Następstwa stymulacji wierzchołka prawej komory — czas na sformułowanie praktycznych wniosków? Right ventricular apical pacing sequelae — time for conclusions?
Year: 2005
Type: article
Abstract: Results of MOST and DAVID trials, which showed higher morbidity and mortality in pts paced DDD mode at ventricular apical in comparison to atrially paced patients, restored interest in the effects of (standard) right ventricular apex pacing.Review of literature shows that this pacing mode causes a lot of unfavorable effects.Abnormal activation makes earlier activated fibers (septum) contract mainly during isovolumic contraction period and this contraction minimally increases during ejection period with subseguent premature relaxation.The opposite takes place at late activated regions (basal postero-latelar left ventricular wall); initially myocardial fibers stay significantly expanded so that to redouble contraction with later delayed relaxation which adversely influences ventricular filling.Modified activation changes ventricular contraction patterns: prolongs isovolumic contraction leaving less time for ejection.Mitral regurgitation, caused by premature septal contraction, when papillary muscles are not contracted due to slow muscular conduction, contributes to unfavorable effect of right ventricular apical pacing.Asynchronic contraction of septal and lateral wall aside depresses the pump function, leads to (post pacing) remodeling of the left ventricle (asymetric hypertrophy and later dilatation with myofibres disarray).Abnormal sequence of activation increases heart catecholamine concentraction and impairs myocardial blood flow as well.Results of experimental research and clinical observations were confirmed also by findings of other trials (Danish Pacemaker Study, Pacemaker Selection in the Elderly, A Randomized Comparison of Atrial and Dual-chamber Pacing) and confirm the significance of the range of the problem (right ventricular apex remains a standard site of ventricular pacing).Another, alternative, less unfavourable ventricular pacing modes are searched.Just now in pts.with sinus node disease and DDD unit, AAI pacing or long AV delay (using AV histeresis) programming should be considered, enabling native conduction and avoidance of unnecessary ventricular pacing.In patients with heart failure or low ejection fraction demanding permanent ventricular pacing, another ventricular pacing mode (right ventricle output tract pacing, dual site right ventricle pacing, biventricular pacing or single site left ventricle pacing) should be considered.
Source: Via Medica Journals
Author: Andrzej Kutarski
Language: Polish
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2288408012