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Biomedical subjects

S H Hohnloser

Publications and source records attributed to S H Hohnloser.

At least 73 records · Page 4Linked to original sources
PubMed1998

Randomized comparison of slow pathway modification within the posteroseptal versus the midseptal area in patients with atrioventricular nodal reentrant tachycardia.

A total of 332 local electrogram recordings including 62 successful and 270 unsuccessful sites were analyzed. Univariate analysis revealed that there was a longer duration and more peaks of the atrial electrogram with a lower atrioventricular ratio and a higher incidence and shorter onset time of junctional ectopy during energy delivery at successful than at unsuccessful target sites.

Adult↗
PubMed1998

Assessment of QT dispersion for prediction of mortality or arrhythmic events after myocardial infarction: results of a prospective, long-term follow-up study.

BACKGROUND: Risk stratification by means of analysis of QT dispersion (QTD) in the 12-lead surface ECG is under intense investigation in various patient populations. The aim of the present prospective study was to evaluate the prognostic value of QTD and other ECG variables reflecting dispersion of ventricular repolarization in comparison with established risk stratifiers during long-term follow-up in a large cohort of post-myocardial infarction patients treated according to contemporary therapeutic guidelines. METHODS AND RESULTS: In 280 consecutive infarct survivors, the 12-lead ECG was optically scanned and digitized for analysis of QTD (QTmax-QTmin) and 25 other repolarization variables, including recently developed and validated parameters such as the T peak-to-T end interval and the area under the T wave. In addition, a variety of established risk stratifiers were assessed. After a mean follow-up period of 32+/-10 months, 30 patients reached one of the prospectively defined study end points (death, ventricular tachycardia, or resuscitated ventricular fibrillation). Comparisons between event and nonevent patients by means of Kaplan-Meier event probability analyses revealed that none of the ECG dispersion variables were of discriminative value. In contrast, variables such as left ventricular ejection fraction (P=0.007), mean 24-hour heart rate (P=0.022), or heart rate variability (P=0.007) proved to be potentially useful risk stratifiers in this patient population. On multivariate analysis, only LVEF, heart rate variability, and a history of thrombolysis were independent predictors of outcome. CONCLUSIONS: Determination of QTD from the surface ECG even when performed with the best available methodology failed to predict subsequent risk in this large series of infarct survivors.

Adult↗
PubMed1998

[Brief analysis of heart rate variability in for determining prognosis in the post-myocardial infarct period: methodologically reliable alternative to long-term ECG?].

Heart rate variability (HRV) has been established as an important risk parameter in patients surviving myocardial infarction. Recently, analysis of HRV-particularly of the standard deviation of NN intervals (SDNN)--from short term ECG recordings has been proposed as an alternative to that from 24 hour Holter monitorings. The present study is the first to compare SDNN from short term recordings to that from 24 hour recordings with respect to risk stratification after myocardial infarction. In 60 patients at the time of discharge from the hospital, SDNN from Holter monitoring averaged 93 +/- 30 ms compared to 39 +/- 18 determined from short term recordings. Patients with a prospectively defined clinical endpoint differed significantly from those with an uneventful course with respect to age, left ventricular ejection fraction, mean RR interval from Holter recording (753 +/- 153 vs 921 +/- 132 ms), mean RR from short term recording (783 +/- 153 vs 914 +/- 163 ms), and SDNN from the Hotler recording (71 +/- 27 vs 97 +/- 29 ms; p < 0.001). However, patients with and without a clinical event could not be separated by means of SDNN measured from short term ECG registrations (35 +/- 22 vs 41 +/- 19 ms; p = NS). Thus, SDNN measured from short term ECG recordings does not seem to be useful regarding risk stratification of patients after myocardial infarction. Analysis of HRV should be performed using 24 hour Holter monitoring, which provides more information and reflects circadian fluctuation in autonomic tone.

Adult↗
PubMed1998

Electrical storm in patients with transvenous implantable cardioverter-defibrillators: incidence, management and prognostic implications.

