The Journal of Thoracic and Cardiovascular Surgery, Vol 71, 520-525, Copyright © 1976 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Hemodynamic effects of pacing-induced heart rate augmentation. A study in patients early after mitral and aortic valve operations
DA Mary, BC Pakrashi and MI Ionescu
Heart rate augmentation induced by atrial and ventricular pacing was
carried out in 23 patients early after intracardiac valve operations. The
series comprised two groups of patients: 11 with aortic and 12 with mitral
valve surgery. A different pattern of hemodynamic responses emerged during
heart rate augmentation in each group. Atrial pacing produced, in the
aortic group, a significant increase in cardiac output and mean aortic
pressure and a reduction in left atrial pressure. The changes in the mitral
group were not significant. During ventricular pacing the left atrial
pressure rose in both groups. Although there was a decrease in the mean
cardiac output in the aortic group and an increase in the mitral group,
these changes did not reach statistical significance. A similar distinction
between the aortic and mitral groups was observed when comparing the
results of atrial and ventricular pacing at the same heart rate. The
hemodynamic benefit appeared to be confined to the aortic group. The
different pattern of response in each group of patients was probably due to
clinical, hemodynamic, and therapeutic factors related to the condition and
management of patients with each type of valve surgery.
