Myocardial ischemia in dog was induced with releasable material in the distal segment of the anterior descending branch of the left coronary artery. Three releasable materials were tested: gel foam, wax microspheres (120-200 mu m) and latex balloons, using different methods of introduction. The left carotid route was selected for introduction of a performed catheter. The gel foam and wax microspheres caused transitory ischemia, which was proximal for the foam and distal for the microspheres. The balloons made is possible to standardize the ischemia as its localization and duration could be selected. This material therefore provided a model for stable chronic ischemia. Nine dogs were observed by means of precordial mapping (36 electrodes) during the phase following ischemia or for a period of 4 weeks. The results of these experiments are analyzed and correlated with histological results for the post-mortem phase.