In Vitro Measurement of the Coaptation Force Distribution in Normal and Functional Regurgitant Porcine Mitral Valves

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
John Adams ◽  
Malachy J. O'Rourke
Keyword(s):  
Mitral Valve ◽  
Myocardial Ischemia ◽  
Papillary Muscle ◽  
Force Distribution ◽  
Papillary Muscles ◽  
Flow Loop ◽  
Static Tests ◽  
Mitral Valves ◽  
Static Conditions

Closure of the left atrioventricular orifice is achieved when the anterior and posterior leaflets of the mitral valve press together to form a coaptation zone along the free edge of the leaflets. This coaptation zone is critical to valve competency and is maintained by the support of the mitral annulus, chordae tendinae, and papillary muscles. Myocardial ischemia can lead to an altered performance of this mitral complex generating suboptimal mitral leaflet coaptation and a resultant regurgitant orifice. This paper reports on a two-part experiment undertaken to measure the dependence of coaptation force distribution on papillary muscle position in normal and functional regurgitant porcine mitral heart valves. Using a novel load sensor, the local coaptation force was measured in vitro at three locations (A1–P1, A2–P2, and A3–P3) along the coaptation zone. In part 1, the coaptation force was measured under static conditions in ten whole hearts. In part 2, the coaptation force was measured in four explanted mitral valves operating in a flow loop under physiological flow conditions. Here, two series of tests were undertaken corresponding to the normal and functional regurgitant state as determined by the position of the papillary muscles relative to the mitral valve annulus. The functional regurgitant state corresponded to grade 1. The static tests in part 1 revealed that the local force was directly proportional to the transmitral pressure and was nonuniformly distributed across the coaptation zone, been strongest at A1–P1. In part 2, tests of the valve in a normal state showed that the local force was again directly proportional to the transmitral pressure and was again nonuniform across the coaptation zone, been strongest at A1–P1 and weakest at A2–P2. Further tests performed on the same valves in a functional regurgitant state showed that the local force measured in the coaptation zone was directly proportional to the transmitral pressure. However, the force was now observed to be weakest at A1–P1 and strongest at A2–P2. Movement of the anterolateral papillary muscle (APM) away from both the annular and anterior–posterior (AP) planes was seen to contribute significantly to the altered force distribution in the coaptation zone. It was concluded that papillary muscle displacement typical of myocardial ischemia changes the coaptation force locally within the coaptation zone.

Insights From In-Vitro Flow Visualization Into the Mechanism of Systolic Anterior Motion of the Mitral Valve in Hypertrophic Cardiomyopathy Under Steady Flow Conditions

1992 ◽  
Vol 114 (3) ◽  
pp. 406-413 ◽  
Author(s):  
X. P. Lefebvre ◽  
A. P. Yoganathan ◽  
R. A. Levine
Keyword(s):  
Mitral Valve ◽  
Flow Field ◽  
Flow Visualization ◽  
Papillary Muscle ◽  
Left Ventricular ◽  
Outflow Tract ◽  
Papillary Muscles ◽  
Systolic Anterior Motion ◽  
Septal Hypertrophy

Hypertrophic obstructive cardiomyopathy is a heart disease characterized by a thickened interventricular septum which narrows the left ventricular outflow tract, and by systolic anterior motion (SAM) of the mitral valve which can contact the septum and create dynamic subaortic obstruction. The most common explanation for SAM has been the Venturi mechanism which postulates that septal hypertrophy, by narrowing the outflow tract, produces high velocities and thus low pressure between the mitral valve and the septum, causing the valve leaflets to move anteriorly. This hypothesis, however, fails to explain why SAM often begins early in systole, when outflow tract velocities are low or negligible or why it may occur in the absence of septal hypertrophy. The goal of this study was therefore to investigate an alternative hypothesis in which structural abnormalities of the papillary muscles act as a primary cause of SAM by altering valve restraint and thereby changing the geometry of the closed mitral apparatus and its relationship to the surrounding flow field. In order to test this hypothesis, an in vitro model of the left ventricle which included an explanted human mitral valve with intact chords and papillary muscle apparatus was constructed. Flow visualization was used to observe the ventricular flow field and the mitral valve geometry. Displacing the papillary muscles anteriorly and closer to each other, as observed clinically in patients with cardiomyopathy and obstruction produced SAM in the absence of septal hypertrophy. Flow could be seen impacting on the upstream (posterior) surface of the leaflets; such flow is capable of producing form drag forces which can initiate and maintain SAM. In contrast, increasing septal hypertrophy to narrow the outflow tract and create velocities as high as 3.3 m/s did not produce SAM in the absence of papillary muscle displacement, despite an increase in the calculated lift forces. Therefore, primary abnormalities of the papillary muscle-mitral valve apparatus can alter the relationship of the mitral valve to the surrounding flow field in such a way that SAM is generated, whereas the Venturi mechanism, induced by septal hypertrophy alone, is insufficient to do so with a normally positioned and tethered valve.

