In the operating room, standard monitoring techniques (e.g., central venous line, arterial line, bladder catheter) are used. Swan-Ganz catheter monitoring is useful in high-risk patients with elevated pulmonary pressure or depressed ventricular function. An external defibrillator is placed in mini-invasive surgery, right thoracotomy, and redo operations. A double-lumen endotracheal tube is used in patients undergoing a right thoracotomy approach. CO 2 insufflation (4 L/min) is instituted at least in the last 30 minutes of the intracardiac procedure. Intraoperative transesophageal echocardiography is mandatory in all patients undergoing valve reconstruction to determine the functional type of regurgitation, to evaluate left and right ventricular function, and to detect associated lesions. Post–bypass transesophageal echocardiography is critical to assess the quality of valve reconstruction, to determine the degree and mechanism of occasional residual leaks, to assess ventricular function, and to confirm the complete de-airing of the cardiac cavities.
SURGICAL INSTRUMENTATION
In reconstructive valve surgery, in addition to classic surgical instruments, specific instruments *
* Delacroix-Chevalier, Landanger Group, 9 boulevard de Tassigny, BP 2152, 52906 Chaumont (France).
are useful ( Fig. 4-1 ). In aortic valve surgery, atraumatic aortic retractors are used (a) . In mitral and tricuspid valve surgery, a specifically designed sternal retractor with self-retaining blades to retract the atrial wall provides optimal exposure (b). Nerve hooks are critical for valve analysis (c) . Additional instruments include atraumatic gripping forceps (d), papillary muscle clamp (e) to facilitate papillary muscle exposure, long needle holder with large jaws (f) , and scissors (g) . Suture material requires special consideration. Braided 4-0 sutures are recommended for ring implantation. A ⅜ curvature needle rather than a semicircular needle is strongly recommended to ensure large bites and therefore to prevent ring dehiscence. A resilient polyamide suture material is ideal for leaflet, chordae, and papillary muscle reconstruction. Such suture material has the advantage of being pliable, elastic, and without memory. Importantly, they can be secured with only four knots. For leaflet reconstruction and chordae transfer, 5-0 sutures are used. For annular reconstruction, leaflet reattachment to the annulus, and papillary muscle plasties, 4-0 polyamide sutures with ⅜ curvature needles are used. The widely used polypropylene suture material is less adaptable for valve reconstruction because of its rigidity, sliding characteristics, and protruding knots with sharp ends that can cause leaflet abrasion and impair leaflet coaptation.
SURGICAL APPROACH
Median Sternotomy
Median sternotomy is the preferred approach in patients undergoing valve surgery as well as in the reoperative setting ( Fig. 4-2 ). In this era of less invasive surgery, the 20-cm skin incision, commonly used in the past, is no longer necessary (inset) . A smaller, 8- to 10-cm skin incision is cosmetic and less traumatic, and yet provides adequate exposure to perform a full sternotomy with optimal opening. Special attention should be given to dissection of substernal tissues in order to avoid opening pleural spaces.
Proper positioning of the sternal retractor is obtained by ensuring that the midpoint between the two central anchoring mechanisms is aligned with the right atrial appendage ( Fig. 4-3 ).
Right Anterolateral Thoracotomy
This approach is used in mitral valve surgery for cosmetic reasons or in redo operations ( Fig. 4-4 ). It is contraindicated in patients with previous right-sided chest surgery, moderate to severe aortic regurgitation, or severe chronic obstructive pulmonary disease. The patient is rotated 30 degrees to the left side. A 12- to 15-cm right anterolateral thoracotomy is performed through the fourth intercostal space. A double-lumen endotracheal tube is used to decompress the right lung. Before the patient is draped, an external defibrillator is placed for subsequent defibrillation. The opening of the thorax is limited to the minimal amount required for atrial or superior vena cava cannula- tion. Cannulation of the ascending aorta is possible in most patients.
LESS INVASIVE APPROACHES
Less invasive surgery is attractive because of numerous claimed advantages: better cosmetics, less bleeding, decreased risk of infection, reduced pain, shorter hospital stay. Certain risks have been emphasized, however, such as a higher incidence of stroke. Actually, the main potential disadvantage of less invasive mitral valve surgery is the execution of a suboptimal operation as a result of suboptimal exposure (e.g., a valve replacement instead of a valve repair, a palliative repair technique instead of a reconstructive valve operation). Excellent exposure is a requisite in surgery, in particular in reconstructive valve surgery. The incision may be large or small; the important point is that it provides a good visualization of the different structures of the valve regardless of their depth. Some surgeons with extensive experience in reconstructive surgery have been able to meet this challenge using different less invasive approaches.
Less invasive surgery is attractive for the patient but more demanding for the surgeon. The potential drawback is the execution of a suboptimal operation.
