Cardiac arrhythmias (irregular heartbeat) including atrial fibrillation and ventricular tachycardia are major causes of morbidity and mortality. Devices such as defibrillators and procedures like catheter-guided ablation are the current modes of therapy. However, these procedures are long and expensive with variable success rates, e.g. radiofrequency ablation- up to 50% of patients requiring additional procedures. New imaging techniques such as MRI and new computational tools have the potential to substantially impact on patient selection, procedure guidance and success rates. New devices, e.g. robotic-guided ablation, new defibrillator and pacemakers will substantially impact in this area.
Atrial fibrillation is the most common cardiac arrhythmia in humans, with over 1.5 million sufferers in the UK, 50,000 new cases and 500,000 hospital admissions per year. Treatment options range from conservative, pharmacological therapy to expensive, interventional modification of atrial structure and electromechanical function by ablation. While highly effective in appropriately selected patients, catheter intervention is inherently risky and may need to be repeated in up to 50% of patients. There is an overwhelming need therefore both to optimise the tools for selection of the most appropriate patients to whom ablation should be offered and development of those tools to maximise their efficacy in achieving transmural, contiguous ablation lesions while minimising injury to collateral structures.
Ventricular tachycardia (VT) is responsible for 75-80% of the 70,000 annual sudden cardiac deaths in England and Wales. Current prediction, prevention and management strategies are imperfect and include risk stratification based on crude markers of ventricular function, implantation of internal cardioverter-defibrillators and catheter ablation in highly selected patients with previously documented ventricular arrhythmia. The pathophysiology of VT is complex and in the largest patient group (coronary artery disease) is most commonly associated with abnormal myocardial substrate, with ischaemic or structural heart disease causing scarring of the myocardium. Ablation targeting zones of scar which are the substrate for pre-existing or future VT circuits has shown promise as both a primary and secondary prevention strategy to manage arrhythmic risk and in selected patients, to obviate the need for implantation of an implantable cardioverter defibrillator (ICD), thereby avoiding the associated risks of device infection and malfunction necessitating removal.
Cardiac magnetic resonance imaging, in conjunction with cardiac electrophysiology, provides corroboration of non-invasive structural assessment of arrhythmic risk, invasive treatment of structural targets identified non-invasively and ultimately, assessment of the tissue effect of electrophysiological intervention. In two highly technical fields, this can only be achieved by close working between Industry R&D, academics in diverse fields including bioengineering, robotics, software development, cardiac modelling, and clinical specialists in both MRI and cardiac electrophysiology.
What success may look like:
- Identification of patients at risk of cardiac arrhythmia and therefore preventive measures to avoid or retard progression to clinically manifest disease
- Improved stratification of patient populations with clinically manifest disease to identify those most likely to respond to specific treatments
- Tailoring of treatment in an individual patient to address his/her specific arrhythmic pathology
The main aims of this theme therefore are:
- To develop a patient-specific arrhythmia risk-profiling tool by combining information derived from advanced cardiac imaging and both invasive and non-invasive electrophysiological assessment
- To develop patient-specific models of cardiac electromechanical function and to use those models to predict response to arrhythmia intervention
- To develop the capability of real time catheter ablation and imaging of ablation effect within the MRI environment
- To develop robotic ultrasound and catheter systems that can be combined for therapy delivery and guided using quantitative imaging