Beat-to-beat variation of heart rate in diabetic patients with autonomic neuropathy and in completely cardiac denervated patients following orthotopic heart transplantation.
Dysfunction of the vagal nerve, an early symptom in the development of autonomic neuropathy, can be assessed reliably by the beat-to-beat variation in heart rate. Patients after a cardiac transplantation are a unique model to investigate the beat-to-beat variation of a completely denervated heart. Heart rate and the beat-to-beat variation during normal and deep respiration were investigated in diabetic subjects with an autonomic neuropathy (n = 10), age and sex matched healthy controls (n = 10) and cardiac transplanted patients (n = 10). Further studies during pharmacological blockade of the parasympathetic nervous system with atropine were performed. In the denervated heart the coefficient of variation of the beat-to-beat interval was 0.38 +/- 0.02% during normal respiration, compared to 1.32 +/- 0.13% (P less than 0.0001) and 2.56 +/- 0.13% (P less than 0.0001) in the diabetic and control subjects, respectively. Administration of atropine (2 mg intravenously) decreased the coefficient of variation of the RR-interval to 0.73 +/- 0.09% in the diabetic patients (P less than 0.0005) and to 0.67 +/- 0.07% in the controls (P less than 0.0001), whereas the coefficient of variation remained unaffected in the cardiac denervated patients (0.39 +/- 0.02%). In the three groups an almost parallel increase of the RR-variation was observed during deep respiration at a rate of 6 breaths/min (from 0.38 +/- 0.02% to 1.99 +/- 0.38% in cardiac transplanted patients, P less than 0.0025; from 1.32 +/- 0.13% to 3.10 +/- 0.43% in diabetic patients, P less than 0.0025; from 2.56 +/- 0.13% to 5.42 +/- 0.94% in healthy controls, P less than 0.005). We conclude that a beat-to-beat variation of heart rate is present in the completely denervated heart. This RR-variation can not be influenced by a pharmacological blockade of the parasympathetic nervous system with atropine. The beat-to-beat variation increases during deep respiration not only in healthy controls but also in diabetic patients with autonomic neuropathy (partially denervated hearts) and cardiac transplanted patients (completely denervated hearts). This indicates an intracardiac mechanism in the modulation of heart rate.
Center of Internal Medicine, University Hospital, Johann Wolfgang Goethe University, Frankfurt am Main, F.R.G.
S
S
Zeuzem
H G
HG
Olbrich
C
C
Seeger
G
G
Kober
K
K
Schöffling
W F
WF
Caspary
D001285:Atropine; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D003389:Cranial Nerve Diseases / Q000503:physiopathology; D003929:Diabetic Neuropathies / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D016027:Heart Transplantation / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000187:drug effects; D012119:Respiration / Q000502:physiology; D013562:Sympathectomy; D014630:Vagus Nerve / Q000503:physiopathology*
D001285:Atropine