Minimally Invasive Mitral Valve Replacement

Abstract

The AV valve of the left ventricle, the mitral valve, is bicuspid, with an anterior leaflet and a posterior leaflt. The mitral valve leaflets may be described using a segmental classification that has been useful in describing morphology observed at operation, 2D transesophageal echocardiography and 3D-echocardiography.

Mixed mitral stenosis and regurgitation is primarily rheumatic in origin but there are numerous other causes and morphologic patterns.

Mitral valve prolapse occurrs as an isolated abnormality which is a relatively common and complex entity occurring in 1-2.5% of the population. Familial mitral valve prolapse is inherited as an autosomal trait. Primary mitral valve prolapse occurs with increased frequency in patients with Marfan syndrome and certain other connective tissue disorders.

Anular calcifiation is probably a degenerative disease, more common in elderly patients and apparently more common in women. It is also seen in patients with LV hypertrophy, particularly those with hypertrophic obstructive cardiomyopathy.

Papillary muscle dysfunction or rupture resulting from myocardial infarction or ischemic firosis can produce severe mitral regurgitation.

Endocarditis is a relatively uncommon cause of pure mitral regurgitation compared with its etiologic frequency in aortic regurgitation.

In most patients, mitral stenosis can be diagnosed clinically based on history, physical examination, chest radiograph, ECG, auscultatory fidings, and the characteristic diastolic rumble murmur and characteristics of heart sounds.

Minimally invasive mitral valve surgery (MIMVS) does not refer to a single approach but rather to a collection of new techniques and operation-specific technologies. These include enhanced visualization and instrumentation systems as well as modified perfusion methods, all directed toward minimizing surgical trauma by reducing the incision size. video-assisted mitral valve repair performed through a mini thoracotomy, using video-direction, a transthoracic aortic clamp, and retrograde cardioplegia.

The next major development was the introduction of a voice-controlled robotic camera arm which allowed precise tremor-free camera movements with less lens cleaning. This technology translated into reduced cardiopulmonary bypass (CPB) and cross-clamp times and enabled even smaller incisions with better valve and subvalvar visualization.

Minimally invasive valve surgery evolved through graded levels of difficulty with less exposure and to a progressive reliance on video assistance.

It was evident that the operative time (cardiopulmonary bypass and cross clamp time) for MIMVS is more than that of conventional surgery. And according to mortality, no study has shown a significant difference between minimally invasive and conventional approaches. One of the major benefits of MIMVS has been claimed to be the less bleeding related complications and less usage of blood products as compared to the conventional approach.

Recent studies have shown a decreased incidence of postoperative AF in MIMVR than the conventional sternotomy.

The incidences of septic complications and wound infections are less in thoracotomy than with sternotomy.

Postoperative pain levels reported less in MIMVR compared to sternotomy, also the time to return to normal activities noted be significant advantage for a minimally invasive approach.

The limitations for MIMVR is the learning curve is low at the beginning so, the complications at this point is high and the contraindications included poor exposure, previous surgery on right lung, lung resection or pleurodesis as well as morbidly obese patients.