Search PubMed⌕ Search

Biomedical subjects

M Zehender

Publications and source records attributed to M Zehender.

At least 55 records · Page 3Linked to original sources
PubMed1993

Right ventricular infarction as an independent predictor of prognosis after acute inferior myocardial infarction.

BACKGROUND: Acute inferior myocardial infarction frequently involves the right ventricle. We hypothesized that right ventricular involvement, as diagnosed by ST-segment elevation in the right precordial lead V4R, may affect the prognosis of patients with inferior myocardial infarctions. METHODS: In 200 consecutive patients admitted to the hospital with acute inferior myocardial infarctions, we assessed the prevalence and diagnostic accuracy of ST-segment elevation in lead V4R (as compared with four other diagnostic procedures) to identify right ventricular involvement and its prognostic implications for in-hospital and long-term outcomes. RESULTS: The in-hospital mortality after inferior myocardial infarction was 19 percent, and major complications occurred in 47 percent of the patients. The presence of ST-segment elevation in lead V4R in 107 patients (54 percent) was highly predictive of right ventricular infarction (sensitivity, 88 percent; specificity, 78 percent; diagnostic accuracy, 83 percent), as compared with the other diagnostic procedures. The patients with ST-segment elevation in lead V4R had a higher in-hospital mortality rate (31 percent vs. 6 percent, P < 0.001) and a higher incidence of major in-hospital complications (64 percent vs. 28 percent, P < 0.001) than did those without ST-elevation in V4R. Multiple logistic-regression analysis showed ST elevation in V4R to be independent of and superior to all other clinical variables available on admission for the prediction of in-hospital mortality (relative risk, 7.7; 95 percent confidence interval, 2.6 to 23) and major complications (relative risk, 4.7; 95 percent confidence interval, 2.4 to 9). The post-hospital course (follow-up, at least 1 year; mean follow-up, 37 months) was similar in patients with and in those without electrocardiographic evidence of right ventricular infarction. CONCLUSIONS: Right ventricular involvement during acute inferior myocardial infarction can be accurately diagnosed by the presence of ST-segment elevation in lead V4R, a finding that is a strong, independent predictor of major complications and in-hospital mortality. Electrocardiographic assessment of right ventricular infarction should be routinely performed in all patients with acute inferior myocardial infarctions.

Adult↗
PubMed1992

[Cardiac interactions between ketanserin and the calcium antagonist nifedipine].

Ketanserin and calcium antagonists are frequently used for the treatment of arterial hypertension in the elderly. The possibility that combined treatment with ketanserin and the calcium antagonist nifedipine have a pro-arrhythmic effect was investigated in 20 normal volunteers aged > 60 years with normal or slightly elevated blood pressure. Each subject received monotherapy with ketanserin or nifedipine for 1 week and the combined treatment during the following week. Clinical and biochemical parameters, ECG and 24-hour ECG recording were monitored before and at the end of the first and second treatment weeks. Ketanserin and nifedipine given in monotherapy or in combination did not modify, on average, blood pressure, heart rate, the biochemical variables and the QT interval. In the 24-hour ECG recordings, 2 normal subjects developed a marked increase in the frequency of ventricular ectopics, couplets and ventricular tachycardia after combined treatment. Therefore, the present investigation does not exclude the possibility that combined treatment with ketanserin and nifedipine could increase the prevalence of arrhythmia in some elderly patients.

Aged↗
PubMed1992

Effects of amiodarone versus quinidine and verapamil in patients with chronic atrial fibrillation: results of a comparative study and a 2-year follow-up.

