Biomedical subjects
M Nürnberg
Publications and source records attributed to M Nürnberg.
[Implanted rhythm monitoring system--diagnostic and therapeutic options of anti-bradycardic pacemakers].
Monitoring of pacemaker patients is usually performed by 24 hour-long-term-ECG or event recorder. The newer pacemaker generation offers a variety of diagnostic features such as histograms, event counters of sensed or paced beats, trends of periodically measured lead impedance and amplitudes of sensed beats as well as automatic measurements of ventricular threshold. Predefined episodes of atrial and ventricular tachyarryhthmias can be documented as intracardiac electrogrammes and validated during pacemaker follow-up, thus leading to therapeutic consequences. Patient-triggered episodes can proove or exclude arrhythmogenic events. Special algorithms try to suppress the occurence of paroxysmal atrial fibrillation, newest pacemaker systems are even able to terminate atrial tachyarryhthmias by rapid atrial overdrive stimulation. Diagnostic and therapeutic options of modern antibradycardic pacemakers offer a permanent implanted rhythm-monitoring and try to reduce the incidence of atrial tachyarrhythmias.
[Sub-pectoral implantation of defibrillators: intraoperative data and long-term outcome].
UNLABELLED: The present study examined the perioperative mortality and morbidity and lead-related complications in patients who had a defibrillator with a transvenous lead system and subpectoral implantation of the generator. Fifty-four out of 57 consecutive patients (95%) received a transvenous lead system. One patient had an acceptable defibrillation threshold with an additional subcutaneous patch whereas no sufficient defibrillation threshold was found in another 2 patients. Two patients died due to congestive heart failure after implantation. Perioperative complications were observed in 4 patients (7%) including pericardial effusion, pocket hematoma, injury of the plexus brachialis and a pneumothorax. None of these complications required surgical intervention. Fifty-five patients were discharged from the hospital. During 27 +/- 10 months none of these patients died. Lead-related complications were observed in 3 patients (5.5%) including microdislocation in two and a outer conductor fracture in one of the lead. CONCLUSION: Technical advancement such as a non-thoracotomy lead system and smaller devices have made the onc-incision approach and subpectoral implantation of the ICD generator clinical routine. Nevertheless complications related to the lead system can occur. Therefore frequent controls of patients with ICD are necessary.
Present and future role of ambulatory Holter monitoring for arrhythmia risk stratification.
Risk stratification for arrhythmogenic events and sudden death in patients with organic heart disease, particularly those with coronary heart disease and a history of MI, continues to be one of the major tasks of clinical cardiologists, although advanced management strategies including thrombolysis, acute PTCA and surgical intervention dramatically reduced the percentage of sudden deaths following acute MIs, Noninvasive studies like resting and exercise ECG, echocardiography, signal averaging, 24-hour ECG, and radionuclide studies, as well as invasive techniques such as electrophysiologically programmed electrostimulation and coronary angiography, are being used routinely. Ambulatory Holter monitoring is an established noninvasive technique for risk stratification. There is evidence showing that its predictive potential for arrhythmogenic risks is enhanced, if more than one parameter is analyzed. Absence of ST segment changes and a normal HRV are the parameters signaling out low-risk patients. The use of additional parameters which escape electrocardiographic recording, like ventricular function and myocardial ischemia, improve the accuracy of predicting arrhythmogenic events. The most predictive combination of risk parameters is, however, still poorly understood. Future research should define normal ranges of parameters recordable by H-ECG, solve technical problems of recording data and analyzing them. In addition, the accuracy of measuring QT duration and documenting late potentials should be improved by more sophisticated methods. But it is unrealistic to expect that the QT interval will become amenable to automatic analysis in all patients. A fully automatic QT analysis without visually checking the measuring points at the tip and the end of the T wave for their consistency is hardly conceivable. The documentation of late potentials, in turn, is limited by artefacts caused by muscle contraction during physical activity. Clinical aspects, e.g., the predictability of arrhythmogenic events in patients with cardiomyopathies and valvular disease should be addressed. This will require studies combining the predictive potentials of rhythmologic and hemodynamic data.
