Cardiac transplantation and ventricular assist devices — formative SAQs

SAQ 1 — The infant with a refractory dilated cardiomyopathy (20 marks, ~15 minutes)

A four-month-old infant with a known idiopathic dilated cardiomyopathy and an ejection fraction of 18 percent is on a loop diuretic, an ACE inhibitor and caloric supplementation. Over two weeks the tachypnoea worsens, feeds take longer with sweating, the weight crosses two centiles downward, and the creatinine begins to rise. The advanced heart-failure team is consulted. [4]

Questions

1. Define what is happening to this infant and why it triggers escalation beyond medical therapy. (4 marks) [6]
2. Outline the device options for an infant of this size and state which durable device is most likely to be used, with the evidence that supports it. (5 marks) [1]
3. Explain the strategic goal of the device in this child and what must be excluded before the child is listed for transplantation. (5 marks) [4]
4. State the leading complications of the device you have chosen and the surveillance they require. (6 marks) [10]

Model answer (must-hit)

1. The infant has refractory advanced heart failure — the persistent progression of signs (tachypnoea, sweaty feeds, failure to thrive) and the emergence of end-organ dysfunction (rising creatinine) despite maximal guideline medical therapy. This is the trigger to escalate beyond pharmacotherapy to an advanced heart-failure centre for assessment, because the whole pathway is a race to support and transplant the child before irreversible end-organ and pulmonary vascular injury. The neurohormonal vicious cycle can no longer be interrupted medically, so mechanical support and transplantation enter the plan. [6]
2. For an infant of this size the durable device is the paracorporeal pulsatile Berlin Heart EXCOR, which has pump sizes small enough for neonates and infants and whose bridge-to-transplant role was established by the Almond 2013 cohort of US children. Short-term support such as VA-ECMO or a CentriMag would be reserved for acute collapse, and a miniaturised continuous-flow implantable device is generally not an option for the smallest patients. Device choice is governed above all by the size of the child. [1]
3. The strategic goal is a bridge to transplantation — the device unloads the ventricle, restores nutrition and growth, and supports the child through the wait for a donor organ. A bridge-to-recovery strategy would be reserved for myocarditis or a recoverable cardiomyopathy. Before listing, the team must exclude a reversible cause — in particular a tachycardia-induced cardiomyopathy from an uncontrolled supraventricular tachycardia, which resolves with rate or rhythm control — and must measure the pulmonary vascular resistance by catheterisation, because a fixed high resistance predicts donor right-heart failure and, above a threshold, contraindicates orthotopic transplantation. [4]
4. Stroke is the dominant complication of the Berlin Heart EXCOR and a leading cause of death on support, so any new neurological sign needs urgent imaging and a neurology and haematology review. Infection of the driveline, pump pocket or bloodstream is the other major morbidity, alongside bleeding from anticoagulation, haemolysis and pump thrombosis. Surveillance therefore combines mandatory anticoagulation monitoring (titrated to an institutional target), serial neurological examination, driveline-site care and infection surveillance, and serial echocardiography to confirm adequate ventricular unloading. [10]