Vascular adaptations to transverse aortic banding in mice

Transverse aortic banding in mice generates pressure overload, but cardiac hypertrophy is variable, and the effects on peripheral hemodynamics are unknown. The purpose was to characterize and model carotid and aortic blood flow patterns in banded mice using noninvasive Doppler methods. In 15 normal mice a 27-gauge needle was sutured against the transverse aorta and then removed. In 6 sham-operated mice the suture was not tied. A Doppler probe was used to measure right (R) and left (L) carotid artery (CA), aortic, and mitral blood velocity 1 day later. At 7 days the heart-weight/body-weight ratio (HW/BW) was measured. Mean aortic, mitral, and carotid velocities were similar in sham and banded mice, but peak RCA/LCA velocities were much higher in banded mice and were highly correlated to HW/BW. An esophageal Doppler probe detected high jet velocity and distal vorticity. We conclude that mice compensate for the band by increasing RCA resistance and compliance and decreasing LCA resistance to maintain normal cerebral perfusion. Velocity signals measured within one day and fitted to a lumped-parameter arterial model to estimate the pressure drop can predict the amount of cardiac hypertrophy at one week.