Passage of Ultrasound Contrast Medium (Gas Bubbles) into the Cerebral Circulation
Ultrasound contrast medium containing microbubbles now is usually used for cardiologic examinations. After intravenous injection, the gas bubbles reach the right ventricle and a small portion of them after passage of the lung also reach the left ventricle and the aorta. To determine the amount of gas bubbles passing the cerebral arteries after i.v. injection of ultrasound contrast medium, we examined 10 patients during echocardiographic examinations with transcranial Doppler sonography of the middle cerebral artery. The amount of echoes depended on the dose of contrast medium administered and varied between different individuals, probably because of av shunts in the lung. In patients with septal defects, however, tremedous showers of ultrasound-reflecting gas bubbles can be demonstrated in the cerebral arteries. By now, even in these patients no side effects or complications were observed apart from transient sensations of taste. Therefore, it may be possible to inject this type of ultrasound contrast medium without greater risk into the arterial system and even into cerebral arteries.