Abstract: Intro Dilated cardiomyopathy is a common cause of heart failure and heart transplant in pediatric patients. The most common etiologies are idiopathic, neuromuscular disorders, myocarditis, familial cardiomyopathies, and inborn errors of metabolism, but reversible causes such as nutritional deficiencies must also be considered. Case A 5 month old male infant presented to the pediatric emergency department after right sided tonic-clonic movements and loss of consciousness at home. Upon arrival, the infant was tachycardic, tachypneic, and dyspneic. Cardiac examination was unremarkable. He was noted to be mildly ill-appearing but neurologically appropriate without focal deficits. Initial laboratory evaluation revealed an ionized calcium=0.67mmol/L and total calcium=4.9mg/dL with otherwise normal electrolytes and renal function. Chest radiograph was notable for cardiomegaly. ECG demonstrated left ventricular hypertrophy and prolonged QTc=511ms. Echocardiogram demonstrated moderately reduced left ventricular function with a shortening fraction of 16% and mild to moderate mitral valve regurgitation. The patient was admitted to the pediatric cardiac intensive care unit where milrinone, calcium gluconate infusions were started. Further investigation revealed low 25-OH vitamin D (4.1ng/mL) as well as significantly elevated alkaline phosphatase (1907 u/L) and elevated PTH (505pg/mL). Repeat echocardiogram after calcium repletion showed improvement in left ventricular size and function, with improved shortening fraction (25%). QTc normalized to 410. The patient was discharged home on enalapril, calcium, calcitriol, and cholecalciferol after 9 days of admission. Discussion This patient presented with seizures and heart failure associated with hypocalcemia. The infant was exclusively breastfed. The differential for hypocalcemia in children of this age may be split into low versus high PTH. Hypocalcemia with low PTH indicates hypoparathyroidism, while high PTH indicates deficient vitamin D intake/absorption or a defect in vitamin D metabolism (renal or hepatic dysfunction). This patient did not demonstrate abnormalities in liver or kidney function, and their vitamin D level was very low, likely indicating deficient Vitamin D. Rickets is the clinical syndrome associated with this deficiency. Nutritional rickets is an uncommon but reversible cause of dilated cardiomyopathy in infants and children. While vitamin D deficiency is common at all ages, the most likely patients to present with cardiac dysfunction are infants less than 1 year of age. Especially at risk are those with darker skin, breastfed infants, and premature infants. Environmental factors such as wintertime and cloud cover may also increase risk. Even in the absence of clinical symptoms of cardiac failure, infants and children with Vitamin D deficiency rickets may demonstrate echocardiographic evidence of depressed left ventricular function as well as ECG changes (abnormal T waves, prolonged QTc), which occur with increasing frequency and severity as the severity of the disease increases. Reassuringly, patients with cardiomyopathy secondary to hypocalcemia respond fully and rapidly to treatment with temporary use of cardiac supportive meds with concurrent repletion of calcium and vitamin D.
