The close anatomical relationship between the coronary arteries and the myocardial infundibulum of the right ventricle: a potential cause of coronary injury after catheter ablation of RVOT tachycardia

Abstract

Thermal damage to coronary arteries during catheter ablation has been previously reported. The anatomical relationship between the right ventricular outflow tract (RVOT) and the coronary arteries has not been thoroughly studied. Our purpose was to define the relationship between the outer layer of myocardium and endocardium of the RVOT and the coronary arteries. We examined 35 human hearts (22m; 59±8years) by dissection techniques (8 hearts) and histologic sections (27 hearts). We studied the minimum distance from the right coronary artery (RCA), left main coronary artery (LMCA), left anterior descending (LAD) and conal coronary artery (CCA) in the area bounded superiorly by the plane of the pulmonary valve, inferiorly by the superior margin of the RV inflow, and laterally by the anterior interventricular groove. Paraseptal regions of the RVOT are in close proximity to the LMCA, RCA, LAD and CCA; in most cases within the circumjacent of potential ablation sites. The minimum distance from the LMCA to the myocardial outer layer of the RVOT was 4.8±1.2 mm. Distances from the LAD and RCA to the myocardial outer layer of the RVOT were 2.1±0.9 mm, and 2.3±0.8 mm, and to the endocardium were 6.4±1.9 mm, and 6.3±2.5 mm (avge±SD). The CCA took off directly from the right aortic sinus in 10 of 35 hearts (29%) while it arised from the proximal RCA in the remaining hearts (71%). The minimum distance between the CCA and the outer layer of myocardium and endocardium of the RVOT were 1.3±0.3 mm,and 5.5±1.2 mm. In conclusion, the distance between the major coronary arteries and the epicardial or endocardial ablation sites of the RVOT is usually less than 5 mm. This close relationship must be kept in mind during ablation of RVOT tachycardias in order to avoid injury of the coronary arteries.