P2.119: Cardiogenic shock in a pediatric patient with hemoglobin SC disease

Introduction: Cardiovascular complications in sickle cell disease often include pulmonary hypertension or left ventricular diastolic dysfunction secondary to the impact of sustained hemolytic anemia and recurrent vaso-occlusive episodes. Myocardial infarction and microvascular ischemic injury are very rarely described and poorly understood clinical entities, particularly in childhood sickle cell disease.

Case Description: A 9-year-old female with hemoglobin SC disease without prior cardiac history nor significant sickle cell complications was found unresponsive by her family, prompting intubation for airway protection shortly after arrival to her local emergency department. She was febrile, tachycardic but normotensive, and initial laboratory values were notable for a lactate of 16 mmol/L and hemoglobin of 1.85 g/dL. Her reticulocyte count was low, she had splenomegaly and thrombocytopenia, and her haptoglobin was low with an elevated lactate dehydrogenase. One unit of packed red blood cells (RBCs) was transfused over one hour, then a second unit was transfused over 3-4 hours. With greater than expected elevation in her hemoglobin to 8.1 g/dL by arrival to our pediatric intensive care unit (PICU), there was concern for autotransfusion from sequestered RBCs.
Shortly after arrival to the PICU, she became acutely hypotensive with initial echocardiographic findings of severely decreased left and moderately decreased right ventricular function. There was normal biventricular size without segmental wall motion abnormalities. Electrocardiogram demonstrated a low atrial rhythm with intermittent junctional escape beats, and high sensitivity troponin I levels peaked at 1,329.1 ng/L. She stabilized with volume resuscitation and vasoactive support with epinephrine and milrinone. Following extubation on hospital day 4, repeat echocardiogram demonstrated complete normalization of her biventricular function. She was found to have parvovirus B19, a contributory factor to her severe anemia, although no unifying diagnosis was definitively made to explain her acute cardiogenic shock.

Discussion: We theorize that our patient experienced cardiogenic shock secondary to transient microvascular myocardial ischemia after autotransfusion of sequestered RBCs. This is based on her grossly abnormal cardiac enzyme levels and the time course of her severe myocardial dysfunction. Myocardial infarction in sickle cell disease is a rarely described phenomenon, even in the adult literature. In most cases, patients are younger adults without conventional cardiovascular risk factors, as the pathophysiologic mechanism is thought to be related to microvascular dysfunction secondary to impaired circulation of sickled cells, shear injury with resultant endothelial damage, and a procoagulant state in the setting of systemic vasculopathy.

Conclusion: This is the one of the first cases to describe cardiogenic shock and suspected microvascular myocardial ischemic injury in a pediatric patient with hemoglobin SC disease. As the true incidence of coronary microvascular disease in childhood sickle cell disease remains unknown, there should be wider awareness and investigation into this clinical entity.