OBJECTIVES: The purpose of this study was to determine the precise incidence, therapeutic options and prognostic implications of electrical storm in patients with transvenous implantable cardioverter-defibrillator (ICD) systems. BACKGROUND: Approximately 50% to 70% of patients treated with an ICD receive appropriate device-based therapy within the first 2 years. Most arrhythmic events require only one appropriate ICD firing for termination. However, some patients receive multiple appropriate shocks during a short period of time, a condition referred to as "arrhythmic or electrical storm." METHODS: This prospectively designed observational study comprised 136 recipients of transvenous ICDs who were followed for 403+/-242 days. Electrical storm was defined as ventricular tachycardia or fibrillation resulting in device intervention > or = 3 times during a single 24-h period. RESULTS: During follow-up, 57/136 patients (42%) received appropriate ICD therapy. Electrical storm occurred in 14/136 patients (10%) at an average of 133+/-135 days after ICD implantation. The mean number of arrhythmic episodes constituting electrical storm was 17+/-17 (range: 3 to 50; median 8) per patient. In 12 patients, electrical storm required hospital admission. The arrhythmia cluster could be terminated by a combined therapy with beta-blockers and intravenous amiodarone whereas class I antiarrhythmic drugs were only occasionally successful. The cumulative probability of survival as estimated by the Kaplan-Meier method showed that patients with an episode of electrical storm did not have a worse outcome compared to those without such an event. CONCLUSIONS: Electrical storm represents a frequent event in patients treated with modern ICDs. It occurs most commonly late after ICD implantation and can be managed by combined therapy with beta-blockers and amiodarone. Electrical storm does not independently confer increased mortality.

Adult↗
PubMed1998

Intracardiac QRS electrogram width--an arrhythmia detection feature for implantable cardioverter defibrillators: exercise induced variation as a base for device programming.

Delivery of inappropriate therapy of implantable cardioverter defibrillators (ICD) due to inaccurate arrhythmia detection represents a major clinical problem. Different arrhythmia detection criteria such as the "stability" of the cycle length or the suddenness of "onset" of tachycardia have been implemented in ICD software to prevent inappropriate therapy. The new Medtronic model 7223Cx ICD offers an additional detection parameter (QRS width), which reflects changes in the duration of ventricular depolarization as a tool to distinguish supraventricular from ventricular tachycardias. Although this criterion can be programmed based on ECG parameters derived from resting ECGs, this may not be sufficient since QRS width is subject to considerable changes due to transient myocardial ischemia, changes in autonomic tone, or frequency dependent effects of antiarrhythmic drugs. The present study aimed to determine frequency dependent changes in QRS width in individual patients at rest and during symptom-limited exercise testing in 16 patients with documented ventricular tachycardia (N = 13) or ventricular fibrillation (N = 3). The optimal EGM slew threshold and the individual variation of QRS width were determined. Measurements obtained at the end of the implantation procedure were compared to those performed at hospital discharge. The majority of patients showed a wider variation in QRS duration as measured from 30 consecutive cycles during exercise as compared to rest. For example, the QRS range (i.e., the difference between the maximal and the minimal QRS width measured) averaged 7 +/- 3 ms at rest and increased to 11 +/- 3 ms during exercise (P = 0.004) with an increase of > or = 4 ms observed in 11 (69%) of 16 patients. In 13 (81%) of 16 patients a reprogramming of at least one QRS width parameter from its value at the time of implantation was necessary. Thus, the QRS width measured from the intracardiac EGM shows significant intraindividual variations in different physiological conditions. For optimal programming of the QRS width parameter, measurements obtained during exercise are important.

Defibrillators, Implantable↗
PubMed1998

Worldwide clinical experience with a down-sized active can implantable cardioverter defibrillator in 162 consecutive patients. Worldwide 7221 ICD Investigators.

