The clamp is subsequently positioned on the left atrium near the left pulmonary veins for ablation.

Below, it is joined to the upper left pulmonary vein by the ligament of the left vena cava.

Occasionally the three veins on the right side remain separate, and not infrequently the two left pulmonary veins end by a common opening into the left atrium.

Left atrium: This chamber sits opposite the right atrium and is the upper part of the heart that receives oxygen-rich blood from the lungs via the right and left pulmonary veins and pumps it through the bicuspid valve or mitral valve into the left ventricle.