AbstractBackgroundThe pulmonary veins are covered by a myocardial layer, which is often an electrical substrate for atrial fibrillation. The aim of this study was to study the morphologic characteristics of the myocardial sleeves of pulmonary veins by examining a large group of freshly autopsied human material.Methods and ResultsThe study macroscopically examined a total of 498 pulmonary veins draining the left atrium (120 unpreserved human hearts). In 75.0% of specimens, a classical pulmonary venous pattern was observed. The remainder of specimens either had an additional middle right pulmonary vein (20.0% of cases) or a common left pulmonary vein (5.0% of cases). Among all the veins seen in the classical pulmonary venous drainage type, the left superior pulmonary vein had the longest myocardial sleeves (9.4 ± 4.6 mm; coverage = 60.1 ± 19.4%), followed by the left inferior pulmonary vein (6.6 ± 3.5 mm; coverage = 47.6 ± 18.3%), the right superior pulmonary vein (6.0 ± 2.7 mm; coverage = 50.5 ± 13.9%) and then the right inferior pulmonary vein (5.0 ± 2.8 mm; coverage = 45.6 ± 16.2%; analysis of variance p < .001). In hearts with an additional right pulmonary vein, this vessel had the shortest myocardial sleeves (2.7 ± 1.1 mm; coverage = 36.0 ± 11.6%). In hearts with a common left pulmonary vein, the myocardial sleeves had the longest course for the common vein (13.7 ± 4.4 mm; coverage = 79.7 ± 4.9%).ConclusionsMyocardial sleeves of the pulmonary veins were seen in each examined specimen, however, their length varied significantly. In hearts with a classical venous drainage pattern, the left superior pulmonary vein had the longest sleeves. When present, an additional middle right pulmonary vein had the shortest myocardial sleeves, while the left common pulmonary vein had the longest sleeves.