techniques in cardiac transplantation

Progress in

Cardiovascular Diseases VOL XxX11, NO 6 MAY/JUNE 1990

Techniques in Cardiac Transplantation

Craig R. Smith

HISTORICAL DEVELOPMENT

C ARDIAC transplantation was first described by Carrel and Guthrie’ in 1905 in a

heterotopic model that was elegant for its time but years away from clinical application. Devel- opment of orthotopic transplantation is credited to Shumway and Lower, whose innovation was a byproduct of studies in myocardial preservation by topical cooling in a dog model, initially done with the heart resting in a cold solution in situ in the pericardial well. Partly to relieve the tedium of standing beside the animal, an autotransplant model was developed, in which the heart was removed and cooled ex vivo, then replaced. They quickly realized that the autotransplant reimplantation was a major technical challenge. It oc- curred to Shumway to remove the heart from one dog, cool it, and reimplant it in a second animal. The first trial proved this to be immeasurably easier than autotransplantation-the animal not only survived, hut thrived initially. Word of this audacious sacrilege soon leaked out from the animal colony, and the future was born, complete with the prophetic odor of animal rights hysteria.2

Operative technique has changed little since the beginning. Shumway and Lower3 recognized early that systemic and pulmonary venous connec- tions could be simplified with atria1 cuffs, avoid- ing the technical difficulty of caval and pulmonary venous anastomoses. In Debakey’s first series4 he described sewing the right atria1 anastomosis first, but soon joined the majority in beginning with the left atria1 anastomosis.

Barnard is credited with a modification in the right atria1 anastomosis that was said to preserve normal conduction5 by swerving from the IVC orifice anteriorly towards the right atria1 appendage when making the cuff incision in the donor (Fig 1). Shumway and Lower’s original descrip-

tion’ placed the opening in the right atrium of the donor along a line connecting the inferior and superior vena caval orifices parallel to the interatrial groove (Fig 2). In fact, it appears that both of Shumway’s first two patients’ left the operating room (OR) in sinus rhythm, and it is hard to be sure that their later bouts of nodal rhythm would have been avoided using the Barnard incision. Certainly many patients will have episodes of nonsinus rhythm even with the orthodox Barnard approach. Nonetheless, Barnard’s modification is so simple there has been no reason to argue the point.

DONOR CARDIECTOMY

What will be described in a continuous narra- tive is, in fact, usually broken into chapters because of the need to cooperate with procurement teams that are removing other solid organs.’ It is customary for the cardiac team to open the sternum and pericardium, make the final inspection, encircle the great vessels and cavae, and then retire from the table to allow the liver team more room over the epigastrium. The length of the recess depends on the technique and experience of the abdominal teams, and varies from 30 minutes to 3 hours or more. During this time, the cardiac team must remain alertly prepared to carry out a rapid cardiectomy in the event that serious problems develop and they should also help the anesthesiologist, whose experience in the management of brain-dead patients varies greatly.

From the Columbia-Presbyterian Medical Center, New York, NY.

Address reprint requests to Craig R. Smith. MD, The Atchley Pavillion, Columbia-Presbyterian Medical Center, 161 Ft Washington Ave, New York, NY 10032.

0 1990 by W.B. Saunders Company. 0033-0620/90/3206-0001S5.00/0

Progress in Cardiovascular Diseases. Vol XXXII, No 6 (May/June). 1990: pp 383-404 383

CRAIG R. SMITH

Throughout the donor procedure, frequent com- munications with the recipient team are critical to the timing of implantation. In addition to transmitting the findings at the time of final inspection, the recipient team should be notified when the donor team returns to the table, and when the crossclamp is applied, updating the expected return time at each juncture.

After median sternotomy and sternal hemostasis, the thymic remnants are excised and the innominate vein divided or retracted cephalad. The pericardium is opened in the midline and attached to the wound edges or retractor to elevate the heart, and the final assessment of donor suitability is made by carrying out a

Fig 1. Barnard’s depiction of the right atriai incision used in his second patient, drignod to avoid injury to the SA node and atriai conduction system. IReprinted with permissicn.6)

careful inspection. Size smaller than expected, bloody pericardial fluid, grossly reduced contractility, distension, palpable coronary lesions, and gross contusion usually require rejection of the donor. Direct inspection is most important in victims of blunt trauma, especially if an echocar- diogram was not obtained.

The superior vena cava is encircled with two large ligatures, which are left tagged but untied. The aorta and pulmonary artery are separated so that the aorta can be elevated away from the right pulmonary artery with a tape when the crossclamp is applied. The margins of the pulmonary artery are defined enough to allow later division without threat to the left atrium or aorta.

Fig 2. Figure from Btinson and Bhumway’s first report iiiu-

strating the right atrisi incision used initially, which connects the cavai orifices posteriorly along a line parallel to the inter- atriai groove. (Reprinted with permission.‘)

TECHNIQUES IN CARDIAC TRANSPLANT

The inferior vena cava is encircled with a tape at this stage, if the surgeon is accustomed to doing this quickly. Awkward and protracted manipula- tion can induce atria1 fibrillation and begin a potentially serious hemodynamic deterioration long before the abdominal organs are ready for removal. A more cautious approach is to encircle the inferior vena cava at a later stage just before applying the crossclamp. A cannula for administration of cardioplegia is secured in the ascending aorta, and should be placed no more distally than the transverse fat fold in the midascending aorta, so that it remains well out of the way of the anastomosis.

When the cardiac team returns to the table, removal begins with ligation of the superior vena cava, using the previously placed ligatures. The vessel is divided between the ligatures at a later stage, so that attention can be directed towards preventing distension of the heart as the arrest sequence begins. The inferior vena cava (see next paragraph) and right pulmonary veins are divided just before the crossclamp is applied (Fig 3). With the crossclamp in place, 1 liter of cardioplegia is infused, and topical hypothermia is initiated by pouring copious quantities of saline at 4°C into the pericardial well. The left ventricle

385

is observed for any evidence of distension, which can be relieved by passing a finger across the mitral valve from the open right pulmonary veins.

Division of the inferior vena cava involves interaction with liver procurement teams who covet extra length, and prefer to think of the caval-atria1 junction as an intraabdominal structure. The cardiac team can safely send the liver team home with a cuff of right atrium if care is taken to avoid beveling medially too close to the coronary sinus and the AV groove (containing the right coronary artery). The accuracy of this manuever is improved if the liver team will allow gentle application of an atraumatic vascular clamp across the inferior vena cava at the dia- phragm before the vessel is opened.

