[New ablation techniques in ventricular tachycardia]

Catheter ablation of ventricular tachycardia (VT) has proven to be effective in only a minority of VT patients. Therefore there is great interest in the development of new mapping and ablation techniques. New mapping procedures include multielectrode catheter mapping via the epicardial cardiac arteries and veins and the multielectrode basket catheter. Computerized non-contact mapping offers a three-dimensional approach in defining the activation sequence during VT. New ablative techniques are "cooled" radiofrequency energy application and microwave ablation which allow deeper and larger lesions. Already used in clinical practice are the application of laser energy and chemical ablation. New developments are ultrasound-, cryo- and thermal ablation. It can be suspected that some of these new achievements will lead to better results in VT ablation.

[Drug therapy of ventricular tachycardia]

For the emergency treatment of sustained, hemodynamically stable ventricular tachycardia, antiarrhythmic drugs are the therapy of choice. Mostly class I antiarrhythmic drugs, such as lidocaine or ajmaline, are preferred. In hemodynamically unstable ventricular tachycardia, electrical cardioversion should be applied, in case of recurrences, followed by pharmacological treatment with class I antiarrhythmic drugs or amiodarone. For the primary prevention of sudden cardiac death, beta-blockers and/or amiodarone are the only effective drugs. In the secondary prevention, only the implantable cardioverter/defibrillator has proved to improve the prognosis of the patients.

Coxsackievirus genome in myocardium of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy

Enteroviruses are known as major infectious agents for inflammatory heart diseases such as myocarditis and dilated cardiomyopathy (DCM). Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is characterized by replacement of right ventricular myocardium by fatty and fibrous tissue. In about 65% of patients inflammatory infiltrates suggest an inflammatory or infectious etiopathogenesis. To test this hypothesis, we investigated endomyocardial biopsies of patients with ARVC, with myocarditis or DCM, and from patients with non-inflammatory cardiac disorders for the presence of enteroviral genome. Enteroviral RNA with homology to coxsackieviruses type B was detected in 3 of 8 patients with ARVC (37.5%), in 7 of 23 patients with myocarditis or DCM (30.4%), but in none of 5 patient with non-infectious myocardial diseases (p < 0.05 compared to ARVC patients). These results support earlier suggestions that coxsackievirus infection of the myocardium is possibly related to the pathogenesis of ARVC.

Empirical versus tested antitachycardia pacing in implantable cardioverter defibrillators: a prospective study including 200 patients

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden cardiac death. The objective of this study was to evaluate whether testing of antitachycardia pacing (ATP) for induced ventricular tachycardias (VTs) at predischarge examination can predict ATP success during follow-up.

METHODS AND RESULTS

The study covers 200 consecutive patients who received ICD implants from June 1991 through December 1995. All underwent electrophysiological testing. In 54 patients (ATP tested, group T), ATP terminated induced VTs successfully. In 146 patients (empirically programmed ATP, group E), only ventricular fibrillation could be induced, including 18 with unsuccessful ATP attempts for induced VTs. Disregarding the results of ATP testing, the same ATP scheme was programmed in all patients: three attempts of autodecremental ramp with 81% of the VT cycle length, with 8 to 10 pulses. During a follow-up of 20.4 +/- 10 months, 95% of 3819 spontaneous VTs were successfully terminated with ATP in 42 patients of group T. In group E, 90% of 1346 spontaneous VTs in 81 patients were terminated with ATP. Acceleration after ATP occurred in 2% in group T versus 5% in group E. The success for all episodes in individual patients was > or =90% in >60% of the ATP tested and empirically programmed patients.

CONCLUSIONS

The results of this 200-patient prospective study comparing tested versus empirical ATP show high success (95% versus 90%) for VT termination, with low rates of acceleration. ATP is safe and very effective and should be programmed "on" in all patients regardless of the predischarge EP inducibility.

[Holter monitoring and programmed ventricular stimulation]

Long-term ECG recordings are the method of choice to evaluate quantity and quality of spontaneous rhythm disturbances. However, this method is limited by the variability of the arrhythmias. Invasive procedures such as programmed stimulation allow the provocation of tachyarrhythmias. Indications for both methods are diagnostic clarification of clinical symptoms, risk stratification with respect to arrhythmogenic sudden cardiac death as well as the control of antiarrhythmic therapy.Due to the high variability of spontaneous complex ventricular arrhythmias, Holter monitoring often fails to document the cause of severe symptoms such as syncope or sudden cardiac death. In these patients, invasive electrophysiological testing is required to provoke the arrhythmia.The prognostic significance of spontaneous ventricular arrhythmias recorded during ambulatory monitoring depends on the underlying cardiac disease. In patients with coronary artery disease and a history of myocardial infarction there is evidence that frequent single and/or complex ventricular extrasystoles indicate an increased risk of sudden cardiac death, especially in the presence of a reduced left ventricular function. In these patients, programmed ventricular stimulation can further characterize a highrisk group.For the management of antiarrhythmic therapy in symptomatic patients, under certain conditions both methods appear to be helpful. For the majority of these patients, however, the invasive electrophysiologic study should be preferred.Thus, long-term ECG recordings and programmed electrical stimulation are no competing, but complementary methods in clinical cardiology.

