Catheter ablation of ventricular arrhythmias: targets, tactics, and tools

Characteristics of ventricular tachycardia and long-term treatment outcome in patients with dilated cardiomyopathy complicated by lamin A/C gene mutations

BACKGROUND

Dilated cardiomyopathy caused by lamin A/C gene (LMNA) mutation is complicated with atrioventricular (AV) conduction disturbances, malignant ventricular arrhythmias, and progressive severe heart failure. Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) has been reported to be challenging due to the high recurrence rate in patients with LMNA-related cardiomyopathy. However, electrophysiological and histopathological characteristics of VT substrate remain to be fully elucidated.

METHODS AND RESULTS

We experienced 6 familial patients with LMNA-related cardiomyopathy in 3 pedigrees (6 males, 43.7±4.5 [SD] years). All patients had first VT attack at 50±6.6 [SD] years of age, and 4 underwent RFCA for incessant VT. Their electrocardiograms during VT showed similar QRS morphologies, characterized by an inferior axis, SR pattern in aVR, and QS pattern in aVL, suggesting the origin of the basal anterior ventricle. Indeed, the VTs had multiple exits around the basal anterior ventricular septum in all RFCA cases. Although we performed multiple RFCA procedures including epicardial ablation and surgical cryoablation, all cases experienced VT recurrences in 4.5±6.4 [SD] months after last procedure. All patients developed end-stage heart failure with frequent VT events, and died at 59.5±3.6 years of age (severe heart failure in 5 and lung disease in 1). In three autopsy cases with RFCA, fibrofatty degeneration was noted in the AV node. In addition, in the deep basal ventricular septum, inhomogenous fibrotic degenerated tissue was noted beyond the reach of RF lesions.

CONCLUSIONS

These results demonstrate that patients with LMNA-related cardiomyopathy are characterized by VTs refractory to RFCA probably because of the deep intramural focus at the basal ventricular septum, resulting in poor prognosis with progressive severe heart failure despite all available optimized therapies. Thus, we should consider heart transplantation in their early 50s when several VT events begin to occur.

Renal sympathetic denervation for treatment of ventricular arrhythmias: a review on current experimental and clinical findings

Ventricular arrhythmias (VAs) remain the major cause of mortality and sudden cardiac death (SCD) in almost all forms of heart disease. Despite so many therapeutic advances, such as pharmacological therapies, catheter ablation, and arrhythmia surgery, management of VAs remains a great challenge for cardiologists. Evidence from histological studies and from direct nerve activity recordings have suggested that increased sympathetic nerve density and activity contribute to the generation of VAs and SCD. It is well known that renal sympathetic nerve (RSN), either afferent component or efferent component, plays an important role in modulation of central sympathetic activity. We have recently shown that RSN activation by electrical stimulation significantly increases cardiac and systemic sympathetic activity and promotes the incidence of acute ischemia-induced VAs, suggesting RSN has a role in the development of VAs. Initial experience of RSN denervation (RDN) in patients with resistant hypertension showed that this novel and minimally invasive device-based approach significantly reduced not only kidney but also whole-body norepinephrine spillover. In addition, experimental studies find that left stellate ganglion nerve activity is significantly decreased after RDN. Based on these observations, it is reasonable to conclude that RDN may be an effective therapy for the management of VAs. Indeed, RDN has provided a protection against VAs in both animal models and patients. In this article, we review the role of the RSN in the generation of VAs and SCD and the role of RDN as a potential treatment strategy for VAs and SCD.