[Echocardiography in the evaluation of ventricular function].

The ultrasonic beam used for quantitative assessment of left ventricular (LV) function traverses the heart in a projection similar to the familiar angiographic left anterior oblique projection. It crosses the anterior wall of the right ventricle, the right ventricular cavity, the interventricular septum, the LV cavity and the posterior wall of the left ventricle. Whereas the cyclic changes of the right ventricular diameter are rarely clearly determined by echocardiography, the easily assessed cyclic changes of the LV endocardial transverse diameter are useful measure of LV FUNCTION. Of practical importance are the percentage of systolic shortening of the LV diameter (%Sh) and the mean velocity of circumferential fiber shortening (VCF). There are several factors, such as placing of the ultrasonic transducer, the shape and size of the LV cavity and rotational movements of the heart as a whole, that influence echocardiographic determination of the transverse LV diameter. In patients with asynergic contraction, %Sh and VCF cannot be used as measures of overall LV performance, but localized contraction disturbances of the septum and the posterior wall may be detected from the reduced extent of wall motion in a given LV segment during a full sweep from the base to the apex. The most important indications for echocardiographic assessment of LV function are valvar diseases with chronic LV pressure or volume overload, and congestive cardiomyopathy. Echocardiography has proved useful in serial evaluation of LV function in patients undergoing valvar heart surgery. Assessment of LV volume by standard echocardiography using the cubic formula is not satisfactory. More accurate determination of volumes is provided by formulas that include the actual ratio of the LV long axis to the minor axis.