Vasodilatation with angiographic contrast medium resulted in a steeper diastolic pressure-flow velocity slope (0.80 vs 0.35 cm/s/mmHg, p<0.001) and a lower zero flow pressure intercept (p<0.05).
Does vasodilatation with angiographic contrast medium alter the diastolic coronary artery pressure-flow velocity relationship in conscious humans?
In conscious humans, the coronary diastolic pressure-flow velocity relationship is linear and consistent with a vascular waterfall model, where flow is regulated by changes in both zero flow pressure and coronary resistance.
p-value: p=<0.001
We characterised the diastolic pressure-flow velocity relationship in the normal left coronary artery of conscious man before and after vasodilatation with angiographic contrast medium. Phasic coronary artery pressure and flow velocity were measured in ten patients during individual diastoles (0.5 to 1.0 s) using a 20 MHz catheter-tipped, pulsed Doppler transducer. All pressure-flow velocity curves were linear over the diastolic pressure range of 110 +/- 15 (SD) mmHg to 71 +/- 7 mmHg (r = 0.97 +/- 0.01). In the basal state, values for slope and extrapolated zero flow pressure intercept averaged 0.35 +/- 0.12 cm X s-1 X mmHg-1 and 51.7 +/- 8.6 mmHg, respectively. Vasodilatation resulted in a 2.5 +/- 0.5 fold increase in mean flow velocity. The diastolic pressure-flow velocity relationship obtained during peak vasodilatation compared to that during basal conditions was characterised by a steeper slope (0.80 +/- 0.48 cm X s-1 X mmHg-1, p less than 0.001) and lower extrapolated zero flow pressure intercept (37.9 +/- 9.8 mmHg, p less than 0.05). Mean right atrial pressure for the group averaged 4.4 +/- 1.7 mmHg, while left ventricular end-diastolic pressure averaged 8.7 +/- 2.8 mmHg. These observations in man are similar to data reported in the canine coronary circulation which are consistent with a vascular waterfall model of diastolic flow regulation. In this model, coronary blood flow may be regulated by changes in diastolic zero flow pressure as well as in coronary resistance.
Dole et al. (Sat,) conducted a other in Normal left coronary artery (n=10). Vasodilatation with angiographic contrast medium vs. Basal state was evaluated on Diastolic pressure-flow velocity relationship slope and zero flow pressure intercept (p=<0.001). Vasodilatation with angiographic contrast medium resulted in a steeper diastolic pressure-flow velocity slope (0.80 vs 0.35 cm/s/mmHg, p<0.001) and a lower zero flow pressure intercept (p<0.05).
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