Inhibition of the voltage-dependent calcium current by extracellular ATP in hamster ventricular cardiomyocytes

The modulation of the high-voltage-activated calcium current (ICa) by external ATP was examined in single ventricular cardiomyocytes of the hamster using the whole-cell configuration of the patch-clamp technique. Extracellular application of ATP (0.1-100 microM) was found to inhibit ICa reversibly. The inhibition followed a slow time course (half time approximately 25 s) and was accompanied by very small changes of the holding current and no shift in the current-voltage relationship. With 100 microM ATP, peak ICa was reduced by approximately 30%. This response was not blocked by the P1 inhibitor 8-cyclopentyl-1,3-dipropylxanthine. The nonhydrolyzable ATP analogs adenosine 5'-O-(3-thiotriphosphate) and AMP-adenosine 5'-[beta,gamma-imido]triphosphate also reduced ICa. The ATP analog alpha,beta-methylene-ATP was about equipotent with ATP at 50 microM. Internal guanosine 5'-O-(3-thiotriphosphate) (200 microM) rendered the ATP-mediated inhibition of ICa poorly reversible, whereas internal guanosine 5'-O-(2-thiodiphosphate) (200-500 microM) had no effect. Holding the intracellular adenosine 3',5'-cyclic monophosphate concentration at a constant high level did not alter the ATP response. We conclude that external ATP inhibits ICa via a P2 purinergic receptor in hamster ventricular myocytes. Our results suggest the involvement of a G protein not coupled to adenylate cyclase. The inhibition of ICa by extracellular ATP might have pathophysiological relevance under conditions of myocardial injury.

Mipafox differential inhibition assay for heart muscle cholinesterases: substrate specificity and inhibition of three isoenzymes by physostigmine and quinidine

1. A differential inhibition assay was developed for the quantitative determination of cholinesterase isoenzymes acetylcholinesterase (AChE; EC 3.1.1.7), cholinesterase (BChE; EC 3.1.1.8), and atypical cholinesterase in small samples of left ventricular porcine heart muscle. 2. The assay is based on kinetic analysis of irreversible cholinesterase inhibition by the organophosphorus compound N,N'-di-isopropylphosphorodiamidic fluoride (mipafox). With acetylthiocholine (ASCh) as substrate (1.25 mM), hydrolytic activities (A) of cholinesterase isoenzymes were determined after preincubation (60 min, 25 degrees C) of heart muscle samples with either saline (total activity, A tau), 7 microM mipafox (AM1), or 0.8 mM mipafox (AM2): (BChE) = A tau-AM1, (AChE) = AM1-AM2, (Atypical ChE) = AM2. 3. The mipafox differential inhibition assay was used to determine the substrate hydrolysis patterns of myocardial cholinesterases with ASCh, acetyl-beta-methylthiocholine (A beta MSCh), propionylthiocholine (PSCh), and butyrylthiocholine (BSCh). The substrate specificities of myocardial AChE and BChE resemble those of erythrocyte AChE and serum BChE, respectively. Michaelis constants KM with ASCh were determined to be 0.15 mM for AChE and 1.4 mM for BChE. 4. Atypical cholinesterase, in respect to both substrate specificity and inhibition kinetics, differs from cholinesterase activities of vertebrate tissue and, up to now, could be identified exclusively in heart muscle. The enzyme's Michaelis constant with ASCh was determined to be 4.0 mM. 5. The reversible inhibitory effects of physostigmine (eserine) and quinidine on heart muscle cholinesterases were investigated using the differential inhibition assay. With all three isoenzymes, the inhibition kinetics of both substances were strictly competitive. The physostigmine inhibition of AChE was most pronounced (Ki = 0.22 microM). Quinidine most potently inhibited myocardial BChE (Ki = 35 microM).

Standardized assessment of psychological well-being and quality-of-life in patients with implanted defibrillators

The ICD has become a standard treatment for patients with malignant arrhythmias. Despite its benefits it may cause additional discomfort to the patients. Thus, quality-of-life needs to be assessed in these patients. Previous studies have used only small samples or unstandardized measures of quality-of-life that do not allow comparisons with other patient groups. The present study used standardized questionnaires for a cross-sectional assessment of psychological well-being and quality-of-life in ICD patients and to compare them to a similar group of coronary artery disease (CAD) patients without ICD. Overall, quality-of-life did not differ between both groups, ICD patients being less anxious than the CAD group. With increasing numbers of ICD shocks, however, the percentage of psychologically distressed ICD patients rose from 10% to > 50%. Psychologically distressed patients had significantly worse scores on most of the quality-of-life subscales, showed less treatment satisfaction, and more negative attitudes. It is concluded that ICD patients have an acceptable mean quality-of-life and low mean anxiety. However, a relevant subgroup of about 15%, especially patients with frequent shocks, experience psychological distress and reduced quality-of-life and should receive special care.

