Implication of the distinctive bipolar intracardiac electrograms for ventricular arrhythmias arising from different regions of ventricular outflow tract

AIMS

To investigate the characteristics of bipolar intracardiac electrograms (bi-EGMs) in target sites of ventricular arrhythmias (VAs) originating from different regions of ventricular outflow tract (VOT).

METHODS AND RESULTS

Two hundred and seventy patients undergoing first-time ablation for VAs originated from distal great cardiac vein (DGCV), aortic sinus cusps (ASCs), or pulmonary sinus cusps (PSCs) were enrolled in present study. Local intracardiac bipolar recordings on 243 successful sites and 506 attempted but unsuccessful ablation sites were analysed. Specific potentials in bi-EGMs on successful sites were more common compared with unsuccessful sites (76.95%, 187/243 vs. 25.49%, 129/506, P < 0.05). A total of 60.00% (81/135) patients in ASCs group presented a presystolic short-duration fractionated potential, higher than 23.21% (13/56) in DGCV and 23.08% (12/52) in PSCs (all P < 0.05); 44.23% (23/52) patients in PSC group showed a presystolic high-amplitude discrete potential, while 1.79% (1/56) in DGCV and 2.22% (3/135) in ASCs (all P < 0.05); 41.07% (23/56) patients in DGCV group showed bi-EGMs of presystolic long-duration multicomponent fractionated potential, which was significantly higher than 3.85% (2/52) in PSCs and 4.44%(6/135) in ASCs (all P < 0.05).

CONCLUSION

Distinctive morphology of bi-EGMs during VAs can be found in different regions of VOT, which probably due to changes in the arrangements of myocardial sleeves. Correct identification and better understanding of the distinctive features of these bi-EGMs with regards to the anatomic location was important, the presence of specific potentials may add help in successful ablation.

A Simplified Two-Stepwise Electrocardiographic Algorithm to Distinguish Left from Right Ventricular Outflow Tract Tachycardia Origin

BACKGROUND

There are several electrocardiographic algorithms to predict the origin of idiopathic outflow tract ventricular arrhythmias (OT-VAs). This study aimed to develop a more accurate and efficient stepwise electrocardiographic algorithm to discriminate left ventricular outflow tract (LVOT) from right ventricular outflow tract (RVOT) origin.

METHODS AND RESULTS

We analyzed 12-lead electrocardiographic characteristics of 173 consecutive OT-VAs patients who underwent successful radiofrequency catheter ablation in the RVOT (n = 124) or LVOT (n = 49). Based on the areas under the receiver operating characteristic curves, the combination of transitional zone (TZ) index <0 and V2S/V3R index ≤1.5 exhibited 93.5% sensitivity, 85.9% specificity, and 87.3% accuracy. A further analysis was performed in the 71 OT-VAs with a V3-lead precordial transition. The sensitivity, specificity, and accuracy of the integration of V2S/V3R index ≤1.5 and R-wave deflection interval in lead V3 >80 ms were 91.7, 83.1, and 85.9%, respectively. In the prospective evaluation, the combination of TZ index and V2S/V3R index could identify the correct origin sites with 91.2% accuracy in the overall analysis, and the integration of V2S/V3R index ≤1.5 and R-wave deflection interval in lead V3 >80 ms exhibited 94% accuracy in V3-lead precordial transition.

CONCLUSIONS

The combination of TZ index <0 and V2S/V3R index ≤1.5 is a simple and efficient stepwise electrocardiographic algorithm for predicting LVOT origin. For the OT-VAs with a V3-lead precordial transition, the integration of V2S/V3R index ≤1.5 and R-wave deflection interval in lead V3 >80 ms would be a better choice.

Electrocardiographic criteria of epicardial ventricular tachycardia with anterior origin

BACKGROUND

ECG criteria for identifying an epicardial origin of ventricular tachycardia (VT) have mainly been described for VTs with basal-superior and lateral origin.

OBJECTIVE

The aim of this study was to determine ECG criteria for epicardial VTs with anterior origin as a guide for trans-pericardial ablation.

RESULTS

Among 22 patients undergoing successful ablation of VTs from the anterior myocardial wall, 14 patients underwent endocardial ablation and 8 patients underwent epicardial ablation. VTs with anterior origin ablated epicardially had widened QS complexes in precordial leads with staircase-shaped notching and slowing of the descent to the nadir of S. In comparison, endocardial VTs with anterior origin usually had narrower QS complexes with a smooth and fast downstroke to the nadir of S. The duration of the negative pseudodelta wave was longer in epicardial VTs (55 ± 12 ms) compared to endocardial VTs (22 ± 12 ms). The interval "time to the nadir of S" in patients with anterior VT origin was longer in epicardial VTs (121 ± 16 ms) than in endocardial VTs (80 ± 22 ms). The QRS duration was also longer in patients with epicardial origin (212 ± 19 ms) than with endocardial VT origin (166 ± 30 ms).

