1 | INTRODUCTION
Pulmonary veins (PVs) are blood vessels which distribute oxygenated blood from lungs to the left atrium (LA) of the heart. Blood inflow to the LA is generally described as a system of four PVs, arranged in pairs, each located on the right and left side of the LA. The four most commonly occurring vessels are left superior pulmonary vein (LSPV), left inferior pulmonary vein (LIPV), right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV) (classical type). However, a substantial number of variations in quantity, arrangement and morphometric dimensions of the PVs can be observed. Atrial fibrillation (AF) is the most common arrhythmia, and its incidence increases significantly with patients’ age . Both PVs and the LA play a significant role in the pathogenesis of AF. Myocardial sleeves of the distal PVs form simple extensions of the left atrial myocardium over the outer surface of PVs and they are the major source of ectopic beats . A detailed anatomical knowledge about PVs can be useful while preforming catheter ablation in the treatment of AF, may result in higher effectiveness of surgical therapies and can aid radiological examination of the pulmonary and heart area . Therefore, the aim of this study was to establish the most accurate and up-to-date anatomical knowledge of PVs ostia variations, diameters and ostial area.