Cardioverter discharges following sensing of electrical artifact due to fluid penetration in the connector port.
We report a unique case of fluid penetration, 3 months after implantation, in the connector port of an automatic implantable cardioverter defibrillator (ICD) with transvenous subcutaneous lead system. The patient had coronary artery disease and recurrent episodes of ventricular fibrillation, the fluid caused electrical signals interpreted as ventricular fibrillation by the device, which triggered shock delivery.
[Efficacy of the implantable cardioverter-defibrillator in patients on the waiting list for heart transplantation].
8 of 122 patients receiving an implantable cardioverter defibrillator (ICD) in our department since 1985 for the treatment of ventricular tachyarrhythmias were considered candidates for cardiac transplantation. In 6 of 8 patients, at least one successful ICD discharge (range 1-378 discharges) was documented in the follow up time until transplantation. These therapies included cardioversions/defibrillations as well as overdrive stimulation in sustained monomorphic ventricular tachycardia. 1 patient died shortly before receiving a compatible organ. The remaining 7 patients survived successful heart transplantation undertaken 7-34 months after implantation of the cardioverter defibrillator. Cardiac transplantation was not complicated in any of these patients by the previous ICD management. Our results show the high efficacy of ICD as "bridge to transplant" therapy unit cardiac transplantation.
[The value of tilt-table examination in diagnosis of syncope: studies of 24 patients].
Sudden hypotension, alone or combined with bradycardia is a major cause of syncope. 24 consecutive patients with a history of > 1 syncope of unknown aetiology were exposed to vagal provocation by the head-up tilt test. The clinical symptoms were reproduced in 11 patients under the given protocol, representing a sensitivity of 46%. The patients were followed up for 13.2 +/- 5.3 months. 7 of the 11 patients (64%) with a positive result on tilting versus 2 of the 13 patients (15%) with a negative result had a relapse of syncope. There was no statistical difference between the groups with regard to the number of syncopal episodes before patients were included in the study. Syncope in the head-up tilt test is, thus, a pointer towards identifying with a higher incidence of syncope on follow-up.
Hemodynamics during ventricular tachyarrhythmias.
The hemodynamic consequences of ventricular tachycardias are caused by cardiac and peripheral reactions. As a result, cardiac output and arterial pressure decrease. Even if the decrease is related to the tachycardia rate and left ventricular function, clinical symptoms do not in each case correlate with the degree of hemodynamic compromise. The explanation for this phenomenon is the different cardiac and peripheral reaction of patients to an immediate rise in heart rate. In this regard, it is questionable if pressure monitoring is superior to heart rate monitoring as a sensor for implantable antitachycardia devices.
Short-coupled variant of torsade de pointes. A new electrocardiographic entity in the spectrum of idiopathic ventricular tachyarrhythmias.
BACKGROUND: Torsade de pointes is characterized not only by its particular ECG pattern but by its context of congenital or acquired long QT syndrome and the long coupling interval of the initial premature beat. METHODS AND RESULTS: We observed 14 patients aged 34.6 +/- 10 years (mean +/- SD) with no structural heart disease who presented with syncope related to a typical ECG aspect of torsade de pointes. However, there was no evidence of long QT syndrome, and the torsade had the unusual particularity of an extremely short coupling interval of the first beat or of the isolated premature beats (245 +/- 28 milliseconds). In 10 cases they deteriorated into ventricular fibrillation. Four patients had a familial history of sudden death. Only 2 patients had a tachyarrhythmia inducible by programmed stimulation. At Holter recordings the heart rate variability was globally and significantly depressed, the vagal limb of the autonomic nervous system being predominantly affected. During a mean follow-up of 7 years there were 5 deaths (4 sudden). Nine patients are alive, 3 with implanted defibrillators and 6 treated with verapamil alone. Unlike the other types of antiarrhythmic agents including beta-blockers and amiodarone, verapamil is in our experience the only drug apparently active on the arrhythmias; however, it does not prevent sudden death. CONCLUSIONS: The short-coupled variant of torsade de pointes should be identified because of their ECG pattern and the risk of sudden death in young adults with no structural heart disease.
