LV hypertrophy, a lower Hb level was significantly associated with a higher BNP level (p = 0.0012) after adjustment for age, sex, serum creatinine level, and cardiovascular risk factors.</AbstractText>Lower Hb levels are associated with higher plasma BNP levels independent of age, sex, serum creatinine level, LV wall motion abnormality, LV hypertrophy, history of CHF, atrial fibrillation, and cardiovascular risk factors.</AbstractText> |
1,210 | Ventricular dysrhythmias in heart failure. | Left-ventricular systolic dysfunction, or heart failure (HF), is a chronic, progressive condition with a poor prognosis. Approximately 50% of deaths, especially in mild to moderate cases, are sudden. Most sudden deaths are thought to be due to ventricular tachycardia; however, premature ventricular contractions and couplets parallel severity of HF and have been associated with increased mortality risk as opposed to dysrhythmic death. Ventricular arrhythmogenesis results from many mechanisms (afterdepolarizations, reentry, and enhanced automaticity) and preconditions (electrophysiologic abnormalities, neuroendocrine activation, electrolyte imbalances, scar from an ischemic event in ischemic cardiomyopathy, fibrosis in dilated cardiomyopathy, hemodynamic abnormalities, and HF medical management). Nurses are key caregivers in optimally managing HF, either by direct actions or by using advocacy, communication, and collaboration skills to promote positive outcomes. Ventricular dysrhythmia management consists of facilitating core HF pharmacologic and nonpharmacologic medical therapies, using amiodarone to improve symptoms, as needed, and utilizing implantable cardioverter-defibrillator therapy to reduce the risk of sudden cardiac death. |
1,211 | Molecular and phenotypic effects of heterozygous, homozygous, and compound heterozygote myosin heavy-chain mutations. | Autosomal dominant familial hypertrophic cardiomyopathy (FHC) has variable penetrance and phenotype. Heterozygous mutations in MYH7 encoding beta-myosin heavy chain are the most common causes of FHC, and we proposed that "enhanced" mutant actin-myosin function is the causative molecular abnormality. We have studied individuals from families in which members have two, one, or no mutant MYH7 alleles to examine for dose effects. In one family, a member homozygous for Lys207Gln had cardiomyopathy complicated by left ventricular dilatation, systolic impairment, atrial fibrillation, and defibrillator interventions. Only one of five heterozygous relatives had FHC. Leu908Val and Asp906Gly mutations were detected in a second family in which penetrance for Leu908Val heterozygotes was 46% (21/46) and 25% (3/12) for Asp906Gly. Despite the low penetrance, hypertrophy was severe in several heterozygotes. Two individuals with both mutations developed severe FHC. The velocities of actin translocation (V(actin)) by mutant and wild-type (WT) myosins were compared in the in vitro motility assay. Compared with WT/WT, V(actin) was 34% faster for WT/D906G and 21% for WT/L908V. Surprisingly V(actin) for Leu908Val/Asp906Gly and Lys207Gln/Lys207Gln mutants were similar to WT. The apparent enhancement of mechanical performance with mutant/WT myosin was not observed for mutant/mutant myosin. This suggests that V(actin) may be a poor predictor of disease penetrance or severity and that power production may be more appropriate, or that the limited availability of double mutant patients prohibits any definitive conclusions. Finally, severe FHC in heterozygous individuals can occur despite very low penetrance, suggesting these mutations alone are insufficient to cause FHC and that uncharacterized modifying mechanisms exert powerful influences. |
1,212 | [Excessive blood loss after abdominal hysterectomy -- use of recombinant factor VIIa]. | A 38-yr-old woman suffered from excessive blood loss after elective removal of the uterus because of a leiomyoma. The surgical attempt to stop the bleeding failed. The laboratory evaluation before surgery showed normal coagulation parameters (aPTT 23.4 sec, TPZ > 100 %, platelet count 267 000/microl).</AbstractText>Despite treatment with the plasminogen activator inhibitor Tranexamic Acid (2 x 500 mg) and 10 units of concentrated platelets as well as 31 units of fresh frozen plasma and 31 units of red blood cell concentrates the bleeding continued. Reaching an cumulative blood loss of 15 000 ml the patient developed ventricular fibrillation necessitating cardiac resuscitation including defibrillation and application of epinephrine 7 mg. At this point systolic blood pressure decreased from 90 to 70 mm Hg, the core temperature was 31,9 degrees C. After successful resuscitation (systolic blood-pressure 90 mm Hg after 15 min) the bleeding started again with a blood loss of 2000 ml requiring 3 units of fresh frozen plasma and 3 red cell concentrates Use of recombinant activated Factor VII (r.FVIIa): 6 mg (300 KiU) r.FVIIa have been applied (92 microg/kgKG [4.6 KiE/kg]). Within 10 minutes the bleeding stopped. More transfusions were not necessary. The patient left the intensive care unit 8 days after the operation without neurological deficit.</AbstractText>The use of recombinant Factor VIIa may stop excessive haemorrhage, even if the cause is unknown.</AbstractText> |
1,213 | Regression of significant tricuspid regurgitation after mitral balloon valvotomy for severe mitral stenosis. | Significant tricuspid regurgitation (TR) is occasionally associated with severe mitral stenosis and has an adverse impact on morbidity and mortality in patients undergoing mitral valve surgery. However, the effect of successful mitral balloon valvotomy (MBV) on significant TR is not fully elucidated. The aim of this study was to investigate TR after MBV in patients with severe mitral stenosis.</AbstractText>We analyzed the data of 53 patients with significant TR (grade > or =2, on a 1 to 3 scale) from the mitral balloon valvotomy database at our hospital. Patients were evaluated by Doppler echocardiography before valvotomy and at follow-up 1 to 13 years after MBV. Patients were divided into group A (27 patients), in whom TR regressed by > or =1 scale, and group B (26 patients), in whom TR did not regress.</AbstractText>The Doppler-determined pulmonary artery systolic pressure was initially higher and decreased at follow-up more in group A (from 70.7 +/- 23.8 to 36.5 +/- 8.3 mm Hg; P < .0001) than in group B (from 48.7 +/- 17.8 to 41.6 +/- 13.1 mm Hg; P = NS). Compared with patients in group B, patients in group A were younger (25 +/-10 vs 35 +/- 11 years; P < .005), had higher prevalence of functional TR (85% vs 8%; P < .0001), and had lower incidence of atrial fibrillation (7% vs 38%; P < .005). Significant decrease in right ventricular end-diastolic dimension after MBV was noted in group A but not in group B. The mitral valve area at late follow-up was larger in group A than in group B (1.8 +/- 0.3 vs 1.6 +/- 0.3 cm2; P < .05).</AbstractText>Regression of significant TR after successful MBV in patients with severe mitral stenosis was observed in patients who had severe pulmonary hypertension. This improvement in TR occurred even in the presence of organic tricuspid valve disease.</AbstractText> |
1,214 | Role of a KCNH2 polymorphism (R1047 L) in dofetilide-induced Torsades de Pointes. | Various drugs are reported to prolong the QT-interval on the surface ECG, thereby increasing the risk of developing a potentially fatal arrhythmia known as Torsades de Pointes (TdP). TdP case reports for these drugs have often been associated with risk factors such as overdosing, concomitant drugs and/or existing pathophysiological conditions. A few cases appear to be devoid of these factors. To determine what role genetic variation in the hERG gene plays in drug-induced arrhythmias, we screened DNA samples collected from 105 atrial-fibrillation patients treated with dofetilide for polymorphisms, seven of whom developed TdP. An uncommon missense change, R1047L, was identified in two of seven patients who experienced TdP as compared with five of 98 individuals who were free of TdP. Included in the affected individuals was the only subject homozygous for this SNP. Cellular electrophysiological studies revealed a 10-mV positive shift in the steady-state activation curve of the 1047L hERG channel stably expressed in HEK-293 cells as compared with the wild-type (WT) channel. The activation and inactivation kinetics of the 1047L current were significantly slower than the WT (P < 0.05) at given membrane potentials. A computer simulation using a rabbit ventricular myocyte model indicated that same extent of changes in the I(Kr) channel may result in an approximately 15% prolongation in the action potential duration. Our study suggests that 1047L leads to a functional impairment of the hERG channel, which may contribute to the higher incidence of TdP in 1047L carriers when challenged with a channel blocker. |
1,215 | [Fatal suicidal intoxication with cetirizine in patient with anorexia--a case report]. | According to the best of our knowledge this is the first case of acute fatal intoxication with cetirizine published in medical literature. We have described the case of a 18-year-old female with the history of anorexia for 2 years, who was admitted to Clinic of Toxicology because of suicidal attempt with use of cetirizine. The laboratory results revealed metabolic acidosis with the pH 7.13; pO2 88 mm Hg; pCO2 36 mm Hg; HCO3 12.0 mmol/L; BE (-)17 mmol/L; SO2 100% and hypokalemia (K+ 3.1 mmol/L). On physical examination blood pressure was 70/40 mm Hg, heart rate was 36-40 beats/min. Convulsions were observed. After about two hours of intensive treatment there was a cardiac arrest in the form of ventricular fibrillation. The resuscitation procedures which lasted for over 2.5 hours were ineffective. The high dose (270 mg) of cetirizine as well as anorexia and hypokalemia could have been the cause of the unique character of the symptoms in this case. Further investigations should be carried out to confirm the safety of cetirizine in the conditions of massive intoxication and with coexistence of other risk factors. |
1,216 | Heart failure, platelet activation and inhibition of the renin-angiotensin-aldosterone system. | Heart failure is a highly prevalent disease in aging western populations, associated with a substantially increased risk of thromboembolic events, not only in severe but even in mild to moderate stages. This can partly be attributed to concomitant atrial fibrillation, a well-known risk factor for stroke, as well as a "hypercoagulable state" including formation of intraventricular thrombi. Left ventricular dysfunction results in decreased cardiac output, pulmonary congestion and neurohumoral activation with marked stimulation of the renin-angiotensin-aldosterone system. Besides its contribution to progressive left ventricular remodelling, activation of the renin-angiotensin-aldosterone system is enhanced in the development of vascular endothelial dysfunction in heart failure, resulting in decreased nitric oxide bioavailability. Nitric oxide, however, controls vascular tone and inhibits platelet activation. Enhanced platelet activation has recently been described in patients with heart failure in sinus rhythm. This article summarises the potential contribution to platelet activation of vascular endothelial dysfunction and reduced formation of the platelet inhibitor nitric oxide, which increase further the risk for thromboembolic events in heart failure. Beneficial modulation of cardiac remodelling, left ventricular function, neurohumoral activation, endothelial dysfunction and platelet activation can be achieved by inhibition of the renin-angiotensin-aldosterone system. |
1,217 | Epicardial mapping of chronic atrial fibrillation in patients: preliminary observations. | The mechanisms of chronic atrial fibrillation (AF) are not well understood. We performed epicardial mapping of chronic AF in patients undergoing open heart surgery to test the hypothesis that chronic AF is due to a left atrial "driver" with a regular, short cycle length, resulting in fibrillatory conduction to the rest of the atria.</AbstractText>Nine patients with chronic AF (1 month to >15 years' duration) were studied at open heart surgery, 8 before and 1 during cardiopulmonary bypass. During AF, atrial electrograms (AEGs) were recorded for 1 to 5 minutes from 404 epicardial electrodes arranged in bipoles along with ECG lead II or ventricular electrogram. Four-second segments of each bipolar AEG were also subjected to fast Fourier transform analysis. Two patterns of atrial activation were present during AF. In pattern 1 (7/9 patients), AEGs from parts of the atria demonstrated a short, regular cycle length with identical beat-to-beat morphology, and the rest of the atria were activated irregularly, and AEGs that demonstrated constant morphology and cycle length were localized to parts of the left atria (5/7), the right atria (1/7), or both atria (1/7). In pattern 2 (2/9 patients), AEGs showed no evidence of regular activation or constant morphology.</AbstractText>In 9 patients with chronic AF, the commonest recorded AEG pattern showed an area of regular, rapid rhythm, consistent with the possibility that a driver causing fibrillatory conduction is one mechanism of AF in these patients.</AbstractText> |
1,218 | Verification of implantable cardioverter defibrillator (ICD) interventions by nonlinear analysis of heart rate variability -- preliminary results. | Conventional ICD algorithms yield approximately 10-30% of spurious interventions. Our aim was to check whether nonlinear dynamics methods might be useful in the verification of ICD interventions.</AbstractText>We extracted 190 consecutive RR files (approximately 2000-9000 RR intervals long) from the ICDs of 70 patients (36 with coronary artery disease, 8 with hypertrophic cardiomyopathy, 19 with dilated cardiomyopathy and 7 with other diseases). The 3D phase space trajectories in delay coordinates, window pattern entropy, and algorithmic complexity of the RR intervals were examined within a 50 beat sliding window. Data were not filtered for arrhythmia and artefacts. Of the 83 recordings with appropriate interventions 79 were correctly recognised in a blind test. Two interventions were not identified in patients with fast atrial fibrillation and two in cases of complex and frequent forms of arrhythmia. There were nine spurious interventions. In all except one case (atrial fibrillation with a fast ventricular response) the analysis by nonlinear methods showed that the intervention was not necessary. All of the 98 control recordings were correctly identified in the blind test.</AbstractText>The results show that nonlinear dynamics methods may be used to supplement the existing ICD detection algorithms to enhance the detection success rate.</AbstractText> |
1,219 | An algorithm to predict implantable cardioverter-defibrillator lead failure. | The goal of this analysis was to test an algorithm that identifies implantable cardioverter-defibrillator (ICD) lead problems before clinical failure and/or inappropriate therapy.</AbstractText>The ICD lead failures typically present as inappropriate shock therapy. Identifying lead failures before their clinical presentation may prevent patient discomfort, improve device longevity, and avoid device-induced proarrhythmia.</AbstractText>We tested an algorithm that uses two measures of oversensing and one measure of abnormal impedance to detect a lead failure. The oversensing measures consisted of a counter for RR intervals <140 ms and nonsustained ventricular tachycardia episodes with mean RR interval <200 ms. The impedance measure tracked lead impedances every day and each week. Abnormal impedance was defined as a decrease in impedances or an outlier value compared with baseline. Lead failures were identified when both oversensing measures were met or abnormal impedance and one oversensing measure occurred. The stored data from 696 patients with an ICD were analyzed to determine the sensitivity and specificity of the algorithm to detect lead failures.</AbstractText>Twenty-nine patients demonstrated clinical lead failures with an average of 6 +/- 9 inappropriate shocks per patient. The two oversensing measures used in the algorithm predicted 72% (21 of 29) of the lead failures. Fulfilling at least two of the three impedance and oversensing measures, the sensitivity of our algorithm was 83% (24 of 29) with a 100% (667 of 667) specificity.</AbstractText>Oversensing combined with abnormal impedance trends may be used to identify ICD lead failures with high sensitivity and very high specificity.</AbstractText> |
1,220 | Flecainide and propafenone induced ST-segment elevation in patients with atrial fibrillation: clue to specificity of Brugada-type electrocardiographic changes. | Potent sodium channel, blockade with type IC antiarrhythmics can provoke characteristic electrocardiographic changes consistent with Brugada's syndrome in unselected patients with atrial fibrillation. In 176 treated patients, the incidence of the characteristic abnormality is small (2.3%), and thus although no ventricular arrhythmia events were observed during follow-up, the long-term clinical significance in a larger patient cohort remains to be determined. These data provide insight into the specificity of the response to type I drug administration in patients suspected of having Brugada's syndrome. |
