Hypoglycaemia and electrocardiographic changes in a subject with diabetes mellitus

Changes in cardiac repolarisation during spontaneous nocturnal hypoglycaemia in subjects with type 1 diabetes: a preliminary report

AIMS

Experimental studies have revealed that hypoglycaemia can result in morphological changes in electrocardiographic repolarisation in subjects with type 1 diabetes. However, the influence of spontaneous nocturnal hypoglycaemia on repolarisation morphology in a 'real life' situation is not clear.

METHODS

Adults with type 1 diabetes (n = 11) underwent continuous glucose monitoring with a subcutaneous sensor and digital 12-lead ECG recording for three nights. T-wave morphology was analysed with custom-made software during both hypoglycaemia (glucose <3.5 mmol/l at least 20 min) from ten consecutive heart beats in the middle of the deepest hypoglycaemia and from a control nonhypoglycaemic period (glucose ≥5.0 mmol/l) from the same recording.

RESULTS

In the comparison of 10 hypoglycaemia-control pairs, heart rate (65 ± 12 beats/min during normoglycaemia versus 85 ± 19 beats/min during hypoglycaemia, p = 0.028) increased and the QT_c interval (439 ± 5 vs. 373 ± 5 ms, respectively, p = 0.025) decreased significantly during hypoglycaemia. The spatial QRS-T angle (TCRT) was reduced, and the roughness of the T-wave loop (T-E) increased significantly (p = 0.037 for both) in the patients during hypoglycaemia.

CONCLUSIONS

In adults with type 1 diabetes, spontaneous nocturnal hypoglycaemia results in morphological changes and increased heterogeneity of global cardiac repolarisation. These changes may contribute to the risk of 'dead in bed' syndrome encountered in young individuals with type 1 diabetes.

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.

Corrected QT Interval Prolongation during Severe Hypoglycemia without Hypokalemia in Patients with Type 2 Diabetes

BACKGROUND

To evaluate the effects of severe hypoglycemia without hypokalemia on the electrocardiogram in patients with type 2 diabetes in real-life conditions.

METHODS

Electrocardiograms of adult type 2 diabetic patients during the episodes of severe hypoglycemia and the recovered stage were obtained and analysed between October 1, 2011 and May 31, 2012. Patients who maintained the normal serum sodium and potassium levels during the episodes of severe hypoglycemia were only selected as the subjects of this study. Severe hypoglycemia was defined, in this study, as the condition requiring active medical assistance such as administering carbohydrate when serum glucose level was less than 60 mg/dL.

RESULTS

Nine type 2 diabetes patients (seven men, two women) were included in the study. The mean subject age was 73.2±7.7 years. The mean hemoglobin A1c level was 6.07%±1.19%. The median duration of diabetes was 10 years (range, 3.5 to 30 years). Corrected QT (QTc) intervals were significantly increased during the episodes of severe hypoglycemia compared to the recovered stage (447.6±18.2 ms vs. 417.2±30.6 ms; P<0.05). However, the morphology and the amplitude of the T waves were not changed and ST-segment elevation and/or depression were not found during the episodes of severe hypoglycemia.

CONCLUSION

In this study, QTc interval prolongation during the episodes of severe hypoglycemia was observed without hypokalemia. Therefore, the distinct alterations in cardiac repolarization during the episodes of severe hypoglycemia may not be associated with hypokalemia.

Ampulla cardiomyopathy after hypoglycemia in three young female patients with anorexia nervosa

Ampulla cardiomyopathy is named after the echocardiographic abnormalities occurring in this condition, characterized by extensive akinesis (ballooning ) of the apical region with hypercontraction of the basal segment of the ventricle. We describe 3 young female anorexia nervosa patients showing evidence of this cardiac complication after hypoglycemia. One case was complicated by echocardiographically confirmed ampulla cardiomyopathy while the other 2 patients showed increases in myocardial enzymes and transient electrocardiographic abnormalities consistent with this complication. The precipitating event for all three patients was hypoglycemic coma, and this is the first case report in which this factor lead to the complication of ampulla cardiomyopathy in anorexia nervosa patients.