Aortic valve surgery started with the implantation of the Hufnagel valve in the descending thoracic aorta in 1956. Its evolution over time has culminated with the establishment of percutaneous catheter-based aortic valve replacement techniques. As a new paradigm in aortic valve replacement is ushered, there will be new challenges for the cardiac surgeons to not only maintain the efficacy and outcomes of conventional valve replacement but to provide it in a less invasive approach. Modern techniques will be measured against conventional procedures, especially in the older patients with multiple comorbidities. Minimally invasive aortic valve surgery holds promise as an effective operation with reduced pain, improved respiratory function, early recovery, and an overall reduction in trauma.

Reoperative minimal access aortic valve surgery is discussed in detail at the end of this chapter. We will first outline the known benefits and salient principles of and the essential ingredients for the conduct of primary minimal access aortic valve surgery. There are many potential benefits of minimal access aortic valve surgery:

1. 
   

   It provides a cosmetically superior incision

   
   
2. 
   

   There is reduced postoperative pain

   
   
3. 
   

   There is faster postoperative recovery

   
   
4. 
   

   There is improved postoperative respiratory function from preservation of a part of the sternum and the integrity of the costal margin

   
   
5. 
   

   It can be performed with the same degree of ease and speed as a conventional operation with no difference in mortality

   
   
6. 
   

   It provides access to the relevant parts of the heart and reduces dissection of other areas

   
   
7. 
   

   It greatly facilitates a reoperation at a later date as the lower part of the pericardium remains closed.

There are some salient inviolate principles of minimal access aortic valve surgery:

1. 
   

   Ability to safely apply a stable aortic cross-clamp

   
   
2. 
   

   Ability to visualize the aortic valve completely and perform a successful replacement with the standard techniques

   
   
3. 
   

   Ability to achieve the same degree of myocardial protection as through a midline sternotomy approach

   
   
4. 
   

   Ability to deal with issues of the aortic root, ascending and arch of the aorta with relative ease and without the need for conversion

   
   
5. 
   

   Ability to quickly convert to a standard midline sternotomy if compromising situations arise

The safety and reproducibility of minimal access aortic valve surgery depend on:

1. 
   

   Availability of experienced cardiac anesthesiologists

   
   
2. 
   

   Availability of transesophageal echocardiography (TEE) in every case and an experienced echocardiographer to interpret findings

   
   
3. 
   

   Ability to place pulmonary artery catheters with pacing capabilities and transjugular coronary sinus catheters, if and when necessary

   
   
4. 
   

   Ability to place percutaneous arterial and venous cardiopulmonary bypass canulae

   
   
5. 
   

   Ability to use vacuum-assisted venous drainage on cardiopulmonary bypass

   
   
6. 
   

   Availability of minimal access retractors and other relevant instruments that facilitate this operation

   
   
7. 
   

   Ability to remotely monitor myocardial protection and distention by TEE

   
   
8. 
   

   Availability of surgeons experienced with conventional aortic valve surgery and minimal access surgery.

Whatever the surgical approach, today aortic valve replacement is done with the use of cardiopulmonary bypass and diastolic arrest of the heart. There are at least four different minimal access surgical approaches to the aortic valve:

1. 
   

   Upper hemisternotomy

   
   
2. 
   

   Right parasternal approach

   
   
3. 
   

   Right anterior thoracotomy

   
   
4. 
   

   Transverse sternotomy

The Upper Hemisternotomy Approach

This is undoubtedly the most popular of all minimal access approaches to the aortic valve.^1,2 This is performed through a 6- to 8-cm vertical midline incision over the upper part of the sternum, starting at or just above the level of the manubrio-sternal angle. The sternotomy is performed with the standard saw starting at the level of the sternal notch up to the level of the third or fourth intercostal space (Fig. 32-1). The sternotomy is then T’d off into the right or left third or fourth intercostal space using a narrow blade oscillating saw, taking care not to dive too deeply with it for risk of injuring mediastinal or pericardial structures. The decision to T into the third or fourth space can be made preoperatively with the chest x-ray being a guide to the amount of exposure that will be needed. We favor the fourth interspace because this almost always produces the ideal exposure. It is very important to ensure that the sternotomy is absolutely midline and that the midline sternotomy is not carried beyond the level of the transverse T. Failure to adhere to these principles will result in either a lateral fracture with resultant three sternal fragments or a continued lower extension of midline fracture which with retraction could result in a slow ongoing intraoperative or postoperative blood loss and also difficulty in closure. There is no need to prophylactically divide the right or left internal mammary arteries with this incision. If care is taken not to damage them, they will usually gently retract away.

