Minimally Invasive Mitral Valve Surgery: Partial Sternotomy Approach

Most common indications for mitral valve replacement are rheumatic mitral stenosis and infective endocarditis. Replacement is less commonly performed for degenerative disease and functional mitral regurgitation.

Mitral valve repair is indicated in those with severe myxomatous disease with the presence of gross redundancy of both anterior and posterior leaflets, especially in the younger population. In older adults, mitral regurgitation usually is a result of fibroelastic deficiency disease.

Long-standing, severe mitral stenosis results in pulmonary hypertension, right ventricular dysfunction, and a variable degree of tricuspid valve regurgitation. If severe, this can result in secondary hepatic and renal dysfunction, with a resultant increase in operative risk.

Mitral annular calcifications are frequently present in older adults, especially in cases of rheumatic mitral stenosis. Calcifications typically involve the posterior aspect of the mitral annulus and can extend to the base of the posterior leaflet and the base of the left ventricle. Severe calcification of the mitral annulus appears as a horseshoe sign on the preoperative chest radiograph or coronary angiogram ( Fig. 20.2 ).

Standard preoperative assessment of mitral valve disease is performed by transthoracic or transesophageal echocardiography. Transesophageal echocardiography allows more precise assessment of the anatomy and function of the mitral valve and represents the gold standard in preoperative assessment and planning of the operation. It is an essential tool intraoperatively for assessment of the valve repair or replacement after weaning from cardiopulmonary bypass.

Mechanical prostheses are indicated for patients younger than 65 years; biologic valves are used more commonly in older adults. This paradigm may shift as the valves evolve in quality and durability, along with the possibility of the use of catheter-based prostheses.

Selection of the surgical approach depends on the cause of the mitral valve disease, the presence of concomitant coronary or valvular disease, body habitus, and anatomic chest wall deformities.

Most patients who require isolated mitral valve surgery are candidates for a minimally invasive approach. Relative contraindications to a minimally invasive approach include morbid obesity and extensive mitral annular calcifications.