Alterations of coronary collateral blood flow velocity during intraaortic balloon pumping

Controversy exists regarding the ability of intraaortic balloon pumping to increase coronary blood flow either directly or through collateral perfusion.^1-4 In patients, directly measured coronary flow velocity by intracoronary Doppler guidewire technique distal to severe coronary stenoses is minimal and unaffected by intraaortic balloon pumping.⁵ After coronary angioplasty, intraaortic balloon pumping increases both proximal and, more importantly, distal coronary artery flow velocity.⁵ Whether collateral flow is altered during intraaortic balloon pumping has not been adequately studied in humans because of a lack of quantitative means to assess collateral blood flow.⁶ With the use of a Doppler-tipped angioplasty guidewire, retrograde collateral flow velocity can be directly measured, and thus quantitate the effects of interventions altering collateral blood flow responses. ⁷ While performing angioplasty with the Doppler guidewire, we quantitated intracoronary collateral blood flow alterations during intraaortic balloon pumping in 3 patients: 2 with acute myocardial infarction and 1 with unstable angina. These observations using flow velocity techniques to evaluate perturbations of collateral flow are the first physiologic demonstrations in patients of one of the unique hypothesized beneficial antiischemic mechanisms of intraaortic balloon pumping.