Septal venous channel perforation during left bundle branch area pacing: a prospective study.

AIMS: To characterize the diagnosis, frequency, and procedural implications of septal venous channel perforation during left bundle branch area pacing (LBBAP). METHODS AND RESULTS: 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 at completion (fixation zone). An intuitive fluoroscopic schema using orthogonal views (left anterior oblique/right anterior oblique) 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 and without septal venous channel perforation were compared. Sixty-one patients {male 57.3%, median age [interquartile range (IQR)] 69.5 [62.5-74.5] years} were enrolled. Septal venous channel perforation was observed in eight (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 five (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 is not associated with adverse consequence acutely or in early follow-up.

Clinical/electrophysiologic characteristics of infranodal Wenckebach in patients with indication for permanent ventricular pacing: A prospective study.

BACKGROUND: Infranodal Wenckebach is rare and not well characterized. OBJECTIVE: We prospectively studied clinical and electrophysiologic characteristics of patients with atrioventricular (AV) Wenckebach with an indication for permanent ventricular pacing. METHODS: During a 2-year period, all patients with an indication for permanent ventricular pacing underwent targeted preimplantation electrophysiologic study. Clinical and electrophysiologic characteristics at presentation and ventricular pacing percentage at 6-month follow-up were evaluated. RESULTS: A total of 163 patients (median age, 68 [interquartile range, 60-74] years; male, 59%; median QRS duration, 110 [90-130] ms; complete AV block in 123 [75.5%]) 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 infranodal (12/163 [7.3%]) vs AV nodal (10/163 [6.1%]). Patients with infranodal Wenckebach (infrahisian in all), compared with AV nodal Wenckebach, demonstrated higher frequency with left ventricular ejection fraction ≤40% (41.7% vs 0%; P = .04), longer median HV interval (90 vs 49 ms; P = .005), lower frequency of isolated first-degree AV block (8.3% vs 60%; P = .02), higher frequency of right bundle branch block with left anterior fascicular block (75% vs 10%; P = .003), lesser PR increment at onset of AV Wenckebach (20.5 vs 80 ms; P = .002), and onset of 2:1 AV block at longer cycle lengths (91.7% vs 20%; P = .002). CONCLUSION: Of patients referred for pacemaker implantation, infranodal Wenckebach was present in 27.5% (11/40) without complete AV block. It was as frequent as AV nodal Wenckebach and associated with characteristic electrophysiologic findings.

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.

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.

Irregular ventricular tachycardia originating from the moderator band.

Ventricular tachycardias (VT) may initially show beat to beat oscillations but rapidly stabilize into a regular tachycardia with a stable cycle length. A persistently irregular ventricular tachycardia is a rare phenomenon. We report a rare case of an "irregular" ventricular tachycardia with so pronounced oscillations in cycle length that it was initially misdiagnosed as atrial fibrillation with aberrant conduction. This ventricular tachycardia was incessant and resulted in a tachycardia induced cardiomyopathy refractory to several antiarrhythmic drugs. Mapping of the right ventricle demonstrated that the tachycardia had a focal origin in the moderator band close to its insertion into the anterior papillary muscle. Radiofrequency ablation eliminated the tachycardia with eventual normalization of left ventricular function. The moderator band and anterior papillary muscle of the right ventricle are known to be the source of short-coupled ventricular premature beats and regular ventricular tachycardias. However, an "irregular" ventricular tachycardia has not been previously reported to arise from these structures.

Ventricular Functional Analysis in Congenital Complete Heart Block Using Speckle Tracking: Left Ventricular Epicardial Compared to Right Ventricular Septal Pacing.

BACKGROUND: Chronic right ventricular (RV) apical pacing in patients with congenital complete atrioventricular block (CCAVB) is associated with left ventricle (LV) dyssynchrony and dysfunction. Hence, alternative pacing sites are advocated. The aim of this study was to compare LV function using STE in selected patients with LV epicardial pacing (LVEp) vs. RV transvenous pacing (RVSp). METHODS: This was a single-center, retrospective study in patients with CCAVB who underwent permanent pacemaker implant at age ≤ 18 years. Age- and gender-matched patients with a normal heart anatomy and function served as the control group. LV function was comprehensively assessed by conventional 2D Echocardiography and speckle-tracking echocardiography (STE). RESULTS: We included 24 patients in the pacemaker group [27.6% male, mean age of 17.1 at last follow-up, follow-up duration of 8.7 years, RVSp (n = 9; 62.5%)] compared to 48 matched healthy controls. Shortening fraction (SF) and ejection fraction (EF) were normal and similar between cases and controls. However, STE detected abnormal LV function in the pacemaker group compared to controls. The former demonstrated lower/abnormal, Peak Longitudinal Strain myocardial (PLS Myo) [- 12.0 ± 3.3 vs. - 18.1 ± 1.9, p < 0.001] and Peak Longitudinal Strain endocardial (PLS endo) [- 16.1 ± 4.1 vs. 1.7 ± 1.7, p < 0.001]. STE parameters of LV function were significantly more abnormal in LVEp vs. RVSp subgroup as demonstrated by lower values for PLS Myo (- 10.1 ± 3.2 vs. - 13.1 ± 2.9, p = 0.03) and PLS Endo (- 13.8 ± 4.4 vs. - 17.5 ± 3.3, p = 0.03). CONCLUSION: STE was more sensitive in detecting subtle differences in LV function relative to standard conventional 2D echocardiography (SF and EF) in selected patients with CCAVB and a permanent pacemaker. Furthermore, STE demonstrated that transvenous RV septal pacing was associated with better LV systolic function preservation than LV epicardial pacing for comparable post-implant intervals.