Indirect parasympathomimetic activity of the class III antiarrhythmic substance D/L-sotalol in vitro: reversible inhibition of cholinesterase isoenzymes from blood and the human central nervous system

Inhibitory effects of the class III antiarrhythmic compound D/L-sotalol on acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes of both erythrocytes and the human caudate nucleus and on serum cholinesterase (ChE; EC 3.1.1.8) were studied in vitro using a spectrophotometric kinetic assay with acetylthiocholine (ASCh) as substrate. Sotalol concentrations in the assays varied from 0.32 to 3.2 mM. All isoenzymes studied were inhibited by D/L-sotalol in a reversible and concentration-dependent manner. Double reciprocal plots of the reaction velocity against varying ASCh concentrations revealed that D/L-sotalol reduced substrate affinity (apparent Michaelis constant, KM, increased) of serum ChE, but did not change the enzyme's maximal rate of ASCh hydrolysis (Vmax). Thus, D/L-sotalol inhibition of serum ChE was of the competitive type (rate constant for reversible competitive inhibition: Ki = 0.51 mM). In contrast, D/L sotalol reduced the maximal reaction velocity of the AChE isoenzyme from the central nervous system (caudate nucleus), but had no influence on substrate affinity of the enzyme (KM with ASCh unchanged) indicating purely non-competitive inhibition kinetics (rate constant of reversible non-competitive inhibition: Ki = 0.44 mM). D/L-sotalol inhibition of erythrocyte AChE was of mixed competitive/non-competitive type (Ki = 0.31 mM, Ki = 0.49 mM). Non-competitive D/L-sotalol inhibition of caudate nucleus AChE and the non-competitive component of erythrocyte AChE inhibition cannot be overcome by increased concentrations of the cholinergic transmitter acetylcholine (ACh). Peak D/L-sotalol plasma levels as described in the literature for both humans (15 microM) and experimental animals (dogs: 18 microM; rats: 260 microM) as well as maximal myocardial concentrations of the substance (dogs: 46 microM; rats: 478 microM) are in the range of about 2% to 100% of the sotalol inhibition rate constants determined in the present paper for cholinesterase isoenzymes in vitro. Thus, D/L-sotalol inhibition of ACh hydrolysis in vivo may contribute to both the well known antiarrhythmic potential and proarrhythmic side effects of the compound.

Radiofrequency catheter ablation of right ventricular tachycardia late after repair of congenital heart defects

BACKGROUND

Ventricular arrhythmias after repair of congenital heart defects are a common finding and possibly contribute to sudden death in these patients. Optimal antiarrhythmic management has not yet been defined.

METHODS AND RESULTS

The study population consisted of 16 patients in whom ventricular arrhythmias occurred 11 to 42 years after complete surgical repair of congenital heart defects. Fifteen patients had a history of symptomatic sustained or nonsustained ventricular tachycardia, and 1 had frequent nonsustained ventricular tachycardia. The diagnostic mapping procedure to identify the origin of the arrhythmia included pace mapping during sinus rhythm, activation mapping, and pacing interventions during ventricular tachycardia. Catheter ablation was carried out by means of radiofrequency energy in the temperature-controlled mode. The follow-up period was 6 to 33 months (mean, 16 months). A right ventricular origin of the tachycardia in the surgically corrected area could be determined in all patients. Catheter ablation was carried out without complications. Immediate noninducibility was achieved in 15 of the 16 patients. One patient in whom the tachycardia was again inducible at repeat stimulation 1 week later was successfully treated with amiodarone. Eleven patients were taken off antiarrhythmic drugs. During follow-up, none of them had a recurrence of the tachycardia that had been ablated.

CONCLUSIONS

In patients with symptomatic or frequent ventricular tachycardia late after complete surgical repair of congenital heart defects, catheter ablation by means of radiofrequency energy is feasible and safe and thus might be taken into consideration for these patients. Short-term follow-up results are promising.

Enhanced detection criteria in implantable cardioverter-defibrillators to avoid inappropriate therapy

The aim of this prospective study was to evaluate the efficacy and safety of enhanced detection criteria, stability and sudden onset, for ventricular tachycardia (VT) in the therapy of implantable cardioverter-defibrillators (ICDs). These detection enhancements ensure a high specificity in detecting VT, thereby avoiding inappropriate therapy delivery due to supraventricular tachycardia. However, delayed sensing or even undersensing of VT may lead to a problematic, even fatal, outcome. In our study, the stability detection enhancement was programmed to discriminate atrial fibrillation (AF) in 84 of 124 patients with implanted ICDs and the sudden-onset detection enhancement in 47 of the 124 patients to discriminate sinus tachycardia. Using these enhancements in 124 patients with third-generation ICDs, 13 patients (11%) had inappropriate therapy during 20 months of follow-up. AF caused shock delivery in 6 patients (5%) and antitachycardia pacing in 4 patients, atrial flutter triggered shock therapy in 1 patient, and sinus tachycardia caused shock delivery in 2 patients. In 3 of the 13 patients inappropriate therapy recurred despite reprogramming the detection enhancements. The stability parameter of 241 spontaneous VT episodes as measured by the devices was 8 +/- 7 msec. Only 10 (4%) VTs had a stability parameter >25 msec. In 46 patients a combination of both detection enhancements, stability and/or sudden onset, were programmed. The use of detection enhancements proved safe and no patient had suffered negative side effects due to prolonged detection time or therapy delay. Inappropriate shock delivery due to AF, a major complication in ICD therapy, was reduced to 5% of patients. The use of the stability enhancement is recommended for patients with intermittent or chronic AF. Selected patients profit from programming both the stability and sudden onset criteria.

Implantable cardioverter defibrillator detection during radiofrequency catheter ablation of ventricular tachycardia

Right ventricular radiofrequency catheter ablation was performed in an ICD patient with frequent ventricular tachycardia without prior inactivation of the device. The registrations of intracardiac ECG and marker channel were excellent during energy delivery: the surface ECG was affected. The device did not show dysfunction during and after energy delivery.