1,221 | [Pharmacotherapy of chronic heart failure in clinical practice]. | Chronic heart failure affects between 1-5% of the population and rise steeply with age. Most patients with chronic heart failure should be routinely managed with a combination of 4 types of drugs: a diuretic, an angiotensin converting enzyme inhibitors (ACE-I), beta-blocker and usually digitalis. Diuretics are essential for symptomatic treatment when fluid overload is present, and should always be administrated in combination with ACE-I if possible. ACE-I improves survival and symptoms and reduces hospitalization in patients with moderate to severe ventricular systolic dysfunction, and in the absence of fluid retention should be given first. Angiotensin II receptor antagonist could be considered in patients who not tolerate ACE-I. beta-blocking agents are recommended for treatment of patients with stable, mild, moderate and severe heart failure unless there is a contraindication. Bisoprolol, metoprolol and carvedilol have been associated with reduction in total mortality, cardiovascular mortality and sudden death. Cardiac glycosides are indicated in atrial fibrillation and any degree of symptomatic heart failure in order slow ventricular rate. Indications for antiarrhythmic drug therapy include atrial fibrillation, non-sustained or sustained ventricular tachycardia. Oral anticoagulation reduces the risk of stroke in patients with atrial fibrillation, and there is a lack of evidence to support the use of antithrombotic therapy in patients in sinus rhythm. |
1,222 | Hemoperfusion in a child with amitriptyline intoxication. | Tricyclic antidepressant overdose is one of the most common causes of serious drug poisoning in children and adults. We report a 17-month-old girl with severe amitriptyline intoxication. She was admitted to hospital because of lethargy and seizures. It was estimated that she took approximately 75 mg/kg of amitriptyline 2 h before admission. On examination she was comatose, had ventricular tachycardia and multifocal clonic seizures. Intravenous fluid, per oral activated charcoal, diazepam, lidocaine, and sodium bicarbonate infusion were given. However, there was no response to this therapy, and the patient remained in a deep coma with cardiac arrhythmias and seizures. Hemoperfusion (HP) was performed for 2 h. During this procedure, cardioversion was used six times due to ventricular fibrillation. She had a very good clinical response to HP and no complication was observed. We suggest that HP may be an effective treatment in children with severe amitriptyline intoxication. |
1,223 | Cardiac surgery for arrhythmias. | Cardiac arrhythmia surgery was initiated in 1968 with the first successful division of an accessory AV connection for the Wolff-Parkinson-White Syndrome. Subsequent surgical procedures included the left atrial isolation procedure and the right atrial isolation procedure for automatic atrial tachycardias, discrete cryosurgery of the AV node for AV nodal reentry tachycardia, the atrial transection procedure, corridor procedure and Maze procedure for atrial fibrillation, the right ventricular disconnection procedure for arrhythmogenic right ventricular tachycardia, the encircling endocardial ventriculotomy, subendocardial resection procedure, endocardial cryoablation, the Jatene procedure, and the Dor procedure for ischemic ventricular tachycardia. Because of monumental strides in the treatment of most refractory arrhythmias by endocardial catheter techniques during the past decade, the only remaining viable surgical procedures for cardiac arrhythmias are the Maze procedure for atrial fibrillation and the Dor procedure for ischemic ventricular tachycardia. Nevertheless, the 25-30 years of intense activity in the field of cardiac arrhythmia surgery provided the essential foundation for the development of these catheter techniques and represent one of the most exciting and productive eras in the history of medicine. In one short professional career, we have witnessed the birth of arrhythmia surgery, its adolescence as an "esoteric" specialty, its prime as an enlightening yet exhausting period, and finally its waning years as a source of knowledge and wisdom on which better methods of treatment have been founded. One could hardly ask for a more rewarding experience. |
1,224 | Comparison of primary mitral valve disease in German Shepherd dogs and in small breeds. | The case records of 58 German Shepherds (GS group) affected by mitral valve prolapse (MVP) and/or mitral valve regurgitation (MR), and 49 dogs weighing < 15 kg (D group), affected by chronic valvular disease (CVD) were reviewed. The dogs of the GS group were presented more often without a detectable heart murmur (p < 0.01), and less frequently with a high intensity heart murmur (p < 0.01). Atrial fibrillation (AF) was more common in the GS group (p < 0.001). MVP associated with mitral valve thickening was more common in the D group (p < 0.001). Fractional shortening (FS) was lower (p < 0.0001) and end-systolic volume index (ESV-I) was increased (p < 0.0001) in the GS group, whereas end-diastolic volume index (EDV-I) did not differ between the 2 groups. Prevalence and severity of pulmonary hypertension were similar in the 2 groups. Dogs with mitral valve disease weighing more than 20 kg had a 5.8 higher chance of developing decreased FS, increased ESV-I, AF and ventricular arrhythmias. In the GS group, the decreased FS and increased ESV-I were not associated with the presence of AF or ventricular arrhythmias (p > 0.05). It appears that GS may be affected both by mitral valve prolapse and mitral insufficiency. It also appears that a comparatively large proportion of GS shows no major mitral valve thickening or MVP, but still presents with significant mitral regurgitation, possibly suggesting a different cause for the important incompetence observed in most cases. |
1,225 | Anterior ischemic optic neuropathy following off-pump cardiac bypass surgery. | Anterior ischemic optic neuropathy (AION) is a well-described cause of visual loss in patients who have undergone cardiac surgery with cardiopulmonary bypass. The etiology of AION following cardiac surgery with cardiopulmonary bypass is believed to be multifactorial. Microembolisation and pump-related platelet dysfunction have been considered risk factors for the development of AION following cardiac surgery with cardiopulmonary bypass. Currently, 10-15% of cardiac procedures are performed without cardiopulmonary bypass to reduce morbidity. To the best of our knowledge, this is the second report of a patient who underwent off-pump cardiac surgery and developed an AION postoperatively. The patient's potential risk factors were severe anemia, new onset of atrial fibrillation with rapid ventricular rate, hypotension postoperatively, a small optic disc, uncontrolled diabetes mellitus and a past medical history of hypertension and coronary artery disease. |
1,226 | Partial translocation for repair of left ventricular rupture after mitral valve replacement. | A new partial translocation technique to repair left ventricular rupture after mitral valve replacement and reimplant a mitral prosthesis is described. We repaired a tear from the interior by using mattress stitches buttressed with strips of Dacron felt, constructed a new annulus with a crescent-shaped piece of bovine pericardium on the left atrial wall above the repaired mitral annulus, and implanted a new prosthesis by using the newly constructed mitral annulus. We consider avoidance of mechanical stress by the prosthesis on the repaired site crucial to a successful outcome, and this new method is useful. |
1,227 | Regurgitation of the native aortic valve caused by thrombus formation after heterotopic heart transplantation. | A 61-year-old man, who had undergone heterotopic heart transplantation, had severe regurgitation through his native aortic valve develop 16 years later, which caused severe heart failure. At operation the regurgitation was found to be due to development of an organized thrombus in the sinuses of Valsalva tethering aortic leaflets. The management of this previously undescribed complication of heterotopic heart transplantation and the implications for other groups of patients (such as those receiving treatment with a left ventricular assist device) are discussed. |
1,228 | [Prevalence of atrial fibrillation and relationed factors in a population in the centre Madrid]. | Atrial fibrillation is the most common arrhythmia on clinical practice and an important risk factor for ictus. The aim of this study was to know the prevalence of this arrythmia in a central district of Madrid.</AbstractText>A retrospective study was done analysing medical records of 13,945 patients belonging to a primary care centre of Madrid. Time of study: recruitment of data from September 2000 to May 2001; analysis of data: from September 2001 to May 2002.</AbstractText>We obtained a total of 425 atrial fibrillations, 348 non-valvular and 77 valvular. Global prevalence of atrial fibrillation in patients over 40 years in our area was 2.52%. (2.47% male, 2.55% female). Risk factors for atrial fibrillation more frequently found in non-valvular were high blood pressure (HBP), diabetes, ischaemic heart disease and left ventricular dysfunction. Among valvulars we found HBP, left atrial size over 45 mm and left ventricular dysfunction.</AbstractText>Atrial fibrillation shows a prevalence and distribution in the studied area similar to that found in other European countries.</AbstractText> |
1,229 | [Alpha-linolenic acid and cardiovascular diseases]. | IMPORTANCE AND METABOLISM OF ALPHA-LINOLENIC ACID: Alpha-linolenic acid is an essential fatty acid which cannot be produced in the body and must be taken by food. Both in animals and humans, alpha-linolenic acid is desaturated and elongated into eicosapentaenoic and docosahexaenoic acid. It is also incorporated into plasma and tissue lipids and its conversion is affected by levels of linoleic acid. POTENTIAL ROLE IN PATHOGENESIS OF CARDIOVASCULAR DISEASES: Diet enriched in n-3 fatty acids, especially alpha-linolenic acid, reduces the incidence of cardiac death. Studies have shown that alpha linolenic acid prevents ventricular fibrillation which is the main cause of cardiac death. Studies in rats suggest that alpha-linolenic acid may be more effective in preventing ventricular fibrillations than eicosapentaenoic and docosahexaenoic acid. Furthermore, alpha-linolenic acid is the main fatty acid decreasing platalet aggregation which is an important step in thrombosis i.e. non-fatal myocardial infarction and stroke. DIETARY SOURCES AND NUTRITION RECOMMENDATIONS: Dietary sources include flaxseed and flaxseed oil, canola oil, soybean and soybean oil, pumpkin seed and pumpkin oil, walnuts and walnut oil. Strong evidence supports beneficial effects of alpha-linolenic acid and its dietary sources should be incorporated into balanced diet for prevention of cardiovascular diseases. The recommended daily intake is 2 g with a ratio of 5/1 for linoleic/alpha-linolenic acid. |
1,230 | Electrocardiographical case. Asymptomatic patient with ST-segment elevation. | A 46-year-old man complained of recurrent episodes of giddiness which was not associated with chest pain or breathlessness. There was no family history of sudden death. Clinical examination was unremarkable.12-lead electrocardiogram (ECG) showed ST segment elevation in the right precordial leads, with coved ST segment elevation at its J point followed by a negative T wave with no isoelectric separation, specifically in V2. These ECG features are characteristic of the Brugada syndrome. He underwent a flecanide challenge which produced further elevation of ST segment at its J point and spontaneous ventricular ectopy. Electrophysiological studies induced ventricular fibrillation with 3 extra stimuli. An implantable cardioverter-defibrillator was implanted for prevention of sudden cardiac death. The Brugada syndrome is discussed. |
1,231 | [Pharmacological versus invasive treatment in patients with atrial fibrillation]. | Aim of this prospective study was to assess quality of life (QoL), left ventricular (LV) function and exercise performance in two groups of patients (pts) with atrial fibrillation (Af) treated with: radiofrequency catheter ablation (RFA) and antiarrhythmic drugs (AA). Between 1996 and 2000 - 74 patients, 28 women, with drug refractory Af were enrolled by clinical indications for two modes of therapy: RFA and AA. RFA group consisted of 38 pts, 63.7 +/- 11.5 years old: 28 pts with RF AV Node ablation and pacemaker implantation (PI) and 10 pts with AV Node modification or right atrial isthmus RF ablation due to Af conversion to atrial flutter (Aflu) during medical therapy. AA group consisted of 36 pts, aged 59.7 +/- 13.8 years. Patients from RFA group suffered significantly more serious diseases than pts from AA group. No significant (sign.) differences between two groups were found in age, gender, arrhythmia history and number of AA taken. Pts were analyzed before entry, after 3 and 12 months of follow-up (3 mo. FU, 12 mo. FU) with following indices: LV function (Echo: EF & FS), exercise performance (treadmill test), QoL questionnaires, number of hospital admissions connected to arrhythmia or procedures (RFA & PI), number of AA drugs taken in RFA group. RFA group: Two deaths occurred due to end stage respiratory insufficiency (COPD), one pt required reposition of pacemaker lead. AA group: 3 pts required RFA due to uncontrolled Af/Aflu (AV Node ablation with PI - 1 pt, right atrial isthmus ablation - 2 pts). Analysis of two patients groups: LV function: Sign. improvement (EF & FS) in both groups in 12 mo. FU; Exercise performance: no sign. changes in 3 and 12 mo. FU. QoL: Arrhythmia scale: 3 mo. FU sign. reduction in both groups; 12 mo. FU reduction in RFA group only; Anxiety scale: 3 and 12 mo. FU sign. reduction of anxiety level in RFA group; Exercise and activity scales: 3 and 12 mo. FU sign. improvement in RFA group. During 3 and 12 mo. FU sign. less pts from RFA group required hospital admission versus pts from AA group. Sign. reduction in AA was noted in RFA group. Patients with symptomatic Af treated with RFA benefit from this kind of therapy more than patients treated with AA. Quality of life improvement visible in short term observation in patients from RFA group is still present after one year observation. Improvement in LV function is observed after one year in both groups of pts with Af. |
1,232 | Beta1-adrenergic blockade during cardiopulmonary resuscitation improves survival. | The short-acting beta1-selective adrenergic blocking agent, esmolol, was administrated during cardiopulmonary resuscitation with the hypothesis that initial resuscitation and postresuscitation survival would be improved.</AbstractText>Prospective, randomized, controlled study.</AbstractText>Animal research laboratory.</AbstractText>Male Sprague-Dawley rats.</AbstractText>Ventricular fibrillation was induced in 18 male Sprague-Dawley rats, which were then left untreated for 6 mins before attempted resuscitation with precordial compression, mechanical ventilation, and electrical defibrillation. Animals were randomized to receive 300 microg/kg esmolol in a volume of 200 microL or an equivalent volume of saline placebo during cardiopulmonary resuscitation. Electrical defibrillation was attempted after 12 mins of ventricular fibrillation.</AbstractText>Esmolol-treated animals required a significantly smaller number of electrical shocks before resuscitation. Each of the esmolol-treated but only five of nine placebo-treated animals were successfully resuscitated. Postresuscitation contractile and left ventricular diastolic functions of resuscitated animals were significantly better after esmolol administration and duration of survival was significantly increased.</AbstractText>A short-acting beta1-selective adrenergic blocking agent, when administered during cardiopulmonary resuscitation, significantly improved initial cardiac resuscitation, minimized postresuscitation myocardial dysfunction, and increased the duration of postresuscitation survival.</AbstractText> |
1,233 | Recurrent ventricular fibrillation in out-of-hospital cardiac arrest after defibrillation by police and firefighters: implications for automated external defibrillator users. | To determine the prevalence and frequency of recurrent ventricular fibrillation (VF) in patients defibrillated by police and firefighters only and to determine its relation to survival.</AbstractText>Retrospective observational study.</AbstractText>Out of hospital.</AbstractText>Individuals with witnessed VF arrest in the Rochester, MN, ambulance public service area who had defibrillatory shocks delivered by police and firefighters and return of spontaneous circulation with shocks only.</AbstractText>Electrocardiograms were recovered from data cards in automated external defibrillators used by police (n = 49) or firefighters (n = 18) to deliver shocks from December 1996 through December 2003 in the Rochester, MN, ambulance public service area. Patients with witnessed VF arrest were identified for recurrent VF after initial shock success (first one to three shocks). Both police and firefighters deployed automated external defibrillators delivering nonescalating 150-J biphasic truncated exponential waveform shocks (ForeRunner Automated External Defibrillator, Phillips/Heartstream Operation, Seattle, WA). Among 67 patients, 30 (45%) survived to neurologically intact discharge (overall performance category score of 1 in 29 patients and score of 2 in one patient). Twenty-nine patients (43%) regained spontaneous circulation with shocks only and 25 of 29 (86%) survived. VF recurred in 35 of the 67 patients (52%) while being cared for by police or firefighters. Of these 35 patients, no relation was found between the prevalence or frequency of VF recurrence and survival.</AbstractText>VF recurrence is frequent, variable in time of onset, and unrelated to the performance of bystander CPR. The prevalence and frequency of VF recurrence were unpredictable and do not adversely affect survival. Thus, vigilance for recurrent VF is essential to ensure the survival of patients who are in the care of first responders, even after initial restoration of pulses with shocks.</AbstractText> |