Exercise Capacity in Patients with Pulmonary Atresia with Intact Ventricular Septum: Does the Type of Surgical Repair Matter?

Two standard surgical palliative options for neonates born with pulmonary atresia and intact ventricular septum (PA/IVS) include uni-or biventricular repair. Whenever feasible, the biventricular repair is considered to have better exercise capacity (XC) and outcomes. However, there is a paucity of data comparing objective XC between these two surgical techniques. Our aim was to compare XC, including longitudinal changes in patients with PA/IVS following uni-biventricular repair. We performed a single-center retrospective study of survivors with repaired PA/IVS who underwent comprehensive treadmill cardiopulmonary exercise testing. Initial and latest exercise parameters were compared for longitudinal analysis. Demographic and exercise parameters were collated. Peak oxygen uptake (VO2 in ml/kg/min), an indicator of maximal aerobic capacity, peak heart rate, and other measures of spirometry performed at the same time were collected. Recorded parameters included, (a) Percentage of predicted VO2 (% VO2) normalized for age, weight, height, and gender, (b) % oxygen (O2) pulse, (c) anaerobic threshold (AT), (d) Chronotropic index (CI), (e) % Breathing reserve, (f) Forced vital capacity (FVC), (g) % Forced Expiratory volume in 1 s (FEV1), (h) Maximum voluntary ventilation (MVV), and (i) VE/VCO2. Appropriate statistical tests were performed, and a p value < 0.05 was considered significant. A total of 35 patients (43% male, 57% univentricular repair) were included, with a mean (SD) age of 20.1(7.5) years. Patients with univentricular palliation demonstrated significantly impaired peak heart rate, chronotropic index (0.50 ± 0.2 vs. 0.90 ± 0.1, p = 0.02), VE/VCO2 (35.4 ± 5.0 vs. 30.2 ± 2.8, p = 0.001), and %FVC (78.3 ± 8.3 vs. 88.6 ± 15.1, p = 0.02). There was a trend towards reduction in % VO2 in the Fontan patients though it was statistically similar between the groups (68.4 ± 21.4 vs. 81.2 ± 18.9, p = 0.07). Longitudinal data were available for 11 patients in each group, and there was no longitudinal decline in their exercise parameters over similar intermediate follow-up duration [6.8 (UV) vs. 5.3 (BV) years]. We conclude that young survivors with PA/IVS with prior univentricular palliation demonstrated an objective impairment in their chronotropic parameters compared with the biventricular repair. However, this did not translate into a significant difference in their exercise capacity. There was no longitudinal decline in exercise capacity or other parameters over intermediate follow-up.

Cardiovascular Phenotypic Spectrum of 1p36 Deletion Syndrome.

Chromosome 1p36 deletion syndrome is a common genetic anomaly (prevalence: 1 in 5,000-1 in 10,000). Despite reports of cardiovascular involvement, the cardiovascular phenotypic spectrum of patients with 1p36 deletion syndrome is not well characterized. In this article, we reported the clinical course of a full-term African American boy with chromosome 1p36 deletion syndrome and neonatal onset of severe cardiac disease with moderate-to-severe biventricular dysfunction and severe pulmonary hypertension. Early neonatal onset presentation of 1p36 deletion syndrome is rare and might be associated with a more guarded prognosis. This case based study is supplemented by a comprehensive review of cardiovascular involvement in this relatively common genetic syndrome.

Exercise Capacity After Arterial Switch Operation in Patients with D-Transposition of Great Arteries: Does the Coronary Artery Anatomy Matter?

