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MMCTS
(January 22, 2009). doi:10.1510/mmcts.2008.003350 Copyright © 2009 European Association for Cardio-thoracic Surgery Procedure Minimally invasive mitral valve surgery via right minithoracotomy
a CNR Institute of Clinical Physiology, Fondazione Gabriele Monasterio, ‘G. Pasquinucci’ Heart Hospital, Via Aurelia Sud, 54100 Massa, Italy * Corresponding author: Tel.: +39-0585-493604; fax: +39-0585-493614. glauber{at}ifc.cnr.it
From early experience in cardiac surgery on the mitral valve, access was gained in different ways: through left and right antero–lateral extended thoracotomy for closed and correspondingly for open mitral commissurotomy, from right parasternal access with rib resection, and via median sternotomy. Median sternotomy remains the most common approach for mitral valve procedures, such as replacement or repair, allowing good visualisation, exposure and working field. Applying the largely spread access as median sternotomy, surgeons always wanted to overcome the necessity of large incisions, get a better surgical view, to dissect with better respect to structural integrity and have better aesthetic results. Enhanced understanding of surgical bases and technological development sourced a breakthrough in minimally-invasive approach for mitral valve surgery, offering several advantages such as less postoperative pain, lower morbidity and mortality, faster recovery and shorter hospital stay. In an effort to share the institutional experience in less invasive surgery, this article demonstrates our approach in mitral valve repair through a right minithoracotomy in the 3rd or 4th intercostal space.
Key Words: Minimally invasive • Mitral valve disease • Right minithoracotomy
Median sternotomy is a standard approach for the repair or replacement of cardiac valves. During recent years, since several reports have been published detailing less invasive techniques for cardiothoracic surgical procedures designed to limit surgical trauma while decreasing costs, the new era of cardiac valve repair and replacement was inaugurated and minimally invasive techniques have gained popularity in all cardiac valvular procedures [1, 2, 3]. Those reported surgical approaches described particular techniques for access and exposure, such as the right thoracotomy access and femoral cannulation techniques for establishing the cardiopulmonary bypass [1, 2, 3, 4, 5, 6]. In this work we would like to illustrate our technique on mitral valve repair through a right antero–lateral minithoracotomy.
Anaesthesia Anaesthesia is provided according to the standard protocol used for a conventional mitral valve repair or replacement. The operation is performed under general intravenous anaesthesia. When all necessary arterial and venous lines are acquired the patient is intubated and anaesthetised. We usually use a single lumen normal tube for intubation. A double lumen endotracheal tube can be used for single (left) lung ventilation if some difficulties during preparation are expected. Pleural adhesions in case of reoperation, chest profile and unfavourable intrathoracic working plane that can cause poor visualisation of the ascending aortic cannulation site could be reasons for double lumen tube insertion. Transoesoephageal echocardiography (TOE) probe is positioned to obtain a clear anatomic image of the mitral valve and its functional morphology, monitor the venous cannula correct insertion/placement and to evaluate the valve function pre- and postoperatively. Two defibrillator pads are accurately placed across the chest wall to guarantee an effective electric conduction. The patient is in a supine position and an air sack is placed under the right scapulae, to allow the patient's right chest to be elevated slightly according to the need of the surgeon for a better working field exposure. This can be useful, particularly in patients with deep chest. This sack can be pumped enough to lift the right chest upward or downward if air is removed. Patient's right arm should be deviated slightly from the body, this permits having enough space for the placement of the working ports (Photo 1).
Afterwards, the patient is prepared with iodine solution according to established intra-operative protocol. The patient is draped exposing the anterior and right lateral chest wall and both groin areas. An adhesive aseptic strip is then applied to the exposed areas, thus minimising the possible risk of contamination.
A 5-Fr catheter introducer sheath is placed percutaneously in the right femoral vein. This is made before the incision, to have any possible femoral artery punctures before heparin administration. A prepared right femoral vein introducer sheath permits direct venous cannula insertion without any delay, when the patient is anticoagulated. Femoral vein should be punctured at 6–8 cm lower than inguinal ligament line. This permits a straighter introduction of the venous cannula into the right femoral vein. The procedure is carried out through a 6–7 cm incision in the 3rd or 4th intercostal space. The length of the incision is not the primary goal for those surgeons who start with this approach, and can be made smaller with further experience. The right minithoracotomy is made such that the middle part of the incision is positioned in the anterior axillary line. We have started with a more anterior incision at the beginning, for an additional confidence during aortic cannula placement and removal. Then, with more experience, we gradually switched to a more lateral, submammary incision in almost all patients, which gives better visualisation of the field and perfect valve exposure (Video 1).
