Heart Transplantation Technique

Updated: Feb 26, 2016
  • Author: Donald M Botta, Jr, MD; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Technique

Approach Considerations

The applicability of cardiac transplantation is limited by the availability of suitable donors. All potential donors have succumbed to brain death secondary to some catastrophic event. The underlying pathology of the donor, including cardiac contusion, cocaine use, cardiac pathology, or social history, often precludes donation. Because of the short preservation time tolerated by the heart (4-6 hours), procurement distances are limited.

Potential heart donors must meet brain death criteria and be free of cardiac pathology. Echocardiographic examination remains the best initial screening mechanism for potential donors. A normal ejection fraction (>50%) with normal valvular structure and function and an absence of left ventricular hypertrophy (as determined by echocardiography) are indicators of an excellent heart for transplantation.

Minimal abnormalities on echocardiography (eg, trivial tricuspid or mitral regurgitation, marginal left ventricular hypertrophy, or reduced ejection fraction) may also be indicators of an acceptable organ, depending on the history of the donor and the condition of the recipient. In instances where the recipient is in extremis, a less-than-ideal donor heart may be accepted in order to save the patient’s life. Donors who have a significant smoking history must be screened for coronary artery disease (CAD) with cardiac catheterization.

Current donor criteria include age younger than 65 years (though the association between heart transplant survival and donor age may not be a strictly linear one [25] ), normal cardiac function, and absence of CAD. Once these criteria are met, donor and potential recipients are matched according to blood group (ABO) compatibility and size.

The final decision regarding the suitability of the donor heart can be made only on the basis of direct inspection by an experienced surgeon. A median sternotomy incision is performed to allow inspection of the heart. Care is taken to assess the organ for potential contusions and overall function. The heart is flushed with cold cardioplegia solution, removed, and placed into cold sterile electrolyte solution for transport.

The recipient operation is performed by using cardiopulmonary bypass. The recipient heart is removed, and the donor heart is inserted in its place. The left atrial anastomosis is performed, followed by the right atrium and the great vessels.

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Transplantation of Heart

While preparing a graft for transplantation, the authors look for a patent foramen ovale. If a patent foramen is present, it is closed. Many centers now perform tricuspid valve annuloplasty on donor grafts as prophylaxis against development of tricuspid regurgitation in the postoperative period. [26] The incidence of tricuspid regurgitation after heart transplantation is reported to be as high as 47-98%. [27]

During the cardiac transplantation procedure, the ventricles are excised, leaving the great vessels, right atrium, and left atrium of the recipient (see the first image below). The donor heart is then sewn to these areas (see the second and third images below).

View of the recipient's chest after the heart is r View of the recipient's chest after the heart is removed, with the patient on cardiopulmonary bypass.
Suturing of the donor heart. Note that the left at Suturing of the donor heart. Note that the left atrial anastomosis is performed first.
Completed operation. Note suture lines on now-impl Completed operation. Note suture lines on now-implanted heart.

A cardiac allograft can be sewn in either a heterotopic or an orthotopic position. The authors rarely perform heterotopic heart transplants because of the inherent problems (eg, pulmonary compression of the recipient, difficulty obtaining endomyocardial biopsy, need for anticoagulation); however, heterotopic transplantation (see the image below) is an excellent technique for patients with severe pulmonary hypertension.

Heterotopic transplantation. Heterotopic transplantation.

Orthotopic heart transplantation is performed either with the classic Shumway-Lower technique or as a bicaval anastomosis (see the images below). Currently, there is a trend toward reverting to bicaval anastomoses rather than right atrial anastomoses in an attempt to decrease the incidence of postoperative tricuspid insufficiency.

View after cardiectomy, showing cuffs for bicaval View after cardiectomy, showing cuffs for bicaval anastomosis.
Completed bicaval transplantation technique. Completed bicaval transplantation technique.

The Shumway-Lower method is simpler and saves perhaps 10-15 minutes of ischemic time. One advantage of the bicaval method is that, by avoiding a large right atrium, the surgeon can maintain better atrial transport. Another claimed advantage of this technique is a lower reported incidence of tricuspid regurgitation.

An additional advantage of the bicaval technique is that when the ischemic time of the allograft is too long because of transportation or surgical extraction of the recipient heart/ventricular assist device, the donor heart can be better preserved by continuous cold retrograde blood cardioplegia through the coronary sinus. Of course, topical cooling of the graft continues to be the primary means of graft preservation.

After the procedure, the patient is maintained on a combination of pressor agents while the donor heart regains energy stores. The patient’s ionized calcium level is carefully monitored and replaced with calcium chloride because the function of the denervated heart initially is extremely dependent on circulating calcium ions. The acid-base status of the patient is also carefully monitored and corrected.

Immunosuppression is started soon after surgery. Several regimens can be used, including pretransplantation induction therapy and simple postoperative maintenance therapy; the choice of regimen depends on the training and experience of the transplant center. [10, 11]

Once stabilized, the patient is rapidly weaned from the ventilator and the pressors. The posttransplant hospital stay can be as short as 5 days, depending on the condition of the recipient before the operation.

In the transplantation process, the sinoatrial nodes of the donor and recipient remain intact, and both are present within the recipient. For approximately 3 weeks after surgery, electrocardiography (ECG) demonstrates 2 P waves; however, the heart rate and electrical activity of the new heart are purely dependent on the intrinsic electrical system of the heart, not on the neurologic input from the recipient.

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Complications

Complications after transplantation include bleeding from the suture lines. This is a rare occurrence but may require reexploration in the early postoperative period.

Hyperacute rejection can occur immediately after blood flow is restored to the allograft and up to 1 week after the procedure, despite therapeutic immunosuppression. Bridging with mechanical assistance may be advantageous in acute allograft rejection. [28]

Infection is the primary concern in transplant patients. Preventive measures should be instituted. During the early posttransplant course, bacterial infections are of primary concern. Fungal infections can appear if the patient is diabetic or excessively immunosuppressed. Prophylaxis for Pneumocystis jiroveci is universally administered, as is therapy for cytomegalovirus (CMV) infection. Maintain vigilance for other uncommon infectious processes, including Listeria, Legionella, Chlamydia, and Nocardia infection. [29]

Psychiatric disturbances from steroid therapy can occur in the immediate posttransplant period. These disturbances may be predicted from the pretransplant psychiatric evaluation and thus averted.

Cardiac rejection is to be expected and should be detected by endomyocardial biopsy. [30, 31, 32] Depending on the severity of the incident, the process can be treated with steroid therapy alone, polyclonal antibody therapy, or monoclonal antibody therapy.

Allograft vascular disease is the main cause of late graft failure and death. A progressive concentric myointimal hyperplasia develops in the coronary arteries, sometimes as early as 3 months after transplantation. The cause of the process is unclear. However, CMV infection and recurrent rejection episodes are thought to be associated with the cause. Research suggests that the initial ischemia-reperfusion injury, coupled with repeated rejection episodes, might contribute to the process.

The only therapy available for allograft vascular disease is retransplantation. The process can sometimes be treated by stenting the diseased vessels. Drug-eluting stents appear to be more effective in treating cardiac allograft vasculopathy than bare-metal stents are. Drug-eluting stents reduce target lesion revascularization, as well as rates of cardiac death and nonfatal myocardial infarction. [33]

In pediatric patients, there is a 30% increase in the risk of graft loss within 6 months when the ischemic time is longer than 3.5 hours. [34]

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