This thesis studies techniques for maximising the effects of Cardiac
Resynchronisation Therapy (CRT) which is a modern therapy for chronic heart
failure.
The ability of echocardiographic parameters of mechanical dyssynchrony to identify
suitable candidate patients for CRT, and subsequently to optimise the interventricular
delay, is disputed. In this study, I initially perform a systematic review to clarify the
nature and extent of this problem. I then perform detailed mathematical simulations to
understand what is feasible in an ideal setting.
I then evaluate the realistic potential of several non-invasive approaches of optimising
CRT devices by formal evaluation head-to-head. A fundamental requirement for any
marker in optimisation of CRT devices, or in selection of patients for implantation, is
that the marker must be reproducible and must change when the amount of
dyssynchrony changes.
I perform detailed experiments in patients where I interrogated a panel of
echocardiographic parameters to answer the questions relating to the sensitivity of
each parameter and looked at methods to improve this. I look at the effect of
spontaneous variability, and the impact on each echocardiographic method including
3D echocardiography, tissue Doppler imaging and pulsed Doppler techniques
including velocity time integrals and pre-ejection times.
Finally, I perform an invasive study of the beat to beat physiological changes which
occur after intra cardiac timings are altered, to evaluate alternative approaches to
changes in cardiac performance that might be easier to automate.