Several minutes are allowed for delivery of cardioplegia and adequate immersion in cold saline, after which the myocardial temperature will be 10% to 15°C. Arrest should be almost instantaneous, and if it is not, the system should be quickly scanned for errors, such as incomplete application of the crossclamp, aortic valve insuf- ficiency, or line occlusion.

The pericardium is aspirated dry, and the ventricles are elevated to expose the back of the

Fig 3. Donor cardiectomy. The superior vena cava has been ligated, the inferior vena cava and right pulmonary veins have been divided, and the crossclamp applied. Cardiople- gia is being infused through a cannuls in the aortic root. (Re- printed with permission.‘2)

386

heart, allowing division of the remaining pulmonary veins. The superior vena cava (SVC) is divided between ties. With caudad traction on the heart, straddling the great vessels with the fingers of the nondominant hand, the aorta is transected at or beyond the innominate artery (Fig 4). The pulmonary arteries are most conve- niently divided individually just past the bifurcation (Fig 4). Division proximal to the bifurcation may leave very little of what is a short structure to begin with. Once the pulmonary arteries are divided, all that remains are fibrous attachments to the posterior pericardium. Except in the most meticulous donor cardiectomy, after the heart has been removed a wad of tissue remains, connecting the base of the aorta and pulmonary artery branches to the superior rim of the left atrium and the posterior aspect of the SVC. This can be cleaned up as necessary in the recipient operation.

After removal the heart is promptly placed inside sterile plastic bags containing saline at 4OC and is transported in an insulated cooler packed in ice. As previously, it is important to maintain contact with the recipient team and continue to refine the estimated time of arrival in the operating room.

CRAIG R. SMITH

IMPLANTATION

Logistics. Timing plays a unique role in cardiac transplantation, in contrast to other cardiac surgical procedures in which incoordination of the surgical team has less direct impact on ischemic time. In other procedures, the most tangible penalty for delay in transport to the OR, or in preparation and administration of anesthe- sia, is the wrath of the surgeon. In cardiac transplant, if the heart arrives before the recipient is ready to receive it, the delay is added directly onto ischemic time. Supporting person- nel must occasionally be reminded of the similar- ity between 10 minutes wasted moving the patient onto the OR table and 10 minutes wasted searching for the correct prosthesis during a valve replacement with the heart arrested.

Events are coordinated by working backwards from the time the donor heart is expected to arrive in the recipient operating room. At Colum- bia-presbyterian it is assumed that 2 hours will elapse from the time the patient arrives in the operating room to the time the recipient is on bypass and ready for cardiectomy, and at least half that time precedes the incision. For example, if the donor recovery team estimates they will

Fig 4. Donor cardiectomy. Aftor dividing the left pulmonary veins. downward traction on the bare of the heart ax- poser the great arteries on stretch. The aorta, pulmonary arteries. and superior vena cava are divided at their poricardial reflections, or more distally if extra length is necesss ry in a particular recipient. (Reprinted with permlwion.“)

387

arrive at midnight, instructions are given to have the recipient on the OR table at 10 PM.

Surprisingly, timing is easiest to coordinate when the donor and recipient are geographically distant from one another, because air travel time is the most predictable single variable. In New York City, distant procurement has become a rarity, and timing has become much more dependent on the less predictable vagaries of the donor operation, greatest of which, at present, is the experience and technique of the liver procurement team.

Preparation. Arterial monitoring and venous access is the same as that used for routine open heart surgery. At Columbia-Presbyterian a Swan- Ganz catheter is placed in the pulmonary artery through a right internal jugular puncture in all adults and larger adolescents. Gentamycin and Vancomycin are given intravenously after induc- tion. The center of the chest and both inguinal regions are shaved. A standard midline sternotomy is performed and heparin is administered about 30 minutes before the donor heart is expected to arrive.

Cannulation. The cavae are encircled with tapes and an aortic cannula is inserted high in the ascending aorta. Bicaval venous cannulation is accomplished through two pursestrings in the right atrium. The site for insertion of the superior caval cannula is on the lateral aspect of the atrium close to the caval-atria1 junction. The inferior cannula is placed near the IVC-atria1 junction, taking care to leave at least 2 to 3 cm of margin between the pursestring and the cava and between the pursestring and the AV groove at the acute margin.

Partial bypass is begun about 5 minutes before the donor heart is expected to appear, and is converted promptly to total bypass by tightening the caval snares. The patient is cooled to 32°C until the donor heart is in the room, at which point the temperature is reduced to 28°C. On total bypass, the coronary sinus return to the right atrium is vented with a sucker placed through an incision at the base of the right atria1 appendage. The space between the aorta and pulmonary artery is opened sharply, carrying the dissection to the base of the heart and to the right across the aortic root until the flaring base of the right coronary is visible. Nothing further is done until the donor heart is in the operating room.

Recipient cardiectomy. When the donor heart arrives, the recipient aorta is clamped just proximal to the innominate artery, cooling is carried out to 28%, and the great arteries are divided (Fig 5). The aorta is transected with scissors, carefully dividing the band of adventi- tial tissue posteriorly with cautery in such a way as to leave some of this buttressing material on the aorta, but without denuding or entering the right pulmonary artery. After opening the anterior aorta, exposure is improved if the pump sucker is placed across the aortic valve and levered inferiorly by an assistant, which elevates and stretches the posterior wall. After dividing the aorta, a large clamp (Glover clamp) is placed behind the pulmonary artery by the assistant, who elevates the posterior wall with the clamp while elevating the distal outflow tract with forceps. The pulmonary artery is divided across the distal tips of the commisures, leaving small remnants of each commisure behind in the recipient pulmonary artery to serve as convenient markers for orientation of the anastomosis.

The jaws of the Glover clamp are transferred to the aortic outflow tract, grasping a large wad of aorta and right ventricle. This clamp is pulled caudad by the assistant with the left hand, who simultaneously picks up on the left atria1 appendage with forceps in the right hand. This exposes the dome of the left atrium and the superior end of the atria1 septum behind the aorta (Fig 6). Beginning at the right atria1 vent site previously made, the excision proceeds around the base of the right atria1 appendage to the superior end of the septum and enters the left atrium just posterior to the aorta. The incision continues around the base of the left atria1 appendage so that the appendage is removed with the specimen. Once the left atrium is opened, levering caudad with the pump sucker placed across the mitral valve improves posterior exposure. At the base of the left atria1 appendage the incision veers towards the mitral annulus, separating the left atrium from the left ventricle on the atria1 side of the atrioventricular groove, excising the coronary sinus in the process. This incision can be carried all the way to the inferior end of the atria1 septum if the assistant pulls up and to the left on the ventricular edge of the opening as it extends.

