Comparison of two techniques for measuring two-dimensional strain
in the rat left ventricle.
Omens, Jeffrey H., Dyan D. Farr, Andrew D. McCulloch, and Lewis K.
Waldman.
Departments of Medicine (Cardiology)1 and Bioengineering
APStracts 3:0042H, 1996.
Measurements of regional deformation in the left ventricle are needed
to understand the structural basis of ventricular function. Two
techniques were employed to measure two-dimensional strain in the
intact, beating rat heart. Rats were anesthetized and ventilated, and
the chest opened. Homogeneous two-dimensional strains were measured
during the cardiac cycle relative to end-diastole with either a
triangle of miniature (0.3-0.5 mm) piezoelectric crystals implanted
at midwall, or with 3 epicardial surface markers imaged with 60 Hz
video. Average heart rate was 303+/-37 beats/min, end-diastolic
pressure 2+/-2 mmHg and peak-systolic pressure 106+/-31 mmHg in all
of the hearts. In general, strains during the cardiac cycle showed
similar trends to those previously reported in the dog. The
magnitudes of peak systolic cardiac strains on the epicardium and at
midwall were -0.076+/-0.055, -0.068+/-0.014 (circumferential),
-0.102+/-0.040, -0.082+/-0.039 (longitudinal), and 0.065+/-0.016,
0.064+/-0.043 (in-plane shear). These new techniques will allow
measurements of regional systolic cardiac function in rats with
pathological interventions or genetic modifications that may alter
regional ventricular function.
Received 5 September 1995; accepted in final form 4 January 1996.
APS Manuscript Number H835-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 January 96