The Technique of the Fontan Procedure with Posterior Right Atrium-Pulmonary Artery Connection

Transcription

1 The Technique of the Fontan Procedure with Posterior Right Atrium-Pulmonary Artery Connection J. Ernest0 Molina, M.D., Yang Wang, M.D., Russell Lucas, M.D., - - and James Moller, M.D. ABSTRACT A detailed technique is described for use of a modified Fontan procedure applicable to transposed as well as nontransposed anatomy. In the modified procedure, the use of circumferential grafting is eliminated, as are the complications arising from an anterior conduit in front of the aorta. Clinical results are reported for 9 young adults undergoing this operation. The construction of a Fontan connection between the right atrium and the pulmonary arteries has usually been done by placing a circumferential prosthetic conduit with a built-in valve in front of the aorta when no transposition exists [l-61. This has several disadvantages, including compression by the sternum due to the length and size of the conduit, particularly in children [7-91. In patients with transposition of the great arteries, the connection can be accomplished directly between the right atrium and the pulmonary artery on the right side and somewhat behind the aorta [lo, 111. This latter type of connection has the advantage of necessitating either no conduit at all or a very short one to reach the pulmonary artery, and avoids the bulk created by a conduit between the sternum and the anterior wall of the ventricle or the aorta. The modification of the Fontan procedure, introduced by Kreutzer and colleagues [6, 101, made it possible to manage all patients requiring a Fontan operation, whether or not there was anatomical transposition, with a direct connection between the right atrium and the pulmonary arteries. This is accomplished by detaching the pulmonary artery from the ventricle and passing it behind the aorta to reach the right atrium. This technique greatly facilitates the creation of a large anastomosis between the right atrium and pulmonary artery and, in many instances, avoids the use of any prosthetic material in the anastomosis. This article presents our experience at the University of Minnesota Hospitals using this modified technique in all patients requiring Fontan procedures, comprising patients with tricuspid atresia or a single ventricle with two atrioventricular valves. Operative Technique Cannulation of the ascending aorta is carried out as usual by placing a catheter in the highest portion of this From the Departments of Surgery, Pediatrics, and Medicine, University of Minnesota Hospitals, Minneapolis, MN. Accepted for publication June 20, Address reprint requests to Dr. Molina, University of Minnesota Hospitals, 420 Delaware St SE, Box 472 Mayo, Minneapolis, MN vessel. Venous cannulation, however, requires that the cannula going to the superior vena cava be placed directly into the vein above the junction with the right atrium. This applies to patients with or without a previous Glenn. The cannula leading to the inferior vena cava should be placed as posteriorly and inferiorly as possible toward the inferior vena cava entrance, allowing sufficient room for the incision in the anterior wall of the right atrium. The use of cardioplegia is unnecessary, and the heart is kept beating and empty at 32 C with perfusion by the systemic circulation. The ventricular chamber is kept decompressed by placing a sump drain catheter through the right superior pulmonary vein and advancing it into the ventricle across the mitral valve. Intraventricular pressure is monitored by a catheter attached to a sump drain. As the intracavitary pressure is brought below the aortic pressure, the right atrium is safely opened, thereby preventing air embolism. Detachment of the Pulmonary Artery Dissection of the pulmonary artery is usually carried out before the patient is placed on bypass, but if the patient s hemodynamic status is unstable, this can be done while the patient is already on extracorporeal circulation. The main pulmonary artery is dissected off the ascending aorta, as is the right branch that passes behind this vessel (Fig 1). This dissection is carried up to the bifurcation of the pulmonary artery and down to the level of the cusps. The posterior dissection of the pulmonary trunk does not need to be done to the level of the left coronary artery at this time. This is accomplished after the patient is on bypass and the pulmonary artery is already opened. As soon as the ventricle is emptied and the entire pulmonary artery