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Ajit P Yoganathan - One of the best experts on this subject based on the ideXlab platform.

  • fluid structure interaction analysis of ruptured mitral Chordae tendineae
    Annals of Biomedical Engineering, 2017
    Co-Authors: Milan Toma, R P Cochran, Ajit P Yoganathan, Eric L Pierce, Charles H Bloodworth, Daniel R Einstein, Karyn S. Kunzelman
    Abstract:

    The Chordal structure is a part of mitral valve geometry that has been commonly neglected or simplified in computational modeling due to its complexity. However, these simplifications cannot be used when investigating the roles of individual Chordae tendineae in mitral valve closure. For the first time, advancements in imaging, computational techniques, and hardware technology make it possible to create models of the mitral valve without simplifications to its complex geometry, and to quickly run validated computer simulations that more realistically capture its function. Such simulations can then be used for a detailed analysis of Chordae-related diseases. In this work, a comprehensive model of a subject-specific mitral valve with detailed Chordal structure is used to analyze the distinct role played by individual Chordae in closure of the mitral valve leaflets. Mitral closure was simulated for 51 possible Chordal rupture points. Resultant regurgitant orifice area and strain change in the Chordae at the papillary muscle tips were then calculated to examine the role of each ruptured Chorda in the mitral valve closure. For certain subclassifications of Chordae, regurgitant orifice area was found to trend positively with ruptured Chordal diameter, and strain changes correlated negatively with regurgitant orifice area. Further advancements in clinical imaging modalities, coupled with the next generation of computational techniques will enable more physiologically realistic simulations.

  • quantitative evaluation of annuloplasty on mitral valve Chordae tendineae forces to supplement surgical planning model development
    Cardiovascular Engineering and Technology, 2014
    Co-Authors: Andrew W Siefert, Karyn S. Kunzelman, Jeanpierre Rabbah, Eric L Pierce, Ajit P Yoganathan
    Abstract:

    Computational models of the heart’s mitral valve (MV) exhibit potential for preoperative surgical planning in ischemic mitral regurgitation (IMR). However challenges exist in defining boundary conditions to accurately model the function and response of the Chordae tendineae to both IMR and surgical annuloplasty repair. Towards this goal, a ground-truth data set was generated by quantifying the isolated effects of IMR and mitral annuloplasty on leaflet coaptation, regurgitation, and tethering forces of the anterior strut and posterior intermediary Chordae tendineae. MVs were excised from ovine hearts (N = 15) and mounted in a pulsatile heart simulator which has been demonstrated to mimic the systolic MV geometry and coaptation of healthy and chronic IMR sheep. Strut and intermediary Chordae from both MV leaflets (N = 4) were instrumented with force transducers. Tested conditions included a healthy control, IMR, oversized annuloplasty, true-sized annuloplasty, and undersized mitral annuloplasty. A2-P2 leaflet coaptation length, regurgitation, and Chordal tethering were quantified and statistically compared across experimental conditions. MR was successfully simulated with significant increases in MR, tethering forces for each of the Chordae, and decrease in leaflet coaptation (p < .05). Compared to the IMR condition, increasing levels of downsized annuloplasty significantly reduced regurgitation, increased coaptation, reduced posteromedial papillary muscle strut Chordal forces, and reduced intermediary Chordal forces from the anterolateral papillary muscle (p < .05). These results provide for the first time a novel comprehensive data set for refining the ability of computational MV models to simulate IMR and varying sizes of complete rigid ring annuloplasty.

  • the material properties of the native porcine mitral valve Chordae tendineae an in vitro investigation
    Journal of Biomechanics, 2006
    Co-Authors: Jennifer Ritchie, Zhaoming He, Jorge H Jimenez, Michael S Sacks, Ajit P Yoganathan
    Abstract:

    Abstract The material properties of the mitral valve Chordae tendineae are important for the understanding of leaflet coaptation configuration and Chordal pathology. There is limited information about the mechanical properties of the Chordae during physiologic loading. Dual camera stereo photogrammetry was used to measure strains of the Chordae in vitro under physiologic loading conditions. Two high-speed, high-resolution cameras captured the movement of graphite markers attached to the central section of the Chordae. A uniaxial test simulating the same loading conditions was conducted on the same Chordae using the same markers. The maximum strain experienced during the cardiac cycle was 4.29%±3.43%. The loading rate was higher at 75.3%±48.6% strain per second than the unloading rate at −54.8%±−56.6% strain per second. The anterior lateral strut Chordae had a higher maximum strain (5.7%±3.8%) and loading rate (80.5%±51.9% strain per second) than the posterior medial strut Chordae (5.5%±2.3% strain and 68.1%±48.3% strain per second). The posterior medial strut Chordae had a higher unloading rate (−68.5%±−59.1% strain per second) than the anterior lateral strut Chordae (−44.9%±−57.2% strain per second). Although the anterior lateral and posterior medial strut Chordae have a significantly different diameter and length, they experience a similar strain, strain rate, and tension. In conclusion, a non-destructive technique was developed to measure in vitro Chordal strain in the mitral valve. This technique allows the investigation of the behavior of biological tissues under physiologic loading conditions.

  • effects of papillary muscle position on Chordal force distribution an in vitro study
    Journal of Heart Valve Disease, 2005
    Co-Authors: Jorge H Jimenez, Jennifer Ritchie, Zhaoming He, Ajit P Yoganathan, Dennis Dam Soerensen
    Abstract:

    BACKGROUND AND AIM OF THE STUDY: Mitral insufficiency, a common and morbid pathology, has been related to topological changes in the left ventricle. These changes may affect mitral leaflet coaptation by displacing the tips of the papillary muscles (PMs), subsequently changing the tension distribution on the Chordae tendineae. Therefore, further understanding of the effects of PM displacement on Chordal force distribution is required. METHODS: Six human and five porcine mitral valves were studied in a physiological left heart simulator. Cardiac output and transmitral pressure were recorded online and maintained within physiological ranges. Force transducers were placed on six Chordae tendineae to measure Chordal force distribution. Tension on individual Chordae tendineae was recorded online during the cardiac cycle. The experiment was conducted for eight different PM positions, which were constructed from 5-mm vectorial displacements from the normal PM position. RESULTS: The anterior strut chord showed significant (p <0.05) variations in peak systolic tension (PST) for those positions associated with apical motion of the PMs. The posterior intermediate chord also showed significant variations in PST for positions associated with apical displacement of the PMs, whereas posterior displacement of the PMs resulted in a reduction in tension. In contrast, both the anterior marginal and posterior marginal chords showed a relatively uniform PST for the eight different PM positions. The posterior basal and commissural chords were the most sensitive to tension variations due to PM displacement. These chords showed relatively large and significant (p <0.05) variations in PST for most of the different PM displacements. CONCLUSION: The effects of PM relocation on Chordal tension depended on Chordal type. Chords which insert closer to the annulus were more sensitive to PM displacement, whereas those further from the annulus, the marginal chords, were the least sensitive to PM displacement.

  • effects of a saddle shaped annulus on mitral valve function and Chordal force distribution an in vitro study
    Annals of Biomedical Engineering, 2003
    Co-Authors: Jorge H Jimenez, Zhaoming He, Dennis Dam Soerensen, Shengqiu He, Ajit P Yoganathan
    Abstract:

    Studies have concluded that the shape of the human mitral valve annulus is a three-dimensional saddle. The objective of this study was to investigate the effects of a saddle shaped annulus on Chordal force distribution and mitral valve function. Eleven human mitral valves were studied in a physiological left heart simulator with a variable shaped annulus (flat versus saddle). Cardiac output and transmitral pressure were analyzed to determine mitral regurgitation volume. In six experiments, force transducers were placed on six Chordae tendineae to measure Chordal force distribution. Valves were tested in normal and pathophysiologic papillary muscle positions. When comparing the flat and saddle shaped configurations, there was no significant difference in mitral regurgitation volume 11.2% ± 24.7% (p=0.17). In the saddle shaped configuration, the tension on the anterior strut chord was reduced 18.5% #x00B1 16.1% (p < 0.02), the tension on the posterior intermediate chord increased 22.3% #x00B1 17.1% (p < 0.03), and the tension of the commissural chord increased 59.0% #x00B1 32.2% (p < 0.01). Annular shape also altered the tensions on the remaining chords. Annular shape alone does not significantly affect mitral regurgitation caused by papillary muscle displacement. A saddle shaped annulus redistributes the forces on the chords by altering coaptation geometry, leading to an optimally balanced anatomic/physiologic configuration. © 2003 Biomedical Engineering Society.

Sten Lyager Nielsen - One of the best experts on this subject based on the ideXlab platform.

  • imbalanced Chordal force distribution causes acute ischemic mitral regurgitation mechanistic insights from Chordae tendineae force measurements in pigs
    The Journal of Thoracic and Cardiovascular Surgery, 2005
    Co-Authors: Sten Lyager Nielsen, Soren B Hansen, Katrine Nielsen, P K Paulsen, Michael J Hasenkam
    Abstract:

    Background Ischemic mitral regurgitation is caused by an imbalance of the entire mitral-ventricular complex. This interaction is mediated through the Chordae tendineae force distribution, which may perturb several elements of the mitral valve apparatus. Our objective was to investigate the association between the mitral valvular 3-dimensional geometric perturbations and Chordae tendineae force redistribution in a porcine model of acute ischemic mitral regurgitation. Methods In 9 pigs, acute ischemic mitral regurgitation was induced by repeated microembolization of the left circumflex coronary artery. Mitral leaflet coaptation geometry was determined by 2-dimensional echocardiography and reconstructed 3-dimensionally. Leading edge Chordal forces were measured by dedicated miniature force transducers at control and during ischemic mitral regurgitation. Results During acute ischemic mitral regurgitation, there was a decreased tension of the primary Chorda from the ischemic posterior left ventricular wall to the anterior leaflet (0.295 ± 0.063 N vs 0.336 ± 0.071 N [control]; P P Conclusions Acute ischemic mitral regurgitation due to posterior left ventricular wall ischemia was associated with focal Chordal and leaflet tethering at the nonischemic commissural portion of the mitral valve and a paradoxical decrease of the Chordal forces and relative prolapse at the ischemic site of the anterior mitral valve leaflet.

  • influence of anterior mitral leaflet second order Chordae tendineae on left ventricular systolic function
    Circulation, 2003
    Co-Authors: Sten Lyager Nielsen, Michael J Hasenkam, Ann F Bolger, Neil B Ingels, George T Daughters, Tomasz A Timek, Randall G Green, Paul Dagum, Craig D Miller
    Abstract:

    BACKGROUND: The contribution of anterior mitral leaflet second-order ("strut") Chordae tendineae to left ventricular (LV) systolic mechanics is debated; we measured the in vivo contribution of anterior Chordae tendineae (ACT) and posterior Chordae tendineae (PCT) to regional and global LV contractile function. METHODS AND RESULTS: Eight sheep had radiopaque markers implanted in the LV epicardium, partitioning the ventricle into 12 regions. Microminiature force transducers and snares were sutured to anterior leaflet "strut" Chordae originating from ACT and PCT papillary muscles. Chordal tension, marker images, and hemodynamic data were acquired before and after (CUT) severing ACT and PCT. Fractional area shrinkage and slope of the regional end-diastolic area-regional stroke work relation (r-PRSW) were computed for each LV region. CUT did not affect global LV systolic function but reduced FAS in LV segments near the PCT insertion site: equatorial posterior lateral (19+/-2% versus 16+/-2%, P<0.05), apical posterior lateral (23+/-4% versus 19+/-4%, P<0.05), and posterior medial LV segments (16+/-2% versus 13+/-2%, P<0.05). r-PRSW fell near both the ACT (equatorial anterior medial [84+/-8 versus 62+/-11 mm Hg, P<0.05] and lateral [73+/-7 versus 53+/-9 mm Hg, P<0.05]) and PCT (apical posterior medial [91+/-12 versus 67+/-17 mm Hg, P<0.05] and lateral [72+/-8 versus 59+/-9 mm Hg, P<0.05]) LV insertion sites. Maximum tension in PCT was higher than in ACT (0.81+/-0.1 versus 0.52+/-0.08N, P<0.01). CONCLUSIONS: Dividing anterior leaflet strut Chordae in sheep was associated acutely with regional LV systolic dysfunction near the Chordal insertion sites. Caution is necessary when embarking on procedures that cut second-order Chordae to treat ischemic mitral regurgitation, since this may compromise LV systolic function in ventricles that are already impaired.

Michael J Hasenkam - One of the best experts on this subject based on the ideXlab platform.

  • imbalanced Chordal force distribution causes acute ischemic mitral regurgitation mechanistic insights from Chordae tendineae force measurements in pigs
    The Journal of Thoracic and Cardiovascular Surgery, 2005
    Co-Authors: Sten Lyager Nielsen, Soren B Hansen, Katrine Nielsen, P K Paulsen, Michael J Hasenkam
    Abstract:

    Background Ischemic mitral regurgitation is caused by an imbalance of the entire mitral-ventricular complex. This interaction is mediated through the Chordae tendineae force distribution, which may perturb several elements of the mitral valve apparatus. Our objective was to investigate the association between the mitral valvular 3-dimensional geometric perturbations and Chordae tendineae force redistribution in a porcine model of acute ischemic mitral regurgitation. Methods In 9 pigs, acute ischemic mitral regurgitation was induced by repeated microembolization of the left circumflex coronary artery. Mitral leaflet coaptation geometry was determined by 2-dimensional echocardiography and reconstructed 3-dimensionally. Leading edge Chordal forces were measured by dedicated miniature force transducers at control and during ischemic mitral regurgitation. Results During acute ischemic mitral regurgitation, there was a decreased tension of the primary Chorda from the ischemic posterior left ventricular wall to the anterior leaflet (0.295 ± 0.063 N vs 0.336 ± 0.071 N [control]; P P Conclusions Acute ischemic mitral regurgitation due to posterior left ventricular wall ischemia was associated with focal Chordal and leaflet tethering at the nonischemic commissural portion of the mitral valve and a paradoxical decrease of the Chordal forces and relative prolapse at the ischemic site of the anterior mitral valve leaflet.

  • influence of anterior mitral leaflet second order Chordae tendineae on left ventricular systolic function
    Circulation, 2003
    Co-Authors: Sten Lyager Nielsen, Michael J Hasenkam, Ann F Bolger, Neil B Ingels, George T Daughters, Tomasz A Timek, Randall G Green, Paul Dagum, Craig D Miller
    Abstract:

    BACKGROUND: The contribution of anterior mitral leaflet second-order ("strut") Chordae tendineae to left ventricular (LV) systolic mechanics is debated; we measured the in vivo contribution of anterior Chordae tendineae (ACT) and posterior Chordae tendineae (PCT) to regional and global LV contractile function. METHODS AND RESULTS: Eight sheep had radiopaque markers implanted in the LV epicardium, partitioning the ventricle into 12 regions. Microminiature force transducers and snares were sutured to anterior leaflet "strut" Chordae originating from ACT and PCT papillary muscles. Chordal tension, marker images, and hemodynamic data were acquired before and after (CUT) severing ACT and PCT. Fractional area shrinkage and slope of the regional end-diastolic area-regional stroke work relation (r-PRSW) were computed for each LV region. CUT did not affect global LV systolic function but reduced FAS in LV segments near the PCT insertion site: equatorial posterior lateral (19+/-2% versus 16+/-2%, P<0.05), apical posterior lateral (23+/-4% versus 19+/-4%, P<0.05), and posterior medial LV segments (16+/-2% versus 13+/-2%, P<0.05). r-PRSW fell near both the ACT (equatorial anterior medial [84+/-8 versus 62+/-11 mm Hg, P<0.05] and lateral [73+/-7 versus 53+/-9 mm Hg, P<0.05]) and PCT (apical posterior medial [91+/-12 versus 67+/-17 mm Hg, P<0.05] and lateral [72+/-8 versus 59+/-9 mm Hg, P<0.05]) LV insertion sites. Maximum tension in PCT was higher than in ACT (0.81+/-0.1 versus 0.52+/-0.08N, P<0.01). CONCLUSIONS: Dividing anterior leaflet strut Chordae in sheep was associated acutely with regional LV systolic dysfunction near the Chordal insertion sites. Caution is necessary when embarking on procedures that cut second-order Chordae to treat ischemic mitral regurgitation, since this may compromise LV systolic function in ventricles that are already impaired.

Masashi Komeda - One of the best experts on this subject based on the ideXlab platform.

  • results of represervation of the Chordae tendineae during redo mitral valve replacement
    The Annals of Thoracic Surgery, 1996
    Co-Authors: Masashi Komeda, Joan Ivanov, John S Ikonomidis, Toshizumi Shirai, Richard D Weisel, Tirone E David
    Abstract:

    Background. Previous studies have shown that preservation of the Chordae tendineae improves early and late postoperative left ventricular function after mitral valve replacement. This report describes the results of represervation of the Chordae tendineae during redo mitral valve replacement in patients who had their Chordae tendineae preserved during their initial operation. Methods. Fifty-four patients undergoing reoperative mitral valve replacement with preservation of their Chordal annular attachments (Chordae group) were compared with 187 patients who had redo mitral valve replacement without preservation of the Chordae (nonChordae group). The interval between the initial operation and the reoperation was 8.7 ± 4.4 years in the Chordae group and 8.6 ± 4.9 years in the nonChordae group ( p = 0.315). Seventy-three patients underwent aortic valve replacement during their redo mitral valve replacement compared with 168 patients who had mitral valve replacement alone. There were 15 patients who had their Chordal attachments represerved during redo double-valve replacement. Results. In the Chordae group, intraoperative assessment revealed excellent Chordal connections between the preserved papillary muscles and the mitral annulus in all patients. One patient had adhesions between the preserved Chordae and the stent of the tissue valve. The Chordal attachments were preserved during insertion of the second valve in all patients. The incidence of low output syndrome and operative mortality in the Chordae group was 16.7% and 7.4%, respectively. In the nonChordae group, the incidence of low output syndrome was 27.3% ( p = 0.112 compared with the Chordae group) and the operative mortality was 13.4% ( p = 0.236 compared with the Chordae group). In patients with double-valve replacement, represervation of the Chordae was associated with a reduction in low output syndrome (0% versus 24%; p = 0.034) and mortality (6.7% versus 15.5%; p = 0.374). Conclusions. Preservation of the Chordal attachments between the papillary muscles and the mitral annulus can be accomplished during reoperative mitral valve replacement. Represervation of the Chordae tendineae may reduce postoperative low output syndrome, especially in high-risk patients undergoing redo double-valve replacement.

  • exploring better methods to preserve the Chordae tendineae during mitral valve replacement
    The Annals of Thoracic Surgery, 1995
    Co-Authors: Masashi Komeda, Abe Deandar, Julie R Glasson, Ann F Bolger, Y Tomizawa
    Abstract:

    Background. It is not known how best to resuspend the mitral Chordae tendineae during mitral valve replacement to optimize postoperative left ventricular (LV) systolic and diastolic function. Methods. Six different techniques to preserve the Chordae during mitral valve replacement were compared in 12 dogs using a nondistorting isovolumic technique: conventional, all Chordae severed; anterior, all Chordae preserved anteriorly; partial, anterior papillary muscle Chordae preserved anteriorly; posterior, all Chordae preserved posteriorly; oblique, anterior papillary muscle Chordae directed anteriorly and posterior papillary muscle Chordae posteriorly; and counter, opposite of oblique Chordal direction. Control measurements (no Chordal tension) were recorded between each experimental condition. Results. The oblique method tended to have the best LV systolic function versus the conventional method (E max = 4.0 ± 1.8 versus 3.3 ± 1.2 mm Hg/mL [mean ± standard deviation]; p = 0.08 by repeated-measures analysis of variance; physiologic intercept E cs00 = 20.3 ± 8.6 mL [ p max (3.3 ± 1.2 mm Hg/mL) than the oblique method, but a similar E eResults.00 (20.8 ± 8.1 mL; p max = 3.8 ± 1.2 mm Hg/mL; E eResults.00 = 19.7 ± 7.5 mL; p p Conclusions. In this isovolumic preparation in normal canine hearts, the oblique method of Chordal resuspension hearts, the oblique method of Chordal resuspension was associated with the best LV systolic function, whereas the counter technique impaired LV diastolic function. These preliminary results warrant further study in ejecting and failing hearts to determine conclusively which Chordal orientation best preserves LV performance after mitral valve replacement.

Kikuko Obase - One of the best experts on this subject based on the ideXlab platform.

  • elongation of Chordae tendineae as an adaptive process to reduce mitral regurgitation in functional mitral regurgitation
    European Journal of Echocardiography, 2016
    Co-Authors: Kikuko Obase, Lynn Weinert, Andrew Hollatz, Farhan Farooqui, Joseph D Roberts, Mohammed M Minhaj, Avery Tung, Mark A Chaney, Valluvan Jeevanandam
    Abstract:

    Aims In functional mitral regurgitation (FMR), increased leaflet area has been described as a remodelling compensatory mechanism. We hypothesized that Chordae tendineae elongation would also occur as part of this remodelling. In this study, the lengths of primary chords and measurements of mitral leaflets and annulus were compared with varying degrees of mitral regurgitation (MR). Methods and results We studied 58 patients who underwent three-dimensional (3D) transoesophageal echocardiography, including 38 with FMR and 20 with normal mitral valves (NL). The FMR group was divided into two subgroups according to two-dimensional vena contracta width (VCW). Three-dimensional datasets from transgastric or mid-oesophageal approach were used to measure primary Chordal length, coaptation length, inter-papillary muscle distances, and quantitative 3D measurements of the annulus and leaflets. Leaflet surface area was increased and coaptation length was decreased in FMR compared with NL. While no difference in other 3D measurement of annulus/leaflets was noted between the FMR subgroups, averaged Chordal length was shorter in patients with more severe FMR. Chords of the anterior leaflet in FMR with larger VCW were shorter compared with both NL and FMR with smaller VCW. In contrast, the chords of the posterior leaflet were longer in FMR with smaller VCW compared with the other two groups. Conclusion Our results suggest the posterior leaflet chords possibly remodel by elongating and contribute to reduced MR and that in a subgroup of FMR patients, the primary chords may remodel by shortening, resulting in augmented MR. This information could be useful in choosing strategy for FMR correction. [10.1093/ehjci/jew029][1] [1]: /lookup/doi/10.1093/ehjci/jew029

  • visualization and measurement of mitral valve Chordae tendineae using three dimensional transesophageal echocardiography from the transgastric approach
    Journal of The American Society of Echocardiography, 2015
    Co-Authors: Kikuko Obase, Andrew Hollatz, Farhan Farooqui, Valluvan Jeevanandam, Ken Saito, Kimberly L Kesner, Aaron Barry, Karima Addetia, Joseph D Roberts
    Abstract:

    Background The evaluation of the submitral apparatus is challenging from the conventional transesophageal approach. The aim of this study was to test the feasibility of using three-dimensional (3D) transesophageal echocardiographic (TEE) imaging from the transgastric approach to visualize the submitral apparatus and quantify the lengths of the Chordae tendineae by using multiplanar reconstruction analysis. Methods Twenty-two patients who had transgastric full-volume 3D TEE data sets before mitral valve surgery underwent surgical measurement of Chordal length. A short-axis plane at the Chordal level was extracted from the 3D data set to identify leaflet segments and the corresponding primary chords. Then, for each chord, the optimal plane was selected to visualize and measure the entire Chordal length from its origin at the leaflet margin to the papillary muscle tips. Measurements were performed at the phase of the cardiac cycle when Chordal length reached its maximum. Measured values were compared with surgical measurements using linear regression and Bland-Altman analyses. Result One hundred forty-six primary chords were measured intraoperatively. Three-dimensional TEE imaging was able to measure the lengths of all these chords. The surgical and 3D TEE measurements (mean, 1.96 ± 0.56 vs 1.93 ± 0.50 cm, respectively) correlated highly ( r  = 0.93, P Conclusion Transgastric 3D TEE imaging of the submitral apparatus allows visualization and accurate measurement of Chordae tendineae lengths, which may be useful for planning mitral valve repair, including percutaneous transcatheter procedures.

  • elongation of mitral valve Chordae tendineae is associated with increased leaflet surface area in patients with degenerative mitral regurgitation
    Journal of the American College of Cardiology, 2015
    Co-Authors: Kikuko Obase, Lynn Weinert, Andrew Hollatz, Farhan Farooqui, Joseph D Roberts, Mohammed M Minhaj, Avery Tung, Mark A Chaney, Valluvan Jeevanandam, Roberto M Lang
    Abstract:

    Degenerative mitral valve disease (DMVD) includes a spectrum of leaflet lesions, including elongated chords. In functional mitral regurgitation (FMR), leaflet adaptation has been described as a compensatory mechanism. Our aim was to determine the relationships between Chordal length and leaflet