1,234 | Vasopressin during cardiopulmonary resuscitation: a progress report. | In patients undergoing cardiopulmonary resuscitation, circulating endogenous vasopressin concentrations were significantly higher in successfully resuscitated patients than in patients who died. These observations have prompted several investigations to assess the role of vasopressin to improve cardiopulmonary resuscitation management.</AbstractText>Literature review.</AbstractText>In the cardiopulmonary resuscitation laboratory, vasopressin improved vital organ blood flow, cerebral oxygen delivery, the probability of restoring spontaneous circulation, and neurologic recovery better than epinephrine. In pediatric preparations with asphyxia, epinephrine was superior to vasopressin, whereas in both pediatric pigs with ventricular fibrillation and adult porcine models with asphyxia, combinations of vasopressin and epinephrine proved to be highly effective. In addition, vasopressin enabled short- and long-term survival in a porcine model of uncontrolled hemorrhagic shock. In a recently published European, multiple-center trial, 1,219 adult patients with out-of-hospital cardiac arrest were randomized to receive two injections of either 40 IU of vasopressin or 1 mg of epinephrine followed by additional epinephrine if needed. The clinical study did not confirm laboratory data showing vasopressin to be more effective than epinephrine in ventricular fibrillation and pulseless electrical activity, but vasopressin was superior to epinephrine in patients with asystole. Vasopressin followed by epinephrine was more effective than epinephrine alone in the treatment of refractory cardiac arrest.</AbstractText>According to new data from the European vasopressin study, we suggest, first, the administration of 1 mg of epinephrine, followed alternately by 40 IU of vasopressin and 1 mg of epinephrine every 3 mins in adult cardiac arrest victims, regardless of the initial electrocardiographic rhythm.</AbstractText> |
1,235 | Effect of vasopressin on postresuscitation ventricular function: unknown consequences of the recent Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. | To compare the effect on postresuscitation left ventricular function of vasopressin vs. epinephrine used during cardiopulmonary resuscitation in a swine model of prolonged prehospital ventricular fibrillation.</AbstractText>Prospective, randomized experimental study.</AbstractText>University large animal resuscitation research laboratory.</AbstractText>Forty-eight swine (29 +/- 1 kg).</AbstractText>Resuscitation after 12.5 mins of untreated ventricular fibrillation, randomizing animals during cardiopulmonary resuscitation to treatment with epinephrine, vasopressin, or vasopressin followed by a vasopressin antagonist administered in the postresuscitation period.</AbstractText>Serial measurements of left ventricular systolic and diastolic function (prearrest, postresuscitation at 30 mins and 6 hrs) and 24-hr survival. Animals receiving vasopressin had more postresuscitation left ventricular dysfunction than those receiving epinephrine (p < .05). The vasopressin antagonist produced vasodilation and improved early postresuscitation left ventricular systolic and diastolic function but did not have a lasting effect on such postresuscitation ventricular function and decreased 24-hr survival compared with the use of vasopressin alone (3/16 vs. 10/16 survivors; p < .05).</AbstractText>Vasopressin use during cardiopulmonary resuscitation results in worse postresuscitation left ventricular function early but did not compromise 24-hr outcome. Reversal of vasopressin's effect with a specific V-1 antagonist in the postresuscitation period did not improve survival.</AbstractText> |
1,236 | Nonselective beta-blocking agent improves the outcome of cardiopulmonary resuscitation in a rat model. | Postresuscitation myocardial dysfunction has been recognized as a leading cause of early death after initial successful resuscitation. Recent experimental and clinical studies have indicated that the beta-adrenergic effect of epinephrine significantly increases the severity of postresuscitation myocardial dysfunction. The fact that beta-adrenergic stimulation increases myocardial oxygen consumption during ventricular fibrillation is an important implication with respect to both the exogenous in terms of pharmacologic interventions during cardiopulmonary resuscitation and the endogenous as the result of intense sympathetic activation of cardiovascular collapse. Earlier experimental evidence has indicated that oxygenation improved by beta-blockade and beta1-blocking agent did offset the adverse effect of epinephrine. This prompted us to investigate the effect of beta-blockade on both exogenous and endogenous beta stimulation in an established rat model.</AbstractText>Prospective, randomized, controlled study.</AbstractText>Animal research laboratory.</AbstractText>Male Sprague-Dawley rats.</AbstractText>In this series of studies, propranolol was administrated before ventricular fibrillation as a pretreatment combined with epinephrine treatment during precordial compression and then alone in a prolonged cardiac arrest setting.</AbstractText>Improved postresuscitation myocardial dysfunction (cardiac index, dP/dt40, -dP/dt) was observed with propranolol, a nonselective beta-adrenergic blocker, in pretreated animals such that the beneficial effects were associated with better postresuscitation survival.</AbstractText>Nonselective beta-blockade improved the outcome of cardiopulmonary resuscitation in a rat model and deserves further evaluation in settings of cardiopulmonary resuscitation.</AbstractText> |
1,237 | A new method for inducing hypothermia during cardiac arrest. | It has been shown that hypothermia induced after successful resuscitation of comatose survivors of ventricular fibrillation cardiac arrest improves survival and neurologic function. Recent studies also suggest that earlier induction of hypothermia may yield even more improvement. We sought to determine if a new pump system, in addition to vigorous external chest compression, could rapidly induce hypothermia during cardiopulmonary resuscitation in a porcine model of cardiac arrest.</AbstractText>Nine pigs (25-37 kg) were instrumented with micromanometers and thermocouple probes. Two 8-Fr catheters were placed into the femoral veins. Cardiac arrest was induced with 60-Hz current. After 5 mins of no support, chest compression was performed by a circumferential pneumatic bladder (vest-cardiopulmonary resuscitation). Blood was withdrawn from one catheter by a pump system that maximized flow by servo-control of inlet pressure, was cooled, and was returned through the other catheter. Four dogs were instrumented similarly, and cooling was performed during normal circulation.</AbstractText>In the pigs, baseline temperatures were (mean +/- SEM) 37 +/- 1 degree C. With blood cooling in the external chiller to 10 degrees C, cerebral and right atrial temperatures were reduced by 0.49 +/- 0.09 and 0.67 +/- 0.21 degrees C/min, respectively, for 10 mins. With blood cooling in the external chiller to 4 degrees C, cerebral and right atrial temperatures were reduced by 0.61 +/- 0.18 and 1.56 +/- 0.33 degrees C/min, respectively. Cerebral cooling lagged behind right atrial cooling. There was a strong correlation between coronary perfusion pressure (aortic to right atrial mean decompression-phase pressure) and cerebral cooling rate (r = .79; p < .022). Rates of cooling during normal circulation in dogs were similar.</AbstractText>Rapid induction of mild hypothermia is feasible with a system that uses venous access, standard access techniques, and external chest compression. Induction of mild hypothermia during cardiac arrest in the field appears feasible and may allow the benefit of very early induction of hypothermia to be determined in patients.</AbstractText> |
1,238 | Effects of intracerebroventricular application of brain-derived neurotrophic factor on cerebral recovery after cardiac arrest in rats. | After transient global cerebral ischemia, selective vulnerable brain areas show delayed neurodegeneration with characteristics of apoptosis. Recent data demonstrate potent neuroprotective effects of the application of endogenous growth hormones such as brain-derived neurotrophic factor (BDNF) after focal cerebral ischemia. To assess possible effects of the intracerebroventricular application of BDNF on cerebral recovery after global cerebral ischemia due to cardiac arrest in rats, various selective vulnerable brain areas were investigated.</AbstractText>Global cerebral ischemia was initiated by ventricular fibrillation in rats under general anesthesia. After 6 mins, the animals were resuscitated by external cardiac massage combined with defibrillation and divided into two groups (BDNF vs. placebo). BDNF or placebo (1 microg/hr) was applied continuously during the complete reperfusion time using an implanted osmotic minipump. After 6 hrs, 24 hrs, 3 days, and 7 days (n = 6-7 per group), coronal brain sections were analyzed by terminal deoxynucleotidyltransferase-mediated d-uracil triphosphate-biotin nick end-labeling (TUNEL) and Nissl staining and a caspase activity assay in the hippocampal cornu ammonis 1 sector, the nucleus reticularis thalami, and the striatum. At 24 hrs, 3 days, and 7 days, animals were tested according to a neurologic deficit score.</AbstractText>In all groups, typical delayed neurodegeneration was observed in selective vulnerable brain areas. Neuroscore, TUNEL, and Nissl staining revealed no relevant differences between the groups (BDNF vs. placebo) with regard to neurologic recovery and the number of viable (after 7 days in cornu ammonis 1 sector: BDNF, 110 +/- 32; placebo, 142 +/- 53) and TUNEL-positive neurons (after 7 days in cornu ammonis 1 sector: BDNF, 360 +/- 81; placebo, 253 +/- 62) during the different time points.</AbstractText>Despite the well-known neuroprotective properties of BDNF in ischemic-induced neuronal degeneration, the present study did not reveal any beneficial effects regarding neurologic recovery and neurohistopathologic outcome after global cerebral ischemia in rats. Future investigations should focus on intracellular signaling cascades activated by BDNF after global cerebral ischemia.</AbstractText> |
1,239 | Amplitude spectrum area: measuring the probability of successful defibrillation as applied to human data. | The objective of our study was to examine the effectiveness of an electrocardiographic predictor, amplitude spectral area (AMSA), for the optimal timing of defibrillation shocks in human victims of cardiac arrest. Based on the spectral characteristics of ventricular fibrillation potentials, we examined the probability of successful conversion to an organized viable rhythm, including the return of spontaneous circulation. The incentive was to predict the likelihood of successful defibrillation and thereby improve outcomes by minimizing interruptions in chest compression and minimizing electrically induced myocardial injury due to repetitive high-current shocks.</AbstractText>Observational study on human electrocardiographic recordings during cardiopulmonary resuscitation.</AbstractText>Medical research laboratory of a university-affiliated research and educational institute.</AbstractText>Victims of out-of-hospital cardiac arrest.</AbstractText>Iteration of electrocardiographic records, representing lead 2 equivalent recordings on 108 defibrillation attempts with an automated external defibrillator, of 46 victims of cardiac arrest due to ventricular fibrillation.</AbstractText>Three seconds of ventricular fibrillation, recorded immediately preceding delivery of a shock, were analyzed utilizing the AMSA algorithm. AMSA represents a numerical value based on the sum of the magnitude of the weighted frequency spectrum between 3 and 48 Hz. The greater the AMSA value, the greater was the probability of reversal of ventricular fibrillation. At an AMSA value of >13.0 mV-Hz, successful defibrillation yielded a sensitivity of .91 and a specificity of .94.</AbstractText>AMSA predicts the success of electrical defibrillation with high specificity. AMSA therefore serves to minimize interruptions of precordial compression and the myocardial damage caused by delivery of repetitive and ineffective electrical shocks.</AbstractText> |
1,240 | Attenuated adult biphasic shocks for prolonged pediatric ventricular fibrillation: support for pediatric automated defibrillators. | To evaluate published data regarding the treatment of prolonged pediatric defibrillation, with special emphasis on the use of attenuated adult biphasic shocks for pediatric defibrillation.</AbstractText>Review relevant human and animal literature.</AbstractText>Rhythm analysis algorithms from two manufacturers of automated external defibrillators can accurately distinguish shockable from nonshockable rhythms in children. Theoretical considerations and transthoracic impedance data from animals and children suggest that pediatric defibrillation doses should not necessarily vary in a simple weight-based manner. Two piglet studies have established that an attenuated adult biphasic dosage can be successfully used for 3.5- to 24-kg animals in ventricular fibrillation. One study established that the attenuated adult biphasic dosage was at least as safe and effective as the standard monophasic weight-based dosing.</AbstractText>This review supports the American Heart Association's new guidelines for pediatric automated external defibrillator usage: "Automated external defibrillators may be used for children 1 to 8 yrs of age who have no signs of circulation. Ideally the device should deliver a pediatric dose. The arrhythmia detection system used in the device should demonstrate high specificity for pediatric shockable rhythms, i.e., it will not recommend delivery of a shock for nonshockable rhythms."</AbstractText> |
1,241 | [Catheter cryoablation for the treatment of supraventricular arrhythmias]. | Catheter ablation is a radical treatment for various severe and drug-refractory arrhythmias. Radiofrequency is the reference energy for ablation, but has some limitations. Cryoenergy gradually freezes myocardial tissue, allowing the consequences to be predicted before inducing the lesion. Furthermore, the lesions are better-circumscribed and less thrombogenic than those induced by radiofrequency. Twenty-two patients (12 women) aged from 20 to 79 years with drug-refractory supraventricular arrhythmias underwent cryoablation. The ablation catheter was cooled by nitrous oxide expansion. The electrophysiological properties of the tissue are reversibly lost at a temperature of -30 degrees C, allowing cryomapping. When the appropriate target has been located, the temperature is reduced to -70 degrees C. The cryoablation is painless. The procedure was initially successful in all 12 patients with atrionodal reentrant tachycardias, usually after one or two applications. However, during the 8-month follow-up period, slower, transient tachycardia recurred in 3 patients. We observed no cases of atrioventricular (AV) block, a possible complication of radiofrequency. Cryoablation was successful and safe in two patients with an accessory pathway (Kent). In eight patients with atrial fibrillation and uncontrolled ventricular tachycardia, cryoablation was used with the aim of slowing nodal conduction. Initial success was obtained in 7 cases (3 modulations and 4 complete AV blocks) but only persisted in four cases, suggesting that more applications should be used or different sites targeted. The efficacy and safety of cryoablation make it an attractive option for the ablation of small substrates close to the nodo-Hisian tissue (atrionodal reentries and accessory pathways). New criteria must be developed to define long-term success of cryoablation of the AV node, which is successful in the acute setting. |
1,242 | Refractory ventricular fibrillation in accidental hypothermia: salvage with cardiopulmonary bypass. | A 20-year old woman presented with prolonged refractory ventricular fibrillation and pulmonary oedema following hypothermia while she was under self-administered heroin in an attempt to commit suicide. She was successfully resuscitated with cardiopulmonary bypass for core rewarming and internal defibrillation. |