Returning attention to the right atrium, the assistant changes the direction of traction on the

CRAIG R. SMITH

Fig 6. Recipient cardiectomy. A schematic illustration

indicating the level of division of the great arteries, which are divided across the tops of the commisures. (Reprinted with permirsion.‘2j

Glover clamp in the aortic outflow tract to pull right atrial-right ventricular groove into the coro- superiorly and to the left, while grasping the nary sinus, curving close to the tricuspid annulus right ventricular side of the atrioventricular to preserve an adequate atria1 cuff around the groove with forceps. This places the right atrium inferior venous cannula. Visualization of this on stretch, and the surgeon can easily follow the area is improved by placing the pump sucker

Fig 6. Recipient cardiectomy. The great arteries have been divided, and the incision in the right atrium is extended to

excise the right atrial appendage and enter the left atrium at the superior end of the interatrial septum, just pooterior to the aortic root. The left atrial incision will be directed across the dome of the left atrium (dotted line) to the baee of the left atrial appendage, which is excised, then follows the atrioventricular groove to the inferior and of the intaratrial septum. (Reprinted with permission.‘2)


deep into the coronary sinus as soon as it is visible, applying traction inferiorly to stretch out the septum and triangle of Koch. Once the coronary sinus is entered from the right atria1 side, all that should remain is the atria1 septum, which is divided anterior to the limbus of the fossa ovalis. If an atria1 septal defect or patent foramen is noted, it can be closed directly at this juncture. Large defects are best closed with donor atrium during anastomosis.

It has been the author’s practice to liberally trim the recipient right atrium, in the belief that reducing the circumference of the right atria1 suture line will reduce stretch on the donor right atrium after implantation. Anastomosis between a gigantic recipient atrium and a thin-walled, normal sized right atrium leaves the donor atrium stretched like a canopy over the cavern below,

389

with at least the theoretical potential for stretch effects on conduction and tricuspid valve func- tion.

Preparation of the Donor Heart

The heart is removed from the transport me- dium and placed promptly in a basin filled with iced saline, where trimming is done with the donor heart submerged in cold saline.

Beginning with the left atrium, the pulmonary vein orifices are connected to convert the structure to a roughly circular cuff (Fig 7). There is almost always an excess of circumference on the donor side of the cuff, so that the uneven edges can be trimmed liberally to achieve the desired dimensions. If the donor surgeon has left the superior vena cava, right pulmonary artery, and left atria1 dome as an adherent mass, trimming

Fig 7. Preparation of the donor heart. The pulmonary vein orifices are connected and excess tissue excised to con-

vert the left atrium to a roughly circular cuff with a circumfer-

ence approximating that of the recipient left atrium. (Reprinted

with permission.“1

1t

JfTl

390 CRAIG R. SMITH

should be done carefully to avoid inadvertant entry into the back of the superior vena cava, adjacent to the orifice of the right superior pulmonary vein.

Rolling the heart over, a curvilinear incision is made from the inferolateral aspect of the inferior vena cava towards the base of the right atria1 appendage (Fig 8). The elliptical opening formed should approximate the size of the recipient’s right atria1 cuff.

The foramen ovale is carefully inspected for patency and is closed securely if even probe- patent, leaving the knot on the right atria1 side. Right-to-left shunting with significant arterial desaturation has been seen during the early postoperative period when this has been ne- glected in patients who have high pulmonary vascular resistance, who can develop markedly elevated right atria1 pressures during the period of adaptation.

Implantation

Left atria1 anastomosis. The donor heart is placed on the chest wall on the assistant’s side with the right ventricle down, the left atrium up, and the great arteries cephalad. In this orientation, the left atria1 appendage is facing the surgeon. The anastomosis begins in the rim of the donor left atrium at a point adjacent to the left atria1 appendage, which is approximated to the recipient atrium at the confluence of the left pulmonary veins (Fig 9). The first few bites are placed before the edges are approximated, then the donor apex is lowered into the pericardium as the suture is pulled up. Exposure thereafter is very dependent on the first assistant. One useful method is to have the first assistant place his left middle finger loosely through the mitral valve, using his index finger to gently splay open the leading edge of the donor’s left atrium as the

Fig 8. Preparation of the donor heart. A curvilinear incision is made extending from the inferior vona ceval orifice towards the right atrial appond-

age, creating a cuff approximating the size of the recipient

right atrium. Theforamen wale is examined and closed if patent. (Rep&ted with pormis- sion.“)

TECHNIQUES IN CARDIAC TRANSPLANT 391

Fig 9. Implantation. left

atrial anastomosis. The first portion of the left atrial anastomosis begins by connecting the

free edge of the donor left atrium (adjacent to the left

atrial appendege) to the recipient left atrium at the confluence of the left pulmonary veins, continuing inferiorly (clockwise) to the inferior end of the interatrial septum. (Rs-

printed with permission.“)

anastomosis proceeds. The pump sucker can be an effective adjunct, used as a prop to lift the ventricles away from the suture line.

The suture line proceeds as a simple running suture, first moving inferiorly and to the right, from the atria1 appendage to the inferior end of the interatrial septum. This portion of the suture line encompasses whatever is left of the recipient coronary sinus, and bleeding can be avoided if bites on the recipient side pass through epicar- dium to insure that coronary sinus remnants are buried in the suture line.

Once the inferior end of the interatrial septum is reached, the other needle is used to complete the superior half of the suture line, continuing counterclockwise to include the interatrial septum (Fig 10). At this point it is advisable to begin assessing the size discrepancy remaining and begin taking up excess tissue with suture placement. This almost always means wider spacing of sutures on the donor side. Large amounts of excess donor tissue can be plicated into the septum or oversewn in a pleat.

Sutures do not have to be placed full thickness through the septum if it is thick, since the septal

suture line will be oversewn by the first half of the right atria1 suture line. Anterior to the foramen ovale sutures should be placed through the thicker tissue of the limbus, to avoid tears in the thin foramen that leave behind the potential for interatrial shunting.

Cardioplegia is given through the aortic root after completion of the left atria1 suture line, using the cardioplegia administration needle inserted during the donor procedure.