[Therapy monitoring in cardiac arrhythmias: guidelines for evaluation of anti-arrhythmia effects].
The incidence of avoidable or unavoidable, cardial and extracardial side effects is a risk in the drug treatment of supraventricular and ventricular tachyarrhythmias. Therefore the indication of antiarrhythmic drug therapy has to be considered critically. The patient has to be controlled close-meshed, especially at the beginning of the drug treatment. In patients with life threatening ventricular tachyarrhythmias, which can not be suppressed by drug therapy, nonpharmacological therapy--implantable cardioverter/defibrillator, catheterablation and heart-transplantation--has to be discussed.
[Complications in transvenous and transvenous-subcutaneous implantable defibrillator systems].
Due to technical improvement using the transvenous-subcutaneous approach for lead fixation for cardioverter-defibrillator implantation, the incidence of device implantation has extended enormously. While a significant lower perioperative mortality in transvenously implanted systems compared to epicardially fixed implantable cardioverter-defibrillator (ICD) has been proven, perioperative as well as complications during follow-up are not analyzed systematically. In 59 patients, in whom transvenous-subcutaneous ICDs had been implanted, 3 patients showed bleeding complications in the subcutaneous patch area, 1 patient showed a bleeding in the device pocket, and in 1 patient a seroma in the subcutaneous patch region was observed necessitating surgical revisions. During follow-up of 10 +/- 7 months, lead dislocations were observed in 6 patients, in another 6 patients patch crinkling was observed. There was 1 patient with a lead fracture as well as 1 patient with a bleeding in the subcutaneous patch region. Despite the high efficacy of this therapy used in patients with life-threatening ventricular arrhythmias, these potential complications have to be considered.
[Electrocardiography and electrophysiologic findings in patients with myotonic muscular dystrophy].
Myotonic dystrophy is associated with diffuse cardiac conduction disturbances. Seven consecutive patients, all asymptomatic with respect to cardiac abnormalities, were investigated by means of ECG, Holter monitoring, and invasive electrophysiologic studies (EPS). During Holter monitoring, no abnormalities were found in any patient, except for one patient who showed single monomorphic VEBs. During EPS three patients showed conduction disturbances in the AV-node (AVN) as well as in the His-Purkinje-system (HPS) in another three patients. Except for two patients ventricular vulnerability was normal during programmed ventricular stimulation. A considerable number of asymptomatic patients with myotonic dystrophy reveals AVN- and HPS-conduction disturbances as shown during EPS.
[Torsades de pointes with short coupling interval].
The authors describe a ventricular arrhythmia observed in 14 patients between 1972 and 1991, and 9 cases in the literature. The patients were hospitalised for investigations of syncope related to torsades de pointes. They were characterised by the very short coupling interval to the initiating extrasystole (average: 245 ms), by the young age of the patients (average: 34.6 years) and by the absence of overt cardiac disease. The resting electrocardiogrammes were normal, especially ventricular repolarisation. Some recordings showed isolated ventricular extrasystoles with short coupling intervals. Quite often, a family history of sudden death was obtained. These episodes of ventricular arrhythmia may degenerate to ventricular fibrillation. Pharmacological and electrophysiological investigations did not show any consistent characteristic electrophysiological behaviour. Investigations of autonomic nervous system function showed a decrease in global sinus rhythm variability and an increased sympathetic over parasympathetic activity. The clinical outcome of these patients is unpredictable with present methods. From a therapeutic point of view, Class I antiarrhythmics, betablockers and amiodarone were ineffective. Verapamil showed an electrocardiographic improvement by increasing the coupling interval of the extrasystoles and decreasing or even suppressing some repetitive forms, but without preventing recurrences. The indications for an implantable automatic defibrillator should be considered in this group of patients. These patients have clinical and electrocardiographic abnormalities which are sufficiently coherent for them to constitute a new pathological entity which the authors suggest calling "torsades de pointes with a short coupling interval".
