The purpose of this study was to observe ventricular wall motion in myocardial ischemia and to image coronary artery flow by transvenous intracardiac two-dimensional echocardiography. Ten mongrel dogs (body weight 24-34 kg) were anesthetized by intravenous sodium pentobarbital (25 mg/kg) and ventilated using a Harvard respirator after tracheotomy. Real-time Doppler two-dimensional echocardiography (ALOKA SSD-870) and a transesophageal probe (5 MHz, 24 elements, diameter 6.8 mm, phased array transducer) were used. The probe was introduced into the right atrium via the femoral vein. Myocardial ischemia was induced under fluoroscopic control by the inflation of a balloon catheter in the coronary artery, or by beads embolization of the coronary artery in closed-chest dogs, or by ligation of the coronary artery after a left or right thoracotomy. The wall motion of the right and left ventricles was observed by using the probe positioned in the lower right atrium. Visualization of the coronary artery and the flow velocity were studied with the probe in the mid right atrium. 1) Imaging: The left coronary artery, left main coronary artery and left anterior descending artery were easily observed by the probe positioned in the mid right atrium. The blood flow velocity in the left main coronary artery was consistently recorded. Changes in the blood flow velocity by coronary vasodilators such as dipyridamole, isosorbide dinitrate and nicorandil were clearly detected. 2) Detection of the myocardial ischemia: During the right coronary artery occlusion the right ventricle showed marked dilatation and hypokinesis, and the interventricular septum showed paradoxical movement and was displaced towards the left ventricular cavity.(ABSTRACT TRUNCATED AT 250 WORDS)