Cardiogenic shock and mechanical circulatory support — formative SAQs

SAQ 1 — Fulminant myocarditis in a school-age child (10 marks, 15 minutes)

A previously well six-year-old boy presents three days after a febrile respiratory illness. He is cold and mottled with weak pulses, a capillary refill of four seconds, oliguria and a gallop rhythm. His blood pressure is 95/60 mmHg (normal for age), his respiratory rate is 42, and his lactate is 5.2 mmol/L. The electrocardiogram shows widespread ST and T-wave changes. The echocardiogram shows a globally hypokinetic left ventricle with a moderate pericardial effusion but no tamponade physiology. A diagnosis of cardiogenic shock from fulminant myocarditis is made. ^[2]

a) Explain why the normal blood pressure does not exclude shock, and state the bedside feature that confirms the shock is cardiogenic rather than distributive. (2 marks) ^{[2] [13]}

b) Outline your initial resuscitation, naming the fluid strategy and contrasting it with septic shock, the inotrope agents you would use, and the immediate disposition. (4 marks) ^{[12] [11]}

c) Using the SCAI classification, assign this child's stage on arrival and state the feature that marks progression to the stage requiring mechanical circulatory support. (2 marks) ^[2]

d) 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. What has happened, what is the definitive next intervention, and what is the expected goal and prognosis of that intervention in fulminant myocarditis? (2 marks) ^{[10] [15]}