LV systolic performance improves with development of hypertrophy after transverse aortic constriction in mice

Transverse aortic constriction (TAC) is an effective technique for inducing left ventricular (LV) hypertrophy in mice. With the use of transthoracic e chocardiography and Doppler measurements, we studied the effects of an acut e increase in pressure overload on LV contractile performance and peak syst olic wall stress index (WSI) at early time points after TAC and the time co urse of the development of LV hypertrophy in mice. The LV mass index was si milar between TAC and sham-operated mice at postoperative day 1 but progres sively increased in TAC mice by day 10. There was no further increase in th e LV mass index between postoperative days 10 and 20. On day 1, whereas pea k systolic WSI increased significantly, the LV ejection fraction (LVEF) and percent fractional shortening (%FS) decreased in TAC mice compared with sh am-operated mice. By day 10, peak systolic WSI, LVEF, and %FS had recovered to baseline levels and were not significantly different between postoperat ive days 10 and 20. Thus LV systolic performance in mice declines immediate ly after TAC, associated with increased peak systolic WSI, but recovers to baseline levels with the development of compensatory LV hypertrophy over 10 -20 days.