Systolic functional response of normal older and younger adult left ventricles to dobutamine.

To determine the systolic functional response of the aged left ventricle to catecholamines, 16 healthy, physically active subjects aged 62 to 72 years (group A) and 19 healthy adults aged 18 to 28 years (group B) were evaluated before and during infusion of 8 micrograms/kg/min of dobutamine. Phonocardiograms, electrocardiograms and M-mode echocardiograms were recorded simultaneously with a carotid pulse tracing. End-diastolic dimension and end-systolic pressure remained unchanged in the 2 groups. End-systolic dimension decreased 0.3 cm (p less than 0.001) in group A and 0.5 cm (p less than 0.001) in group B. Fractional shortening increased (p less than 0.001) from 34 +/- 4% to 38 +/- 5% in group A and from 34 +/- 4% to 43 +/- 4% in group B. Mean velocity of circumferential fiber shortening (Vcf) increased 0.6 circ/s (p less than 0.001) in group A and 1 circ/s (p less than 0.001) in group B. End-systolic pressure/dimension ratio increased 3 mm Hg/cm (p less than 0.001) in group A and 8 mm Hg/cm (p less than 0.001) in group B. The changes in end-systolic dimension, fractional shortening, Vcf and end-systolic pressure/dimension ratio were more significant in group B (p less than 0.001). Thus, the left ventricular systolic functional response to dobutamine is diminished in healthy older persons.