Cardiac systolic function recovery after hemorrhage determines survivability during shock.
BACKGROUND
Small animal model has not been available to study cardiac pathophysiology during hemorrhagic shock. The main purpose of this study, therefore, was to establish earlier differences in left ventricle functional disturbances during hypovolemia comparable in survival and nonsurvival animals. Ventricular pressure-volume relationships have become well established as the most rigorous and comprehensive venue to assess intact heart function.


METHODS
Studies were performed in anesthetized hamsters subjected to a 40% of blood volume hemorrhage to induce the hypovolemic shock. A miniaturized conductance catheter was used to measure left ventricular pressure and volume. Derived from the pressure-volume measurements, cardiac performance was evaluated using systolic and diastolic function indices.


RESULTS
Thirteen animals were included; all animals survived the hemorrhage. Survival rate after 30 minutes of hypovolemic shock was 61.5%. End-systolic pressure was improved at the late stage of shock in the survival group, whereas no change of this index was found in the nonsurvival group. No significant differences in end-diastolic pressure and relaxation time constant were found between the nonsurvival and the survival groups. Fifteen minutes after the hemorrhage, the stroke work per stroke volume ratio significantly improved in the survival compared with nonsurvival, which also restored blood pressure.


CONCLUSIONS
The unique advantage of the pressure-volume methodology over all other available approaches to measure cardiac function is that it enables more specific measurement of the left ventricle performance independently from loading conditions and heart rate. Our findings demonstrated that failure to recover cardiac systolic function after hemorrhage, is a major determinant of mortality during hypovolemic shock.
Chatpun
Surapong
S
Department of Bioengineering, University of California, San Diego, La Jolla, California 92093-0412, USA.
Cabrales
Pedro
P
D000818:Animals; D002306:Cardiac Volume; D006224:Cricetinae; D004195:Disease Models, Animal; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D011379:Prognosis; D020127:Recovery of Function / Q000502:physiology*; D012771:Shock, Hemorrhagic / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D013318:Stroke Volume; D015996:Survival Rate; D013599:Systole; D016277:Ventricular Function, Left / Q000502:physiology*
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