ABSTRACT
Abnormalities of cardiac electrophysiology (EP) can result in brady- or tachy-arrhythmias. Bradycardia and pacemakers are discussed in a subsequent chapter. In practice, most tachycardias arise through either a focal or re-entrant mechanism. The patient history should be the starting point. Sustained episodes of palpitation should be differentiated from brief intermittent symptoms due to ectopic beats. Sudden onset and offset of episodes are typical for supraventricular tachycardia (SVT). Once an arrhythmia has been documented, further invasive investigation with EP studies can be performed. This is often combined with therapy, e.g. radiofrequency (RF) ablation for convenience. EP studies are performed in a cardiac catheter laboratory with good quality fluoroscopic imaging and further specialised equipment including a computer-based multichannel recording system and programmable stimulator, and a RF generator for ablation. In order to access the endocardial surface of the left side of the heart, the options lie between atrial trans-septal puncture or retrograde access across the aortic valve via the femoral artery.
