Ventricular Arrhythmias in the Patient with a Structurally Normal Heart.

Ventricular arrhythmias (VAs) are among the most common cardiac rhythm disturbances encountered in clinical practice. Patients presenting with frequent ventricular ectopy or sustained ventricular tachycardia represent a challenging and worrisome clinical scenario for many practitioners because of concerning symptoms, frequent associated acute hemodynamic compromise, and the adverse prognostic implications inherent to these cases. While an underlying structural or functional cardiac abnormality, metabolic derangement, or medication toxicity is often readily apparent, many patients have no obvious underlying condition, despite a comprehensive diagnostic evaluation. Such patients are diagnosed as having an idiopathic VA, which is a label with specific implications regarding arrhythmia origin, prognosis, and potential for pharmacologic and invasive management. Further, a subset of patients with otherwise benign idiopathic ventricular ectopy can present with polymorphic ventricular tachycardia and ventricular fibrillation, adding a layer of complexity to a clinical syndrome previously felt to have a benign clinical course. Thus, this review seeks to highlight the most common types of idiopathic VAs with a focus on their prognostic implications, underlying electrophysiologic mechanisms, unique electrocardiographic signatures, and considerations for invasive electrophysiologic study and catheter ablation. We further address some of the data regarding idiopathic ventricular fibrillation with respect to the heterogeneous nature of this diagnosis.

Catheter Ablation of Ischemic Ventricular Tachycardia Originating from an Inferobasal Right Ventricular Scar Using Substrate Mapping: A Case Report.

Catheter ablation of ventricular tachycardia (VT) has emerged as a superior alternative to antiarrhythmic drug therapy in patients with ischemic cardiomyopathy, with the vast majority of ischemic VT being ablation from the endocardial surface of the left ventricle (LV). While rare, the possibility of ischemic right ventricular (RV) VT should also be entertained, especially in patients with previous myocardial infarction and in those individuals in whom LV endocardial ablation fails to abolish VT. Further, success rates remain disappointing in some of these cases, often owing to difficulties in mapping the tachycardia due to hemodynamic instability during VT. We report a case of hemodynamically unstable ischemic VT successfully ablated from the endocardial surface of the LV and RV using a substrate mapping approach in a patient with a large inferior myocardial infarction, involving RV infarction.