Mitral Annular Dilatation and Papillary Muscle Dislocation Without Mitral Regurgitation in Sheep

Circulation ◽  
1999 ◽  
Vol 100 (suppl_2) ◽  
Author(s):  
G. Randall Green ◽  
Paul Dagum ◽  
Julie R. Glasson ◽  
George T. Daughters ◽  
Ann F. Bolger ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Mitral Regurgitation ◽  
Papillary Muscle ◽  
Ex Vivo ◽  
Mitral Annulus ◽  
Functional Mitral Regurgitation ◽  
3 Dimensional ◽  
Annular Dilatation ◽  
Muscle Geometry ◽  
Anterior Papillary Muscle

Background —Asymmetrical mitral annular (MA) dilatation and papillary muscle dislocation are implicated in the pathogenesis of functional mitral regurgitation (MR). Methods and Results —To determine the mechanism by which annular and papillary muscle geometric alterations result in MR, we implanted radiopaque markers in the left ventricle, mitral annulus, anterior and posterior mitral leaflets, and papillary muscle tips and bases in 2 groups of sheep. One group served as controls (CTL, n=7); an experimental group (EXP, n=9) underwent topical phenol application to obliterate anterior annular and leaflet muscle (confirmed histologically ex vivo). After 1 week of recovery, markers were imaged with biplane videofluoroscopy, and hemodynamic data were recorded. MA area (computed from 3-dimensional marker coordinates) was 11% to 13% larger in the EXP group than in the CTL group ( P <0.05 by ANOVA). This area increase resulted exclusively from intercommissural axis increase except in 1 heart with large (>1 cm) increases in both the intercommissural and septolateral annular axes. The anterior papillary muscle tip in EXP was displaced from CTL by 2.9±0.23 mm toward the anterolateral left ventricle and 2.5±0.12 mm toward the mitral annulus at end systole; the posterior papillary muscle geometry was unchanged. Transthoracic echocardiography revealed MR only in the heart exhibiting biaxial annular enlargement. Conclusions —MA dilatation in the intercommissural dimension with anterior papillary muscle tip displacement toward the annulus is insufficient to produce MR in sheep. Functional MR may require MA dilatation in the septolateral axis, as observed with proximal circumflex coronary occlusion.

scholarly journals Ex Vivo Model of Functional Mitral Regurgitation Using Deer Hearts

2020 ◽  
Author(s):  
Michal Jaworek ◽  
Andrea Mangini ◽  
Edoardo Maroncelli ◽  
Federico Lucherini ◽  
Rubina Rosa ◽  
...  
Keyword(s):  
Mitral Regurgitation ◽  
Ex Vivo ◽  
Mitral Annulus ◽  
Left Ventricular ◽  
Functional Mitral Regurgitation ◽  
Pathological State ◽  
Preclinical Research ◽  
Ex Vivo Model ◽  
Mitral Valves ◽  
Feasibility Assessment

Abstract Transcatheter therapies are emerging for functional mitral regurgitation (FMR) treatment, however there is lack of pathological models for their preclinical assessment. We investigated the applicability of deer hearts for this purpose. 8 whole deer hearts were housed in a pulsatile flow bench. At baseline, all mitral valves featured normal coaptation. The pathological state was induced by 60-minutes intraventricular constant pressurization. It caused mitral annulus dilation (antero-posterior diameter increase from 31.8 ± 5.6 mm to 39.5 ± 4.9 mm, p = 0.001), leaflets tethering (maximal tenting height increase from 7.3 ± 2.5 mm to 12.7 ± 3.4 mm, p < 0.001) and left ventricular diameter increase (from 67.8 ± 7.5 mm to 79.4 ± 6.5 mm, p = 0.004). These geometrical reconfigurations led to restricted mitral valve leaflets motion and leaflet coaptation loss. Preliminary feasibility assessment of two FMR treatments was performed in the developed model. Deer hearts showed ability to dilate under constant pressurization and have potential to be used for realistic preclinical research of novel FMR therapies.

Abstract 16874: Papillary Muscle Approximation Relieves Tethering Forces and Improves Systolic Mitral Valve Kinematics in an Ex-Vivo Model of Functional Mitral Regurgitation

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Samantha Zhan Moodie ◽  
Kirthana Sreerangathama Suresh ◽  
Dongyang Xu ◽  
Muralidhar Padala
Keyword(s):  
Mitral Valve ◽  
Mitral Regurgitation ◽  
Papillary Muscle ◽  
Ex Vivo ◽  
Functional Mitral Regurgitation ◽  
Current Standard ◽  
Ex Vivo Model ◽  
Mitral Valves ◽  
Baseline Values ◽  
Mitral Valve Geometry

Introduction: Undersizing annuloplasty (UA), which is the current standard to correct functional mitral regurgitation (FMR) is effective, but the resulting unphysiological systolic geometry causes FMR recurrence. On the other hand, papillary muscle approximation (PMA), a sub-annular technique, reduces inter-papillary separation and tethering forces, mobilizing the leaflets. Objective: To investigate the effect of PMA on mitral valve tethering forces and systolic coaptation geometry, compared to UA. Methods: A left heart model with pig mitral valves was used to create a tethered mitral valve geometry and to perform surgical repairs ( Fig. A ). Mitral valve geometry, and marginal and strut chordal forces acting on both leaflets were measured. Eight individual pig valves (n=8) were studied, with hemodynamic and mechanics data acquired at normal geometry (BASELINE) ( Fig. B) , after tethering (FMR) ( Fig. C) , undersizing annuloplasty (UA) to size 34 (Edwards Lifesciences Physio ring) ( Fig. D) , papillary muscle approximation (PMA), and combination (PMA+UA). Results: Tenting height, which increased after FMR, was least with PMA (0.46 cm± 0.21) and PMA+UA (0.50± 0.16) but remained significantly high with UA (0.73±0.21, p=0.03) ( Fig. E ). Excursion angles of anterior and posterior leaflets were restored close to baseline values after PMA and PMA+UA but remained significantly tethered after UA ( Fig. F & G ). Tethering of the valve increased the strut and marginal chordae forces from 0.47 and 0.14 N to 0.89 and 0.21 N, an increase of 89% and 50% respectively. PMA reduced the forces by 47% and 34%, and PMA+UA reducing it by 43% and 34%to 0.51 while UA only reduced it by 15% and 20% ( Fig. H & I ). Conclusion: PMA significantly reduced the tethering forces on both marginal and strut chordae of both leaflets. Decrease in tethering forces restored the physiologically favorable valve geometry enabling better leaflet mobility and coaptation compared to UA.

