This is a pilot study into the effects on heart function when pacing the right ventricle (RV). This study aims to enrol a population with structurally normal hearts. The investigators aim to measure heart function directly when pacing.

When normal conduction within the heart fails, the treatment may be to implant a permanent pacemaker. Pacing involves passing a lead via a vein to the heart and using an electrical impulse to stimulate a beat. The usual site for pacing is the tip of the RV. This has been shown to be less efficient than the normal conduction system of the heart and in some cases leads to markedly reduced function. What the investigators do not know is why this is the case.

Much effort has been directed at looking at features within the left ventricle (LV) for markers of disease progression but little has been investigated regarding the RV.

There may be some benefit to pacing the heart preferentially from different parts of the RV and the investigators aim to measure if any differences are detectable from stimulating the heart at various sites within the RV.

Inclusion Criteria;

• Patients undergoing elective Electrophysiological Studies +/Ablation
• Age 18-80
• Normal Heart on Pre-procedural Echocardiogram

Exclusion criteria;

• Atrial Fibrillation
• Evidence of anterograde conducting accessory pathway
• Permanent Pacemaker insitu
• Pregnant
• Breast Feeding

Outcome Measures; Change in load-independent indices of LV and RV contractility before and after pacing intervention. LV and RV function measured by transthoracic echocardiography and tissue Doppler imaging.

Inclusion Criteria:

• Patients undergoing elective Electrophysiological Studies +/Ablation
• Age 18-80
• Normal Heart on Pre-procedural Echocardiogram

Exclusion criteria:

• Atrial Fibrillation
• Evidence of anterograde conducting accessory pathway
• Permanent Pacemaker insitu
• Pregnant
• Breast Feeding

Patients undergoing SVT studies