Reproducibility of the measurement of the muscle ergoreflex activity in chronic heart failure.
BACKGROUND
A causative role for symptom generation in heart failure has been attributed to overactive muscle afferents, metaboreflex and mechanoreflex. We examined the reproducibility of the methods commonly used to assess these reflexes.


METHODS
Twelve stable heart failure patients (62.8+/-2.4 years) and 18 normals were studied. The metaboreflex was evaluated on both leg and arm exercises, by performing two runs of 5-min submaximal handgrip and leg exercises. On one run the subjects recovered normally (control recovery), while on the other a post-exercise regional circulatory occlusion (PE-RCO) was induced in the exercising limb, to isolate the stimulation of the metaboreceptor after exercise. The metaboreflex was quantified as the difference in ventilation between the PE-RCO and the control recovery periods with respect to rest. The existence of a mechanoreflex was sought by comparing the ventilatory increment per unit of active work (dV(E)/dVO(2) ratio) between leg passive movement and active low level exercise. The coefficients of variation (CV) were computed to express the reproducibility of these reflexes in heart failure.


RESULTS
The metaboreflex was overactive in patients vs. normals during both arm (7.2+/-2.8 l/min vs. 0.06+/-0.3 l/min) and leg (5.6+/-1.2 l/min vs. 0.5+/-0.2 l/min) tests. The mechanoreflex was not different between patients and normals: dV(E)/dVO(2) during passive movement 48.9+/-18.3 and 22.4+/-26.5; active exercise 42.3+/-18.4 and 31.9+/-18.7 (P=NS). In patients, the CV for the metaboreflex was 23.4% in the arm and 35.3% in the leg, while for the mechanoreflex test CV was 38.1% during passive movement and 21.1% during active exercise.


CONCLUSIONS
The described method of measuring the muscle reflex activity shows an adequate reproducibility in heart failure patients.
Scott
Adam C
AC
National Heart and Lung Institute, and Royal Brompton Hospital, Imperial College School of Science, Technology and Medicine, London, UK.
Francis
Darrel P
DP
Coats
Andrew J S
AJ
Piepoli
Massimo F
MF
D002628:Chemoreceptor Cells / Q000503:physiopathology*; D005080:Exercise Test; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008465:Mechanoreceptors / Q000503:physiopathology*; D040542:Mechanotransduction, Cellular; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010101:Oxygen Consumption; D015203:Reproducibility of Results