Myocardial perfusion MRI shows impaired perfusion of the mouse hypertrophic left ventricle

There is growing consensus that myocardial perfusion deficits play a pivotal role in the transition from compensated to overt decompensated hypertrophy. The purpose of this study was to systematically study myocardial perfusion deficits in the highly relevant model of pressure overload induced hypertrophy and heart failure by transverse aortic constriction (TAC), which was not done thus far. Regional left ventricular (LV) myocardial perfusion (mL/min/g) was assessed in healthy mice (n = 6) and mice with TAC (n = 14). A dual-bolus first-pass perfusion MRI technique was employed to longitudinally quantify myocardial perfusion values between 1 and 10 weeks after surgery. LV function and morphology were quantified from cinematographic MRI. Myocardial rest perfusion values in both groups did not change significantly over time, in line with the essentially constant global LV function and mass. Myocardial perfusion was significantly decreased in TAC mice (4.2 ± 0.9 mL/min/g) in comparison to controls (7.6 ± 1.8 mL/min/g) (P = 0.001). No regional differences in perfusion were observed within the LV wall. Importantly, increased LV volumes and mass, and decreased ejection fraction correlated with decreased myocardial perfusion (P < 0.001, in all cases). Total LV blood flow was decreased in TAC mice (0.5 ± 0.1 mL/min, P < 0.001) in comparison to control mice (0.7 ± 0.2 mL/min). Myocardial perfusion in TAC mice was significantly reduced as compared to healthy controls. Perfusion was proportional to LV volume and mass, and related to decreased LV ejection fraction. Furthermore, this study demonstrates the potential of quantitative first-pass contrast-enhanced MRI for the study of perfusion deficits in the diseased mouse heart.

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