Reant Patricia, Metras Alexandre, Detaille Dominique, Reynaud Annabel, Diolez Philippe, Jaspard-Vinassa Beatrice, Roudaut Raymond, Ouattara Alexandre, Barandon Laurent, Dos Santos Pierre, Lafitte Stephane
INSERM U1045, Pessac, France; Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France; IHU Liryc, Pessac, France.
Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France; INSERM U1034, Adaptation Cardiovasculaire à l'Ischémie, Pessac, France.
J Am Soc Echocardiogr. 2016 Dec;29(12):1217-1228. doi: 10.1016/j.echo.2016.09.006. Epub 2016 Oct 14.
Left ventricular (LV) afterload could be associated with reduced myocardial contractility. The aim of this study was to evaluate the relative impact of increased afterload on LV myocardial deformation indices in chronic aortic constriction, with regard to hypertrophy, myocardial fibrosis, and mitochondrial function, and to differentiate acute versus chronic afterload effect.
Young pigs underwent aortic banding (n = 11) or sham (n = 7) operations. Nineteen weeks later, LV morphology and systolic function, including myocardial deformation, were assessed by echocardiography before and after banding release or acute aortic constriction (in the sham group). After the animals were euthanized, mitochondrial function and LV interstitial fibrosis were assessed.
The chronic banding group (n = 8) presented with significant LV hypertrophy compared with the sham group (n = 7), and longitudinal strain (LS) was significantly altered (16.9 ± 0.7% vs 20.3 ± 0.7%, P = .001) while circumferential, radial strain, and ejection fraction were not. LS abnormalities were situated mostly on the basal and mid segments and on the septal wall. There was also significantly more myocardial fibrosis in the chronic banding group compared with the sham group, while mitochondrial function was preserved. The relative contributions of hypertrophic and fibrotic remodeling and of afterload to alter global LS were 62%, and 38%, respectively. Acute aortic banding also significantly altered LS. The ratio of LS to septal wall thickness enabled differentiation between chronic and acute afterload increase (1.9 ± 0.2 in the chronic group vs 2.9 ± 0.3 in the acute group, P = .001).
LS is susceptible to both hypertrophic and fibrotic remodeling and afterload increase, particularly on the basal and mid LV segments of the septum. The ratio of LS to septal wall thickness enables differentiation of acute from chronic afterload LS alteration.
左心室（LV）后负荷可能与心肌收缩力降低有关。本研究的目的是评估后负荷增加对慢性主动脉缩窄时左心室心肌变形指标的相对影响，涉及心肌肥厚、心肌纤维化和线粒体功能，并区分急性与慢性后负荷效应。
对幼猪进行主动脉缩窄手术（n = 11）或假手术（n = 7）。19周后，在缩窄解除或急性主动脉缩窄（假手术组）前后，通过超声心动图评估左心室形态和收缩功能，包括心肌变形。动物安乐死后，评估线粒体功能和左心室间质纤维化。
与假手术组（n = 7）相比，慢性缩窄组（n = 8）出现显著的左心室肥厚，纵向应变（LS）显著改变（16.9±0.7%对20.3±0.7%，P = 0.001），而圆周应变、径向应变和射血分数未改变。LS异常主要位于基底段和中间段以及室间隔壁。与假手术组相比，慢性缩窄组的心肌纤维化也显著更多，而线粒体功能得以保留。肥厚性和纤维化重塑以及后负荷对改变整体LS的相对贡献分别为62%和38%。急性主动脉缩窄也显著改变了LS。LS与室间隔壁厚度的比值能够区分慢性和急性后负荷增加（慢性组为1.9±0.2，急性组为2.9±0.3，P = 0.001）。
LS易受肥厚性和纤维化重塑以及后负荷增加影响，尤其是在室间隔的左心室基底段和中间段。LS与室间隔壁厚度的比值能够区分急性与慢性后负荷引起的LS改变。