Rapid, reliable and safe reestablishment of sinus rhythm is the major aim of pharmacologic treatment in patients with chronic atrial fibrillation. The mainstay of therapy in this arrhythmia has been quinidine. More recently, amiodarone was shown in non-comparative studies to be superior to class IA agents under certain conditions. In 40 patients with atrial fibrillation persisting for 4 weeks up to 2 years, the efficacy and safety of either quinidine and verapamil (days 1 to 3, quinidine 1,500 mg/day; days 4 to 6, quinidine 1,500 mg + verapamil 240 mg/day) or amiodarone therapy (days 1 to 3, amiodarone 1,200 mg/day intravenously; days 4 to 14, amiodarone 800 mg/day orally) were randomly examined. Responders continued on their effective medication for 3 months. Thereafter, all patients were treated with a fixed regimen of quinidine (480 mg/day) plus verapamil (240 mg/day) for up to 2 years. During atrial fibrillation, quinidine reduced mean ventricular cycle length by 40 ms (-5%), quinidine and verapamil increased mean cycle length by 57 ms (8%) and amiodarone by 192 ms (28%, p less than 0.01). In addition, quinidine and verapamil had a characteristic "rate-smoothing" effect on atrioventricular conduction during atrial fibrillation. The rhythm was converted to sinus rhythm after quinidine in 5 (25%) of 20 patients and after the combination of quinidine and verapamil in 11 (55%) of 20 patients. Amiodarone restored sinus rhythm in 12 (60%) of 20 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone↗
PubMed1992

Short-term and long-term treatment with propafenone: determinants of arrhythmia suppression, persistence of efficacy, arrhythmogenesis, and side effects in patients with symptoms.

OBJECTIVE: To assess the clinical criteria predicting the short and long-term efficacy of propafenone, an agent with class IC antiarrhythmic activity and a broad pharmacological profile. DESIGNS: Prospective study of propafenone at doses of 450 to 900 mg/day during a six week dose titration period (including a placebo phase with two separate 24 Holter recordings). Responders to treatment were followed for one year. PATIENTS: One hundred patients with frequent ventricular arrhythmias (greater than 30 extrasystoles/h) of Lown class III and IVA/B and without evidence of myocardial infarction within the past six months. ANALYSIS: Multivariate regression analysis of spontaneous arrhythmia variability and of different clinical variables to determine the short and long-term efficacy and safety of propafenone. MEASUREMENTS AND MAIN RESULTS: Propafenone 450 mg/day was effective in 30/100 patients (30%), and at 600 mg/day another 14 responded. The efficacy of propafenone correlated with a low spontaneous arrhythmia variability and, as shown by multivariate analysis, with a lower patient age (p less than 0.05). When the dose was increased to 900 mg/day a further six (12%) patients responded. However, with increasing doses of propafenone, the one year probability of effective treatment decreased from 86% (450 mg/day) to 67% (600 mg/day) and to 44% (900 mg/day). After restudying the patients at three, six, and 12 months and after dose adjustment in 11/44 patients (25%), 31 patients (70%) remained responders. Loss of permanent antiarrhythmic efficacy was best predicted by the initial dose that achieved a response. No patient died suddenly or had arrhythmogenic effects during Holter monitoring. Side effects occurred in 36% of patients but these rarely limited long-term treatment. CONCLUSIONS: A younger age, low spontaneous arrhythmia variability, and particularly a low titration dose were the best predictors of the short and long term efficacy of propafenone. All other responders should have repeated Holter recordings during the first year of treatment.

Adult↗
PubMed1992

Prevalence, circumstances, mechanisms, and risk stratification of sudden cardiac death in unipolar single-chamber ventricular pacing.

BACKGROUND: Permanent cardiac pacing is well established for the improvement of prognosis and quality of life in patients with severe bradycardia. However, sudden cardiac death still remains an unresolved problem, as it occurs in approximately 20-30% of paced patients. This 2-year follow-up study was directed at prospectively assessing prevalence, circumstances, and mechanisms of sudden death in 2,021 permanently paced patients. METHODS AND RESULTS: During the observation period, 220 patients (11%) died (mean pacing interval, 50.5 +/- 7 months). Lethal cerebrovascular events in 66 of 220 patients (30%) and sudden death in 49 of 220 patients (23%) were the two most frequently reported modes of death. Nonsudden (first year, 20%; subsequent years, 6.9%; p less than 0.01) and sudden death mortality rate (4% versus 1.8%, p less than 0.05) were highest during the first year. Mortality was unrelated to the patient's activity status at the time of death. Sudden cardiac death occurred more often in male patients (increased risk, 1.7 versus female patients; p less than 0.001) and patients younger than 60 years of age (5.2 versus patients older than 60 years, p less than 0.001). Patients with severe bradycardia (sudden death rate, 28%), severe atrioventricular block (25%), or atrial fibrillation with low ventricular rate (25%) before pacemaker implantation were more likely to suffer from sudden cardiac death than patients with previous syncopal attacks (sudden death rate, 15%) or sick sinus syndrome (17%). The highest incidence of sudden death was observed in patients with bifascicular and trifascicular bundle branch block. In this group, 35% of patients died suddenly during the follow-up period compared with 18% of patients without bundle branch block. In a subsequent study in 90 consecutive patients with various types of bundle branch block, undersensing of up to 13% of ectopic ventricular beats occurred in patients with bifascicular block. Pacing-induced tachyarrhythmias and ventricular fibrillation were documented in 10% of undersensed ectopic ventricular beats as well as in the setting of atrial fibrillation associated with ventricular arrhythmias. CONCLUSIONS: Young age, male sex, and a severely diseased heart indicated by the presence of bifascicular and trifascicular bundle branch block are the strongest predictive clinical parameters for sudden cardiac death, especially in the first year after pacemaker implantation.

