Ischemic change on electrocardiogram induced by hypoglycemia in a diabetic patient

Hyperinsulinism in a child presenting with cardiac ischemia and bradycardia

A 5-year-old boy referred to our service with suspected sinus node dysfunction. In addition to the arrhythmia, he had moderate mitral valve regurgitation and depressed ventricular function during a hypoglycemic episode. Cardiac abnormalities resolved with glucose infusion. We believe that hypoglycemia was responsible for the cardiac manifestations and it should be considered in unexplained rhythm disturbances or ischemia.

Electrocardiographic alterations during hyperinsulinemic hypoglycemia in healthy subjects

BACKGROUND

We evaluated the arrhythmogenic potential of hypoglycemia by studying electrocardiographic (ECG) changes in response to hyperinsulinemic hypoglycemia and associated sympathoadrenal counterregulatory responses in healthy subjects.

METHODS

The study population consisted of 18 subjects, aged 30-40 years. Five-minute ECG recordings and blood samplings were performed at baseline and during the euglycemic and hypoglycemic hyperinsulinemic clamp studies. PR, QT, and QTc intervals of electrocardiogram and ECG morphology were assessed from signal-averaged ECG.

RESULTS

Although cardiac beat interval remained unchanged, PR interval decreased (P < 0.01) and QTc interval (P < 0.001) increased in response to hyperinsulinemic hypoglycemia. Concomitant morphological alterations consisted of slight increases in R-wave amplitude and area (P < 0.01 for both), significant decreases in T-wave amplitude and area (P < 0.001 for both), and moderate ST depression (P < 0.001). Counterregulatory norepinephrine response correlated with amplification of the R wave (r =-0.620, P < 0.05) and epinephrine response correlated with flattening of the T wave (r =-0.508, P < 0.05).

CONCLUSIONS

Hyperinsulinemic hypoglycemia with consequent sympathetic humoral activation is associated with several ECG alterations in atrioventricular conduction, ventricular depolarization, and ventricular repolarization. Such alterations in cardiac electrical function may be of importance in provoking severe arrhythmias and "dead-in-bed" syndrome in diabetic patients with unrecognized hypoglycemic episodes.