Radiofrequency catheter ablation of symptomatic ventricular ectopic beats originating in the right outflow tract

Spatial Distribution of Idiopathic Ventricular Arrhythmias Originating Around the Pulmonary Root: Lessons From Intracardiac Echocardiography

OBJECTIVES

The purpose of this study was to investigate the spatial distribution of ventricular arrhythmias (VAs) and their relationship with anatomic landmarks in the right ventricular outflow tract (RVOT).

BACKGROUND

Although controversy has mainly focused on whether VAs ablated in the RVOT originate above or below the pulmonary sinus, little is known about their actual distribution.

METHODS

We performed mapping and ablation in the reconstructed RVOT using intracardiac echocardiography (ICE) and summarized the spatial electroanatomic characteristics of RVOT-VAs.

RESULTS

A total of 50 VAs were recruited and were distributed among the 3 subregions: the pulmonary sinuses (19 of 50, 38%), sinus junctions (18 of 50, 36%), and infundibulum (13 of 50, 26%). In total, 70% (35 of 50) of ablation targets were within 10 mm (mean 4.3 ± 2.7 mm) of the pulmonary valve hinge point. An ablation target with both amplitude ≤1.14 mV and duration ≥101.5 milliseconds predicted an origin above the pulmonary sinus with a sensitivity of 84.2% and specificity of 84.4%. For the ablation targets (13 of 50, 26%) located in the infundibulum of the RVOT, 4 were surrounded by trabeculations, whereas only 1 ablation target in the sinus junction abutted the trabeculation (30.8% vs 5.6%).

CONCLUSIONS

Ablation targets of RVOT-VAs were mainly distributed around the hinge point of the pulmonary valve and the trabeculation of the infundibulum. ICE can clearly and precisely locate those anatomic landmarks of the RVOT.

Which Is The Appropriate Arrhythmia Burden To Offer RF Ablation For RVOT Tachycardias?

Premature ventricular complexes (PVCs) and ventricular tachycardia (VT) in patients with structurally normal hearts originate from the right ventricular outflow tract (RVOT) in the majority of cases. In the last few decades catheter ablation of these arrhythmias has been proven to be effective. RVOT VT/PVCs may cause disabling symptoms or arrhythmia induced cardiomyopathy. However, the PVC burden at which catheter ablation should be recommended is still controversial. What adds to the controversy is why some patients with only a low number of PVCs can be highly symptomatic and may even develop arrhythmia induced cardiomyopathy, whilst others may have a higher PVC/VT burden and remain asymptomatic and do not develop cardiomyopathy for a long period of time. Therefore, although catheter ablation of RVOT PVCs has high success and low complication rates, the time point of when ablation should be recommended is currently still under debate. This review discusses the treatment strategies and prognosis for RVOT tachycardias and focuses on the question of which arrhythmia burden is appropriate to offer RF ablation.

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.

One-year outcome after radiofrequency catheter ablation of symptomatic ventricular arrhythmia from right ventricular outflow tract

Although ventricular premature complexes (VPCs) in patients without structural heart disease are benign, many patients experience disabling symptoms. Many patients need long-term medication, which is often ineffective and may have adverse effects. Radiofrequency catheter ablation (RFCA) may be an alternative treatment. RFCA was performed in 33 patients with severely symptomatic VPCs that were refractory to medication. Mean VPCs were 23,987 +/- 2,077 beats/24 hours. Twenty-four-hour ambulatory electrocardiographic monitoring, quality of life, and symptoms were assessed at a screening visit and 1 and 12 months after RFCA. RFCA was successfully performed in 32 patients (97%). This resulted in a significant improvement in symptoms, severity of ventricular arrhythmia, and quality of life at 1 and 12 months after the procedure. There were no major complications related to the procedure. Eight patients (24%) had residual arrhythmia. Five of them underwent repeated ablation with successful results. Thus, catheter ablation is a safe and effective treatment for symptomatic ventricular arrhythmia from the right ventricular outflow tract. It also improves the quality of life. Catheter ablation is a viable alternative to drugs in the presence of disabling symptoms.

Catheter ablation of a monofocal premature ventricular complex triggering idiopathic ventricular fibrillation

A 62 year old man was admitted for evaluation of recurrent episodes of syncope. A surface ECG showed frequent repetitive premature ventricular complexes of right ventricular outflow tract origin. Ventricular fibrillation was inducible by programmed electrical stimulation but otherwise cardiac evaluation was unremarkable. A diagnosis of idiopathic ventricular fibrillation was made and an implantable cardioverter-defibrillator (ICD) was installed. However, spontaneous ventricular fibrillation recurred, requiring repeated ICD discharges. The ventricular fibrillation was reproducibly triggered by a single premature ventricular complex with a specific QRS morphology. Radiofrequency catheter ablation was carried out to eradicate this complex. No ventricular fibrillation has developed after this procedure, and the patient does not require drug treatment.

Catheter ablation of a monofocal premature ventricular complex triggering idiopathic ventricular fibrillation

A 62 year old man was admitted for evaluation of recurrent episodes of syncope. A surface ECG showed frequent repetitive premature ventricular complexes of right ventricular outflow tract origin. Ventricular fibrillation was inducible by programmed electrical stimulation but otherwise cardiac evaluation was unremarkable. A diagnosis of idiopathic ventricular fibrillation was made and an implantable cardioverter-defibrillator (ICD) was installed. However, spontaneous ventricular fibrillation recurred, requiring repeated ICD discharges. The ventricular fibrillation was reproducibly triggered by a single premature ventricular complex with a specific QRS morphology. Radiofrequency catheter ablation was carried out to eradicate this complex. No ventricular fibrillation has developed after this procedure, and the patient does not require drug treatment.

Independent autonomic modulation of sinus node and ventricular myocardium in healthy young men during sleep

INTRODUCTION

The aim of this study was to investigate whether autonomic modulation of ventricular repolarization may spontaneously differ from that of the sinoatrial node.

METHODS AND RESULTS

Onset of P waves, QRS complexes, and the apex and end of T waves were detected beat to beat in high-resolution ECGs from nine healthy young men during the night. There were time-dependent fluctuations in the QT/RR slopes of consecutive 5-minute segments that could not be explained by the mean RR cycle length of the respective segment. Because the variability found in QT intervals could not be explained by either possible effects of rate dependence or hysteresis, autonomic effects were obvious. Power spectral analysis was performed for consecutive 5-minute segments of PP and QT tachograms. In a given subject, trends in the time course of low-frequency (LF) and high-frequency (HF) power in PP and QT often were similar, but they were quite different at other times. The mean LF/HF ratio for QTend (0.75 +/- 0.1) was different from that of PP (1.8 +/- 0.2; P = 0.002), indicating differences in sympathovagal balance at the different anatomic sites. Furthermore, at a given mean heart rate, averaged QT intervals were different on a time scale of several minutes to hours. The QT/RR slope of 5-minute segments correlated significantly with the HF power of QT variability but not with that of PP variability, indicating effects of the autonomic nervous system on ventricular action potential restitution.

CONCLUSION

These differences demonstrate that changes in sinus node automaticity are not necessarily indicative of the autonomic control of ventricular myocardium.