In those with progressive heart failure and surgically uncorrectable congenital heart disease, such as atresia or diffuse hypoplasia of the pulmonary arteries, dual heart-lung transplantation may also be indicated.

Heart-lung transplantation may be a viable option in patients with either end-stage heart disease with concomitant lung disease, or more commonly, end-stage lung disease with concomitant heart disease too severe for single organ transplantation. There are no specific guidelines for conditions in which cardiac transplantation alone versus dual heart-lung transplant should be performed. From a cardiologist’s perspective, the severity of the heart disease is first considered with respect to the possibility of cardiac transplant, and the decision to perform dual transplantation is based on consultation with pulmonologists, taking into account the severity of lung disease and prognosis with the existing lungs. However, the reverse scenario is more common, with cardiac disease secondary to primary lung disease; for example, severe right ventricular dysfunction due to pulmonary hypertension in a patient with parenchymal lung disease. The cardiac and pulmonary diseases may also be unrelated, such as case of emphysema and ischemic cardiomyopathy in a smoker.

Patients being considered for dual heart-lung transplant with pulmonary hypertension typically suffer from idiopathic pulmonary hypertension, secondary pulmonary hypertension or pulmonary hypertension following a previous attempt at repair for a congenital heart defect.

For cases of Eisenmenger’s syndrome and congenital heart disease, especially those with multiple anatomical abnormalities, dual heart-lung transplantation is the commonly preferred choice, based on analyses of UNOS data demonstrating superior outcomes after heart-lung vs bilateral or single lung transplant in this cohort [8] and subsequent confirmatory studies [9, 10]. However, in cases where the congenital abnormality is amenable to surgical repair, isolated lung transplant has been demonstrated to achieve similar survival and complication outcomes to dual heart-lung transplant [11].

For pulmonary hypertension, the choice of whether to deploy dual-heart lung transplant or bilateral lung transplantation only, varies by center; a review of practice patterns across 35 centers worldwide demonstrates that North American centers tend to prefer double-lung transplants over dual heart-lung transplant, whereas the converse is true in Europe [12]; possible explanations have included the relative scarcity of donor hearts in North America. Furthermore, available evidence suggests that for primary or secondary hypertension without other severe complications, bilateral lung transplantation is non-inferior to dual heart-lung transplantation in terms of survival [13, 14]. However, a more controversial area remains regarding the choice of procedure for patients with severe right ventricular dysfunction in addition to pulmonary hypertension. While studies are limited, a recent multicenter analysis from the SRTR database demonstrated that of patients hospitalized prior to transplantation due to right heart failure, there was a statistically significant survival benefit of dual heart-lung transplant over bilateral lung transplant. Further supporting the notion that heart-lung transplant may be more beneficial in this cohort is a 217-patient study demonstrating superior freedom from BOS-related death and no difference in long-term survival in the dual organ transplant group compared with bilateral lung transplant [15]. Thus, in for patients with severe right ventricular dysfunction in addition to pulmonary hypertension, dual heart-lung transplant is generally preferred to bilateral lung transplantation alone. At some centers, isolated heart transplant is considered for congenital heart disease patients with evidence of reasonable right heart function, i.e. if pulmonary vascular resistance is 5 Wood units or less and/or the transpulmonary pressure gradient is less than 12 mmHg [16, 17].

The general guidelines for listing for dual heart-lung transplantation are very similar to those for cardiac transplantation alone, as addressed in Chap. 3; factors such as a recipient age older than 60, multiple comorbidities, previous thoracic surgery, are considered unfavorably with regard to listing, although correlation with poorer outcome has not been definitively established in the dual-transplant population. Patients with disease processes requiring dual heart-lung transplantation often have a somewhat unpredictable clinical course, and in combination with a combined donor shortage, can result in long waits. Partially because of this, a significant proportion of patients listed are high risk due to progressive decline of cardiac and pulmonary function.

With regard to formal evaluation for transplant, the process is very similar to that of cardiac transplantation alone, as addressed in Chap. 3; transplantation is generally considered when patients have marked functional limitations in activities of daily living, combined with poor exercise tolerance as measured by cardiopulmonary exercise testing. General guidelines recommend transplantation based upon a predicted life expectancy of 2 years or less despite optimal medical therapy and in the absence of contraindications [3], although the exact timing is controversial.

