Original Article
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Radiol. Dec 28, 2013; 5(12): 472-483
Published online Dec 28, 2013. doi: 10.4329/wjr.v5.i12.472
Magnetic resonance imaging characterization of circumferential and longitudinal strain under various coronary interventions in swine
Mohammed SA Suhail, Mark W Wilson, Steven W Hetts, Maythem Saeed
Mohammed SA Suhail, Mark W Wilson, Steven W Hetts, Maythem Saeed, Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, CA 94107-5705, United States
Mohammed SA Suhail, School of Medicine, University of California San Diego, CA 94107-5705, United States
Author contributions: Suhail MSA achieved and analyzed the images, prepared the figures and drafted the manuscript; Wilson MW and Hetts SW provided vital advices and were also involved in the editing; Saeed M designed the study, performed the experiments and wrote the final version of the manuscript.
Correspondence to: Maythem Saeed, PhD, Professor, Department of Radiology and Biomedical Imaging, School of Medicine, University of California San Francisco, 185 Berry Street, Suite 350, Campus Box 0946, San Francisco, CA 94107-5705, United States. msaeed@ucsf.edu
Telephone: +1-415-5146221 Fax: +1-415-3539423
Received: July 26, 2013
Revised: October 18, 2013
Accepted: December 9, 2013
Published online: December 28, 2013

AIM: To compare the acute changes in circumferential and longitudinal strain after exposing a coronary artery to various interventions in swine.

METHODS: Percutaneous balloon angioplasty catheter was guided to location aid device (LAD) under X-ray fluoroscopy to create different patterns of ischemic insults. Pigs (n = 32) were equally divided into 4 groups: controls, 90 min LAD occlusion/reperfusion, LAD microembolization, and combined LAD occlusion/microembolization/reperfusion. Three days after interventions, cine, tagged and viability magnetic resonance imaging (MRI) were acquired to measure and compare left and right circumferential strain, longitudinal strain and myocardial viability, respectively. Measurements were obtained using HARP and semi-automated threshold method and statistically analyzed using unpaired t-test. Myocardial and vascular damage was characterized microscopically.

RESULTS: Coronary microemboli caused greater impairment in l left ventricular (LV) circumferential strain and dyssynchrony than LAD occlusion/reperfusion despite the significant difference in the extent of myocardial damage. Microemboli also caused significant decrease in peak systolic strain rate of remote myocardium and LV dyssynchrony. Cine MRI demonstrated the interaction between LV and right ventricular (RV) at 3 d after interventions. Compensatory increase in RV free wall longitudinal strain was seen in response to all interventions. Viability MRI, histochemical staining and microscopy revealed different patterns of myocardial damage and microvascular obstruction.

CONCLUSION: Cine MRI revealed subtle changes in LV strain caused by various ischemic insults. It also demonstrated the interaction between the right and left ventricles after coronary interventions. Coronary microemboli with and without acute myocardial infarction (AMI) cause complex myocardial injury and ventricular dysfunction that is not replicated in solely AMI.

Keywords: Magnetic resonance imaging, Percutaneous coronary interventions, Acute myocardial infarct, Microembolization, Myocardial strain

Core tip: Cine and tagging magnetic resonance imaging showed that segments in pre-existing acute myocardial superimposed with microemboli have the most severe impairment in both longitudinal and circumferential strain, while segments subjected to solely microembolization or location aid device (LAD) occlusion/reperfusion showed only circumferential impairment. The interaction between right and left ventricles after LAD interventions is clearly demonstrated by the increase in right ventricular (RV) free wall strain, suggesting that both left ventricular and RV need assessment in ischemic heart disease.