Aged↗
PubMed1992

Prevalence of circadian variations and spontaneous variability of cardiac disorders and ECG changes suggestive of myocardial ischemia in systemic arterial hypertension.

BACKGROUND: Systemic hypertension is a well-known risk factor for coronary artery disease and sudden cardiac death. Recent interest focused on the presence of malignant ventricular arrhythmias (VA) and myocardial ischemia in hypertensive patients and provided a potential link for fatal tachyarrhythmic events. METHODS AND RESULTS: We studied 150 untreated normokalemic hypertensive patients (56 +/- 9 years; 56 women and 94 men) without manifest coronary artery disease to determine prevalence, severity, and interaction of VA and significant ST segment changes induced by daily activities. One third of the patients were randomized to 4 weeks of placebo and restudied for spontaneous variability of the two parameters. All patients were included in a 3-year follow-up study. VA were observed in 129 of 150 hypertensive patients (86%) and peaked in the early morning and late afternoon. Twenty-two patients (15%) had ventricular pairs, and 20 patients (13%) had nonsustained ventricular tachycardia. Transient ST segment depression observed in 47 patients (33%; mean incidence, 2.7 +/- 0.8 episodes/24 hr) showed a characteristic circadian variation similar to VA and were asymptomatic in 93% of the episodes. At the time of transient ST segment depression, VA increased 4.6 times (p less than 0.01). After 4 weeks of placebo, marked variations in the incidence of VA (VA suppression rate -100%, or increase greater than 400%) were observed in 29% of the patients, and in 60% of all patients repetitive VA were present in only one of the two Holter recordings. Day-and-night variations of VA and transient ST segment changes were highly reproducible during the placebo period. After 3 years of follow-up, eight of 146 patients (5%) had suffered myocardial infarction, and five patients had died from cardiac events (three patients died from sudden cardiac death). Logistic regression analysis revealed left ventricular hypertrophy (relative risk, 6.1; p less than 0.01) and transient ST segment abnormalities during daily activities (relative risk, 4.4; p less than 0.05) to be of independent prognostic significance to predict cardiac events during follow-up instead of repetitive VA (relative risk, 1.3; NS). CONCLUSIONS: VA associated with a high spontaneous variability and predominantly asymptomatic transient ST segment changes are common in hypertensives; the interaction of both risk factors may provide an important link for fatal VA. Antiarrhythmic therapy is not to be recommended in the majority of patients. Presence of left ventricular hypertrophy and transient ST segment changes were the most powerful predictors of cardiac events during the follow-up.

Adult↗
PubMed1992

Efficacy of intravenously administered amiodarone for short-term control of serious arrhythmias.

Intravenously administered amiodarone exerts substantial antiarrhythmic activity that is based on several different electrophysiologic mechanisms. Of these, the most important consists of an antitachycardic effect together with a significant prolongation of repolarization. The acute intravenous administration of amiodarone has been found to be effective in supraventricular and ventricular tachyarrhythmias resistant to conventional antiarrhythmic agents. Because amiodarone is free of detrimental hemodynamic effects in the majority of patients, intravenous administration of this compound seems to be particularly suitable in patients with serious arrhythmias in the setting of compromised left ventricular function.