Visualization can be difficult at the beginning of the left atria1 suture line and can be impossible with iced saline running freely. Once the lower half of the anastomosis is completed, it is usually possible to begin iced saline irrigation and continue it aggressively (6 L/h). Patients who have substantial bronchial collaterals will dump prodi- gious volumes of blood into the pericardium from the pulmonary artery stump and into the left atrium from the pulmonary veins. Uncontrolled, this produces a significant loss of blood elements from the extracorporeal circuit when iced saline irrigation is in use for topical hypothermia. A cell-saver system will recapture most of this, but a penalty is paid in trauma to blood elements.

CRAIG R. SMITH

Once the patient is cooled to 28°C bypass flow can be reduced by 20% to 3096, which will decrease the loss. Clamping the pulmonary artery will decrease loss by that route, but with a corresponding increase in left atria1 return. Plac- ing a cardiotomy sucker in the left atria1 well captures much of the collateral before it has the opportunity to mix with iced saline.

Right atria1 anastomosis. The right atria1 anastomosis is oriented by stretching the donor superior vena cava cephalad and beginning a running suture at the superior end of the interatrial septum (Fig 11). The needle passes through the free edge of the donor right atrium and through the septum into the recipient right atrium, passing through the superior end of the thick suture line just created in completion of the left atria1 anastomosis. Moving inferiorly, in several large bites the inferior free edge of the donor right atrium is rolled back over the septum. Again, suture placement through the recipient foramen ovale is to be avoided, for the reasons previously discussed. At the inferior end of the septum the free edges of the donor and recipient right atria diverge, and the suture line continues around the circumference anteriorly. Exposure of the inferior corner can be difficult

Fig 10. Implantation, left atrial anastomosis. Aftor the inferior end of the interatrial

reptum is reached, the other needle is used to continue counterclockwise across the dome of the left atrium end down the septum. (Reprinted with per- mirrion.‘*)

and is helped by lateral retraction of the caval cannulae. Once closure has progressed far enough anterior that exposure is easy, the other needle is picked up and the superior corner of the anastomosis completed (Fig 12). The anterior third of the right atrium is left open for completion after crossclamp removal.

Pulmonary artery anastomosis. Rewarming is begun, and the pulmonary artery anastomosis is oriented by placing a 4-O prolene stay suture through the donor and recipient pulmonary arteries on the surgeon’s (right) side at 8 o’clock. The posterior third of the anastomosis is done with a simple running 4-O prolene suture begun at 4 o’clock and carried across to the stay suture (Fig 13). The donor artery is usually divided flush with the bifurcation unless an unusual amount of length or circumference is needed. The habit of spatulating open the bifurcation virtually guaran- tees a large size discrepancy, with excess donor circumference, and in some circumstances sig’nif- icant kinking and partial obstruction of the anastomosis can result when circulation is re- stored. The anterior two thirds of the anastomosis is left open for completion after the crossclamp is removed. The Swan-Ganz catheter is pulled from the recipient right atrium through


Fig 11. Implantation, right atrial anastomosis. The right atrial anastomosis begins by oversewing the posterior free edge of

the right atrial cuff (the edge nearest the donor interatrial septum) to the septal suture line just completed in the left atrium. (Reprinted with permission~‘*j

the right ventricle with a clamp passed retro- grade across the pulmonary and tricuspid valves and is repositioned in the pulmonary artery.

It should be noted that ischemic time can be reduced by 5 to 10 minutes if none of the right-sided suture lines are done before releasing the crossclamp. The only reason not to do so routinely is that exposure of the posterior right atrium and posterior pulmonary artery is more difficult with the heart beating.

Aortic anastomosis. The author usually shortens the recipient aorta in an oblique fashion that removes mostly anterior and right wall, correcting for the natural curvature of the ascending aorta to bring the open circumference into simpler orientation for the anastomosis. The donor aorta is usually divided about halfway between the coronaries and the innominate artery. Since the donor is usually younger than the recipient, and the donor aorta therefore smaller, it is frequently beveled posteriorly slightly to increase the circumference of the free edge. Excessive shortening of the aortae makes the anastomosis more difficult and reduces the mar-

gin for error by increasing tension and by making the posterior wall (inner curvature) more difficult to expose. Excess length is relatively benign, although a very long aorta can promote the development of a kink in the pulmonary artery by rotating the base of the heart counterclockwise.

Size discrepancy almost always exists between donor and recipient aortae. The mismatch can be reduced by beveling the smaller vessel, ideally with the acute angle of the bevel in the posterior wall. In most cases, any remaining discrepancy can be accommodated simply by placing sutures closer together on the side with lesser circumference. The young, healthy aorta of the typical donor is quite elastic and will stretch in this fashion to match a surprisingly large recipient aorta. Truly enormous discrepancy can be acco- modated by making an anterior midline slit in the deficient side, analogous to the “Cheatle slit” used in gastrointestinal surgery, or by obliterat- ing the excess in one or more pleats.

The aortic anastomosis begins on the assistant’s (left) side at 4 o’clock and proceeds across the posterior wall towards the surgeon to about

CRAIG R. SMITH

Fig 12. Implantation, right atrial anastomosis. After completing the inferior corner of the right atrial anastomosis, past the inferior vena cava. the opposite needle is ured to continue anterosuperioriy. leaving the anterior third open until after removal

of the crossclamp. (Reprinted with permission.‘2)

10 o’clock as a simple 4-O prolene running suture, then the other needle of the double-ended suture is used to complete the remaining circumference in the opposite direction (Fig 14). Air evacuation is begun by encouraging slow passive backfilling of the left ventricle. Since the left atrium is closed, by the time the aortic anastomosis is begun the left ventricle is usually full, and just enough blood is aspirated from the donor ascending aorta to allow visualization of the suture line. In some cases there will be enough passive flow through the coronaries at this stage to produce a few contractions, but this is preferrable to leaving a large amount of air behind in the left ventricle. As the anterior portion of the anastomosis is completed, the aortic root is flushed with cardioplegia delivered through the needle still in place in the donor to further evacuate air from the ascending aorta.

As the crossclamp is removed, the cardioplegia needle is placed on suction to evacuate air and the right coronary sinus is pinched shut for a few moments to prevent air from entering the right coronary. The anterior two thirds of the pulmonary artery anastomosis is completed as the heart recovers, almost always assisted by isoproterenol and dopamine infusions.

