Long-term outcome of verapamil-sensitive sustained left ventricular tachycardia in patients without structural heart disease

Mechanisms of idiopathic left ventricular tachycardia

Idiopathic left ventricular tachycardia (ILVT) differs from idiopathic right ventricular outflow tract (RVOT) tachycardia with respect to mechanism and pharmacologic sensitivity. ILVT can be categorized into three subgroups. The most prevalent form, verapamil-sensitive intrafascicular tachycardia, originates in the region of left posterior fascicle of the left bundle. This tachycardia is adenosine insensitive, demonstrates entrainment, and is thought to be due to reentry. The tachycardia is most often ablated in the region of the posteroinferior interventricular septum. A second type of ILVT is a form analogous to adenosine-sensitive RVOT tachycardia. This tachycardia appears to originate from deep within the interventricular septum and exits from the left side of the septum. This form of VT also responds to verapamil and is thought to be due to cAMP-mediated triggered activity. A third form of ILVT is propranolol sensitive. It is neither or initiated or terminated by programmed stimulation, does not terminate with verapamil, and is transiently suppressed by adenosine, responses consistent with an automatic mechanism. Recognition of the heterogeneity of ILVT and its unique characteristics should facilitate appropriate diagnosis and therapy in this group of patients.

Verapamil responsive incessant ventricular tachycardia resulting in severe ventricular dysfunction in a young child: successful management with oral verapamil

In young children with incessant ventricular tachycardia and severe ventricular dysfunction, the management of tachycardia with conventional antiarrhythmic drugs remains a major therapeutic challenge because most of these drugs can further depress myocardial function. We report a four year old boy with verapamil responsive incessant ventricular tachycardia and severe ventricular dysfunction in whom oral verapamil treatment eliminated both the arrhythmia and the picture of dilated cardiomyopathy. On oral verapamil, the patient remains asymptomatic without recurrence of the ventricular tachycardia over a follow up period of 10 months.

Experience with radiofrequency catheter ablation of fascicular tachycardia

OBJECTIVE

To report experience with radiofrequency catheter ablation of fascicular tachycardia including two cases of the rare type of this arrhythmia which arises from the anterior fascicle of the left bundle branch.

DESIGN

Review of results of radiofrequency ablation in nine consecutive patients presenting with fascicular tachycardia.

SETTING

Regional cardiac centre.

INTERVENTION

Percutaneous radiofrequency catheter ablation, performed between 1993 and 1996.

RESULTS

Radiofrequency ablation was successful in both patients with tachycardia arising from the anterior fascicle and in six of the seven patients with tachycardia arising from the anterior fascicle and in six of the seven patients with tachycardias arising from the posterior fascicle. Notable differences in the "right bundle branch block" configuration of lead V1 during tachycardia between patients were observed. One patient with incessant tachycardia had marked impairment of ventricular function which returned to normal after ablation.

CONCLUSIONS

Radiofrequency ablation is effective in both anterior and posterior fascicular tachycardias. The arrhythmia can cause reversible impairment of ventricular function.

Ventricular tachycardia: pathophysiology and radiofrequency catheter ablation

Limitations of pharmacological therapy for VT have led to great interest in alternative nonpharmacological therapies. The appeal of a curative therapy for VT initially led to the search for operative techniques to identify and destroy the underlying substrate, and more recently, has resulted in the development of catheter techniques to achieve the same goal in the electrophysiology laboratory. Investigations into the pathophysiology of VT have resulted in the recognition that this arrhythmia reflects a mechanistically and anatomically heterogeneous set of disorders. Recent growth in our understanding of these distinctions has both led to, and resulted from, simultaneous advances in catheter ablation techniques. The clinical electrophysiology laboratory has served as a testing ground for theories derived from in vitro and animal experiments while also providing its own set of human experimental data regarding the pathophysiology and treatment of VT. As a result of this process, several distinct forms of VT that are amenable to catheter ablation have been characterized. This article will summarize current knowledge of the pathophysiology of various VT subtypes and of techniques for catheter mapping and ablation.

Survivors of out-of-hospital cardiac arrest with apparently normal heart. Need for definition and standardized clinical evaluation. Consensus Statement of the Joint Steering Committees of the Unexplained Cardiac Arrest Registry of Europe and of the Idiopathic Ventricular Fibrillation Registry of the United States

BACKGROUND

A wide variety of structural abnormalities are associated with the vast majority of cardiac arrests. However, there is no evidence of structural heart disease in approximately 5% of victims of sudden death, indicating that cardiac arrest in the absence of organic heart disease is more common than previously recognized. The risk of recurrence and the acute and long-term response to therapy are important but unanswered questions. Data from the small series reported so far are of limited value because of the lack of uniform criteria to define and diagnose idiopathic ventricular fibrillation (IVF).

METHODS AND RESULTS

This report originates from a Consensus Conference convened by the Steering Committees of the European (UCARE) and North American (IVF-US) Registries on IVF under the auspices of the Working Group on Arrhythmias of the European Society of Cardiology. Its objective is to provide a unified definition of IVF and to outline the investigations necessary to make this diagnosis. Minimal diagnostic tests for the exclusion of an underlying structural heart disease include non-invasive (blood biochemistry, physical examination and clinical history, ECG, exercise stress test, 24-hour Holter recording, and echocardiogram) and invasive (coronary angiography, right and left ventricular cineangiography, and electrophysiological study) examinations. Programmed electrical stimulation, ventricular biopsy, and ergonovine test during coronary angiography are recommended but not mandatory.

CONCLUSIONS

It is recognized that despite careful evaluation, conditions such as focal cardiomyopathy, myocarditis, or fibrosis and transient electrolyte abnormalities may remain silent. Therefore, patients should undergo careful follow-up, with noninvasive tests repeated every year. The existence of a unified terminology will allow meaningful comparison of data collected by different investigators and will thus contribute to a better understanding of IVF.