Abstract
Many patients following cardiac surgery have supraventricular arrhythmias. Because the tricuspid valve is subjected to surgical manipulation and the canine mitral valve has been shown to be a site of ectopic impulse formation we studied isolated preparations of canine tricuspid valve (TV) and contiguous right atrial (RA) muscle by microelectrode techniques to determine if this tissue has the potential to generate arrhythmias. Unlike the action potentials (AP) recorded from ordinary atrial muscle, AP's recorded from TV-RA demonstrated low maximum diastolic potential, slow upstroke velocity, a prominent plateau phase, and a diastolic afterpotential. All preparations showed spontaneous phase 4 depolarization initially or during superfusion with catecholamines. Impulses originating in the TV conducted to RA. Acetylcholine abolished automaticity and decreased AP amplitude in spontaneously depolarizing TV cells but had minimal effect on ordinary RA cells. This data indicates that ectopic impulses can arise from cells in either TV or contiguous RA. These cells respond to autonomic agents in a similar fashion as other supraventricular pacemaker cells and perhaps may be the site of origin of some of the supraventricular arrhythmias observed postoperatively in the clinical situation.
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Gelband, H., Wit, A., Fenoglio, J. et al. TRICUSPID VALVE TISSUE AS A SITE OF ECTOPIC IMPULSE FORMATION. Pediatr Res 8, 350 (1974). https://doi.org/10.1203/00006450-197404000-00058
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DOI: https://doi.org/10.1203/00006450-197404000-00058
