over the past decade , minimally invasive approaches to mitral valve surgery have been commonly used at many centers around the world with excellent short- and long - term outcomes .
there has been great enthusiasm about their performance because they have proven to be at least as good and safe as the standard sternotomy approach , even in elderly patients .
a variety of approaches   have been reported , aimed at reducing surgical trauma and postoperative morbidity while remaining safe and effective .
some approaches have been aided by the use of thoracoscopy , specially designed retractors and surgical clamps as well as special instruments for long - distance knot - tying .
the right thoracotomy approach has been the most appealing , for reasons of cosmesis and reduced trauma .
however minimally invasive mitral valve surgery ( mimvs ) is performed , the most important consideration is that the approach must yield results equal to or better than those of the approaches it modifies or replaces .
there has been increasing interest in simplifying the operation so that it can be widely applied to benefit patients .
this report illustrates a simplified , reproducible minimally invasive approach with optimal access to and exposure of the mitral valve ( mv ) under direct vision .
we applied this approach to all patients with moderate and severe mv insufficiency and/or stenosis of various etiologies , with no concomitant coronary artery disease or aortic valve regurgitation .
even complex repair procedures for severe bileaflet prolapse in patients with barlow s disease can be successfully performed through this approach .
mv surgery using any commercially available prostheses can be performed with the same reliability in patients in whom the mitral valve is not amenable to repair .
it is also a useful alternative for patients requiring mv procedures after a previous cardiac operation , particularly in those with patent coronary artery bypasses or previous aortic valve replacement .
this may also be applied in patients who had had surgeries via right thoracotomy approach .
assessment of mitral valve lesions the degree of mv insufficiency or stenosis is estimated by means of standard echocardiographic measurements .
assessment of mv function includes measurement of the mitral annulus , evaluation of leaflet mobility and coaptation , determination of mitral valve orifice area , mitral flow assessment using continuous wave doppler , and valve anatomy evaluation as to valve thickness and pliability and morphology of the subvalvular apparatus .
standard guideline in mimvs using the simplified approach because the mitral valve is a posterior structure , excellent exposure can be established through the right anterolateral thoracotomy .
a simplified right anterolateral thoracotomy approach includes a 10 - 12 cm incision , either direct aortic or peripheral arterial cannulation and direct bicaval canulation , with standard retractors .
under general anesthesia using a double lumen endotracheal tube , the patient is placed in left lateral position with the chest elevated to about 45 - 60 ( figure 1a ) .
the right arm is placed over the head at approximately 120 with the elbow joint in the right - angle position .
the operating table is rotated leftwards and the patient is bent at the 12 thoracic vertebra .
transcutaneous defibrillation pads ( philips multifunction electrode pads , philips , amsterdam , the netherlands ) are placed at the left lateral chest wall and right shoulder .
a 10 - 12 cm skin incision over the fifth anterolateral intercostal space is made beginning in the skin fold below the right breast ( figure 1b ) .
the right lung is deflated and the chest cavity is entered without division or resection of any bone .
standard chest retractors are used and , under direct vision , the pericardium is incised parallel and approximately 3 - 4 cm anterior to the phrenic nerve .
this provides optimal and excellent visualization and access to the ascending aorta and superior vena cava .
heparin is administered and arterial cannulation is performed either directly in the ascending aorta or in the common femoral artery ( only in patients with a small and narrow chest ) with direct bicaval cannulation with caval snares ( figure 1c ) .
adequate myocardial protection is achieved with intermittent blood cardioplegia through a cardioplegia needle in the aortic root .
the ease and handling of myocardial protection provides no difficulty and is comparable when the approach is through a standard median sternotomy . after clamping the ascending aorta with a straight clamp having a flexible handle ,
the left atrium is opened by incising the interatrial groove with a vent cardiotomy sucker placed directly towards the left pulmonary veins .
a retractor is placed to elevate the interatrial septum , exposing the mitral valve , and the valve is meticulously inspected to determine the precise nature of the lesion .
leaflet coaptation is assessed with transvalvular saline injection under pressure . using a nerve hook , leaflet coaptation and the presence of sufficient tissues along the coaptation plane
depending on the results of this evaluation , mitral valve repair or replacement is performed under direct vision , using precisely the same approach as in a conventional median sternotomy .
modified gerbode plication plastic   is applied for posterior leaflet prolapse , ruptured chordae and in ischemic mitral insufficiency ( mi ) .