In Vitro Stretches of the Mitral Valve Anterior Leaflet Under Edge-to-Edge Repair Condition

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Zhaoming He ◽  
Bo Gao ◽  
Shamik Bhattacharya ◽  
Tyler Harrist ◽  
Sibi Mathew ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Central Region ◽  
Anterior Leaflet ◽  
Flow Loop ◽  
Mitral Valves ◽  
Double Frequency ◽  
Significant Difference ◽  
Loading And Unloading ◽  
Single Suture

Mitral valve edge-to-edge repair (ETER) alters valve mechanics, which may impact efficacy and durability of the repair. The objective of this paper was to quantify stretches in the central region of the anterior leaflet of the mitral valve after ETER with a single suture and 6 mm suture. Sixteen markers, forming a 4×4 array, were attached onto the central region of the mitral valve anterior leaflet. The mitral valve was subjected to ETER with a single suture and 6 mm suture, and mounted in an in vitro flow loop simulating physiological conditions. Images of the marker array were used to calculate marker displacement and stretch. A total of 9 mitral valves were tested. Two peak stretches were observed during a cardiac cycle, one in systole and the other in diastole under mitral valve edge-to-edge repair condition. The major principal (radial) stretch during systole was significantly greater than that during diastole. However, there was no significant difference between the minor principal (circumferential) stretch during diastole and that during systole. In addition, there were no significant differences in the radial and circumferential, or areal stretches and stretch rates during diastole between the single suture and 6 mm suture. The ETER subjects the mitral valve leaflets to double frequency of loading and unloading. Minor change in suture length may not result in a significant load difference in the central region of the anterior leaflet during diastole.

Stereoscopic Particle Image Velocimetry of Native Ovine Mitral Valves in a Pulsatile Left Heart Simulator

2012 ◽  
Author(s):  
Jean-Pierre Rabbah ◽  
Neelakantan Saikrishnan ◽  
Ajit P. Yoganathan
Keyword(s):  
Particle Image Velocimetry ◽  
Mitral Valve ◽  
Computational Models ◽  
Particle Image ◽  
Numerical Models ◽  
Stereoscopic Particle Image Velocimetry ◽  
Patient Specific ◽  
Flow Loop ◽  
Mitral Valves ◽  
Image Velocimetry

Patient specific mitral valve computational models are being actively developed to facilitate surgical planning. These numerical models increasingly employ more realistic geometries, kinematics, and mechanical properties, which in turn requires rigorous experimental validation [1]. However, to date, native mitral flow dynamics have not been accurately and comprehensively characterized. In this study, we used Stereoscopic Particle Image Velocimetry (SPIV) to characterize the ventricular flow field proximal to a native mitral valve in a pulsatile experimental flow loop.

Echocardiography of congenital mitral valve disorders: echocardiographic–morphological comparisons

2014 ◽  
Vol 24 (6) ◽  
pp. 1030-1048 ◽  
Author(s):  
Norman H. Silverman
Keyword(s):  
Mitral Valve ◽  
Papillary Muscle ◽  
Mitral Stenosis ◽  
Congenital Abnormalities ◽  
High Morbidity ◽  
Papillary Muscles ◽  
Anatomical Correlation ◽  
Mitral Prolapse ◽  
Autopsy Specimens ◽  
Double Orifice

AbstractI surveyed our echocardiographic database of the years between 1998 and 2012 for congenital abnormalities of the mitral valve in patients over 14 years. A total of 249 patients with mitral valve abnormalities were identified. Abnormalities included clefts in the mitral valve in 58 patients, double orifice of the mitral valve in 19, mitral stenosis with two papillary muscles in 72, and mitral stenosis with one papillary muscle in 51 patients. Supravalvar rings were found in 35 patients with a single papillary muscle, and mitral stenoses with two papillary muscles were found in 22 patients. Mitral prolapse occurred in 44 patients and mitral valvar straddle in five patients. The patients were evaluated by all modalities of ultrasound available over the course of time. Although some lesions were isolated, there were many lesions in which more than one mitral deformity presented in the same patient. The patients are presented showing anatomical correlation with autopsy specimens, some of which came from the patients in this series, and others matched to show correlative anatomy. These lesions remain rare as a group and continue to have high morbidity and mortality.

scholarly journals Validation test on 3d heart phantom for mitral valve leaflet tracking

