End-systolic stress-velocity and pressure-dimension relationships by transthoracic echocardiography in mice

RV Williams, JN Lorenz, SA Witt… - American Journal …, 1998 - journals.physiology.org
RV Williams, JN Lorenz, SA Witt, DT Hellard, PR Khoury, TR Kimball
American Journal of Physiology-Heart and Circulatory Physiology, 1998journals.physiology.org
The purposes of this study were to assess load-independent, end-systolic relationships in
mice and compare these relationships to ejection phase indexes in assessing contractility. In
13 mice, ejection phase indexes (shortening fraction and velocity of fiber shortening) and
end-systolic relationships [pressure-dimension relationship (ESPDR) and stress-velocity
relationship (ESSVR)] were determined using M-mode echocardiography and simultaneous
left ventricular pressure. Load was altered with phenylephrine and nitroprusside …
The purposes of this study were to assess load-independent, end-systolic relationships in mice and compare these relationships to ejection phase indexes in assessing contractility. In 13 mice, ejection phase indexes (shortening fraction and velocity of fiber shortening) and end-systolic relationships [pressure-dimension relationship (ESPDR) and stress-velocity relationship (ESSVR)] were determined using M-mode echocardiography and simultaneous left ventricular pressure. Load was altered with phenylephrine and nitroprusside. Contractility was increased with dobutamine and decreased by induction of hypothyroidism. Ejection phase indexes increased with dobutamine infusion but were not significantly decreased with hypothyroidism. However, end-systolic relationships changed significantly with both dobutamine (y-intercepts: ESPDR from 22 to 48 mmHg, ESSVR from 3.7 to 6.6 circ/s,P < 0.05) and hypothyroidism (y-intercepts: ESPDR from 22 to 11 mmHg, ESSVR from 3.7 to 3.2 circ/s, P< 0.05). We conclude that end-systolic indexes can be accurately measured in the intact mouse by echocardiography with simultaneous left ventricular pressure recording and appear to be more sensitive to inotropic state than ejection phase indexes.
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