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      Critical Single Proximal Left Arterial Descending Coronary Artery Stenosis to Mimic Chronic Myocardial Ischemia: A New Model Induced by Minimal Invasive Technology

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          Abstract

          Background/Aims: The present report examines a new pig model for progressive induction of high-grade stenosis, for the study of chronic myocardial ischemia and the dynamics of collateral vessel growth. Methods: Thirty-nine Landrace pigs were instrumented with a novel experimental stent (GVD stent) in the left anterior descending coronary artery. Eight animals underwent transthoracic echocardiography at rest and under low-dose dobutamine. Seven animals were examined by nuclear PET and SPECT analysis. Epi-, mid- and endocardial fibrosis and the numbers of arterial vessels were examined by histology. Results: Functional analysis showed a significant decrease in global left ventricular ejection fraction (24.5 ± 1.6%) 3 weeks after implantation. There was a trend to increased left ventricular ejection fraction after low-dose dobutamine stress (36.0 ± 6.6%) and a significant improvement of the impaired regional anterior wall motion. PET and SPECT imaging documented chronic hibernation. Myocardial fibrosis increased significantly in the ischemic area with a gradient from epi- to endocardial. The number of arterial vessels in the ischemic area increased and coronary angiography showed abundant collateral vessels of Rentrop class 1. Conclusion: The presented experimental model mimics the clinical situation of chronic myocardial ischemia secondary to 1-vessel coronary disease.

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          Most cited references 14

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          Picrosirius staining plus polarization microscopy, a specific method for collagen detection in tissue sections

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            Changes in collateral channel filling immediately after controlled coronary artery occlusion by an angioplasty balloon in human subjects.

            Transluminal coronary angioplasty can serve as a model for controlled coronary artery occlusion and reperfusion which enables assessment of short-term changes in collateral vessel filling in patients with severe atherosclerotic coronary artery disease. In 16 patients with isolated left anterior descending or right coronary artery disease (greater than or equal to 75% stenosis) and normal left ventricular function, collateral filling to the artery being dilated was visualized by contrast injection into the contralateral artery using a second arterial catheter. During balloon inflation, contralateral dye injection was performed as soon as the patient developed angina or ST-T changes or at 90 seconds in those patients without symptoms or signs of ischemia. Grades of collateral filling from the contralateral vessel were: 0 = none; 1 = filling of side branches of the artery to be dilated via collateral channels without visualization of the epicardial segment; 2 = partial filling of the epicardial segment via collateral channels; 3 = complete filling of the epicardial segment of the artery being dilated via collateral channels. At baseline angiography, nine patients had grade 0 collateral filling, seven had grade 1 and none had grade 2 or 3. During coronary occlusion by balloon inflation, collateral filling improved by one grade in eight patients, two grades in five patients, three grades in two patients and remained the same in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)
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              TIMI Frame Count : A Quantitative Method of Assessing Coronary Artery Flow

              Background Although the Thrombolysis in Myocardial Infarction (TIMI) flow grade is a valuable and widely used qualitative measure in angiographic trials, it is limited by its subjective and categorical nature. Methods and Results In normal patients and patients with acute myocardial infarction (MI) (TIMI 4), the number of cineframes needed for dye to reach standardized distal landmarks was counted to objectively assess an index of coronary blood flow as a continuous variable. The TIMI frame-counting method was reproducible (mean absolute difference between two injections, 4.7±3.9 frames, n=85). In 78 consecutive normal arteries, the left anterior descending coronary artery (LAD) TIMI frame count (36.2±2.6 frames) was 1.7 times longer than the mean of the right coronary artery (20.4±3.0) and circumflex counts (22.2±4.1, P <.001 for either versus LAD). Therefore, the longer LAD frame counts were corrected by dividing by 1.7 to derive the corrected TIMI frame count (CTFC). The mean CTFC in culprit arteries 90 minutes after thrombolytic administration followed a continuous unimodal distribution (there were not subpopulations of slow and fast flow) with a mean value of 39.2±20.0 frames, which improved to 31.7±12.9 frames by 18 to 36 hours ( P <.001). No correlation existed between improvements in CTFCs and changes in minimum lumen diameter ( r =−.05, P =.59). The mean 90-minute CTFC among nonculprit arteries (25.5±9.8) was significantly higher (flow was slower) compared with arteries with normal flow in the absence of acute MI (21.0±3.1, P <.001) but improved to that of normal arteries by 1 day after thrombolysis (21.7±7.1, P =NS). Conclusions The CTFC is a simple, reproducible, objective, and quantitative index of coronary flow that allows standardization of TIMI flow grades and facilitates comparisons of angiographic end points between trials. Disordered resistance vessel function may account in part for reductions in flow in the early hours after thrombolysis.
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                Author and article information

                Journal
                JVR
                J Vasc Res
                10.1159/issn.1018-1172
                Journal of Vascular Research
                S. Karger AG
                1018-1172
                1423-0135
                2009
                June 2009
                11 December 2008
                : 46
                : 4
                : 290-298
                Affiliations
                aSecond Medical Clinic, bInstitute for Neurosurgical Pathophysiology and cClinic for Nuclear Medicine, Johannes Gutenberg University Mainz, and dThoracic and Cardiovascular Surgery, University Hospitals Saarland, Homburg/Saar, Germany; eInstitut Universitaire de Pathologie, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
                Article
                181545 J Vasc Res 2009;46:290–298
                10.1159/000181545
                19077390
                356dc3d9-d51e-4992-a8e2-52fd99e4cfb6
                © 2008 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 8, References: 32, Pages: 9
                Categories
                Methods in Vascular Biology

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