Heart rate dynamics at the onset of ventricular tachyarrhythmias as retrieved from implantable cardioverter-defibrillators in patients with coronary artery disease.

BACKGROUND: The recent availability of implantable cardioverter-defibrillators (ICDs) that record 1024 R-R intervals preceding a ventricular tachyarrhythmia (VTA) provides a unique opportunity to analyze heart rate variability (HRV) before the onset of VTA. METHODS AND RESULTS: Fifty-eight post-myocardial infarction patients with an implanted ICD for recurrent VTA provided 2 sets of 98 heart rate recordings in sinus rhythm: (1) before a VTA and (2) during control conditions. Three subgroups were considered according to the antiarrhythmic (AA) drug regimen. A state of sympathoexcitation was suggested by the significant reduction in HRV before VTA onset compared with control conditions. beta-Blockers and dl-sotalol enhanced HRV in control recordings; nevertheless, HRV declined before VTA independent of AA drugs. A gradual increase in heart rate and decrease in sinus arrhythmia at VTA onset were specific findings of patients who received dl-sotalol. CONCLUSIONS: The peculiar heart rate dynamics observed before VTA onset are suggestive of a state of sympathoexcitation that is independent of AA drugs.

[Sub-pectoral implantation of defibrillators: intraoperative data and long-term outcome]. / Subpektorale Implantation von Defibrillatoren: Intraoperative Daten und Langzeitbeobachtung.

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.

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.

The impact of implantable cardioverter-defibrillators on mortality among patients on the waiting list for heart transplantation.

Implantable cardioverter-defibrillators were investigated for their impact on mortality in 228 consecutive heart transplant candidates on the waiting list for transplantation (207 patients without and 21 with implantable cardioverter-defibrillator therapy). The mortality rate in 207 patients without implantable cardioverter-defibrillator therapy was 23.2% and in 21 patients with implantable cardioverter-defibrillator therapy was 4.7%. In a Cox proportional hazards model for all 228 study patients (mortality while on the waiting list: 21.5%; transplantation rate: 54.8%), the absence of an implantable cardioverter-defibrillator was only a marginally significant predictor of mortality (p = 0.079). However, the absence of an implantable cardioverter-defibrillator was a powerful predictor of mortality for a subgroup of 134 patients with high-grade ventricular arrhythmias on Holter electrocardiography (mortality while on the waiting list: 26.1%; transplantation rate: 54.5%; p = 0.022) and for a subgroup of 58 survivors of sudden cardiac death (mortality while on the waiting list: 22.4%; transplantation rate: 56.9%; p = 0.018). Implantable cardioverter-defibrillator therapy can be strongly recommended in transplant candidates with a history of sudden cardiac death. Recommendations for an expanded, prophylactic use of implantable cardioverter-defibrillator therapy in heart transplant candidates cannot be given.

[Efficacy of the implantable cardioverter-defibrillator in patients on the waiting list for heart transplantation]. / Effizienz des implantierbaren Cardioverter-Defibrillators bei Patienten auf der Warteliste zur Herztransplantation.

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.

[Strategies in management of heart transplantation candidates with tachycardic ventricular arrhythmia anamnesis]. / Strategien zum Management von Herztransplantationskandidaten mit der Anamnese tachykarder ventrikulärer Rhythmusstörungen.

We followed up 73 consecutive patients with a history of syncopal ventricular tachyarrhythmias on the waiting list for a heart transplant between 1st March 1992 and 15th September 1994 with the aim of evaluating the impact of implantable cardioverter defibrillator (ICD) on survival. On registration 60 patients were considered fit enough to be ambulant whilst awaiting transplantation. 30 were given ICD therapy (group 1) and 30 were not (group 2). 13 patients required inpatient supervision for ventricular arrhythmias whilst awaiting transplantation, but received no ICD therapy (group 3). The 13 in-patients were in a worse clinical state (NYHA) than the 30 out-patients not given ICD (p < 0.05). With respect to all other clinical and hemodynamic characteristics all groups were comparable. Waiting time for transplantation was also comparable in all groups (n.s., log-rank method). ICD therapy resulted in a significant improvement of survival in these high-risk patients prior to transplantation. Only 1 out of the 30 ICD patients (group 2) and 5 out of the 13 in-patients (group 3) (p < 0.05 log-rank method). During the waiting time group 3 patients were hospitalised longest (p < 0.05), but there was a clear trend that also ICD patients had to be hospitalised to an increased extent (n.s.). Cox multivariate regression analysis of this study population showed that the cardiac index (p = 0.001) and lack of ICD therapy (p = 0.035) were the only independent significant predictors of mortality on the waiting list. ICD therapy had no influence on mortality after transplantation (n.s. log-rank method).

