Quantitative analysis of segmental wall motion during maximal upright dynamic exercise: variability in normal adults.

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Abstract
Twenty-five healthy adults underwent subcostal-view, four-chamber two-dimensional echocardiographic examination while upright at rest and at the peak of maximal bicycle exercise. The purpose of the study was to determine whether the variability in regional left ventricular endocardial motion, previously demonstrated to be present at rest, persisted at peak exercise. The rest and exercise end-diastolic and end-systolic endocardial contours were visually identified, digitized, and divided into 32 radial segments after realignment by the computer. At rest there was similar percent segmental area reduction for the septum (segments 1 to 12) (54 +/- 4%, mean +/- 1 SD), apex (segments 13 to 20) (67 +/- 3%), and lateral wall (segments 21 to 32) (67 +/- 8%). At peak exercise the percent area reduction increased significantly: septum 84 +/- 5%, apex 88 +/- 2%, lateral wall 83 +/- 6% (p less than .001 compared with rest for all areas). However, there was considerable variability in percent area reduction between different radial segments in the same individual. At rest the difference between minimal and maximal percent area reduction within the same individual was 49 +/- 17 percentage units (range 21 to 83) and that at peak exercise was 32 +/- 17 percentage units (range 0 to 66). It is concluded that, because the range of standard deviation of normal endocardial motion and the degree of variability between radial segments in the same healthy individual are significant, qualitatively determined "hypokinesis," as commonly assessed clinically, may be a normal event. However, segmental akinesis or dyskinesis, which occurred rarely at rest and never at peak exercise, must be considered abnormal events.

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