[Determination of the ejection fraction of the left ventricle by videodensitometric analysis of digital angiography. Preliminary results].

Digitalisation enables angiocardiography to be performed by a peripheral intravenous injection. Computer-assisted analysis of the date widens the possibilities of quantification. The authors have developed a videodensitometric method of studying the left ventricular ejection fraction. The research was performed on an experimental model and the technique validated in a series of 10 patients. The experimental model consisted of a series of balloons which, when inflated with contrast medium assumed an allipsoid shape resembling a left ventricle. The balloons were blown up in two stages with an automatic injector to simulate systole and diastole. The images were recorded in the same way as during ventriculography. Videodensitometric measurements showed 3 to 5% variations from the true values. The method was then applied to the calculation of the left ventricular ejection fraction in 10 patients: left ventricular function was also quantified by geometrical methods (Dodge) from the same angiogrammes and the 2 sets of results were then compared. The correlation coefficient between the two methods was 0.97, so validating the new technique. Videodensitometry opens up new perspectives in the study of left ventricular function. On the other hand it can be used to monitor the ejection fraction in severely ill or recently operated patients, and, on the other hand the principle of videodensitometry eliminates the geometrical approximations inherent in the classical methods of angiographic analysis and would therefore seem to be more suitable for the study of pathological left ventricules (aneurysm...). Finally, the technique of videodensitometry represents a new step towards the measurement of true volumes and flow rates.