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Mechanisms by which cardiac resynchronisation therapy improves cardiac performance in heart failure

Williams, Lynne Kirsty (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

This thesis assesses the mechanisms by which biventricular and left ventricular pacing improves cardiac performance in patients with heart failure. We demonstrated for the first time that CRT results in an improvement in acute haemodynamic variables in heart failure patients with a narrow QRS duration that is comparable to the effects seen in heart failure patients with a broad QRS duration. In addition, we have shown that both biventricular (BIVP) and left ventricular pacing (LVP) significantly reduce external constraint to left ventricular filling, resulting in an increase in effective filling pressure. In heart failure patients with evidence of external constraint at rest, the acute haemodynamic benefits of both BIVP and LVP were principally due to the relief of external constraint and preload recruitment. However, in those patients with evidence of electrical dyssynchrony and a broad QRS duration, a significant haemodynamic benefit was derived from an enhancement in left ventricular contractility, presumably as a result of a reduction in left ventricular dyssynchrony. Patients with external constraint appear to derive a greater haemodynamic benefit from pacing due to the significant increase in stroke work that is associated with relief of external constraint and preload recruitment, in addition to the increase in stroke work derived from enhanced contractility due to a reduction in dyssynchrony. These findings will inform better patient selection for this therapy and also optimisation of pacing strategy in individual patients.

Type of Work:Ph.D. thesis.
Supervisor(s):Frenneaux, Michael
School/Faculty:Colleges (2008 onwards) > College of Medical & Dental Sciences
Department:Department of Clinical and Experimental Medicine
Subjects:R Medicine (General)
RC Internal medicine
Institution:University of Birmingham
ID Code:1051
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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