1,243 | Use of implantable cardioverter defibrillators after out-of-hospital cardiac arrest: a prospective follow-up study. | Survivors of out-of-hospital cardiac arrest are at high risk of recurrent arrests, many of which could be prevented with implantable cardioverter defibrillators (ICDs). We sought to determine the ICD insertion rate among survivors of out-of-hospital cardiac arrest and to determine factors associated with ICD implantation.</AbstractText>The Ontario Prehospital Advanced Life Support (OPALS) study is a prospective, multiphase, before-after study assessing the effectiveness of prehospital interventions for people experiencing cardiac arrest, trauma or respiratory arrest in 19 Ontario communities. We linked OPALS data describing survivors of cardiac arrest with data from all defibrillator implantation centres in Ontario.</AbstractText>From January 1997 to April 2002, 454 patients in the OPALS study survived to hospital discharge after experiencing an out-of-hospital cardiac arrest. The mean age was 65 (standard deviation 14) years, 122 (26.9%) were women, 398 (87.7%) had a witnessed arrest, 372 (81.9%) had an initial rhythm of ventricular tachycardia or ventricular fibrillation (VT/VF), and 76 (16.7%) had asystole or another arrhythmia. The median cerebral performance category at discharge (range 1-5, 1 = normal) was 1. Only 58 (12.8%) of the 454 patients received an ICD. Patients with an initial rhythm of VT/VF were more likely than those with an initial rhythm of asystole or another rhythm to undergo device insertion (adjusted odds ratio [OR] 9.63, 95% confidence interval [CI] 1.31-71.50). Similarly, patients with a normal cerebral performance score were more likely than those with abnormal scores to undergo ICD insertion (adjusted OR 12.52, 95% CI 1.74-92.12).</AbstractText>A minority of patients who survived cardiac arrest underwent ICD insertion. It is unclear whether this low usage rate reflects referral bias, selection bias by electrophysiologists, supply constraint or patient preference.</AbstractText> |
1,244 | Effects of cardiac resynchronization on disease progression in patients with left ventricular systolic dysfunction, an indication for an implantable cardioverter-defibrillator, and mildly symptomatic chronic heart failure. | The effects of cardiac resynchronization therapy (CRT) in patients with mildly symptomatic heart failure have not been fully elucidated.</AbstractText>The Multicenter InSync ICD Randomized Clinical Evaluation II (MIRACLE ICD II) was a randomized, double-blind, parallel-controlled clinical trial of CRT in NYHA class II heart failure patients on optimal medical therapy with a left ventricular (LV) ejection fraction < or =35%, a QRS > or =130 ms, and a class I indication for an ICD. One hundred eighty-six patients were randomized: 101 to the control group (ICD activated, CRT off) and 85 to the CRT group (ICD activated, CRT on). End points included peak VO2, VE/CO2, NYHA class, quality of life, 6-minute walk distance, LV volumes and ejection fraction, and composite clinical response. Compared with the control group at 6 months, no significant improvement was noted in peak VO2, yet there were significant improvements in ventricular remodeling indexes, specifically LV diastolic and systolic volumes (P=0.04 and P=0.01, respectively), and LV ejection fraction (P=0.02). CRT patients showed statistically significant improvement in VE/CO2 (P=0.01), NYHA class (P=0.05), and clinical composite response (P=0.01). No significant differences were noted in 6-minute walk distance or quality of life scores.</AbstractText>In patients with mild heart failure symptoms on optimal medical therapy with a wide QRS complex and an ICD indication, CRT did not alter exercise capacity but did result in significant improvement in cardiac structure and function and composite clinical response over 6 months.</AbstractText> |
1,245 | [Role of transthoracic echocardiography in evaluation of cardiac risk in thoracic surgery]. | It is not precisely defined which group of non-cardiac surgery patients should undergo transthoracic echocardiography in preoperative preparation. This study was prospectively performed to find out whether the routine use of echocardiography is justified in patients scheduled for lung resection, and to assess its role in cardiac risk evaluation.</AbstractText>Patients classified as ASA III who were identified as having minor or intermediate predictors of cardiac risk were included in the study. Based on this triage, 130 patients underwent transthoracic echocardiography.</AbstractText>Intermediate index of increased perioperative cardiovascular risk was recorded in 36.2% and low index in 63.8% of patients. Preoperative anesthesiologic examination revealed some form of cardiac arrhythmia in 28.5%, symptoms of coronary disease in 25.4%; hypertension in 52.3%, and chronic obstructive pulmonary disease in 16.9% of patients. Transthoracic echocardiography showed the ejection fraction of 60% in 86.9% and of 40%-49% in only one patient. Left ventricular contractility was preserved in 96.2% of patients. Diastolic relaxation was weakened in 42.3% of patients. Mild mitral insufficiency was found in 29.2%; aortic stenosis in 1.5%, mild aortic insufficiency in 2.3%, mild pulmonary hypertension in 70.8%, and severe pulmonary hypertension in only 1.5% of patients. Pulmonectomy was performed in 26.9%, lobectomy in 62.3% and segmental tumor resection in 10.8% of patients. Only 26.2% of patients had peri- and postoperative complications: tachyarrhythmia and atrial fibrillation with rapid ventricular answer in 16.2%, hypotension 1.5%; hypertension in 2.3% and hypertension and arrhythmia in 1.5% of patients. Three (2.3%) patients died. None of our patients had Goldman's score higher than 25; according to Detsky index our patients belonged to 0-15 point group, class I, with the foreseen risk %.</AbstractText>Transthoracic echocardiography is not justified in the routine preoperative preparation of thoracosurgical patients classified as ASA III with clinically minor and intermediate indexes of increased cardiovascular risk. It should be done in selected patients, primarily those that have history data and clinical picture consistent with major indices of an increased cardiovascular risk.</AbstractText> |
1,246 | Echo-guided endomyocardial biopsy in heart transplant recipients. | After heart transplantation the effect of immunosuppression is monitored by histopathology of endomyocardial biopsy (EMB). EMB is usually carried out under X-ray guidance. Between January 1998 and March 2003, 1,262 biopsies were collected under echo-guidance in 156 patients. The biopsy access was gained through the internal jugular vein, by the standard catheterization technique. The average time of the procedure was 17 min. Four or five specimens were obtained from each patient, with a success rate of 96%. Complications involved two episodes of partial pneumothorax in one patient, atrial flutter in another and ventricular fibrillation in three patients. Conversion from echo to X-ray guidance was indicated in 11 patients. No case of significant tricuspid regurgitation related to the EMB procedure was recorded. The echo-guided endomyocardial biopsy appears to be a prospective alternative to the conventional approach under X-ray guidance. Its duration is comparable, it eliminates X-ray exposure, enables continuous echocardiographic monitoring and can be performed at the bedside. |
1,247 | Noninvasive assessment of right atrial pressure using Doppler tissue imaging. | Right atrial pressure (RAP) reflects volume and pressure hemodynamics of right cardiac chambers. Previous attempts for noninvasive assessment of RAP include 2-dimensional and Doppler correlates of RAP, which require the presence of optimal subcostal views that may not be always feasible. In this study we utilized Doppler tissue imaging of the tricuspid annulus in the apical 4-chamber view, for noninvasive assessment of RAP. An inverse relationship was demonstrated between mean RAP and the interval between the end of the systolic annular motion to the onset of the early diastolic filling wave (right ventricular regional isovolumic relaxation time). |
1,248 | Clinical significance of electrocardiography recordings from a higher intercostal space for detection of the brugada sign. | The significance of higher intercostal space electrocardiography (HICS ECG) for the detection of the Brugada sign was investigated.</AbstractText>The subjects consisted of 113 cases (108 males, 5 females; mean age, 57+/-17 years) with incomplete right bundle branch block type QRS morphology and ST-segment elevation (>0.10 mV) in the right precordial leads. Obvious structural heart disease was not observed in any of the subjects. The V(1-3) leads of the standard 12-lead ECG and the HICS ECG were recorded in the supine position, and the amplitude of the terminal portion of the QRS (J-point) and ST-segment (80 ms from the J-point) were measured. In the HICS ECG, there was an increase in the area in which the Brugada sign was detectable (47 leads to 66 leads), and in cases with the Brugada sign, the amplitude of the J-point increased.</AbstractText>The HICS ECG may be helpful for the detection of the Brugada sign.</AbstractText> |
1,249 | A benefit-risk assessment of class III antiarrhythmic agents. | The prevalence of arrhythmia in the population is increasing as more people survive for longer with cardiovascular disease. It was once thought that antiarrhythmic therapy could save life, however, it is now evident that antiarrhythmic therapy should be administrated with the purpose of symptomatic relief. Since many patients experience a decrease in physical performance as well as a diminished quality of life during arrhythmia there is still a need for antiarrhythmic drug therapy. The development of new antiarrhythmic agents has changed the focus from class I to class III agents since it became evident that with class I drug therapy the prevalence of mortality is considerably higher. This review focuses on the benefits and risks of known and newer class III antiarrhythmic agents. The benefits discussed include the ability to maintain sinus rhythm in persistent atrial fibrillation patients, and reducing the need for implantable cardioverter defibrillator shock/antitachycardia therapy, since no class III antiarrhythmic agents have proven survival benefit. The risks discussed mainly focus on pro-arrhythmia as torsade de pointes ventricular tachycardia. |
1,250 | [The effects of Na+ -H+ exchange inhibitor, KB-R9032, administered at the time of reperfusion in perfused rat heart]. | We have reported that pretreatment with KB-R9032, a newly developed Na+ -H+ exchange inhibitor is protective against reperfusion-induced ventricular arrhythmia in the isolated perfused rat heart. This study was conducted to elucidate whether the drug is equally effective when it is given at the time of reperfusion.</AbstractText>Male Wistar rat hearts (n=32, 16 for each group) were perfused by means of Langendorff technique. Each heart was subjected to regional ischemia (occlusion of the left anterior descending coronary artery for 11 minutes) and to three minutes of reperfusion (release of the occlusion). KB-R9032 4 mg (one shot group) or a vehicle without drug (control) were given 30 seconds before the reperfusion to 30 seconds after the reperfusion.</AbstractText>In the control group reperfusion-induced ventricular fibrillation (VF) occurred in 91.7% and the duration was 165 +/- 14.4 seconds, but, in one shot group, the incidence of VF decreased to 6.3% and the duration of VF was reduced to 0.4 +/- 0.4 seconds, respectively (P<0.05 vs control group).</AbstractText>It has been shown in this study that the Na+/H+ exchange inhibitor KB-R9032 given at the time of reperfusion suppresses reperfusion arrhythmias in the ischemia-reperfusion model of isolated rat heart.</AbstractText> |
1,251 | [Antiischemic and antiarrhythmic effect of esafosfina]. | Esafosfina, a new preparation based on fructose 1,6-diphosphate, supported the pumping ability of the heart in experiments with a 40-min occlusion followed by 60-min reperfusion of the anterior descending branch of the left coronary artery in anesthetized cats. Esafosfina also exhibited a pronounced antifibrillatory and antiarrhythmic action in anesthetized rats with ventricular fibrillation model. |
1,252 | Biventricular support with the Jarvik 2000 ventricular assist device in a calf model of pulmonary hypertension. | The Jarvik 2000 ventricular assist device (VAD) is clinically efficacious for treating end-stage left ventricular failure. Because simultaneous right ventricular support is also occasionally necessary, we developed a biventricular Jarvik 2000 technique and tested it in a calf model. One VAD was implanted in the left ventricle with outflow-graft anastomosis to the descending aorta. The other VAD was implanted in the right ventricle with outflow-graft anastomosis to the pulmonary artery. Throughout the 30 day study, hemodynamic values were continuously monitored. On day 30, both pumps were evaluated at different speeds, under various hemodynamic conditions. By gradually occluding the pulmonary artery proximally or distally, we simulated varying degrees of high pulmonary vascular resistance, right ventricular hypertension, global heart failure, or ventricular fibrillation. The two VADs maintained biventricular support even during pulmonary artery occlusion and ventricular fibrillation, yielding a cardiac output of 3-11 L/min, left ventricular end-diastolic pressure of 11-24 mm Hg, and central venous pressure of 9-25 mm Hg. End-organ function was unimpaired, and no major adverse events occurred. The dual VADs offered safe, effective biventricular assistance in the calf. Additional studies are needed to assess the effects of lowered pulse pressure upon the pulmonary circulation and to develop a single pump speed controller. |
1,253 | Atrial fibrillation after electrical shock: a case report and review. | A 52 year old man was admitted to an emergency department with a fast ventricular rate atrial fibrillation after an electrical shock. Electrical cardioversion was attempted after echocardiographic examination. This failed, but the heart rate slowed. Successful pharmacological cardioversion was achieved after 16 hours of amiodarone infusion. Pre-excitation syndrome was detected on baseline echocardiograph. Serum cardiac specific markers were all within normal limits. No abnormal findings were detected by chest radiography, echocardiographic, or coronary angiographic investigations. Acute onset atrial fibrillation after electrical injury is discussed. |
1,254 | Effects of trimetazidine on myocardial preconditioning in anesthetized rats. | Trimetazidine is a widely used anti-ischemic agent, but its effect on myocardial preconditioning in anesthetized animals has not been investigated. The aim of this study was to examine the effects of trimetazidine on ischemic preconditioning and carbachol preconditioning in anesthetized rats. Ischemic preconditioning, induced by 5-min coronary artery occlusion and 5-min reperfusion, decreased the incidence of ventricular tachycardia and abolished the occurrence of ventricular fibrillation during 30-min ischemia. Trimetazidine (10 mg/kg, i.v.) alone attenuated these parameters of arrhythmia. Carbachol infusion induced preconditioning with a marked depression of mean arterial blood pressure, heart rate and ventricular tachycardia. The marked reductions in parameters of arrhythmia induced by ischemic preconditioning and carbachol preconditioning were preserved in the presence of trimetazidine. Arrhythmia scores and myocardial infarct size were significantly reduced with ischemic preconditioning or carbachol preconditioning and were not inhibited by trimetazidine. These results show that trimetazidine protects the heart against ischemia-induced arrhythmias, reduces myocardial infarct size, preserves the effects of ischemic preconditioning and pharmacological preconditioning, and is able to mimic ischemic preconditioning in anesthetized rats. |
1,255 | Mitral Regurgitation: Current Treatment Options and Their Selection. | Mitral regurgitation (MR) is a mechanically complex hemodynamic abnormality of various etiologies that, if untreated, leads to myocardial dysfunction, heart failure, and sudden death. Unless hemodynamically severe, MR is not a major risk factor for debility and death. However, even more modest MR may impact on longevity and may create risk for thromboembolic and infectious sequelae. Currently, therapy for severe MR is surgical valve replacement or repair. When MR is not secondary to ischemic sequelae, generally accepted indications for surgery include any symptoms, left ventricular or right ventricular dysfunction or left ventricular geometric variations that reach defined levels of prognostic concern, or development of atrial fibrillation. However, low perioperative risk of repair causes some to urge surgery for severe MR irrespective of other findings. Similar controversy confounds decisions about mitral valve surgery during coronary artery bypass grafting when MR is a sequel of ischemic disease. Drug treatment has not altered MR outcome, although drugs can mitigate symptoms if surgery is contraindicated by intercurrent disease. There is no basis for prophylactic drug treatment to preserve myocardial function in asymptomatic patients. |
