Effect of packed cell volume on diastolic coronary artery pressure-flow relations in the dog

Publisher Website
Google Scholar
Abstract
To elucidate the role of the haemorheological properties of the perfusate in the coronary circulation, the diastolic pressure-flow relation was studied in nine open chest heart blocked dogs with minimal vasomotor tone when blood with various packed cell volumes (12-67%) was used as perfusate. An electrical analogue model with proximal resistance R1, capacitance C, distal resistance R2, and the zero flow pressure intercept Pint was derived from the observation of the pressure-flow relation to support the data analysis. The diastolic pressure decay was then determined after the perfusion line had been clamped to calculate stop flow coronary artery pressure (Psf). The stop flow coronary artery pressure decreased in relation to packed cell volume (r=0.45, p1+R2, which reflects the inverse of the steady state pressure-flow slope, decreased simultaneously with the packed cell volume (r=0.62, p2/(R1+R2) by our model prediction decreased in relation to packed cell volume (r=0.5, p1+R2 for the highest packed cell volume (50–69%) were 17.8(1.1) mmHg, 25.1(1.3) mmHg, and 0.48(0.05) mmHg·ml−1min·l00 g−1 respectively, whereas those for the lowest packed cell volume (10–29%) were 13.4(0.8) mmHg, 19.7(1.0) mmHg, and 0.24(0.02) mmHg·ml−1·min·100 g−1. The pressure difference between the stop flow coronary artery pressure and the zero flow pressure intercept may be due to the non-linearity in the pressure-flow relation at a low perfusion pressure. The left ventricular end diastolic pressure and great cardiac vein pressure did not change in relation to the packed cell volume of the coronary perfusate. Thus it is concluded that packed cell volume is one factor determining the high zero flow pressure.