Cardiac pacing in patients with hypertrophic obstructive cardiomyopathy

Abstract

[first paragraph of article]About one-third of patients with hypertrophic cardiomyopathy (HCM) have resting left ventricular outflow tract obstruction (LVOTO). The presence of LVOTO in HCM facilitates the progression of heart failure and increases the risk of death. LVOTO is defined as a peak instantaneous Doppler LV outflow tract gradient ≥30 mmHg, but the threshold for invasive treatment is usually considered to be ≥50 mm Hg.

Hypertensive hypertrophic obstructive cardiomyopathy crisis resolved with transvenous pacing guided by bedside echocardiography

“…Acute preload or afterload reduction increases the severity of LVOT obstruction and compromises hemodynamics 1–3 . This was further exacerbated by initiation of pharmacologic agents with positive inotropic effect 1,4 …”

“…[1][2][3] This was further exacerbated by initiation of pharmacologic agents with positive inotropic effect. 1,4 Systolic anterior motion of the mitral valve worsens LVOT obstruction and results in subsequent dynamic mitral regurgitation. Slower heart rates allow for increased filling of the left ventricle and therefore decrease the cardiac outflow obstruction; however, with more time in systole for flow across the mitral valve, mitral regurgitation worsens.…”

Energy loss by right ventricular pacing: Patients with versus without hypertrophic cardiomyopathy

“…RVa pacing enlarged and normalized the vortex during the IVC period in the HCM group (Figure 2), suggesting that RVa pacing improved the LV flow patterns and reduced the EL. Historically, RVa pacing has played an important role in the reduction of an LVOT obstruction 34 . A reduced contraction of the LV, paradoxical septal motion with a delayed septal thickening, limitation of an abnormal mitral valve motion, interaction with LV filling, and ventricular remodeling are considered the mechanisms of the reduction in the LVOT obstruction by RVa pacing 6,35 .…”

“…Historically, RVa pacing has played an important role in the reduction of an LVOT obstruction. 34 compression in patients with HCM and hypertensive heart disease. 36 In such patients, an increased end-systolic volume may preserve the cardiac cavity during diastole, creating large vortices.…”

Post-operative management of hypertrophic obstructive cardiomyopathy

“…10,13 Procedural therapies to alleviate LVOTO in drug refractory HOCM include either sequential dual chamber pacing with short atrioventricular delay or surgical reduction therapies such as septal myectomy or septal alcohol ablation. 14,15 Surgical myectomy has been performed since the 1950s with efficacy rates exceeding 90%. 10 It is indicated in patients with (a) gradient >50 mmHg at rest or with provocation, (b) persistent symptoms despite medications or (c) syncope due to LVOT obstruction (Figure 2).…”