Preliminary observations on haemodynamics during physiological stress conditions following 'double-orifice' mitral...

The 'double-orifice' (DO) technique has been proposed to simplify mitral valve repair (MVRep) in particular settings of mitral insufficiency. However, the haemodynamic effects of such a redesigned valve are poorly documented, particularly during stress conditions. Thus, we sought to evaluate the haemodynamic changes during exercise conditions after the DO procedure.

Twenty-seven selected patients were enrolled for this study. Mean age was 60 +/- 14 years (range 31--80 years). All patients had had severe mitral regurgitation and normal LV function preoperatively, and had undergone DO as isolated procedure for MVRep. Annular remodelling was associated in 24 cases (Carpentier classic ring in 13 patients and autologous pericardium in 11 patients, respectively). Postoperatively, haemodynamic data were recorded at baseline and during supine exercise test at submaximal workloads by means of transthoracic echocardiography. A logistic regression analysis was applied to evaluate the association between the observed haemodynamic changes and surgical technique.

Mean follow-up was 47 +/- 20 months. Significant residual mitral insufficiency (grade three over four) was found in five patients at baseline assessment, and in six patients at peak exercise. Transmitral pressure gradient showed a significant (P < 0.001) increase in both peak and mean values at peak exercise (from 7 +/- 4 to 17 +/- 10 and from 3 +/- 2 to 8 +/- 6 mmHg, respectively). Pulmonary hypertension was observed in six patients (moderate in all cases) at rest and in 13 patients (moderate in seven cases and severe in five cases) at peak exercise. We did not find any correlation between the haemodynamic data and surgical factors.

This study indicates that though effective mitral valve competence is achieved in the majority of operated patients, DO repair may induce impaired diastolic mitral dynamism in some cases, particularly during exercise conditions. Further investigations are required to thoroughly elucidate the overall mechanics of a DO valve, especially at strenuous cardiocirculatory states.