[Implantation of defibrillators with transvenous-subcutaneous electrode systems].
In 23 patients an integrated pacemaker-defibrillator-system with transvenous-subcutaneous lead system was implanted. Two transvenous electrodes were positioned, one in the right ventricle for sensing, pacing and defibrillation and one in the superior vena cava for defibrillation alone. Another electrode was positioned subcutaneously near the ventricular apex for defibrillation. In 22 patients (96%) the lead system could be implanted without a major complication. The defibrillation threshold for ventricular fibrillation was 16 +/- 5 joules. During follow up of 6 +/- 4 months all spontaneous tachyarrhythmias were successfully terminated. There were three complications during follow up. In 2 patients the transvenous electrode dislocated and one patient showed a sensing malfunction. In conclusion the non-thoracotomy approach is effective, reduces the perioperative risk and represents therefore a great advantage compared to peri-/epicardial lead system.
[Serum magnesium, serum potassium and arrhythmia profile in patients with acute myocardial infarct].
In 176 patients with acute myocardial infarction (AMI) serum magnesium concentration (MGK) and serum potassium concentration (KK) were analysed during the first 48 hours after AMI. The patients rhythm was continuously recorded. In a subgroup of 70 patients a signal averaging-ECG was performed. 4.5% of the patients had a low, 55.7% a normal and 39.8% a high MGK. 14.8% of the patients had a low, 80.1% a normal and 5.1% a high KK. Ventricular arrhythmias > or = Lown IV b were found in 25% of the patients with low MGK, in 38.8% with normal and in 52.9% with high MGK. 50% of the patients with low, 62.2% with normal and 61.3% with high MGK had late potentials. There was no relation between hypomagnesemia and ventricular arrhythmias as between hypomagnesemia and late potentials. Thus, hypomagnesemia in AMI patients is rare and does not correlate with ventricular arrhythmia or delayed ventricular potentials.
[Non-drug therapy of ventricular tachycardia/ventricular fibrillation].
In the majority of patients with ventricular tachycardia/fibrillation drug treatment is not effective. The non-pharmacological treatment of this high-risk patients is of increasing importance. In Austria about 900 patients per year need non-pharmacological treatment of malignant ventricular arrhythmias. For this purpose 4 or 5 specialized centers would be necessary.
[Value of a provocation test with diprafenone in patients with bifascicular block].
The significance of provocative tests in patients with bifascicular block is not established. We studied 14 patients with bifascicular block, syncope and documented episodes of high degree AV-block. 1.5 mg/kg Diprafenon was given after a period of at last 12 hours 1:1 AV-conduction. Electrophysiologic evaluation was performed before and after diprafenon. AV-block III could be provoked in 1 of 14 patients with Diprafenon. Therefore a total AV block occurred in 7% of patients. The low sensitivity of provocative test with Diprafenon even in patients with documented high degree AV-block prevents its application in clinical practice.
[Silent ischemia in long-term ECG in the early post-infarct period].
101 consecutive patients (73 m, 29 f; 48 AMI, 53 IMI) under 70 years were assigned to 24 hour-Holter monitoring in the third week after first transmural infarction. ST-segment analysis could be performed in 88 patients (89%). 18 patients (20%) had episodes of ischemia which were silent in 95%. One third of these episodes occurred in the absence of physical exercise. Ischemic events displayed a circadian rhythm with a maximum between 6 and 12 a.m. There was no correlation between ischemia and the occurrence of ventricular arrhythmia. In addition, we show that visual control of automatic ST-segment analysis is a prerequisite for routine use in clinical practice.