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MMCTS
(November 10, 2006). doi:10.1510/mmcts.2005.001826 Copyright © 2006 European Association for Cardio-thoracic Surgery Procedure Aortic valve replacement through a right minithoracotomyCNR Institute of Clinical Physiology "G.Pasquinucci" Hospital, Via Aurelia Sud, 54100 Massa, Italy * Corresponding author: * Tel.: +39-0585 493 604; fax: +39-0585 493 614 E-mail: glauber{at}ifc.cnr.it
During the last years, minimally-invasive operative techniques have been introduced in cardiac surgery. Many advantages, such as less postoperative pain, lower morbidity and mortality, faster recovery, shorter duration of operation and hospital stay associated with lower costs were described for these new techniques. Minimally invasive cardiac surgery has been developed to offer patients the benefits of open heart operations with decreased pain and limited skin incision. It has been popularized as an alternative to the conventional median sternotomy approach. With its several recognized advantages this technique certainly requires some dedicated skills and experience of surgeons, anesthetists and perfusionists for a successful result. In this article we demonstrate our surgical approach for aortic valve replacement through a right minithoracotomy.
Key Words: Aortic valve replacement • Heart-access surgery • Minimally invasive
Median sternotomy is a standard approach for the repair or replacement of cardiac valves. During recent years, minimally invasive techniques have gained popularity in all surgical disciplines. Several reports have been published recently detailing less invasive techniques for cardiothoracic surgical procedures designed to limit surgical trauma while decreasing costs [1,2,3]. Different surgical approaches are reported, describing particular techniques for access and exposure, such as a longitudinal parasternal minithoracotomy [4], partial upper or lower sternotomy, transverse sternotomy and other original techniques. Many of these reports provide practical technical information, and several have suggested that smaller incisions lessen surgical morbidity. Prospective randomized studies have shown that the proposed advantages of all these incisions include reduced pain and surgical trauma, less bleeding, earlier functional recovery, shorter hospital stay, and reduced cost [5,6,7]. In this article we would like to put an emphasis on the surgical aspect of this procedure and present our technique on aortic valve replacement through a right minithoracotomy using the Port Access System (Heartport–MMCTSLink 129). This technique requires a right straight incision with a mean length of 6–8 cm, through the third intercostal space, which gives a perfect valve exposure and working field to replace the aortic valve without any particular difficulties.
Anesthesia The patient is prepared as usual for a conventional aortic valve replacement. The intervention is performed under general anesthesia. The patient is intubated, and anesthetized. Necessary arterial and venous lines are prepared. A double lumen endotracheal tube can be used for single (left) lung ventilation. Transesoephageal echocardiography (TOE) probe is inserted to assess the aortic valve anatomy, morphology and to evaluate the valve function. Defibrillator pads are properly placed across the chest wall. The patient is positioned supine and an air sack is placed under the right scapulae, to allow the patient's right chest to be positioned upward or downward during the operation according to the need of the surgeon for a better working field exposure. This sack can be pumped enough to lift the right chest upward or downward if air is removed. Then the patient is prepared with iodine solution by the appropriate protocol. The patient is draped exposing the anterior and right lateral chest wall and both groin areas. An adhesive strip is then applied to the exposed areas, thus, minimizing the possible risk of contamination.
The procedure is performed through an incision in the third intercostal space. The right minithoracotomy is made such that the medial angle of incision is positioned just prior to the projection of the right internal mammary artery (RIMA) which is 1.5–2 cm laterally to the sternal edge and lateral angle considering the other mean length of incision of 6–7 cm, which varies in different patients. The 6-cm minithoracotomy working port is prepared. The 5-mm working port is used for a CO2 gas insufflation tube and for the cardiotomy vent. It is placed in the 4th or 5th intercostal space. Additional stay sutures on pericardium could be passed using the same working port for a better exposure. The soft tissue retractor (MMCTSLink 130) and ESTECH retractor (MMCTSLink 131) are used to open the working field (Videos 1 and 2).
Once the pericardium is incised and exposed 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. Femoral vein is cannulated percutaneously (Video 4).
The aorta is cannulated using a StraightShot (MMCTSLink 132) aortic cannula, with a tip-mounted blade, and fixed in a traditional manner with two tourniquets. Additional encircling of the aortic cannula and tourniquets with silk is executed (Video 5).
Intervention proceeds in the usual manner. The left ventricle and aortic vents are installed (Videos 6 and 7).
The 5-mm port is used for CO2 gas insufflation and later 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 3–5 l/min. A high intrathoracic CO2 concentration reduces the amount of retained intracardiac gas. Carbon dioxide may be useful for minimal access cardiac surgery where aortic occlusion is not used and intracardiac repairs are done on the fibrillating heart. A flexible angulated cross-clamp is applied (Video 8); myocardial protection is initially delivered. The cardioplegia delivery is controlled by TOE. Pressure on the aorta has been checked traditionally (Video 9).
