Surgical myectomy, dual-chamber pacing and alcohol septal ablation are equally effective in reducing obstruction in case of correct indications. Dual-chamber pacing is indicated in functional reversible states characterized by excitation delay. Alcohol septal ablation is preferable in cases with midventricular obstruction and appropriate coronary anatomy. Surgical methods are indicated in anatomical irreversible changes and remain the gold standard for obstructive hypertrophic cardiomyopathy treatment.
Background. Implementation of conduction system permanent pacing methods in patients with cardiac bradyarrhythmias allows to maintain the physiological sequence of excitation and contraction of the ventricles and to avoid the development of heart failure due to electrical and mechanical dyssynchrony in patients with high rates of ventricular pacing. Case description. A 61-year-old female patient was examined and treated at the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine from January 25 to January 27, 2022 at the department of surgical treatment of complex cardiac arrhythmias with a diagnosis of proximal complete atrioventricular block. A two-chamber pacemaker (Vitatron Q50A2) with a ventricular lead to stimulate the His bundle region (Medtronic 3830, 69 cm) was implanted to the patient with a special delivery system (C315HIS). At an X-ray operating room, 12 ECG leads from the electrophysiological station LabSystem Pro (Bard, USA) were connected to the patient to analyze the criteria for capturing the conduction system on stimulation during ventricular lead placement, and a diagnostic quadripolar electrode was inserted into the right ventricle to record the potential of the His bundle as an X-ray reference point. During placement of the ventricular lead in the area of the His bundle due to high pacing thresholds the decision was made to implement an alternative method of conduction system pacing – left bundle branch pacing through the interventricular septum. After gradual passage of the electrode through the septum, capture of the conduction system of the heart was achieved, although no clear potential of the left bundle was registered. The interval from stimulus to peak R wave in lead V6 was 68 ms, and the interval from stimulus to peak R wave in lead V1 was 110 ms. The difference between intervals was 42 ms, which indicated the criteria of nonselective capture of the left bundle branch, with stimulation thresholds below 1 V at a pulse length of 0.5 ms. In the postoperative period, the patient was evaluated for global longitudinal deformity of the left ventricle on constant ventricular stimulation, which was carried out according to standard methods using speckle-tracking echocardiography; no signs of dyssynchrony were found. Also, the location of the endocardial electrode in the middle segments of the interventricular septum on the right ventricular side was visualized and confirmed by performing B-mode transthoracic echocardiography with subcostal access. Conclusions. Left bundle branch pacing, like His bundle pacing, maintains electrical and mechanical synchrony of the left ventricle at lower pacing thresholds, greater amplitude of the sensitivity signal and lower risks of lead dislocation.
Right ventricular pacing may impair left ventricular systolic function in patients with reduced left ventricular ejection fraction (LVEF). The aim. To determine the frequency of pacing-induced cardiomyopathy (PICM) in patients with permanent right ventricular pacing (at least 90%) and preserved LVEF (≥50%). To determine the risk factors for the occurrence of PICM. Materials and methods. The study included 34 patients with indications for permanent ventricular pacing in whom pacemaker was implanted from 2012 to 2022 (mean follow-up period 44.97 ± 28.45 months). PICM was defined as a decrease in LVEF <45% during follow-up regardless of clinical manifestations. Risk factors for PICM were determined through univariate and multivariate regression analysis. Results. The incidence of PICM in this study was 26% during the mean observation period of 44.9 ± 28.4 months. The mean time to the onset of PICM was 29 months in 5 out of 9 patients (55%), the time from implantation to diagnosis of PICM was less than a year. The mean LVEF and end-diastolic volume index at the time of follow-up differed significantly in the groups with and without PICM: 38.6 ± 5.9% vs. 53.5 ± 5.7% (p<0.001) and 97.9 ± 20.75 ml/m2 vs. 60.9 ± 19.32 ml/m2 (p<0.001), respectively. In the PICM group intraventricular asynchrony was 261.1 ± 61 ms vs. 146.1 ± 62.8 ms (p<0.001), interventricular asynchrony 91 ± 36.4 ms vs. 54.2 ± 22.2 ms (p = 0.014), the number of segments with reduced deformation 8.1 ± 2.6 vs. 3.91 ± 2.3 (p<0.001), global longitudinal strain –9.7 ± 2.6 % vs. –14.9 ± 3.4 % (p<0.001). At the time of the follow-up examination, the signal of sensitivity on ventricular lead in the PICM group was significantly reduced compared to patients without PICM (6.26 ± 4.02 mV vs. 11.56 ± 3.86 mV, p = 0.045). Paced QRS width in the PICM group was significantly larger (163 ± 22.7 ms vs. 150.8 ± 14.5 ms) and there were more patients with rate-adapted cardiac pacing in the PICM group: 4 (40%) vs. 2 (8%) (p = 0.0428). In multivariate regression analysis, a wider paced QRS (hazard ratio 1.09 for every 1 ms increment in QRS width, 95% confidence interval 1.01-1.17, p = 0.025) was an independent predictor of PICM. In two patients from PICM group, upgrade of pacemaker system to biventricular pacing was performed with an improvement in the left ventricular contractility: in one patient from 37% to 44%, in another from 34% to 51% in one and two month, respectively. Conclusions. Cardiomyopathy due to right ventricular pacing tends to occur instantaneously in the first years after pacemaker implantation, rather than slowly progressing over time. A wider paced QRS complex is an independent predictor of PICM. Biventricular pacing effectively eliminates the consequences of non-physiological right ventricular pacing, improves left ventricular systolic function.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.