- A majority of patients with structural heart disease and scar-related ventricular tachycardia (VT) have fast, hemodynamically unstable VT.1 In fact, up to one-fifth of the patients have only unstable VT, which precludes detailed activation and entrainment mapping.2 In addition, even in those with well-tolerated VT, procedural success can be complicated by acute heart failure as a consequence of prolonged episodes of induced VT and intravascular volume expansion; and one consequence of this acute decompensated heart failure is a significant increase in the short-term morbidity and mortality of the procedure.
- Percutaneous epicardial access (Figs. 1A and 1B) has gained wide acceptance as an interventional technique to access the pericardial space. Since its initial description1 in targeting epicardial circuits of ventricular tachycardia (VT) in patients with Chagasic cardiomyopathy, percutaneous epicardial access and ablation has come to play an important role in interventional electrophysiology. This technique has been recognized as a vital addition to catheter ablation of certain cardiac arrhythmias and for the delivery of newer investigational devices such as epicardial suture ligation of the left atrial appendage.
- Electrophysiology laboratories commonly use closely spaced bipolar recordings for mapping. However, unipolar recordings have some useful features that can provide additional complimentary information, provided the limitations of these recordings and the particular recording techniques are recognized.