Anatomy of the Pericardial Space and Mediastinum: Relevance to Epicardial Mapping and Ablation.

The pericardial space is a fairly new portal for interventional cardiac electrophysiologists to access the heart and requires an understanding of its anatomic peculiarities to maneuver safely around the epicardial surfaces of the heart and great veins. Subxiphoid puncture should allow the diaphragm and fibrous pericardium to be crossed without entering the right ventricle, which is the most anteriorly situated cardiac chamber. The phrenic nerves descend on the fibrous pericardium bilaterally. The right nerve is related to the superior caval vein and the superior right pulmonary vein, whereas the left nerve takes variable courses over the left atrial appendage and the left ventricle. Related to the fibrous pericardium overlying the posterior wall of the left atrium is the esophagus.