136 Blood vortices analysis in children with Wolff–Parkinson–White syndrome

Aims Wolff–Parkinson–White syndrome (WPW) is a clinical condition characterized by pre-excitation on electrocardiogram (ECG) and symptoms of arrhythmias. It has been described that premature ventricular activation induces septal wall motion abnormalities and ventricular dyssynchrony, causing detrimental effects on cardiac performance. The new speckle-tracking-based technique, blood speckle imaging (BSI), has been previously used to evaluate blood flow characteristics in normal and dysfunctional hearts in patients with normal atrio-ventricular (AV) conduction. We aimed to study the features of left ventricle blood vortices in patients with WPW and short AV conduction by using BSI. Methods and results Nineteen paediatric patients (age 7 ± 2.9 years) were included in the study: 13 patients with manifest WPW (WPW group) and 6 age and sex -matched controls with normal AV conduction (CTR group). A complete echocardiographic evaluation with 2D, color Doppler, and BSI was performed in all the included patients. BSI was recorded in apical 3-chamber view with a 6S-D probe. Vortices characteristics were analysed during the filling phase of the left ventricle. We focused on the anterior vortex generated by the mitral valve, which persisted longer during the cardiac cycle and is assumed to contribute to optimizing cardiac function. For each child in the WPW group, Arruda criteria were used to esteem accessory pathway localization from a 12-lead surface ECG. All patients in the WPW group manifested the accessory pathway in the septal region. All patients in the CTR group presented one major anterior vortex along the septal wall during the filling phase (Figure A), while in the WPW group, 10 patients out of 13 (P = 0.009) lacked this main anterior vortex, showing instead fragmented vortices (Figure B). Interestingly, the main differences in blood vortices pattern were showed in the last part of filling phase, when blood flow could be affected by premature activation of the septal wall. There were no differences in terms of left ventricle function (WPWg 59.8 ± 4.02% vs. CTRg 59.0 ± 2.5%, P = 0.6) and global longitudinal strain (WPWg −18.6 ± 1.0% vs. CTRg −19.6 ± 3.1%, P = 0.5) between the two groups. 136 Figure A and B Conclusions In our preliminary study, patients with WPW showed a fragmented pattern of diastolic blood vortices that adapted to septal dyssynchrony. We speculate this fragmentation may contribute to impair the performance of the left ventricle.

Atrioventricular-block necessitating ventricular pacing after tricuspid valve surgery in patients with a systemic right ventricle: long term follow-up

Background Patients with transposition of the great arteries (TGA) after atrial switch or congenitally corrected TGA (ccTGA) are prone to systemic right ventricular (sRV) failure. Atrioventricular (AV)-conduction disturbances and tricuspid regurgitation aggravate the course of sRV dysfunction. Timely tricuspid valve (TV) surgery stabilizes sRV function. However, TV surgery is an independent risk for AV-block and ventricular pacing in non-congenital cardiothoracic surgery patients. Chronic subpulmonary ventricular pacing-induced dyssynchrony further contributes to sRV failure, potentially reducing the beneficial effects of the tricuspid valve surgery. Purpose The aim of this study is to explore the incidence, timing and functional consequences of AV-conduction block requiring ventricular pacing after TV surgery in sRV patients. Methods Consecutive adolescent and adult patients with a sRV who underwent TV surgery in the period 1989–2020 and follow-up at our tertiary care center were included in this observational cohort study. Patients who were <10 years of age at the time of operation and/or died in perioperative, in-hospital, setting were excluded from analysis (n=5). Demographic and clinical data was collected from the patient records. Results Data of 28 patients (54% female, 57% ccTGA) was analysed (Figure). The mean age at surgery was 38±13 years, 5 patients (18%) received chronic ventricular pacing preoperatively. Mean follow-up was 9.7±6.8 years, during which 7 patients (25%) died and 3 (11%) underwent ventricular assist device implantation (VAD). Two patients died awaiting VAD/HTx, one patient died awaiting CRT upgrade. Seven (25%) patients underwent a re-operation, of which 3 (11%) TV replacement, 3 (11%) VAD and 1 (4%) pulmonary valve replacement. Of the 23 patients at risk of developing AV-block, 11 (48%) developed an indication for chronic ventricular pacing, of which 6 within 24 months postoperatively (4 before hospital discharge). Of the 21 patients with a device, 7 (25%) had successful resynchronization therapy (2 before TV surgery). Patients with chronic ventricular pacing had a wider QRS-duration (mean 121 ms vs 194 ms in those without pacing, p<0.001) and 43% had a severely reduced sRV function (vs 36% in those without pacing) at latest follow-up. Conclusions Patients with a failing sRV who undergo TV surgery are prone to AV-conduction abnormalities with 48% of this group developing an indication for chronic ventricular pacing during follow-up. Pacing-induced dyssynchrony can further contribute to sRV dysfunction. Implantation of an epicardial sRV lead at the time of TV surgery for future CRT may be considered to attenuate the detrimental effects of subpulmonary ventricular pacing in this heart failure prone patient group with complex anatomy, limiting transvenous possibilities. FUNDunding Acknowledgement Type of funding sources: None.