Action Potentials↗
PubMed1992

Exercise-induced symptomatic and asymptomatic myocardial ischemia in patients with severe coronary artery disease: focus on the efficacy and safety of gallopamil.

Symptomatic and asymptomatic episodes of transient myocardial ischemia are well-known risk factors in patients with coronary artery disease. In a single-blind, randomized, and placebo-controlled study, the efficacy and safety of gallopamil was studied during a 1-week treatment period in 25 patients with high-grade coronary artery stenosis and frequent, exercise-induced episodes of myocardial ischemia. Eighteen patients were men, and seven patients were women; the mean age +/- SD was 59 +/- 7 years. After a 1-week run-in period (days 1-7), all patients were treated with gallopamil 50 mg t.i.d. (days 8-14) and placebo t.i.d. (days 15-21) or vice versa. Twenty-four-hour Holter monitoring, exercise testing, and adverse effects were controlled at days 7, 14, and 21. During the run-in period, all patients suffered a mean of 5.9 +/- 2.9 episodes of transient myocardial ischemia, mean ischemic duration was 38 +/- 29 min/day. Gallopamil increased exercise tolerance from 7.9 to 9.8 min (+24%, p < 0.05) and resulted in reduction of the weekly usage of short-acting nitrates by 45% compared to placebo. During 24-h Holter monitoring, mean heart rate at the onset of ST-segment depression increased from 106 to 118 beats/min (p < 0.05). The frequency of daily ischemic episodes was reduced after gallopamil administration from 6.1 to 3.9 episodes/day (-37%, p < 0.05), the total ischemic burden decreased for symptomatic episodes by -54% (p < 0.05) and for asymptomatic episodes by 29% (p < 0.05). Gallopamil modified the circadian distribution of ischemic episodes by modifying the morning peak of transient myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Clinical evaluation of new anti-arrhythmia drugs after the CAST (Cardiac Arrhythmia Suppression Trial) study].

The results of the Cardiac Arrhythmia Suppression Trial (CAST) are of great importance for the development and clinical evaluation of new antiarrhythmic agents. Today, the development of a new antiarrhythmic drug is only justified, if the benefit risk ratio is superior compared to those agents already available in clinical practice. The primary criterion of therapeutic efficacy is the prevention of tachyarrhythmic sudden cardiac death and/or the prevention of sustained ventricular tachycardia.

Anti-Arrhythmia Agents↗
PubMed1992

[Risk stratification and long-term therapy with amiodarone in patients with idiopathic dilated cardiomyopathy].

Patients with cardiomyopathy are known to suffer from a high prevalence of tachyarrhythmic complications and sudden cardiac death. In a prospective study, 30 patients (25 men, 5 women, mean age: 52 +/- 12 years) with dilated cardiomyopathy underwent 48-h-Holter monitoring and programmed electrical stimulation and, independent from the results of the diagnostic work-up, were then randomized either to amiodarone or to a conventional or no antiarrhythmic therapy. At baseline, frequent ventricular arrhythmias (> 30 ventricular premature beats/h) were observed in 15/30 patients (50%), 13 patients (43%) had repetitive ventricular arrhythmias, additionally. Four patients suffered spontaneous sustained tachyarrhythmias. During programmed electrical stimulation, sustained monomorphic ventricular tachycardia was induced in 3/3 patients with and in 1/25 patients (4%) without a history of sustained tachycardia. Sustained monomorphic ventricular tachycardia was induced with one to two extrastimuli; three extrastimuli only increased the incidence of inducible ventricular fibrillation (8 patients, 28%). During a mean follow-up of 28 +/- 6 months 10/30 patients (33%) died for cardiac reasons (sudden cardiac death: 4/10 patients). Cardiac death was most likely in patients with a left-ventricular ejection fraction < 35% (5/18 patients, 28% versus 1/12 patients with ejection fraction > 35%, 8%) and further increased in the presence of reduced exercise tolerance and frequent and repetitive ventricular arrhythmias (4/7 patients, 57%). In the amiodarone group 4/15 patients died (27%, sudden cardiac death: one patient), while in patients not treated by amiodarone 8/15 patients died (54%; sudden cardiac death: three patients). Amiodarone therapy was well tolerated in all but one patient.

