AbstractPacemaker implantation remains the sole treatment options for patients
with bradycardia. The devices have evolved over the years, however recent
studies of implantable defibrillators suggested that increased levels of
pacing at the right ventricular apex (the conventional site) may be
associated with worse outcomes in patients with impaired left ventricular
An initial observational database linkage study was performed to investigate
the prevalence of heart failure in patients referred for pacemaker insertion.
This identified a significant portion of patients (19%) had heart failure and
were potentially at risk. Further study was undertaken in patients without
heart failure to investigate the effects of right ventricular (RV) apical pacing
on endothelial function. 22 patients with sino-atrial node disease were
exposed to high degrees of RV pacing and minimal RV pacing in a crossover
study for 1 week each. This demonstrated significant impairment of
endothelial function in the arm with a high degree of RV pacing.
A subsequent study investigated the impact of biventricular pacing
compared to RV pacing again in a cross over design. Patients were implanted with a biventricular device and randomised to RV only or biventricular
pacing. Biventricular pacing was associated with significantly enhanced 6
minute hall walk distance together with improved quality of life and less
impairment of endothelial function and reduction of hs-CRP when compared
to biventricular pacing.
Finally a further retrospective data-linkage study demonstrated that
angiotensin receptor blocker or angiotensin converting enzyme inhibitor use
was associated with improved mortality and less hospitalisation for heart
failure in patients paced for complete heart block, who were likely to be
exposed to high degrees of right ventricular pacing.
In summary this thesis is a record of my study of the effects of pacemaker
insertion in patients with impaired left ventricular systolic function. My
research has demonstrated the potential detrimental effects of right
ventricular apical pacing and has identified potential therapeutic strategies
of ameliorating these effects.
|Date of Award||2013|
|Supervisor||Anna Choy (Supervisor)|