Indirect parasympathomimetic activity of metoclopramide: reversible inhibition of cholinesterases from human central nervous system and blood

Inhibitory effects of the dopamine D2-receptor antagonistic benzamide compound metoclopramide (MCP) on acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes of both erythrocytes and human caudate nucleus and on human serum cholinesterase (ChE; EC 3.1.1.8) were studied in vitro using a spectrophotometric assay with acetylthiocholine (ASCh) as substrate. MCP concentrations in the assays varied from 0.30 microM to 0.15 mM. All isoenzymes studied were inhibited by metoclopramide in a concentration-dependent manner. MCP inhibition of AChE and ChE isoenzymes was not time-dependent and of the reversible type. Double reciprocal plots of the reaction velocity against varying ASCh concentrations revealed that, for AChE isoenzymes of erythrocytes and of the caudate nucleus, MCP reduced both maximal reaction velocity (Vmax) and substrate affinity (apparent Michaelis constant, KM, increased). Thus, MCP inhibition of both AChE isoenzymes was of mixed competitive/non-competitive type. MCP constants for reversible competitive (Ki) and non-competitive (Ki) inhibition could be determined for erythrocyte AChE (Ki = 10 microM; Ki = 70 microM) and caudate nucleus AChE (Ki = 9.3 microM; Ki = 82 microM). In contrast to MCP inhibition of AChE isoenzymes, the type of reversible MCP inhibition of human serum ChE depended on substrate concentration. If substrate concentration exceeded 0.2 mM, MCP inhibition was of mixed competitive/non-competitive type (Ki = 0.19 microM; Ki = 1.4 microM). MCP inhibition was of uncompetitive type, if substrate concentration was below 0.2 mM (Ki(u) = 1.0 microM). The mixed-type MCP inhibition of cholinesterase isoenzymes, because of its non-competitive component, can only partially be overcome by increased concentrations of the cholinergic transmitter acetylcholine (ACh). Since, with intravenous infusions, peak MCP plasma concentrations in humans reach 4 microM, MCP inhibition of ACh hydrolysis in vivo may contribute both to prokinetic and anti-emetic actions of the substance and to its extrapyramidal side effects.

Catheter ablation of incessant ventricular tachycardia: acute and long-term results

SUBJECTS

Seventeen patients with incessant ventricular tachycardia refractory to anti-arrhythmic therapy underwent catheter ablation between 1987 and 1993. Fifteen patients had coronary heart disease and two had dilated cardiomyopathy. The mean age of the patients was 65 +/- 8 and the mean left ventricular ejection fraction was 31 +/- 9%.

METHODS

Ablation sites were selected on the basis of endocardial activation mapping, concealed entrainment or bundle branch mapping. Catheter ablation was performed with direct current in nine patients and with radiofrequency energy in eight patients. Incessant ventricular tachycardia was terminated by catheter ablation in all 17 patients.

RESULTS

One patient died after the ablation procedure due to pericardial tamponade. During electrophysiological testing 5-14 days later, 7 of 16 patients (44%) had inducible sustained or non-sustained ventricular tachycardia. Five of them underwent implantation of an automatic cardioverter/defibrillator, and three of these experienced discharges of the device during a mean follow-up of 30 +/- 12 months. another patient underwent implantation of a cardioverter/defibrillator after spontaneous recurrence of ventricular tachycardia. Out of the nine patients without inducible ventricular tachycardia, one died as a result of sudden cardiac death, and another had spontaneous ventricular tachycardia. Thus, ventricular tachycardia recurred clinically in 6 of 16 patients (38%), in whom ventricular tachycardia with the same morphology as that of the ablated ventricular tachycardia could be determined only in one patient.

CONCLUSION

Catheter ablation is the method of choice for the emergency treatment of patients with incessant ventricular tachycardia. Due to the high risk of recurrence, additional anti-arrhythmic management, such as the implantation of a cardioverter/defibrillator, has to be considered.

[Transient pacemaker dysfunction and spontaneous arrhythmias in symptomatic and asymptomatic patients with ventricular demand pacemakers]

This prospective cross-sectional study include 100 consecutive patients (56 males, 44 females, 29 to 86 (mean = 67.5 +/- 12.2) years) with ventricular inhibited demand pacemakers 0.1 to 94.7 (mean 23.3 +/- 25.4) months after pacemaker implantation. Fifty-two patients were free of symptoms, whereas 48 patients were still complaining of syncope, dizziness, or palpitations. After history, physical examination, and 12-lead standard ECG all patients underwent 24-h Holter monitoring. A computer-aided analysis of spontaneous arrhythmias was done first. In a second run computed-aided analysis of transient pacemaker dysfunctions was performed with a specially designed pacemaker module. There were no significant differences between asymptomatic and symptomatic patients with regard to the incidence of transient pacemaker dysfunctions, with regard to defined types of pacemaker dysfunctions, spontaneous ventricular arrhythmias, and with regard to supraventricular tachycardias. A significant difference between asymptomatic and symptomatic patients was found, however, regarding the Lown classification of ventricular arrhythmias, because asymptomatic patients showed class 0 and I/II arrhythmias more frequently (p < 0.025). In the 100 patients a total of 6609 pacemaker dysfunctions were observed, 5104 failures to sense and 1505 inappropriate inhibitions. Most patients showed up to 240 pacemaker dysfunctions per 24 h. There were no failures to capture. Different types of pacemaker dysfunctions were found with different clinical implications. Due to the Holter findings in nine patients pacemakers were reprogrammed or replaced. After pacemaker implantation the number of patients with severe symptoms significantly decreased compared to the number of patients before pacemaker implantation. Nonetheless, there was a number of patients still complaining of symptoms after pacemaker implantation. In only a few patients did pacemaker implantation worsen symptoms . Our data show that with use of long-term ECG transient pacemaker dysfunctions and spontaneous arrhythmias are more frequent than patients' history and common standard techniques in the pacemaker clinic may suggest Holter monitoring, therefore, is a useful diagnostic tool, not only in symptomatic, but also in asymptomatic pacemaker patients. It allows to obtain a reliable survey of the real amount of transient pacemaker dysfunctions in the individual patient, which is the base for further therapeutic decisions.

