Echocardiographic imaging of the left ventricle by peripheral intravenous injection of echo contrast agent

With the use of a new echo contrast agent (ECA) that consists of a suspension with microbubbles (100% less than 3.9 micron in a moving system), we were able to opacify the left ventricle by peripheral intravenous injection in 124 of 130 patients (95%) without shunt connection. In 12 patients with aortic valve disease we measured the opacification of the right and left ventricles videodensitometrically by means of increasing doses. Dose 1 (8.7 ml ECA) and dose 4 (50 ml ECA) led to no significant difference in intensity in the right ventricle (168 +/- 32 vs 184 +/- 16 units, respectively; p greater than 0.05); however, opacification of the left ventricle was significantly more evident after dose 4 (60 +/- 60 vs 88 +/- 62 units, respectively; p less than 0.05). On the basis of the farthest distance reached by the regurgitant microbubbles from the aortic valve, the severity of regurgitation was graded on a four-point scale; the results were compared with those of aortography. A significant correlation (r = 0.98, n = 9) was found between ECA grading and aortography in the evaluation of the severity of aortic insufficiency. In addition, flow characteristics in patients with mitral stenosis, aortic insufficiency, and the regurgitation jet in incompetent aortic prosthesis in connection with diastolic inflow over the mitral valve were described. Moreover, it was possible to differentiate between inflow of ECA into the left atrium via an atrial septal defect and across the pulmonary vascular bed. No adverse effects were reported by the patients. Left ventricular end-diastolic volume index, end-systolic volume index, stroke volume index, and ejection fraction were determined before and after intravenous injection of increasing doses of ECA by means of the area-length method of Sandler and Dodge. Even after dose 4 we observed no significant changes in left ventricular function. The values before and after injection were in the range of intra- and interobserver reproducibility. Only three patients reported a slight taste sensation. In nine patients with a history of allergies there were no side effects.