Variant coronary anatomy (VarCA) is frequent in D-Transposition of the great arteries (d-TGA). There are a paucity of data on the effect of the VarCA on the exercise capacity (XC) in patients with repaired d-TGA. This retrospective study included patients with d-TGA who underwent an arterial switch operation (ASO) and had at least one cardiopulmonary exercise test (CPET). Data from the treadmill CPET and simultaneously performed spirometry were collected. The parameters of CPET were compared between patients with usual anatomy vs. VarCA. Longitudinal changes in XC in patients with ASO were also analyzed. A total of 44 patients with either usual coronary anatomy (n = 27, 61%) or VarCA (n = 17, 39%) met inclusion criteria. There was no significant difference in oxygen consumption (%VO2) at initial CPET (104 vs. 100%, p = 0.53) between the two groups. Abnormal %VO2 (< 85%) was uncommon in both groups (n = 2, 7.4% vs. n = 4; 23.5%; p = ns). For longitudinal changes, there was no significant decline in %VO2 in either group: (i) usual coronary anatomy (n = 15, median follow-up 4.8 years, %VO2 111 vs. 108%; p = 0.306) and (ii) VarCA (n = 10, median follow-up 6.6 years, %VO2 106 vs. 92%; p = 0.441). Spirometry was abnormal in 25 (59.5%) patients [restrictive (n = 8, 19.0%), obstructive (n = 15, 35.7%), and mixed (n = 2, 4.8%)] butabnormal spirometry had no impact on the XC. Patients with d-TGA who underwent neonatal ASO uniformly exhibited good XC without any longitudinal decline on medium-term follow-up, regardless of coronary artery anatomy. Although frequent (60%), abnormal spirometry was not associated with reduced exercise capacity.

Wide complex tachycardia in a patient with non-ischemic cardiomyopathy: What is the diagnosis?

A 55-year-old male presented with acute heart failure and incessant wide complex tachycardia resembling an outflow tract ventricular tachycardia. Meticulous analysis of the electrocardiograms established the diagnosis of pre-excitation with prolonged atrio-ventricular (A-V) conduction over a decrementally conducting accessory A-V pathway. "Linking" between the accessory A-V pathway and normal A-V conduction system resulted in sustained maximal pre-excitation as well as periodic transition to normal A-V conduction without appreciable change in heart rate. Successful radiofrequency ablation of this unusual accessory A-V pathway was performed at the aortic-mitral junction. This ameliorated the mechanical dysynchrony, allowed discontinuation of hemodynamic/inotropic support, and resulted in sustained symptomatic improvement.

Clinico-histopathological correlation of symptomatic left main coronary artery electrocardiographic ischemia pattern in a young child with hypertrophic cardiomyopathy.

The specific electrocardiographic (ECG) pattern of left main coronary artery ischemia is exceptionally rare in children and under recognized. Occasional reports are bereft of a detailed mechanistic ECG description and limited to dissection, spasm, or anomalous origin of the left main coronary artery. An association with pediatric hypertrophic cardiomyopathy (HCM) is hitherto unreported. We furbish a detailed electrocardiographic description of this entity in the unusual setting of a 4-year-old child with HCM with a restrictive phenotype and exertional symptoms consistent with myocardial ischemia. Heart transplant was performed for this rare indication. Histopathology of the explanted heart in particular revealed left main coronary artery narrowing and provided us with a unique window of opportunity to correlate with clinical findings. The pathophysiology was also likely exacerbated by diffuse sub endocardial ischemia in the milieu of left ventricular hypertrophy with elevated end diastolic pressures. We anticipate that this illustrative case will help contextualize this as well as pediatric scenarios in which the 'left main ischemia' ECG pattern can be encountered and foster an accurate electrocardiographic recognition of this entity in children.

Device-detected nonsustained ventricular tachycardia in adult congenital heart disease without tetralogy of fallot.

OBJECTIVES: To evaluate any association between non-sustained ventricular tachycardia (NSVT) detected by intra-cardiac device and clinical outcomes in repaired adult congenital heart disease (ACHD) without tetralogy of Fallot (TOF). BACKGROUND: NSVT portends a higher risk of serious ventricular tachyarrhythmia in TOF. However its clinical significance when incidentally detected by implantable cardiac device is not well elucidated in non-TOF ACHD cohort. METHODS: We performed a single center, retrospective, longitudinal follow-up study in repaired ACHD (≥18 years) patients without TOF who hosted a pacemaker or automatic implantable cardiac defibrillator (AICD). The cohort was divided based on presence/absence of device detected NSVT. The primary end-point was a composite of sustained ventricular tachycardia (VT), ventricular fibrillation (VF), or sudden cardiac death (SCD). RESULTS: One hundred fifty eight patients (male 56.3%, median [IQR] age of 35 [28-43] years at last follow-up] with longitudinal post-implant follow-up duration of 8 (5-12) years were included. NSVT was detected in 52 (33%) patients. The primary composite end-point was more frequent in NSVT group [11.5% vs. 2.8%; p = .04]. Patients with NSVT were (i) older at the time of initial implant (age 25 vs. 18 years, p = .011) and more frequently demonstrated (ii) systemic ventricular dysfunction (44% vs. 26%; p = .015), as well as (iii) history of ventriculotomy (38% vs. 21%; p = .017). CONCLUSIONS: In our repaired ACHD cohort, we noted a significant association between device-detected-NSVT and the primary composite end-point of sustained VT/VF or SCD. Systemic ventricular dysfunction and history of ventriculotomy were more frequent in the NSVT group and likely constituted the clinical milieu.