Obstructive sleep apnoea and signal averaged electrocardiogram

Patients with obstructive sleep apnoea demonstrate an increased rate of ventricular arrhythmias. The present study was designed in order to investigate whether these arrhythmias may be related to myocardial injury, since myocardial injury of various aetiologies has been observed to change the signal averaged electrocardiogram (ECG). Signal averaged ECG was registered in 23 patients with obstructive sleep apnoea diagnosed by polysomnography (apnoea index 43 +/- 20 events.h-1, age 55 +/- 10 yrs). QRS duration, root mean square voltage of the last 40 ms of QRS, and low amplitude (< 40 mV) signal duration were determined from the vector magnitude of the QRS, high-pass filtered at 40 Hz. Patients with coronary heart disease or bundle branch block were excluded. No patient showed an abnormal signal averaged ECG. Mean duration of the filtered QRS complex was 96 +/- 9 ms, root mean square voltage 38 +/- 18 microV and low amplitude signal duration 26 +/- 8 ms. These results were not significantly different from 14 snoring subjects with an apnoea/hypopnoea index < 10. Four patients showed no ventricular arrhythmias and six patients had Lown III or IVa in the Holter ECG. Echocardiography revealed increased left atrial (43.7 +/- 4.1 mm) and interventricular septal diameters (11.3 +/- 1.4 mm). In conclusion, obstructive sleep apnoea does not generate a substrate for late potentials in the signal averaged ECG.

Obstructive sleep apnoea and signal averaged electrocardiogram

Patients with obstructive sleep apnoea demonstrate an increased rate of ventricular arrhythmias. The present study was designed in order to investigate whether these arrhythmias may be related to myocardial injury, since myocardial injury of various aetiologies has been observed to change the signal averaged electrocardiogram (ECG). Signal averaged ECG was registered in 23 patients with obstructive sleep apnoea diagnosed by polysomnography (apnoea index 43 +/- 20 events.h-1, age 55 +/- 10 yrs). QRS duration, root mean square voltage of the last 40 ms of QRS, and low amplitude (< 40 mV) signal duration were determined from the vector magnitude of the QRS, high-pass filtered at 40 Hz. Patients with coronary heart disease or bundle branch block were excluded. No patient showed an abnormal signal averaged ECG. Mean duration of the filtered QRS complex was 96 +/- 9 ms, root mean square voltage 38 +/- 18 microV and low amplitude signal duration 26 +/- 8 ms. These results were not significantly different from 14 snoring subjects with an apnoea/hypopnoea index < 10. Four patients showed no ventricular arrhythmias and six patients had Lown III or IVa in the Holter ECG. Echocardiography revealed increased left atrial (43.7 +/- 4.1 mm) and interventricular septal diameters (11.3 +/- 1.4 mm). In conclusion, obstructive sleep apnoea does not generate a substrate for late potentials in the signal averaged ECG.

[Bacterial endocarditis of the transvenous lead of an implantable cardioverter/defibrillator]

A 27-year-old patient carrying a transvenous ICD developed infective endocarditis more than 1 year after surgery. Staphylococcus aureus was isolated from blood cultures. A transesophageal echocardiogram revealed a mobile vegetation on a thrombus attached to the ICD lead in the right atrium. The ICD lead was removed by right anterolateral thoracotomy. This raises the issue of the risk of thrombus formation in patients with intravenous ICD leads and the associated susceptibility to infective endocarditis.

Catheter ablation of ventricular tachycardia in 136 patients with coronary artery disease: results and long-term follow-up

OBJECTIVES

This study attempted to determine the feasibility and long-term efficacy of catheter ablation by means of either radiofrequency or direct current energy in a selected group of patients with coronary artery disease.

BACKGROUND

Catheter ablation of ventricular tachycardia has proved to be highly effective in patients with idiopathic and bundle branch reentrant ventricular tachycardia. In patients with coronary artery disease and recurrent sustained ventricular tachycardia resistant to medical antiarrhythmic management, the value of catheter ablation has not yet been established.

METHODS

One hundred thirty-six patients with coronary artery disease and one configuration of monomorphic sustained ventricular tachycardia underwent radiofrequency (72 patients) or direct current catheter ablation (64 patients). The mapping procedure to localize an adequate site for ablation included pace mapping during sinus rhythm, endocardial activation mapping, identification of isolated mid-diastolic potentials and pacing interventions during ventricular tachycardia.

RESULTS

Primary success was achieved in 102 (75%) of 136 patients (74% of 72 undergoing radiofrequency and 77% of 64 with direct current ablation). Complications were noted in 12% of patients. During a mean (+/- SD) follow-up period of 24 +/- 13 months (range 3 to 68), ventricular tachycardia recurred in 16% of patients.