Adult↗
PubMed1992

[Sudden cardiac death: can individual risk be predicted?].

Only 30-40% of all victims of sudden cardiac death could so far be classified as risk patients during their lifetime. Risk factors for sudden death have little predictive value in an asymptomatic population: for example, the typical risk profile for the presence of coronary heart disease and changes in the surface-ECG at rest and especially in the surface-ECG under stress. Usually, the victims of sudden cardiac death among top performance athletes have been suffering from a heart disease of which they knew nothing beforehand: below 40 years of age, mostly from hypertrophic cardiomyopathy; beyond 40, predominantly from coronary heart disease. Among the heart diseases, sudden cardiac death is the cause of death most often in hypertrophic cardiomyopathy, in dilatative cardiomyopathy and in certain types of coronary heart disease. Notwithstanding the employment of fully update cardiological diagnostics the risk patients cannot be identified with reliable precision among those suffering from these diseases. It is only clinically manifest persistent ventricular tachycardia or successful reanimation in case of ventricular fibrillation that will definitely pinpoint the patient as being at risk of sudden cardiac death also in the future.

Cardiomyopathy, Dilated↗
PubMed1991

Time course and interrelation of reperfusion-induced ST changes and ventricular arrhythmias in acute myocardial infarction.

With the increasing use of thrombolytic therapy, the presence and time course of reperfusion-induced ventricular arrhythmias and ST-segment changes have become of particular interest. Technical improvements in bipolar Holter monitoring offer the opportunity to record both parameters continuously and simultaneously. Time course and interaction of both parameters in dependence on the onset of thrombolysis and time of reperfusion were investigated in 30 patients with acute myocardial infarction. Reperfusion was achieved in 20 patients after 49 +/- 23 minutes and in another 2 patients after 120 minutes (73%, group A). Vascular occlusion persisted in 8 patients for greater than 24 hours (group B). Sudden ST-segment changes (greater than 0.2 mV/15 min) in the bipolar leads indicated reperfusion in 7 of 22 patients (32%). Idioventricular rhythms, most frequent in reperfused patients (group A: 18 of 22 patients, mean 121 beats/hour), were unspecific reperfusion markers (group B: 5 of 8 patients, 1 beat/hour) unless frequent (p less than 0.05) or longer lasting, repetitive (p less than 0.01) episodes were considered. Premature ventricular beats and couplets (p less than 0.05) were also most frequent in group A (peak frequency 3 to 5 hours after thrombolysis). Ventricular tachycardia observed in 21 of 22 patients (95%) in group A and in 3 of 8 (38%) in group B (p less than 0.01) attained their peak frequency 7 to 9 hours after thrombolysis. They occurred most often in anterior myocardial infarction and were often preceded by frequent singular premature beats (r = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Tachycardic arrhythmias in athletes. Incidence, clinical relevance and prognostic significance].

Morphological and functional cardiac changes are found in all active athletes. Of particular interest would appear to be tachycardic arrhythmias, since they have been associated with cases of sudden death during sports activities. In comparison with patients with underlying cardiac disease, few data on the incidence and prognostic significance of tachycardic arrhythmias in athletes are available. The aim of the present study was to characterize and identify prognostically relevant tachycardic arrhythmias in this latter population.

Death, Sudden↗
PubMed1991

QT-interval prolonging drugs: mechanisms and clinical relevance of their arrhythmogenic hazards.

The antiarrhythmic principle of drug-induced QT-interval prolongation is well known. However, with the widespread use of the presently known and new Class III antiarrhythmic agents under investigation, and the growing number of agents not primarily designed as antiarrhythmic drugs that potentially cause QT prolongation, we have also become aware of the proarrhythmic hazards associated with many of these agents. The proarrhythmic risk differs markedly from one agent to another and interferes with many individual clinical variables (e.g., hypokalemia, sinus bradycardia). This paper summarizes the present data on the proarrhythmic risk of drug-induced QT prolongation, including the value and problems of the rate-corrected QT interval, the mechanisms involved in the genesis of proarrhythmia, and the clinical cofactors that facilitate the occurrence of proarrhythmic events. In addition, an extensive database provides information on the known proarrhythmic risk of all currently used QT-prolonging agents.