Prevalence and clinical impact of atrioventricular conduction disease in patients with idiopathic pulmonary arterial hypertension

Background Although bradycardia-related sudden death is common in patients with idiopathic pulmonary arterial hypertension (IPAH), the prevalence and prognostic significance of atrioventricular (AV) conduction disease in this patient group is not well-established. Objectives – Determine the prevalence of AV conduction disorders in patients with IPAH – Investigate the relationship between AV block and functional outcomes and mortality. Method 12-lead electrocardiograms (ECGs) of patients with IPAH were analysed. Patients were categorised according to the presence or absence of AV block. Demographic, pulmonary haemodynamic, cardiac structural characteristics and expression of genes associated with cardiac conduction were compared and functional and mortality outcomes analysed between groups. Student's t-tests and χ2 tests were used to compare data. Survival was estimated using Kaplan-Meier analyses. Initial exploratory covariates were included in a univariate analysis and those terms with P-value of <0.1 were then used to generate a Cox proportional-hazards multivariate model. Results 135 IPAH patients (mean age 55±16 years, 28.1% male) were eligible for analysis. Median follow up was 9 years (interquartile range 4–14 years). AV block was seen in 34.8% of patients with IPAH compared to 10.8% of matched comparators (p<0.001), drawn from patients attending hospital for non-PAH related reasons. IPAH patients with conduction disease were more likely to be older (59±16 vs 53±17 years, p=0.038). AV block was associated with more severe right ventricular (RV) basal dilatation (5.1±1.0 vs 4.3±0.7cm, p=0.013) and worse RV function (fractional area change 26±9% vs 31±9%, p=0.14). Pulmonary haemodynamics, right atrial size and resting and exertional oxygen saturations were not significantly different. Expression of HCN1, HCN2, SCN1B, SCN5A, CAV1, and KCN2 genes in peripheral blood from a subcohort was similar between those with and without AV block. Lower 6 minute walk distances (344±153 vs 408±140m, p=0.035) and worse CAMPHOR scores across all 3 domains were seen in those with AV block (figure 1), and mortality was significantly higher (36.2 vs 13.6%, p=0.002) (figure 2). On multivariate analysis the presence of bundle branch block (BBB) was independently associated with a 2.1-fold increased risk of death (95% CI 1.89–4.85, p=0.045). Conclusions AV conduction disorders are more prevalent in IPAH than the general population, and are associated with worse prognosis and functional status. Prospective study is required to validate this finding. In our cohort AV block could not be explained by hypoxia, differences in pulmonary haemodynamics nor, in a small subgroup, by differential expression of specific transmembrane ion channels implicated in cardiac conduction. More detailed investigation into causal mechanisms of AV block in IPAH could establish whether improved prognosis could be achieved by treatment of AV block. FUNDunding Acknowledgement Type of funding sources: None. Figure 1 Figure 2

A rare and reversible cause of third-degree atrioventricular block: a case report

Background Cardiac involvement of Lyme disease (LD) typically results in atrioventricular (AV) conduction disturbance, mainly third-degree AV block. Case summary A 54-year-old patient presented to our emergency department due to recurrent syncope. Third-degree AV block with a ventricular escape rhythm (33 b.p.m.) was identified as the underlying rhythm. Transthoracic echocardiography (TTE) was normal. To rule out common reversible causes of complete AV block, a screening test for Lyme borreliosis was carried out. Elevated levels for borrelia IgG/IgM were found and confirmed by western blot analysis. Lyme carditis (LC) was postulated as the most likely cause of the third-degree AV block given the young age of the patient. Initiation of antibiotic therapy with ceftriaxone resulted in a gradual normalization of the AV conduction with stable first-degree AV block on Day 6 of therapy. The patient was changed on oral antibiotics (doxycycline) and discharged without a pacemaker. After 3 months, the AV conduction recovered to normal. Discussion Lyme carditis should always be considered, particularly in younger patients with new-onset AV block and without evidence of structural heart disease. Atrioventricular block recovers in the majority of cases after appropriate antibiotic treatment.

