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.