Animals↗
PubMed1991

Electrocardiographic and antiarrhythmic effects of intravenous amiodarone: results of a prospective, placebo-controlled study.

The antiarrhythmic efficacy of intravenously administered amiodarone was examined in a prospective, randomized, placebo-controlled study that involved 77 patients after coronary artery bypass surgery. Amiodarone was given after surgery in a loading bolus of 300 mg for 2 hours followed by 1200 mg every 24 hours for 2 days and 900 mg every 24 hours for the next 2 days. Amiodarone suppressed both supraventricular and ventricular arrhythmias within 12 hours after the start of therapy. Particularly, the incidence of atrial fibrillation (5% vs 21% in the control group; p less than 0.05) and of nonsustained ventricular tachycardia (3% vs 16%; p less than 0.05) was reduced by amiodarone. Heart rate was slowed (p less than 0.001) and repolarization--as judged by JTc interval--was prolonged compared with the control group (p less than 0.01). In two patients, amiodarone infusion was stopped because of excessive QTc prolongation. No detrimental hemodynamic effects of the drug were observed. Thus the intravenous administration of amiodarone appears to be suitable for patients in whom rapid suppression of symptomatic supraventricular and ventricular arrhythmias is warranted in the presence of left ventricular dysfunction.

Aged↗
PubMed1991

Efficacy and tolerance of the new class IB antiarrhythmic barucainide: an intravenous dose-finding study.

Barucainide is a new class IB antiarrhythmic agent that was studied for efficacy and safety after intravenous administration in patients with severe ventricular arrhythmias. All patients received 80 mg/hr barucainide intravenously for 7 hours or until ventricular arrhythmias were suppressed by greater than 90%. In responders a maintenance dose was given for 24 hours, aimed to achieve steady-state conditions. At baseline and during the treatment and washout periods 24-hour Holter recordings were performed. In addition, electrocardiogram, blood pressure, and plasma concentration of barucainide were measured. In 9 of 12 patients dose titration was effective (mean dose, 185 mg). In six of nine patients arrhythmia suppression persisted during maintenance therapy (mean dose, 18 mg/hr). Plasma concentrations correlated with given doses, rather than with antiarrhythmic efficacy. During the washout period, five patients required more than 12 hours for recurrence of arrhythmias. Treatment was stopped in one patient because of proarrhythmia; one patient had moderate heat sensations. Thus barucainide is a potent class IB agent, with a favorable side effect profile.

Anti-Arrhythmia Agents↗
PubMed1991

Can we predict sudden cardiac death?

Up to now only 30 to 40% of patients who die suddenly can be identified as likely candidates before the event. Risk factors in these asymptomatic subjects include a familial history of coronary artery disease, high blood cholesterol levels, hypertension, smoking and, more importantly, an abnormal ECG at rest or during exercise. The predictive value of these abnormalities is too low to justify more detailed clinical investigations in most of these asymptomatic subjects. Exceptions might be the group of patients with multiple risk factors and competitive sportsmen. Sudden cardiac death is a well known complication in patients with hypertrophic and dilated cardiomyopathy. Risk factors in hypertrophic cardiomyopathy include a familial history of this disease, syncope and increasing age. Furthermore, in the adult, the presence of nonsustained episodes of ventricular tachycardia during Holter monitoring seems to indicate an increased risk of sudden cardiac death. In idiopathic dilated cardiomyopathy, the presence of frequent episodes of ventricular pairs and/or episodes of ventricular tachycardia during Holter monitoring, together with a reduced left ventricular ejection fraction, characterises the patient at risk of sudden cardiac death. In patients with coronary artery disease, the patient at risk of sudden cardiac death can be identified by investigating the following: coronary anatomy; global and regional left ventricular function; the presence of ischaemia during rest and/or exercise; the presence of late potentials, by means of the signal-averaged ECG; the presence of spontaneous ventricular arrhythmias (especially sustained and nonsustained ventricular tachycardia); and the results of electrophysiological testing. On the basis of these investigations, 3 subgroups can be distinguished: patients at low risk, medium risk, and high risk of sudden cardiac death.

Death, Sudden↗