For those with congenital heart disease and Eisenmenger’s syndrome, additional clinical features that should prompt consideration for listing for dual heart/lung transplantation include worsening cyanosis, worsening of right ventricular function and worsening pulmonary hypertension unresponsive to treatment, and decreasing oxygen saturation (below 60% on exercise). These should be evaluated in conjunction with hemodynamics, each patient’s unique cardiac anatomy and the overall health and functionality of the patient. Many congenital heart disease patients present with their own unique complications and pathophysiology and do not fit neatly into standard model of single-organ failure on which current recommendations are based. Additional risks are present, such as in those with a failing Fontan circulation who are sicker due to protein-losing enteropathy and progressive hepatic and renal dysfunction. Furthermore, the number of possible donors may be limited due to pre-formed antibodies secondary to frequent prior blood transfusions. Many of these patients have undergone previous surgeries and present technical challenges due to adhesions, altered anatomy, and the presence of vascular collaterals [9–11,16,17]. Deteriorating quality of life due to progressive decline in cardiopulmonary function and increased hospital readmissions can be markers for referral and listing [9, 10, 16] (Fig. 16.2).

For those with combined cardiac and pulmonary disease, additional factors such as consistently low oxygen saturation, increasing frequency of exacerbations, a forced expiratory volume of below 30% of predicted are known to be associated with poor survival [18], and thus should merit consideration for listing for dual heart-lung transplant.

A thorough pre-operative assessment can guide listing and aid in achieving optimal management. In addition to the usual pre-operative assessments mentioned in Chap. 3, detailed imaging with computed tomography should be performed to assess for aorto-pulmonary collaterals in congenital heart disease patients, which have been demonstrated to result in increased bleeding and would need to be controlled early during cardiopulmonary bypass [10]. Patients with primary lung disease will require additional assessment of their lung function, including pulmonary function tests and CT of the chest.

As with cardiac transplantation, patients should be constantly monitored and reassessed as to whether they remain eligible for dual heart-lung transplant; a failure to delist when patients deteriorate while on the waiting list may result in worse outcomes [3]. Patients who deteriorate rapidly often require extracorporeal support, an accepted strategy as bridge-to-transplantation in both individual cardiac and lung transplantation fields. However, the role of ECMO as bridge-to-transplant in dual-organ candidates is less clear, with current data demonstrating higher mortality [3, 19].

With regard to procurement of the donor heart/lung block, a median sternotomy incision is made for initial inspection of the heart/lung block. The block is then mobilized, taking care to achieve minimal handling of the pulmonary tissue. Management of the cardiac donor is addressed in Chap. 7, and similar protocols are applied to the heart-lung donor; the heart is flushed with cold cardioplegia solution, and the lungs are simultaneously flushed with cold modified UW/Collins solution after prostaglandins are administered into the pulmonary artery. The heart-lung block is then removed and placed into a sterile cold electrolyte solution for transport; the trachea should be occluded during storage and transport. While ex-vivo perfusion technologies have emerged as successful methods of reducing ischemic time for both heart and lung preservation alone, dual organ ex-vivo perfusion development remains at the pre-clinical stage [22].

The recipient operative procedure is performed by initiating cardiopulmonary bypass. The heart and lungs are removed, with care taken to preserve the phrenic nerves and to address the bronchial artery circulation so as to prevent postoperative bleeding complications; the donor heart and lungs are inserted. The tracheal anastomosis is then performed, followed by the right atrial anastomosis and the aortic anastomosis. Due to the limited vascularity of the area, care is taken to keep the donor trachea as short as possible [23]. Effective and careful hemostasis is a highly important factor in successful heart/lung transplantation, given the increased risk of post-operative bleeding in this cohort [3].

Overall, the post-operative management guidelines outlined in Chap. 9 still hold true for dual heart-lung transplants, and as detailed in Chaps. 10 and 11, the immunosuppression and infection protocols used in heart transplant are also applicable to patients undergoing heart-lung transplantation. However, some additional specific factors regarding lung management must also be considered. From the cardiologist perspective, many of these aspects will be addressed by the pulmonology team, but it is prudent to be aware of potential complications.

For heart-lung transplants, the approach to mitigating and managing complications is similar to that for isolated heart transplant patients, detailed in Chaps. 9, 10 and 11. However, cardiologists should also be aware of the potential lung-specific complications in this cohort, as most complications following dual heart-lung transplant are lung-related.

Chronic lung allograft dysfunction (CLAD) is detected clinically by a decline in lung function: commonly approximated by measuring the forced expiratory volume in 1 s (FEV₁). The histopathologic findings for CLAD are distinct from the aforementioned a-grade or b-grade ACR. Historically, chronic rejection of the lung allograft has been synonymous with the term bronchiolitis obliterans syndrome (BOS) which refers to lesions found in the terminal (non-cartilaginous) airways. Because these lesions were often associated with lymphocytic infiltrates, it was thought that BOS was equivalent to chronic rejection. It is now known that other factors, independent of the immune response against the lung allograft, contribute to the pathogenesis of BOS. In addition, other pathological processes that lead to chronic rejection have been identified. In addition to BOS, other patterns of rejection with distinct histological findings have been described. These include restrictive allograft syndrome (RAS), characterized by a decline in FEV₁ of more than 20% and a decline in total lung capacity (TLC) of more than 10% (Fig. 16.4).