Clinical/Electrophysiological Characteristics of Infra-Nodal Wenckebach in Patients with Indication for Permanent Ventricular Pacing: A Prospective Study.

BACKGROUND: Infra-nodal Wenckebach is rare and is not well characterized. OBJECTIVES: We prospectively studied clinical and electrophysiological characteristics of patients with atrioventricular (AV) Wenckebach with an indication for permanent ventricular pacing. METHODS: Over a 2-year-period, all subjects with an indication for permanent ventricular pacing underwent targeted pre-implant electrophysiological study. Clinical/electrophysiologic characteristics at presentation and ventricular pacing percentage at 6-month follow-up were evaluated. RESULTS: A total of 163 patients [median age 68 (IQR 60-74) years, male 59%, median QRS duration 110 (90-130) ms, complete AV block in 123 (69.3%)] were included. AV Wenckebach was noted in 22 (13.4%) patients [median age 70 (63-76.5) years, male 54%, median QRS duration 120 (110-140) ms] and classified as infra-nodal (12/163 or 7.3%) vs. AV nodal (10/163 or 6.1%). Patients with infra-nodal Wenckebach (Infra-His in all), when compared to AV nodal Wenckebach, demonstrated higher frequency with LVEF <40% (41.7% vs. 0%, p=0.04), longer median HV interval (90 vs. 49 ms, p=0.005), lower frequency of isolated 1st degree AV block (8.3% vs. 60%, p=0.002), higher frequency of right bundle branch block with left-anterior fascicular block (75% vs. 10%, p=0.02), lesser PR increment at onset of AVW (20.5 vs. 80 ms, p=0.002), and onset of 2:1 AV block at longer cycle lengths (91.7% vs. 20%, p=0.002). CONCLUSIONS: Among patients referred for pacemaker implantation, infra-nodal Wenckebach was present in 27.5% (11/40) of patients without complete AV block. It was as frequent as AV nodal Wenckebach and associated with characteristic electrophysiologic findings.

Septal Venous Channel Perforation during Left Bundle Branch Area Pacing: A Prospective Study.

OBJECTIVES: To characterize the diagnosis, frequency, and procedural implications of septal venous channel perforation during left bundle branch area pacing (LBBAP). METHODS: All consecutive patients undergoing LBBAP over an 8-month period were prospectively studied. During lead placement, obligatory septal contrast injection was performed twice, at initiation (implant entry zone) and completion (fixation zone). An intuitive fluoroscopic schema using orthogonal views (LAO/RAO) and familiar landmarks is described. Using this, we resolved zonal distribution (I-VI) of lead position on the ventricular septum and its angulation (post-fixation angle θ). Subjects with/without septal venous channel perforation were compared. RESULTS: Sixty-one-patients [Male 57.3%, Median Age (IQR) 69.5(62.5-74.5) years] were enrolled. Septal venous channel perforation was observed in 8 (13.1%) patients [Male 28.5%, Median Age (IQR) 64(50-75) years]. They had higher frequency of, i) right-sided-implant (25% vs. 1.9%, p = 0.04), ii) fixation in zone III at the mid-superior septum (75% vs 28.3%, p = 0.04), iii) steeper angle of fixation- median θ (IQR) [19(10-30)° vs. 5(4-19)°, p = 0.01), and iv) longer median penetrated-lead-length (IQR) [13(10-14.8) vs. 10(8.5-12.5)mm, p = 0.03]. Coronary sinus drainage of contrast was noted in 5 (62.5%) patients. Abnormal impedance drops during implantation (12.5% vs. 5.7%, p = NS) were not significantly different. CONCLUSION: When evaluated systematically, septal venous channel perforation may be encountered commonly after LBBAP. The fiducial reference framework described using fluoroscopic imaging identified salient associated findings. This may be addressed with lead repositioning to a more inferior location and are not associated with adverse consequence acutely or in early follow-up.

A case of exaggerated exuberance: Iatrogenic atrioventricular block/intra-Hisian Wenckebach during conduction system pacing.

Isolated sinus node dysfunction with its pursuant long-term risk for atrioventricular (AV) conduction disease poses a unique dilemma for proponents of CSP due to paucity of imprimatur guidelines. In such scenarios, the risk and prognosis of iatrogenic AV block is not well elucidated but is a valid concern. We report a case where CSP was complicated by iatrogenic AV block and peculiarly the rare phenomenon of intra-Hisian Wenckebach.

An unusual site of ablation for a ventricular tachycardia.

Scar-related ventricular tachycardia (VT) ablation involves localizing the critical isthmuses by overdrive pacing maneuvers and three-dimensional activation mapping. Implantable prosthetic devices have been known to complicate this by covering sites of potential isthmuses. We herein present a sentinel report of scar-VT ablation with a protected isthmus localized over an endothelialized post-myocardial infarction ventricular septal defect occluder device.