Treatment with an ICD is the first-line treatment for survivors of sudden cardiac death. More recently, evidence accumulates that prophylactic ICD therapy may be beneficial for selected subgroups of patients after myocardial infarction. Particularly for future studies on the value of prophylactic ICD therapy, downsized devices are needed to allow easy pectoral implantation with a single lead configuration and featuring extended memory capabilities. Accordingly, this study assesses the clinical performance of a downsized fourth-generation ICD in 162 consecutive patients. All devices could be successfully implanted pectorally, in 96% with a single lead configuration with a low defibrillation threshold of 10.6 +/- 5.2 J. During a 3-month follow-up, 26% of the patients received ICD therapy. Twenty percent had appropriate therapy for ventricular fibrillation (n = 9) and VT (n = 23), which was effective in all cases. Of the 450 episodes of VT, 426 were terminated by antitachycardia pacing. Fourteen patients (9%) had inappropriate ICD therapy mainly due to atrial fibrillation or sinus tachycardia, which could be reliably diagnosed by the ICD stored intracardiac electrograms.

Adult↗
PubMed1998

T wave alternans as a predictor of recurrent ventricular tachyarrhythmias in ICD recipients: prospective comparison with conventional risk markers.

INTRODUCTION: The current standard for arrhythmic risk stratification is electrophysiologic (EP) testing, which, due to its invasive nature, is limited to patients already known to be at high risk. A number of noninvasive tests, such as determination of left ventricular ejection fraction (LVEF) or heart rate variability, have been evaluated as additional risk stratifiers. Microvolt T wave alternans (TWA) is a promising new risk marker. Prospective evaluation of noninvasive risk markers in low- or moderate-risk populations requires studies involving very large numbers of patients, and in such studies, documentation of the occurrence of ventricular tachyarrhythmias is difficult. In the present study, we identified a high-risk population, recipients of an implantable cardioverter defibrillator (ICD), and prospectively compared microvolt TWA with invasive EP testing and other risk markers with respect to their ability to predict recurrence of ventricular tachyarrhythmias as documented by ICD electrograms. METHODS AND RESULTS: Ninety-five patients with a history of ventricular tachyarrhythmias undergoing implantation of an ICD underwent EP testing, assessment of TWA, as well as determination of LVEF, baroreflex sensitivity, signal-averaged ECG, analysis of 24-hour Holter monitoring, and QT dispersion from the 12-lead surface ECG. The endpoint of the study was first appropriate ICD therapy for electrogram-documented ventricular fibrillation or tachycardia during follow-up. Kaplan-Meier survival analysis revealed that TWA (P < 0.006) and LVEF (P < 0.04) were the only significant univariate risk stratifiers. EP testing was not statistically significant (P < 0.2). Multivariate Cox regression analysis revealed that TWA was the only statistically significant independent risk factor. CONCLUSIONS: Measurement of microvolt TWA compared favorably with both invasive EP testing and other currently used noninvasive risk assessment methods in predicting recurrence of ventricular tachyarrhythmias in ICD recipients. This study suggests that TWA might also be a powerful tool for risk stratification in low- or moderate-risk patients, and needs to be prospectively evaluated in such populations.

Adult↗
PubMed1998

Atrial fibrillation--maintaining sinus rhythm versus ventricular rate control: the PIAF trial. Pharmacological Intervention in Atrial Fibrillation.

INTRODUCTION: In patients with persistent atrial fibrillation, therapy can be directed toward restoration of sinus rhythm or control of ventricular rate only. There are no prospective data in the literature comparing both treatment strategies. METHODS AND RESULTS: Patients with symptomatic persistent atrial fibrillation (duration > or = 7 and < or = 360 days) will be randomized to control of ventricular rate only or to conversion therapy. All patients will be followed for 12 months. Diltiazem is used as the primary therapy for rate control, whereas amiodarone will be administered for restoration and maintenance of sinus rhythm. The primary endpoint of the trial is the recurrence of symptomatic tachyarrhythmic episodes in patients randomized to rate control and recurrent atrial fibrillation in the alternative treatment arm. A number of secondary endpoints also will be investigated. The trial is expected to end its follow-up in the summer of 1998. CONCLUSION: PIAF (Pharmacological Intervention in Atrial Fibrillation) is one of several trials designed to evaluate the optimal treatment strategy in patients with persistent atrial fibrillation. The results hopefully will help to improve care of patients with this common rhythm disorder.