freed, the artery is detached from the ventricle by incising the sinuses circumferentially (Fig 1A). The pulmonary valve orifice in the ventricle is closed with interrupted stitches of nonabsorbable material reinforced with Teflon felt pledgets on either side. We prefer placing stitches at, or slightly below, the insertion of the cusps for maximal strength and to avoid damage to the coronary artery. After this first layer of closure, a running suture can be placed over the everting edges. The pulmonary artery then is passed behind the aorta into the right side of the aorta to meet the right atrium (Fig 1B). The pulmonary trunk is opened on the right side and extended into the right pulmonary artery within 2 mm of the superior vena cava. This incision, however, is placed lower than what appears to be the center of the right pulmonary artery. By making the incision more inferior, the creation of a 371

2 372 The Annals of Thoracic Surgery Vol 39 No 4 April 1985 A Fig 2. The posterior lip anastomosis between the pulmonary artey and the right atrium is done with running suture and a mild amount of tension to prevent formation of an intraluminal shelf between the two structures. The anterior wall of the right atrium is widely opened in a T fashion with the incision lengthened toward the inferior vena cava. The pulmonary valve orifice has been closed. B Fig 1. The pulmona y arte y is dissected off the aorta beyond the artery's bifurcation. (A) The artery is detached from the ventricle with a circumferential incision into the sinuses of Valsalva. (B) The main pulmonary artey then is passed behind the aorta in the transverse sinus to meet the right atrium. posterior shelf that may cause some obstruction to flow is avoided. Handling of the Atrium A direct connection between the pulmonary artery and the atrium has always been possible. This is not accomplished by simple amputation of the right atrial appendage, but by creating a long opening along the edge of the atrial rim extending from the superior vena cava to the tip of the appendage (Fig 2). The incision is made behind this ridge to avoid creation of a posterior obstructive shelf at the time the anastomosis is constructed. Gentle traction is applied to the already open pulmonary artery to assess the level at which the two structures meet, and the incision in the atrium is made at that level. The length of the incision depends on the size of the patient; however, it must provide for a very long and wide opening, which in an adult patient measures approximately 4 to 5 cm. After completing this incision, the anterior wall of the atrium is further opened in a T fashion, starting in the middle of the previous incision, carrying the cut back across the atrium directly toward the inferior vena cava almost parallel to the atrioventricular groove. This provides wide exposure of the inner atrium, and the foramen ovale at that point can be closed. Closure of the foramen ovale probably is one of the most important steps of this operation and should be done very carefully to prevent any type of residual gap between the left and right sides of the heart. At the time of the repair, the heart is decompressed and there is no tension on the septum. After operation, however, the right atrial pressure often is kept elevated to maintain adequate forward flow through the lungs, and if there is any breach or defect in the interatrial septum, a right-toleft will develop, causing severe cyanosis. After the foramen ovale is closed, and if the patient has a single ventricle with two atrioventricular valves, closure of the tricuspid valve is carried out. To accomplish this, good exposure is required and therefore, if necessary, the incision made in the anterior wall of the atrium can be carried all the way down toward the inferior vena cava. Closure of the Tricuspid Orifice The entire tricuspid orifice should be exposed and inspected carefully to decide whether excision of the valve