1,256 | Approach to Hypertrophic Cardiomyopathy. | Hypertrophic cardiomyopathy is a genetic disease characterized by marked left ventricular (LV) hypertrophy. A dynamic LV outflow obstruction is present in approximately 20% of patients. Many affected individuals remain asymptomatic throughout life, others develop heart failure symptoms or atrial fibrillation (AF), and some die suddenly, often young and in the absence of previous symptoms. Stratification of sudden death risk is based on several markers, including a previous cardiac arrest, sustained ventricular tachycardia, family history of sudden death, extreme LV hypertrophy (>/= 30 mm), syncope, nonsustained ventricular tachycardia on Holter, and abnormal exercise blood pressure response. The implantable cardioverter-defibrillator is the most effective treatment for sudden death prevention, and should be considered in patients with either one strong or multiple risk factors. Important symptoms of heart failure develop in a minority of patients, largely as a consequence of diastolic dysfunction, and are usually treated with beta blockers, or verapamil. In patients with LV obstruction and severe symptoms unresponsive to medications, myectomy operation or alcohol septal ablation is indicated for relieving the gradient and improving quality of life. AF develops in approximately 20% of patients. Amiodarone is the most effective medication for preventing AF recurrences. In chronic AF, beta blockers or verapamil are usually effective for heart rate control. The threshold for anticoagulants is low, because even brief AF episodes have a substantial embolization risk. |
1,257 | [Cardiac indications for oral anticoagulation]. | While considering long-term oral anticoagulation one should assess benefit (i.e., reduction in thromboembolic events) and risks (i.e., bleeding complications) associated with therapy for each individual patient. The classic cardiac indications for oral anticoagulation include chronic atrial fibrillation, prosthetic heart valves, and left ventricular thrombus formation following anterior myocardial infarction. The value of anticoagulation in patients with impaired left ventricular function in stable sinus rhythm and in secondary prevention of coronary artery disease remains controversial. For decades warfarin has been the only compound available. Currently, promising results have been achieved with the oral thrombin inhibitor ximelagatran. In the future, oral anticoagulants, which are administered in fixed dose with no need for monitoring of the anticoagulation level, may replace warfarin. Safety and efficacy of double antiplatelet therapy (aspirin and clopidogrel) in the secondary prevention of thromboembolic events in patients with atrial fibrillation are currently being addressed in large-scale clinical trials. |
1,258 | Wolff-Parkinson-White syndrome: essentials for the primary care nurse practitioner. | To provide nurse practitioners with a basic understanding of the pathophysiology, clinical characteristics, diagnostic methods, and management of Wolff-Parkinson-White (WPW) syndrome.</AbstractText>Selected research and clinical articles.</AbstractText>WPW syndrome is the most common form of ventricular preexcitation. The ventricular myocardium is activated earlier than expected by an accessory conduction pathway that allows a direct electrical connection between the atria and ventricles. Although many patients remain asymptomatic throughout their lives, approximately half of the patients with WPW syndrome experience symptoms secondary to tachyarrhythmias, such as paroxysmal supraventricular tachycardia, atrial fibrillation, atrial flutter, and, rarely, ventricular fibrillation and sudden death. Symptoms include palpitations, dizziness, syncope, and dyspnea. Diagnosis is usually made by electrocardiogram findings, but further testing may be warranted to confirm the diagnosis.</AbstractText>A thorough patient history and physical examination can aid the practitioner in identifying patients who may have WPW syndrome. With appropriate referral, treatment, and patient education, patients with WPW syndrome can expect to have a normal life expectancy and good quality of life.</AbstractText> |
1,259 | Brain natriuretic peptide predicts successful cardioversion in patients with atrial fibrillation and maintenance of sinus rhythm. | Brain natriuretic peptide (BNP) is released from the heart by hemodynamically induced muscle stretch. Patients with atrial fibrillation have higher levels of BNP than those in sinus rhythm.</AbstractText>To assess the usefulness of BNP as a predictor of successful cardioversion in patients with persistent atrial fibrillation and subsequent maintenance of sinus rhythm.</AbstractText>Twenty patients undergoing cardioversion for persistent atrial fibrillation were enrolled. BNP levels were measured before electric cardioversion, and 30 min and two weeks after cardioversion. Baseline echocardiograms and 12-lead electrocardiograms were obtained from all patients. Patients with valvular disease, previous mitral valve surgery or significant left ventricular dysfunction were excluded.</AbstractText>The mean BNP level and the mean heart rate were significantly higher before cardioversion than 30 min after (197+/-132 pg/mL versus 164+/-143 pg/mL, P=0.02, and 77+/-17 beats/min versus 57+/-12 beats/min, P=0.0007, respectively). Patients who reverted back to atrial fibrillation after two weeks had a baseline BNP of 293+/-106 pg/mL, while those who remained in sinus rhythm for two weeks had a lower baseline BNP of 163+/-122 pg/mL (P=0.02).</AbstractText>In patients with persistent atrial fibrillation, BNP levels are associated with successful cardioversion and maintenance of sinus rhythm two weeks after cardioversion.</AbstractText> |
1,260 | [Anti-arrhythmic effect of starfish sterol]. | To study the effect of modified starfish sterol [C03, succinic acid (5-epiandroene-17-one-3beta-ol) diester] on experimental arrhythmias.</AbstractText>Arrhythmias were induced by drugs (Aco, Oua, BaCl2 and adrenalin) i.v., ligating the left anterior descending coronary artery and electricity.</AbstractText>C03 71.4 mg x kg(-1) (ig) was shown to increase the dose of Oua inducing VP, VT, VF and CA in guinea pigs (P < 0.01); C03 (26.8, 80.4 mg x kg(-1)) was found to increase the dose of Aco inducing VF and CA in rats (P < 0.01); C03 (8.9, 26.8, 80.4 mg x kg(-1)) increase the dose of barium chloride and delay the onset time of ventricular arrhythmias (P < 0.01); C03 (14.1, 42.3 mg x kg(-10) shorten time of recovering induced by adrenalin in rabbits (P < 0.01); C03 (80.4 mg x kg(-1)) was shown to reduce the number of ventricular arrhythmias induced by coronary artery ligation in rats (P < 0.05), C03 increase VFT induced by electricity in rabbits, VFT of C03 14.1 mg x kg(-1) increased from (5.1 +/- 2.5) V to (11.0 +/- 2.7) V (P < 0.01), 42.3 mg x kg(-1) increased from (6.1 +/- 1.7) V to (15 +/- 5) V (P < 0.01).</AbstractText>Starfish sterol has anti-arrhythmic effect.</AbstractText> |
1,261 | [Case report of an unusual complication. Splenic rupture after cardiopulmonary resuscitation and thrombolysis resulted in death]. | Cardiopulmonary resuscitation (CPR) is associated with certain bleeding risks especially if thrombolysis is included in the treatment. Even though these risks are known it is not a contraindication with CPR after thrombolysis or thrombolysis after CPR. We present a case of a bleeding ruptured spleen after thrombolysis of the popliteal artery due to a occluded aneurysm in a patient with myocardial infarction and ventricular fibrillation. As for many others with this complication, the patient did not survive. |
1,262 | Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: Pacing Fast Ventricular Tachycardia Reduces Shock Therapies (PainFREE Rx II) trial results. | Successful antitachycardia pacing (ATP) terminates ventricular tachycardia (VT) up to 250 bpm without the need for painful shocks in implantable cardioverter-defibrillator (ICD) patients. Fast VT (FVT) >200 bpm is often treated by shock because of safety concerns, however. This prospective, randomized, multicenter trial compares the safety and utility of empirical ATP with shocks for FVT in a broad ICD population.</AbstractText>We randomized 634 ICD patients to 2 arms-standardized empirical ATP (n=313) or shock (n=321)-for initial therapy of spontaneous FVT. ICDs were programmed to detect FVT when 18 of 24 intervals were 188 to 250 bpm and 0 of the last 8 intervals were >250 bpm. Initial FVT therapy was ATP (8 pulses, 88% of FVT cycle length) or shock at 10 J above the defibrillation threshold. Syncope and arrhythmic symptoms were collected through patient diaries and interviews. In 11+/-3 months of follow-up, 431 episodes of FVT occurred in 98 patients, representing 32% of ventricular tachyarrhythmias and 76% of those that would be detected as ventricular fibrillation and shocked with traditional ICD programming. ATP was effective in 229 of 284 episodes in the ATP arm (81%, 72% adjusted). Acceleration, episode duration, syncope, and sudden death were similar between arms. Quality of life, measured with the SF-36, improved in patients with FVT in both arms but more so in the ATP arm.</AbstractText>Compared with shocks, empirical ATP for FVT is highly effective, is equally safe, and improves quality of life. ATP may be the preferred FVT therapy in most ICD patients.</AbstractText> |
1,263 | [Structural modification and bioactivity of cyclovirobuxine D]. | To search for new compounds for the treatment of cardiovascular diseases by structural modification of cyclovirobuxine D.</AbstractText>According to rational drug design principle, a series of cyclovirobuxine D analogues were prepared, and their bioactivities were tested.</AbstractText>Ten new compounds were syntheized and confirmed by spectra.</AbstractText>Endurance lacking oxygen activity and antiarrhythmia effects of some analogues of cyclovirobuxine D were tested. Some compounds showed better activity than cyclovirobuxine D.</AbstractText> |
1,264 | Temporal and spatial phase analyses of the electrocardiogram stratify intra-atrial and intra-ventricular organization. | We hypothesized that electrocardiogram (ECG) spatial phase analysis would define a spectrum of intracardiac organization from atrial fibrillation (AF), nonisthmus-dependent and isthmus-dependent atrial flutter (AFL) to supraventricular tachycardias (SVT), and similarly for ventricular arrhythmias. We analyzed arrhythmia ECGs of 33 patients with isthmus (n = 9) and nonisthmus (n = 5) dependent AFL and SVT: atrial (n = 3), atrioventricular nodal (n = 3), and orthodromic reciprocating (n = 3) tachycardias, as well as AF (n = 5), ventricular tachycardia (monomorphic, VT-MM; n = 7), and fibrillation (VF; n = 3). ECG spatial phase was considered coherent when the correlation coefficient of an atrial (or ventricular) template to its ECG over time maintained a constant relationship in XY, XZ, and YZ planes. Regularity was quantified spectrally from ECG and correlation series. Spatial coherence occurred in 9/9 cases of isthmus--but only 1/5 of cases of nonisthmus-dependent AFL (p < 0.01; chi2). All showed one dominant spectral peak (temporal coherence). In AF, spatial phase was inconsistent in all planes and spectra were broad band. Temporal and spatial coherence occurred in other SVT. VT-MM maintained spatial phase and a single spectral peak, while VF displayed neither. Our conclusions are that temporal and spatial phase analysis from the ECG stratifies intra-atrial and intra-ventricular organization and reveals subtle variability lost on visual inspection. |
1,265 | Exercise-provoked bidirectional ventricular tachycardia in a young woman. | Exercise-induced ventricular tachycardia (VT) is rare in children and young adults without structural heart disease. Catecholaminergic polymorphic VT (CPVT) is among the possible causes and carries a poor prognosis. The QRS morphology of CPVT can be bidirectional, polymorphic or even ventricular fibrillation. We report a case of CPVT initially presenting as sudden collapse in an 18-year-old Taiwanese woman. Family history was negative for arrhythmias and sudden death. Laboratory analyses, transthoracic echocardiography, magnetic resonance imaging, electrophysiological study including procainamide and isoproterenol test were all negative. Bidirectional VT was induced by treadmill exercise test. She responded well to beta-blocker therapy. Some cases of CPVT are sporadic and some occur in patients with a family history. The treatment of choice for this disease is beta-blocker and implantation of an internal cardioverter defibrillator. |
1,266 | [Stroke and other tromboembolic complications in atrial fibrillation. Part I. Prevalence and risk factors]. | In a series of papers the authors discuss problems of epidemiology and drug prevention of stroke and other thromboembolic complications in patients with atrial fibrillation. Part I contains data on frequency of strokes in different categories of patients as well as review of main risk factors and mechanisms of development of stroke and other systemic embolic complications in various types of atrial fibrillation. Application of transthoracic and transesophageal echocardiography for assessment of risk of stroke and other systemic emboli is also discussed. |
1,267 | [Simple cardiovascular reflex test during hospitalization due to myocardial infarction predicts sudden but not non-sudden cardiac death during 2 years follow up]. | Prognostic significance of heart rate (HR) response to easy to perform provocative maneuvers such as Valsalva maneuver and deep breath requires further elucidation.</AbstractText>Valsalva maneuver with calculation of Valsalva ratio (VR) and deep breath test with calculation of difference between average maximal and minimal HR during first minute of test (HRD) were performed in 210 patients on days 4-11 of myocardial infarction (MI). This analysis included data from 188 patients (68,1% men, age 34-75 years, 93.6% on beta-blockers during test).</AbstractText>During period of follow up for 2.1+/-0.8 years there were 9 sudden (SD) and 13 non-sudden (non-SD) cardiac deaths. ROC-analysis allowed to determine optimal prognostic values of VR (<1.13) and HRD (<3.36) for SD. For non-SD these values could not be determined. According to univariate logistic regression analysis predictors of SD were as follows: VR<1.13 (OR 7.8, 95% CI 1.6-39.0, p=0.012), HRD <3.36 (OR 4.3, 95%CI 1.1-16.9, p=0.034), history of MI, ventricular fibrillation during first 24 h of MI, clinical heart failure (NYHA class II-III) on the day of tests. At multivariate analysis independent predictors of SD were history of MI (OR 8.3, 95% CI 1.5-46.2, p=0.015), ventricular fibrillation during first 24 h of MI (OR 72.3, 95% CI 5.1-1032.9, p=0.002) and VR <1.13 (OR 7.36, 95% CI 1.3-41.7, p=0.024). Univariate predictors of non-SD included history of MI, history of heart failure, HR on admission and postinfarction angina. HR on admission >/= 91 bpm was the single independent predictor of non-SD (OR 3.8, 95% CI 1.1-13.0, p=0.034).</AbstractText>Valsalva ratio <1.13 on days 4-11 of MI in patients with sinus rhythm and without severe heart failure was associated with high risk of SD but not of non-SD during 2 years of follow up.</AbstractText> |
1,268 | Ephedrine increases ventricular arrhythmias in conscious dogs after myocardial infarction. | This study examined the hypothesis that the sympathomimetic activity of ephedrine increases the risk of lethal arrhythmias.</AbstractText>The sympathomimetic amine, ephedrine, is used to augment physical performance and as a weight loss aid, but little is known about the cardiovascular consequences in individuals with ischemic heart disease.</AbstractText>Fifteen dogs at low risk for ventricular fibrillation (VF) during exercise and transient myocardial ischemia 30 days after a small anterior myocardial infarction were retested after five days of ephedrine use (Xenadrine, 0.4 mg/kg/day orally). To assess the effects of ephedrine on cardiac autonomic control, baroreceptor reflex sensitivity (BRS), heart rate (HR) variability, HR response to acute myocardial ischemia, and resting catecholamines were measured before and after ephedrine. Dogs were used as their own control when possible.</AbstractText>Nine of 15 animals had increased ventricular arrhythmias during ephedrine treatment (p = 0.01) and four had VF. Three dogs that had VF could not be resuscitated. Five animals with increased arrhythmias during ephedrine treatment had none during a third exercise and ischemia test after drug washout. Heart rates were higher after 30 s of myocardial ischemia during ephedrine treatment (204 +/- 25 beats/min no drug vs. 218 +/- 26 beats/min with ephedrine, p = 0.03). All plasma catecholamines increased after ephedrine administration. No changes in BRS, HR variability, or exercise HR were noted.</AbstractText>Ephedrine increases ischemia-dependent arrhythmias at doses recommended in over-the-counter preparations. Increased arrhythmia risk was associated with augmented ischemia-dependent sympathetic reflex activation.</AbstractText> |