As the right atria1 anastomosis is completed,

the caval tapes are released and the volume of blood in the patient adjusted by the perfusionist to prevent distension of the right ventricle. Ma- neuvers for the evacuation of air are completed, including vigorous massage of the left atrium. The ventricles are retracted out of the pericardium and towards the surgeon to inspect the left atria1 suture line for hemostasis. This manuever will frequently dislodge air that has presumably been sitting in the left ventricle. The aortic root air vent is not removed until the ventricles have been actively ejecting on partial bypass for several minutes without evidence of air escaping from the vent. If air has not been completely evacuated it will usually appear in the right coronary artery as chains of slow moving “box cars,” with corresponding areas of right ventricular dysfunction. Treatment includes massage and rest on bypass with high perfusion pressures and the ill effects are usually quite reversible.

Separation from bypass. The technical satis- factions of cardiectomy and implantion not with- standing, the moment of truth in this procedure occurs when it is time to separate the patient from bypass. A flawless technical performance does not guarantee success, because the acute behavior of a donor heart placed in a diseased circulation following a period of profound hypo-


Fig 13. Implantation. great arteries. The pulmonary artery

anastomosis is ordinarily begun with the crossclamp still in pkce and joins the posterior

thirds of the vessels with continuous suture. The anterior portion is completed with the opposite needle after removal

of the crossclamp. (Reprinted with permission.‘*)

thermic ischemia is not entirely predictable. Quite frequently the right atrium and right ventricle will be dilated and sluggish when the caval tapes are first released. In most cases contractility will improve quickly with modest inotropic support and temporary reduction in circulating volume, in which case the outlook is optimistic. Rhythm can be very important and on many occasions improvement will not occur until sinus rhythm is established. Temporary atrial, ventricular, or atrioventricular sequential pacing can be very helpful, and isoproteronol infusion can be very useful for maintaining an optimal heart rate, aiming to achieve a rate of 100 to 110 beats/minute. Tachyarrhythmias are a more serious problem and greatly limit the usefulness of inotropic agents that have any chronotropic activ- ity. Fortunately, in a short period of time most hearts will recover normal conduction pathways and adapt to moderately elevated pulmonary vascular resistance without the need for elaborate therapeutic exertions.

If patience is not rewarded with gradual improvement, it may herald the full-blown picture of severely elevated pulmonary vascular resistance. Gross findings include a tense pulmonary artery with a dilated right ventricle and right atrium that will typically contract vigorously when empty on total bypass. As attempts are

made to separate from bypass, right-sided pressures are high, cardiac output is low, and systemic pressure is low. The diagnosis is confirmed by measuring left atria1 pressure directly, which will show a large gradient across the lungs. In a case encountered recently, the left atria1 pressure was 5 mm Hg with right atria1 and right ventricular diastolic pressures of 20 mm Hg. Gross observation or an intraoperative echo will con- firm that the left ventricle is empty and contract- ing vigorously.

The syndrome can be seen in an occasional patient in whom resistance problems were not expected, and other explanations must always be considered. Donor factors worth pondering include poor myocardial preservation, right ventricular infarction, and unrecognized trauma (right ventricular contusion, valve injury). Poor preservation is less likely when the left ventricle appears vigorous, and right ventricular infarction in the absence of gross air embolism should be very unusual. Nonetheless, it may not be possible to completely exclude such alternatives and the immediate therapeutic problem is not altered significantly by the diagnosis. The most correct- able possibility is an obstructive gradient across the pulmonary artery anastomosis, evidence for which should be sought by measuring pressures on both sides of the pulmonary artery suture line.

CRAIG R. SMITH

In any event, the full syndrome carries a grave prognosis. Empiric pharmacology will sometimes solve the problem-infusing vasodilators (nitro- prusside, prostaglandin E-l) directly into the pulmonary artery while infusing a selection of potent inotropes and vasoconstrictors (isoproteronol, dopamine, norepinephrine, epinephrine, and amrinone) directly into the left atrium has been successful. Creation of an atria1 septal defect has been suggested, but success has not been reported. The timely application of mechanical assistance probably carries the greatest likeli- hood of salvage in this situation.*

SPECIAL TECHNICAL CONSIDERATIONS

Reoperations. Twenty-one percent of the 257 patients transplanted in the series at Columbia- Presbyterian have had one or more previous open heart procedures, and in one published series (Texas Heart Institute) the figure has been even higher (29.6%).’ In many respects the technical problems presented are similar to those encountered in other reoperations, and it could be argued that the margin for error is increased by the fact that both ventricles will be discarded. The initial objective, safe cannulation for cardiopulmonary bypass through adhesions, is certainly the same. Nonetheless, there are some features of

Fig 14. Implantation, great arteries. The aortic anestomo-

sis is completed with continuous suture beginning with the posterior wall. Note that if neither side is trimmed, the new

aorta will about double in length. (Reprinted with permission.“)

cardiac transplant in this setting that warrant comment.

In general, markedly dilated right ventricles can be difficult to separate from the posterior table of the sternum. If serious difficulty is expected at the outset, femoral-femoral bypass can be instituted before performing the resterno- tomy, which will decompress the right ventricle and give good control of the circulation during dissection through adhesions. This approach carries a penalty in prolongation of cardiopulmonary bypass and the possibility of difficulty with hemostasis, and in the author’s opinion should rarely be necessary.

If ventricular fibrillation is triggered by dissection before enough exposure has been obtained to use internal .paddles, precious moments can be lost arranging delivery of external current. The safety margin can be increased by preoperative placement of selfadhering, low impedance, chlo- ride type external defibrillator pads, which per- mit immediate defibrillation.‘O*ll

If major difficulties develop before the right atrium is safely visualized, venous return can be obtained quickly with a large cannula placed in the expendable right ventricle, converting to bicaval cannulation once right atria1 exposure is obtained. Arterial return can be provided through


the femoral artery, or with a simple stab into any part of the aorta. The aortic cannula can be repositioned later if necessary.

In most cases, careful dissection of adhesions prior to administration of heparin will produce excellent exposure for cannulation of the aorta and right atrium and for placement of tapes around the superior and inferior vena cavae. The more that can be done before heparinization, the easier it becomes to achieve hemostasis after separation from bypass. However, it is usually safest to complete dissection of the ventricles and the pulmonary artery on bypass, especially when the patient has coronary bypass grafts plastered over the pulmonary artery and left ventricle. Adhesions surrounding previous aneurysm re- pairs can be very dense and usually lie against the pericardium in a relationship that puts the left phrenic nerve at risk.

