Heart rate response to Valsalva manoeuvre. Reproducibility in normals, and relation to variation in resting heart rate in diabetics.

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Abstract
The reproducibility of the heart rate response to the Valsalva maneuver was assessed in 12 young normal subjects who each repeated the maneuver 10 times. The length of the RR intervals before, during and after each Valsalva maneuver was measured from an ECG and the changes expressed as 2 ratios: the tachycardia and the Valsalva ratio. The within-subject variation was .+-. 0.044 for the tachycardia ratio and .+-. 0.18 for the Valsalva ratio, the between-subject variation was 0.10 for the tachycardia ratio and 0.37 for the Valsalva ratio. The heart rate response to the Valsalva maneuver was reproducible in 7 older normal subjects. In 100 diabetic subjects with varying degrees of autonomic neuropathy, the heart rate response to the Valsalva maneuver was compared with the heart rate variation from a resting ECG. The heart rate variation correlated sinificantly with both the tachycardia ratio (r = 0.727, P < 0.001) and the Valsalva ratio (r = 0.659, P < 0.01). The heart rate response to the Valsalva maneuver is reproducible in normal subjects and in diabetics, heart rate variation can simply be used as a test of autonomic function when more sophisticated tests are not available.