Complications following percutaneous transluminal coronary angioplasty (PTCA), such as coronary artery occlusion, spasm, or dissection, frequently require urgent surgical intervention. Out of 26 patients from our hospital, 12 who underwent emergency coronary bypass grafting because of balloon catheter complications with a total ischemic time of 100-255 min, were restudied in the late postoperative period by clinical examination and by coronary and left ventricular angiography. Left ventricular angiograms were evaluated quantitatively for global and regional function using the AVD system (Siemens Elema, Erlangen). Electronmicroscopic results from myocardial biopsy samples, taken intraoperatively from the presumed center of the ischemic zone, were compared with the clinical results. An improvement of left ventricular function parameters could be seen in patients with reperfusion intervals within 130 min. In the case of intermittent perfusion of the occluded vessel (catheter perfusion with arterial blood, intermittent spasm) operative revascularization proved to salvage jeopardized myocardium. There was a close correlation between the degree of left ventricular dysfunction and histological results, coronary morphology and clinical staging. In conclusion, the efficacy of myocardial protection by emergency bypass surgery depends mainly on coronary morphology and above all on reperfusion intervals.