Cardiac electrical mapping is an important tool that allows doctors to study the electrical activity of the heart in detail. Electrical mapping systems used in clinical practice are time consuming, invasive and very costly. Ultra-high frequency electrocardiography is a novel non-invasive cardiac mapping system. Ultra-high frequency electrocardiography (UHF-ECG) can be performed in 10-15 minutes without any risk or discomfort to patients.

The aim of this study is to refine this mapping system, verify it against invasive mapping and develop software to bring this novel system into routine clinical use including predicting which patients will respond to cardiac resynchronisation therapy.

This is a single centre laboratory study aiming to utilise ultra-high frequency electrocardiography to construct cardiac electrical activation maps.

All participants will attend for an UHF-ECG. This involves placing standard electrocardiography electrodes (up to 48) followed by electrocardiography recording using the UHF-ECG machine for 10-15 minutes.

Participants undergoing a clinically indicated VT ablation procedure will their UHF-ECG done before the procedure at a separate time. The ablation procedure itself will proceed as standard with no alternation whatsoever in study participants and no invasive measurements will be undertaken during the procedure. After the procedure is complete the 3D electrical maps collected to guide VT ablation will be analyzed and used for the study. The invasive maps will be compared with the non-invasive maps obtained using UHF-EGC.

Inclusion Criteria:

• Adults (age > 18 years)
• Able to give consent
• Some patients will be recruited from those listed for a clinically indicated VT ablation
• Patient subgroups as follows; 60 participants with LBBB undergoing a clinically indicated VT ablation , 20 participants with normal 12 lead ECG and normal left ventricular function assessed using standard echocardiography, 20 participants with right bundle branch block morphology on 12 lead ECG, 40 participants with non-specific conduction delay on 12 lead ECG, 60 participants with left bundle branch block morphology on 12 lead ECG and 20 participants who developed left bundle branch block morphology on 12 lead ECG after undergoing aortic valve replacement

Exclusion Criteria:

• Unable to give consent
• Children (age < 18 years)