Responding to resynchronization : improving the impact of biventricular pacing in the management of chronic heart failure

Abstract

Cardiac resynchronization therapy (CRT) is a recent therapeutic intervention that is delivered by the implantation of a biventricular pacemaker system. The mechanism of action is believed to be the correction of dyssynchrony of myocardial contraction. This approach can reduce morbidity and mortality in a select group of heart failure patients. However, many questions remain unanswered concerning the selection of patients for CRT, how to assess response to CRT and the exact pathophysiological actions of CRT. This thesis investigates some of these questions. Chapter 1 provides an overview of heart failure epidemiology, pathophysiology and current management before discussing the role of CRT in detail. Chapter 2 examines the long-term clinical impact of CRT. Clinical and echocardiographic change over time is examined in a group of patients with devices implanted longer than 2 years. It is found that both the degree of reverse remodelling during the first year and the aetiology of heart failure impact long-term outcome. Chapter 3 investigates the role of pulsed-wave tissue Doppler echocardiography as a means of assessing myocardial dyssynchrony in a prospective group of patients referred for CRT. It is shown that the degree of dyssynchrony will differ depending on the model employed to determine it. Chapter 4 explores the effect of CRT on heart failure biomarkers. It is shown that adrenomedullin, intermedin and logiohigh-sensitivity C-reactive protein are reduced after CRT. N-terminal Pro B-type natriuretic peptide appears limited as a marker of CRT response. Chapter 5 investigates the haemodynamic value of temporary biventricular pacing after coronary artery bypass grafting and concludes that it cannot be recommended routinely even in those with poor ventricular function prior to surgery. Chapter 6 contains concluding reflections on the future for CRT.

Date of Award	2009
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mark Harbinson (Supervisor) & Chew Eng-Wooi (Supervisor)