Quantitation of regional cardiac function by two-dimensional echocardiography. I. Patterns of contraction in the normal left ventricle.

Abstract

SUMMARY Regional differences in wall motion and wall thickening were quantitated in the normal left ventricle using two-dimensional echocardiography (2-D echo). Using a computer-aided system, the left ventricle was subdivided in a standardized manner into 40 segments of five 2-D echo short-axis cross sections from the mitral valve level to the low left ventricle or apex. Measurements of sectional and segmental cavity areas, muscle areas and endocardial as well as epicardial peritneters, allowed assessment of contractile function using such indexes as endocardial systolic fractional area change (FAC), wall thickening (WTh), and circumferential fiber shortening (shortening). In 50 normal anesthetized, closed-chest dogs (including 10 studies in the conscious state) and in 32 normal humans, left ventricular contractile function increased significantly from base to apex. Thus, in anesthetized dogs, sectional FAC, WTh and shortening increased from left ventricular base to apex as follows: 39.4 ± 5.1% to 61.6 ± 7.2%, 20.5 ± 6.6% to 46.7 11.5% and 22.7 ± 3.4% to 35.4 5.9%, respectively. Similar trends were noted in conscious dogs. In man, sectional FAC, WTh and shortening also increased from the mitral valve to the low left ventricular level: 38.8 3.3% to 60.7 4.5%, 23.9 ± 5.6% to 28.9 ± 7.6% and 21.4 ± 5.0% to 30.6 ± 5.6%, respectively. Detailed segmental analysis in individual cross sections also revealed regional differences in contraction. Generally, contraction was most vigorous in posterior regions of the left ventricle. The septal regions exhibited lowest contraction at the base, but also the greatest increase from base to apex, both in the canine and human. Lateral regions did not show significant changes along the length of the left ventricle. Diastolic wall thickness also varied. We conclude that contraction in the normal left ventricle cannot be assumed to be uniform or symmetrical. These normal regional differences in function should be taken into account when evaluating altered physiologic states and in studying effects of therapeutic interventions.FOR MANY YEARS cardiologists have assumed that the pattern of contraction in the normal left ventricle is concentric and uniform, classically defined as synergic motion. i Most of the earlier studies aimed at characterizing ventricular function were therefore based on models and assumed myocardial fiber structure consistent with uniform contraction.2 3 However, animal investigations have shown that the distribution of fiber angles is complex and changes during systolic contraction; endocardial and epicardial fibers tend to be oriented longitudinally and midwall fibers circumferentially.4 A study by Greenbaum et al.5 indicates that the human cardiac fiber architecture is even more complex than previously thought. Thus, models based on uniform wall motion may not adequately describe LV function in normal states, a prerequisite for studying altered physiologic conditions. Clinical studies using cineventriculography in man have indicated that myocardial performance ...

Validity of echocardiographic determination of left ventricular systolic wall thickening.

“…This is an oversimplification. Anatomic considerations'5 and the recent study of Haendchen et al 16 suggest that left ventricular long-axis shortening is greater at the apex than at the base. If this is the case, then ES Myo CSA would be expected to be in close agreement with ED Myo CSA at the base, but to increasingly exceed ED Myo CSA toward the left ventricular apex.…”

Interaction between left ventricular wall motion and intraventricular flow propagation in acute and chronic ischemia

“…Furthermore, a heterogenetic wall motion pattern can also be found in normal hearts (1,13,23). An augmentation of the normal IVR velocities directed toward the apex has been found in patients with hyperdynamic ventricles (25).…”

Ultrasonic Backscatter and Serum Marker of Cardiac Fibrosis in Hypertensives

“…Furthermore, quantitative differences in CV observed among the different myocardial regions have been found to be associated with corresponding regional differences in contractile performance. 31 Thus, it is possible that reduced systolic function in hypertensive patients with PIP above 127 g/L is in part responsible for the observed reduction in CV. The role of myocardial fibrosis in this patient population can be considered as determinant of this functional abnormality.…”