1,269 | Safety of dobutamine stress transesophageal echocardiography in obese patients for evaluation of potential ischemic heart disease. | The purpose of this study was to determine the safety of dobutamine stress transesophageal echocardiography (DS-TEE) in the evaluation of potential coronary artery disease in obese patients. Obese patients tend to have a higher prevalence of hypertension, coronary artery disease, and sleep apnea conditions that could potentially predispose to complications during endoscopic procedures such as DS-TEE. In addition, obese patients are more likely to have oxygen desaturation during upper gastrointestinal endoscopy. Thus, the safety of DS-TEE in 90 obese patients (body mass index (BMI) > or = 27.5 kg/m2) and 86 nonobese patients (BMI < 27.5 kg/m2) was compared. Minor complications (i.e., complications of transient duration and requiring no or only simple intervention) occurred with almost equal frequency in the nonobese and obese groups (28% vs. 29%, P = ns). Transient hypotension was observed in 9% of the obese group compared to 22% in the nonobese group (P < 0.025). However, transient hypertension was noted in 20% of the obese patients compared to 6% in the nonobese group (P < 0.01). A major complication occurred in three obese patients (3.3%), which included hypotension, marked elevation of systolic blood pressure, or ventricular fibrillation. Four patients (4.7%, P = ns) of the nonobese group had a major complication, which included sustained ventricular tachycardia in one, hypertension in one, and hypotension in two patients. No deaths occurred in either group. Although obesity should remain a consideration in the risk assessment of whether or not to perform DS-TEE, when proper precautions are instituted DS-TEE appears equally safe in obese as compared to nonobese patients. |
1,270 | Deaths due to hunger strike: post-mortem findings. | Hunger strike is described as voluntary refusal of food and/or fluids. Prolonged starvation may produce many adverse events including even death in rare circumstances. Here, we present three fatal cases (all males, 25-38 years) died from hunger strike. In all corpses, obvious muscle wasting with reduced subcutaneous and internal fat deposits, and atrophy in some organs were demonstrated at autopsy. The extraordinary long starvation period before death could presumably be linked to the thiamine uptake in this period, which had been discontinued by all subjects before the death occurred. Prolonged caloric deficiency with subsequent complications such as multiple organ failure, severe sepsis and ventricular fibrillation could account as major causes of death in these subjects. The competence of the physicians working with hunger strikers about the processes and potential problems is of great importance since they have to acknowledge about them to their patients. |
1,271 | Association of stage of left ventricular diastolic dysfunction with P wave dispersion and occurrence of atrial fibrillation after first acute anterior myocardial infarction. | The aim of this study was to investigate the association of stage of left ventricular diastolic dysfunction after acute myocardial infarction (AMI) with P maximum, P dispersion, and atrial fibrillation (AF) occurrence rate.</AbstractText>The occurrence of AF following AMI is frequently associated with a left ventricle restrictive filling pattern. Increased P dispersion is also associated with the occurrence of AF after AMI. But, the relation between the stage of left ventricular diastolic dysfunction and the P wave measurements after AMI has not yet been investigated.</AbstractText>Electrocardiograms of 90 patients with first anterior AMI were recorded on admission, and P wave measurements were performed. The left ventricular diastolic functions were evaluated by transthoracic echocardiography. On the basis of mitral inflow, subjects were stratified into three left ventricular diastolic filling patterns. All patients were monitored continuously for the detection of AF in the Coronary Care Unit.</AbstractText>Thirty patients had a normal filling pattern (33.3%) (NF group), 37 had impaired relaxation (41.1%) (IR group), and 23 had pseudonormal/restrictive filling pattern (25.6%) (PN/R group). P maximum was longer in the PN/R group (103 +/- 12 ms) compared with the NF group (94 +/- 9 ms, P = 0.019), but no significant difference was found between PN/R and IR (96 +/- 13 ms, P > 0.05) groups, and between NF and IR groups (P > 0.05). There was no significant difference for P minimum among the groups (P > 0.05). P dispersion was longer in the PN/R group (35 +/- 6 ms) than in the NF (26 +/- 7 ms, P < 0.001) and IR groups (26 +/- 6 ms, P < 0.001), but not different between the NF and IR groups (P > 0.05). Occurrence of AF was significantly more frequent in the PN/R group (52.2%) than in the NF (16.7%, P = 0.007) and IR groups (10.8%, P = 0.001). Frequency of AF was not different between the NF and IR groups (P > 0.05). In multivariate analyses, the stage of diastolic dysfunction was independently associated with P maximum, P minimum, P dispersion, and the occurrence of AF (P < 0.001, P = 0.035, P < 0.001, and P = 0.002, respectively).</AbstractText>P maximum and P dispersion are increased, and AF occurrence risk is higher in patients with pseudonormal/restrictive filling pattern after first anterior AMI. The stage of diastolic dysfunction is an independent predictor of P wave measurements and AF occurrence.</AbstractText> |
1,272 | Two hearts and one defibrillator. | A patient who had undergone heterotopic heart transplantation and placement of an implantable cardioverter defibrillator in his native heart underwent generator change. Defibrillation testing induced ventricular fibrillation in his donor heart. To prevent this potentially lethal complication, defibrillator shock therapy must be synchronized to the donor heart R wave. |
1,273 | Adaptation of cardiac action potential durations to stimulation history with random diastolic intervals. | The restitution hypothesis proposes that adaptation of cardiac action potential duration (APD) to rate changes is a predictor of ventricular fibrillation (VF). Conventional restitution kinetics plots the APD of a premature beat as a function of the previous diastolic interval (DI), and VF vulnerability is related to how rapidly APD shortens with decreasing DI. However, APD depends not only on the previous DI but also on the history of previous APDs and DIs. For a comprehensive understanding of APD restitution, we developed a random stimulation protocol and curve fitted each APD with the previous DIs and APDs using multiple autoregressive analyses.</AbstractText>Guinea pig hearts (n = 5) were perfused and stained with di-4 ANEPPS to record optical APs from 252 sites. Activation and repolarization times were detected in real time from one pixel and hearts were stimulated at random DIs (range 0-50 or 0-100 ms). We found that the first, second, and third previous APDs and DIs are required to obtain the best curve fit, which provides the most significant feedback control to APD and up to six previous beats contributed to curve fits (R > 0.8). The coefficients relating the previous DI to APD increased systematically in going from apex to base reflecting the intrinsic gradient of APD across the epicardium.</AbstractText>Random restitution is more comprehensive than steady-state restitution, being based on random and dynamic DIs, and makes possible characterization of restitution in only 32 seconds to track changes in restitution during time-varying conditions such as ischemia/reperfusion.</AbstractText> |
1,274 | Effects of ablation, digitalis, and beta-blocker on dual atrioventricular nodal pathways and conduction during atrial fibrillation. | Modification of AV nodal conduction by radiofrequency ablation (RFA) results in a variable reduction in heart rate during atrial fibrillation (AF). Using AF induced in patients with dual AV nodal pathways as a model, we tested the effect of additional treatment with digitalis (ouabain) and beta-blocker (esmolol).</AbstractText>Ten patients were randomized to control (group I) and studied only before ablation. AF was induced in 30 patients before and after slow pathway ablation (group II). Mean ventricular cycle lengths (AF CLmean) were recorded. Slow pathway conduction was eliminated after ablation in 10 patients (group IIA), whereas slow pathway conduction was still present in 20 patients (group IIB). Compared to pre-RFA there was a 10% increase in AF CLmean post-RFA (P < 0.01). During isoproterenol infusion the increase was 8% (P = NS). Adding digitalis and beta-blocker during isoproterenol infusion increased AF CLmean by 75% (95% in group IIA) compared to 36% in group I (P < 0.001 II vs I).</AbstractText>Slow pathway ablation reduces ventricular rate during AF. Addition of digitalis and beta-blocker during isoproterenol infusion significantly decreases ventricular rate after ablation compared to the control group. The finding suggests that beta-blocker has significant effects on fast AV nodal pathway conduction during induced AF with isoproterenol infusion.</AbstractText> |
1,275 | Magnetic resonance imaging findings in patients with Brugada syndrome. | Cardiac magnetic resonance imaging (CMR) is a powerful diagnostic tool for evaluating cardiac structure and function. Recently, right ventricular wall-motion abnormalities were described using electron beam tomography in patients with Brugada syndrome. In the present study, we prospectively evaluated CMR findings in patients with Brugada syndrome compared to matched controls.</AbstractText>CMR was performed on 20 consecutive patients with proven Brugada syndrome. The imaging protocol included breath-hold dark blood prepared T1-weighted multislice turbo spin-echo and gradient-echo images. Ventricular volumes and dimensions were compared to age- and sex-matched normal volunteers. The right ventricular outflow tract area was significantly enlarged in patients with Brugada syndrome compared to controls (11 vs 9 cm2, P = 0.018). There was a trend to larger right ventricular end-diastolic and end-systolic volumes and lower right ventricular ejection fraction in patients with Brugada syndrome compared to controls. However, none of the differences reached significance (P = 0.3, P = 0.08, and P = 0.06, respectively). There was no statistically significant difference in the left ventricular parameters between patients and controls. High intramyocardial T1 signal similar to fat signal was observed in 4 (20%) of the 20 patients compared to none of the controls.</AbstractText>The findings support the view that subtle structural changes, such as right ventricular outflow tract dilation may point to a localized arrhythmogenic substrate in patients with Brugada syndrome.</AbstractText> |
1,276 | Presence of intermittent J waves in multiple leads in relation to episode of atrial and ventricular fibrillation. | Brugada syndrome is characterized by J wave and ST-segment elevation of right precordial leads and causes idiopathic ventricular fibrillation. We experienced a patient of Brugada syndrome with prominent J wave and ST-segment elevation not only in V(1) to V(3) but also in many leads. He suffered spontaneous ventricular fibrillation and resuscitated by direct current. He has no structural heart disease. |
1,277 | Mild hypothermia during prolonged cardiopulmonary cerebral resuscitation increases conscious survival in dogs. | Therapeutic hypothermia during cardiac arrest and after restoration of spontaneous circulation enables intact survival after prolonged cardiopulmonary cerebral resuscitation (CPCR). The effect of cooling during CPCR is not known. We hypothesized that mild to moderate hypothermia during CPCR would increase the rate of neurologically intact survival after prolonged cardiac arrest in dogs.</AbstractText>Randomized, controlled study using a clinically relevant cardiac arrest outcome model in dogs.</AbstractText>University research laboratory.</AbstractText>Twenty-seven custom-bred hunting dogs (19-29 kg; three were excluded from outcome evaluation).</AbstractText>Dogs were subjected to cardiac arrest no-flow of 3 mins, followed by 7 mins of basic life support and 10 mins of simulated unsuccessful advanced life support attempts. Another 20 mins of advanced life support continued with four treatments: In control group 1 (n = 7), CPCR was with normothermia; in group 2 (n = 6, 1 of 7 excluded), with moderate hypothermia via venovenous extracorporeal shunt cooling to tympanic temperature 27 degrees C; in group 3 (n = 6, 2 of 8 excluded), the same as group 2 but with mild hypothermia, that is, tympanic temperature 34 degrees C; and in group 4 (n = 5), with normothermic venovenous shunt. After 40 mins of ventricular fibrillation, reperfusion was with cardiopulmonary bypass for 4 hrs, including defibrillation to achieve spontaneous circulation. All dogs were maintained at mild hypothermia (tympanic temperature 34 degrees C) to 12 hrs. Intensive care was to 96 hrs.</AbstractText>Overall performance categories and neurologic deficit scores were assessed from 24 to 96 hrs. Regional and total brain histologic damage scores and extracerebral organ damage were assessed at 96 hrs. In normothermic groups 1 and 4, all 12 dogs achieved spontaneous circulation but remained comatose and (except one) died within 58 hrs with multiple organ failure. In hypothermia groups 2 and 3, all 12 dogs survived to 96 hrs without gross extracerebral organ damage (p < .0001). In group 2, all but one dog achieved overall performance category 1 (normal); four of six dogs had no neurologic deficit and normal brain histology. In group 3, all dogs achieved good functional outcome with normal or near-normal brain histology. Myocardial damage scores were worse in the normothermic groups compared with both hypothermic groups (p < .01).</AbstractText>Mild or moderate hypothermia during prolonged CPCR in dogs preserves viability of extracerebral organs and improves outcome.</AbstractText> |
1,278 | Cooled ablation. | Research on cooled ablation has been evolving for the last 10 years. Findings and current applications are reviewed. A cooled ablation catheter is approved by the FDA for use in idiopathic ventricular tachycardia (VT) patients, based on data originally submitted by Cardiac Pathways, Inc. This technology has subsequently been used by the clinicians in atrial flutter cases, nonischemic VT, epicardial accessory pathways, and atrial fibrillation. The experience at Johns Hopkins suggests that cooled radiofrequency ablation has utility in a variety of situations and in some instances has come to be the ablation system of choice. |
1,279 | Focal origin of ventricular fibrillation in a patient with ischemic cardiomyopathy. | A 65-year-old patient with history of ischemic cardiomyopathy admitted to the hospital for chest pain and subsequently experienced incessant ventricular fibrillation (VF), requiring repeated defibrillation. Coronary angiogram was unchanged, compared to a study a year before, and acute ischemia was not considered to be the etiology of the VF. A particular premature ventricular contraction morphology was noted on telemetry prior to each episode of VF. The patient subsequently underwent successful radiofrequency ablation of a focus in the left ventricular free wall. Careful examination of initiating foci of VF or polymorphic ventricular tachycardia, with radiofrequency ablation in appropriate cases, could be potentially life-saving. |
1,280 | IgD myeloma with systemic amyloidosis with chest discomfort as an initial symptom. | A 53-year-old man was admitted to Keio University Hospital because of serious dyspnea and edema of the lower extremities. Eighteen months previously, the patient had complained of chest discomfort, and was then admitted for the first time to our hospital for evaluation of chest pain. Electrocardiography showed poor R wave progression in leads Vl through V4, and diffuse nonspecific ST-segment and T wave abnormalities with low voltage. However, no definitive diagnosis could be made at this initial admission and a calcium-channel blocker was prescribed. Despite this treatment, the patient was readmitted with worsening dyspnea and lower extremity edema. The diagnosis of heart failure and nephritic syndrome was made at the second admission. In addition, immunoelectrophoresis showed a monoclonal IgD (lambda) M protein and increased plasma cells in the bone marrow, suggesting a diagnosis of multiple myeloma. The patient was thus given dexamethasone (20 mg per day for 4 days) intravenously, but his symptoms did not improve. Two weeks later, the patient deteriorated further with congestive heart failure and renal failure, and subsequently died of cardiac arrest with ventricular fibrillation. On autopsy, IgD (lambda)-positive plasma cell proliferation was found in the bone marrow, confirming the diagnosis of multiple myeloma. In addition, amyloid deposition was detected in various organs including the heart, kidneys, esophagus, duodenum, ileum, colon, tongue, and lungs. In particular, the weight of the heart was 650 g demonstrating a hypertrophic septum and amyloid deposition in the myocardium and even coronary arteries. In summary, the final diagnosis was IgD (lambda) multiple myeloma associated with systemic amyloidosis. |
1,281 | Atrial fibrillation after surgical correction of mitral regurgitation in sinus rhythm: incidence, outcome, and determinants. | The incidence, determinants, and outcome of postoperative atrial fibrillation (AF) after surgery for mitral regurgitation (MR) are poorly defined but may have important implications for timing of mitral valve surgery.</AbstractText>In 762 patients in sinus rhythm with no AF history undergoing MR surgical correction, we examined the rates and prognostic implications of postoperative AF for early AF (within 2 weeks postoperatively) and late AF (>2 weeks after surgery). During postoperative follow-up, 180 patients (24%) experienced new AF (early AF in 136 and late AF in 111). Isolated early AF without recurrence was observed in 69 patients characterized by high angina class and lower left ventricular ejection fraction but no significant left atrial (LA) enlargement. However, overall early AF predicted late AF: 62+/-5% of patients with early AF had late AF at 10 years compared with 9+/-1% of patients without early AF (P<0.0001). Large LA size strongly and independently predicted early AF (P=0.01) and late AF (P=0.003). For late AF, the predictive value of an enlarged LA was cumulative to that of early AF. Postoperative AF was associated with an increased subsequently higher risk of stroke or congestive heart failure (adjusted risk ratio=1.46 [1.04 to 2.05], P=0.03).</AbstractText>Postoperative AF is common after surgical correction of MR in patients with no prior history of AF and is associated with increased subsequent morbidity. LA enlargement is independently predictive of postoperative AF and as such, should be integrated into the clinical decision-making process in patients with MR.</AbstractText> |
