[Treatment of ventricular arrhythmias]

The term ventricular arrhythmia denotes various disorder in the cardiac rhythm--from isolated monomorphic ventricular extrasystoles to ventricular flutter and fibrillation. The choice of therapy of ventricular arrhythmias is primarily based on prognostic aspects. Ventricular tachycardias represent the main cause of sudden cardiac death, which is responsible for more than 60% of all deaths for cardial causes. In the industrially advanced countries the ventricular tachyarrhythmias represent more than 90% of cases based on coronary disease. The prevention of sudden death is directed particularly to prevention and therapy of ischaemic heart disease. The prognostic classification divides ventricular tachycardias into benign, potentially malignant and malignant ones, respectively. The benign arrhythmias do not require therapy. In the malignant (i.e. potentially lethal) ventricular tachyarrhythmias the implantation of cardioverter-defibrillator represents the most efficient treatment. In the largest group of patients with potentially malignant ventricular arrhythmias the present risk-oriented stratification enables a partial identification of persons with markedly increased risk of sudden death. They may be considered for preventive implantation of cardioverter-defibrillator. In some patients the therapeutic effect is reached by application of various therapeutic methods including a combination of pharmacological and non-pharmacological therapy, which also includes catheterization or surgical ablation of the arrhythmogenic substrate. A corresponding attention should be devoted to the basal cardial disease.

Coincidence of idiopathic ventricular outflow tract tachycardia and atrioventricular nodal reentrant tachycardia

BACKGROUND

Tachycardia-induced tachycardia appears to be a relatively rare condition. In such cases an important question arises whether catheter ablation of one arrhythmia may prevent the occurrence of another. This paper reviews single-centre experience with coincident idiopathic outflow tract ventricular tachycardia (VT) and atrioventricular (AV) nodal reentry tachycardia (AVNRT), and strategy of treatment.

METHODS AND RESULTS

Seven of 46 patients (15%) with clinically documented idiopathic outflow tract VT were found to have reproducibly inducible AVNRT at the time of an electrophysiological study. There were two men and five women (mean age 35+/-9 years, range 20-44) without structural heart disease. During the study, AVNRT spontaneously triggered VT in three cases. Radiofrequency catheter ablation of the slow pathway did not suppress subsequent inducibility of VT in any of them. Successful catheter ablation of VT did not prevent clinical recurrence of AVNRT in one patient, and led to transition of VT into typical AVNRT in another.

CONCLUSION

Coincidence of idiopathic outflow tract VT and AVNRT was found in 15% of cases of clinically documented idiopathic VT. Catheter ablation of one arrhythmia substrate did not prevent inducibility or clinical recurrence of the other. These data support the strategy of performing catheter ablation of both arrhythmia substrates during one session.

Radiofrequency catheter ablation of postinfarction ventricular tachycardia from the proximal coronary sinus

Optimum strategy for radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) after inferior wall myocardial infarction (MI) that originates from the posteroseptal process of the left ventricle is not known. We describe a case report of a 57-year-old man who developed recurrent post-MI VT with ECG morphology consistent with this type of VT (i.e., left bundle branch block pattern with predominant R waves from V2 to V6 and left-axis deviation). Endocardial mapping and entrainment during VT demonstrated a critical isthmus of the reentrant circuit in the proximal coronary sinus. RF application terminated VT and rendered it noninducible.

Recurrent pericardial chest pain: a case of late right ventricular perforation after implantation of a transvenous active-fixation ICD lead

A 36-year-old woman with a history of recurrent syncopal episodes presumably due to ventricular tachyarrhythmia in mitral valve prolapse underwent implantation of a transvenous ICD system. During a 23-month follow-up, she developed recurrent pericardial chest pain with pericardial friction rub. The first episode of chest pain occurred without any detectable change in pacing or sensing parameters. The second episode was associated with an increase in pacing threshold and drop in intracardiac signal amplitude. Right ventricular perforation was suspected fluoroscopically and confirmed by right ventriculography. This case report emphasizes the key steps in the diagnosis of this rare complication of an ICD implantation.

[Surgical therapy of serious heart rhythm disorders]

The author summarizes his experience with operations in 40 patients. Twenty-one were operated on account of W-P-W syndrome, 9 on account of ventricular tachycardia due to IHD and in 10 patients an automatic defibrillator was implanted. None of the patients died and the results of surgery are satisfactory.

[Tiracizine in the treatment of ventricular arrhythmia (preliminary study)]

Tiracizine a new antiarrhythmic drug class Ia was tested in a open crossover study in a group of 46 patients with more than 2500 ventricular extrasystoles per 24 hours or with ventricular arrhythmias III or a higher Lown class. The authors revealed a statistically significant drop of ventricular extrasystoles and a significant reduction of arrhythmias class IV of Lown's classification with a general shift of arrhythmias to lower classes. Improvement by at least one class occurred in 63%, deterioration without clinical impact in 11%. The drug does not have a clinical effect on haemodynamics. Side-effects of an anticholinergic type were recorded in 13% and a toxic allergic exanthema was observed in 6.5%. Tiracizine extends the spectrum of membrane antiarrhythmic drugs. Its effectiveness is similar as that of propafenon.

Changes in ventricular effective refractory periods after two extrastimuli and ventricular electrical instability

Using programmed stimulation with one and three extrastimuli delivered in the right ventricular apex, we compared the effective refractory period (ERP) during sinus rhythm (ERP-SR) and during the third extrastimulus (ERP-S3) in patients without ventricular tachycardias (control group, n = 87) and in patients with documented ventricular tachycardia (VT group, n = 76). The protocol was not completed to determine ERP-S3 in one patient in the control group and in 15 patients in the VT group. We observed a significantly greater change (i.e., shortening) in ERP after two extrastimuli in the VT group compared with patients without VT (delta ERP = 45 +/- 20 msec in the control group and 70 +/- 16 msec in the VT group, P < 0.001). This electrophysiological phenomenon, along with conduction delay, may play an important role in VT induction.

[How should ventricular arrhythmia be treated?]

Antiarrhythmic therapy of ventricular arrhythmias in patients after myocardial infarction, even if it reduces the incidence of arrhythmias, does not influence the mortality, as demonstrated in the American CAST study where the most effective antiarrhythmic drugs class Ic, encainide and flecainide, were used. As a result of proarrhythmogenic action therapy may even enhance the risk. The authors present a classification of ventricular arrhythmias and recommend therapeutic strategies. They draw attention to the fact that the proarrhythmogenic action may develop in the early as well as in the late stage of treatment. Beta-blockers still remain the only group of drugs which markedly reduce the incidence of sudden death in patients after myocardial infarctions.