In nine pentobarbital anesthetized dogs, the global effects of bupivacaine on the heart were examined during and after the onset of bupivacaine cardiotoxicity. The onset of bupivacaine cardiotoxicity was followed by the use of echocardiography to determine the sequence of events. The overall sequence of changes in the heart, demonstrated by the echocardiographic images, was markedly impaired systolic function and right ventricular dilation. The right ventricular dilation was so profound that it was associated with a septal shift into the left ventricle. Right ventricular dilation was so profound that the ability to maintain the whole ventricle within the echocardiographic image was lost. Areas obtained from the left ventricle at the two time points studied (the half-time from the beginning of injection to the occurrence of asystole referred to as midway through the toxic episode and at asystole) exhibited a significant systolic dilation only midway through the toxic episode. The mean total dose of bupivacaine resulting in the dilation of the ventricles was 14.0 +/- 3.3 mg/kg. The mean arterial pressure was reduced from control by 46.9% +/- 8.8% midway through the toxic episode. The mean pulmonary arterial pressure exhibited no significant change from before the bupivacaine injection sequence. A variety of conduction changes seen midway through the toxic episode were widening of the QRS complex, inversion, bradycardia, premature ventricular contractions (PVCs), or a combination of these. PVCs, if seen at all, were only beginning to develop and no heart block was seen in any dog midway through the toxic episode.(ABSTRACT TRUNCATED AT 250 WORDS)