Open window mapping for redo accessory pathway ablation in Ebstein anomaly.

Accessory pathway ablation in Ebstein anomaly can be significantly more challenging than in structurally normal hearts. An alternative to the conventional approach to mapping APs is to detect points with a high-density mapping catheter based on an automated detection algorithm using open window mapping. It detects the sharpest signal at each point with high-density mapping rather than relying on the origin of the local electrogram to localize the pathway and determine a site for successful ablation. We herein report the first case in literature of a redo-accessory pathway ablation in Ebstein anomaly using this technique.

Caveats related to conduction system pacing utilizing a proprietary deflectable mapping catheter with a stylet-driven lead.

BACKGROUND: Hitherto, lumen less leads (LLLs) were routinely utilized for conduction system pacing (CSP). We report the largest experience using stylet-driven leads (SDLs) with a deflectable mapping catheter for CSP. METHODS: Patients were prospectively and sequentially enrolled for CSP with SDL between June, 2021 and November, 2022 to (i) a novel deflectable mapping catheter (AgilisHisProTM, Abbott) (Group A) or (ii) a fixed curve sheath (Selectra3D, Biotronik) (Group B) in a 1:1 non-randomized fashion. The primary aim was to evaluate safety, feasibility, and efficacy of the CSP using SDL and deflectable mapping catheter (Group A) while reporting procedural success and intermediate-term follow-up. RESULTS: Seventy-nine patients (59.4%M, mean age 67.2+/-10.6 years) were allocated to either (i) Group A (n = 40) or (ii) Group B (n = 39). In Group A (n = 40, 50% M, mean age 67.2+/-9.5 years, follow-up 210.7 + 25.1days), His bundle pacing (HBP) was the default strategy with left bundle branch area pacing (LBBaP) for bailout. Procedural success with HBP was feasible in 17/40 (42.5%) patients with remaining 23/40 (57.5%) needing LBBaP bailout. After initial learning curve, a manual septal curve was introduced to successfully aid LBBaP in 6/23 (26.1%) cases. Procedural and follow-up parameters did not differ significantly in HBP vs. LBBaP. Head-to-head comparison was not performed between the groups owing to different default protocols (HBP-Group A, Discretionary-Group B). CONCLUSIONS: Use of SDL with single-curve deflectable mapping catheter was safe, feasible and yielded moderate procedural success with HBP and frequently needed a LBBaP bailout strategy. In approximately one-fourth of the latter, an out-of-plane manual septal curve was needed to optimize LBBaP.

Interventions in the diagnosis and adoption of pacemaker therapy in sinus node dysfunction patients: Results from the IMPROVE Brady study.

AIMS: IMPROVE Brady assessed whether a process improvement intervention could increase adoption of guideline-based therapy in sinus node dysfunction (SND) patients. METHODS: /Results: IMPROVE Brady was a sequential, prospective, quality improvement initiative conducted in India and Bangladesh. Patients with symptomatic bradycardia were enrolled. In Phase I, physicians assessed and treated patients per standard care. Phase II began after implementing educational materials for physicians and patients. Primary objectives were to evaluate the impact of the intervention on SND diagnosis and pacemaker (PPM) implant. SF-12 quality of life (QoL) and Zarit burden surveys were collected pre- and post-PPM implant. A total of 978 patients were enrolled (57.7 ± 14.8 years, 75% male), 508 in Phase I and 470 in Phase II. The diagnosis of SND and implantation of PPM increased significantly from Phase I to Phase II (72% vs. 87%, P < 0.001 and 17% vs. 32%, P < 0.001, respectively). Pacemaker implantation was not feasible in 41% of patients due to insurance/cost barriers which was unaltered by the intervention. Both patient QoL and caregiver burden improved at 6-months post-PPM implant (P < 0.001). CONCLUSIONS: A process improvement initiative conducted at centers across India and Bangladesh significantly increased the diagnosis of SND and subsequent treatment with PPM therapy despite the socio-economic constraints.

Right atrial appendage tachycardia: A rare cause of tachycardia induced cardiomyopathy in a 4-year-old child.

We present a rare case of tachycardiomyopathy in a 4-year-old girl. The child had incessant atrial tachycardia (AT) and refractory heart failure. Right atrial appendage (RAA) was localised as the source of the ectopic tachycardia. The child underwent successful radiofrequency ablation (RFA) using 3-D electroanatomical mapping. Fluoroscopy was used sparingly only to rule out underlying anomalies. The left ventricular functions returned to normal by one month after the procedure. RAA AT is rare in very young children and usually necessitates surgical appendectomies. RFA is a challenge in such age groups and there are very few published literature on RAA AT in very young children.

Predictors of short-term outcomes in patients undergoing percutaneous coronary intervention in cardiogenic shock complicating STEMI-A tertiary care center experience.

