[Localization of ventricular premature contractions by 12-lead ECG]

The advances in imaging and 3D mapping systems in the last decade allowed a better correlation of ventricular premature contractions (PVCs) with anatomical structures. With regard to PVCs, interpretation of the 12-lead ECG is still crucial for the management of patients and the planning of therapies. Although there is an armamentarium of indices and algorithms to exactly pinpoint the origin of a PVC in advance, a thorough understanding of cardiac anatomy and impulse propagation, together with an awareness of the surface ECGs limitations, provides a sufficiently close approximation. PVCs from the diaphragmatic part of the ventricular cavae exhibit a superiorly directed axis, whereas PVCs from superior parts of the heart show an inferior axis. A right bundle branch block morphology or positive concordance of the precordial leads yields a high probability of left ventricular origin of a PVC. A left bundle branch block morphology is indicative of a right ventricular or septal origin of a PVC. Using the transition zone, one can estimate the origin of a PVC with regard to anterior or posterior regions of the heart: A late precordial transition is indicative of a right ventricular origin, an early precordial transition suggests a left ventricular focus. An absent transition in the sense of negative concordance is indicative for an apical origin. The intertwined course of the ventricular outflow tracts makes PVC localization more difficult. Here, shape and height of the R‑wave in V₁-V₃ help to narrow the origin down. PVCs from structures like the papillary muscles, the moderator band or infundibular bands are challenging to interpret and evidence of the limitations of the surface ECG. Based on the information gained by the aforementioned approach, a prediction of prognosis and possible treatment success is possible.