Acute normovolemic hemodilution (ANH). Effects of ANH on leftventricular diastolic function

Ischemia-induced changes of diastolic leftventricular (LV) properties commo nly precede corresponding ECG-changes. In the present experimental study th e consequences of acute normovolemic hemodilution (ANH) induced dilutional anemia (hematocrit, hct 20%) for LV diastolic function were investigated. A total of 22 anaesthetized, splenectomized beagle dogs breathing room air were hemodiluted with isooncotic hydroxyethylstarch solution (6%HAES 200.00 0/0.5) until a hct value of 20% was reached. Before and after ANH intravasc ular blood volume (indocyaningreen dilution technique), global and regional myocardial blood flow (radioactive microspheres technique) and the followi ng parameters reflecting LV diastolic properties were ascertained: 1) the maximum rate of LV pressure decrease (LVdp/dt(min)), 2) slope and intercept of the enddiastolic pressure-volume relationship (ED PVR, conductance technique) 3) the time-constant of isovolumic LV pressure decline "tau". After ANH to hct 20% diastolic LV function was found unchanged. Particularl y the load-independent parameters (EDPVR-slope and tau) remained constant. The decrease of LV dp/dt(min) (2724 +/- 479 vs. -2388 +/- 408 mmHg-sek-1; p <0.05) reflects ANH induced changes of LV pre- and afterload. Signs of sube ndocardial perfusion mismatch were not encountered. Presumed that the coronary vascular system is intact ANH to hct 20% does no t provoque changes of LV diastolic function. Moreover neither myocardial pe rfusion and oxygenation nor myocardial function are endangered by this degr ee of dilutional anemia.