Cardiogenic shock and mechanical circulatory support — branching viva

Stage 1 — The compensated presentation

The examiner presents a six-year-old boy three days after a viral illness. He is cold and mottled with weak pulses, a four-second capillary refill, oliguria and a gallop rhythm. His blood pressure is 95/60 (normal for age) and his lactate is 5.2 mmol/L. The echocardiogram shows globally hypokinetic ventricles. [2]

• Why does the normal blood pressure not exclude shock, and what bedside feature confirms the shock is cardiogenic? Children vasoconstrict to preserve blood pressure until late, so the perfusion state defines shock; the gallop and congestion confirm a cardiogenic cause. [13]
• Describe your initial fluid strategy and contrast it with septic shock. Five-to-ten millilitre-per-kilogram aliquots with reassessment for congestion, deliberately less than the ten-to-twenty of septic shock, because the failing ventricle tolerates volume poorly. [12]
• Assign his SCAI stage and state the trigger for escalation. He is stage C (classic hypoperfusion needing inotropes); the trigger for mechanical support is stage E, refractory collapse. [2]

Stage 2 — The refractory deterioration

Six hours later his blood pressure falls to 60/40, the lactate rises to 8 mmol/L, and he remains oliguric on milrinone, dobutamine and adrenaline. The examiner asks for the definitive intervention. [10]

• What has happened, and what is the definitive next step? He is now in refractory cardiogenic shock (stage D to E); deploy venoarterial extracorporeal membrane oxygenation as the first-line rescue, early. [10] [8]
• What is the goal of support in fulminant myocarditis, and what prognosis should you state to the family? Bridge to recovery; fulminant myocarditis often recovers near-normal ventricular function once supported through the storm. [15]
• What complications must you counsel the family about? Bleeding and thromboembolic stroke from mandatory anticoagulation, infection, haemolysis, limb ischaemia and multiorgan failure from delayed deployment. [7] [8]

Stage 3 — The adolescent on durable support

The examiner moves to the outpatient setting. A fourteen-year-old boy with dilated cardiomyopathy is being evaluated for a durable ventricular assist device after a decompensating admission. [13]

• Which durable device suits him, and which device is used for smaller children? A continuous-flow device such as the HeartMate 3 for an adolescent; the Berlin Heart EXCOR paracorporeal pulsatile pump for small children and infants, as trialled by Fraser and colleagues. [3] [5]
• Define the four goals of mechanical circulatory support and state which applies here. Bridge to recovery, bridge to transplant, bridge to candidacy, destination therapy; this boy is a bridge to transplant. [6] [4]
• How would you frame the disposition and follow-up? A paediatric cardiac intensive care unit with mechanical support and transplant capability; the device allows rehabilitation and home discharge during the wait, making adherence and transition to adult care central. [3] [13]