Once the thoracotomy is made, two auxiliary working ports are established. One 5.5-mm working port is used for a video assistance and for passing the pericardial stay sutures. We prefer to use the same port to avoid further risk of intercostal arteries injury. The port is placed in the same intercostal space, in the mid-axillary line where the thoracotomy incision is made. Another 10.5 mm port is placed two intercostal spaces lower in the mid-axillary line. This port is used for the cardiotomy vent, CO2 insufflation and for other pericardial stay sutures. The soft tissue retractor and a reusable atrial retractor (Photo 2) (MMCTSLink 131) are used to expose the working field (Video 2).
Video assistance gives excellent illumination and serves as an important tool for the first operator and for the surgical team. The pericardium is opened up and down from the diaphragm to the ascending aorta, keeping the incision approximately 3–4 cm above the phrenic nerve. When the pericardium is opened, two 2-0 silk stay sutures are placed on each margin; the aorta is then exposed and two aortic purse strings for direct arterial cannulation are placed into the ascending aorta in a standard fashion (Video 3).
Once the purse strings on the ascending aorta are ready, preparation is commenced on the groin. Using the Seldinger technique, the guidewire is passed through the introducer sheath and under TOE guidance is introduced into the superior vena cava. Sheath is removed; dedicated venous cannula dilators are essential in tunnelling the cannula path. Then the venous cannula can be easily introduced and advanced over the guidewire until its final position in the superior vena cava. The most informative TOE projection is the bicaval view at 120° (Video 4).
We use different cannulas for aortic cannulation, based on the patient's body surface area, thoracic conformation and/or surgeon's individual choice. We apply a double-stage venous cannula if concomitant tricuspid valve repair is planned. These are some of the cannulas that we use in our practice: 23-Fr StraightShot® aortic cannula, 22, 25-Fr QuickDraw® venous cannula (Cardiovations, Edwards Life-sciences, Irvine, CA – MMCTSLink 132); 19, 21, 23, 25-Fr Biomedicus® venous cannula (Medtronic, Minneapolis, MN – MMCTSLink 177); 21-Fr EasyFlow® aortic and double-stage 22-22-Fr and 23–25-Fr venous cannula (Estech, San Ramon, CA – MMCTSLink 178). In this presented case the ascending aorta is cannulated under direct vision using a StraightShot tip-mounted, self-retractable blade aortic cannula, and then fixed with two tourniquets. The additional encircling of the aortic cannula and tourniquets with silk sutures is made similarly to a standard cannulation technique as in median sternotomy (Video 5).
A standard cardioplegia catheter (MMCTSLink 179) is placed in the ascending aorta and the infusion and venting lines are connected as during usual procedure (Video 6).
Intervention proceeds in a conventional manner. The aorta is clamped with a flexible Cygnet® flexible aortic cross-clamp (Photo 3) – MMCTSLink 180.
The rigid shaft of the clamp enables tunnelling and accurate clamp jaws placement. Once properly placed, the rigid shaft retracts leaving a flexible neck, which can be manoeuvred to a place remote from the surgeon's working field. The myocardial protection is initially delivered. Cardioplegia is delivered as a single dose/shot (20 ml/kg) of crystalloid solution (Custodiol) antegradely into the aortic root. The cardioplegia delivery and aortic valve competence is controlled by TOE (Video 7). The temperature during cardiopulmonary bypass is maintained at 34 °C.
Properly retracted pericardium gives a perfect view of the operative field: when proper myocardial standstill is established, dissection is made in Sondergaard's plane. The special atrial retractor is applied and the mitral valve exposed (Photo 4, Video 8).
As mentioned above, the 10.5-mm port is used for CO2 gas insufflation and afterwards also for cardiotomy suction. Carbon dioxide is used to fill the pleural cavity because of its high solubility. Any residual air in the left side of the heart following the procedure is therefore easily absorbed, thereby minimizing the risk of air embolism. The port is connected to CO2 gas, which runs at 0.5–1 l/min. The intrathoracic CO2 concentration reduces the amount of retained intracardiac gas. When the mitral valve is exposed its analysis is carried out. Once the type of repair is decided, the surgeon can proceed with initial suture placement on the mitral valve annulus (Video 9).
Reductive annuloplasty of the mitral valve is performed following a standard technique. After placement of all necessary sutures with 2-0 synthetic braided sutures, the valve is inspected again with hooks and by water probe (Video 10).
