Quantitative assessment of regional myocardial function in mice by tissue Doppler imaging: comparison with hemodynamics and sonomicrometry.
BACKGROUND
Tissue Doppler imaging (TDI) is a novel echocardiographic method to quantify regional myocardial function. The objective of this study was to assess whether myocardial velocities and strain rate (SR) could be obtained by TDI in mice and whether these indices accurately quantified alterations in left ventricular (LV) systolic function.


RESULTS
TDI was performed in 10 healthy mice to measure endocardial (v(endo)) and epicardial systolic velocities and SR. In further experiments, TDI indices were compared with dP/dt(max) and with sonomicrometer-derived regional velocities, at rest and after administration of dobutamine or esmolol. TDI indices were also studied serially in 8 mice before and 4 and 7 hours after endotoxin challenge. Myocardial velocities and SR were obtained in all mice with low measurement variability. TDI indices increased with administration of dobutamine (v(endo) from 2.2+/-0.3 to 3.8+/-0.2 cm/s [P<0.01]; SR from 12+/-2 to 20+/-2 s(-1) [P<0.05]) and decreased with administration of esmolol (v(endo) 1.4+/-0.2 cm/s [P<0.05]; SR 6+/-1 s(-1) [P<0.01]). Both indices correlated strongly with dP/dt(max) (r2=0.79 for SR and r2= 0.69 for v(endo); both P<0.0001). SR and shortening fraction were predictors of dP/dt(max) even after adjustment for the confounding effect of the other variables. V(endo) correlated closely with sonomicrometer-measured velocity (r2=0.71, P<0.0005). After endotoxin challenge, decreases in both v(endo) and SR were detected before decreases in shortening fraction became manifest.


CONCLUSIONS
Myocardial velocities and SR can be measured noninvasively in mice with the use of TDI. Both indices are sensitive markers for quantifying LV global and regional function in mice.
Sebag
Igal A
IA
Cardiac Ultrasound Laboratory in the Cardiology Division of the Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Mas 02114, USA.
Handschumacher
Mark D
MD
Ichinose
Fumito
F
Morgan
John G
JG
Hataishi
Ryuji
R
Rodrigues
Ana Clara T
AC
Guerrero
J Luis
JL
Steudel
Wolfgang
W
Raher
Michael J
MJ
Halpern
Elkan F
EF
Derumeaux
Geneviève
G
Bloch
Kenneth D
KD
Picard
Michael H
MH
Scherrer-Crosbie
Marielle
M
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology; D015150:Echocardiography, Doppler / Q000379:methods / Q000592:standards; D004731:Endotoxins / Q000494:pharmacology; D006334:Heart Function Tests; D006339:Heart Rate; D007700:Kinetics; D051379:Mice; D009068:Movement; D011412:Propanolamines / Q000494:pharmacology; D015203:Reproducibility of Results; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis*
D002316:Cardiotonic Agents; D004731:Endotoxins; D011412:Propanolamines; D004280:Dobutamine; C036604:esmolol