Variation for Cardiac Transplantation in Adults with Congenital Heart Disease
21.2 Right Atrial Technique
The right atrial technique, which was the original technique described by Lower and Shumway for patients with end-stage ventricular failure from dilated cardiomyopathy, has largely been abandoned and is used only in specialized situations in which there is complex systemic venous return to the right atrium. The principal anomalies include left superior caval vein to the coronary sinus, or right atrial entry of one or more hepatic veins. It makes no sense to individually re-anastomose these anomalous systemic veins to the donor right atrium; it is better to leave them in place and use the right atrial technique. Figure 21.2 illustrates the exposed mediastinum of a patient who has had the heart removed in preparation for orthotopic heart transplantation using the right atrial technique. Aortic cannulation is distal on the aorta just adjacent to the innominate artery. This allows room for the aortic cross-clamp and a portion of the aorta for the anastomosis. Venous cannulation has been accomplished with a transatrial approach into the superior caval vein and the inferior caval vein, as shown. Caval snares have been deployed. The pulmonaryartery is divided at the level of the pulmonary valve, preserving as much of the main pulmonary artery as possible. This is especially important if the donor operation involves resection of both lungs for lung transplantation, as there is usually very little main pulmonary artery left on the donor. The superior portion of the right atrium is excised, leaving an opening for the anastomosis as illustrated. Finally, the atrial septum is entered, usually at the site of the patent foramen ovale or fossa ovalis. An encircling left atriotomy is performed, removing the recipient left atrial appendage. This leaves the four pulmonary veins exposed posteriorly with an appropriately sized cuff of left atrium. The donor heart is then brought into the field.
The donor heartis first prepared by connecting the left pulmonary veins and excising excess left atrial tissue. The superior caval vein is ligated and an incision is made from the inferior caval vein orifice to the middle of the right atrium. It is important that the left atrium be kept as small as possible so that there is no excess left atrial tissue once an anastomosis is completed. The anastomosis sequence is left atrium, aorta, right atrium, and pulmonary artery. The left atrial anastomosis is aligned by placing the left atrial appendage of the donor in the normal anatomic site for the left atrial appendage with relationship to the recipient left atrium, typically at the midportion of the left upper pulmonary vein. The left atrial anastomosis is performed with a running polypropylene suture. A vent is placed through the tip of the donor’s left atrial appendage. This vent should be passed into the left atrium and across the mitral valve and is positioned prior to completing the left atrial anastomosis. Cold saline can be infused through the vent while the other anastomoses are being performed, and it can be used to evacuate air from the heart. Alternatively, the vent can be placed in the right superior pulmonary vein. Next, the aortic anastomosis is performed with running polypropylene suture technique. The cold saline is used to de-air the ventricle. Once the aortic anastomosis is completed and the aortic cross-clamp is removed, the patient is warmed. Typically, we would have cooled the patient to 28 °C unless complex arch reconstruction is necessary. Next, the right atrial anastomosis is performed with running polypropylene sutures (Fig. 21.3). Finally, the pulmonary artery anastomosis is performed with running polypropylene sutures. The patient is fully warmed and ventilated. The vent is removed and the patient is weaned from cardiopulmonary bypass. The completed implantation of the heart using a biatrialstrategy is shown in Fig. 21.4.
Currently, the biatrial implantation technique is not generally used owing to acquired tricuspid valve regurgitation and atrial arrhythmias from competing sinoatrial nodes. Many cases of congenital heart disease involve anomalous venous return, such as direct drainage of hepatic veins to the right atrium. Under these conditions, it is better not to use the biatrial technique and not to insist on separate anastomotic suture lines in multiple venous structures.
21.3 Bicaval Technique
Figure 21.5 illustrates the recipient mediastinum following cardiectomy for a bicaval strategy. The cannulation of the recipient is different than with a right atrial technique. The inferior caval vein is cannulated very low, adjacent to the diaphragm. The superior caval vein is cannulated with a right-angle cannula at the junction of the superior caval vein with the innominate vein. The cardiectomy is performed by first transecting the superior caval vein and inferior caval vein. The ascending aorta and main pulmonary artery are transected just below the sinotubular junction. The interatrial groove is developed. Encircling left atriotomy is performed; the result is seen in Fig. 21.5. The completed bicaval technique implant is shown in Fig. 21.6. Figure 21.6 also demonstrates the ligated left atrial appendage, which was used for cold saline cavitary infusion and left ventricular drainage. The sequence of anastomoses is slightly different than for the right atrial technique: the left atrial anastomosis is performed first, followed by connections to the inferior caval vein, aorta, pulmonary artery, and ultimately, the superior caval vein. The alignment is facilitated by placing the left atrial appendage of the donor heart at the site of the recipient left upper pulmonary vein. A vent can then be placed through the tip of the left atrial appendage into the left ventricle so that cold saline can be infused to cool the heart and evacuate air. The rest of the anastomosis can proceed as noted, making sure that all the air maneuvers are performed before releasing the aortic cross-clamp.