The mitral annulus diameter is measured using dedicated valve sizers. Sutures are passed through the mitral ring, knotted with a knot pusher and excised. The implanted mitral ring is carefully controlled by the surgeon. Water probe is applied again to confirm the valve competence with a lowered open mitral ring (Videos 11 and 12).
We used the C-G Future Band Mitral Annuloplasty Ring in this case (MMCTSLink 181). During mitral valve repair procedure, air may be entrained into the left atrium and ventricle, and the aorta. When the mitral valve competence is checked, a left ventricular vent is positioned through the mitral valve and left atriotomy is closed. The residual air is aspirated by both the aortic root and the ventricular vents (Video 13).
The lungs are inflated, the heart is filled by blood, and the cross-clamp is fully removed. Subsequently, when complete de-airing is confirmed by TOE, the ventricular vent is removed. After rewarming the patient is weaned from CPB. The aortic cannula is removed. The cannula insertion site is then controlled for bleeding and reinforced with pledgeted sutures if necessary (Video 14).
Subsequently, the venous cannula is removed after heparin has been reversed with protamine. We remove the venous cannula only after heparin has been reversed, because of percutaneous approach in venous return cannula insertion. After venous cannula removal, the projection of the femoral vein is temporarily placed under compression, skin defect is closed (Video 15). Usually, it is enough to let the venous defect be closed without significant blood loss and any additional manipulations.
Haemostasis is secured; two 24-Fr BLAKE chest drains are placed through the 5.5-mm and 10.5-mm ports site (MMCTSLink 182). The pericardium is closed with 2–3 single polypropylene sutures. The minithoracotomy incision is then closed in anatomical layers. Skin is approximated in a traditional manner with intradermic absorbable sutures; the minimally invasive access site of 7 cm length is closed (Video 16).
Minimally invasive mitral valve procedures through a right minithoracotomy were initiated in our department from November 2003. Presently we perform this procedure in all patients with an isolated mitral valve disease. We use this approach also for concomitant tricuspid valve repair. Principally, there are no contraindications to this kind of procedure. Those patients with indications for combined aortic valve replacement and/or myocardial revascularisation are candidates for sternotomy approach. Previous surgery on ascending aorta and right thorax are other contraindications to this approach. Until March 2008, mitral valve surgery in minithoracotomy was performed in 750 patients with a mean age of 61.3±13.7 years. In 596 (79.4%) patients mitral valve was repaired, whereas in the other 154 patients (20.6%) mitral valve was replaced. Mean CPB time was 126±44 min; mean cross-clamp time 83±25 mean operation time 242±51 min. A group of 29 (3.8%) patients underwent revision for bleeding. Aortic dissection was observed in 2 (0.1%) patients. Conversion to sternotomy was made in 5 (0.6%) patients because of bleeding and aortic root discontinuity. Postoperative mortality was in 9 (1.2%) patients. Mean ICU length of stay was 7.4±5.8 days; 81% of patients were discharged from ICU in <24 h. Patients undergoing this kind of intervention are usually ready to be discharged from our department within one week. Postoperative aesthetic appearance of the wounds was satisfactory.
Several reports of minimally invasive valve operations have been published during the last decade [1, 2, 3, 4, 5, 6, 7, 8, 9]. The described surgical technique via a right minithoracotomy in the 3rd and 4th intercostal space and application of custom-made armamentarium (Photo 5) (MMCTSLink 183) gives an excellent mitral valve exposure and working field. This approach permits to treat patients with less invasiveness and better cosmetic results. Patients have less postoperative pain and shorter hospital stay.
Mitral valve repair or replacement in right minithoracotomy is still in its development. Since the Heart Access surgery was adopted as a treatment of choice, various technical details of this approach have been changed and upgraded. Complete femoral cannulation via open access is transformed to direct aortic cannulation and percutaneous venous return cannula insertion. Specialized balloon-tipped endo-aortic cross-clamp could be replaced by direct cross-clamping technique. Surgeons have the possibility to select devices and instruments, and surgical technique according to their own preferences. This approach becomes more reproducible for all surgeons, being based on their conventional hand skills. In our department, we are currently performing all isolated mitral valve procedures in right minithoracotomy and applying the same minithoracotomy approach for concomitant tricuspid valve disease and surgical treatment of atrial fibrillation. Our experience with mitral valve repair and replacement through right minithoracotomy demonstrates that minimally invasive mitral valve surgery is a feasible method that can be performed safely and effectively.
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