Electrical activity of the pulmonary vein and its interaction with the right atrium in the guinea‐pig.

Abstract

SUMMARY1. The tunica media of the proximal segments of the pulmonary vein is made up of cardiac muscle cells. The electrical activity of this cardiac portion of the pulmonary vein was studied with intracellular micro-electrodes in isolated preparations.2. All-or-none action potentials were recorded in all cardiac muscle cells in response to electrical stimulation. These action potentials did not propagate into the adjoining smooth muscle cells.3. There were differences in properties between cells at the distal end of the cardiac pulmonary vein close to the smooth muscle and those close to the heart. In quiescent preparations, cells at the distal end had resting potentials which averaged 66 mV compared with 71 mV at proximal sites. Action potentials were also smaller and shorter in duration in cells at the distal end.4. In spontaneously active preparations, pace-making potentials were observed in cells at the distal end while cells close to the heart showed a stable diastolic potential between action potentials. The spontaneous activity of the pulmonary vein was influenced by both inhibitory and excitatory nerves.5. The interaction between the pulmonary vein and atrial activities was studied in spontaneously active atrial-pulmonary vein preparations. Action potentials recorded from the pulmonary vein always followed those from the right atrium. Electrical stimulation at the pulmonary vein generated action potentials that propagated back into the right atrium.6. This study demonstrated that isolated pulmonary veins were capable of independent pace-making activity. However the activity of the pulmonary vein was dominated by the SA node in atrial-pulmonary vein preparations under normal conditions.

Distinctive Electrophysiological Properties of Pulmonary Veins in Patients With Atrial Fibrillation

“…However, action potentials at the distal end of PVs were previously reported to be shorter than those of more proximal segments and LA in guinea pigs, 9 consistent with the results of the present study.…”

Murine pulmonary myocardium: Developmental analysis of cardiac gene expression

“…Cheung demonstrated that the pm in the guinea pig is electrically active and normally is dominated by the pace making activity of the SA node (Cheung, 1980). This is consistent with earlier work which showed that the pm of dogs constitutes a functional syncytium with the atria (Spach et al, 1972;deAlmeida et al, 1975).…”

“…This is consistent with the hypothesis that the pm functions to pre-load the atrium after contraction (in the absence of a reservoir). However, evidence that pulmonary myocardial excitation propagates from the atrium toward the lung (MacLeod and Hunter, 1966;deAlmeida et al, 1975;Cheung, 1980) is easier to reconcile with the hypothesis that the muscle serves as a pulmonary venous valve. Assigning a function to the pm will have to await experimental evidence for a physiological role of the organ.…”

ACC/AHA/ESC Guidelines for the Management of Patients With Supraventricular Arrhythmias—Executive Summary

“…Tissues exhibiting abnormal automaticity that underlie SVT can reside in the atria, the AV junction, or vessels that communicate directly with the atria, such as the vena cava or pulmonary veins. 8,9 The cells with enhanced automaticity exhibit enhanced diastolic phase 4 depolarization and, therefore, an increase in firing rate compared with pacemaker cells. If the firing rate of the ectopic focus exceeds that of the sinus node, then the sinus node can be overdriven and the ectopic focus will become the predominant pacemaker of the heart.…”