This study is designed to explore whether a marker exists within the right ventricle (RV) that may suggest future pacing induced dysfunction of the heart. Pacing the heart is a necessary procedure when normal conduction has failed. It has been shown in some patients to result in deleterious effects on the pumping function of the left ventricle acutely and chronically. Little has been looked into within right ventricular function and how this interacts with the left side. The fact that this dysfunction is not seen in all patients who receive pacemakers is important and we aim to use these pure haemodynamic measures to investigate this issue and try to identify those patients who may go on to have pacing induced dysfunction. This is an important scientific question to answer as we know that these patients can be spared the ventricular dysfunction by the intervention of biventricular pacing at the time of initial implantation. What we do not know is how to choose this group at the outset.