LEFT-VENTRICULAR CONTRACTION PATTERN CHANGES WITH AGE IN NORMAL ADULTS

Left ventricular ejection fraction is known to be unchanged or slightl y increased with advancing age. This echocardiographic study, includin g 40 healthy subjects 18 to 70 years old, shows that this is a net eff ect of decreased contractions in the long axis and increased in the sh ort axis. From age 18 to 70 years, the longitudinal shortening decreas es by 2056 (P < .001) and the short-axis diameter shortening increases by 18% (P = .012). Multiple regression analysis showed strong correla tion to age for both short- and long-axis contractions and no signific ant additional explicatory power when the variables systolic blood pre ssure, left ventricular wall thickness, heart rate, or sex were includ ed. There was no significant correlation between diameter changes duri ng the isovolumic phases and age. The findings have practical implicat ions when calculating ejection fraction from M-mode measurements. Teic hholz's formula will overestimate ejection fraction in elderly subject s, and calculation of ejection fraction from mitral ring motion will o verestimate it ill young subjects.