The Role of Atrial Systole in Valve Closure

Report of Patient with Complete Heart Block and a Mitral Prosthetic Valve

¹ Department of Medicine, Cardiology Division and the Department of Surgery, Cardiovascular Division, Long Island Jewish-Hillside Medical Center, New Hyde Park, N.Y., Queens Hospital Center Affiliation, Jamaica; School of Medicine, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, N.Y.

A patient is reported with complete heart block, normal sinus rhythm and a mitral prosthetic valve. Studies were performed to evaluate the role of artial systole on valve closure. Cinefluorographic studies were performed which demonstrated that valvular closure may occur with either atrial or ventricular contraction. The contribution of the atrium and ventricle to valve closure was dependent on the time interval separating the contraction of these chambers. A short PR interval was associated with late closure due entirely to ventricular systole. As the PR interval increased, valvular events (onset and completion of closure) occurred earlier. At PR intervals over 275 msec the valve was completely closed before the QRS. PR intervals over 400 msec were associated with double diastolic closure of the valve. The first closure was due to atrial systole, while the second closure was due to ventricular contraction. At PR intervals over 450 msec, closure was again late and due to ventricular contraction. These observations support studies in animals that atrial systole can influence mitral valve closure.