Ventricular repolarization changes during thyrotropin releasing hormone test

Changes in Serum Electrolytes, ECG, and Baroreflex Sensitivity during Combined Pituitary Stimulation Test

The mechanisms by which hypoglycemia increases cardiovascular mortality remain unclear. The aim of the study is to investigate changes in serum electrolytes, norepinephrine concentrations, electrocardiography, and baroreflex sensitivity (BRS) and associations between corrected QT (QTc) intervals and the changes in serum electrolytes during combined pituitary stimulation test (CPST). We recruited the subjects who were admitted to the Gyeongsang National University Hospital to undergo CPST between September 2013 and December 2014. Participants were 12 patients suspected of having hypopituitarism. Among 12 patients, cardiac arrhythmia in two patients occurred during hypoglycemia. There were significant differences in serum levels of potassium (P < 0.001), sodium (P = 0.003), chloride (P = 0.002), and calcium (P = 0.017) at baseline, hypoglycemia, and 30 and 120 minutes after hypoglycemia. Also, there was a significant increase in heart rate (P = 0.004), corrected QT (QTc) interval (P = 0.008), QRS duration (P = 0.021), and BRS (P = 0.005) at hypoglycemia, compared to other time points during CPST. There was a positive association between QTc intervals and serum sodium levels (P < 0.001) in 10 patients who did not develop arrhythmia during CPST. This study showed that there were significant changes in serum levels of potassium, sodium, chloride, and calcium, as well as heart rate, QTc interval, QRSd, and BRS during CPST. It was revealed that QTc intervals had a significant association with concentrations of sodium.

Takotsubo Cardiomyopathy in a Patient With Presumptive Autoimmune Polyendocrine Syndrome II

Takotsubo cardiomyopathy (TCM) is an increasingly described form of transient cardiomyopathy in which patients develop a distinct left ventricular apical ballooning typically following a significant emotional or physical stress. The etiology of this syndrome is not clear, but it is likely that direct catecholamine toxicity to the susceptible myocardium plays a role. The syndrome is most common in women and has been described in association with a variety of forms of physiologic or emotional stress. In general, the prognosis is favorable and complete recovery is common. The authors report the case of a young woman with presumed autoimmune polyendocrine syndrome II (APS II) who developed TCM after presenting with adrenal insufficiency. APS II is an endocrine disorder in which Addison’s disease can occur with autoimmune thyroid disease, type 1 diabetes mellitus, premature ovarian failure, vitamin B12 deficiency, vitiligo, and other manifestations. Hormonal preconditioning and psychological stress may trigger TCM.