Prospective evaluation of the learning curve and electrical characteristics of left bundle branch area pacing

Background Left bundle branch area pacing (LBBAP) has recently been introduced as a physiological pacing technique with a synchronous ventricular activation. Objective To prospectively evaluate the feasibility and learning curve, as well as the electrical characteristics of LBBAP. Methods In 80 consecutive LBBAP pacemaker patients, ECG characteristics during intrinsic rhythm, RV septum pacing (RVSP) and LBBAP were evaluated. From the ECG's QRS duration and LVAT (stimulus to V6 R-wave peak time, RWPT) were measured. Also, the left bundle branch potential (LBBpot) to V6 RWPT interval was measured and compared to the LVAT. After conversion of the ECG into VCG (Kors conversion matrix), QRS area, as measurement for electrical dyssynchrony, was calculated. Results Permanent lead implantation was successful in 77/80 patients (96%) undergoing an attempt at LBBAP. LBBAP lead implantation time as well as fluoroscopy time were significantly shorter during last 25% of implantation compared to first 25% of implantations (17±5 min vs. 33±16 min and 12±7 min vs. 21±13 min, respectively, panel A and B). LBB capture was obtained in 54/80 patients (68%). In 36/45 patients (80%) with intact AV conduction and narrow QRS an LBBpot was present. The mean interval between the LBBpot and the onset of QRS was 22±6 ms. In the patients with narrow QRS (n=45), QRS duration increased significantly during both RVSP (139±24 ms) and LBBAP (123±21 ms), compared to intrinsic rhythm (95±13 ms). QRS area on the other hand, increased during both RVSP (73±20 μVs) but decreased during LBBAP (41±15 μVs), to values close to intrinsic rhythm (32±16 μVs, panel C). For all patients, QRS area was significantly lower in patients with LBB capture compared to patients without capture (43±18 μVs vs 54±21 μVs, respectively). In patients with LBB capture (n=54), LVAT was significantly shorter compared to patients without LBB capture (75±14 vs. 88±9 ms, respectively). In the patients with LBB capture, there was a significant correlation between the LBBpot – V6 RWPT and S – V6 RWPT intervals (Pearson correlation 0.739, P<0.001). Conclusion LBBAP is a safe and feasible technique, with a clear learning curve that seems obtained after ± 40–60 implantations. LBB capture is obtained in two-thirds of patients. Although QRS duration remains prolonged, LBBAP largely restores ventricular electrical synchrony to values close to intrinsic (narrow QRS) rhythm. FUNDunding Acknowledgement Type of funding sources: None.

Effects of Adaptive Cardiac Resynchronization Therapy With Left-Bundle-Branch Area Pacing and Coronary Sinus Pacing

Adaptive cardiac resynchronization therapy (aCRT) is associated with improved clinical outcomes. Left bundle branch area pacing (LBBAP) has shown encouraging results as an alternative option for CRT. In this study, we observed the clinical and echocardiographic outcome of LBB-optimized aCRT in combination with synchronized LV pacing (LOT-aCRT) in heart failure patients with reduced ejection fraction and LBBB. Heart failure patients with preserved AV conduction and LBBB morphology, who underwent aCRT from February 1, 2019, to September 30, 2020 were included. The eligible patients with or without LBBAP were divided into LOT-aCRT group or BV-CRT group. In LOT-aCRT group, the CS lead was connected to the pace-sensing portion of the RV port, and the LBBAP lead was connected to the LV port. Seventeen patients were enrolled in this study (8 cases in LOT-aCRT group, 9 cases in BV-CRT group). Patients were matched for ischemic cardiomyopathy (ICM) at baseline (5 cases vs. 4 cases). QRS duration (QRSd) via BVP was narrowed from 158.0 ± 13.0 ms at baseline to 132.0 ± 4.5 ms in LOT-aCRT group (P=0.019), and further narrowed to 123.0 ± 5.7 ms (P < 0.01) via LBBAP. However, LOT-aCRT resulted in further reduction of the QRSd (121.0 ± 3.8 ms), but no statistical significance (P > 0.05). In BV-CRT group, BVP resulted in significant reduction of the QRSd from 176.7 ±19.7 ms at baseline to 143.3 ±8.2 ms (P=0.011). However, compared with LOT-aCRT, BVP has no any advantage in reducing QRSd (P > 0.05). During follow-up, patients in LOT-aCRT group showed significant improvement in LVEF and NT-proBNP levels (P < 0.01), while patients in BV-CRT group showed non-significant changes in these parameters (P >0.05). The study demonstrates that LOT-aCRT is clinically feasible in patients with systolic HF and LBBB. LOT-aCRT was associated with significant narrowing of the QRSd and improvement in LV function, especially in patients with ICM.