CONCLUSIONS

Catheter ablation of ventricular tachycardia in coronary artery disease is feasible in patients with one configuration of monomorphic sustained ventricular tachycardia. There is no significant difference with respect to the type of energy applied. The follow-up data show that in a selected group of patients with coronary artery disease, catheter ablation offers a therapy alternative.

[Symptomatic and asymptomatic myocardial ischemia before and after percutaneous transluminal coronary angioplasty]

The aim of the present study was to prove the effect of successful percutaneous transluminal coronary angioplasty (PTCA) on the occurrence of symptomatic and silent myocardial ischemia recorded during 24-h ECG, considering the number of diseased coronary arteries, a history of myocardial infarction, and the interval between myocardial infarction and PTCA. Before PTCA, 28 of 56 patients (50%) had ischemic ST-segment alterations, 3-8 days thereafter, there were only 13 patients (23%) with signs of myocardial ischemia (p < 0.01). The number of episodes of ischemia (IE) was reduced 44% (p < 0.05), their duration (ID) 51% (p < 0.01). In symptomatic patients, the decrease was 67% (p < 0.05) and 83% (p < 0.05), in patients with silent myocardial ischemia 20% (n.s.) and 29% (n.s.). Patients with one-vessel disease exhibited a 73% reduction of IE (p < 0.01) and a 85% reduction of ID (p < 0.01). In patients with two-vessel disease, the decrease was 47% (p < 0.05) and 26% (p < 0.05), whereas in those with three-vessel disease, there was no significant change. Patients without stenosis (< 50%) after PTCA had--irrespective of primary findings--a decrease of IE of 78% (p < 0.05) and of ID of 85% (p < 0.05), while patients with persisting coronary artery stenosis exhibited no significant decrease (20% and 35%, n.s.). In patients without history of myocardial infarction, the reduction of IE was 79% (p < 0.01) and that of ID 85% (p < 0.05); in patients with recent myocardial infarction (< 3 months) the decrease was 59% (p < 0.05) and 70% (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

[The reliability of computer-assisted long-term ECG analysis of pacemaker malfunction in patients with ventricular demand pacemakers]

The importance of the pacemaker follow-up clinic has markedly increased in the face of the currently available multiprogrammable pacemakers. In contrast to the common standard techniques in assessing pacemaker dysfunctions, Holter monitoring allows the detection of transient pace-maker dysfunctions during a long period of time. Especially computer-aided analysis provides a considerable progress, because different pacemaker dysfunctions can be detected during prolonged time periods, and--in contrast to visual analysis--a reliable survey of the real extent of transient pacemaker dysfunctions in the individual patient is assessed. The reliability of computer-aided analysis by a specially designed module was prospectively investigated in 100 consecutive patients with permanent ventricular inhibited demand pacemakers. It could be demonstrated that the positive predictive accuracy of this analysis was limited to 60.2% in detecting failures to sense and 63.2% in detecting inappropriate inhibitions, respectively. All detected failures to capture were false positive events. The positive predictive accuracy, therefore, was not calculated for this category of event. The overall positive predictive accuracy was 59.9%. In contrast, the sensitivity of computer-aided analysis was remarkably high. Possible causes of false positive and false negative findings are described. The reliability of pacemaker pulse detection was also investigated. Out of 100 analyzed Holter recordings five showed a temporary total loss of pacemaker pulses. Loss of single pacemaker pulses was found in 30 patients. False positive pacemaker pulses were seen in three patients. These results show that visual control and validation by an experienced physician are mandatory.(ABSTRACT TRUNCATED AT 250 WORDS)

[Relation of cardiologic findings and standardized psychological scales to clinical symptoms in 3,705 ergometrically studied patients]

3705 out of 4826 consecutive patients who were referred for exercise testing, completed a questionnaire immediately before the test. The questionnaire asked for sociodemographic data, cardiac history and symptoms, and additionally contained a German version of the Hospital Anxiety and Depression (HAD) scale. 22.5% of the patients had HAD scores > 10 indicating relevant anxiety or depression. High scores were associated with female sex, social problems, and normal cardiologic findings. After controlling for sex there was still a significantly higher portion of anxiety in men with angiographically normal vs. narrowed coronary arteries (20.6% vs. 8.3%; p = .0013). Cardiac symptoms as reported in the questionnaire showed slightly negative correlations (r = .00 to r = .15) with the number of narrowed coronary vessels, degree of left ventricular dysfunction and positive results of the exercise test. Multivariate analyses of variance revealed only minimal contributions of somatic findings to the explanation of symptom variance, while both HAD subscales accounted for the main portions of explained variance (p < .00005 for each symptom and overall symptom frequency). This could be explained by a selection process which lets numerous patients with heart-related symptoms of psychogenic origin seek a cardiologist's help, whereas many patients with coronary disease rather tend to deny their symptoms. Thus, even in a specialized cardiology service of a university hospital there are more patients with morbid levels of anxiety and depression than positive exercise tests. These patients are to be identified by means of an easily administered, objective, and well validated screening test. The HAD scale seems to meet these criteria and can be recommended for routine use.

Management of patients after catheter ablation of ventricular tachycardia

The management of patients after catheter ablation of ventricular tachycardia is not well defined. In this article we summarize recently published results and report our own experience. Factors influencing the clinical outcome of these patients and methods to identify patients with an increased risk of recurrence of ventricular tachycardia are discussed. Furthermore, a review is given on current concomitant therapeutic tools including antiarrhythmic drugs and the implantation of an automatic cardioverter defibrillator.

