Applications of body surface mapping in cardiac resynchronisation therapy and ventricular tachycardia

INTERVENTION: 1. CRT study This is a pilot study during which 50 consecutive patients undergoing CRT implantation will be identified and worked up appropriately (there is no control group in this study and all participants will be given the same intervenions). All participants will undergo baseline assessment to include echocardiography, 6 minute walk testing, cardiopulmonary stress testing, quality of life assessment (questionnaire) and N‐terminal Pro‐BNP measurement. Body Surface Mapping (BSM) will be performed at baseline and the day following device implantation during different pacing modalities. They will then be followed up with a single visit at 6 months, at which time all of these tests will be repeated. 2. ECGI validation study: A qualitative study comparing ECGI with data acquired invasively using noncontact endocardial mapping as gold standard. 10 patients undergoing invasive ElectroPhysiological Studies (EPS) requiring access to the left ventricle will be recruited. All patients will have an ECHO at baseline and undergo simultaneous body surface mapping and invasive endocardial mapping during muti‐site pacing of the LV endocardium. BSM utilises a plastic 80‐electrode mapping harness applied to the anterior and posterior torso. Noncontact endocardial mapping uses the previously validated EnSite 3000 system. This study will enable a qualitative comparison of both imaging modalities for localisation of pacing sites as well as activation sequences. There will be no follow‐up for the patients in this sub‐study. 3. VT study: 10 patients requiring VT ablation or simply EPS for induction of ventricular arrhythmias will be studied using both invasive and noninvasive modalities. This is a purely qualitative study. CONDITION: Left ventricular dysfunction ; Circulatory System ; Left ventricular dysfunction PRIMARY OUTCOME: CRT study: ; Response to CRT (assessed clinically using echo, 6 minute walk distance, cardiopulmonary stress testing, and functionally using quality of life questionnaire and NYHA symptom class). This can be assessed in conjunction with pacing site localisation using ECGI in relation to regions of slow conduction/scar tissue. ; ; ECGI validation and VT studies: These are qualitative studies whereby ECGI data and data acquired invasively are compared directly. Therefore there is no discrete end‐point. SECONDARY OUTCOME: No secondary outcome measures INCLUSION CRITERIA: Cardiac Resynchronization Therapy (CRT) study: 1. Poor LV function with ejection fraction on echocardiogram (ECHO) <35% 2. Symptomatic with New York Heart Association (NYHA) class 2‐4 3. Dilated LV (>55 mm) 4. Any QRS duration (representing the duration of ventricular depolarisation) LV dysfunction can be of any aetiology. All patients must be able and willing to give writted informed consent. ECGI validation study: Patients must require EPS/ablation of tachyarrhythmias requiring LV access e.g. VT ablation/EPS, Brugada EPS, left sided pathways. All must be willing and able to give written informed consent. VT study: All patients must require EPS for induction of LV tachyarrhythmias or ablation of VT. Again all must give written informed consent.