Sreevilasam Pushpangadhan Abhilash

Paradoxical Increase in Stimulus to Atrium Interval During Para-Hisian Pacing

A 40-year-old gentleman has undergone electrophysiological study for paroxysmal palpitation. Surface electrocardiogram during sinus rhythm showed no preexcitation. The AH and HV intervals during sinus rhythm were 104 and 40 ms, respectively. There was no dual AV node physiology demonstrated. Para-Hisian pacing was performed to exclude a septal bypass tract which showed an interesting response (Fig. 1). Para-Hisian pacing demonstrated relatively broader (104 ms) and narrow (60 ms) QRS morphologies with stimulus to atrium (S–A) intervals of 156 and 175 ms, respectively. The atrial activation sequence with the 2 QRS morphologies is not similar (Fig. 2). The ventricular activation has also changed from the left to the right panels, with the proximal left ventricle (as suggested by the V electrogram [EGM] in the coronary sinus [CS] electrodes 5, 6, 3, 4, 1, and 2) and para-Hisian right ventricle are relatively early when the QRS

Radial left ventricular dyssynchrony by speckle tracking in apical versus non apical right ventricular pacing- evidence of dyssynchrony on medium term follow up

Introduction: To study effects of various sites of right ventricular pacing lead implantation on left ventricular function by 2-dimensional (2D) speckle tracking for radial strain and LV dyssynchrony. Methods: This was retrospective prospective study. Fifteen patients each with right ventricular (RV) apical (RV apex and apical septum) and non-apical (mid septal and low right ventricular outflow tract [RVOT]) were programmed to obtain 100% ventricular pacing for evaluation by echo. Location and orientation of lead tip was noted and archived by fluoroscopy. Electrocardiography (ECG) was archived and 2D echo radial dyssynchrony was calculated. Results: The baseline data was similar between two groups. Intraventricular dyssynchrony was significantly more in apical location as compared to non-apical location (radial dyssynchrony: 108.2 ± 50.2 vs. 50.5 ± 24, P < 0.001; septal to posterior wall delay [SLWD] 63.5 ± 27.5 vs. 34 ± 10.7, P < 0.001, SPWD 112.5 ± 58.1 vs. 62.7 ± 12.1, P = 0.003). The left ventricular ejection fraction was decreased more in apical location than non apical location. Interventricular dyssynchrony was more in apical group but was not statistically significant. The QRS duration, QTc and lead thresholds were higher in apical group but not statistically significant. Conclusion: Pacing in non apical location (RV mid septum or low RVOT) is associated with less dyssynchrony by specific measures like 2D radial strain and correlates with better ventricular function in long term.

Wide QRS tachycardia with RBBB morphology, right inferior quadrant axis, and 1:1 AV relation: What is the mechanism?

Department of Cardiology, SreeChitra Tirunal Institute forMedical Sciences and Technology, Thiruvananthapuram, Kerala, India Correspondence NarayananNamboodiri,MBBS,MD,DM,DepartmentofCardiology, SreeChitraTirunal Institute forMedical Sciences andTechnology, Thiruvananthapuram,Kerala, India –695011. Email: kknnamboodiri@gmail.com Disclosures:Theauthorshavenocompeting interests, fundingor financial relationships todisclose.

Response of LBBB tachycardia to an atrial premature beat: What is the mechanism?: MOHANAN NAIR et al .

Department of Cardiology, SreeChitra Tirunal Institute forMedical Sciences and Technology, Thiruvananthapuram, Kerala, India Correspondence NarayananNamboodiri,MBBS,MD,DM,DepartmentofCardiology, SreeChitraTirunal Institute forMedical Sciences andTechnology, Thiruvananthapuram,Kerala, India. Email: kknnamboodiri@gmail.com Disclosures Theauthorshavenocompeting interests, funding, orfinancial relationships todisclose.

Atrial premature beat on wide QRS tachycardia with LBBB morphology. What is the mechanism?: MOHANAN NAIR et al.

Department of Cardiology, SreeChitra Tirunal Institute forMedical Sciences and Technology, Thiruvananthapuram, Kerala, India Correspondence NarayananNamboodiri,MBBS,MD,DM,DepartmentofCardiology, SreeChitraTirunal Institute forMedical Sciences andTechnology, Thiruvananthapuram,Kerala 695011, India. Email: kknnamboodiri@gmail.com Disclosures Theauthorshavenocompeting interests, fundingorfinancial relationships todisclose.

Bundle branch alternans with PR alternans. What is the mechanism

Department of Cardiology, SreeChitra Tirunal Institute forMedical Sciences and Technology, Thiruvananthapuram, Kerala, India Correspondence NarayananNamboodiri,MBBS,MD,DM,DepartmentofCardiology, SreeChitraTirunal Institute forMedical Sciences andTechnology, Thiruvananthapuram,Kerala 695011, India. Email: kknnamboodiri@gmail.com Disclosures Theauthorshavenocompeting interests, fundingorfinancial relationships todisclose.

RBBB tachycardia with north-west axis. What is the mechanism?☆

RBBB tachycardia with NW axis is considered to be VT unless proved otherwise. However underlying conduction system disease can produce electrocardiographic patterns suggestive of bundle branch block with extreme left axis which can cause difficulty in differentiating VT from SVT as in this case.

An Unusual Cause of Heart Failure in a Young Man

A 21year old gentleman was admitted with shortness of breath and heart failure. He was noted to have incessant supraventricular tachycardia which was refractory to pharmacological and electrical cardioversion. Electrophysiology study revealed focal atrial tachycardia from an unusual location which was successfully ablated.

Electrical Cardioversion of an Irregular Narrow QRS Tachycardia to a Regular Narrow QRS Tachycardia

A 45-year-old woman was referred for radiofrequency catheter ablation of narrow QRS tachycardia that was terminated with intravenous adenosine. Twelve-lead ECG was normal during sinus rhythm. The electrophysiological study showed an AH interval of 68 ms and histoventricular (HV) interval of 42 ms during sinus rhythm. Ventricular pacing showed concentric activation of the atrium with decremental conduction. Anterograde dual atrioventricular (AV) node physiology was demonstrated. Burst atrial pacing induced atrial fibrillation (AF). Upon cardioversion, AF terminated

Observations During Parahisian Entrainment

A 45-year-old man has undergone electrophysiological study for paroxysmal palpitation. Surface electrocardiogram during sinus rhythm was consistent with left lateral accessory pathway. The atriohisian (AH) and hisioventricular (HV) intervals during sinus rhythm were 84 ms and 10 ms, respectively, and earliest ventricular activation was recorded at coronary sinus (CS) distal dipole that was placed at the distal CS. A regular narrow QRS tachycardia was easily and reproducibly induced with atrial pacing and ventricular pacing protocols that was confirmed to be orthodromic atrioventricular reentrant tachycardia (ORT) involving the left lateral pathway. ParaHisian entrainment was performed during tachycardia that showed an interesting response (Figs. 1 and 2). During paraHisian entrainment, there are 3 competing and interacting waves, namely the AV reentrant tachycardia circuit, His bundle-right bundle (HB-RB) capture circuit, and right ventricular (RV) paraHisian myocardial capture circuit. The retrograde atrial (A) activation sequence (RAAS) during tachycardia, HB-RB capture, and RV capture are the same with earliest atrial electrogram being recorded at CS distal dipole. On the other hand, the net stim to A (S-A) interval prolonged after loss of His capture. This is best explained