Bradyarrhythmic Cardiac Arrest—A Rare Manifestation of Fexofenadine Cardiotoxicity

A 66-year-old diabetic, hypertensive, and hypothyroid female presented in the emergency department with cardiac arrest, for which cardiopulmonary resuscitation was immediately initiated. She had been on oral fexofenadine for 36 h prior to the event. Post successful resuscitation, her cardiac rhythm showed high-grade atrioventricular block. Patient was treated with mechanical ventilatory support and temporary transvenous pacing. No treatable cause could be identified, and she recovered completely following fexofenadine discontinuation, without need for a permanent pacemaker. She has remained asymptomatic during 1 year of follow-up with no documented arrhythmias. An electrophysiological study at 6 months revealed prolonged HV interval (70 ms) with 1:1 AV conduction and no inducible arrhythmias. This is probably the first reported case of fexofenadine-induced cardiac arrest in a patient without previous history of heart disease.

Left Ventricular Myocardial Noncompaction with Advanced Atrioventricular Conduction Disorder and Ventricular Arrhythmias in a Young Patient: Role of MIB1 Gene

Left ventricular noncompaction (LVNC) is a structural abnormality of the left ventricle, usually described as an isolated condition, or sometimes associated with other structural cardiac diseases. LVNC is generally asymptomatic, although it may present conduction disorders, arrhythmias, and heart failure. Here, we present the case of a patient who came to our attention with a severe LVNC phenotype associated with advanced AV conduction disorder, and supraventricular and ventricular arrhythmias at young age, in which a novel MIB1, likely pathogenic, variation has been identified.

Fusion Pacing with Biventricular, Left Ventricular-only and Multipoint Pacing in Cardiac Resynchronisation Therapy: Latest Evidence and Strategies for Use

Despite advances in the field of cardiac resynchronisation therapy (CRT), response rates and durability of therapy remain relatively static. Optimising device timing intervals may be the most common modifiable factor influencing CRT efficacy after implantation. This review addresses the concept of fusion pacing as a method for improving patient outcomes with CRT. Fusion pacing describes the delivery of CRT pacing with a programming strategy to preserve intrinsic atrioventricular (AV) conduction and ventricular activation via the right bundle branch. Several methods have been assessed to achieve fusion pacing. QRS complex duration (QRSd) shortening with CRT is associated with improved clinical response. Dynamic algorithm-based optimisation targeting narrowest QRSd in patients with intact AV conduction has shown promise in people with heart failure with left bundle branch block. Individualised dynamic programming achieving fusion may achieve the greatest magnitude of electrical synchrony, measured by QRSd narrowing.

An electrographic AV optimization for the maximum integrative atrioventricular and ventricular resynchronization in CRT

Background Atrioventricular (AV) delay could affect AV and ventricular synchrony in cardiac resynchronization therapy (CRT). Strategies to optimize AV delay according to optimal AV synchrony (AVopt-AV) or ventricular synchrony (AVopt-V) would potentially be discordant. This study aimed to explore a new AV delay optimization algorithm guided by electrograms to obtain the maximum integrative effects of AV and ventricular resynchronization (opt-AV). Methods Forty-nine patients with CRT were enrolled. AVopt-AV was measured through the Ritter method. AVopt-V was obtained by yielding the narrowest QRS. The opt-AV was considered to be AVopt-AV or AVopt-V when their difference was < 20 ms, and to be the AV delay with the maximal aortic velocity–time integral between AVopt-AV and AVopt-V when their difference was > 20 ms. Results The results showed that sensing/pacing AVopt-AV (SAVopt-AV/PAVopt-AV) were correlated with atrial activation time (Pend-As/Pend-Ap) (P < 0.05). Sensing/pacing AVopt-V (SAVopt-V/PAVopt-V) was correlated with the intrinsic AV conduction time (As-Vs/Ap-Vs) (P < 0.01). The percentages of patients with more than 20 ms differences between SAVopt-AV/PAVopt-AV and SAVopt-V/PAVopt-V were 62.9% and 57.1%, respectively. Among them, opt-AV was linearly correlated with SAVopt-AV/PAVopt-AV and SAVopt-V/PAVopt-V. The sensing opt-AV (opt-SAV) = 0.1 × SAVopt-AV + 0.4 × SAVopt-V + 70 ms (R2 = 0.665, P < 0.01) and the pacing opt-AV (opt-PAV) = 0.25 × PAVopt-AV + 0.5 × PAVopt-V + 30 ms (R2 = 0.560, P < 0.01). Conclusion The SAVopt-AV/PAVopt-AV and SAVopt-V/PAVopt-V were correlated with the atrial activation time and the intrinsic AV conduction interval respectively. Almost half of the patients had a > 20 ms difference between SAVopt-AV/PAVopt-AV and SAVopt-V/PAVopt-V. The opt-AV could be estimated based on electrogram parameters.