QUANTIFICATION OF RECRUITABLE CORONARY COLLATERAL BLOOD-FLOW IN CONSCIOUS HUMANS AND ITS POTENTIAL TO PREDICT FUTURE ISCHEMIC EVENTS

Objectives. The present study was designed to evaluate the applicabili ty of a pressure-flow equation for quantitative calculation of recruit able collateral blood flow at coronary artery occlusion in conscious p atients and to investigate the value of that index to predict future i schemic events. Background. Recent experimental studies have indicated that recruitable collateral blood flow at coronary artery occlusion c an be expressed as a fraction of normal maximal myocardial blood flow by simultaneous recordings of mean arterial, coronary wedge and centra l venous pressures, respectively. This index is called the pressure-de rived fractional collateral bow and is independent of hemodynamic load ing conditions. Methods. In 120 patients undergoing elective coronary angioplasty, mean arterial, coronary wedge and central venous pressure s were measured at balloon inflations of 2 min. All patients had a rec ent exercise electrocardiogram (ECG) with positive findings showing cl early distinguishable, reversible ECG abnormalities, enabling recognit ion of ischemia at balloon inflation. Fractional collateral blood flow at angioplasty was calculated by coronary wedge pressure minus centra l venous pressure divided by mean arterial pressure minus central veno us pressure and correlated to the presence or absence of ischemia at b alloon inflation. Ischemic events were monitored during a follow-up pe riod of 6 to 22 months. Results. In 90 of the 120 patients, ischemia w as present at balloon inflation, and in 82 of these patients, fraction al collateral blood flow was less than or equal to 23%. By contrast, i n 29 patients, no ischemia was present, and fractional collateral bloo d how was >24% in all 29. During the follow-up period, 16 patients had an ischemic event. Fifteen of these 16 patients were in the group wit h insufficient collateral flow (p < 0.05). Conclusions. To our knowled ge, this study presents the first method for quantitative assessment o f recruitable collateral blood flow in humans in the catheterization l aboratory. Sufficient and insufficient collateral circulation can be r eliably distinguished by this method. Use of this method can also help to provide more insight into the extent and behavior of the collatera l circulation for investigational purposes and may have potential clin ical implications.