Around half of patients who undergo catheter ablation for ventricular tachycardia—a dangerously fast heart rhythm caused by scar tissue—still need a defibrillator to shock their heart back into a normal rhythm, because the procedure fails to destroy the right areas of scarred muscle. This failure rate matters because VT is the leading cause of sudden cardiac death, and the defibrillator shocks that patients endure are painful, reduce quality of life, and shorten long-term survival. The core problem is that current ablation relies on indirect mapping to locate the scar, making precise targeting difficult. Professor Reza Razavi’s team at King’s College London has built a prototype system that performs ablation inside an MRI scanner, allowing direct visualisation of the scar tissue during the procedure. They have already shown it works for simple arrhythmias. This project extends that approach to VT, using real-time MRI images to guide the catheter more accurately, assess the damage immediately, and confirm that the right tissue has been destroyed. If successful, the technology could raise ablation success rates well above 50%, reduce the need for defibrillator implants, and spare thousands of patients from repeated shocks.
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Ventricular tachycardia (VT) is a form of cardiovascular disease where patients suffer from a dangerously fast heart rhythm. This results in a reduced pumping capacity of the main heart chambers, the ventricles, and is the leading cause of sudden cardiac death. The occurrence of VT is related to scar tissue formation in the heart muscle. VT is treatable using minimally invasive surgery with ‘ablation’ technology. Treatment involves destroying the abnormal scarred regions of heart muscle, this is accomplished using a catheter to deliver energy at the treatment location. The current success rates is around 50%: as a result patients still frequently require a defibrillator (ICD), an expensive implanted device that shocks the patient back into a normal rhythm. These shocks are unpleasant and impact both patient quality of life and long term survival. This study aims to use magnetic resonance imaging technology (MRI) to improve VT ablation accuracy by allowing direct visualisation of the scar that causes the VT. MRI is an imaging technology which uses non-ionising radiation to image inside the body, requiring patients to lie within a MRI scanner for the procedure. With improved ablation outcomes and higher success rates, fewer patients would receive frequent ICD shocks, and in the future it may even be possible to avoid implantation of an ICD altogether. Professor Reza Razavi’s team at KCL have developed a prototype system for treating irregular heart rhythms (arrhythmias) inside an MRI scanner and have shown in a first-in-man study that it is possible to treat simple arrhythmias using the MRI images. Application of this technology to treat VT will enable a more detailed analysis of the cause of the VT, improved targeting of the treatment and more rigorous assessment of treatment results, greatly improving patient outcomes.
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