We would like to thank Laura Janney and Abbot Medical for partial funding. We would also like to thank Duke Perfusion Services and the Large Animal Surgical Core for their assistance during the operations.

Age-matched (for blood donation if needed) calves (weight 80&#8211;90 kg) are cared for in the animal facility. Housing and all treatment procedures are performed in accordance with the guidelines of the Animal Care and Use Committee of Duke University Medical Center.
1. Initiation of Anesthesia
<ol>
	<li>After fasting for 8&#8211;12 h, pre-medicate the calf with Telazol (4.5 mg/kg/intramuscularly) and then administer isoflurane (1&#8211;4%) via a face mask.</li>
	<li>Place the cow in a supine position on a heated table and intubate. Fix the extremities to the table using heavy ties.</li>
	<li>Place an intravenous catheter (14&#8211;20 gauge) in the ear vein.</li>
	<li>Administer diazepam (0.22&#8211;0.44 mg/kg/intravenously) if chewing and swallowing are highly prevalent, or if the animal is biting on the endotracheal tube (ET) tube. Additionally, administer if there is difficulty with intubation to help facilitate airway exposure for intubation.</li>
</ol>
2. Vital Signs and Central Line Settings
<ol>
	<li>Start mechanical ventilation at a tidal volume of 10&#8211;15 mL/kg and a rate of 20&#8211;25 bpm, with isoflurane (0.5&#8211;4%) maintained throughout the procedure.</li>
	<li>Secure the ET tube using ties to ensure no changes in tube position during the operation.</li>
	<li>Continuously monitor the oxygen saturation and heart rates throughout the experiment. Address any difficulties with ventilation or oxygen saturation (SaO2) immediately. These will likely be related to either tube position, or ventilator settings. If it is tube position, adjust the ET tube to achieve adequate tidal volumes.</li>
</ol>
3. Central Vascular Access
<ol>
	<li>Although the following may be done percutaneously using ultrasound guidance, use a cut down approach to better control any local bleeding once the animal is anticoagulated.</li>
	<li>Using the trachea as a landmark, shave the neck fur (with hair clippers), and sterilize the area using betadine. Make a parallel linear incision 1&#8211;2 cm away from the trachea and 20 cm from the manubrium using a no.10 blade scalpel.</li>
	<li>Divide the sternocleidomastoid, and carefully expose the left common carotid artery and internal jugular vein using an electric cautery tool. Use a self-retaining retractor to help with the exposure. Maintain proximal and distal control of both the artery and the vein with large silk sutures (size 0 or 1 silk) or vessel loops.</li>
	<li>Cannulate the left common carotid artery with an 18-gauge catheter for blood pressure monitoring. De-air the line, and if bleeding is encountered, place a 6-0 or 7-0 polypropylene suture in a purse-string fashion around the catheter.
	<ol>
		<li>Attach the pressure transducer to the console and transduce the pressure wave into the software under &#34;systemic pressure&#34;. Read and record the output.</li>
	</ol>
	</li>
	<li>Access the left internal jugular vein for both fluid and drug administration and central venous pressure monitoring. Attach the pressure transducer to the console and transduce the pressure wave into the software under &#34;central venous pressure&#34;. Read and record the output.</li>
	<li>Secure both lines distally to the skin and monitor. Record baseline central venous pressure (CVP) and arterial blood pressure.</li>
</ol>
4. Median Sternotomy and Cardiopulmonary Bypass (CPB)
<ol>
	<li>Palpate the sternum from the manubrium to the xiphoid to choose a spot in the midline and mark using a sterile surgical marker. Shave the fur with a hair clipper, and sterilize the area using betadine. Apply a sterile surgical drape.</li>
	<li>Make an incision using a no.10 blade from the manubrium down to the xiphoid.</li>
	<li>Use an electric cautery tool to divide the pectoralis major down from the sternum, while being perfectly aligned to the midline using manual palpation of the lateral edges of the sternum. Score the midline of the sternum using the electric cautery tool. Begin the sternotomy from the bottom by dividing the xiphoid with heavy scissors.</li>
	<li>Extend the sternotomy cephalad with garden clippers. After each cut, inspect the sternum. Perform digital palpation underneath the sternum, and perform blunt dissection to help the heart and lung fall away from the sternum. Midway through the sternotomy some crossing transversalis muscle may be encountered and these are divided using electric cautery.</li>
	<li>Complete the sternotomy all the way to the manubrium. Take care to stay along the midline as this will be important for healing.</li>
	<li>After the sternotomy is completed, achieve hemostasis by scoring the bleeding muscle edges with the electric cautery tool. Apply bone wax to the marrow of the sternum to help with any residual bleeding.</li>
	<li>Identify the thymus and remove it using the electric cautery tool. Enter the pericardium in a longitudinal fashion, and reflect from the diaphragm up to the aorta.
