Radiofrequency catheter ablation of drug refractory symptomatic ventricular ectopy: short- and long-term results

Catheter ablation of ventricular ectopy with para-hisian origin: importance of mapping both sides of the interventricular septum and understanding when to stop ablating

Catheter ablation of para-Hisian premature ventricular contractions (PVCs) still represents a challenge and is a compromise between success and inadvertent AV block. We describe a possible strategy to address PVCs from this location with high-amplitude His-bundle potentials at the site of earliest activation.

Treatment Or Cure Of Right Ventricular Outflow Tract Tachycardia

Right ventricular outflow tract (RVOT) ventricular tachycardias (VT) occur in the absence of structural heart disease and are called idiopathic ventricular arrhythmias. These arrhythmias are thought to be produced by adenosine-sensitive, cyclic AMP mediated, triggered activity and are commonly observed in adolescents and young adults. In the ECG, they appear with a wide QRS complex, a left bundle branch block morphology and, usually, an inferior QRS axis. In the last few years, there has been an increasing number of reports suggesting the possibility of a curative treatment of RVOT VT by means of catheter ablation. This paper reviews the rate of cure of such arrhythmias by discussing the effects of catheter ablation on symptoms, arrhythmia detection, possibility of induction, and short- and long-term follow-up studies.

Chronic Hemodynamic Effects After Radiofrequency Catheter Ablation of Frequent Monomorphic Ventricular Premature Beats

INTRODUCTION

Radiofrequency catheter ablation (RFCA) of severely symptomatic monomorphic ventricular premature beats (VPBs) is reported to be a safe and effective treatment option. However, the chronic hemodynamic effects of these VPBs have not been precisely evaluated.

METHODS AND RESULTS

We sought to investigate chronic effects after decreasing the number of VPBs by RFCA. A total of 47 patients who had no underlying heart disease and frequent monomorphic VPBs, consisting of more than 10,000 beats per day (24,194 +/- 12,516 beats per day), were enrolled. Patients were treated with RFCA and followed up over 6 months as outpatients. Echocardiography and serum B-type natriuretic peptide (BNP) level were repeatedly checked before and after RFCA. In 38 patients, whose VPBs were dramatically decreased to less than 1,000 beats per day by successful RFCA, left ventricular (LV) end-diastolic dimension (LVEDd) and end-systolic dimension (LVESd) measured by echocardiography decreased significantly (LVEDd: 50 +/- 5 to 48 +/- 5 mm, P < 0.01; LVESd: 33 +/- 7 to 30 +/- 6 mm, P < 0.01) in association with improvement of BNP level (39.9 +/- 34.1 to 16.8 +/- 10.3 pg/mL, P = 0.0001). In nine patients, whose VPBs were treated unsuccessfully by RFCA or that recurred, LV dimensions and BNP level did not change during the follow-up period.

CONCLUSION

Significant improvement in LV dimensions and serum BNP level appeared to indicate that RFCA of VPBs ameliorated occult cardiac dysfunction induced by frequent VPBs.

Electrocardiographic Characteristics of Repetitive Monomorphic Right Ventricular Tachycardia Originating Near the His-Bundle

INTRODUCTION

Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His-bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His-bundle in comparison with right ventricular outflow tract (RVOT)-VT/VPCs.

METHODS AND RESULTS

Ninety RV-VT/VPC patients underwent catheter mapping and radiofrequency ablation. ECG variables were compared between VT/VPCs originating from the RVOT and near the His-bundle. Ten patients had foci near the His-bundle (HIS group), with the His-bundle local ventricular electrogram preceding the QRS onset by 15-35 msec (mean: 22 msec) and His-bundle pacing produced a nearly identical ECG to clinical VT/VPCs. The HIS group R wave amplitude in the inferior leads (lead III: 1.0 +/- 0.6 mV) was significantly lower than that of the RVOT group (1.7 +/- 0.4 mV, P < 0.05). An R wave in aVL was present in 6 of 10 HIS group patients, while almost all RVOT group patients had a QS pattern in aVL. Lead I in HIS group exhibited significantly taller R wave amplitudes than RVOT group. HIS group QRS duration in the inferior leads was shorter than that of the RVOT group. Eight of 10 HIS group patients exhibited a QS pattern in lead V1 compared to 14 of 81 RVOT group patients. HIS group had larger R wave amplitudes in leads V5 and V6 than RVOT group.

