Neonatal Ventricular Tachyarrhythmias in Medium Chain Acyl-CoA Dehydrogenase Deficiency

Abstract

We describe an unusually severe case of medium chain acyl-CoA dehydrogenase (MCAD) deficiency in a term female neonate, who presented at 12 h of age with lethargy, poor feeding, hypoglycemia and ventricular tachyarrhythmias. While arrhythmias are common in other disorders of fatty acid beta-oxidation, ventricular tachyarrhythmias have rarely been reported with MCAD deficiency in childhood. Since the results of newborn metabolic screening are usually not available within the first 3 days of life, our case highlights the need for health care professionals to be made aware of this early and uncommon but potentially fatal presentation of MCAD deficiency.

Recurrent Ventricular Tachycardia in Medium-Chain Acyl-Coenzyme A Dehydrogenase Deficiency

“…He was resuscitated and ventilated but had further cardiac arrests, associated with ventricular tachycardia and ventricular fibrillation and managed with cardioversion, lidocaine and amiodarone. The final case was particularly similar to our patient (Yusuf et al 2010). She presented with hypoglycaemia and apnoea and was managed with ventilation and intravenous glucose.…”

“…Cardiac arrhythmias are less likely to be directly caused by hypoglycaemia. Indeed, blood glucose concentrations were normal at the time of the arrhythmias in our patient and 2 other reports (Maclean et al 2005;Yusuf et al 2010). It is uncertain which metabolites contribute to the encephalopathy and cause the arrhythmias in these patients: fatty acids, acylcarnitines and acyl-CoA esters may all be responsible.…”

“…Thus, there are a few reports of MCAD deficiency patients who have become encephalopathic without hypoglycaemia (Mayell et al 2007). Our patient and that of Yusuf et al (Yusuf et al 2010) also had seizures at a time that their plasma glucose and ammonia concentrations were normal, several hours after brief periods of hypoglycaemia and hyperammonaemia. Cardiac arrhythmias are less likely to be directly caused by hypoglycaemia.…”

“…A sad and striking feature of our patient's history was that she continued to deteriorate with worsening ventricular tachyarrhythmias despite receiving intravenous glucose for more than 48 h. Two of the other MCAD-deficient babies were also receiving intravenous glucose (at 6.5-7 mg/kg/ min) prior to their ventricular tachyarrhythmias and one had been receiving this for 35 h (Maclean et al 2005;Yusuf et al 2010). Most patients with MCAD deficiency recover from acute decompensation if managed with intravenous glucose; obviously, this corrects hypoglycaemia (if present) and it is generally thought that abnormal metabolites will disappear promptly once the glucose infusion has led to a reduction in the rate of fatty acid oxidation.…”

Prolonged QTc Interval in Association With Medium-Chain Acyl-Coenzyme A Dehydrogenase Deficiency

“…Although various cardiac arrhythmias and cardiomyopathy have been reported in MCAD deficiency, to our knowledge the association of a prolonged QTc interval has not been described. [3][4][5][6][7] QTc interval prolongation may be secondary to congenital or acquired abnormalities and is significant in that it may progress into life-threatening cardiac arrhythmia.…”