2021 ◽  
Vol 22 (2) ◽  
pp. 717
Author(s):  
Lina Farhana Mahadi ◽  
Nabilah Ibrahim ◽  
Shahnoor Shanta ◽  
Hideyuki Hasegawa
Keyword(s):  
Mitral Valve ◽  
Water Tank ◽  
Font Size ◽  
Mitral Valve Leaflet ◽  
Mitral Valves ◽  
True Value ◽  
Video Frames ◽  
Validation Experiment ◽  
Temporal Rate

<p><span style="font-family: 'Times New Roman',serif; font-size: 9pt; mso-bidi-font-size: 11.0pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US"><span style="font-family: 'Times New Roman',serif; font-size: 9pt; mso-bidi-font-size: 11.0pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US">Mitral valve movement is essential to be identified in order to monitor the abnormality of blood flow in right side of heart. The estimation and tracking of mitral valve has seldom been investigated since it required high temporal rate to scan the echocardiography images and it depends on the operator to capture the low-speckle and-noise images. This study presents the validation experiment performed on heart phantom made of t</span><span style="font-family: 'Times New Roman',serif; font-size: 9pt; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US">hermoplastic polyurethane (TPU) filament which the objective is to validate the previous </span><span style="font-family: 'Times New Roman',serif; font-size: 9pt; mso-bidi-font-size: 11.0pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US">features tracking technique implemented in mitral valve locating in video frames using Kanade-Lucas-Tomasi (KLT) algorithm. The outcome was able to automatically detect the edge of mitral valve and thus in future, it manages to predict the flowing of blood pattern. An in-vitro experiment was conducted which involved a valve phantom scanning in water tank that connected to water pump. It was found in this study that the technique capable to detect and visualize the mitral valve up to 59 frames in 2.36 secondsby tracking the features of minimum eigenvalue within the selected region. It was also produced a good agreement of valve distance between the true value and the measured one, which achieved the minimum of 88% similarity. This yielded the validation of the proposed technique to track and visualize the mitral valves. </span></span></p>

P365Does papillary muscle ablation affect mitral valve function: a single centre experience

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
J Stassen ◽  
D Dilling ◽  
J Vijgen ◽  
J Schurmans ◽  
P Koopman
Keyword(s):  
Mitral Valve ◽  
Papillary Muscle ◽  
Delayed Enhancement ◽  
Papillary Muscles ◽  
Premature Ventricular Contractions ◽  
Valve Function ◽  
History Of ◽  
Study Population ◽  
The Impact

Abstract Introduction Ventricular arrhythmias from papillary muscles (PMs) often require extensive catheter ablation (CA). Not much is known about the mitral valve (MV) function after these extensive catheter ablations. Purpose The goal of this study was to determine the impact of papillary muscle CA on MV function.  Methods We retrospectively examined echocardiographic measurements in 21 patients with frequent premature ventricular contractions (PVCs) originating from the mitral PMs who underwent CA, dating from October 2012 till November 2018. We assessed MV function at baseline, 6 month and last follow-up. Degree of mitral regurgitation (MR) was graded as mild (ERO &lt;0,2 cm2, regurgitation volume (RV) &lt;30ml), moderate (ERO 0,2-0,4cm2, RV 30-59ml) or severe (ERO ≥0,4cm2, RV  ≥60ml). Significant MR was defined as a 2+ change. Results Mean age of the study population was 59,7 (27-80)years, 52,4% was female. 2 patients were known with ischemic heart disease. There was a family history of sudden cardiac death in 3 patients. Main symptoms at presentation were palpitations (66,7%), fatigue (33,3%), dyspnea (33,3%, all NYHA 2), dizziness (28,6%), angina pectoris (14,3%) and syncope (4,8%). Beta blocker (71,4%), flecaïnide (23,8%), amiodarone (9,5%), sotalol (4,8%) and propafenon (4,8%) were the most frequent medical therapies before CA. Mean burden of PVC before ablation was 15 574 (2000-39700)/24h. In 28,6% non sustained VT was documented, 1 patient suffered a sustained episode of VT.  After ablation, mean burden of PVC was reduced to 1331 (0-14200)/24h. Redo ablation was necessary in 28,6% of patients. PVCs orginated from the anterolateral PM in 33,3% and from the posteromedial PM in 66,7%. Mean troponin release was 9.4 ± 5.3 µg/l, mean troponin hs (since 2016) was 1591.0 ±658.6ng/ml. CMR was done in 14/21 (66,7%) patients before CA. In 5 out of 14 patients (35,7%), delayed enhancement at the papillary muscles was noticed. In 5 patients without delayed enhancement, CMR was repeated after CA. In all these 5 patients, delayed enhancement was noticed at the level of the papillary muscles.  At baseline, 15/21 had mild, 5/21 moderate and  1/21 severe MR. There was no significant chance in MR at 6m follow-up with 15/21 having mild and  6/21 moderate MR (p 0.58) with 1 patient having a significant MR 2+ change. At last follow-up (23.7 ± 22.6 months) there was also no significant chance in MR with 15/21 having mild and 6/21 moderate MR (p 0.58) without a significant MR 2+ change.  Complications occurred in 1 patient (transient AV blok). No patients died during follow up.  Conclusions Although PM ablation was associated with time extensive ablation, significant troponine release and documented delayed enhancement on post ablation MRI, there was no risk of additional valvular dysfunction after CA in this study. Larger studies will be necessary to confirm these findings.