CONCLUSION

VT/VPCs originating near the His-bundle have distinctive ECG characteristics. Knowledge of the characteristic QRS morphology may facilitate catheter mapping and successful ablation.

Electrocardiographic and electrophysiologic characteristics of ventricular tachycardia originating within the pulmonary artery

OBJECTIVES

We investigated the electrocardiographic (ECG) and electrophysiologic characteristics of ventricular tachycardia (VT) originating within the pulmonary artery (PA).

BACKGROUND

Radiofrequency catheter ablation (RFCA) is routinely applied to the endocardial surface of the right ventricular outflow tract (RVOT) in patients with idiopathic VT of left bundle branch block morphology. It was recently reported that this arrhythmia may originate within the PA.

METHODS

Activation mapping and ECG analysis were performed in 24 patients whose VTs or ventricular premature contractions (VPCs) were successfully ablated within the PA (PA group) and in 48 patients whose VTs or VPCs were successfully ablated from the endocardial surface of the RVOT (RV-end-OT group).

RESULTS

R-wave amplitudes on inferior ECG leads, aVL/aVR ratio of Q-wave amplitude, and R/S ratio on lead V(2) were significantly larger in the PA group than in the RV-end-OT group. On intracardiac electrograms, atrial potentials were more frequently recorded in the PA group than in the RV-end-OT group (58% vs. 12%; p < 0.01). The amplitude of local ventricular potentials recorded during sinus rhythm within the PA was significantly lower than that recorded from the RV-end-OT (0.62 +/- 0.56 mV vs. 1.55 +/- 0.88 mV; p < 0.01).

CONCLUSIONS

Ventricular tachycardia originating within the PA has different electrocardiographic and electrophysiologic characteristics from that originating from the RV-end-OT. When mapping the RVOT area, the catheter may be located within the PA if a low-voltage atrial or local ventricular potential of <1-mV amplitude is recorded. Heightened attention must be paid if RFCA is required within the PA.

Prevalence and Electrocardiographic Characteristics of Idiopathic Ventricular Arrhythmia Originating in the Free Wall of the Right Ventricular Outflow Tract

BACKGROUND

The prevalence and ECG characteristics of idiopathic ventricular arrhythmia originating in the free wall of the right ventricular outflow tract (RVOT) require further clarification, which was the aim of the present study of 110 patients with idiopathic ventricular tachycardia (n=34) or premature ventricular contraction (n=76; OT-VT/PVC) who underwent successful catheter ablation at the RVOT.

METHODS AND RESULTS

Ten OT-VT/PVCs (9%) were ablated successfully at the free wall (FW-VT/PVC); the remaining 100 (91%) were ablated at the RVOT septum (Sep-VT/PVC). R wave amplitudes in the inferior leads were significantly smaller in FW-VT/PVC than in Sep-VT/PVC (p<0.01). An RR' pattern in the inferior leads was observed significantly more often in FW-VT/PVC than in Sep-VT/PVC (p<0.001). QS-wave amplitude in each of leads V(1) to V(3) was significantly deeper in FW-VT/PVC than in Sep-VT/PVC (p<0.001). ECG criteria requiring an RR' pattern in all inferior leads as well as an S-wave amplitude of at least 3.0 mV in lead V(2) differentiated FW-VT/PVC from Sep-VT/PVC with high sensitivity, specificity, and predictive accuracy.

CONCLUSIONS

Although FW-VT/PVC has a relatively low prevalence, it has several distinctive ECG characteristics and detailed ECG analysis can differentiate it from Sep-VT/PVC.