Delineation of the great arteries is perhaps the major challenge in transplant reoperations. Once the patient is on total cardiopulmonary bypass the problem is greatly simplified by entering the right ventricle and feeling the limits of the pulmonary artery from the inside with the fingers of one hand while dissecting on the outside, a manuever reminiscent of hernia surgery.

Patients who have had previous cardiac transplants are easier in some respects, since there is ordinarily excess tissue in both atria and on both great arteries. With relatively little exposure the venous cannulas can be inserted in the native atrium, which is identified by interpolation between the right pulmonary veins and the atria1 suture line, and the aortic cannula can be inserted at a comfortable site in the native aorta. After application of the crossclamp on total bypass, the right atrium of the donor can be entered anywhere convenient and the excision carried around in either direction to the septum, where the left atria1 suture line is easily identified from the inside. The left atria1 suture line is divided from the inside, leaving the ventricles attached by their outflow tracts to the great arteries. The great vessel puzzle is then easily solved by working from the inside out, separating the vessels as much as necessary, and choosing an appropriate level for division with important intravascular landmarks directly in view.

A radical alternative approach has been described by Doty, who suggests performing the

operation through a left thoracotomy when the risk of sternal reentry might be prohibitive.12 Doty describes initial cannulation of the aorta and right ventricle, excision of the ventricles and bicaval transatrial recannulation during a 10 to 15 minute period of circulatory arrest, and a conventional sequence for reimplanation anastomoses, adjusting for the change in surgical orientation.

Atria1 gigantism. The right atrium is very often markedly enlarged in the recipient. The enlargement occurs principally in the medial and superior aspect of the atrium, where the atrium stretches along its attachment to the dilating right ventricle and tricuspid annulus. Extreme right atria1 enlargement is usually quite simple to reduce, by placing the cannulas as far lateral and posterior as possible (close to the interatrial septum) and resecting the right atrium back to within 1 or 2 centimeters of the cannulation sites and inferior caval tape. Further reduction can be achieved by sewing a pleat of the inferior atrium over against the inferior third of the septum, as described later for the left atrium.

Massive left atria1 enlargement is usually seen only in patients who have underlying valvular or congenital heart disease. In such cases most of the redundancy occurs in the dome and in the inferior wall of the atrium, away from the entry of the pulmonary veins and the site of attachment to posterior pericardium. The author prefers to plicate pleats of the dome and inferior wall against the atria1 septum with a simple running suture, taking care not to roll in enough tissue to obstruct the right pulmonary veins. Alternative approaches have been described. Duncan, Peric, and Frazier13 have described a technique that reduces the size of the opening for anastomosis by plicating the midline of the inferior wall, but without producing much reduction in the total volume of the atrium (Fig 15). Although this approach would seem to carry some risk of thrombus formation in the plicated chamber, it was not observed in the case reported by the authors.

Kawazoe et all4 have also described a complex series of intraatrial plications (Fig 16) that could conceivably be applied to giant left atria in transplantation, although the authors had in mind patients undergoing mitral valve procedures.

398 CRAIG R. SMITH

Fig 16. Illustration of the approach dercribed by Duncan et al for reduction of giant atria by plicating each inferior wall. (Reprinted with permission.‘3)

Transposition of the great arteries. Trans- position does not usually present major problems for transplantation. Once the heart is removed, if the great arteries are separated out to their pericardial reflections they fall easily in to a more normal relationship. Any residual discrepancy can usually be corrected by using the excess length left on the donor aorta and pulmonary artery. This approach has been described in a patient who has L-transposition and ventricular inversion (Reitz et al),” in a patient with L- transposition and univentricular heart (Macov- iak et a1),16 and has been applied to three patients with transposition at Columbia-Presbyterian. Even with excess length on the donor vessels it is advisable to complete the pulmonary artery anastomosis before removing the crossclamp, because the anastomosis ends up lying more posterior to the aorta than usual.

A somewhat more complex challenge has been described by Harjula et al,” in a patient who had L-transposition, ventricular inversion with ven-

tricular and atria1 septal defects, a right-sided descending aorta, and a patent ductus, who had had three previous open heart corrections. Pre- sumably because of the right-sided descending aorta, the aortic arch lay posterior and behind the pulmonary artery. Aortic cannulation was not possible, and even with femoral cannulation great difficulty was encountered developing a space for application of the aortic crossclamp. Use of the whole length of the donor ,great arteries allowed satisfactory implantation in a more normal relationship.

Left superior vena cava. For transplantation, the left superior vena cava needs to be ligated. The alternative of leaving the enlarged coronary sinus draining into the new right atrium would require either shifting the left atria1 anastomosis anterior to the coronary sinus into less secure tissue, or excision of a strip of atrioventricular groove containing the coronary sinus for reimplantation into the atrium. Neither option is appealing, and neither option has been reported.


Fig 16. Illustration of the approach described by Kawa-

zoe et al for reduction of giant left atria during operetions on the mitral valve udng rerpiginour intraatrial plications.

(Reprinted with permission.‘?

If an innominate vein and right superior vena cava are present, the left superior vena cava can be ligated with impunity. In the author’s experience this was even possible in a heart-lung transplant when the innominate vein was absent

and the right superior vena cava was smaller than the left. The patient had mild facial and left arm edema that resolved within a few days and was neurologically normal.

Ligation is not an option when the right superior vena cava is absent. This situation was handled successfully by McGiffen and Karp” who used the donor innominate vein and right jugular vein to construct a conduit reaching from the donor superior vena cava to the recipient innominate vein. Venous drainage for cardiopulmonary bypass was achieved by direct cannulation of the inferior vena cava and left superior vena cava, dividing and oversewing the left superior vena cava between the cannulation site and the site of entry into the coronary sinus to allow recipient cardiectomy. The authors correctly point out that other approaches preserving drainage through the coronary sinus, even if possible to perform, would make endomyocardial biopsy through the preferred internal jugular approach virtually impossible because of the sharp turn the bioptome would have to make to get into the right ventricle.

