At the wall of the left atrium four pulmonary veins deliver oxygenated blood into the left atrium. Commonly, there are four pulmonary veins with separate ostia into the left atrium. Knowledge of aberrant pulmonary veins such as accessory or conjoined veins and incidental left atrial diveicula can help guide procedures to ensure isolation of the electrical potentials arising from all the pulmonary veins and avoid potential complications from attempts to enter atrial diveiculum.