Animals↗
PubMed1997

Proarrhythmia with class III antiarrhythmic drugs: types, risks, and management.

The nature of the proarrhythmic reactions induced by antiarrhythmic drugs is linked to the electrophysiologic effects of these agents. Torsades de pointes is the classic form of proarrhythmia observed during therapy with any drug that prolongs repolarization, for example, the class III agents. Its precise electrophysiologic mechanism is not fully elucidated, although the arrhythmia is generally considered to be due either to early afterdepolarization in the context of prolonged cardiac repolarization or to an increase in spatial or temporal dispersion of repolarization. Among the class III drugs the proarrhythmic risk appears to be lowest for amiodarone, probably due to its complex electrophysiologic profile that may create significant myocardial electrical homogeneity. In the case of d,l-sotalol, the incidence of torsades de pointes increases with dose and the baseline values of the QT interval. Where d-sotalol and other pure class III agents might fall into the varying spectrum of proarrhythmic potential remains unclear. That d-sotalol has been found to increase mortality in postinfarction patients with ventricular dysfunction (the Survival With Oral d-Sotalol [SWORD] trial) is a matter of considerable concern. It raises the possibility that such a phenomenon may be a common property of most, if not all, pure class III compounds. Accordingly, care must be taken to minimize the likelihood of proarrhythmia; in particular, therapy with a class III agent should only be initiated in the presence of a defined indication established on the basis of clinical trials. When class III antiarrhythmic drug-induced proarrhythmia occurs, immediate cessation of therapy with the responsible agent and correction of predisposing factors, such as electrolyte disorders or bradycardia, is mandatory. Intravenous administration of high-dose magnesium sulfate has been demonstrated to be effective in terminating and preventing new episodes of torsades de pointes. Temporary pacing may be necessary.

Amiodarone↗
PubMed1997

[Drug therapy of ventricular arrhythmias].

In patients with no or only mild structural heart disease, spontaneous ventricular ectopy which causes symptoms is being treated with beta receptor antagonists, sotalol, or in rare cases with class I substances. For primary prevention of sudden death, for instance in survivors of myocardial infarction, beta receptor antagonists are the only substances for which benefit has been demonstrated in large scale trials. In contrast, class I agents are contraindicated for this purpose. In secondary prevention of sudden death in patients with a history of sustained ventricular tachycardia or ventricular fibrillation, treatment with sotalol or amiodarone can be considered. However, nonpharmacological therapy by means of implantable defibrillators is increasingly applied in this patient population.

Adrenergic beta-Antagonists↗
PubMed1997

[Combined therapy with transvenous cardioverter/defibrillator and anti-bradycardia pacemaker systems].

Implantable cardioverter/ defibrillators (ICD) represent in many patients with ventricular tachyarrhythmias the first line treatment. Up to 15% of the patients requiring an ICD need concomitant permanent cardiac pacing for bradyarrhythmias resulting in the need of simultaneous ICD- and antibradycardic pacemaker-therapy. We present four patients with successful implantation of a transvenous ICD-system (Medtronic Jewel 7220 and Micro Jewel 7221; electrode: Medtronic 6939), all of which had an antibradycardic pacemaker (2 unipolar, 2 bipolar) implanted prior to ICD-implantation. Meticulous intraoperative testing in order to avoid adverse interactions between the two systems has been carried out successfully in all cases. Possible adverse interactions comprise oversensing of pacemaker signals by the ICD with subsequent inadequate therapy, inhibition of defibrillation therapy during ventricular fibrillation caused by false detection of pacemaker spikes by the ICD as well as reprogramming of the pacemaker after shock delivery. A review of the published literature yielded 91 reported cases of combined ICD- and pacemaker-therapy. In 16% of the patients, one or more of the mentioned complications have been observed. Those occurred more frequently with unipolar than with bipolar pacemaker-systems. Thus, combined therapy with antibradycardic pacemaker and transvenous ICD-systems can be performed safely.