Hypoplastic left heart. Although first performed by Magdi Yacoub in 1984,i9 the technique for transplantation in this complex anom- aly was first described by Bailey et al.” In the donor, removal of the aortic arch and proximal descending aorta is necessary to allow a long spatulating anastomosis in the hypoplastic recipient aorta, and the entire bifurcation of the pulmonary artery should be taken with the donor heart to allow a large anastomosis with the recipient pulmonary artery. In the recipient, initial cannulation for cooling is carried out with a single right atria1 cannula and arterial cannulation of the large ductus, occluding both pulmonary arteries individually with clamps or snares to prevent overcirculation of the lungs. Under profound hypothermia and circulatory arrest the ventricles are removed as usual, and the great vessels are divided by separating the large ligated ductus from the distal aorta, dividing the pulmonary artery flush with its bifurcation and spatulating the underside of the hypoplastic arch out to the ductus insertion. The atria are anastomosed as usual. The pulmonary artery bifurcation of the donor is opened widely and anastomosed to the large pulmonary artery bifurcation in the recipi-

400 CRAIG R. SMITH

PULMONARY TRUNK

LT PULMONARY VV. SUP VENA CAVA

RT. PULMONARY

ent. A long bevel is made in the donor aorta, leaving the inner curvature of the arch intact so that the hypoplastic tongue of recipient tissue containing the arch vessels can be sewn on top to recreate the arch. Arterial cannulation is reestab- lished through the donor innominate trunk, the right atrium is recannulated through the donor appendage, and circulation is resumed with conventional precautions for evacuation of air.

Details of aortic reconstruction will vary de- pending on the extent of recipient aortic hypopla- sia and atresia. Circulatory arrest durations of 45 to 60 minutes can be expected; Bailey’s first case required 73 minutes and had a normal neurologic outcome.

Previous systemic-pulmonary shunts. Blalock-Taussig shunts that have not produced pulmonary stenosis can be ligated in the usual fashion. If necessary for exposure, this can be done after excision of the ventricles, controlling increased left atria1 return with additional cardiotomy suction or reduced bypass flow until the shunt is controlled. Successful use of this approach has been described in passing by Macov- iak et a1.16

Shunts that have produced pulmonary stenosis beyond the pericardial reflection can be ex- tremely difficult to correct and might reasonably

vv.

Fig 17. Heterotopic transplantation, preparation of the donor heart. The right pulmo-

nary veins are oversewn and the Mft pulmonary vein orifbs are connected to form the left

atrial cuff. An incision is mad8 in the superior half of the right atrium, extending posterolater-

ally into the sup8rior vena cava parallel to the interatrial groove. (Reprinted with permission?‘)

’ INF. VENA CAVA

be considered a contraindication to transplant if the uncorrected stenosis would contribute to prohibitive pulmonary vascular resistance. (Trento et al).”

Central shunts (Potts, Waterston) are gener- ally managable even when they have produced significant pulmonary artery stenosis. A Pott’s anastomosis can be controlled most easily by closure from inside the pulmonary artery during a brief circulatory arrest shortly after beginning cardiopulmonary bypass. Control of a Waterston anastomosis is easily achieved by applying the aortic crossclamp distal to the shunt, and the dissection through adhesions necessary to accom- plish this quickly should be carried out before bypass.

Reconstruction is simplified in transplantation by the fact that the aorta can usually be divided distal to (or through) the Waterston anastomosis, and with the ventricles removed and the aorta out of the way, exposure of the pulmonary arteries is greatly improved. Pulmonary stenosis at the site of a Pott’s anastomosis tends to involve the left pulmonary artery quite distally, and exposure may pose prohibitive technical problems. Stenoses in the proximal portions of both pulmonary arteries can be patched extensively with pericardium, prosthetic material, or donor


Fig 18. Heterotopic transplantation, left atrial anastomo- sic. An opening ia made in the

recipient left atrium parallel to the interatrial groove. The anastomosis approximates this

opening to the cuff created in the donor at the site of the left pulmonary veins, which can be enlarged to match. (Reprinted with permission.26)

tissue. Substantial lengths of both donor pulmonary arteries can be splayed open for patching or used end-to-end. With sufficient foresight, additional segments of donor aorta or other pieces of donor vasculature can be harvested for use in more complex reconstructions.

Absent interatrial septum. The surgeon simply makes a judgement about where the septum should lie and sutures the right side of the left atria1 anastomosis to that site along the posterior wall of the common atrium, taking care to avoid obstructing the orifices of the right pulmonary veins. The “septal” (posterior) segment of the right atria1 anastomosis is oversewn to this “septum” as usual. At Columbia-Presbyterian this was performed in one 4-year-old child who had a single ventricle and transposition and had had a complete atria1 septectomy during a previous procedure; 5 years later the experiment was repeated successfully when the child required a retransplant.

Abnormal atrial situs. A right-sided superior vena cava entering a right-sided sinus portion of a “right” atrium satisfies the major technical requirements for transplant-the do- nor heart can be implanted with normal situs, and an internal jugular route for endomyocardial biopsy is present. Cases of situs ambiguous meet- ing this requirement should, therefore, be techni-

cally suitable for transplant, assuming that other abnormalities (such as anomalous pulmonary venous drainage or azygous continuation) can be managed with intraatrial baffles.

Situs inversus is a more imposing problem. The simplest theoretical solution would be to implant the donor heart upside down, connecting the donor aorta to the recipient’s descending aorta and connecting the pulmonary arteries with a graft conduit, but it is doubtful there would be enough space for the ventricles in the superior mediastinum. Other theoretical solu- tions would necessarily involve elaborate reconstructions of venous drainage. Only one case has been reported, in which Doty** reported success with a complex and innovative reconstruction of right-sided systemic venous drainage, using native pericardium in situ to create large portions of the neoatrium.

Heterotopic transplantation. Advocates of heterotopic transplantation have cited the advantage of having the native heart in place during severe rejection episodes, and the advantage of using donors smaller than could be used in the orthotopic position. Published results do not support widespread application of this technique, with l-year survival of 55% and 5-year survival of 22% in one of the few large series reported (49 patients).23 The procedure has been used success-

CRAIG R. SMITH

Fig 19. Hatarotopic transplant, right atrial anastomoda. The anastomosis approximates

the inferior angle of the donor right atriotomy to the midpoint of the posterior edge of the recipient atriotomy, craating 8 diamond anastomosis with a 90”

clockwisa rotation in the donor atrium. (Reprintad with permb- sion.26)

fully in a small number of patients who had pulmonary vascular resistance too high for ortho-

right ventricle and by the donor’s healthy left

topic transplantz4 In one such patient at Colum- ventricle, producing normal cardiac output and

bia-Presbyterian, after 3 years forward output is exercise tolerance from half of the four ventricu-

maintained only by the recipient’s hypertrophied lar chambers. Heterotopic transplant will continue to be useful when the donor heart is too

Fig 20. Harerotopic transplant. graat artarias. The procedure is completed with an and-

to-side anastomosis batwaan the donor aorta and the recipi- ant ascanding aorta. and with a Dacron tube graft conduit connecting the pulmonary arties. (Reprintad with parmission.25)


small for use in the orthotopic position,24 a judgment that might need to be made in the operating room on rare occasions. Desperation use of a small donor for a critically ill patient should be an infrequent occurrence if contempo- rary LVAD/RVAD technology is available.

