STUDY OF MITRAL VALVE RESERVE CAPACITY IN PATIENTS WITH MITRAL STENOSIS (WHETHER DE NOVO OR RESTENOSIS) BY STRESS ECHOCARDIOGRAPHY

Abstract

The severity of mitral stenosis is considered to be determined by' relatior1 between valve area, transvalvular pressure gradient, and the flow across the valve. However, discrepancies between symptoms and hemodynamics at rest are frequently encountered in patients with mitral stenosis. As well, about 60 per cent of patients with mitral restenosis, defined as recurrence of symptom or mitral valve area ::; 1.5 cm2 or 50 per cent loss of initial gain, after previous percutaneous balloon mitral valvuloplasty . are found to have symptomatic improvement at rest by more than one NYHA functional class during the follow-up period. •

Consequently, resting hemodynamic data may underestimate the severity of mitral stenosis and resting echocardiographic studies may be inconclusive regarding the severity of the obstruction. Therefore, exercise echocardiography is of great value in moderate• mitral stenosis when symptoms are not matching the data obtained from Doppler pressure measurements at rest or vice versa i.e. either asymptomatic patients with severe stenosis or symptomatic patients with moderate stenosis.

During exercise, patients with symptomatic mitral stenosis develop an increase in transmitral gradient and pulmonary artery pressure from resting values. Patients with milder denree of mitral stenosis may develop significant increase in maximal diastolic" mitral valve area during exercise; a normal reaction known as mitral valve reserve capacity, compared with those with more severe degree of valvular narrowing. This increase in mitral area leads to increase the stroke volume during exercise.