Ministernotomy
Ministernotomy may be used both for aortic and for mitral or tricuspid valve surgery. Two alternatives may be used: The upper ministernotomy ( Fig. 4-5 ) extends from the sternal notch to the third or fourth right intercostal space; it is particularly indicated for aortic valve surgery. The lower ministernotomy ( Fig. 4-6 ) extends from the xyphoid process to the second right intercostal space; it is indicated for mitral and tricuspid valve surgery. Access to the mitral valve is achieved through the interatrial groove or the atrial septum. Cannulation of the ascending aorta is possible, particularly when using the upper ministernotomy. Peripheral arterial cannulation is advisable if access to the ascending aorta is limited or aortic calcifications are present. Venous cannulation is performed either percutaneously, using the right femoral vein and the jugular vein, or directly through the right atrium. Assisted vacuum is essential to facilitate venous drainage.
Right Lateral Minithoracotomy
Right lateral minithoracotomy ( Fig. 4-7 ) was the approach used to perform the very first cases of mini-invasive mitral valve reconstruction. Today, it is used routinely with excellent results by some groups. The incision is limited to 5 cm and a port is placed in the fourth intercostal space. In addition to the aforementioned setup, this approach requires specific instrumentation and video assistance. Computer assistance may be useful and will certainly develop further in the future.
In any one of these less invasive procedures, three recommendations are important: (1) placement of an external defibrillator before draping, (2) placement of ventricular epicardial temporary stimulation leads before the patient is weaned from cardiopulmonary bypass, (3) careful preservation of distal flow to avoid lower extremity ischemia whenever peripheral cannulation is used.
REDO OPERATIONS
The most common scenario of redo operations involves aortic or mitral valve surgery after prior coronary artery bypass grafting. Other scenarios include redo mitral valve surgery, mitral valve surgery after aortic valve replacement, and tricuspid valve surgery after the correction of left-sided valve disease. The rule is to limit dissection as much as possible. To achieve this goal, several approaches may be used depending upon the valve involved and the previous operation.
Median Sternotomy
Median sternotomy is the preferred approach for all valvular procedures, particularly in patients undergoing multiple valve operations. There may be some exceptions, however, such as multiple previous coronary bypass surgeries, recent previous operation, and prior episode of mediastinitis. Repeat sternotomy requires special care to avoid injuries to the right ventricle or the ascending aorta or to the coronary artery bypass grafts. Before the operation, chest computed tomography is useful to visualize the retrosternal space. Coronary angiography allows precise localization of the positions of grafts if they are present. Before the patient is draped, an external defibrillator is placed for occasional defibrillation. In high-risk cases, repeat sternotomy may be preceded by exposure and control of the axillary or femoral vessels should peripheral cannulation become necessary. The sternotomy is extended from the xyphoid process towards the manubrium while exerting traction on the sternal edges as the dissection progresses. All retrosternal adhesions are released before placing the sternal retractor. Conventional aortic cannulation and venous cannulation are usually possible. If significant mediastinal bleeding occurs, the dissection is immediately discontinued, the tension on the sternal tables is released, cannulation of the femoral vessels is undertaken, and cardiopulmonary bypass is instituted, which decompresses the heart and facilitates cardiac dissection and repair. If necessary, profound hypothermia is instituted (20°C) to allow short periods of cardiac arrest. Special attention should be given to patients with associated aortic regurgitation since ventricular fibrillation and/or distension may occur. In this case, the left ventricle should be decompressed as soon as possible using a left ventricular transseptal vent or a left ventricular vent placed through the apex after a small left thoracotomy.
Upper Ministernotomy
The procedure for upper ministernotomy described earlier is useful in redo aortic valve surgery.
Right Anterolateral Thoracotomy
A right anterolateral thoracotomy approach may be preferred in patients with multiple previous coronary artery bypass grafting or in patients with previous mediastinitis who require a mitral valve or tricuspid valve operation.
CARDIOPULMONARY BYPASS AND MYOCARDIAL PROTECTION
In routine operations , cardiopulmonary bypass is instituted between the ascending aorta and both vena cavae ( Fig. 4-8 ). An epi-aortic echocardiography of the ascending aorta is recommended to rule out significant atherosclerotic lesions at the cannulation and cross-clamp sites before cannulation. The vena cavae are snared with tapes to prevent any warm blood from entering the right atrium. Venous return is facilitated by vacuum-assisted drainage.
Myocardial protection is best achieved by cold blood cardioplegia. Warm blood cardioplegia, currently used in coronary surgery, is not recommended in reconstructive valve surgery because the length of the operation may extend over 2 hours.
The aorta is cross-clamped with care. Intermittent antegrade cold blood cardioplegia is delivered through an aortic needle that is connected to the cardioplegia line and to a suction line used for de-airing ( Fig. 4-9 ). Retrograde cardioplegia through the coronary sinus is a useful adjunct, particularly in complex valve reconstruction. Further myocardial protection is obtained by tepid systemic hypothermia between 28° and 30°C and local hypothermia with topical iced saline. It is useful to monitor the myocardial temperature to optimize further delivery of cardioplegia. The myocardial (septal) temperature should be kept below 15°C at all times. In the absence of temperature monitoring, cardioplegia is repeated every 20 minutes in a retrograde and/or antegrade fashion.