A small-blade retractor spreads the sternum.The pericardium is opened in the midline (Fig. 32-2), T’d inferiorly, and at least three pericardial stay sutures are applied to either side and the needles are left on. The retractor is removed and the pericardium is tacked to the dermis of the skin and tied down. This facilitates exposure by elevating the pericardial contents forward into the operating field. The retractor is then repositioned. Care must be taken during reopening the retractor because sudden retraction with elevated cardiac structures could impede venous return, causing a sudden drop in cardiac output, and leading to acute refractory decompensation in patients with severe aortic stenosis.

We perform an epiaortic ultrasound to exclude atheromatous disease in the ascending aorta before proceeding to systemic heparinization and ascending aortic cannulation in the standard fashion. Right atrial venous cannulation is accomplished directly through the appendage (when easily accessible) (Fig. 32-3) or with a percutaneous venous cannula inserted via the right or left femoral vein. There are a variety of custom long venous canulae that are available for the same (usually 20- or 22-French), and they are inserted using the Seldinger technique. The cannula is positioned within the right atrium with the tip in the superior venacava using transesophageal echocardiographic guidance. The patient is then placed on cardiopulmonary bypass. We use tepid bypass with core cooling to 34 to 35°C. The need for vacuum-assisted venous drainage to facilitate this operation cannot be overemphasized.

A retrograde cardioplegia catheter can be placed in the coronary sinus via the right atrial appendage. This may require a minor adjustment to reduce the angulation of the catheter and its insertion can be facilitated by the use of transesophageal echocardiography. Alternatively, this catheter can be placed by the anesthesiologists before surgical incision via the transjugular route. Although we routinely use a transaortic left ventricular vent, a right superior pulmonary vein or a left atrial dome vent can also be easily placed via this incision.

The operation then proceeds as usual. The aorta is cross-clamped and we use 1 L of 8:1 cold blood antegrade cardioplegia. TEE is used to monitor left ventricular distention in patients who may have aortic insufficiency. Retrograde cardioplegia and additional doses of cardioplegia are administered as necessary. Standard aortic valve replacement is then carried through an oblique aortotomy (Fig. 32-4). Upon completion of the procedure, the patient is rewarmed and the aortotomy is closed. A de-airing needle is placed in the ascending aorta before removal of the aortic cross-clamp.

Almost always the heart recovers spontaneous sinus rhythm. When the heart recovers into ventricular fibrillation, it will need to be defibrillated using the external defibrillator pads placed before commencement of the operation. Defibrillation can be facilitated by turning the cardiopulmonary bypass flows down to decompress the heart and other appropriate pharmacologic maneuvers. It is usually quite difficult to introduce internal defibrillator blades through this incision, although pediatric blades can be placed successfully on occasion. Appropriate preoperative placement of external defibrillator pads are of paramount importance. The heart is de-aired using TEE guidance. In the absence of the ability to reach in and agitate the heart, a combination of ventricular filling, table positioning, and external compression is used to successfully de-air the left heart. Although this can always be successfully completed, patience may be an important tool to facilitate this. It is important remember that successful and complete de-airing does not occur until the blood has begun to circulate through the pulmonary and systemic circuits and the heart has started to eject normally.

Before emergence from bypass, pacing wires and drainage tubes will have to be placed (Fig. 32-5). It is very important to perform these placements with the heart decompressed on bypass so as to prevent injury. Invariably, there is an adequate amount of atrial and ventricular myocardium exposed to place pacing wires. We usually bring these wires out in the right inframammary area through the right-sided T. We place fluted silastic drains from a subxiphoid approach. Small incisions are made in the subxiphoid area and long grabbing forceps are used to make two retrosternal tunnels, one of which will puncture the pericardium to facilitate placement of a pericardial drain and the other will remain in the retrosternal plane. These are placed with a combination of tactile and visual control. In cases in which drains were not placed before separation from bypass and decannulation, we recommend opening the right or left pleural space and placement of transpleural drainage tubes. Placement of subxiphoid drains is not recommended after the heart is full. The wean from cardiopulmonary bypass is then performed in the standard fashion followed by decannulation and protamine administration.