Evaluation of hemodynamic changes in patients with mitral valve replacement using dobutamine stress echocardiography.

Objective: The aim of this study was to investigate the response of heart to stress according to the size of the prosthetic valve in patients who had undergone mitral valve replacement by using dobutamine stress echocardiography (DSE) and to evaluate the relationship between the size of the prosthetic valve and cardiac recovery-remodeling process.

Methods: Thirty-nine patients, who had undergone mitral valve replacement were compared in terms of left ventricular diameters, systolic functions and cardiac mass indexes in order to investigate the effect of the mechanical valve size on postoperative cardiac remodeling in this longitudinal study. They were divided into three groups according to their valve size: Group 1 (valve size<29 mm, n=11), Group 2 (valve size=29 mm, n=11) and Group 3 (valve size>29 mm, n=17). Statistical analysis was performed using Chi-square and one-way ANOVA tests to determine the statistical differences between the groups. The repeated measurements of two-way ANOVA test was used to analyze effects during long-term follow-up.

Results: Only Group 1 patients achieved a significant decrease in terms of left ventricular mass index and end-diastolic diameter (138.3+/-29.7 g/m2 vs 86.6+/-15.6 g/m2 and 5.1+/-0.5 cm vs. 4.4+/-0.4 cm, p<0.05). Group 3 patients' left ventricular ejection fraction become worse after the operation (64.0+/-5.6% vs. 55.9+/-6.5%, p<0.05). Maximum and mean pressure gradients across the mitral prosthesis as well as pulmonary artery pressure were significantly increased in all groups during DSE. Maximum gradients increased from 14.2+/-4.6 to 20.7+/-7.5 mmHg in Group 1 (p<0.05), 11.6+/-4.7 to 16.2+/-6.8 mmHg in Group 2 (p<0.05), and 10.6+/-3.1 to 20.8+/-12.7 mmHg in Group 3 (p<0.05). Isovolumic relaxation time decreased in all groups following the dobutamine infusion, as expected, but this decline was not significant in Group 3.

Conclusion: A worsening in left ventricular systolic function was observed in large- sized valve prosthesis group. Only the patients who had undergone MVR with small-sized valve prosthesis achieved a decrease in cardiac mass index and preservation of the systolic function. The echocardiographically determined differences and mass index that appeared after the operation may point out that, the effect of the operation on cardiac remodeling can be related with the ventricular size.