Fig. (18).

Intracoronary ECG (upper part) and pressure tracings (lower part) in a patient without evidence of myocardial ischemia during a 1-minute coronary balloon occlusion (left side; no ECG signs of ischemia, i.e., sufficient collaterals), and in a patient with marked ECG ST-segment elevations during the 1-minute coronary occlusion (right side; insufficient collaterals). Concomitantly, mean and phasic distal coronary pressure decreased much less during coronary occlusion (Poccl, red pressure curves) in the patient with sufficient collaterals than in the patient with insufficient collaterals (right side). Abbreviations: Pao: aortic pressure (black pressure curve); CVP: central venous pressure (black pressure curve).