Echocardiography assessment of myocardial function after burn injury

Echocardiography provides noninvasive and clinically relevant assessment of left ventricle (LV) function in injury and disease. In this present study, we hypothesized that application of transthoracic echocardiography in awake mice would provide in vivo assessment of myocardial performance that correlates with in vitro assessment of LV function using isolated perfused hearts (Langendorff).

Burn over 40% of the total body surface area (or sham burn) was given in C57/BL6 mice 22 to 24 g; lactated Ringer fluid resuscitation was given intraperitoneally. Transthoracic echocardiography was performed at baseline and at designated intervals over 7 days postburn. Subgroups of mice were killed at intervals and hearts perfused to assess LV pressure and +/-dP/dt max responses to inotropic challenge (n = 8/group per time).

Burn produced myocardial depression, evidenced by a fall in fractional shortening from 69% +/- 3% at baseline to 50% +/- 2% (12 h postburn), 58% +/- 3% (24 h), 59% +/- 2% (48 h), and 62% +/- 2% (72 h) (P < 0.05). Burn-related changes in in vivo LV performance were paralleled by in vitro evidence of myocardial contractile depression; LV pressure progressively fell from 97 +/- 2 mmHg at baseline to 84 +/- 7 mmHg (12 h), 63 +/- 2 (24 h), 79 +/- 4 mmHg (48 h postburn) (P < 0.05). Analysis of variance and multiple comparison procedure. Myocardial recovery occurred by day 8 postburn.

Echocardiography provides measures of cardiac function in a conscious animal, which correlate with contractile depression measured in vitro using Langendorff preparations. Echocardiography is a valuable tool for noninvasive assessment of postburn myocardial function.