Cardiac repolarization during hypoglycaemia and hypoxaemia in healthy males: impact of renin-angiotensin system activity.
OBJECTIVE
Activity in the renin-angiotensin system (RAS) may influence the susceptibility to cardiac arrhythmia. To study the effect of basal RAS activity on cardiac repolarization during myocardial stress induced by hypoglycaemia or hypoxaemia in healthy humans.


RESULTS
Ten subjects with high RAS activity and 10 subjects with low RAS activity were studied on three different occasions: (i) hypoglycaemia (nadir P-glucose 2.7 +/- 0.5 mmol/L), (ii) hypoxaemia (nadir pO(2) 5.8 +/- 0.5 kPa), and (iii) normoglycaemic normoxia (control day). QT parameters were registered by Holter monitoring. Hypoglycaemia and hypoxaemia induced QTc prolongation (P < 0.001, both stimuli). The QT/RR slope and the VR increased as a function of hypoglycaemia, but were unaffected by hypoxaemia. Low RAS activity was associated with a steeper QT/RR slope in the recovery phase after both stimuli: hypoglycaemia: P = 0.04; hypoxia: P = 0.03. RAS activity had no impact on QTc [P = 0.48 (hypoglycaemia) and P = 0.40 (hypoxaemia)] or any of the other outcome variables.


CONCLUSIONS
Basal RAS activity has significant impact on QT dynamics, but not the corrected QT interval, during recovery from hypoglycaemia and hypoxaemia. The impact, however, is modest and more subtle than initially expected. The clinical relevance is unclear.
Due-Andersen
Rikke
R
Endocrinology Section, Division of Internal Medicine I, Nordsjaellands Hospital - Hillerød, Helsevej 2, Hillerød DK-3400, Denmark. rsa@noh.regionh.dk
Høi-Hansen
Thomas
T
Olsen
Niels Vidiendal
NV
Larroude
Charlotte Ellen
CE
Kanters
Jørgen Kim
JK
Boomsma
Frans
F
Pedersen-Bjergaard
Ulrik
U
Thorsteinsson
Birger
B
D000328:Adult; D018592:Cross-Over Studies; D015716:Electrocardiography, Ambulatory; D006801:Humans; D007003:Hypoglycemia / Q000150:complications* / Q000503:physiopathology*; D000860:Hypoxia / Q000150:complications* / Q000503:physiopathology*; D007328:Insulin; D061389:Insulin, Regular, Pork; D008133:Long QT Syndrome / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D010102:Oxygen Inhalation Therapy; D012084:Renin-Angiotensin System / Q000502:physiology*; D012307:Risk Factors; D016037:Single-Blind Method
D007328:Insulin; D061389:Insulin, Regular, Pork; C000006:insulin, neutral