Aged↗
PubMed1997

Drug treatment of atrial fibrillation: what have we learned?

Pharmacologic treatment continues to be the mainstay of therapy in patients with atrial fibrillation (AF). Over the past few years, considerable progress has been made in establishing the role of antiarrhythmic drug therapy for restoration and subsequent maintenance of sinus rhythm as well as for the control of ventricular rate in permanent AF. For pharmacologic cardioversion, intravenous or oral administration of class IC drugs is associated with success rates of 60% to 80% depending mainly on the duration of the arrhythmia. In persistent AF of longer than 1 week's duration, electrical cardioversion is recommended because this method is more effective and safer than drug therapy. For maintenance of sinus rhythm following successful cardioversion, class I drugs continue to be used often. However, there is increasing awareness of their proarrhythmic risk, particularly in the case of quinidine. Sotalol, a class III agent with beta-receptor antagonism, is as effective as quinidine but better tolerated. In patients with so-called refractory AF, amiodarone has been proven to be effective in approximately 60% to 70% of treatment attempts. For control of ventricular rate, digoxin, beta-blockers, and calcium-channel antagonists are widely used. In these patients, chronic anticoagulation with warfarin aiming at international normalized ratios between 2.0 and 3.5 has been documented to significantly reduce thromboembolic risk.

Anti-Arrhythmia Agents↗
PubMed1997

Atrial fibrillation: maintaining stability of sinus rhythm or ventricular rate control? The need for prospective data: the PIAF trial.

Atrial fibrillation is one of the most commonly encountered clinical arrhythmias. Different treatment options for this rhythm disorder exist with the electrical and/or pharmacological cardioversion to sinus rhythm with subsequent antiarrhythmic drug therapy to prevent recurrences being one of the primary therapeutic goals. Another alternative, however, is represented by the control of the ventricular rate in patients with persistent atrial fibrillation. The question of which these two strategies should be preferred in the majority of patients with atrial fibrillation has not been studied in a prospective way. Given the background of conflicting data with respect to the prognostic impact of atrial fibrillation and of the increasing evidence concerning the risks of antiarrhythmic drug treatment in atrial fibrillation, a prospective multicenter trial has been initiated to compare these two therapeutic alternatives prospectively. Patients will be randomly assigned to cardioversion with subsequent antiarrhythmic drug therapy to prevent recurrent atrial fibrillation or to a therapy aiming exclusively at control of the ventricular rate during persistent atrial fibrillation. All patients will receive anticoagulation by means of warfarin (target INR 2.5-3.5) to prevent thromboembolic complications. The rationale and the design of the PIAF trial (Pharmacological intervention in Atrial Fibrillation) are discussed below. The pilot phase of this study has begun patient enrollment in the spring of 1995.

Adolescent↗
PubMed1997

Heart rate variability used as an arrhythmia risk stratifier after myocardial infarction.

Heart rate variability (HRV) is considered to represent a noninvasive tool to assess cardiac autonomic tone at the level of the sinus node. It has been shown to have predictive power for risk assessment in patients surviving acute myocardial infarction. For this purpose, HRV should be assessed from 24-hour Holter recordings obtained 7-10 days following the infarction. Although there is some recovery of HRV during the first 3 months after infarction, HRV remains reduced in postinfarction patients compared to values obtained in healthy individuals. Compared to assessment of left ventricular function as a risk marker, HRV is superior with respect to prediction of arrhythmic events and sudden death whereas both parameters yield comparative power for prediction of total cardiac mortality. Since the predictive power of HRV analysis alone is relatively low, the combined use of HRV measurements together with traditional risk markers (such as ventricular ectopic beats, signal-averaged ECG, or left ventricular function) results in improved risk prediction with positive predictive accuracy in the range of 30%-50%.

Arrhythmias, Cardiac↗