1,282 | Role of IKur in controlling action potential shape and contractility in the human atrium: influence of chronic atrial fibrillation. | The ultrarapid outward current I(Kur) is a major repolarizing current in human atrium and a potential target for treating atrial arrhythmias. The effects of selective block of I(Kur) by low concentrations of 4-aminopyridine or the biphenyl derivative AVE 0118 were investigated on right atrial action potentials (APs) in trabeculae from patients in sinus rhythm (SR) or chronic atrial fibrillation (AF).</AbstractText>AP duration at 90% repolarization (APD90) was shorter in AF than in SR (300+/-16 ms, n=6, versus 414+/-10 ms, n=15), whereas APD20 was longer (35+/-9 ms in AF versus 5+/-2 ms in SR, P<0.05). 4-Aminopyridine (5 micromol/L) elevated the plateau to more positive potentials from -21+/-3 to -6+/-3 mV in SR and 0+/-3 to +12+/-3 mV in AF. 4-Aminopyridine reversibly shortened APD90 from 414+/-10 to 350+/-10 ms in SR but prolonged APD90 from 300+/-16 to 320+/-13 ms in AF. Similar results were obtained with AVE 0118 (6 micromol/L). Computer simulations of I(Kur) block in human atrial APs predicted secondary increases in I(Ca,L) and in the outward rectifiers I(Kr) and I(Ks), with smaller changes in AF than SR. The indirect increase in I(Ca,L) was supported by a positive inotropic effect of 4-aminopyridine without direct effects on I(Ca,L) in atrial but not ventricular preparations. In accordance with the model predictions, block of I(Kr) with E-4031 converted APD shortening effects of I(Kur) block in SR into AP prolongation.</AbstractText>Whether inhibition of I(Kur) prolongs or shortens APD depends on the disease status of the atria and is determined by the level of electrical remodeling.</AbstractText> |
1,283 | Effect of simvastatin and antioxidant vitamins on atrial fibrillation promotion by atrial-tachycardia remodeling in dogs. | There is evidence for a role of oxidant stress and inflammation in atrial fibrillation (AF). Statins have both antioxidant and antiinflammatory properties. We compared the effects of simvastatin with those of antioxidant vitamins on AF promotion by atrial tachycardia in dogs.</AbstractText>We studied dogs subjected to atrial tachypacing (ATP) at 400 bpm in the absence and presence of treatment with simvastatin, vitamin C, and combined vitamins C and E. Serial closed-chest electrophysiological studies were performed in each dog at baseline and 2, 4, and 7 days after tachypacing onset. Atrioventricular block was performed to control ventricular rate. Mean duration of induced AF was increased from 42+/-18 to 1079+/-341 seconds at terminal open-chest study after tachypacing alone (P<0.01), and atrial effective refractory period (ERP) at a cycle length of 300 ms was decreased from 117+/-5 to 76+/-6 ms (P<0.01). Tachypacing-induced ERP shortening and AF promotion were unaffected by vitamin C or vitamins C and E; however, simvastatin suppressed tachypacing-induced remodeling effects significantly, with AF duration and ERP averaging 41+/-15 seconds and 103+/-4 ms, respectively, after tachypacing with simvastatin therapy. Tachypacing downregulated L-type Ca2+-channel alpha-subunit expression (Western blot), an effect that was unaltered by antioxidant vitamins but greatly attenuated by simvastatin.</AbstractText>Simvastatin attenuates AF promotion by atrial tachycardia in dogs, an effect not shared by antioxidant vitamins, and constitutes a potentially interesting new pharmacological approach to preventing the consequences of atrial tachycardia remodeling.</AbstractText> |
1,284 | Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin. | The rate of stroke in atrial fibrillation (AF) depends on the presence of comorbid conditions and the use of antithrombotic therapy. Although adjusted-dose warfarin is superior to aspirin for reducing stroke in AF, the absolute risk reduction of warfarin depends on the stroke rate with aspirin. This prospective cohort study tested the predictive accuracy of 5 stroke risk stratification schemes.</AbstractText>The study pooled individual data from 2580 participants with nonvalvular AF who were prescribed aspirin in a multicenter trial (Atrial Fibrillation, Aspirin, Anticoagulation I study [AFASAK-1], AFASAK-2, European Atrial Fibrillation Trial, Primary Prevention of Arterial Thromboembolism in patients with nonrheumatic Atrial Fibrillation in primary care study, and Stroke Prevention and Atrial Fibrillation [SPAF]-III high risk or SPAF-III low risk). There were 207 ischemic strokes during 4887 patient-years of aspirin therapy. All schemes predicted stroke better than chance, but the number of patients categorized as low and high risk varied substantially. AF patients with prior cerebral ischemia were classified as high risk by all 5 schemes and had 10.8 strokes per 100 patient-years. The CHADS(2) scheme (an acronym for Congestive heart failure, Hypertension, Age >75, Diabetes mellitus, and prior Stroke or transient ischemic attack) successfully identified primary prevention patients who were at high risk of stroke (5.3 strokes per 100 patient-years). In contrast, patients identified as high risk by other schemes had 3.0 to 4.2 strokes per 100 patient-years. Low-risk patients identified by all schemes had 0.5 to 1.4 strokes per 100 patient-years of therapy.</AbstractText>Patients with AF who have high and low rates of stroke when given aspirin can be reliably identified, allowing selection of antithrombotic prophylaxis to be individualized.</AbstractText> |
1,285 | Absence of clinically important HERG channel blockade by three compounds that inhibit phosphodiesterase 5--sildenafil, tadalafil, and vardenafil. | Compounds that inhibit phosphodiesterase 5 (PDE5) have been developed for the treatment of erectile dysfunction. Because men with erectile dysfunction frequently have comorbid cardiovascular disease, they may have limited cardiac repolarization reserve and be at risk of arrhythmia if treated with medications that prolong ventricular repolarization. The human ether-a-go-go related gene (HERG) channel is important for repolarization in human myocardium and is a common target for drugs that prolong the QT interval. We studied the ability of three compounds that inhibit PDE5--sildenafil, tadalafil, and vardenafil--to block the HERG channel. Using a whole cell variant of the patch-clamp method, the HERG current was measured in a stably transfected human embryonic kidney cell line expressing the HERG channel. The compounds produced dose-dependent reductions in HERG current amplitude over a concentration range of 0.1 to 100 microM. The IC50 values were 12.8 microM for vardenafil and 33.3 microM for sildenafil. Because the maximum soluble concentration of tadalafil (100 microM) produced only a 50.9% inhibition of the HERG current amplitude, the IC50 value for tadalafil could not be determined with the Hill equation. Tadalafil had the weakest capacity to block the HERG channel, producing a 50.9% blockade at the maximum soluble concentration (100 microM), compared with 86.2% for vardenafil (100 microM) and 75.2% for sildenafil (100 microM). In conclusion, the concentrations of the PDE5 inhibitors required to evoke a 50% inhibition of the HERG current were well above reported therapeutic plasma concentrations of free and total compound. None of the three compounds was a potent blocker of the HERG channel. |
1,286 | Value of immediate postoperative electrocardiogram to update risk stratification after major noncardiac surgery. | Current consensus guidelines recommend postoperative electrocardiographic surveillance only in patients at relatively high risk of postoperative major cardiac complications, but the usefulness of electrocardiograms after major noncardiac surgery is unknown. We prospectively studied 3,570 patients who underwent major noncardiac procedures and had electrocardiograms performed in the recovery room. Rates of major cardiac complications (acute myocardial infarction, pulmonary edema, ventricular fibrillation or primary cardiac arrest, and complete heart block) were higher in patients who had new postoperative electrocardiographic abnormalities consistent with ischemia (ST-T elevation or depression or T-wave abnormalities compatible with ischemia) compared with those without ischemia (6.7% vs 1.9%, p <0.001). Multivariate analysis, after adjusting for pre- and intraoperative clinical data, indicated that the presence of ischemia on the immediate postoperative electrocardiogram was an independent predictor of major cardiac complications (odds ratio 2.2, 95% confidence interval 1.2 to 3.9, p <0.01). When patients were stratified by a preoperative Revised Cardiac Risk Index, ischemia on the immediate postoperative electrocardiogram identified patients with a higher risk of major cardiac complications in low- and high-risk subsets (odds ratio 4.9, 95% confidence interval 1.6 to 15 in lower risk patients; odds ratio 2.0, 95% confidence interval 1.0 to 3.7 in higher risk patients). We conclude that the immediate postoperative electrocardiogram is a valuable tool to adjust risk stratification, even in patients who have lower risks when undergoing noncardiac surgery. |
1,287 | Comparison of outcomes of white versus black patients hospitalized with heart failure and preserved ejection fraction. | Black patients who have heart failure (HF) may have a larger proportion of HF with preserved ejection fraction (PEF) than white patients because of the greater prevalence and severity of hypertension and left ventricular hypertrophy in blacks. However, studies have not systematically evaluated differences by race in patients who have HF-PEF compared with those who have systolic HF (SHF). Therefore, we examined baseline characteristics and long-term outcomes in patients who had HF-PEF compared with those who had SHF, with an emphasis on variation by race, in a biracial cohort of patients treated within the Veterans Health Administration health care system. In a cohort of 448 patients (192 blacks and 256 whites) hospitalized with HF, 27% had HF-PEF. The proportion of HF-PEF was similar in black (25%) and white (29%) patients (p = 0.4). Among patients who had SHF, black patients were younger, had lower prevalences of atrial fibrillation and diabetes, and had less co-morbidities than white patients, whereas there were no significant differences in these variables by race in patients who had HF-PEF. However, among patients who had SHF or HF-PEF, blacks had a lower prevalence of coronary disease, higher systolic and diastolic blood pressures, and higher serum levels of creatinine than white patients. In addition, mortality and readmission rates for HF did not differ by race among patients who had HF-PEF. Overall, patients who had HF-PEF had a high morbidity rate (30% patients were readmitted for HF in </=6 months) and a high mortality rate (44% at 3 years), despite the use of angiotensin-converting enzyme inhibitors by 66% of patients at discharge. This underscores the importance of evaluating other agents for the treatment of patients who have HF-PEF. |
1,288 | Dysrhythmias and the athlete. | Young competitive athletes are perceived by the general population to be the healthiest members of society. The possibility that highly trained high school and college athletes may have a potentially serious cardiac condition that can predispose to life-threatening dysrhythmias or sudden cardiac death (SCD) seems paradoxical. The occurrence of SCD in young athletes from dysrhythmias is an uncommon but highly visible event. Media reports of sudden death in athletes have intensified the public and medical interest in medical, ethical, and legal issues related to cardiac disorders in the athlete. Developing screening strategies to identify conditions associated with sudden death has been the focus of attention of experts in the fields of arrhythmology and sports medicine and has resulted in Consensus Statements and Guidelines for evaluation of athletes. These guidelines provide information and recommendations for detection, evaluation, and management of athletes with cardiovascular disorders and criteria for eligibility and disqualification from participation in high-intensity and competitive sports. Differentiating normal exercise-induced physiologic changes in the heart from pathological conditions associated with sudden death is critical for developing screening strategies to identify athletes at high risk. This article discusses a case report of sudden cardiac death in an athlete followed by a brief review of various causes of cardiac dysrhythmias in young athletes and recommendations for screening and management of athletes with cardiovascular diseases. |
1,289 | Risk stratification and primary prevention of sudden cardiac death: sudden death prevention. | The initial challenge in primary prevention of sudden cardiac death (SCD) lies in identifying those at greatest risk, before the index event. Ventricular fibrillation is the leading cause of SCD; however, many clinical conditions predispose fatal ventricular dysrhythmias. In patients with structural heart disease, left ventricular dysfunction is the strongest predictor of SCD. Noninvasive markers such as nonsustained ventricular tachycardia, delayed potentials, decreased heart rate variability and baroreflex sensitivity, and repolarization alternans are further observed to assess risk in ischemic cardiomyopathy; however, most of these markers have poor positive predictive value and lack specificity. The electrophysiologic study has strong positive predictive value, but remains a costly and invasive method for risk stratification. In patients with normal hearts, genetic predisposition may identify patients at risk but clinical markers are not readily recognized. The implantable loop recorder is a useful tool in detecting dysrhythmic causes of syncope and identifying patients at risk for SCD. |
1,290 | Cardiac pacing device therapy for atrial dysrhythmias: how does it work? | Atrial fibrillation (AF) is the most common dysrhythmia in North America. Paroxysmal or persistent AF affects an estimated 2.8 million individuals, causes significant morbidity, and is associated with 1 billion dollars in healthcare costs each year in the United States. An aging population, the prevalence of hypertension, and the emergence of heart failure as the final common pathway of heart disease finds us in an age where the incidence of AF is ever increasing and the management challenges are indeed an expanding clinical problem. Although guidelines for selection of the appropriate pacing mode have been published, device therapy for the control of AF and paroxysmal AF is an emerging clinical management strategy. In 2001 The American College of Cardiology (ACC)/American Heart Association (AHA) published a document to revise the 1998 guidelines for device therapy, and even now these guidelines require elucidation and inclusion for the use of cardiac pacing device therapy for the control of atrial dysrhythmia. Choosing a complex system, in particular for the patient with persistent and symptomatic atrial dysrhythmia, is a most intricate challenge for the healthcare professional and the healthcare system. Rate dependent effects on refractoriness, reduction of ectopy, remodeling of the substrate, and prevention of pauses have been described as the potential mechanisms responsible for the rhythmic control effect attributed to atrial pacing. However, while permanent cardiac pacing is required for patients with symptomatic bradycardia with atrioventricular block and AF, the concept of pacing for the primary prevention of AF is novel. Pacing algorithms, single site, biatrial, and dual-site atrial pacing and site-specific pacing have all been studied as substrate modulators to prevent recurrent atrial dysrhythmia.A dilemma exists surrounding the primary approach for the control of symptomatic AF with rapid ventricular response. The question remains: should it be to maintain the sinus rhythm or to control the ventricular response rate to the AF and anticoagulate? Variations in the population studied, differences in the pacing algorithms and protocols, and a lack of definitive end points account for the variable results of the studies completed thus far. With the current data available, it appears that for individuals with sinus node dysfunction and paroxysmal AF in combination with a bradyarrhythmia indication for pacing, suppression algorithms may play an additive role with full atrial pacing in the management and reduction of episodes and burden of paroxysmal AF. The goal of these therapies is to reduce the symptoms and hopefully decrease the healthcare costs associated with paroxysmal and persistent AF with uncontrolled ventricular response. |
