/snip/
> >When surgeons do a heart transplant they don't reconnect the nerves to the
> >heart. As Nancy Howes explains in her reply, this increases the resting
> >heart rate. This is because there is no sympathetic nerve inhibition of the
> >heart rate. Also, the heart rate responds slowly to exercise, with less
> >increase in heart rate than normal.
/snip/
A minor observation; when the heart is denervated, there is an increased
in the resting heart rate due to the loss of the inhibitory influence of
the para-sympathetic division of the autonomic nervous system. At rest,
with normal innervation, the heart receives both sympathetic and
para-sympathetic input, and the para-sympathetic is dominant. Therefore,
with denervation, the intrinsic rate of depolarization of the sino-atrial
cells is manifest, increasing the heart rate.
Regarding the 6-20 and 0-10 Borg RPE scales; they are both for exertion,
but the 0-10 scales has been adapted for use with patients with pulmonary
disorders by using descriptors for dyspnea. When used for exertion, the
two scales are equivalent. One of the principle reasons for creating the
0-10 scale was that some researchers were criticized for using parametric
statistical procedures on the old RPE scale, because if the scale was
6-20, it couldn't be an interval or ratio scale. So, by converting to a
0-10 scale, the phenomenon was magically converted to a ratio scale.
So, there was no real physiological or clinical reason to convert to the
0-10 scale, and the statistical rationale is false as well, so those who
continue to use the 6-20 scale, keep it up.
Frank Underwood
Evansville, Indiana
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