preparation of left ventricular outflow tract (lvot) from porcine heart for cannulation 

安装猪主动脉瓣流体动力学特性的评价

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 valve (PV), requires a prosthesis or graft in the pulmonary position that is also subject to SVD and often limited growth tolerance2. New approaches to aortic valve disease are being developed, and there is a need for testing in a biologically relevant context prior to application in a large animal model.
We have developed a method for testing a porcine AV that can provide insights into the function of the valve before and after an investigational procedure or application of a novel medical device. By mounting the porcine AV on a commercially available pulse duplicator machine, we are able to compare the hydrodynamic characteristics that are commonly used in the investigation and ultimately approval of valve prostheses, including regurgitation fraction (RF), effective orifice area (EOA), and mean positive pressure difference (PPD)3,4. The intervention can then be fine-tuned in a biologically relevant context before use in a large animal model, thus limiting the number of animals needed to produce a procedure or prosthesis that can be used in humans. The hearts used for this experiment can be obtained from the local abattoir or waste tissue from other experiments, so it is not necessary to sacrifice an animal solely for the purposes of this experiment.
In our work, we used this method to develop a novel patch material for valve repair and replacement. We tested the hydrodynamic function of a variety of patch materials by performing an aortic valve neocuspidization procedure (Ozaki procedure5,6,7) on porcine AVs and testing them in the pulse duplicator before and after the procedure. This enabled us to fine-tune the material based on its hydrodynamic performance. Thus, this method provides a platform for hydrodynamic testing of experimental procedures and novel medical devices for use on the AV prior to application&#160;in a large animal model.

作者聚焦：在开始大型动物研究之前推进心脏手术测试 

用于实验性主动脉瓣手术和新型医疗设备流体动力学测试的 离体 猪模型

Limited options exist for testing new cardiac procedures and investigative medical devices before use in a large animal model. Our protocol provides the opportunity to fine-tune such procedures and devices in a biologically and anatomically relevant context prior to embarking on large animal studies. Other techniques for mounting an aortic valve on a pulse duplicator require inserting or fixing a rigid structure to the aortic valve annulus, thus distorting the valve's hydrodynamic properties.Our protocol offers an innovative way to cannulate the LVOT so that all measured hydrodynamic properties are valid. This method is designed to assess the viability of leaflet substitution materials for use as a valve repair patch or prosthesis. It is a pivotal tool for our future research in which we are developing biomimetic polymeric materials for use as durable valve substitutives with native tissue, like mechanical and hydrodynamic properties.

Watch this Scientific Journal Video about Preparation of Left Ventricular Outflow Tract LVOT from Porcine Heart for Cannulation at JoVE.com

Preparation of Left Ventricular Outflow Tract (LVOT) from Porcine Heart for Cannulation   

猪心左心室流出道 （LVOT） 的制备 

首先，在心脏切除术后收集新鲜的猪心脏标本。用 Metzenbaum 剪刀解剖主动脉外的肺动脉，直到心室组织可见。然后，解剖左右冠状动脉，并在主动脉窦的起点处使用丝带结扎它们，而不会使鼻窦变窄。横断丝带远端的冠状动脉。使用 Metzenbaum 剪刀，在肺动脉瓣底部的主动脉和肺动脉之间切开右心室。从前方开始，沿脑室内隔继续沿圆周切口，以去除右心室游离壁。沿房间隔继续通过三尖瓣环向后切口，以切除所有右侧心房组织。接下来，使用 Metzenbaum 剪刀，通过平行于主动脉的右肺静脉口切开左心房。继续向二尖瓣前外侧连合切口。修剪多余的左心房组织，同时保持主动脉和二尖瓣环上三毫米的心房组织袖带。现在，通过二尖瓣的前外侧连合将切口延伸到左心室，而不会损伤前外侧肌。将脊索肌腱从前外侧肌分割到二尖瓣后瓣叶，保留与二尖瓣前叶的附着。将切口延伸到心脏的顶端。修剪肌下方多余的左心室组织，保留双侧肌。

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Research

JoVE Journal

Bioengineering

Preparation of Left Ventricular Outflow Tract (LVOT) from Porcine Heart for Cannulation 

92 Views.  Columbia University Medical Center. To begin, collect a fresh porcine cardiac specimen after cardiectomy. Dissect the pulmonary artery off the aorta with Metzenbaum scissors until ventricular tissue is visible. Then, dissect the right and the left coronary arteries, and ligate them using silk ties at their origin from the aortic sinuses without narrowing the sinuses.Transect the coronary arteries distal to the silk ties. Using Metzenbaum scissors, incise the right ventricle between the aorta and the pulmonary artery at t...

Video: Preparation of Left Ventricular Outflow Tract (LVOT) from Porcine Heart for Cannulation   

An Ex Vivo Porcine Model for Hydrodynamic Testing of Experimental Aortic Valve Procedures and Novel Medical Devices

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.

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 ...

科研

生物工程

To begin, collect a fresh porcine cardiac specimen after cardiectomy. Dissect the pulmonary artery off the aorta with Metzenbaum scissors until ventricular tissue is visible. Then, dissect the right and the left coronary arteries, and ligate them using silk ties at their origin from the aortic sinuses without narrowing the sinuses.Transect the coronary arteries distal to the silk ties. Using Metzenbaum scissors, incise the right ventricle between the aorta and the pulmonary artery at the base of the pulmonary valve. Beginning anteriorly, continue the incision circumferentially along the intraventricular septum to remove the right ventricle free wall.Continue the incision posteriorly through the tricuspid valve annulus along the interatrial septum to remove all right atrial tissue. Next, using Metzenbaum scissors, incise the left atrium through the right pulmonary vein ostium parallel to the aorta. Continue this incision towards the anterolateral commissure of the mitral valve.Trim excess left atrium tissue while maintaining the three millimeter cuff of atrial tissue on the aorta and the mitral valve annulus circumferentially. Now, extend the incision onto the left ventricle through the anterolateral commissure of the mitral valve without damaging the anterolateral papillary muscle. Divide the chordae tendineae from the anterolateral papillary muscle to the posterior mitral valve leaflet, preserving attachments to the anterior mitral valve leaflet.Extend the incision to the apex of the heart. Trim excess left ventricle tissue below the papillary muscles, preserving both papillary muscles.

Mounting a Porcine Aortic Valve on a Pulse Duplicator for Testing Hydrodynamic Properties

After preparing the left ventricular outflow tract, or LVOT, trim any excess lymphatic, connective, or pulmonary artery tissue off the aorta. Using Metzenbaum scissors, incise the superior aspect of the aortic arch from the descending aorta to the left subclavian artery. Continue the incision on the superior aspect of the aortic arch from the left subclavian artery to the brachiocephalic trunk.To cannulate the LVOT, insert the fixture into the LVOT under the anterior leaflet of the mitral valve. Wrap the left ventricle free wall around the fixture and trim excess tissue to maintain a tight wrap around the fixture. Next, remove half the thickness of the left ventricle free wall, starting at the interventricular septum.Trim one centimeter of the tissue off the superior corner of the left ventricle free wall wrap. Place the fixture in the LVOT, so the supporting rod attachment hole is one centimeter behind the left ventricle incision. Using one or two six-inch zip ties, fasten the anterior leaflet of the mitral valve to the fixture positioned between the chordae tendineae of the leaflet.Next, using a taper point needle, suture the cuff of the left atrium tissue on the aorta to the mitral valve annulus. Continue the running stitch onto the left ventricle without tearing the tissue. Using Hegar Dilators, measure the diameter of the aortic valve.Then lift the specimen by grasping the aorta to identify the neutral position of the aorta. Insert the pulse duplicator or PD fixture into the aorta, ensuring the rod attachment holes are aligned with the neutral position of the aorta. Verify the specimen's length by inserting the support rods into the attachment holes.Using one or two six-inch zip ties, secure the PD fixture to the aorta. Then using screws provided with the PD set. Secure the support rods in place.Subsequently, secure the LVOT around the PD fixture using one or two eight-inch zip ties. Place the specimen in the PD and start the hydrodynamic testing. The values for hydrodynamic testing of the native aortic valve were within the normal range with a mean regurgitation fraction of 5.74%Hydrodynamic testing values showed no significant differences between formalin and glutaraldehyde fixed samples.After the Ozaki procedure, the values obtained with the control patch material suggested consistent valve replacement outcomes.