Thoracic organ transplantation
Dr Christiaan Barnard performed the first human heart transplant in Cape Town, South Africa, in 1967. The operation was based on the experimental work of Richard Lower and Norman Shumway in Stanford, and Shumway subsequently went on to pioneer successful cardiac transplantation in the clinic. Heart transplantation is now considered an effective treatment for selected patients with end-stage cardiac failure. The most common indications for heart transplantation are idiopathic cardiomyopathy and ischaemic heart disease, but other indications include valvular heart disease, myocarditis and congenital heart disease.
Transplantation is considered only in patients with end-stage heart disease which has failed to respond to all other conventional therapy and where predicted survival without transplantation is only 6—12 months. Suitable candidates are New York Heart Association (NYHA) class III (symptoms on mild exertion) or class IV (unable to perform any physical activity without discomfort, which may occur at rest). Transplantation is usually limited to patients under the age of 65 years who do not have irreversible damage to other organ systems. The preoperative assessment is rigorous and measurement of pulmonary vascular resistance is mandatory because when it is raised the perioperative mortality is high.
Technique of heart transplantation
A median sternotomy is performed and the patient is given systemic heparin, placed on cardiopulmonary bypass and cooled to 280C. After cross-clamping the aorta, the recipient heart is excised at the mid-atrial level. The donor heart is then removed from ice and the left atrium is then opened by making incisions in the posterior wall between the orifices of the pulmonary veins to create an atrial cuff. The left and then right atrial anastomoses are performed and the aortic and pulmonary arterial anastomoses are then completed . The patient is then re-warmed and weaned from cardiopulmonary bypass. Total orthotopic cardiac transplantation is an alternative but rarely used procedure in which the entire recipient heart is excised and the donor heart is implanted by caval (superior and inferior), pulmonary vein (right and left), aorta and pulmonary arterial anastomosis. Occasionally, heterotopic cardiac transplantation is undertaken where the donor heart is placed adjacent to and augments the recipient’s own heart.
Heart—lung, single-lung and double-lung transplantation
Pulmonary transplantation became a clinical reality when Dr Bruce Reitz performed the first successful combined heart—lung transplant in 1981. Combined heart—lung transplantation is still sometimes used, especially for patients with pulmonary vascular disease where there is cardiac dysfunction due to congenital (e.g. Eisenmenger’s syndrome) or acquired cardiac dysfunction. For most patients with end-stage pulmonary disease, however, single- or double-lung transplantation has now replaced heart—lung transplantation. Lung transplantation is more economical in terms of organ usage, although if heart—lung transplantation is undertaken for isolated respiratory disease, the healthy native heart can be used for transplantation — the so-called ‘domino procedure’. Heart—lung transplantation is performed through a median sternotomy taking particular care to avoid injury of the phrenic and vagus and recurrent laryngeal nerves during excision of the recipient heart and lungs. The recipient right atrium and aorta are divided as for orthotopic cardiac transplantation and the donor heart—lung block is readied for implantation, incising the right atrium from the divided inferior vena cava. An end-to-end tracheal anastomosis is performed, and the right atrial and aortic anastomoses are performed as for cardiac transplantation.
Single- and double-lung transplantation is an effective therapy for selected patients with end-stage chronic lung disease where declining lung function limits life expectancy. Suitable candidates typically have NYI-IA class III or IV symptoms and a life expectancy of less than 2 years despite optimal medical therapy. Common indications are pulmonary fibrosis, pulmonary hypertension and cystic fibrosis. Single-lung transplantation is performed for pulmonary fibrosis. Patients with cystic fibrosis and other forms of septic lung disease require excision of both native lungs and bilateral or en bloc double-lung transplantation, because single-lung transplantation results in soiling of the transplant from the native diseased lung. Single-lung transplantation is performed through a posterolateral thoracotomy, and double-lung transplantation through bilateral thoracotomy or median sternotomy. During lung transplantation the donor pulmonary veins on a left atrial cuff are anastomosed to the recipient left atrium. Next, the bronchial anastomosis and the pulmonary arterial anastomosis are completed. Cardiopulmonary bypass is usually required if pulmonary hypertension is present. Dehiscence of the airway anastomosis used to be common after heart—lung and lung transplantation but improvements in organ preservation and surgical technique have dramatically reduced the incidence of this often fatal complication to < 5 per cent. Late airway stenosis at the bronchial anastomosis due to ischaemia occurs in around 10 per cent of bronchial anastomoses and is treated by dilatation.
Outcome after thoracic organ transplantation
One- and 5-year graft survival after heart transplantation is around 85 and 70 per cent, respectively. The results after heart—lung and lung transplantation are less good with 1-year graft survival rates of around 75 per cent and 5-year survival rates of around 40 percent.
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