1,291 | Cardiac defibrillation and resynchronization therapies: principles, therapies, and management implications. | Patients with heart failure remain at high risk for sudden cardiac death (SCD) and death due to heart failure progression, despite the incorporation of pharmacologic agents into clinical practice that have been shown to decrease mortality in clinical trials. Most patients experience SCD as their first dysrrhythmic event. The implantable cardioverter defibrillator (ICD) effectively terminates ventricular tachycardia/fibrillation (VT/VF) aborting SCD. Cardiac resynchronization therapy (CRT) complements pharmacologic therapy improving cardiac performance, quality of life, functional status, and exercise capacity in patients with systolic dysfunction despite optimal medical therapy who have a prolonged QRS duration; furthermore, it decreases mortality when compared with optimal medical therapy alone. Implantation of a combination CRT and ICD device, a CRT-D, reduces mortality by aborting SCD and providing the functional benefits of CRT. This article discusses the evolution of CRT-D therapy, the mechanism of operation of a CRT-D device, and nursing implications. |
1,292 | Myocarditis: emergency department recognition and management. | Myocarditis is an acute inflammatory syndrome involving the heart and related structures. In many instances, the presentation is obvious, and appropriate treatment and disposition follow accordingly. In other situations, patients present with viral illness of the respiratory or gastrointestinal tracts (or both) or nonspecific symptoms such as fatigue and weakness,leading the clinician astray. Management is largely supportive, including aggressive cardiorespiratory support. |
1,293 | Dimensionality in cardiac modelling. | The development of mathematical models of the heart has been an ongoing concern for many decades. The initial focus of this work was on single cell models that incorporate varyingly detailed descriptions of the mechanisms that give rise to experimentally observed action potential shapes. Clinically relevant heart rhythm disturbances, however, are multicellular phenomena, and there have been many initiatives to develop multidimensional representations of cardiac electromechanical activity. Here, we discuss the merits of dimensionality, from 0D single cell models, to 1D cell strands, 2D planes and 3D volumes, for the simulation of normal and disturbed rhythmicity. We specifically look at models of: (i) the origin and spread of cardiac excitation from the sino-atrial node into atrial tissue, and (ii) stretch-activated channel effects on ventricular cell and tissue activity. Simulation of the spread of normal and disturbed cardiac excitation requires multicellular models. 1D architectures suffer from limitations in neighbouring tissue effects on individual cells, but they can (with some modification) be applied to the simulation of normal spread of excitation or, in ring-like structures, re-entry simulation (colliding wave fronts, tachycardia). 2D models overcome many of the limitations imposed by models of lower dimensionality, and can be applied to the study of complex co-existing re-entry patterns or even fibrillation. 3D implementations are closest to reality, as they allow investigation of scroll waves. Our results suggest that 2D models offer a good compromise between computational resources, complexity of electrophysiological models, and applicability to basic research, and that they should be considered as an important stepping-stone towards anatomically detailed simulations. This highlights the need to identify and use the most appropriate model for any given task. The notion of a single and ultimate model is as useful as the idea of a universal mechanical tool for all possible repairs and servicing requirements in daily life. The ideal model will be as simple as possible and as complex as necessary for the particular question raised. |
1,294 | Benefit-risk assessment of tolterodine in the treatment of overactive bladder in adults. | Overactive bladder is associated with symptoms of urgency, with or without urge incontinence, usually with daytime frequency and nocturia in the absence of local pathological factors. Muscarinic receptor antagonists (antimuscarinics) are the first-line pharmacotherapy. Tolterodine, a competitive, nonselective antimuscarinic specifically developed for the treatment of overactive bladder, demonstrated tissue selectivity for the bladder over the parotid gland in an animal model. As of March 5, 2003, the immediate-release (IR) formulation had been approved in 72 countries and the extended-release (ER) formulation had been approved in 28 countries, and tolterodine had been administered to 5 million patients. This review evaluates the benefit-risk profile of tolterodine in the treatment of adults with overactive bladder, summarising clinical trial and postmarketing surveillance data. Tolterodine has been found to significantly reduce micturition frequency, urgency perception and the number of episodes of urge incontinence and increase the volume voided per micturition. Dry mouth, an antimuscarinic class effect, is the most commonly reported adverse effect but is mostly mild to moderate in severity. Serious adverse effects are reported infrequently. Based on summary and review of postmarketing surveillance and clinical trial safety data received by the market authorization holder and contained in the Periodic Safety Update Reports for tolterodine, several monitored serious events of the gastrointestinal tract (e.g. ileus or haemorrhage), nervous system (e.g. syncope, convulsions and memory disorders) and cardiovascular system (e.g. ventricular arrhythmia, atrial fibrillation, palpitations, bradycardia, transient ischaemic attacks and hypertension) were not considered related to tolterodine. QT or corrected QT (QTc) prolongation was not observed in any of the five cases of verified ventricular arrhythmia in patients administered tolterodine; there is insufficient evidence to indicate that tolterodine causes ventricular arrhythmia or extrasystoles or any specific type of cardiac rhythm abnormality. The safety profile of tolterodine is similar in patients aged > or =65 years and in younger adults. Clinically relevant drug interactions are limited to cytochrome P450 3A4 inhibitors, such as ketoconazole, and co-administration with such agents warrants a tolterodine dosage decrease. In addition, tolterodine IR 2mg twice daily is similar in efficacy to oxybutynin IR 5mg three times daily, and tolterodine ER 4 mg once daily is similar in efficacy to oxybutynin ER 10mg once daily. Dry mouth occurred less frequently with tolterodine than oxybutynin, and moderate to severe dry mouth occurred more than three times less frequently. Based on the low frequency of adverse events, the absence of unexpected adverse events and the very low frequency of serious adverse events, we conclude that tolterodine is a well tolerated treatment for overactive bladder in adults, in whom it should be considered as first-line therapy. |
1,295 | Mother rotors and the mechanisms of D600-induced type 2 ventricular fibrillation. | Two types of ventricular fibrillation (VF) have been demonstrated in isolated rabbit hearts during D600 infusion. Type 1 VF is characterized by the presence of multiple, wandering wavelets, whereas type 2 VF shows local spatiotemporal periodicity. We hypothesized that a single mother rotor underlies type 2 VF.</AbstractText>One (protocol I) or 2 (protocol II) cameras were used to map the epicardial ventricular activations in Langendorff-perfused rabbit hearts. Multiple episodes of type 2 VF were induced in 22 hearts by high-concentration (> or =2.5 mg/L) D600 (protocol I). During type 2 VF, a single spiral wave (n=19) and/or an epicardial breakthrough pattern (n=11) was present in 14 hearts. These spiral waves either slowly drifted or intermittently anchored on the papillary muscle (PM) of the left ventricle. Dominant-frequency (DF) analyses showed that the highest local DF was near the PM (12.5+/-1.1 Hz). There was an excellent correlation between the highest local DF of these spiral waves and breakthroughs (11.8+/-1.7 Hz) and the DF of simultaneously obtained global pseudo-ECG (11.2+/-1.8 Hz, r=0.97, P<0.0001) during type 2 VF. We also successfully reproduced the major features of type 2 VF by using the Luo-Rudy action-potential model in a simulated, 3-dimensional tissue slab, under conditions of reduced excitability and flat action-potential duration restitution.</AbstractText>Either a stationary or a slowly drifting mother rotor can result in type 2 VF. Colocalization of the stationary mother rotors with the PM suggests the importance of underlying anatomic structures in mother rotor formation.</AbstractText> |
1,296 | Conditions leading to pediatric cardiology consultation in a tertiary academic hospital. | To determine the basis for cardiac consultations for pediatric patients in an academic hospital setting.</AbstractText>The activities of the cardiology consultation service were tabulated for 12 months, from July 2001 to June 2002. Patients were identified from 4 sources, ie, a monthly log of patient encounters maintained by the consultation service, encounter forms submitted to the billing office, consultation notes maintained in a central file, and a departmental list of echocardiography studies. Patients who required clearance for noncardiac surgical procedures were generally evaluated in the cardiology clinic and not by the consultation service. Patient data were obtained from consultation and echocardiography reports and from hospital computer-based records for discharge summaries for inpatient admissions, emergency department encounter summaries, and laboratory reports. For each patient, consultations were tabulated as separate encounters if they occurred on different days in the emergency department, during separate admissions, or for different clinical concerns during a single admission.</AbstractText>A total of 2071 consultations were performed for 1724 patients. The age at the time of consultation was 6.6 +/- 9.3 years (median: 1.2 years; range: 1 day to 60.6 years). A total of 1507 patients (87.4%) had a single consultation; 217 patients (12.6%) had multiple encounters, ranging from 2 to 9, accounting for 564 consultations (27.2%). Clinical concerns included murmurs (18.5%), cardiac function (12.7%), arrhythmias (12.7%), intercurrent illnesses among cardiac patients (11.3%), cyanosis (6.3%), syndromes (5.7%), chest pain (5.2%), syncope/dizziness (4.5%), subacute endocarditis (4.4%), follow-up evaluations of fetal diagnoses (4.3%), Kawasaki disease (3.4%), cor pulmonale (3%), recent cardiac surgery or catheterization (1.6%), cerebrovascular accidents (1.2%), and miscellaneous conditions. Four diagnoses accounted for 91% of murmur evaluations, ie, patent ductus arteriosus, ventricular septal defects, innocent murmurs, and pulmonary branch murmur of infancy. The most common murmur diagnosis in the neonatal intensive care unit was patent ductus arteriosus (68%), in the well-child nursery was ventricular septal defect (64%), and on the medical ward was innocent murmur (62%). The most common basis for evaluation of function was oncologic disease. Among patients evaluated for function, there were 3 new diagnoses of structural congenital heart disease, all involving neonates with aortic arch obstruction. Approximately two-thirds of arrhythmias were supraventricular in origin. The most common arrhythmias requiring treatment were supraventricular tachycardia and atrial flutter/fibrillation, the latter occurring mainly among older patients with structural heart disease. Diagnoses made with fetal echocardiography accounted for 14.3% of newborn consultations and included 83% of patients with cyanotic cardiac disease. Three syndromes accounted for 57% of consultations for this indication, ie, VACTERL association (vertebral anomalies, anal atresia, congenital heart disease, tracheoesophageal fistula, renal abnormality, and limb anomalies), trisomy 21, and infant of diabetic mother. Chest pain and syncope/dizziness were frequently evaluated in the emergency department and, in this setting, accounted for 13 and 10% of all evaluations and 19 and 25% of evaluations for new patients, respectively. For patients evaluated for chest pain, the most common basis was musculoskeletal/costochondritic (42%) or idiopathic (22%). There was a cardiac or pericardial basis in 11% of cases; these patients either had known heart disease associated with this complication or systemic symptoms, abnormal cardiac auscultatory findings, and electrocardiographic features of pericarditis. Syncope/dizziness most commonly had a vasovagal (50.5%) or orthostatic (24.7%) basis. There was a cardiac basis in 5.4% of cases; these patients were more likely to have symptoms associated with exercise. Although endocarditis was a frequent clinical concern (91 patients), only 3 cases were identified, involving 2 patients with structural heart disease and 1 neonate with an indwelling intracardiac catheter. Two other patients had central venous lines, intravascular thrombus, and fungemia. Kawasaki disease was the most common acquired condition leading to consultation. Cor pulmonale was most commonly screened among patients with congenital diaphragmatic hernia, chronic lung disease of prematurity, pneumonitis, reactive airway disease, or cystic fibrosis. Patients with recent cardiac surgery or cardiac catheterization typically had postpericardiotomy syndrome or complications associated with vascular access. Approximately 20% of cases of cerebrovascular accidents had a cardiac basis.</AbstractText>Although a variety of conditions were assessed, some were encountered more frequently. Future educational curricula developed for cardiac training of pediatric residents should appropriately emphasize conditions necessitating consultation.</AbstractText> |
1,297 | Simultaneous biplane single-beat assessment of left ventricular systolic function in patients with atrial fibrillation. | Left ventricular systolic function was studied in 40 patients with atrial fibrillation using a matrix-array transducer, which enables 2 simultaneous orthogonal views to be obtained in a biplane mode. Bland-Altman analysis showed excellent correlation and agreement between the systolic parameters of a single beat with identical RR1 and RR2 intervals and the measured average value over all cardiac cycles. |
1,298 | Effects of ventricular rate regularization pacing on quality of life and symptoms in patients with atrial fibrillation (Atrial fibrillation symptoms mediated by pacing to mean rates [AF SYMPTOMS study]). | The aim of this study was to investigate the effect of the Ventricular Response Pacing (VRP) algorithm, which regularizes ventricular rate during atrial fibrillation (AF), on symptoms, quality of life, and functional capacity. VRP regularizes the ventricular rate during AF without increasing the mean ventricular rate, thereby reducing the severity of AF-related symptoms in patients with persistent AF. However, VRP did not improve general quality of life (Medical Outcomes Study 36-item Short-Form General Health Survey), the performance of routine activities (Duke Activity Status Index), or functional capacity (hall walk) in patients with AF. |
1,299 | QT interval variability and spontaneous ventricular tachycardia or fibrillation in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients. | This study aimed to determine whether increased QT interval variability is associated with an increased risk for ventricular tachycardia (VT) or ventricular fibrillation (VF), documented by interrogation of the implantable cardioverter-defibrillator (ICD), in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II.</AbstractText>Unstable repolarization has been proposed as a risk factor for re-entrant arrhythmias, but confirmatory data from clinical trials are lacking.</AbstractText>The QT variability was assessed in 10-min, resting high-resolution electrocardiogram recordings at study entry using a semiautomated algorithm that measured beat-to-beat QT duration in 817 MADIT II patients. The incidence of VT/VF requiring device therapy was determined by ICD interrogation.</AbstractText>Median normalized QT variability (QTVN) was 0.179 and 0.125, respectively, in patients with VT/VF versus those without VT/VF (p = 0.001); QTVI (QTVN adjusted for heart rate variance) also was significantly (p < 0.05) higher in VT/VF patients than in those without VT/VF. Either QTVN or QTVI was linked with a significantly higher probability of VT/VF: two-year risk of VT/VF from Kaplan-Meier curves was 40% in highest quartile versus 21% in lower quartiles for QTVN, and 37% versus 22% for QTVI (p < 0.05 for each). In multivariate Cox regression models adjusting for clinical covariates (race, New York Heart Association functional class, time after myocardial infarction), top-quartile QTVI and QTVN were independently associated with VT/VF (hazard ratio for QTVN 2.18, 95%confidence interval [CI] 1.34 to 3.55, p = 0.002; hazard ratio for QTVI 1.80, 95% CI 1.09 to 2.95, p = 0.021).</AbstractText>In postinfarction patients with severe left ventricular dysfunction, increased QT variability, a marker of repolarization lability, is associated with an increased risk for VT/VF.</AbstractText> |
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