Atrial Pacing in the Determination of Myocardial Function in Patients with Mitral Stenosis

¹ Professor of Medicine and Director, Division of Cardiology, Hahnemann Medical College and Hospital, Philadelphia

Abnormalities of myocardial function are frequently noted in patients with rheumatic mitral stenosis (RMS). Since ventricular function curves (VFC) relating pacing induced changes in left ventricular end-diastolic pressure (LVEDP) and stroke work (SW) have been useful in distinguishing diminished function in patients with coronary artery disease and myocardiopathy, atrial pacing was carried out during cardiac catheterization in 13 patients with RMS and compared to six normal subjects. Heart rate (HR) changes were similar in the two groups and in both groups no changes occurred in afterload or cardiac output while stroke volume, SW and LVEDP decreased. In those with RMS as LVEDP decreased during pacing, left atrial pressure and transvalvular gradient increased. VFC were abnormal in 5 of 13 with RMS when compared to the normal subjects and the VFC correlated well with clinical and angiographic findings. Atrial pacing is useful in evaluating LV myocardial function in patients with RMS and aids in the separation of myocardial from obstructive factors. Since HR changes are reproducible, it can be used for preoperative and postoperative comparisons.