Case report

A 3-month-old female infant of a first cousin marriage was referred to our paediatric ICU with a 4-day history of fatigue, tachypnoea, tachycardia, hypoxia, and respiratory failure. She was born at 38 weeks of gestation, weighing 3580 g. Her mother had not taken any vitamin supplementation during the pregnancy. The patient did not have any vitamin D supplementation and complained about becoming tired when she was sucking during the past 15 days. On admission, she was lethargic (Glasgow Coma Scale: 12) and mildly hypotonic. She had subcostal and intercostal retractions and tachypnoea (68 breaths/minute). Oxygen saturation was 86% on room air and 95% under respiratory support given with a non-rebreathing reservoir mask. She had rales over the lung bases and the liver was palpable 5 cm below the costal margin. Non-invasive ventilation support with high-flow nasal cannula oxygen therapy was started soon after admission. She was tachycardic (182 beats/minute), hypotensive (68/34 mmHg), and her capillary refill time was 4 seconds. Electrocardiography revealed sinus tachycardia with a heart rate of 140/dk, left ventricle hypertrophy, and a P-R interval duration of 0.8 seconds (Fig 1). Chest radiography revealed an enlarged cardiac silhouette, with a cardiothoracic index of 0.64. Laboratory findings showed metabolic acidosis with high levels of lactate (5.2 mmol/L). Complete blood count, procalcitonin, and C-reactive protein levels were within normal ranges. Serum calcium was 7.9 mg/dL, albumin was 4.1 mg/dL, ionised calcium was 0.6 mmol/L (normal: 1.2–1.38 mmol/L), phosphorus was 2.9 mg/dL (normal: 4.5–6.7 mg/dL), alkaline phosphatase was 597 U/L (normal: 150–420 U/L), parathyroid hormone was 214 pg/mL (normal: 15–65 pg/mL), 25-hydroxy vitamin D was 3 ng/mL (normal: 17–54 ng/mL), troponin I was 0.375 ng/mL (normal: 0–0.16 ng/mL), and creatine kinase-MB was 39.8 U/L (0–25 U/L). Echocardiography revealed left ventricular enlargement and systolic dysfunction with left ventricular ejection fraction of 25%. In addition, the wall of both ventricles was thickened. The patient was diagnosed with nutritional hypocalcaemic rickets-related dilated cardiomyopathy and further investigations were planned for probable concomitant metabolic disorders. Medications for heart failure like adrenaline, milrinone, levosimendan, and furosemide were given at different times when required. In addition to these therapies, aspirin (4 mg/kg), vitamin D (intramuscular 75,000 IU), and intravenous calcium (50 mg/kg elemental calcium) treatments were started. On the fourth day, respiratory distress worsened, she was intubated, and invasive mechanical ventilation support was initiated. On the seventh day, a second dose of vitamin D (intramuscular 75,000 IU) was administered and intravenous calcium therapy was changed to enteral calcium lactate (75 mg/kg). Three days after administration of second vitamin D dose, echocardiography revealed elevated left ventricle systolic functions compared with initial echocardiography before Vitamin D supplementation and severe hypertrophy of both ventricles with diastolic dysfunction (Fig 2). On the 15th day of admission, lysosomal enzyme activity of the acid alpha-glucosidase was very low at 0.2 µmol/L/hour – normal >3.3 µmol/L/hour – confirming infantile-onset Pompe disease. With low enzyme activity, hypotonia, hepatomegaly, and hypertrophic cardiomyopathy, the patient was diagnosed with infantile-onset Pompe disease. Afterwards, homozygous c.896T >C (p.Leu299Pro) missense mutation was detected. The formal report procedure was initiated for obtaining the recombinant human acid alpha-glucosidase enzyme from abroad but the patient died because of sepsis and cardiorespiratory failure on the 25th day of admission.

Figure 1

Electrocardiography view of the patient.

Figure 2

Two-dimensional echocardiographic view of the patient revealing severe left ventricular hypertrophy.