The effect of coronary bypass graft surgery for the prevention of sudden cardiac death: recurrent episodes after ICD implantation and review of literature

Sudden cardiac death (SCD) accounts for at least 50% of the mortality of patients with ischemic heart failure. Ventricular arrhythmias are responsible for most cases of sudden cardiac death. There is some evidence that coronary artery bypass graft (CABG) surgery may reduce the incidence of recurrent episodes of SCD by prevention of myocardial ischemia. To test the hypothesis that CABG surgery is effective in the prevention of SCD, we compared the recordings of implantable cardioverter defibrillators (ICD) in patients who underwent ICD implantation alone (n = 64) or ICD implantation and concomitant CABG surgery respectively (n = 11). All patients had experienced out of hospital cardiac arrest. ICD recordings were obtained every 3 months and the number of recurrent episodes of ventricular tachycardia (VT) for each time period was noted. Three months following ICD implantation patients in the surgically treated group had an average of one episode of VT per patient as compared to 2.7 episodes in the nonsurgical group. This difference was observed during the following months as well. However, at no time (up to 18 months of follow-up) this difference reached statistical significance. There were no deaths in the surgically treated group. Although we could not demonstrate a statistical significant difference between the two groups, there was a tendency in the surgically treated group to have less episodes of recurrent VT than in the medically treated group. We, therefore, conclude that survivors of SCD presenting with multivessel coronary artery disease (CAD) should undergo coronary artery bypass grafting to prevent myocardial ischemia as the triggering event for lethal ventricular arrhythmias.

[Quality assurance in cardiology: invasive electrophysiologic studies]

Quality assurance in invasive cardiac electrophysiology is of growing interest, also for cost-benefit-analysis. It can be achieved by following guidelines first published by the German Cardiac Society in 1985, which will soon be presented in revised form. Of major importance is proper education of the cardiologist who will be responsible for the indication, the enforcement, and the interpretation of the results. Furthermore, clear documentation is required in order to allow supervision, e.g., via spot checks by external experts.

[Ventricular macro-reentry tachycardia of the bundle branch type--indications for catheter ablation]

Out of 115 patients with recurrent sustained monomorphic ventricular tachycardia who underwent catheter ablation between August, 1987 and May, 1992, 7 were found to have bundle branch reentry. Bundle branch reentrant tachycardia was assumed if His potential or bundle branch potential preceded ventricular activation during tachycardia with identical H-H'- and V-V'-intervals. In 5 patients, catheter ablation of the right bundle branch and in 2 patients, ablation of the proximal left bundle branch were performed with direct current or radiofrequency energy. The procedure was successful in all 7 patients. During the follow-up of 15 +/- 12 months, 3 patients died due to cardiac failure. One patient had sustained ventricular tachycardia 12 months after catheter ablation which was not due to bundle branch reentry and was treated with an implantable cardioverter/defibrillator. Atrioventricular conduction delay in the surface electrogram and during electrophysiologic study may give a hint at bundle branch reentrant ventricular tachycardia since it was seen in 5 of our 7 patients. Catheter ablation of one bundle branch is an effective treatment which can prevent recurrence of this tachycardia.

[Ventricular late potentials in athletes]

Ventricular late potentials detected by signal averaging have a high predictive value for the origin of malignant ventricular tachyarrhythmias in patients with coronary artery disease. We examined 35 male sportsmen aged from 22 to 33 years. Clinical examination, ECG at rest, echocardiography and signal averaging were performed. In nine of the 35 sportsmen (26%) ventricular late potentials were detected. In a control group of 20 nonsportsmen none had late potentials. The nine sportsmen with late potentials all had electrocardiographical and echocardiographical signs of left-ventricular hypertrophy. Of the 26 sportsmen without ventricular late potentials five had left-ventricular hypertrophy. Ventricular late potentials are not rare in sportsmen. They seem always to appear together with left-ventricular hypertrophy.

[Subarachnoid hemorrhage with pulmonary edema and electrocardiographic changes. The differential diagnosis of myocardial infarct]

A 32-year-old man (weight 132 kg, height 190 cm) suddenly became unconscious and cyanosed with an unrecordable pulse and ventricular flutter on ECG. After resuscitation, the blood pressure was 200/100 mm Hg; the patient moved his arms and legs at times, but he did not regain consciousness. Focal neurological signs and meningism were not demonstrable. Subsequent ECGs showed a raised ST segment, followed later by terminal T wave inversion; marked pulmonary oedema was present clinically and radiologically. The creatine kinase activity was 344 U/l. As lateral myocardial infarction was suspected, the patient received heparin (1000-1700 IU/h) and nitroglycerin intravenously. Because the CK-MB isoenzyme failed to rise significantly and there was no reduction of R wave on the ECG, a CT scan of the brain was performed: this showed brain oedema as well as severe subarachnoid haemorrhage in the basal subarachnoid space, the posterior horn of the lateral ventricles and over the cerebral hemispheres. Despite implantation of an epidural pressure gauge, hyperventilation and administration of dexamethasone, osmotic diuretics and thiopental, the patient died 14 days after collapsing. At autopsy the heart showed no signs of myocardial infarction. The cause of the subarachnoid haemorrhage was a ruptured aneurysm of the anterior communicating artery.

