Auckland Bioengineering Institute
Cardiac Electrophysiology
This interdisciplinary research group which involves bioengineers physiologists and cardiologists is employing function-based computer models of the heart and novel measurement techniques to visualise and study electrical activity of the heart, with particular emphasis on the mechanisms that underlie arrhythmia, fibrillation and defibrillation.
The spread of electrical activity through the heart chambers is being mapped experimentally using multichannel optical and electrical probes. Computer models that include detailed information about the structure and electrical properties of the cardiac chambers are being used to generate and study "virtual" arrhythmias. Accurate computational techniques that enable the 3D spread of cardiac electrical activation to be reconstructed from electrical potentials measured on the body surface are also being refined and validated. Clinical studies are being carried out to evaluate the utility of this technique.
A bidomain model of heart tissue that incorporates microscopic information about the organization of heart muscle cells chambers of the heart is used to predict the spread of electrical activation across a segment of heart wall from a midwall stimulus. Isochronal activation surfaces are presented in the top image while tracellular potentials are presented in the lower image 10ms after activation.
Optical probes have been developed that enable cell membrane potential to be recorded at up to seven sites across the heart wall. The heart is stained with a membrane bound dye for which fluorescent emission is affected by changes in cell membrane potential. A fibre optic bundle is used deliver excitation light from a laser to sites in the heart wall and to collect the fluorescence emission adjacent to these sites. Typical optical potentials are shown in panel at right.
Clinical characterisation of cardiac electrical activity in patients. Spatial organization of maximum restitution slope (left) and range of diastolic intervals for which restitution slope is greater than unity (right) in two patients, illustrating the regional heterogeneity within patients and between patients. (AVD: aortic valve disease; CAD: coronary artery disease). Collaborative study involving Dr Peter Taggart (University College Hospital London), Dr Martyn Nash (Auckland), Dr Richard Clayton (Sheffi eld), and Prof David Paterson (Oxford).
The Cardiac Electrophysiology gratefully acknowledges the support of its funding partners:
- Health Research Council of New Zealand
- The Royal Society of New Zealand
- The Wellcome Trust
- The University of Auckland Research Committee
