Heart-Lung Transplantation Health Article

Definition

Heart-lung transplantation is the replacement of the native diseased heart and lungs by transplant of donor heart and lungs.

Purpose

Heart-lung transplantation is required when blood ventilation (air exchange) is inhibited. Inhibited oxygen and carbon dioxide transfer prevents the delivery of oxygen to the tissue and results in carbon dioxide levels in the blood that are higher than normal. Additionally, pulmonary hypertension can cause compromised cardiac function.

Demographics

There are factors which absolutely contraindicate (rule out) heart-lung transplantation, including multiple organ system dysfunction, current substance abuse, bone marrow failure, active malignancy, and HIV infection. Other relative contraindications include age greater than 55, anorexia, obesity, peripheral and coronary vascular disease, ventilator support, steroid dependency, chest wall deformity, and resistant infections by bacterial and fungal agents. Mental health status should be addressed, as well.

Patients who are limited in daily activity, as defined by their doctors, and have a limited life expectancy, are candidates for heart-lung transplantation. These patients suffer from untreatable end-stage pulmonary, organ, and/or vascular disease. Most often, the diagnosis includes primary pulmonary hypertension brought on by congenital blood vessel defects that include malformations in the lung. Congenital cardiac defects and other diseases may also be responsible.

Donor matching is managed by the Organ Procurement and Transplantation Network (OPTN), in which all organ centers must participate according to Federal Medicare and Medicaid programs. Established criteria for donor organ matching include the following: anatomic and immunologic compatibility between the donor and recipient; medical urgency; efficiency in organ distribution for improved organ viability; and ethical considerations. After a match for anatomic and blood group compatibility with the patients on the donor list, the organs are distributed on the basis of seniority in list standing among suitable recipients. Patients with IPF are provided special consideration on organ donor waiting lists. The average waiting time on the heart-lung transplant list is 795 days.

Description

Cardiac monitoring is a necessary part of heart-lung transplantation. Under general cardiac anesthesia, an incision is made in the patient's chest to access the heart and lungs. Anticoagulation (anti-clotting) medications are provided, and cardiopulmonary bypass to a heart-lung machine is instituted. Blood flow is discontinued through the heart by application of a clamp across the aorta. The surgeon removes the diseased organs: in the heart, the native right and left atriums are left intact, along with the native aorta beyond the coronary arteries. This provides large suture lines that allow decreased surgical time and result in fewer bleeding complications.

The donor heart is dissected to match the remaining native heart and aorta. The sutures are made to join the structures. Once completed, the cardiac chambers are deaired as the organs fill with the patient's blood that is diverted away from the heart and lung machine. Mechanical ventilation of the donor lungs helps to purge any remaining air from the cardiac and pulmonary structures and inflate the lung tissue.

Diagnosis/Preparation

History, examination, and laboratory studies are performed prior to referral to a transplant center. These records are reviewed on-site for qualification to be placed on the United Network for Organ Sharing (UNOS) national waiting list. Procedures necessary for evaluation include a chest x ray, arterial blood samples, spirometric and respiratory flow studies, ventilation and perfusion scanning, and cardiac catheterization of both the right and left heart.

Aftercare

The patient will be treated in the intensive care unit upon completion of the surgery, and cardiac monitoring will be continued. Medications for cardiac support will be continued until cardiac function stabilizes. Mechanical circulatory support may be continued until cardiac and respiratory functions improves. Ventilator support will be continued until the patient is able to breathe independently. Medications to prevent organ rejection will be continued indefinitely, as will medications to prevent infection. The patient will be evaluated before discharge and provided with specific instructions to recognize infection and organ rejection. The patient will be given directions to contact the physician after discharge, along with criteria for emergency room care.

Risks

General anesthesia and cardiopulmonary bypass carry certain risks unassociated with the heart-lung transplant procedure. Graft rejection and technical failure are a result of lung injury sustained during the stoppage and restarting of the organ. Infection by cytomegalovirus (CMV) occurs in the first year, but is usually treatable. Immunosuppressive drugs to prevent rejection have side effects associated with malignancies; lymphomas or tumors of the skin and lips being most common. Osteoporosis and nephrotoxicity are also associated with the immunosuppressive therapies.