Badri Karthikeyan1, Swati D Sonkawade1, Saraswati Pokharel2, Marilena Preda3, Ferdinand Schweser3, Robert Zivadinov3, Minhyung Kim4, Umesh C Sharma5. 1. Department of Medicine, Division of Cardiology, Jacob's School of Medicine and Biomedical Sciences, Buffalo, NY, United States of America. 2. Department of Pathology and Laboratory Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States of America. 3. Center for Biomedical Imaging at the Clinical and Translational Science Institute, University at Buffalo, Buffalo, NY, United States of America. 4. Department of Surgical Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States of America. 5. Department of Medicine, Division of Cardiology, Jacob's School of Medicine and Biomedical Sciences, Buffalo, NY, United States of America. Electronic address: sharmau@buffalo.edu.
Abstract
PURPOSE: The conventional volumetric approaches of measuring cardiac function are load-dependent, and are not able to discriminate functional changes in the infarct, transition and remote myocardium. We examined phase-dependent regional mechanical changes in the infarct, transition and remote regions after acute myocardial infarction (MI) in a preclinical mouse model using cardiovascular magnetic resonance imaging (CMR). METHODS: We induced acute MI in six mice with left anterior descending coronary artery ligation. We then examined cardiac (infarct, transition and remote-zone) morphology and function utilizing 9.4 T high field CMR before and 2 weeks after the induction of acute MI. Myocardial scar tissue was evaluated by using CMR with late gadolinium enhancement (LGE). After determining global function through volumetric analysis, regional wall motion was evaluated by measuring wall thickening and radial velocities. Strain rate imaging was performed to assess circumferential contraction and relaxation at the myocardium, endocardium, and epicardium. RESULTS: There was abnormal LGE in the anterior walls after acute MI suggesting a successful MI procedure. The transition zone consisted of a mixed signal intensity, while the remote zone contained viable myocardium. As expected, the infarct zone had demonstrated severely decreased myocardial velocities and strain rates, suggesting reduced contraction and relaxation function. Compared to pre-infarct baseline, systolic and diastolic velocities (vS and vD) were significantly reduced at the transition zone (vS: -1.86 ± 0.16 cm/s vs -0.68 ± 0.13 cm/s, P < 0.001; vD: 1.86 ± 0.17 cm/s vs 0.53 ± 0.06 cm/s, P < 0.001) and remote zone (vS: -1.86 ± 0.16 cm/s vs -0.65 ± 0.12 cm/s, P < 0.001; vD: 1.86 ± 0.16 cm/s vs 0.51 ± 0.04 cm/s, P < 0.001). Myocardial peak systolic and diastolic strain rates (SRS and SRD) were significantly lower in the transition zone (SRS: -4.2 ± 0.3 s-1 vs -1.3 ± 0.2 s-1, P < 0.001; SRD: 3.9 ± 0.3 s-1 vs 1.3 ± 0.2 s-1, P < 0.001) and remote zone (SRS: -3.8 ± 0.3 s-1 vs -1.4 ± 0.3 s-1, P < 0.001; SRD: 3.5 ± 0.2 s-1 vs 1.5 ± 0.4 s-1, P = 0.006). Endocardial and epicardial SRS and SRD were similarly reduced in the transition and remote zones compared to baseline. CONCLUSIONS: This study, for the first time, utilized state-of-the art high-field CMR algorithms in a preclinical mouse model for a comprehensive and controlled evaluation of the regional mechanical changes in the transition and remote zones, after acute MI. Our data demonstrate that CMR can quantitatively monitor dynamic post-MI remodeling in the transition and remote zones, thereby serving as a gold standard tool for therapeutic surveillance.
PURPOSE: The conventional volumetric approaches of measuring cardiac function are load-dependent, and are not able to discriminate functional changes in the infarct, transition and remote myocardium. We examined phase-dependent regional mechanical changes in the infarct, transition and remote regions after acute myocardial infarction (MI) in a preclinical mouse model using cardiovascular magnetic resonance imaging (CMR). METHODS: We induced acute MI in six mice with left anterior descending coronary artery ligation. We then examined cardiac (infarct, transition and remote-zone) morphology and function utilizing 9.4 T high field CMR before and 2 weeks after the induction of acute MI. Myocardial scar tissue was evaluated by using CMR with late gadolinium enhancement (LGE). After determining global function through volumetric analysis, regional wall motion was evaluated by measuring wall thickening and radial velocities. Strain rate imaging was performed to assess circumferential contraction and relaxation at the myocardium, endocardium, and epicardium. RESULTS: There was abnormal LGE in the anterior walls after acute MI suggesting a successful MI procedure. The transition zone consisted of a mixed signal intensity, while the remote zone contained viable myocardium. As expected, the infarct zone had demonstrated severely decreased myocardial velocities and strain rates, suggesting reduced contraction and relaxation function. Compared to pre-infarct baseline, systolic and diastolic velocities (vS and vD) were significantly reduced at the transition zone (vS: -1.86 ± 0.16 cm/s vs -0.68 ± 0.13 cm/s, P < 0.001; vD: 1.86 ± 0.17 cm/s vs 0.53 ± 0.06 cm/s, P < 0.001) and remote zone (vS: -1.86 ± 0.16 cm/s vs -0.65 ± 0.12 cm/s, P < 0.001; vD: 1.86 ± 0.16 cm/s vs 0.51 ± 0.04 cm/s, P < 0.001). Myocardial peak systolic and diastolic strain rates (SRS and SRD) were significantly lower in the transition zone (SRS: -4.2 ± 0.3 s-1 vs -1.3 ± 0.2 s-1, P < 0.001; SRD: 3.9 ± 0.3 s-1 vs 1.3 ± 0.2 s-1, P < 0.001) and remote zone (SRS: -3.8 ± 0.3 s-1 vs -1.4 ± 0.3 s-1, P < 0.001; SRD: 3.5 ± 0.2 s-1 vs 1.5 ± 0.4 s-1, P = 0.006). Endocardial and epicardial SRS and SRD were similarly reduced in the transition and remote zones compared to baseline. CONCLUSIONS: This study, for the first time, utilized state-of-the art high-field CMR algorithms in a preclinical mouse model for a comprehensive and controlled evaluation of the regional mechanical changes in the transition and remote zones, after acute MI. Our data demonstrate that CMR can quantitatively monitor dynamic post-MI remodeling in the transition and remote zones, thereby serving as a gold standard tool for therapeutic surveillance.
Authors: Philippe Gabriel Steg; Omar H Dabbous; Laurent J Feldman; Alain Cohen-Solal; Marie-Claude Aumont; José López-Sendón; Andrzej Budaj; Robert J Goldberg; Werner Klein; Frederick A Anderson Journal: Circulation Date: 2004-01-26 Impact factor: 29.690