A New Paradigm for Physiologic Ventricular Pacing

Abstract

Clinical trials in patients with pacemakers for sinus node dysfunction or atrioventricular block (AVB) and implantable cardioverter-defibrillators provide increasing evidence showing that desynchronization of ventricular electrical activation and contraction, induced by conventional right ventricular apex (RVA) pacing, is a serious threat for long-term cardiac morbidity and mortality. The risk of heart failure is increased even in hearts with initially normal pump function and in case of part-time ventricular pacing. These epidemiologic data fit with knowledge from decades of pathophysiological research, indicating that right ventricular (RV) pacing creates abnormal contraction, reduced pump function, hypertrophy, and ultrastructural abnormalities. This paper presents a new paradigm that aims to tailor ventricular pacing to the individual patient to achieve a way of pacing that is as physiologic as possible. In patients without AVB and no intraventricular conduction abnormalities, ventricular pacing should be avoided as much as possible, using atrial-based pacing. In patients with AVB, alternate single-site RV or left ventricular pacing or biventricular pacing may be superior to RVA pacing. Efforts to optimize the pacing mode or site should be greater in patients with a longer expected duration of pacing, poorer cardiac function, and larger mechanical asynchrony. Awareness of the problem of desynchronization should also lead to more regular monitoring of cardiac pump function and mechanical asynchrony in any patient with ventricular pacing.

TUGENDHAT: a pilot randomized study on effects of biventricular pacing in patients with bradycardia pacing indication and normal systolic function on heart failure, atrial fibrillation and quality of life (results of 12 month follow-up)

“…The adverse cardiac remodelling might be prevented by BiV pacing probably after a longer period of follow-up. Despite the use of RV apical pacing, development of HF, increased morbidity and mortality have been recognized in the past 10 years with the publication of the results of various large trials of pacemakers and implantable cardioverterdefi brillators (13,14,15). The adverse clinical events seem to be related to a high cumulative percentage of RV apical pacing (16).…”

Current possibilities of permanent pacing for prevention of atrial fibrillation and heart failure progression

“…Традиционно эндокардиальный электрод им-плантируют в область верхушки правого желудочка (ПЖ), учитывая удобство и быстроту позиционирования, ста-бильность положения электрода [21]. Крупные рандоми-зированные исследования предоставили важную информа-цию об оптимальных режимах стимуляции, а также показа-ли, что правожелудочковая апикальная стимуляция может привести к прогрессированию хронической сердечной не-достаточности (ХСН), развитию наджелудочковых тахиа-ритмий (НЖТ) и увеличению смертности [10,22,27].…”

“…Стимуляция из верхушки ПЖ нарушает электрическую и механиче-скую систолу желудочков вследствие изменения не толь-ко нормальной последовательности, но и скорости про-ведения импульса, так как распространение волны воз-буждения через миокард происходит гораздо медленнее, чем через систему Гиса-Пуркинье [21]. Данные измене-ния схожи с патологическими процессами, которые раз-виваются при блокаде левой ножки пучка Гиса [26].…”

Avaliação da estimulação ventricular direita crônica em crianças e adultos jovens com bloqueio atrioventricular congênito isolado

“…Na população adulta, estudos recentes têm demonstrado que a estimulação crônica do VD pode causar alterações na sequência de ativação elétrica ventricular e provocar dissincronia eletromecânica [35][36][37] . Esse fenômeno tem sido correlacionado à deterioração da função ventricular esquerda e ao desenvolvimento de insuficiência cardíaca grave.…”

“…O retardo da ativação, principalmente da parede livre do VE, em relação à do septo interventricular, tem sido referida como importante causa de diminuição da eficiência da contração, causando aumento do volume, modificação da geometria e disfunção do ventrículo esquerdo. Este fenômeno tem sido reportado, maiormente, na população adulta com distúrbios adquiridos da condução elétrica cardíaca 34,37 . A despeito do pequeno número de estudos encontrados na literatura, a dissincronia e o remodelamento ventricular também foram reportados em crianças com bloqueio AV congênito 27,29,33 .…”