Persistent hyperinsulinemic hypoglycemia with left ventricular hypertrophy and dysrhythmia: a case report

Recurrent Hypoglycemia Secondary to Insulinoma in an Adult With Beckwith-Wiedemann Syndrome

Beckwith-Wiedemann syndrome (BWS) is a rare genetic disorder characterized by genetic and epigenetic changes on the chromosome 11p15.5 region, which includes genes that are important for fetal and postnatal growth. Children with BWS have a higher chance of having hypoglycemia, hyperinsulinemia, and malignancies early in life, although hypoglycemia caused by an insulinoma that develops later in life has not been reported. We describe the diagnosis of insulinoma in a 53-year-old man with BWS in this case report. This is the first case report of insulinoma in an adult with this syndrome.

Current Status of Childhood Hyperinsulinemic Hypoglycemia in Turkey

Congenital hyperinsulinism (CHI) is a rare disease characterized by dysregulated insulin secretion from pancreatic β-cells. Recurrent hypoglycemia can lead to neurological insult and permanent brain injury. Recently, there are important advances in understanding the genetic mechanisms, histological characteristics, imaging, and surgical techniques of congenital hyperinsulinemic hypoglycemia that could reflect to improvement in the clinical care of infants with this disorder. In Turkey, there is a high rate of consanguinity, thus, the incidence of CHI is expected to be high. Until now, there are no nationwide data regarding the disorder, and some individual case reports or case series had been published. Determining the characteristics of Turkish patients with CHI can help develop a different perspective on this rare disease. In this review, we evaluated the clinical and molecular characteristics of Turkish patients with CHI based on reports published in the literature. The most frequently seen mutations were ABCC8 gene mutations (n=37), followed by HADH (n=11) and KCNJ11 gene (n=7) mutations. A total of 141 Turkish patients with CHI were reported until now. Among them, 115 patients had been genetically analyzed, and 56 of them had one of the mutation leading to hyperinsulinism.

Insulinoma presenting with cardiac arrest and cardiomyopathy

A 33-year-old woman presented with ventricular fibrillation cardiac arrest and was found to have a blood glucose of 1.83 mmol/L. Cardiac catheterisation revealed a dilated left ventricle with an ejection fraction (EF) of 26% and angiographically normal coronary arteries. Continuous dextrose infusion was required to treat hypoglycaemia, which prompted consideration of insulinoma as a possible cause for her cardiomyopathy. Whipple's triad was demonstrated; a 72 h fast provided biochemical evidence of insulinoma, and imaging localised a tumour in her pancreas. The tumour was resected and pathology confirmed insulinoma; pancreaticoduodenectomy cured her hypoglycaemia. No alternate cause of cardiomyopathy was found and 4 months after surgery her EF improved to 41%. High insulin levels can close cardiac K(ATP) channels associated with dilated cardiomyopathy; the catecholamine surge from hypoglycaemia may also contribute to ventricular remodelling. Hypoglycaemia can cause QT segment prolongation, and may have precipitated fibrillation in this patient's arrhythmia-prone myocardium.

The association of cardiac ventricular hypertrophy with congenital hyperinsulinism

OBJECTIVE

Ventricular hypertrophy (VH) has been observed in children with congenital hyperinsulinism (CHI), a condition of hypoglycaemia characterised by dysregulated insulin secretion, but the prevalence is not known.

PATIENTS AND METHODS

Cardiac assessment was performed in children (n=49) with CHI at diagnosis and follow-up. Two dimensional and Doppler echocardiography studies were used to assess cardiac structures, while M-mode study was used to measure left ventricular (LV) dimensions, subsequently converted to Z scores. Where possible, LV hypertrophy was confirmed by LV mass index (g/m(2.7)) >95th centile.

RESULTS

Cardiac structural lesions were found in 14 (28%) children. At initial echocardiography, VH was present in 31 (65%) children with median (range) LV posterior wall dimension in diastole Z scores of +1.6 (-2.4 to +5.8) and interventricular septal wall dimension in end diastole Z scores of +1.9 (-1.7 to +17.2). At follow-up echocardiography, performed after an interval of 178 (45-390) days, VH persisted in 16 (33%) children. In regression analysis, the presence of VH (odds ratio (95% confidence intervals) 1.1 (1.0-1.2), P=0.04) at initial echocardiography was correlated with maximum glucose requirement at diagnosis, indicating that severity of CHI at presentation may play a role in the pathogenesis of VH.

CONCLUSIONS

A significant proportion of children with CHI have cardiac structural lesions. A majority also have VH, which may be associated with the severity of CHI at diagnosis. VH may persist in some children, which requires careful long-term cardiac review.