[Cardiovascular response to high sustained +Gz stress in dogs].
Objective. To investigate features of electrocardiography (ECG) and arterial pressure in dog during and after +Gz stress. Method. Six anesthetized dogs were catheterized for the measurement of ascending aortic pressure (AP) and common iliac arterial pressure (CIAP). A lead of ECG was monitored continuously. Then, dogs were placed supine in rotatable platform on one arm of an 1.7 m radius centrifuge. The animals were exposed serially to acceleration profiles of up to +7 Gz, consisting of a slow onset to peak acceleration, 90 s peak G, and a rapid decline back to control. A recovery time of at least 20 min was allowed after each acceleration profile. Result. (1) The amplitude of P-wave was influenced by the magnitude of the acceleration (2.3 +/- 0.2 mV at rest vs. 4.5 +/- 0.5 mV at +3 Gz, 4.8 +/- 0.3 mV at +5 Gz and 5.3 +/- 0.7 mV at +7 Gz, respectively P<0.05). (2) It appeared that arterial mean pressure increased and pulse pressure decreased in CIAP during high +Gz stress. (3) AP increased greatly after +Gz stress (17.29 +/- 5.59/11.31 +/- 3.86 kPa at rest vs. 27.53 +/- 6.12/20.62 +/- 1.86 kPa 30s after +7 Gz P<0.01). Conclusion. (1) The change of the amplitude of P-wave reflected the atrial displacement which may be the reason of arrhythmia. (2) The perfusion pressure is an important physiological parameter to the cardiovascular dysfunction during high +Gz stress. (3) Greatly higher AP after +Gz stress could be a feature of vascular exhaustion.
Shi
L J
LJ
Institute of Aviation Medicine, Air Force, Beijing.
Zhang
H J
HJ
Tang
W P
WP
Li
G D
GD
Tan
C
C
Song
L
L
D000054:Acceleration; D000818:Animals; D001011:Aorta; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D004285:Dogs; D004562:Electrocardiography; D006439:Hemodynamics / Q000502:physiology*; D018471:Hypergravity; D007083:Iliac Artery; D011674:Pulse