Usefulness and limitations of radiographic methods for determining left ventricular volume

The various methods currently being used to determine left ventricular chamber volumes from biplane angiocardiograms are described and discussed. The spatial direction and change of direction and length of the long axis of the left ventricle over the heart cycle is described. The long axis of the left ventricle is in most subjects directed approximately 20 degrees from being parallel with the frontal plane of the body and results in only slight foreshortening of the long axis of the left ventricle on films taken in the anteroposterior projection. A method is described and evaluated for determining left ventricular chamber volume from angiocardiograms taken in a single anteroposterior projection. Values for normal end-diastolic volume and systolic ejection fraction obtained by various investigators using the radiographic methods are given. The application of these radiographic methods to estimate aortic and mitral valve regurgitant flow is reviewed. Pressure-volu ne relations of the diastolic left ventricle have been determined in 176 patients and demonstrate large patient-to-patient differences of ventricular distensibility in patients with different types and durations of heart disease. Measurement of compliance of the diastolic left ventricle from the pressure-volume curves is discussed. By relating pressure and volume curves over the entire heart cycle, left ventricular pressure-volume curves can be constructed and from these the various components of pressure-volume work determined: systolic work, work done in distending the ventricle during diastole, and net work. Values obtained for these various components of ventricular work in patients with heart and valvular disease are discussed. A method for calculating wall tension and stress from measurement of chamber pressure and chamber dimensions is reviewed. Left ventricular mass can be calculated from chamber dimensions and wall thickness determined from angiocardiograms. A value of 92 ± 16 gm. has been obtained by this method in patients without left ventricular disease, and this is similar to values obtained in earlier postmortem studies. Measurement of left ventricular oxygen consumption and mechanical efficiency in patients with heart disease is discussed.