The Journal of Thoracic and Cardiovascular Surgery, Vol 72, 618-625, Copyright © 1976 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Effect of thoracotomy upon the carotid sinus control of regional hemodynamics in the dog
RJ Bagshaw and RH Cox
The effects of bilateral thoracotomy upon the operating characteristics of
the carotid sinus reflex were examined in 11 vagotomized dogs.
Pressure-flow relationships in the aorta, celiac, mesenteric, renal, and
femoral arteries were studied as a function of pressure in the isolated
carotid sinuses. These relationships were analyzed to give the carotid
sinus reflex operating point values and sensitivities of pressure, flow,
impedance, and power for each regional vascular bed. Following thoracotomy
there was a significant fall in the closed-loop operating point pressure
(CLOP) ( p less than 0.005). The operating point values and sensitivities
for each regional flow and resistance together with the corresponding mean
and oscillatory kinetic and pressure power were not significantly altered
by thoracotomy. Renal characteristic impedance at the operating point
significantly increased following thoracotomy (p less than 0.05), as did
the aortic characteristic impedance for carotid sinus pressures (CSP) above
the closed-loop operating point. The operating sensitivity of renal
characteristic impedance was decreased (p less than 0.05). Possible
mechanisms underlying these changes are discussed.