ROLE OF STRESS ECHOCARDIOGRAPHY IN THE FUNCTIONAL ASSESSEMENT OF PROSTHETIC MITRAL VALVE

Objective: To assess the resting echo profile of patients with prosthetic mitral valve and monitor the function of the prosthetic valves by doing stress echocardiography by treadmill exercise and dobutamine infusion. Methods: An open-labeled prospective randomized comparative study was conducted in  30 patients at Madras Medical  College and Hospital, Chennai- 600 003, Tamil Nadu. Patients, who have been done mitral valve replacement, were selected randomly to undergo the stress echocardiography. 14 male and 16 female patients were included and evaluated on the basis of Echocardiographic examination, Exercise studies, Dobutamine stress echocardiography & Estimation of LV outflow. Results: Upon comparison, the patient's heart rate were increased from rest to exercise by a mean of 24 ±12.5 beats per minute. The paired t-test showed a significant correlation with an increase in the dobutamine group (P <0.001). With respect to peak gradients, it was increased between the two stress protocols was statistically significant (P <0.001). The mean gradient obtained at rest and with exercise and dobutamine stress also showed a similar pattern of increase as seen in the peak gradient. Moreover,  the net difference in the Pulmonary artery pressure achieved with both stress protocols was 5.563±4.6mmHg more in the exercise protocol which was statistically significant  (P <0.001). Conclusion: The study reveals Dobutamine produces a greater augmentation in the effective mitral orifice area when compared to exercise. Similarly, the exercise protocol produces a much higher increase in the pressure gradients when compared with dobutamine.