Variations in the pulmonary venous ostium in the left atrium and its clinical importance

Introduction: During early embryonic development, absorption of pulmonary venous network by the left primitive atrial chamber results in opening of four pulmonary veins which drain independently into its chamber. The extent of absorption and hence, the number of pulmonary veins which open into the left atrium, may vary. As only few studies have been done, which have shown such variations, the present study was done to evaluate the possible variations in the pulmonary veins which opened into the left atrium. Materials and Methods: Fifty formalin fixed adult cadaveric hearts were studied for variations in the opening of the pulmonary veins into left atrium. Results: Our results showed that 68% of the hearts which were studied, showed usual pattern of 2 pulmonary veins on either side, while remaining 32 % hearts showed variations in the number of pulmonary veins which opened. 12% of the hearts showed 2 left and 3 right pulmonary veins, 14% of hearts showed 2 left and 1 right veins, 4% hearts showed 1 left and 2 right veins and 2% hearts showed 1 left and 4 right pulmonary veins opening into the left atrium. Conclusion: Knowledge on such variations gains significance in isolation for radiofrequency ablation as a treatment for atrial fibrillation.