Patricia Reant1, Alexandre Metras2, Dominique Detaille3, Annabel Reynaud4, Philippe Diolez3, Beatrice Jaspard-Vinassa5, Raymond Roudaut6, Alexandre Ouattara7, Laurent Barandon2, Pierre Dos Santos8, Stephane Lafitte9. 1. INSERM U1045, Pessac, France; Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France; IHU Liryc, Pessac, France. Electronic address: patricia.reant@chu-bordeaux.fr. 2. Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France; INSERM U1034, Adaptation Cardiovasculaire à l'Ischémie, Pessac, France. 3. INSERM U1045, Pessac, France; IHU Liryc, Pessac, France. 4. INSERM U1034, Adaptation Cardiovasculaire à l'Ischémie, Pessac, France. 5. Université de Bordeaux, Bordeaux, France; INSERM U1034, Adaptation Cardiovasculaire à l'Ischémie, Pessac, France. 6. Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France. 7. Université de Bordeaux, Bordeaux, France; INSERM U1034, Adaptation Cardiovasculaire à l'Ischémie, Pessac, France; Department of Anesthesia and Critical Care II, CHU de Bordeaux, Bordeaux, France. 8. INSERM U1045, Pessac, France; Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France; IHU Liryc, Pessac, France. 9. Université de Bordeaux, Bordeaux, France; Cardiologic Hospital Haut-Leveque (Pessac), CHU de Bordeaux, Pessac, France; IHU Liryc, Pessac, France; INSERM U1034, Adaptation Cardiovasculaire à l'Ischémie, Pessac, France.
Abstract
BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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. Copyright Â
BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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. Copyright Â