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We present a method for mounting a porcine aortic valve on a pulse duplicator to test its hydrodynamic properties. This method can be used to determine the change in hydrodynamics after the application of an experimental procedure or novel medical device prior to use in a large animal model.
The options for testing new cardiac procedures and investigative medical devices prior to use in an animal model are limited. In this study, we present a method for mounting a porcine aortic valve in a pulse duplicator to evaluate its hydrodynamic properties. These properties can then be evaluated before and after the procedure under investigation is performed and/or the investigative medical device is applied. Securing the inflow segment presents some difficulty owing to the lack of circumferential myocardium in the left ventricular outflow tract. This method addresses that issue by securing the inflow segment using the anterior leaflet of the mitral valve and then suturing the left ventricular free wall around the inflow fixture. The outflow segment is secured simply by inserting the fixture into an incision in the superior aspect of the aortic arch. We found that specimens had significantly different hydrodynamic properties before and after tissue fixation. This finding induced us to use fresh specimens in our testing and should be considered when using this method. In our work, we used this method to test novel intracardiac patch materials for use in the valvular position by performing an aortic valve neocuspidization procedure (Ozaki procedure) on the mounted porcine aortic valves. These valves were tested before and after the procedure to assess the change in hydrodynamic properties in comparison to the native valve. Herein, we report a platform for hydrodynamic testing of experimental aortic valve procedures that enables comparison with the native valve and between different devices and techniques used for the procedure under investigation.
Aortic valve disease represents a significant public health burden, particularly aortic stenosis, which affects 9 million people worldwide1. Strategies to address this disease are currently evolving and include aortic valve repair and aortic valve replacement. In the pediatric population especially, there is a significant incentive to repair rather than replace the valve since currently available prostheses are prone to structural valve degeneration (SVD) and are not growth tolerant, requiring reoperation for re-replacement as the patient grows. Even the Ross procedure, which replaces the diseased aortic valve (AV) with the native pulmonary val....
All research was performed in compliance with institutional guidelines for the care of animals.
1. Considerations and preparations for the experiment
The representative data collected from the pulse duplicator includes regurgitation fraction (RF), effective orifice area (EOA), and mean positive pressure difference (PPD). The RF and EOA, in particular, are used in the ISO standards for prosthetic valves (ISO 5840) and will be important to collect if prosthetic valve products are under investigation. The PPD offers information regarding how much pressure is required to open the valve and is commonly referenced when discussing prosthetic valve replacement
The method presented here provides a platform for hydrodynamic testing of the AV in order to examine the effect of an experimental procedure or a novel medical device. By mounting the native aortic valve on a pulse duplicator machine, we are able to determine the effect of the experimental procedure on all the hydrodynamic parameters used in the investigation and approval of novel valve prostheses (ISO 5840). This provides an opportunity to fine-tune procedures and prostheses prior to use in a large animal model.
We would like to thank the lab of Dr. Gordana Vunjak-Novakovic, including Julie Van Hassel, Mohamed Diane, and Panpan Chen, for allowing us to use cardiac waste tissue from their experiments. This work was supported by the Congenital Heart Defect Coalition in Butler, NJ, and the National Institutes of Health in Bethesda, MD (5T32HL007854-27).
....Name | Company | Catalog Number | Comments |
3D Printer | Ultimaker | Ultimaker S5 | Used for printing custom fixtures for hydrodynamic testing |
Crile-Wood Needle Driver | Emerald Instruments | 2.0638.15 | Used for suturing ventricle |
Debakey Forceps | Jarit | 320-110 | Used for dissection and sample preparation (can use multiple if working with an assistant) |
Ethanol 200 proof | Decon Labs Inc. | DSP-MD.43 | Used for fixed tissue storage |
Formalin 10% | Epredia | 5701 | Used for tissue fixation |
Gerald Forceps | Jarit | 285-126 | Used for dissection and sample preparation |
Glass jars | QAPPDA | B07QCP54Z3 | Used for tissue storage |
Glutaraldehyde 25% | Electron Microscopy Sciences | 16400 | Used for tissue fixation |
HEPES 1 M buffer solution | Fisher | BP299-100 | Used to make glutaraldehyde 0.6% |
Mayo Scissors | Jarit | 099-200 | Used for cutting suture |
Metzenbaum Scissors | Jarit | 099-262 | Used for dissection and sample preparation |
O-ring | Sterling Seal & Supply Inc. | AS568-117 | Used as a gasket on the end of the 3D printed fixtures |
Polylactic acid resin | Ultimaker | 1609 | Used for 3D printing fixtures |
Polyproplene suture | Covidien | VP-762-X | Used for suturing ventricle, tapered needle |
Pulse Duplicator | BDC Laboratories | HDTi-6000 | Used for hydrodynamic testing |
Silk ties | Covidien | S-193 | Used for ligating coronary arteries |
Tonsil Clamp | Aesculap | BH957R | Used for coronary artery dissection |
Zip ties (6 inch) | Advanced Cable Ties, Inc. | AL-06-18-9-C | Used for securing sample to fixtures, 157.14 mm long (6 inches), 2.5 mm wide |
Zip ties (8 inch) | GTSE | GTSE-20025B.1000 | Used for securing sample to fixtures, 203 mm long (8 inches), 2.5 mm wide |
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