We have previously reported the potential use of intracardiac echocardiography (ICE) in a variety of clinical settings, including detection of pericardial effusion, intracardiac masses, congenital cardiac defects, and during simulated balloon valvuloplasty. The utility of intracardiac ultrasound imaging of the left ventricle (LV) in patients with coronary disease needs to be further explored. We performed this study with the purpose of evaluating risk area and regional wall-motion abnormalities produced by ischemia using ICE. Ten episodes of ischemia were produced by transiently occluding the left anterior descending coronary artery in five dogs. ICE was performed with a modified 5-MHz transesophageal echocardiographic probe placed in the right atrium. Continuous short-axis images of the LV were obtained before, during, and after coronary occlusion. Risk area was defined using myocardial contrast echocardiography. In all cases, ICE provided high resolution images of the LV. Risk area and regional wall-motion abnormalities were readily detected. There was good correlation between the risk area (x) and extent of dyssynergy (y), defined by the equation y = 0.76x + 6.38 (r = 0.80, P less than 0.01). We conclude that ICE provides potentially useful information concerning regional LV dysfunction, and, when combined with myocardial contrast echocardiography, area at risk. This technique may be useful during interventional procedures once a catheter-based ultrasound transducer with adequate depth of field to provide images of the entire LV can be developed.