Quantification of collateral blood flow during PTCA by intravascular Doppler

The assessment of flow velocity using the Doppler guidewire provides a means of investigating both antegrade and retrograde blood flow in the coronary artery distal to obstructive lesions and occluding PTCA balloons. This has yielded unique qualitative and quantitative information regarding coronary collateral blood flow, and the responses of collaterals to pharmacological and haemodynamic perturbations. The current study analysed collateral flow velocity recordings obtained during coronary interventions in 46 patients in our laboratory. The mean collateral peak velocity integral distal to the occluding PTCA balloon was 9 +/- 7 units, while antegrade distal coronary peak velocity integral following stenosis relief by PTCA was 27 +/- 12 units. Thus, during PTCA balloon occlusion collaterals were able to supply a mean of 30 +/- 18% of the flow provided antegrade by successful PTCA. Variability in collateral flow velocity was not accounted for by differences in the PTCA artery assessed, the supply artery, the direction of collateral filling, the severity of coronary stenosis, or the angiographic grade of collaterals, and the magnitude of collateral flow velocity did not correlate with preserved left ventricular regional wall motion. The measurement of collateral flow velocity by intravascular Doppler provides unique and quantitative information regarding the coronary collateral circulation.