The potentially ischemia-protective effect of ECG-synchronized coronary venous retroperfusion (SRP) with arterial blood via the coronary sinus (CS) was assessed in 26 patients (56 +/- 10 years, 22 male, 4 female) in the clinical scenario of PTCA of a proximal LAD stenosis. In six additional patients the SRP procedure failed due to anatomical or technical reasons. In an intraindividual comparison at least two standardized balloon inflations for 60 seconds at 6-8 atm were performed in randomized order with and without continuous SRP at a flow rate of 200 +/- 46 ml/min. Under both conditions echocardiographic regional wall motion, ST depression in leads V1-6, hemodynamic parameters and symptoms expressed in a pain score were continuously monitored during angioplasty. This study revealed that the echocardiographic regional wall motion score in the perfusion territory of the dilated artery increased from 1.65 +/- 1.81 at baseline to 5.65 +/- 2.88 (p < 0.001) during a one minute dilatation without SRP. With SRP-support the regional wall motion at 1 minute angioplasty was significantly improved to 3.55 +/- 2.80 (p < 0.025). Moreover, the ischemic ECG-changes were markedly less pronounced, whereas the subjective perception of anginal pain was not different as a function of SRP-support. Thus, the simultaneous coronary venous retroperfusion with arterial blood has ischemia-protective potential in elective PTCA of a proximal LAD stenosis and may reduce ischemic dysfunction with prolonged balloon inflations.