[Complications in transvenous and transvenous-subcutaneous implantable defibrillator systems]. / Komplikationen bei transvenös bzw. transvenös-subkutan implantierbaren Defibrillatorsystemen.

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.

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.

[Therapy monitoring in cardiac arrhythmias: guidelines for evaluation of anti-arrhythmia effects]. / Therapiekontrolle bei Herzrhythmusstörungen: Richtlinien zur Prüfung antiarrhythmischer Wirkungen.

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.

[Electrocardiography and electrophysiologic findings in patients with myotonic muscular dystrophy]. / Elektrokardiographische und elektrophysiologische Befunde bei Patienten mit myotoner Muskeldystrophie.

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.

[Implantation of defibrillators with transvenous-subcutaneous electrode systems]. / Implantation von Defibrillatoren mit transvenös-subkutanem Elektrodensystem.

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.

[Value of a provocation test with diprafenone in patients with bifascicular block]. / Stellenwert eines Provokationstestes mit Diprafenon bei Patienten mit bifaszikulärem 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.

[Non-drug therapy of ventricular tachycardia/ventricular fibrillation]. / Nichtmedikamentöse Therapie von Kammertachykardie/Kammerflimmern.

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.

Acute and long-term efficacy of oral propafenone in patients with ventricular tachyarrhythmias.

The class Ic antiarrhythmic agent propafenone was studied by repeated electrophysiologic testing in 54 patients (43 male, aged 54 +/- 10 years, mean ejection fraction of 37.3 +/- 16.9%) with ventricular tachyarrhythmias. Forty patients (74%) had coronary artery disease. Programmed ventricular stimulation (S2, S2S3 during sinus rhythm and/or during S1S1 = 500, 430, 370, and 330 ms) off antiarrhythmic drugs induced sustained ventricular tachycardia, flutter, or fibrillation in all patients. After 450-900 mg of oral propafenone/day for 4-7 days, 51 patients were restudied. In the remaining three patients, spontaneous ventricular tachycardia occurred on drug therapy. Tachycardia induction was suppressed in 9 of 51 patients restudied (18%) and rendered more difficult to induce (basic stimulation drive greater than or equal to 40 beats/min higher than at control study) in another 7 patients (14%) (overall efficacy of 31%). The tachycardia rate decreased from 220 +/- 43 to 177 +/- 44 beats/min (p less than 0.01). The right ventricular effective refractory period increased from 232 +/- 22 to 252 +/- 22 ms (p less than 0.001). Responders to propafenone therapy had higher rates of inducible ventricular tachycardia at control (greater than 230 beats/min: 43%; less than or equal to 230 beats/min: 21%; p less than 0.05), higher ejection fractions, and lower left ventricular end-diastolic pressures than nonresponders. Eleven of the 16 patients showing a positive response to propafenone therapy in electrophysiologic testing were discharged on propafenone alone. During follow-up (17 +/- 12 months), nine patients remained free from ventricular tachycardia, one patient had a relapse, and one patient died of noncardiac death.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute and long-term efficacy of propafenone in patients with sustained ventricular tachyarrhythmias: assessment with programmed ventricular stimulation.

To determine the electrophysiological properties of oral propafenone, 50 patients (39 male and 11 female, aged 31 to 80 years) with sustained ventricular tachycardia or ventricular fibrillation underwent serial electrophysiological drug testing, using propafenone (750 to 900 mg daily) as the anti-arrhythmic regimen of first choice. During baseline study, all patients had inducible sustained ventricular tachyarrhythmias. After oral loading of propafenone, 37 patients (74%) remained inducible whereas 13 were rendered non-inducible. Among the still inducible patients, the mean VT rate decreased from 223 +/- 38 b.min-1 (baseline) to 172 +/- 32 b.min +/- 1 (P less than 0.001). Four patients showed an increase of VT rate during propafenone compared to the VT rate at control. Non-inducible patients were discharged on propafenone. During a mean follow-up period of 20 +/- 15 months, there were three non-fatal VT recurrences among the responders, two of them due to non-compliance. Thus, propafenone used as the anti-arrhythmic agent of first choice among patients undergoing serial electrophysiological drug testing for ventricular tachyarrhythmias proved effective in suppressing VT induction in 26%. With regard to arrhythmic events, these patients have a favourable outcome.

Acute myocardial infarction in juvenile patients with normal coronary arteries.

Three patients below 21 years of age presented with typical symptoms, electrocardiographic pattern, and levels of enzymes suggestive for acute myocardial infarction. Various risk factors for coronary artery disease were present in all three patients. Coronary angiography showed normal coronary arteries in all. Thus, acute myocardial infarction may be experienced even in very young patients. Clinical and angiographic findings are discussed on the basis of the existing reports in the literature.