scholarly journals Characterization of 3-dimensional papillary muscle displacement in in vivo ovine models of ischemic/functional mitral regurgitation

2019 ◽  
Vol 157 (4) ◽  
pp. 1444-1449 ◽  
Author(s):  
Wolfgang Bothe ◽  
Tomasz A. Timek ◽  
Frederick A. Tibayan ◽  
Mario Walther ◽  
George T. Daughters ◽  
...  
Keyword(s):  
Mitral Regurgitation ◽  
Papillary Muscle ◽  
Functional Mitral Regurgitation ◽  
3 Dimensional

A Novel Quantitative Ex Vivo Model of Functional Mitral Regurgitation

2020 ◽  
Vol 15 (4) ◽  
pp. 329-337
Author(s):  
Chetan Pasrija ◽  
Rachael Quinn ◽  
Mehrdad Ghoreishi ◽  
Thomas Eperjesi ◽  
Eric Lai ◽  
...  
Keyword(s):  
Mitral Regurgitation ◽  
Ex Vivo ◽  
3D Structure ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Functional Mitral Regurgitation ◽  
Ex Vivo Model ◽  
3 Dimensional ◽  
Structured Light Scanner ◽  
Repair Techniques

Objective Durability of mitral valve (MV) repair for functional mitral regurgitation (FMR) remains suboptimal. We sought to create a highly reproducible, quantitative ex vivo model of FMR that functions as a platform to test novel repair techniques. Methods Fresh swine hearts ( n = 10) were pressurized with air to a left ventricular pressure of 120 mmHg. The left atrium was excised and the altered geometry of FMR was created by radially dilating the annulus and displacing the papillary muscle tips apically and radially in a calibrated fashion. This was continued in a graduated fashion until coaptation was exhausted. Imaging of the MV was performed with a 3-dimensional (3D) structured-light scanner, which records 3D structure, texture, and color. The model was validated using transesophageal echocardiography in patients with normal MVs and severe FMR. Results Compared to controls, the anteroposterior diameter in the FMR state increased 32% and the annular area increased 35% ( P < 0.001). While the anterior annular circumference remained fixed, the posterior circumference increased by 20% ( P = 0.026). The annulus became more planar and the tenting height increased 56% (9 to 14 mm, P < 0.001). The median coaptation depth significantly decreased (anterior leaflet: 5 vs 2 mm; posterior leaflet: 7 vs 3 mm, P < 0.001). The ex vivo normal and FMR models had similar characteristics as clinical controls and patients with severe FMR. Conclusions This novel quantitative ex vivo model provides a simple, reproducible, and inexpensive benchtop representation of FMR that mimics the systolic valvular changes of patients with FMR.

An Ex Vivo Model of Left Ventricular Dilation and Functional Mitral Regurgitation to Facilitate the Development of Surgical Techniques

2013 ◽  
Vol 16 (6) ◽  
pp. 329
Author(s):  
Eric Monnet ◽  
Kristal Pouching
Keyword(s):  
Mitral Regurgitation ◽  
Papillary Muscle ◽  
Ex Vivo ◽  
Surgical Techniques ◽  
Left Ventricular ◽  
Functional Mitral Regurgitation ◽  
Ex Vivo Model ◽  
Ischemic Disease ◽  
Posterior Papillary Muscle ◽  
Annular Dilation

<p><b>Objective:</b> Functional mitral regurgitation (FMR) is a common sequelae of myocardial ischemic disease. It results from annular dilation and outward rotation of the posterior papillary muscle. Different surgical techniques are under investigation for the treatment of FMR. However, an ex vivo model of FMR would be valuable to develop and compare the effect of techniques on the geometry of the left ventricle and the correction of FMR.</p><p><b>Methods:</b> FMR was induced in explanted ovine hearts (n = 12) by manual dilation of the mitral annulus or by posterior papillary muscle repositioning with a patch. Left ventricular dimensions were measured. Mitral regurgitant volume (MRV) was measured in a continuous flow system.</p><p><b>Results:</b> Annular dilation significantly increased MRV from 93.0 � 110.4 to 472.2 � 211.8 mL/min (<i>P</i> = 0.031), and the patch increased it from 37.8 � 55.2 to 365 � 189.6 mL/min (<i>P</i> = 0.031), with no significant differences between the 2 groups. When both techniques were applied, MRV significantly increased to 1383.5 � 567.0 mL/min (<i>P</i> = 0.0005). The left ventricular sphericity index decreased from 3.25 � 0.7 to 2.34 � 0.6 (<i>P</i> = 0.0025) after application of the patch. The posterior papillary muscle was displaced after patch placement, following an outward rotation.</p><p><b>Conclusion:</b> This ex vivo model reproduces annular dilation and outward rotation of the posterior papillary muscle, which are both present during FMR after ischemic myocardial disease. This model could be used to evaluate and compare interventions to treat FMR.</p>

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