3 373 Molina et al: Fontan Procedure with Right Atrium-Pulmonary Artery Connection A Fig 4. Completed operation. A triangular serriicircumferential piece of Gore-Tex material has been used to roof the connection between the right atriuni and the pulmonary artery. the same material (see Fig 3). Teflon felt is not used because it is bulky and it shreds. Therefore, we prefer a thinner Dacron material used commonly for intracardiac patching. Positioning of the patch in the subannular level seems to be important, ensuring that with the systemic pressure developed in the ventricle, the patch is actually pressed against the annulus instead of away from it, as will be the case if the patch is placed on the atrial side in the supraannular position. B Fig 3. Closure of the tricuspid orifice. (A) Use of a round piece of grafting material positioned in a subannular fashion. The ventricle is kept decompressed by a sump drain through the right superior pulmonay vein connected to gravity drainage. (B) A reinforcement strip of Dacron material placed on the atrial side is shown in detail. The tricuspid valve has been excised in this instance of a single ventricle with no transposition. is preferable. Closure of the tricuspid orifice is always carried out by using prosthetic material, not the tricuspid leaflets. The method of closure is shown in Figure 3. In our experience, the tricuspid valve had to be resected to attain satisfactory closure. The patch used for this closure is tailored to be slightly smaller than the entire orifice of the valve so that the noncontracting surface of the single ventricular chamber is reduced. The patch is positioned with mattress stitches in a subannular fashion and is reinforced on the atrial side by a long strip of Fontan Connection The posterior suture connecting the pulmonary artery to the right atrium is constructed using a monofilament material. While forming this posterior lip of the anastomosis, both structures are pulled together under light tension to eliminate all types of shelves, folds, or spurs (see Fig 2). This can be done either by plicating while approximating the posterior wall of the atrium to the pulmonary artery, or by resecting more tissue from the atrium. No resection of the pulmonary artery should be done. The anterior wall of the anastomosis then is completed by continuing the suture anteriorly, advancing from each corner toward the center. At this stage, depending on the original size of the atrium, a roof of prosthetic material may be required. If so, a tubular type of Gore-Tex graft is opened on one side and tailored in a triangular fashion to match the size of the anastomosis. This procedure is shown in Figure 4. The anastomosis is created with monofilament suture, and the operation is completed. The heart is allowed to fill, and the patient is removed from cardiopulmonary bypass. Results Nine consecutive patients, 3 to 28 years of age, have been operated on in our institution using this modified

4 374 The Annals of Thoracic Surgery Vol 39 No 4 April 1985 Patients Undergoing Modified Fontan Procedures Pulmonary Arteriolar Patient Pulmonary Artery Resistance No. and Previous Pressure Dynes sec Wood Gore-Tex Age (Yr) Diagnosis Operations (mmhg) Units Operation Roof Single ventricle; PS; L-TGV Single ventricle; PS; L-TGV; single AV valve Single ventricle; PS; D-TGV Single ventricle; PS; D-TGV Tricuspid atresia; ASD Single ventricle; L-TGV Tricuspid atresia; VSD Single ventricle; PS; single AV valve; D-TGV; dextrocardia Single ventricle; PS; ASD None B-T ; Glenn ; Dacron aortopulmonary B-T ; Waterston Glenn ; Fontan procedure with valved conduit; creation of ASD aortosystemic Rashkind procedure; Waterston Pulmonary artery banding; 8-T Rashkind procedure; pulmonary artery banding Two 8-T s; Fontan procedure with bifurcation graft None 27/13 (z) Fontan procedure 32/6 (z) B-T and Dacron s (z) No B-T and Waterston s 28/12 (%) 72 24/14 (T8) /16 (D) /14 (r) /16 (m) Waterston pulmonary artery band and 8-T pulmonary artery band removal of bifurcation conduit; closure of residual ASD Fontan procedure PS = pulmonary stenosis; L-TGV = levotransposition of the great vessels; D-TGV = dextrotransposition of the great vessels; AV = atrioventricular; ASD = atrial septal defect; VSD = ventricular septal defect; B-T = Blalock-Taussig. Fontan technique (Table). Eight of these patients required the use of Gore-Tex material to roof the anterior wall of the connection between the right atrium and the pulmonary artery. No bleeding problems occurred, and no pressure gradients were found to exist between the right atrium and the pulmonary arteries postoperatively. All patients had low pulmonary resistance, and none had prosthetic valves implanted between the right atrium and the pulmonary artery. The operation was very well tolerated by all patients, and no problems ensued at the ventricular closure of the pulmonary valve. The patients have been followed up for periods from 11 months to 5 years 2 months, and none has yet required late implantation of prosthetic valves. Comment The modification of the Fontan procedure, introduced by Kreutzer and colleagues [lo] and Doty s group [ll], is applicable in all patients requiring this type of operation. There is no obstruction to blood flow, and the modified procedure avoids placement of a large circumferential conduit in front of the heart when the

