Left Ventricular Myocardial Septal Pacing in Close Proximity to LBB Does Not Prolong the Duration of the Left Ventricular Lateral Wall Depolarization Compared to LBB Pacing

Background: Three different ventricular capture types are observed during left bundle branch pacing (LBBp). They are selective LBB pacing (sLBBp), non-selective LBB pacing (nsLBBp), and myocardial left septal pacing transiting from nsLBBp while decreasing the pacing output (LVSP). Study aimed to compare differences in ventricular depolarization between these captures using ultra-high-frequency electrocardiography (UHF-ECG).Methods: Using decremental pacing voltage output, we identified and studied nsLBBp, sLBBp, and LVSP in patients with bradycardia. Timing of ventricular activations in precordial leads was displayed using UHF-ECGs, and electrical dyssynchrony (e-DYS) was calculated as the difference between the first and last activation. The durations of local depolarizations (Vd) were determined as the width of the UHF-QRS complex at 50% of its amplitude.Results: In 57 consecutive patients, data were collected during nsLBBp (n = 57), LVSP (n = 34), and sLBBp (n = 23). Interventricular dyssynchrony (e-DYS) was significantly lower during LVSP −16 ms (−21; −11), than nsLBBp −24 ms (−28; −20) and sLBBp −31 ms (−36; −25). LVSP had the same V1d-V8d as nsLBBp and sLBBp except for V3d, which during LVSP was shorter than sLBBp; the mean difference −9 ms (−16; −1), p = 0.01. LVSP caused less interventricular dyssynchrony and the same or better local depolarization durations than nsLBBp and sLBBp irrespective of QRS morphology during spontaneous rhythm or paced QRS axis.Conclusions: In patients with bradycardia, LVSP in close proximity to LBB resulted in better interventricular synchrony than nsLBBp and sLBBp and did not significantly prolong depolarization of the left ventricular lateral wall.

Understanding Pacemaker-Induced Cardiomyopathy Incidence and Predictors in Patients with Right Ventricular Pacing: A Systematic Review

This study aimed to figure out the incidence and predictors of pacemaker-induced cardiomyopathy (PICM) in patients with right ventricular (RV) pacing. We systematically searched in PubMed on March 18, 2020, for English language abstract and full-article journals, using the following criteria: pacemaker induced cardiomyopathy AND right ventricular AND pacemaker AND patients AND human NOT implantable cardioverter defibrillator NOT ICD NOT animal. Four studies were included in this review after filtering 35 studies through year of publication and abstract selection. The average PICM incidence from 1,365 patients included from the four studies was 10.7 to 13.7%. One study stated that preimplantation left ventricular ejection fraction (LVEF) was the predictor for the development of PICM. Three studies mentioned that RV pacing burden was the predictor for the development of PICM. However, the percentage differ in three studies: ≥20, >40, and 60%. In addition, one of the studies also included interventricular dyssynchrony as another predictor. The incidence of PICM in patients with RV pacing ranged from 10.7 to 13.7%. Preimplantation LVEF, interventricular dyssynchrony, and burden of RV pacing are reported as the predictors for the development of PICM in patients with RV pacing.

Influence of selective stimulation of the right ventricle on electric and mechanical myocardial disynchrony

Relevance. Prolonged apical stimulation of the right ventricle can lead to the development of interventricular and intraventricular dyssynchrony. Selective (alternative) stimulation of various parts of the interventricular septum due to a more physiological propagation of the excitation wave makes it possible to prevent the deterioration of the mechanical function of the myocardium associated with constant pacing.Purpose. To study the dynamics of indicators of electrical and mechanical ventricular dyssynchrony in the traditional (apical) and alternative with the installation of a right ventricular electrode in the interventricular septum or the outlet tract of the right ventricle in patients with constant pacing in the early and late postoperative period.Materials and methods. Were included 73 patients (mean age 61.0 ± 2.5 years) with indications for continuous cardiac pacing without signs of heart failure above 2 FC according to NYHA and previous Q-forming myocardial infarction. Patients of group 1 (n = 39) were implanted with a pacing ventricular electrode in the middle section of the interventricular septum (subgroup 1A, n = 25) or in the outflow tract of the right ventricle (subgroup 1B, n = 14). The control group 2 included 34 patients with electrode implantation in the apex of the right ventricle.Results. The time of pre-ejection from the right and left ventricles before and after implantation did not differ in group 1 and significantly differed in group 2 (25 ± 3 ms and 50 ± 6 ms, p < 0.05). There was no significant difference in the parameters of ventricular remodeling between the groups within 2 years, but there was a tendency towards a lower value of the left ventricular ejection fraction (59 ± 6 % and 50 ± 2 %, p = 0.05) and a higher frequency of mitral regurgitation 2 degree and higher in patients in the apical stimulation group. Within the group of alternative stimulation, after 2 years of follow-up, there was a tendency towards a smaller value of the delay time of systolic contraction between the basal segments of the free wall of the right ventricle and the interventricular septum during stimulation of the outflow tract compared with stimulation of the middle part of the interventricular septum (30 ± 8 ms and 38 ± 10 ms , p = 0.05).Conclusions. Alternative stimulation of the right ventricle compared with the apical is characterized by a lower degree of interventricular dyssynchrony both immediately after surgery and in the long-term period. New echocardiographic technologies, including tissue myocardial Doppler ultrasonography, make it possible to quantify the indicators of systolic and diastolic myocardial function and various parameters of dyssynchrony.Conclusion. To assess the physiology, clinical efficacy and safety of the new method of stimulating the interventricular septum, a more thorough study of the severity of intra- and interventricular dyssynchrony, indicators of global and regional systolic and diastolic function of the left and right ventricles is necessary.

Bi-Ventricular Myocardial Performance in Heart Failure: A New Approach to Evaluate Interventricular Dyssynchrony

Aims: Patients with heart failure (HF) exhibit ventricular dyssynchrony with negative effects on ventricular systolic and diastolic performance and poor prognosis. There is no consensus about the best approach for estimating the dyssynchrony and for selecting candidates for resynchronization therapy (CRT). We sought to evaluate whether Myocardial Performance Index (MPI), calculated as differences between left and right ventricle (LV, RV), ∆MPI, represents a marker of interventricular dyssynchrony. Methods: The study included 40 patients (22 males, 18 females, mean age 71±13) with NYHA functional class II-III, chronic heart failure (77% ischaemic), in optimal drug therapy for at least three months. All patients underwent a complete two-dimensional and Tissue Doppler Echocardiography (TDE), including an assessment of MPI in both ventricles. Results: Significant correlations were found between ∆MPI and QRS (r = 0.41, p < 0.001), with NYHA (r = 0.66, p < 0.001), with SPWMD (r = 0.32, p < 0.05), with LV ejection fraction (r = -0.32, p < 0.05), with Spv wave at the septal site of LV (r = -0.32, p < 0.05), and with IVMD (r = 0.44, p < 0.001). Ten patients have been re-evaluated six months after CRT implantation, and ∆MPI significantly correlated with the difference between basal LVEF and six months after CRT implantation (r = 0.43, p < 0.04). Conclusion: The ∆MPI could represent an integrative marker of interventricular dyssynchrony and could be considered as a new parameter in the patient selection process to be undergone CRT.