Evaluation of contractile function and inotropic reserve with tissue velocity, strain and strain rate imaging in streptozotocin-induced diabetes.
OBJECTIVE
The aim of the present study was to evaluate left ventricular (LV) function and contractile reserve (CR) with Doppler myocardial imaging (DMI) in a small animal model for type 1 diabetes.


RESULTS
Cardiac function was assessed in anaesthetized Wistar rats 6 and 8 weeks after injection of 60 mg/kg of streptozotocin. At 6 weeks of diabetes, colour DMI echocardiography was performed at rest and during incremental dosages of dobutamine (5, 10, 20 microg/kg/min). Left ventricular fractional shortening was decreased after 8 weeks of follow-up [36 +/- 5 (D) vs. 41 +/- 4% (C); P = 0.049]. After 6 weeks of diabetes, DMI measurements were reduced in the diabetic rats in the inferolateral wall at rest [systolic velocity: 2.5 +/- 0.4 (D) vs. 4.4 +/- 0.3 (C) cm/s; P < 0.001; systolic strain rate: 12.2 +/- 3.4 (D) vs. 17.4 +/- 3.2 (C) 1/s; P = 0.012] and during inotropic stimulation [delta velocity (cm/s): 0.2 +/- 0.1 (D) vs. 0.5 +/- 0.3 (C)/5 microg dobutamine; P = 0.002; delta strain rate (1/s): 1.4 +/- 0.9 (D) vs. 3.3 +/- 2.2 (C)/5 microg dobutamine; P = 0.049]. Furthermore, the intraventricular delay in time-to-peak systolic strain was larger in diabetes [20 +/- 18 (D) vs. 10 +/- 7 (C) ms; P= 0.01]. Systolic mitral annular velocity was also lower in the diabetic rats at rest [2.7 +/- 0.4 (D) vs. 3.5 +/- 0.4 (C) cm/s; P < 0.001] and in response to dobutamine [delta velocity (cm/s): 0.1 +/- 0.1 (D) vs. 0.3 +/- 0.2 (C)/5 microg dobutamine; P = 0.013].


CONCLUSIONS
In experimental diabetes, a reduction in radial and longitudinal LV function and CR can be detected with DMI before the onset of a reduced global LV function.
Weytjens
Caroline
C
Department of Cardiology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium. igwsc@uzbrussel.be
Cosyns
Bernard
B
D'hooge
Jan
J
Droogmans
Steven
S
Lahoutte
Tony
T
Garbar
Christian
C
Roossens
Bram
B
Van Camp
Guy
G
D000465:Algorithms; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000503:physiopathology*; D004195:Disease Models, Animal; D025401:Echocardiography, Stress / Q000379:methods; D008297:Male; D009200:Myocardial Contraction; D051381:Rats; D017208:Rats, Wistar; D013599:Systole; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology*