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Wahadat AR, Tanis W, Swart LE, Scholtens A, Krestin GP, van Mieghem NMDA, Schurink CAM, van der Spoel TIG, van den Brink FS, Vossenberg T, Slart RHJA, Glaudemans AWJM, Roos-Hesselink JW, Budde RPJ. Added value of 18F-FDG-PET/CT and cardiac CTA in suspected transcatheter aortic valve endocarditis. J Nucl Cardiol 2021; 28:2072-2082. [PMID: 31792918 PMCID: PMC8648682 DOI: 10.1007/s12350-019-01963-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 11/05/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUNDS Transcatheter-implanted aortic valve infective endocarditis (TAVI-IE) is difficult to diagnose when relying on the Duke Criteria. Our aim was to assess the additional diagnostic value of 18F-fluorodeoxyglucose (18F-FDG) positron emission/computed tomography (PET/CT) and cardiac computed tomography angiography (CTA) in suspected TAVI-IE. METHODS A multicenter retrospective analysis was performed in all patients who underwent 18F-FDG-PET/CT and/or CTA with suspected TAVI-IE. Patients were first classified with Duke Criteria and after adding 18F-FDG-PET/CT and CTA, they were classified with European Society of Cardiology (ESC) criteria. The final diagnosis was determined by our Endocarditis Team based on ESC guideline recommendations. RESULTS Thirty patients with suspected TAVI-IE were included. 18F-FDG-PET/CT was performed in all patients and Cardiac CTA in 14/30. Using the Modified Duke Criteria, patients were classified as 3% rejected (1/30), 73% possible (22/30), and 23% definite (7/30) TAVI-IE. Adding 18F-FDG-PET/CT and CTA supported the reclassification of 10 of the 22 possible cases as "definite TAVI-IE" (5/22) or "rejected TAVI-IE" (5/22). This changed the final diagnosis to 20% rejected (6/30), 40% possible (12/30), and 40% definite (12/30) TAVI-IE. CONCLUSIONS Addition of 18F-FDG-PET/CT and/or CTA changed the final diagnosis in 33% of patients and proved to be a valuable diagnostic tool in patients with suspected TAVI-IE.
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Affiliation(s)
- Ali R Wahadat
- Department of Radiology and Nuclear Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands.
- Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands.
- Departments Radiology, Erasmus MC, NA-2618, Dr. Molewaterplein 40, 3015GD, Rotterdam, The Netherlands.
| | - Wilco Tanis
- Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands
| | - Laurens E Swart
- Department of Radiology and Nuclear Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Asbjørn Scholtens
- Department of Nuclear Medicine, Meander Medical Center, Amersfoort, The Netherlands
| | - Gabriel P Krestin
- Department of Radiology and Nuclear Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Carolina A M Schurink
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Tycho I G van der Spoel
- Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands
- Department of Cardiology, Utrecht Medical Center, Utrecht, The Netherlands
| | - Floris S van den Brink
- Department of Cardiology, St. Antonius Hospital, Nieuwegein, The Netherlands
- Department of Cardiology, Medical Center Leeuwarden, Leeuwarden, The Netherlands
| | - Tessel Vossenberg
- Department of Cardiology, Medical Center Leeuwarden, Leeuwarden, The Netherlands
| | - Riemer H J A Slart
- Department of Nuclear Medicine & Molecular Imaging, Medical Imaging Center, University Medical Center of Groningen, Groningen, The Netherlands
| | - Andor W J M Glaudemans
- Department of Nuclear Medicine & Molecular Imaging, Medical Imaging Center, University Medical Center of Groningen, Groningen, The Netherlands
| | | | - Ricardo P J Budde
- Department of Radiology and Nuclear Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
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Deddens JC, Vrijsen KR, Colijn JM, Oerlemans MI, Metz CHG, van der Vlist EJ, Nolte-'t Hoen ENM, den Ouden K, Jansen Of Lorkeers SJ, van der Spoel TIG, Koudstaal S, Arkesteijn GJ, Wauben MHM, van Laake LW, Doevendans PA, Chamuleau SAJ, Sluijter JPG. Circulating Extracellular Vesicles Contain miRNAs and are Released as Early Biomarkers for Cardiac Injury. J Cardiovasc Transl Res 2016; 9:291-301. [PMID: 27383837 PMCID: PMC4990609 DOI: 10.1007/s12265-016-9705-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/21/2016] [Indexed: 11/25/2022]
Abstract
Plasma-circulating microRNAs have been implicated as novel early biomarkers for myocardial infarction (MI) due to their high specificity for cardiac injury. For swift clinical translation of this potential biomarker, it is important to understand their temporal and spatial characteristics upon MI. Therefore, we studied the temporal release, potential source, and transportation of circulating miRNAs in different models of ischemia reperfusion (I/R) injury. We demonstrated that extracellular vesicles are released from the ischemic myocardium upon I/R injury. Moreover, we provided evidence that cardiac and muscle-specific miRNAs are transported by extracellular vesicles and are rapidly detectable in plasma. Since these vesicles are enriched for the released miRNAs and their detection precedes traditional damage markers, they hold great potential as specific early biomarkers for MI.
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Affiliation(s)
- Janine C Deddens
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
- Netherlands Heart Institute (ICIN), Utrecht, The Netherlands
| | - Krijn R Vrijsen
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Johanna M Colijn
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Martinus I Oerlemans
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Corina H G Metz
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
- UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Els J van der Vlist
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Esther N M Nolte-'t Hoen
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Krista den Ouden
- UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | - Stefan Koudstaal
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ger J Arkesteijn
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Marca H M Wauben
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Linda W van Laake
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
- UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Pieter A Doevendans
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
- UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht, The Netherlands
- Netherlands Heart Institute (ICIN), Utrecht, The Netherlands
| | - Steven A J Chamuleau
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
- UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht, The Netherlands
- Netherlands Heart Institute (ICIN), Utrecht, The Netherlands
| | - Joost P G Sluijter
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
- UMC Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht, The Netherlands.
- Netherlands Heart Institute (ICIN), Utrecht, The Netherlands.
- Department of Cardiology, Experimental Cardiology Laboratory, University Medical Center Utrecht, Heidelberglaan 100, PO Box 85500, 3508 GA, Utrecht, The Netherlands.
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van Slochteren FJ, van der Spoel TIG, Hansen HHG, Bovendeerd PHM, Doevendans PA, Sluijter JPG, Chamuleau SAJ, de Korte CL. Layer-specific radiofrequency ultrasound-based strain analysis in a porcine model of ischemic cardiomyopathy validated by a geometric model. Ultrasound Med Biol 2014; 40:378-388. [PMID: 24315396 DOI: 10.1016/j.ultrasmedbio.2013.09.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 09/05/2013] [Accepted: 09/26/2013] [Indexed: 06/02/2023]
Abstract
Local layer-specific myocardial deformation after myocardial infarction (MI) has not been studied extensively although the sub-endocardium is more vulnerable to ischemia and interstitial fibrosis deposition. Radiofrequency (RF) ultrasound-based analysis could provide superior layer-specific radial strain estimation compared with clinically available deformation imaging techniques. In this study, we used RF-based myocardial deformation measurements to investigate layer-specific differences between healthy and damaged myocardium in a porcine model of chronic MI. RF data were acquired epicardially in healthy (n = 21) and infarcted (n = 5) regions of a porcine chronic MI model 12 wk post-MI. Radial and longitudinal strains were estimated in the sub-endocardial, mid-wall and sub-epicardial layers of the left ventricle. Collagen content was quantified in three layers of healthy and infarcted regions in five pigs. An analytical geometric model of the left ventricle was used to theoretically underpin the radial deformation estimated in different myocardial layers. Means ± standard errors of the peak radial and longitudinal strain estimates of the sub-endocardial, mid-wall and sub-epicardial layers of the healthy and infarcted tissue were: 82.7 ± 5.2% versus 39.9 ± 10.8% (p = 0.002), 63.6 ± 3.3% versus 38.8 ± 7.7% (p = 0.004) and 34.3 ± 3.0% versus 35.1 ± 5.2% (p = 0.9), respectively. The radial strain gradient between the sub-endocardium and the sub-epicardium had decreased 12 wk after MI, and histologic examination revealed the greatest increases in collagen in the sub-endocardial and mid-wall layers. Comparable normal peak radial strain values were found by geometric modeling when input values were derived from the in vivo measurements and literature. In conclusion, the estimated strain values are realistic and indicate that sub-endocardial radial strain in healthy tissue can amount to 80%. This high value can be explained by the cardiac geometry, as was illustrated by geometric modeling. After MI, strain values were decreased and collagen content was increased in the sub-endocardial and mid-wall layers. Layer-specific peak radial strain can be assessed by RF strain estimation and clearly differs between healthy and infarcted tissue. Although the relationship between tissue stiffness and tissue strain is not strictly local, this novel technique provides a valuable way to assess layer-specific regional cardiac function in a variety of myocardial diseases.
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Affiliation(s)
| | | | - Hendrik H G Hansen
- Medical Ultrasound Imaging Center, Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Peter H M Bovendeerd
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Pieter A Doevendans
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Joost P G Sluijter
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Steven A J Chamuleau
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Chris L de Korte
- Medical Ultrasound Imaging Center, Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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van der Spoel TIG, Vrijsen KR, Koudstaal S, Sluijter JPG, Nijsen JFW, de Jong HW, Hoefer IE, Cramer MJM, Doevendans PA, van Belle E, Chamuleau SAJ. Transendocardial cell injection is not superior to intracoronary infusion in a porcine model of ischaemic cardiomyopathy: a study on delivery efficiency. J Cell Mol Med 2014; 16:2768-76. [PMID: 22697212 PMCID: PMC4118245 DOI: 10.1111/j.1582-4934.2012.01594.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Stem cell therapy is a new strategy for chronic ischaemic heart disease in patients. However, no consensus exists on the most optimal delivery strategy. This randomized study was designed to assess cell delivery efficiency of three clinically relevant strategies: intracoronary (IC) and transendocardial (TE) using electromechanical mapping guidance (NOGA) compared to surgical delivery in a chronic pig model of ischaemic cardiomyopathy. Twenty-four animals underwent delivery of 10(7) autologous Indium-oxine-labelled bone marrow-derived mesenchymal stem cells (MSC) 4 weeks after infarction and were randomized to one of three groups (n = 8 each group): IC, TE or surgical delivery (reference group). Primary endpoint was defined as percentage (%) of injected dose per organ and assessed by in vivo gamma-emission counting. In addition, troponin and coronary flow were assessed before and after MSC injection. Blinded endpoint analysis showed no significant difference in efficiency after surgical (16 ± 4%), IC (11 ± 1%) and TE (11 ± 3%) (P = 0.52) injections. IC showed less variability in efficiency compared with TE and surgical injection. Overall, TE injection showed less distribution of MSC to visceral organs compared with other modalities. Troponin rise and IC flow did not differ between the percutaneous groups. This randomized study showed no significant difference in cell delivery efficiency to the myocardium in a clinically relevant ischaemic large animal model between IC and TE delivery. In addition, no differences in safety profile were observed. These results are important in view of the choice of percutaneous cell delivery modality in future clinical stem cell trials.
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Affiliation(s)
- Tycho I G van der Spoel
- Division Heart and Lungs, Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
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Koudstaal S, Jansen Of Lorkeers SJ, van Slochteren FJ, van der Spoel TIG, van de Hoef TP, Sluijter JP, Siebes M, Doevendans PA, Piek JJ, Chamuleau SAJ. Assessment of coronary microvascular resistance in the chronic infarcted pig heart. J Cell Mol Med 2013; 17:1128-35. [PMID: 23910946 PMCID: PMC4118172 DOI: 10.1111/jcmm.12089] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 05/20/2013] [Indexed: 12/24/2022] Open
Abstract
Pre-clinical studies aimed at treating ischemic heart disease (i.e. stem cell- and growth factor therapy) often consider restoration of the impaired microvascular circulation as an important treatment goal. However, serial in vivo measurement hereof is often lacking. The purpose of this study was to evaluate the applicability of intracoronary pressure and flow velocity as a measure of microvascular resistance in a large animal model of chronic myocardial infarction (MI). Myocardial infarction was induced in Dalland Landrace pigs (n = 13; 68.9 ± 4.1 kg) by a 75-min. balloon occlusion of the left circumflex artery (LCX). Intracoronary pressure and flow velocity parameters were measured simultaneously at rest and during adenosine-induced hyperemia, using the Combowire (Volcano) before and 4 weeks after MI. Various pressure- and/or flow-derived indices were evaluated. Hyperemic microvascular resistance (HMR) was significantly increased by 28% in the infarct-related artery, based on a significantly decreased peak average peak flow velocity (pAPV) by 20% at 4 weeks post-MI (P = 0.03). Capillary density in the infarct zone was decreased compared to the remote area (658 ± 207/mm2versus 1650 ± 304/mm2, P = 0.017). In addition, arterioles in the infarct zone showed excessive thickening of the alpha smooth muscle actin (αSMA) positive cell layer compared to the remote area (33.55 ± 4.25 μm versus 14.64 ± 1.39 μm, P = 0.002). Intracoronary measurement of HMR successfully detected increased microvascular resistance that might be caused by the loss of capillaries and arteriolar remodelling in the chronic infarcted pig heart. Thus, HMR may serve as a novel outcome measure in pre-clinical studies for serial assessment of microvascular circulation.
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Affiliation(s)
- Stefan Koudstaal
- Department of Cardiology, Division Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
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Houtgraaf JH, de Jong R, Kazemi K, de Groot D, van der Spoel TIG, Arslan F, Hoefer I, Pasterkamp G, Itescu S, Zijlstra F, Geleijnse ML, Serruys PW, Duckers HJ. Intracoronary infusion of allogeneic mesenchymal precursor cells directly after experimental acute myocardial infarction reduces infarct size, abrogates adverse remodeling, and improves cardiac function. Circ Res 2013; 113:153-66. [PMID: 23658436 DOI: 10.1161/circresaha.112.300730] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
RATIONALE Mesenchymal precursor cells (MPCs) are a specific Stro-3+ subpopulation of mesenchymal stem cells isolated from bone marrow. MPCs exert extensive cardioprotective effects, and are considered to be immune privileged. OBJECTIVE This study assessed the safety, feasibility, and efficacy of intracoronary delivery of allogeneic MPCs directly after acute myocardial infarction in sheep. METHODS AND RESULTS Initially, intracoronary delivery conditions were optimized in 20 sheep. These conditions were applied in a randomized study of 68 sheep with an anterior acute myocardial infarction. Coronary flow was monitored during MPC infusion, and cardiac function was assessed using invasive hemodynamics and echocardiography at baseline and during 8 weeks follow-up. Coronary flow remained within thrombolysis in myocardial infarction III definitions in all sheep during MPC infusion. Global left ventricular ejection fraction as measured by pressure-volume loop analysis deteriorated in controls to 40.7±2.6% after 8 weeks. In contrast, MPC treatment improved cardiac function to 52.8±0.7%. Echocardiography revealed significant improvement of both global and regional cardiac functions. Infarct size decreased by 40% in treated sheep, whereas infarct and border zone thickness were enhanced. Left ventricular adverse remodeling was abrogated by MPC therapy, resulting in a marked reduction of left ventricular volumes. Blood vessel density increased by >50% in the infarct and border areas. Compensatory cardiomyocyte hypertrophy was reduced in border and remote segments, accompanied by reduced collagen deposition and apoptosis. No microinfarctions in remote myocardial segments or histological abnormalities in unrelated organs were found. CONCLUSIONS Intracoronary infusion of allogeneic MPCs is safe, feasible, and markedly effective in a large animal model of acute myocardial infarction.
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Affiliation(s)
- Jaco H Houtgraaf
- Molecular Cardiology Laboratory, Thoraxcenter, Erasmus University Medical Center Rotterdam, The Netherlands
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Gründeman PF, van der Spoel TIG, Steendijk P, van Slochteren F, Cramer MJM, Doevendans PA, Pasterkamp G. Surgical left ventricular radius enlargement by patch insertion on the beating heart: a new experimental aneurysm model. Interact Cardiovasc Thorac Surg 2012; 15:10-3. [PMID: 22523129 DOI: 10.1093/icvts/ivr148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We presented a novel experimental aneurysm model for studies in left ventricular (LV) reconstruction techniques and assessed LV function. In eight pigs, the LV radius and geometry were enlarged surgically on the beating heart by inserting an aortic allograft construct. Haemodynamics and LV dimensions were assessed by echocardiography at baseline and under dobutamine stress. Surgery was successfully performed without lethal blood loss or arrhythmias. LV end-diastolic and end-systolic short-axis areas increased from 13.0 ± 1.7 to 17.0 ± 4.3 cm(2) (P = 0.001) and from 4.0 ± 0.9 to 13.0 ± 2.6 cm(2) (P = 0.001), respectively. Stroke volume decreased from 56 ± 11 to 33 ± 16 ml (P = 0.001). Incremental dobutamine infusion concurred with a biphasic response on fractional area shortening. Mitral valve insufficiency ranging from grades 2 to 4 was observed. In the pig, a novel, reproducible aneurysm model for acute cardiac dysfunction was created on the beating heart. Innovative (surgical) strategies for (staged) reconfiguration of the ventricle, e.g. adjustable Dor procedures and stepwise volume restraining cardiac support devices, can be tested for efficacy using this acute model.
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Affiliation(s)
- Paul F Gründeman
- Experimental Cardiology Laboratory, Division Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands.
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Ashikaga H, van der Spoel TIG, Coppola BA, Omens JH. Transmural myocardial mechanics during isovolumic contraction. JACC Cardiovasc Imaging 2009; 2:202-11. [PMID: 19356557 DOI: 10.1016/j.jcmg.2008.11.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 10/20/2008] [Accepted: 11/11/2008] [Indexed: 11/30/2022]
Abstract
OBJECTIVES We sought to resolve the 3-dimensional transmural heterogeneity in myocardial mechanics observed during the isovolumic contraction (IC) phase. BACKGROUND Although myocardial deformation during IC is expected to be little, recent tissue Doppler imaging studies suggest dynamic myocardial motions during this phase with biphasic longitudinal tissue velocities in left ventricular (LV) long-axis views. A unifying understanding of myocardial mechanics that would account for these dynamic aspects of IC is lacking. METHODS We determined the time course of 3-dimensional finite strains in the anterior LV of 14 adult mongrel dogs in vivo during IC and ejection with biplane cineradiography of implanted transmural markers. Transmural fiber orientations were histologically measured in the heart tissue postmortem. The strain time course was determined in the subepicardial, midwall, and subendocardial layers referenced to the end-diastolic configuration. RESULTS During IC, there was circumferential stretch in the subepicardial layer, whereas circumferential shortening was observed in the midwall and the subendocardial layer. There was significant longitudinal shortening and wall thickening across the wall. Although longitudinal tissue velocity showed a biphasic profile; tissue deformation in the longitudinal as well as other directions was almost linear during IC. Subendocardial fibers shortened, whereas subepicardial fibers lengthened. During ejection, all strain components showed a significant change over time that was greater in magnitude than that of IC. Significant transmural gradient was observed in all normal strains. CONCLUSIONS IC is a dynamic phase characterized by deformation in circumferential, longitudinal, and radial directions. Tissue mechanics during IC, including fiber shortening, appear uninterrupted by rapid longitudinal motion created by mitral valve closure. This study is the first to report layer-dependent deformation of circumferential strain, which results from layer-dependent deformation of myofibers during IC. Complex myofiber mechanics provide the mechanism of brief clockwise LV rotation (untwisting) and significant wall thickening during IC within the isovolumic constraint.
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Affiliation(s)
- Hiroshi Ashikaga
- Department of Medicine and Bioengineering, University of California, San Diego, CA, USA.
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