CONCLUSIONS

Epicardial origin of VTs arising from the anterior myocardial wall produces a slowing, widening and staircase-shaped notching in the initial VT-QS complex. Thus, the morphology of the initial part of the QS complex in precordial leads can be used as a guide for trans-pericardial ablation of VTs with anterior origin.

Left ventricular outflow tract arrhythmias with divergent QRS morphology: mapping of different exits and ablation strategy

BACKGROUND

Ventricular arrhythmias (VAs) from the left ventricular outflow tract (LVOT) can have multiple exits exhibiting divergent ECG features.

METHODS

In a series of 131 patients with VAs with LVOT origin, 10 patients presented with divergent QRS morphologies. Multisite endo- and epicardial mapping of different exit sites was performed.

RESULTS

The earliest ventricular activity of 23 LVOT VAs in 10 patients was detected in the endocardium of the LV in 7 patients, the aortic sinuses of Valsalva (SoV) in 3 patients, the distal coronary sinus in 6 patients, the anterior interventricular vein in 3 patients, and the posterior right ventricular outflow tract (RVOT) in 4 patients. Simultaneous elimination of two divergent QRS morphologies of LVOT VAs by ablation from a single site was achieved in 5 patients (aorto-mitral continuity in 3 patients, SoV and RVOT in each 1 patient) using a mean maximum ablation energy of 46 ± 5 W. Sequential ablation from two or three different sites, including trans-pericardial and distal coronary sinus ablation in each 2 patients, led to elimination of the divergent VA QRS morphologies in the other 5 patients. During the follow-up of 28 ± 29 months, 4 of the 10 patients had recurrence of at least one LVOT VA. A 43-year-old patient with muscular dystrophy Curschmann-Steinert had recurrence of sustained LVOT VTs and died of sudden cardiac death.

CONCLUSIONS

Multisite mapping of different exit sites of LVOT VAs can guide ablation of intramural foci but the recurrence rate after initially successful ablation was high.

Long-Term Results After Single and Multiple Procedures of Ablation of Ventricular Tachycardia

INTRODUCTION

The aim of this study was to assess long-term results after single and multiple procedures of catheter ablation of ventricular tachycardia (VT). While it is generally accepted that multiple procedures are sometimes necessary in order to achieve long-term clinical success, the literature on this issue displays wide variability.

METHODS

We assessed the outcome of 160 consecutive patients who underwent 214 ablation procedures in the period 2008 to May 2015: 93 had overt structural heart disease (SHD) (previous myocardial infarction in 74 cases) and 67 had no SHD.

RESULTS

After the first procedure, the 1-year actuarial recurrence rates were 25% in patients with SHD and 5% in those without. However, recurrences increased progressively after the first year, reaching 46% and 35%, respectively, at 5 years. Overall, VT recurred in 35/93 (38%) patients with SHD and 22/67 (33%) patients without. Redo (1 to 4) procedures were performed in 28 (20%) patients with SHD and 18 (27%) patients without. After the last procedure, the 1-year actuarial recurrence rates were 5% in patients with SHD and 7% in those without, and the corresponding rates at 5 years were 23% and 7%. During follow-up, 21 patients died (all in the SHD group): no death was related to VT recurrence.

CONCLUSIONS

During long-term follow-up, VT frequently recurs after the first procedure, both in patients with SHD and in those without; multiple procedures are needed in order to increase the success rate.

Epicardial Ventricular Tachycardia Ablation for Which Patients?

With the widespread use of implantable cardioverter-defibrillators, an increasing number of patients present with ventricular tachycardia (VT). Large multicentre studies have shown that ablation of VT successfully reduces recurrent VT and this procedure is being performed by an increasing number of centres. However, for a number of reasons, many patients experience VT recurrence after ablation. One important reason for VT recurrence is the presence of an epicardial substrate involved in the VT circuit which is not affected by endocardial ablation. Epicardial access and ablation is now frequently performed either after failed endocardial VT ablation or as first-line treatment in selected patients. This review will focus on the available evidence for identifying VT of epicardial origin, and discuss in which patients an epicardial approach would be benefitial.