Is Impaired Baroreflex Sensitivity a Predictor or Cause of Sudden Death in Insulin-dependent Diabetes Mellitus?
✍ Scribed by Lawrence, I.G.; Weston, P.J.; Bennett, M.A.; McNally, P.G.; Burden, A.C.; Thurston, H.
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 120 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0742-3071
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✦ Synopsis
Sudden death at night is known to occur in young patients with insulin-dependent (Type 1) diabetes mellitus (IDDM) but the aetiology is uncertain. A cardiac arrhythmia has been postulated, but there has been little evidence to support this. We present the case of a 31-year-old man with IDDM of 17 years duration, who died suddenly while asleep. Over preceding months, he had had strict glycaemic control (HbA 1 8.9 %), normal 24 h blood pressure (mean 131 ± ± ± 2.1/76 ± ± ± 2.2 mmHg), no evidence of microangiopathy or endothelial dysfunction and normal standard clinical tests of autonomic function. An electrocardiogram was similarly unremarkable, with a QT c interval of 0.414 s, and an echocardiogram had demonstrated normal left ventricular mass index (96.4 g m -2 ). However, there was no nocturnal dip in heart rate (daytime 74 ± ± ± 2.7, and nocturnal 68 ± 1.6 beats min -1 ), and he had grossly impaired baroreflex sensitivity during Phase 4 of the Valsalva manoeuvre (0.5 ms mmHg -1 ), with power spectral analysis studies suggesting an abnormality of parasympathetic function. The coroner's autopsy demonstrated no structural abnormalities. We hypothesize that abnormal baroreflex sensitivity could either predict a risk of or account for some of the unexplained deaths in IDDM, in that relative overactivity of the sympathetic nervous system could cause ventricular arrhythmias.