prolapse can occur anywhere along the posterior leaflet but is most commonly found in the region of p2 , which may lead to chordal rupture.in this technique , the flail segment is plicated towards the left ventricle in a v - shaped fashion with interrupted mattress sutures using double - ended 3 - 0 polypropylene with untreated autologous pericardial pledgets .
when competence and size are satisfactory a strip of untreated autologous pericardium is sutured continuously onto the posterior annulus without further annular narrowing . modified paneth - hetzer posterior annulus shortening technique
this is performed by running a pericardial - pledgeted 3 - 0 polypropylene suture through the fibrous body of the trigone and tying it
. then it is run along the annulus from one trigone towards the middle of the posterior annulus .
these sutures are then tied over an appropriately sized ziemer - hetzer valve sizer to prevent over - narrowing of the valve orifice .
then , with a continuous suture , the pericardial strip is attached to the posterior annulus from the midsegment towards the trigone .
the leaflet coaptation is tested by a forceful injection of saline through the valve , to look for residual regurgitation .
we also use this technique in anterior leaflet prolapse ; the then wider coaptation plane will eliminate prolapse .
evaluation of the adequacy of repair after mv repair , it is obligatory to assess the valve function before closure of the atrium and separation from cardiopulmonary bypass ( cpb ) .
any remaining areas contributing to significant incompetence must be attended to before closure of the atrium .
once de - airing has been completed and extracorporeal circulation is discontinued , the repair result must be further evaluated with intraoperative transesophageal echocardiography ( tee ) in order to test for inadequate mitral opening area , residual incompetence , myocardial ischemia due to coronary kinking and presence of the systolic anterior motion ( sam ) phenomenon .
immediate and prompt correction must be made if the repair is shown to be unsatisfactory .
regardless of the underlying pathology and techniques used , no patient should be discharged from the operating room with more than minimal mi .
mitral valve replacement if it is established that the mitral valve lesion is not amenable to repair , the valve is replaced , with either a mechanical or biological prosthesis , in accordance with the patient s wishes . in both procedures ,
no specially designed instruments are required , and the knots may be tied by hand or with a knot pusher .
several strategies of knot tying have been learned with experience , such as having the assistant hold up the annular sutures during knot tying . after completion of the procedure ,
the left ventricle is vented with a catheter positioned across the valve and the atriotomy is closed .
caval snares are snugged tight when tricuspid valve reconstruction ( double - orifice - valve technique )   or closure of patent foramen ovale are performed , and these procedures are done through right atriotomy . throughout the procedure , a vacuum - assisted venous drain in the heart - lung machine is used and carbon dioxide is infused into the operative field to decrease the chance of air embolism .
complete evacuation of intracardiac air is performed through the aortic root and left atrium and confirmed by tee .
defibrillation , when necessary , is administered through the external defibrillator pads . once the hemodynamic status is stable , cardiopulmonary bypass is discontinued and decannulation is performed .
transesophageal echocardiography is mandatory at the moment to document the repair results or prosthetic function .
the right pleural space and mediastinum are drained through the 7 intercostal space with two chest tubes and the intercostal spaces are closed with five or six pericostal sutures .
this simplified minimally invasive approach to mitral valve surgery with optimal access to all cardiac structures and optimal exposure of the mitral valve under direct vision offers distinct advantages , including direct aortic root and caval cannulation performed with ease and without obscuring the operative field , optimal exposure and overview of the operative field , controlled myocardial protection , and adequate de - airing .
although the skin incision is 5 - 8  cm longer than in the conventional minimally invasive technique , besides providing good cosmesis and an acceptable postoperative scar , it outweighs the placement of additional skin incisions for the other cannulae or the aortic clamp , and obviously avoids the potential complications related to femoral vessel cannulation .
additionally , standard aortic cross - clamping and antegrade cardioplegia delivery obviate the need for specialized endovascular occlusive balloons , hence avoiding the potential complications associated with balloon malposition or migration .
this simplified approach combines good cosmesis with optimal exposure of the mitral valve and all the cardiac structures , is readily applicable and is not associated with a steep learning curve because one employs conventional cannulation and clamping techniques .
 with increasing enthusiasm in minimally invasive surgery , several approaches and access are being performed with great precision . in this report , we illustrate and describe a minimal invasive approach to mitral valve surgery with optimal access under direct vision , the indications and patient selection , the surgical techniques , its advantages over the other approaches , and its simplicity and reproducibility . 
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