Variations in the Pulmonary Venous Ostia of the Left Atrium: A Cross-sectional Study

Introduction: The left atrium typically receives the terminations of two pulmonary veins from each lung. The pulmonary veins are an important source of ectopic beats, initiating frequent paroxysms of atrial fibrillation. There is a paucity of data on the variations in the number of pulmonary veins in population of Karnataka. Aim: To assess the variations in the number of right and left pulmonary veins draining into left atrium and to classify the variations in pulmonary veins according to the pulmonary vein and ostial number-based classification system. Materials and Methods: A cross-sectional study was undertaken on 40 normal adult cadaveric human hearts aged 18-70 years belonging to the Department of Anatomy of Sri Atal Bihari Vajpayee Medical College and Research Institute in Bengaluru, Karnataka, India. The study was conducted from July 2024 to December 2024. The left atrium was observed from the outer aspect after removing the heart from the cadaver according to Cunningham’s dissection manual. Pulmonary ostia were observed from the inner aspect after incising the posterior wall of the left atrium. The variations noted were classified according to the pulmonary vein and ostial numberbased classification system. The observations made were presented using descriptive statistics such as frequencies and percentages. Statistical analysis was made using the software Statistical Package for Social Sciences (SPSS) version 24.0. Results: Out of 40 specimens, the normal pattern of two right pulmonary veins draining through two separate ostia into left atrium was reported in 39 (97.5%) specimens and the normal pattern of two left pulmonary veins draining through two separate ostia into left atrium was seen in 38 (95%) of specimens. Two specimens had single left pulmonary vein with single ostium in the left atrium and they belonged to type 1A. An accessory middle pulmonary vein along with typical two right pulmonary veins draining through 3 independent ostia into the left atrium was observed in a heart specimen which belonged to type 3A. Conclusion: The present study reported that the most common pulmonary vein drainage pattern was two pulmonary veins draining through two separate ostia into left atrium on each side.