21.4 Cardiac Transplantation for Adult Patients with Extant Fontan Connections
For adult patients who have had previous Fontan operations, there are multiple anatomic venous to pulmonary artery connections that challenge the implantation techniques. In particular, these patients do not have a main pulmonary artery. Cavopulmonary artery anastomoses can be unilateral or bilateral. Dextrocardia with inverse connections significantly challenges the classic transplant connections. This section addresses the anatomic variables of extant Fontan connections and their therapeutic and anatomic solutions.
21.4.1 Cardiac Transplantation for Atriopulmonary Fontan Connections
The classic atriopulmonary Fontan connection for patients with functionally single ventricle is rarely used today. Similarly, connections of the right atrium to the diminutive right ventricle (Bjork modification) are also rarely used. Nevertheless, there are long-term patients with these connections who have done well up to the time when they experienced failure of the Fontan circulation, which was complicated by arrhythmias, protein-losing enteropathy, ventricular dysfunction, atrioventricular valvar regurgitation, or other complications. In many respects, these patients have the most favorable anatomy for orthotopic cardiac transplantation because most of the main pulmonary artery of the recipient is preserved, requiring a more extensive preservation of the donor pulmonary artery to complete the anastomosis. This necessitates an anastomosis of the main pulmonary artery of the donor to the confluence of the left and central pulmonary arteries in the recipient. In addition, there are no distal pulmonary artery extant cavopulmonary anastomoses; in most cases, the cardiac orientation is levocardia with normal venous connections rather than dextrocardia, which is discussed below.
If the patient has had stents placed in the left or right pulmonary arteries, the operation is facilitated by harvesting the donor branch pulmonary arteries and performing separate pulmonary artery anastomoses at the hilum after stent removal. When we have used this strategy, we have employed a running 6-0 or 7-0 Prolene suture for these anastomoses, which require careful attention to suture placement to avoid strictures. An alternative technique for the very complex patient is to use a pulmonary valve homograft from another donor, which has been cryopreserved; this graft can be sutured to the hilum of both the right and left branch pulmonary arteries, even prior to the arrival of the donor heart.
Except for the potential complications of mediastinal reentry and modified pulmonary artery anatomy, cardiectomy and cardiac transplantation can proceed in the usual fashion. The choice of right atrial versus bicaval techniquesdepends on the complexity of systemic venous return, as previously discussed.
21.4.2 Cardiac Transplantation for Cavopulmonary Artery Extracardiac and Lateral Tunnel Fontan Connections
The transformation from atriopulmonary Fontan connections to cavopulmonary artery connections is almost complete. The two main anatomic configurations include the extracardiac total cavopulmonary artery connection and the lateral tunnel total cavopulmonary artery connection. There are variations on these two anatomic themes, but none are materially different from their prior configurations.
Basically, these two techniques of total cavopulmonary artery connections involve direct anastomoses of the superior caval vein to the pulmonary artery. In the case of the extracardiac connection, the inferior caval vein is connected directly to the pulmonary artery using an extracardiac tube. In the case of the lateraltunnel connection, the inferior caval vein is connected to the pulmonary artery via an intra-atrial tunnel. Whatever the extant situs solitus Fontan connections, cardiac transplantation can be accomplished using bicaval techniques. Situs inversus anatomy is another matter and is discussed below. In general, the superior caval vein is removed from the superior portion of the right pulmonary artery, and then patch pulmonary artery arterioplasty is performed before cardiac implantation. The inferior caval vein is prepared by disconnection from the inferior portion of the right pulmonary artery, followed by oversewing a retained portion of the connection that does not require pulmonary artery arterioplasty. Alternatively, the donor heart can be harvested with a right pulmonary artery extension to allow end-to-end pulmonary artery anastomosis at the right hilum.
21.4.3 Cardiac Transplantation for Bilateral Superior Cavopulmonary Artery Connections (Bilateral Bidirectional Glenn Shunt)
Intrepid surgeons developed the useof the Glenn shunt for palliation of tetralogy of Fallot and eventually a bidirectional Glenn shunt as an intermediate stage toward total cavopulmonary artery connection (Fontan connections). When anatomic variation presents with bilateral superior caval veins, the operation morphed to bilateral bidirectional Glenn shunts when single-ventricle patients presented for staged total cavopulmonary connections (Fontan operation). These connections are optimal for anatomic and physiologic considerations regarding Fontan physiology, but they represent significant challenges for conversion to cardiac transplantation later in life. Figure 21.7 depicts a patient with extracardiac cavopulmonary artery connections presenting for cardiac transplantation. Obviously, the superior caval veins require unobstructed and tension-free anastomoses for proper systemic venous return and maintenance of cardiac output. One solution to this anatomic dilemma is to harvest an extended donor superior caval vein with the right and left attached brachiocephalic veins, as seen in Fig. 21.8. The donor superior caval vein will have two orifices where the right and left caval veins can be connected (Fig. 21.8). We prefer interrupted suture technique for venous anastomoses to prevent stenosis of the suture lines.