Radiofrequency catheter ablation in recurrent ventricular tachycardia

Catheter ablation by radiofrequency energy was carried out in 10 patients with one type of recurrent monomorphic sustained ventricular tachycardia resistant to medical antiarrhythmic management. Electrophysiological studies before ablation included activation and pace-mapping. In all patients, the origin of the tachycardia was localized in the left ventricle: in the septum in six, at the posterolateral wall in three and anterobasal in one. The earliest onset of endocardial activation preceding the QRS complex during ventricular tachycardia ranged between -45 and -90 ms. Transcatheter ablation was performed with a bipolar or quadripolar catheter using a radiofrequency generator (HAT 100, Osypka). No complications occurred during the ablation procedure. Thereafter, in all patients, the clinical tachycardia was no longer inducible by programmed stimulation. During a follow-up period of 22 to 32 months including eight patients, the tachycardia recurred in two; one of these patients subsequently died suddenly. A third patient had one episode of a new type of sustained ventricular tachycardia some hours after catheter ablation. In the remaining patients, there was no recurrence of symptomatic tachycardia under maintenance of the antiarrhythmic management which, prior to ablation had been ineffective. Thus, our preliminary results suggest that radiofrequency catheter ablation might be beneficial for these high risk patients.

[Prevalence of late potentials in high frequency signal-averaged electrocardiography and arrhythmias in long-term ECG in healthy probands]

In a prospective study 79 symptom-free persons (41 females; 38 males) with an age range of 22-69 (mean 44) years were investigated by 48-h continuous ambulatory electrocardiography and by the signal-averaging ECG according to Simson's technique after having normal findings with echocardiography, standard ECG at rest and exercise stress test. Late potentials were defined according to Denes criteria (40 Hz highpass-filter); at least two out of the following three criteria had to be fulfilled for a correct positive finding: 1) QRS duration (QRSdur) greater than 120 ms; 2) root mean square of the last 40 ms (RMS 40) less than 20 microV; 3) mean duration of terminal low-amplitude signals (LAdur) greater than 39 ms. With long-term ECG 25% of the test subjects had no ventricular extrasystoles (VES), 28% had uniform VES, 33% multiform VES, 10% couplets, and 4% short runs of ventricular tachycardia during 48-hour recordings. Only 19% of them showed more than 48 VES/48 h. Individuals of advanced age demonstrated arrhythmias of higher Lown classes, as well as more frequent VES. By applying the signal-averaging technique 12.6% of the apparently healthy individuals showed late potentials, but none had LAdur greater than 45 ms. Individuals of higher age had not more late potentials than the younger ones. However, individuals with incomplete right bundle branch block pattern (n = 6) demonstrated with 50% significantly more often later potentials in comparison to 9.6% of those without this pattern (n = 73) (P less than 0.05). There was no correlation between late potentials and spontaneous arrhythmias, neither with regard to Lown classes, nor with regard to the frequency of VES. In conclusion, late potentials may occur in some individuals without apparent cardiovascular disease; they are unrelated to age as well as to spontaneous ventricular arrhythmias in normals.

[Effect of thrombolytic therapy in acute myocardial infarct on incidence of ventricular late potentials]

The aim of thrombolytic therapy for acute myocardial infarction is reperfusion of the infarction-related vessel. Ventricular late potentials detected by signal averaging have been demonstrated to be related to slow and inhomogeneous conduction within damaged cardiac tissue. In 75 patients with first myocardial infarction the effect of thrombolysis on ventricular late potentials was studied. Reperfusion of the infarction-related vessel could be demonstrated by coronary angiography in 53 (71%) patients. In 22 patients (29%) there was no reperfusion. In the 53 patients with successful thrombolysis the incidence of late potentials was significantly lower (9%) than in the 22 patients without reperfusion (50%). The lower incidence of late potentials may demonstrate improved ventricular electrical stability.

Prevalence of late ventricular potentials in hypertensive patients

Late ventricular potentials detected by signal averaging are used for predicting ventricular arrhythmias and sudden cardiac death in patients with coronary artery disease. We studied the prevalence of signal-averaged late ventricular potentials in 37 male patients (mean age of 56 years) with angiographically normal coronary arteries. Seventeen patients were hypertensive (group A) and 20 patients were normotensive (group B). In group A, 5 of 17 patients (29%) had late ventricular potentials. In group B, only 1 of 20 patients (5%) had late potentials (p less than 0.05). Late ventricular potentials detected by signal averaging are more common in hypertensive patients than in healthy controls. Whether late ventricular potentials can be used to predict malignant ventricular arrhythmias or sudden cardiac death in hypertensive patients will have to be investigated in further studies.

[Perforation of an automatic implantable cardioverter-defibrillator into the peritoneal cavity]

The automatic, implantable cardioverter-defibrillator is a new therapy for life-threatening ventricular tachyarrhythmias that are resistant to other therapy. Only a few complications, such as infections, lead defects, and interactions with pacemakers have been reported. We report on a patient whose AICD-generator perforated into the peritoneal cavity.

[Delayed-release verapamil hydrochloride in chronic atrial fibrillation. Reducing the heart rate]

In an open clinical trial, the therapeutic effect of sustained-release verapamil hydrochloride was investigated in 40 patients with chronic atrial fibrillation. As required, the daily dose was increased from 240 mg to 480 mg. A clinically relevant, statistically significant decrease in the heart rate was observed in almost all the patients. Since only four patients experienced mild side effects, with no major clinical significance, the preparation has a positive benefit/risk ratio for the indication investigated.