Clin. Cardiol. 7, 7(r85 (1984) © Clinical Cardiology Publishing Co., Inc. Echocardiographic Evaluation of Responses to Left Ventricular Volume Loading by Principal Components and Nomographic Analysis D. A. CONETIA, M.D., R. L. CARTER, Ph.D.,* E. A. GEISER, M.D., C. R. CONTI, M.D. Department of Medicine, *Department of Biostatistics, University of Florida, Gainesville, Florida, USA summary: Changes in perfonnance of left ventricles (LV) with volume overloads are difficult to detennine by conventional clinical methods. This infonnation, how- ever, is important for the proper timing of therapeutic interventions to preserve LV function. Seven size- adjusted (by regression with end-diastolic diameter, EDD) LV perfonnance parameters from 100 nonnal echocardiograms (echos) were entered into a principal component analysis (PCA). Two factors (linear com- bination of the 7 parameters) were obtained from the analysis. Prediction limits (95 %) about these two factors used in combination, correctly classified 92 % of the nor- mal echos. More detailed analysis of the two PCA fac- tors revealed that the majority of the variability within the factors was explained by size-adjusted parameters resultant from the EDD posterior wall (factor 1) and EDD septal excursion (factor 2) regressions, respective- ly. Plots of the 95 % prediction limits about these two regression lines provided nomograms. These nomo- grams used in combination, correctly classified 95 % of the normal echos. When the performance parameters of 64 volume loaded ventricles were evaluated by PCA, four groups were identified. Ten ventricles (16%) were hypokinetic, 29 (45%) were hyperkinetic, 23 (36%) were nomokinetic, and 2 (3%) could not be classified. Address for reprints: Donald A. Conetta, M.D. Department of Medicine University of Florida Box J-277, JHM Health Center Gainesville, FL 32610, USA Received: April 4, 1983 Accepted with revision: October 18, 1983 These classifications were supported by significant be- tween group differences of shortening fraction, velocity of circumferential shortening, and velocity of circum- ferential expansion. Nomographic classification of the same volume loaded hearts was in excellent (94 %) agreement with PCA classification. Nomographic analy- sis (derived from the PCA) is offered as a less complex, more clinically applicable echo method for evaluating LV perfonnance of volume loaded hearts. Key words: LV volume overloaded, LV function, prin- ciple components analysis, nomographic analysis Introduction Evaluation of left ventricular perfonnance of indi- vidual patients with aortic and mitral regurgitation by history, physical examination, ECG, and chest x-ray in the absence of congestive heart failure is difficult. How- ever, it is most desirable to recognize LV perfonnance changes prior to the onset of s)Ullptoms in order to be able to minimize significant loss of myocardial function. The original echocardiographic (Stone et al., 1969) and many hemodynamic studies (Cohn et al., 1969; Eckberg etal. , 1973; Kennedyetal., 1968,1970,1977; Vokonas et al., 1973) of volume-loaded ventricles have related single parameter measurements to angiographic regurgitant fractions rather than ventricular function in- dices. Subsequent echo studies have related parameters of LV performance to symptoms of congestive heart failure and hemodynamic function (McDonald, 1976a, b; Rosenblatt et al., 1976). Although the latter studies have used echocardio- graphic parameters to identify patterns of ventricular per- formance in groups of patients, no method of classifying ventricular function in an individual patient has been developed.