5 375 Molina et al: Fontan Procedure with Right Atrium-Pulmonary Artery Connection vessels are normally related. The simplification of the Fontan procedure avoids the problems related to the placement of woven Dacron conduits that later become obstructed. The amount of artificial material used to obtain an adequate connection is less than half the entire circumference of the anastomosis and, therefore, is not subjected to later occlusion of the anastomosis from all directions. No preclotting is needed, and no compression of the conduit ensues on closing the midline sternotomy incision. The Gore-Tex material offers some rigidity to the diameter of the anastomosis, preventing pinching or compression between the vena cava and the aorta. Therefore, it is our preference to continue to use this modification of the Fontan procedure. Closure of the tricuspid orifice is not done by sewing the tricuspid leaflets, as has been described by Kreutzer and colleagues [6, 101. The reason is that we have observed dehiscence of such a closure, particularly in younger patients. The leaflet tissue may not be strong enough to withstand the pressure of the ventricle, and this may be aggravated by the use of monofilament suture, which is more likely to cut through the tissue and lead to final dehiscence. In addition, if the tricuspid leaflets are used to obliterate the orifice, the surface area, which also constitutes a noncontracting portion of the chamber, can be substantially large. It is also likely that in very young patients, this area will grow along with the ventricle as the child grows. Therefore, we prefer to use patching material, tailored to be slightly smaller than the orifice itself, with the aim of reducing the surface area of this portion. As the heart grows in younger patients, the akinetic area occupied by the patch will become proportionately smaller. Success of the Fontan procedure depends on adequate closure of the atrial septal defect as well as of the tricuspid orifice; therefore, our approach seems to be justified. Creation of the anastomosis between the right atrium and the pulmonary artery following the steps described in this article appears to be safer for assuring a large opening without any tension. Consequently, if there is any doubt that the anterior wall of the anastomosis will be under slight tension, making the connecting orifice flat, one should not hesitate to use the roofing patch of Gore-Tex, as described. With the introduction of Gore- Tex suture material in small sizes, this may be preferable for sewing the patch, since it will prevent the minimal bleeding that always occurs at the needle holes in Gore- Tex when monofilament material is used. References 1. Tatooles CJ, Ardekani RG, Miller RA, Serratto M: Operative repair for tricuspid atresia. Ann Thorac Surg 21:499, Marcelletti C, Mazzera E, Olthof H, et al: Fontan s operation: an expanded horizon. J Thorac Cardiovasc Surg 80: 764, DeLeon SY, Idriss FS, Ilbawi MN, et al: The role of the Glenn in patients undergoing the Fontan operation. J Thorac Cardiovasc Surg 85:669, Uretzky G, Puga FJ, Danielson GK: Modified Fontan procedure in patients with previous ascending aorta-pulmonary artery anastomosis. J Thorac Cardiovasc Surg 85:447, Laks H, Williams WG, Hellenbrand WE, et al: Results of right atrial to right ventricular and right atrial to pulmonary artery conduits for complex congenital heart disease. Ann Surg 192:382, Kreutzer GO, Vargas FJ, Schlichter AJ, et al: Atriopulmonary anastomosis. J Thorac Cardiovasc Surg 83:426, Agarwal KC, Edwards WD, Mair DD, et al: Severe fibrotic obstruction of Hancock conduit after Fontan operations (correspondence). J Thorac Cardiovasc Surg 83:791, Ben-Schachar G, Nicoloff DM, Edwards JE: Separation of neointima from Dacron graft causing obstruction: case following Fontan procedure for tricuspid atresia. J Thorac Cardiovasc Surg 82:268, Mair DD, Fulton RE, Danielson GK: Thrombotic occlusion of Hancock conduit due to severe dehydration after Fontan operation. Mayo Clin Proc 53:397, Kreutzer G, Schlichter A, Laura JP, et al: Univentricular heart with low pulmonary vascular resistance. Arq Bras Cardiol37:301, Doty DB, Marvin WJ Jr, Lauer RM: Modified Fontan procedure: methods to achieve direct anastomosis of right atrium to pulmonary artery. J Thorac Cardiovasc Surg 81:470, 1981