Disadvantages of the heterotopic procedure include (1) compressive atelectasis of the right lung (infrequent), (2) embolism from thrombi forming in largely bypassed chambers with low flow, especially if a prosthetic valve is present, (3) regurgitant lesions of the atrioventricular valves are a contraindication, and (4) angina or serious arrythmias may persist in the recipient heart.

The details of technique have been well described and illustrated by Frazier et a12’ and by Novitzky et al.26 The donor cardiectomy is modi- fied only by the need to take as much length as possible on the donor superior vena cava, aorta, and pulmonary arteries, and by the need to preserve enough of the left atrium that the right pulmonary vein orifices can be oversewn, which could make transplantation of the donor’s right lung more difficult by limiting left atria1 cuff size. The donor heart is prepared for implantation by

403

closing the right pulmonary veins and inferior vena cava, and by making an incision in the right atrium, parallel and just anterior to the interatrial groove, extending from the midatrium almost to the origin of the azygous vein stump (Fig 17).

Implantation begins with anastomosis between the common orifice of the left pulmonary veins and an incision made in the recipient left atrium just posterior to the interatrial groove anterior to the right pulmonary veins (Fig 18). The right atria1 anastomosis requires careful orientation and is done as a diamond anastomosis to an opening in the middle of the recipient right atrium just anterior to the interatrial septum, with the inferior end of the donor right atriotomy placed at the midpoint of the inferior wall of the recipient atriotomy (Fig 19). The donor aorta is sewn end-to-side to the recipient ascending aorta, and a tube graft of appropriate size is used to connect the pulmonary artery of the donor to the main pulmonary artery of the recipient (Fig 20). A radioopaque marker is placed at the junction of the right atria, as a reference for endomyocardial biopsy.

REFERENCES

1. Carrel A and Guthrie CC: The transplantation of veins and organs. Am Med 10:1101-l 102, 1905

2. Shumway NE: Personal communication, 1989 3. Lower RR and Shumway NE: Studies on orthotopic

homotransplantation of the canine heart. Surg Forum 11:18- 23,1960

4. Debakey ME, Diethrich EB, Glick G, et al: Human cardiac transplantation: Clinical experience. J Thorac Cardio- vast Surg 58:303-3 17, 1969

5. Barnard CN: What we have learned about heart transplants. J Thorac Cardiovasc Surg 56:457-468,1968

6. Stinson EB, Dong E, Schroeder JS, et al: Initial clinical experience with heart transplantation. J Cardiol22:791-803, 1968

7. Hardesty RL, Griffith BP: Multiple cadaveric organ procurement for transplantation with emphasis on the heart. Surg Clin North Am 66:451-457, 1986

8. Farrar DJ. Hill JD, and Gray LA: Heterotopic prosthetic ventricles as a bridge to cardiac transplantation: A multicenter study in 29 patients. N Engl J Med 318:333-340, 1988

9. Lammermeier DE, Nakatani T, Macris MP, et al: Effect of prior cardiac surgery on survival following heart transplantation. Ann Thorac Surg 48:168-172, 1989

10. Wilson RF, Sirna S, White CW, et al: Defibrillation of high-risk patients during coronary arteriography using self- adhesive, preapplied electrode pads. Am J Cardiol 60:380- 382,1987

11. Kerber RE, Martins JB, Kelly KJ, et al: Self-adhesive preapplied electrode pads for defibrillation and cardioversion. J Am Co11 Cardiol3:815-820, 1984

12. Doty DB: Special procedures: Cardiac transplantation, left thoracotomy, in Cardiac Surgery: A Looseleaf Workbook. TRANSPL 21-23,1988

13. Duncan JM, Peric M, Frazier OH: Orthotopic cardiac transplantation in patients with large donor/recipient atria1 size mismatch: Surgical technique. Ann Thorac Surg 44:420- 421,1987

14. Kawazoe K, Shintaro B, Yoshiharu T, et al: Surgical treatment of giant left atrium combined with mitral valve disease. J Thorac Cardiovasc Surg 85:885-892, 1983

15. Reitz BA, Jamieson SW, Gaudiani VA, et al: Method for cardiac transplantation in corrected transposition of the great arteries. J Cardiovasc Surg 23:293-296, 1982

16. Macoviak JA, Baldwin JC, Ginsburg R, et al: Orthoto- pit cardiac transplantation for univentricular heart. Ann Thorac Surg 45:85-86,1988

17. Harjula AL, Heikkila LJ, Nieminen MS, et al: Heart transplantation in repaired transposition of the great arteries. AnnThoracSurg46:611-614, 1988

18. McGiffin DC, Karp RB: Cardiac transplantation in a patient with a persistent left superior vena cava and an absent right superior vena cava. Heart Transplant 3:115-l 16, 1984

19. Yacoub M: Personal communication, 1989 20. Bailey L, Conception W, Shattuck H, et al: Method of

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heart transplantation for treatment of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg 92:1-5,1986

21. Trento A, Griffith BP, Fricker FJ, et al: Lessons learned in the selection of pediatric candidates for heart transplantation. Ann Thorac Surg, 1989, (in press)

22. Doty DB: Cardiac transplantation in atria1 situs inversus. J Thorac Cardiovasc Surg, 1989, (in press)

23. Cooper DKC, Novitzky D, Becerra E, et al: Are there indications for heterotopic heart transplantation in 1986? Thorac Cardiovasc Surgeon 34:300-304.1986

24. Nakatani T, Frazier OH, Lammermeier DE, et al: Heterotopic heart transplantation: A reliable option for a select group of high-risk patients. J Heart Transplant 8:40- 47,1989

25. Frazier OH, Okereke OUJ, Cooley DA, et al: Hetero- topic heart transplantation in three patients at the Texas Heart Institute. Tex Heart Inst J 12:221-232,1985

26. Novitzky D, Cooper DKC, Barnard CN: The surgical technique of heteropic heart transplantation. Ann Thorac Surg 36:476-482,1983

techniques in cardiac transplantation

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