Cardioplegia is delivered as a single dose/shot of crystalloid solution (Custodiol) antegradely into the aortic root or selectively into both coronary ostia if there is a significant aortic regurgitation. In cases when we have had a major aortic incompetence we performed a retrograde cardioplegia, inserting the cardioplegia catheter into the coronary sinus through the right atrial appendage, under the TOE guide. The aortic vent catheter is removed after successful cardioplegia solution delivery. The purse string is conserved for deairing procedure after aortotomy closure. The aorta and pulmonary artery are dissected to expose the anterior aortic root to the left coronary artery prior to initiating cardioplegia. After arrest has been achieved, the aorta is opened with a transverse incision approximately 5 mm above the origin of the right coronary artery that may be extended posteriorly to the noncoronary sinus of Valsalva [8] (Video 10).
Morphology of the valve is then inspected. Aortic valve cusps are carefully excised (Video 11).
Thorough decalcification of soft tissue improves seating of the prosthesis, and decreases the incidence of paravalvular leak and dehiscence. Care must be taken to prevent aortic perforation while all calcific deposits are debrided off the aortic wall, particularly at the commissure between the left and noncoronary cusps. Careful use of a scalpel or rongeurs may also be required. After the native valve has been excised, 12–16 double-needle interrupted 2-0 synthetic braided pledgeted sutures are passed through the annulus to be secured later with the prosthesis. The pledgets can be left on the inflow/ventricular side or the outflow/aortic side of the aortic annulus. Placing the pledgets on the inflow side of the annulus allows the placement of a larger prosthesis [9] (Video 12).
The aortic annulus diameter is measured using dedicated valve sizers (Video 13). Sutures are passed through the prosthesis, knotted and excised. The implanted prosthesis is carefully controlled by the surgeon for paravalvular leak and dehiscence (Videos 14, 15 and 16).
Aorta is closed with a double row of synthetic polypropylene sutures reinforced with pledgets (Video 17).
During AVR, air may be entrained into the left atrium and ventricle, and the aorta. This must be removed to prevent potential catastrophic air embolization. Immediately prior to tying the suture of the aortotomy, the heart is allowed to fill, the vent in the superior pulmonary vein is stopped, the lungs are inflated, and the cross-clamp is briefly partially opened. The subsequent influx of blood should expel most air from these cavities out of the partially open aortotomy. Closure of the aortotomy is then completed and the crossclamp is fully removed [8] (Video 18).
The LV vent is then placed on suction to remove any residual air as the heart begins electrical activity. After rewarming the patient is separated from CPB and the venous cannula removed after heparin has been reversed with protamine. The projection of the femoral vein is temporarily placed under compression, skin defect is closed (Video 19).
The aortic cannula is successively removed. The purse string sutures knotted; point of cannula insertion is then reinforced with pledgeted polypropylene sutures (Video 20).
Hemostasis is secured after which the lungs are inflated and one 30-F chest drain is placed through the 5-mm port site. The minithoracotomy incision is then closed in anatomical layers. Care is taken particularly to the medial angle of incision as the RIMA should be routinely checked for any lesion (Video 21).
Skin is approximated in a traditional manner with intradermic absorbable sutures; a minimally invasive access site of 7 cm length incision is closed (Video 22).
Minimally invasive aortic valve replacement through a right minithoracotomy was initiated in our department from January 2005. We perform this procedure only in patients with an isolated aortic valve disease with an indication for valve replacement. Totally, 52 interventions were performed in our department using this kind of approach. Two cases were converted to conventional sternotomy because of bleeding and aortic root discontinuity. In four patients with significant aortic regurgitation the retrograde cardioplegia was performed. There was no mortality related to the minimal incision or to the procedure. Percentage of minimally invasive aortic valve replacements (AVRs) to sternotomy approach in our hospital depends currently on the activity of the first surgeon performing this kind of procedure. In his activity 80% of all isolated AVRs he performs in minithoracotomy, and 20%, respectively, in conventional approach. The quantity of all minimally invasive AVRs in the department is 30% in respect to other AVRs via sternotomy. We expect augmentation of our activity in minimally invasive aortic valve surgery in the future as the number of surgeons performing this kind of procedure will increase. Patients undergoing this kind of intervention are usually ready to be discharged from hospital within one week, but for safety reasons we did not discharge them earlier, even if it seemed to be possible. There was no instability or paradoxical movements of the chest wall in any of the patients. The aesthetic look of the wounds was satisfactory in all patients.
Surgical valve repair or replacement is the current treatment of choice for stenotic or insufficient valve pathologies. Different techniques of aortic valve replacement exist. To the present day a few reports of minimally invasive valve operations have been published. The surgical technique described with a right minithoracotomy in the third intercostal space and the use of specially adapted devices and instruments is giving us a perfect exposure of the aortic root, the aortic valve, the right atrium, and the right superior pulmonary vein, thus allowing appropriate access to direct aortic and percutaneous venous cannulation [9,10,11]. Over the last decade, several studies have demonstrated excellent postoperative outcomes among patients undergoing different minimally invasive approaches for cardiac surgical procedures [5]. Aortic valve replacement can be performed safely through a right minithoracotomy on a routine basis for isolated aortic valve disease.
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