scholarly journals In Vitro Mitral Valve Model with Unrestricted Ventricular Access: Using Vacuum to Close the Valve and Enable Static Trans-Mitral Pressure

2022 ◽  
Author(s):  
Sam E. Stephens ◽  
Alexander J. Kammien ◽  
Jacob C. Paris ◽  
Alexis P. Applequist ◽  
Neil B. Ingels ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Atmospheric Pressure ◽  
Muscle Force ◽  
In Vitro Models ◽  
Pressure Force ◽  
Mitral Valves ◽  
Regurgitant Flow ◽  
Force Closure ◽  
Valve Model

AbstractCurrent in vitro models of the left heart establish the pressure difference required to close the mitral valve by sealing and pressurizing the ventricular side of the valve, limiting important access to the subvalvular apparatus. This paper describes and evaluates a system that establishes physiological pressure differences across the valve using vacuum on the atrial side. The subvalvular apparatus is open to atmospheric pressure and accessible by tools and sensors, establishing a novel technique for experimentation on atrioventricular valves. Porcine mitral valves were excised and closed by vacuum within the atrial chamber. Images were used to document and analyze closure of the leaflets. Papillary muscle force and regurgitant flow rate were measured to be 4.07 N at 120 mmHg and approximately 12.1 ml/s respectively, both of which are within clinically relevant ranges. The relative ease of these measurements demonstrates the usefulness of improved ventricular access at peak pressure/force closure. Graphical abstract

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>

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.

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.

scholarly journals The role of strut chordae in mitral valve competence during annular dilation

Perfusion ◽  
2020 ◽  
pp. 026765912094134
Author(s):  
Samuel Taylor ◽  
Keith G Buchan ◽  
Daniel M Espino
Keyword(s):  
Mitral Valve ◽  
Systolic Pressure ◽  
Mitral Annulus ◽  
Chordae Tendineae ◽  
Mitral Valves ◽  
Significant Difference ◽  
Normal Configuration ◽  
Annular Dilation

Strut chordae, on their own, are not typically thought to aid mitral valve competence. The aim of this study is to assess whether strut chordae aid mitral valve competence during acute annular dilation. Twelve porcine hearts were dissected and tested using an in vitro simulator, with the mitral annulus tested in either a ‘normal’ or a dilated configuration. The normal configuration included a diameter of 30 mm, a posterior leaflet ‘radius’ of 15 mm and a commissural corner ‘radius’ of 7.5 mm; the dilated annular template instead used dimensions of 50 mm, 25 mm and 12.5 mm, respectively. Each mitral valve underwent ten repeat tests with a target systolic pressure of 100 mmHg. No significant difference in the pressure was detected between the dilated and regular annuli for the mitral valves tested (95 ± 3 mmHg cf. 95 ± 2 mmHg). However, the volume of regurgitation for a dilated annulus was 28 ml greater than for a valve with a normal annulus. Following severing of strut chordae, there was a significant reduction in the systolic pressure withstood before regurgitation by mitral valves with dilated annuli (60 ± 29 mmHg cf. 95 ± 2 mmHg for normal annular dimensions; p < 0.05). In conclusion, strut chordae tendineae may play a role in aiding mitral valve competence during pathophysiology.

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.

Mechanics of Healthy and Functionally Diseased Mitral Valves: A Critical Review

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Jean-Pierre M. Rabbah ◽  
Neelakantan Saikrishnan ◽  
Andrew W. Siefert ◽  
Arvind Santhanakrishnan ◽  
Ajit P. Yoganathan
Keyword(s):  
Mitral Valve ◽  
Left Atrium ◽  
Surgical Planning ◽  
Patient Specific ◽  
Mitral Valves ◽  
Medical Device Design ◽  
Unidirectional Flow ◽  
Patient Health

The mitral valve is a complex apparatus with multiple constituents that work cohesively to ensure unidirectional flow between the left atrium and ventricle. Disruption to any or all of the components—the annulus, leaflets, chordae, and papillary muscles—can lead to backflow of blood, or regurgitation, into the left atrium, which deleteriously effects patient health. Through the years, a myriad of surgical repairs have been proposed; however, a careful appreciation for the underlying structural mechanics can help optimize long-term repair durability and inform medical device design. In this review, we aim to present the experimental methods and significant results that have shaped the current understanding of mitral valve mechanics. Data will be presented for all components of the mitral valve apparatus in control, pathological, and repaired conditions from human, animal, and in vitro studies. Finally, current strategies of patient specific and noninvasive surgical planning will be critically outlined.

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