Thermal catheter disruption during closed-chest radiofrequency ablation of the atrioventricular conduction system.

Radiofrequency ablation of the atrioventricular conduction system was attempted in a 63-year-old man with drug refractory atrial fibrillation. A total of 5 radiofrequency pulses (750 kHz, power setting: 25-50 W, pulse duration: 9-20 sec) were delivered in a unipolar fashion via the distal electrode of a 7 Fr bipolar electrode catheter without induction of permanent AV block. No direct measurements of current (I) and voltage (U) were made. During the fifth pulse catheter disruption occurred at the interface of the shaft and the proximal electrode. Inspection of the catheter shaft revealed carbonized insulation material indicating overheating of the catheter tip. Overheating was presumably due to an impedance rise with unrecognized clot formation on the distal electrode. This led to progressive melting of insulation material during repeated radiofrequency applications and short circuiting of current flow to the proximal ring electrode that resulted in catheter disruption. This case report is the first to describe a serious complication of radiofrequency ablation. The complication might have been prevented by measurements of U and I, reflecting changes in impedance or by measurements of catheter tip temperature (T). It is concluded that measurements of U, I, and/or T are necessary to control the coagulation process thereby reducing the risk of serious complications during transcatheter radiofrequency ablation.

Diagnostic value of electrocardiographic variables to predict the presence of ventricular late potentials.

To test the hypothesis that the presence of ventricular late potentials in the highly amplified, averaged and filtered surface electrocardiogram (ECG) can be predicted from the conventional surface ECG, 211 patients with and without previously documented sustained ventricular tachycardia outside the acute phase of myocardial infarction were studied. The presence of left ventricular akinesia or aneurysm was significantly correlated with the ECG score (based on Q wave duration, R wave duration and amplitude ratio). The mean ECG score in patients without ventricular tachycardia was 3.4 +/- 3.5 points compared with 5.5 +/- 3.9 points (p less than 0.001) in patients with ventricular tachycardia. The presence of late potentials was positively correlated with the ECG score in the whole cohort of patients. This was also the case in the subgroup of patients without a history of sustained ventricular tachycardia. In contrast, in patients with ventricular tachycardia, the presence of late potentials was independent of their ECG score. Using linear discriminant function analyses to predict the presence of late potentials, a history of ventricular tachycardia alone and the ECG score alone had a high predictive power (high standardized coefficients). If combinations of variables were analyzed including estimates of left ventricular function (presence of aneurysm or akinesia; ejection fraction), the ECG score and a history of ventricular tachycardia still ranked highest. The influence of ejection fraction if used in combination with other variables for the prediction of late potentials was relatively small (standardized coefficient of 0.4). In conclusion, the surface ECG can be used in patients previously free of sustained ventricular tachycardia to predict the presence of ventricular late potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of flecainide in pacing-induced sustained ventricular tachyarrhythmias: correlation to clinical parameters and tachycardia-characteristics.

Seventy-two patients with sustained ventricular tachycardia or syncope of unknown origin underwent electrophysiologic evaluation before and after therapy with flecainide (200-300 mg day-1). In all patients, sustained ventricular tachycardia or ventricular fibrillation was inducible during control electrophysiologic study. During flecainide therapy, sustained ventricular tachycardia (VT) was no longer inducible in 18 patients (25%) whereas in 54 patients, VT was still inducible. In five of the latter patients, VT became more difficult to induce (overall efficacy 32%). The rate of VT decreased from 214 +/- 49 beats min-1 during the control electrophysiologic study to 178 +/- 48 beats min-1 during flecainide (P less than 0.01). The ERP of the right ventricle increased from 251 +/- 27 ms during the control study to 267 +/- 34 ms on flecainide (P less than 0.01). Mean ejection fraction and mean LVEDP did not differ between responders and non-responders, yet the presence of a left ventricular aneurysm correlated with a lack of antiarrhythmic response to flecainide. VT rate as well as VT morphology during the control study discriminated between responders and non-responders; 11% of patients with VT-rate less than or equal to 230 beats min-1 responded to oral flecainide compared with 31% with a VT rate greater than 230 beats min-1 at control. 26% with induced monomorphic VT responded, compared with 100% with induced VF during the control study. 18 of 23 responders were discharged on flecainide. During a mean follow-up of 26 +/- 18 months, two patients experienced a recurrence of VT and in one patient, flecainide had to be discontinued due to side-effects.(ABSTRACT TRUNCATED AT 250 WORDS)