The Effect of Heart Rate on Tricuspid Annular Velocities in Cardiac Surgical Patients With Atrial Fibrillation

Objectives: Tricuspid annular isovolumic acceleration is a load-independent measure of contractility, but its relationship to heart rate is unknown in humans. The authors investigated the effect of heart rate on measurements of isovolumic acceleration and systolic wave velocities in postoperative cardiac surgical patients with atrial fibrillation.Design: This was a prospective observational study.Setting: Single-university hospital setting.Participants: Postoperative cardiac surgical patients with atrial fibrillation.Interventions: None.Measurements and Main Results: Lateral tricuspid isovolumic acceleration and peak systolic wave velocity were measured using color-tissue Doppler. The corresponding heart rate was calculated from the preceding R-R interval. Regression analysis was used to assess the relationship between heart rate and tricuspid annular velocity. A heart rate threshold value was determined at which the tissue Doppler variables were significantly altered by heart rate. Seven hundred fifteen beats in 15 patients were analyzed. There was a positive linear correlation between isovolumic acceleration and heart rate and a negative polynomial correlation between the systolic wave and heart rate. A significant reduction in systolic wave velocity occurred at heart rates greater than 110 beats/min.Conclusions: In this patient population, isovolumic acceleration significantly increased with increasing heart rate. Tachycardia-induced preload alterations and impaired force-frequency responses may have been responsible for the decrease in systolic wave velocities.