scholarly journals Mechanical testing of glutaraldehyde cross-linked mitral valves. Part one: In vitro mechanical behaviour

2020 ◽  
pp. 095441192097589
Author(s):  
Rhiannon Northeast ◽  
Matthew Constable ◽  
Hanna E Burton ◽  
Bernard M Lawless ◽  
Vera Gramigna ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Peak Pressure ◽  
Systolic Pressure ◽  
Initial Assessment ◽  
Cross Linking ◽  
Mitral Valves ◽  
Endothelial Denudation ◽  
Glutaraldehyde Solution ◽  
Bioprosthetic Mitral Valve

The aim of this study was to perform an initial assessment, in vitro, of the feasibility of using a glutaraldehyde cross-linked porcine mitral valve to retain acute functionality, focusing on assessing mitral regurgitation. Six porcine hearts were tested using an in vitro simulator. Testing was repeated following cross-linking of mitral valves; where cross-linking was achieved by placing them in a glutaraldehyde solution. The simulator enabled systolic pressure on the ventricular side of the valve to be mimicked. Following testing, mitral valve leaflets underwent Scanning Electron Microscopy of the ventricular surface of both the anterior and posterior leaflets (1 cm2 samples). The peak pressure withstood by cross-linked valves was significantly lower than for untreated valves (108 mmHg cf. 128 mmHg for untreated valves; p  < 0.05). The peak pressure was typically reached 0.5 s later than for the untreated valve. While both cross-linked and untreated valves exhibited endothelium denudation, the unfixed valve had less endothelial loss. Glutaraldehyde cross-linking of porcine mitral valves may be of potential value in assessing improved bioprosthetic mitral valve replacements. However, a more immobile valve exhibiting endothelial denudation (i.e. sclerosis) was a possible concerns identified following in vitro acute assessment.

A Novel Method to Measure Mitral Valve Chordal Tension

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Zhaoming He ◽  
Christopher Jowers
Keyword(s):  
Mitral Valve ◽  
Force Sensor ◽  
New Method ◽  
Ring Size ◽  
Mitral Valves ◽  
Novel Method ◽  
Healthy Functioning ◽  
Leaflet Coaptation

Proper leaflet coaptation of the mitral valve is vital for a healthy functioning heart. Chordal tension directly affects leaflet coaptation. The C-shaped transducer used previously to measure chordal tension was too big for tension measurement of multiple chordae and their branches. A new method is needed to measure chordal tension with minimum interference with chord and leaflet motion. The method was to extrapolate longitudinal chordal tension from transverse chordal fibril force measured by inserting a small elliptical AIFP4 sensor from MicroStrain Inc. (Williston, VT) through a chord. Sensitivity of the method has been tested with the sensor implanted in chordae, and error of the method has been estimated at various sensor deviation angles. Intact porcine and ovine hearts were used to measure mitral valve strut and marginal chordal tensions at static transmitral pressures of 120mmHg and 160mmHg under an in vitro condition. The results obtained from the AIFP4 sensor were similar to the results obtained previously by C-shaped transducers in the porcine mitral valves. The sensor output errors increased with the increase in sensor deviation angle in the chord at a peak systolic tension. Strut chordal tensions of four ovine mitral valves of Edwards ring size M 28 were 0.29±0.06N at the transmitral pressure of 120mmHg. The tension of 18 porcine strut chordae of porcine mitral valves of Edwards ring size M 32 was 1.00±0.42N at the transmitral pressures of 120mmHg. The tension of 22 anterior leaflet marginal chordae from porcine mitral valves of Edwards ring size M 32 was 0.10±0.04N at the transmitral pressure of 120mmHg. A new method using an AIFP4 miniature force sensor to measure mitral valve chordal tension indirectly is successfully developed. This force sensor works well in measuring mitral valve chordal tension at an in vitro hydrostatic transmitral pressure. The size and simple fixation of the sensor make it favorable for chordal tension measurement of multiple chordae and their branches under in vitro or in vivo conditions with minimal interference with chordal geometry and dynamics.

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.

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