BACKGROUND: Studying the outcomes in patients presenting with cardiogenic shock with ST-segment elevation myocardial infarction (CS-STEMI) and undergoing primary or rescue percutaneous coronary intervention (PCI) may give an insight to the unmet needs in STEMI-care in our region and may help in future recommendations in improving survival. MATERIALS AND METHODOLGY: During the period from January 2001- June 2017, there were 114 patients included in the study. The demographic, clinical and angiographic characteristics were compared between the survivors and non-survivors. All these variables were also compared between two-time frames (Phase 1- January 2001 to June 2007; Phase 2- July 2007 to June 2017). RESULTS: Among patients undergoing PCI for STEMI, 7.5% were in cardiogenic shock. In-hospital mortality for the patients included in the study was 53.5%. Total ischemic time (OR=0.99, 0.99-1; p=0.02), left ventricular ejection fraction (LVEF) (OR=0.90, 0.82-0.98; p=0.02), need for cardio-pulmonary resuscitation (OR=0.12, 0.24-0.66; p=0.01), and post PCI TIMI flows (OR=0.08, 0.02-0.29; p<0.001) were the significant determinants of in-hospital mortality in the regression analysis. There was no significant change in mortality between the two phases of the study, though there was a reduction in total ischemic and door-to-balloon times, transfer admissions, use of thrombolytics, glycoprotein IIb/IIIa inhibitors, intra-aortic balloon pump, and mechanical ventilation in phase 2. CONCLUSION: Patients presenting in CS-STEMI and undergoing PCI continue to experience high mortality rates, despite improvements in total ischemic times. Further improvement in the systems-of-care are required to bring about reduction in mortality in this high-risk subset.

Initial outcome following invasive cardiac electrophysiologic studies and radiofrequency ablation of atrial fibrillation.

BACKGROUND: Cardiac electrophysiologic study and radiofrequency ablation (RFA) have become an established mode of treatment for patients with refractory arrhythmias. These procedures are carried out regularly at the cardiac catheterization laboratory of Madras Medical Mission India. OBJECTIVE: The purpose of this study was to evaluate our experience with cardiac electrophysiologic studies (EPS) and RFA catheter of atrial fibrillation (AF). MATERIALS AND METHODS: This was a retrospective study carried out in the Cardiac Electrophysiology Department of the Institute of Cardiovascular Diseases, Madras Medical Mission, India. All cases diagnosed to have AF following cardiac EPS between January 2010 and April 2014 was selected for the study. The records, which were obtained from the Cardiac Electrophysiology Clinical Research Office of Madras Medical Mission, were reviewed. Forty-nine cases were chosen for analysis, using SPSS statistical software version 15. RESULTS: There were 49 patients, 23 males and 26 females. The mean age was 57.53 years. Commonly associated diseases were diabetes mellitus 8 (16.3%), hypertension 18 (36.7%), and coronary heart disease 14 (28.5%). The ventricular rate was rapid most cases (91.2%). AF was diagnosed as being paroxysmal in 40 (81.6%), persistent in 5 (10.2%), chronic in 3 (6.1%), and lone in 1 (2.0%). Ablation was carried out in 28 (57.1%), the success rate being 90% for pulmonary vein isolation, and 90.9% for atrioventricular node ablation. Complication rate was 2.04%. CONCLUSIONS: Treatment of AF by RFA is highly effective and safe.

Risk scoring system to predict contrast induced nephropathy following percutaneous coronary intervention.

BACKGROUND: Contrast induced nephropathy (CIN) is associated with significant morbidity and mortality after percutaneous coronary intervention (PCI). The aim of this study is to evaluate the collective probability of CIN in Indian population by developing a scoring system of several identified risk factors in patients undergoing PCI. METHODS: This is a prospective single center study of 1200 consecutive patients who underwent PCI from 2008 to 2011. Patients were randomized in 3:1 ratio into development (n = 900) and validation (n = 300) groups. CIN was defined as an increase of ≥25% and/or ≥0.5 mg/dl in serum creatinine at 48 hours after PCI when compared to baseline value. Seven independent predictors of CIN were identified using logistic regression analysis - amount of contrast, diabetes with microangiopathy, hypotension, peripheral vascular disease, albuminuria, glomerular filtration rate (GFR) and anemia. A formula was then developed to identify the probability of CIN using the logistic regression equation. RESULTS: The mean (±SD) age was 57.3 (±10.2) years. 83.6% were males. The total incidence of CIN was 9.7% in the development group. The total risk of renal replacement therapy in the study group is 1.1%. Mortality is 0.5%. The risk scoring model correlated well in the validation group (incidence of CIN was 8.7%, sensitivity 92.3%, specificity 82.1%, c statistic 0.95). CONCLUSION: A simple risk scoring equation can be employed to predict the probability of CIN following PCI, applying it to each individual. More vigilant preventive measures can be applied to the high risk candidates.