Heart or Lung plus Kidney - Professor Richard Kirk 2023

The ISHLT pediatric registry in 2018 reported (1990 and 2017) only 32 combined heart-kidney and 1 lung-kidney transplants. The corresponding adult figures are 1527 and 48. However, combined renal transplants are uncommon but increasing with 6% of adult Htx now undertaken in combination with a kidney.

Renal impairment is common in end stage cardiac failure, especially in older Fontan patients.  End stage renal disease requiring renal replacement therapy (dialysis or transplant) also occurs in 10% of transplant recipients 15 years post transplant due to adverse effects of immunosuppression. Simultaneous or sequential renal transplantation is therefore often a consideration at the time primary or retransplantation is proposed.

Some patients are already established on dialysis and the decision making is relatively clear cut. For those with less severe renal impairment creatinine clearance is crucial in deciding management. Creatinine clearance is usually measured using eGFR methods but these may underestimate the degree of renal impairment due to loss of muscle mass. Cystatin C estimation is therefore preferable. The significance of albumin in the urine, particularly in Fontan patients is uncertain. Kobashigawa presents an algorithm for assessing adults with either acute or chronic renal impairment for combined transplantation which is very useful. Data in pediatrics demonstrates that post transplant outcomes are significantly better when renal transplantation is combined with heart (or heart-lung and lung) transplantation if the patient is already established on dialysis or has a GFR < 35ml/min/1.73m2. Adult data is similar but suggests a GFR < 45 ml/min/1.73m2.

The data clearly suggests that combined transplants (simultaneous) have better post transplant outcomes compared to sequential transplantation. However there are considerable barriers to combined transplants.The threshold for transplanting across HLA antibodies varies between solid organ programs within institutions. Renal programs are usually more reluctant to cross HLA antibodies with the effect that whilst the cardiac team will accept the heart, the renal team might reject the kidney. Hemodynamic instability might also compromise renal function so some programs delay the kidney transplant until they are sure cardiac output is sufficient and otherwise place the organ with a "back-up" recipient.

Post transplant protocols may differ between the teams. Cardiac transplants require fluid restriction to prevent rght ventricular failure but (at least traditionally) renal transplants require a fluid load at implant for better outcomes. Compromises are necessary! Fortunately immunosuppression guidelines (Kovak et al 2020) are usually similar for both organs but must be agreed beforehand.

Finally outcomes for Heart-Kidney outcomes are not as favorable if a marginal heart donor is used (Shin et al)