Recording of left atrial potentials from pulmonary artery in man.

The purpose of the present study was to validate the recording of left atrial activity from the pulmonary artery in man. Fifteen patients with atrial septal defect or patent foramen ovale were studied. Atrial activity was recorded simultaneously from the pulmonary artery and the high left atrium either during sinus rhythm or during paced ectopic atrial rhythm. The results have shown a close similarity between the atrial signals recorded from the proximal (that is right-sided) high left atrium and the right pulnonary artery (overlying the vertebral column) both during sinus rhythm and paced ectopic atrial rhythm. Activity from the pulmonary arterial trunk corresponded best to signals from the lateral high left atrium. The latest activity, originating probably from the lateral left atrium, was recorded from the left pulmonary artery. However, in many cases the amplitude of the signals from the left pulmonary artery was too small to allow precise definition of the onset of atrial activity. We conclude that recording atrial activity from the pulmonary artery is a valid approach for studying high left atrial activation if there is no direct access to the left atrium. When this technique is used in association with the recording of left atrial signals from the coronary sinus, left atrial activity can be analysed in detail.