	<ol>
		<li>Create a pericardial cradle using five 2-0 silk sutures approximating the pericardium to the skin to pull the heart up and support it. Choose all the corners of the opened pericardium and bring them directly anterior to the skin using the silk sutures.</li>
	</ol>
	</li>
	<li>Create a 3-inch-long window between the aorta and pulmonary artery by dissecting the connective tissue to allow for the passing of the aortic cross clamp. Apply a purse-string 4-0 polypropylene suture to the ascending aorta at a location proximal to the bifurcation.</li>
	<li>Circumferentially free the superior vena cava (SVC) using blunt dissection, and apply a second purse string 3-0 polypropylene suture. Establish systemic heparinization using an initial dose of 300 U/kg to achieve an activated clotting time (ACT) greater than 400 s.</li>
	<li>Once the appropriate ACT is achieved, use a no.11 blade to enter the aorta, and insert an 18 Fr arterial cannula. De-air the cannula and attach to the arterial line of CPB. Next, place a 28 Fr SVC cannula in the SVC, and start a CPB.</li>
	<li>While on partial CPB, identify the inferior vena cava (IVC) and cannulate as described for the SVC. Do so while on bypass since it allows for better hemodynamic management given the need to push on the heart for the exposure. 
	NOTE: There may still be a potential for the development of hypotension since CPB is only on as partial support at this point. If hypotension is experienced, this step should be done carefully and broken up to allow the animal&#39;s heart to fill intermittently.</li>
	<li>Once the IVC cannula is securely inserted, splice into the main circuit using a Y connector. Loop both the SVC and IVC with umbilical tape to allow for complete blood isolation from the heart.</li>
</ol>
5. Ventriculectomy
<ol>
	<li>While on full cardiopulmonary support, snare down the SVC and IVC using the previously applied umbilical tape. Apply an aortic cross clamp proximal to the aortic cannulation site. Once the clamp position has been confirmed, start the ventriculectomy.</li>
	<li>Excise the ventricular tissue circumferentially 1-2 cm distal to the right and left atrioventricular groove. Leave the rim of ventricular muscle with the mitral and tricuspid annuli to provide further support for the implantation of the swing rings.</li>
	<li>Transect the sub-valvular apparati for the mitral and tricuspid valves as they are encountered.</li>
	<li>Excise the right ventricle outflow tract muscle with the right ventricular outflow tract (RVOT) including the excision of the pulmonary valve. Also, excise the left ventricular outflow tract (LVOT), but preserve the posterior aspect of the aortic valve as part of the aorto-mitral curtain.</li>
	<li>Divide the interventricular septum last. Identify the orifice of the coronary sinus and ligate with 5-0 polypropylene sutures.</li>
</ol>
6. Implantation of Centrifugal Flow Pumps (CFP)
<ol>
	<li>Use pledgeted, interrupted, 2-0 braided sutures to secure the sewing ring to the ventricular tissue and mitral valve annulus. Exit the sutures on the epicardial surface of the ventricular muscle rim and bring through the sewing ring. This technique avoids &#34;bunching up&#34; of the tissue above the ring which would interfere with the coaptation of the ring with the pump.</li>
	<li>Use a similar approach to attach the sewing ring to the right ventricle muscle rim and tricuspid annulus.</li>
	<li>Attach the CFPs to the sewing rings and secure with the standard locking mechanism. Orient these to allow access to the locking mechanism.</li>
	<li>Adjust the outflow graft length according to the orientation of choice. Once a proper length has been identified, cut the outflow graft. Take care to not make the graft too long as that may cause kinking.</li>
	<li>Use running 4-0 polypropylene sutures to anastomose the outflow grafts to the aorta (for the left heart CFP) and pulmonary artery (for the right heart CFP) in an end to end fashion.</li>
	<li>Prior to completing the anastomoses, release the tape on the SVC and IVC drainage cannulas and allow blood to fill the right and left pump, thus beginning the de-airing process. Place an 18-gauge needle into each of the outflow grafts for further de-airing. Use the ventilator to provide large volume breaths to allow for any air trapped in the pulmonary veins to be returned and de-aired.
	<ol>
		<li>After de-airing is complete, remove the needle, and repair the site using pledgeted 5-0 polypropylene sutures.</li>
	</ol>
	</li>
	<li>Start the pumps at a low rpm speed (3,000 rpm) to allow for forward blood flow, initially with the clamp still in place. Remove the aortic cross clamp and leave some blood volume to enter the pumps.</li>
	<li>Gradually increase the pump speed as the cardiopulmonary support is weaned. Terminate the CPB and support the circulation entirely by the right and left side pumps.</li>
	<li>Determine the final pump speed settings by the venous filling pressures on the right and left side.</li>
	<li>Introduce pressure catheters directly into the pulmonary artery and the pulmonary veins using a purse-string 5-0 polypropylene suture to secure them in place.</li>
	<li>Transduce pressure signals to the software under the labels &#34;pulmonary artery&#34; and &#34;pulmonary vein&#34;. In addition, place ultrasonic flow probes around the ascending aorta and the main pulmonary artery. 
	NOTE: All 4 channels should now be active: 1. &#34;systemic pressure&#34;, 2. &#34;central venous pressure&#34;, 3. &#34;pulmonary artery&#34; and 4. &#34;pulmonary vein&#34;.</li>
</ol>
7. Establishment of Biventricular Assist Device Flow
<ol>
	<li>While gradually decreasing the CPB flow, slowly increase the left CFP and then the right CFP speed while always maintaining a lower right CFP speed than the left CFP.</li>
	<li>Pay careful attention to the hemodynamics, including the systemic blood pressure and CVP. Pulmonary overcirculation is indicated by non-physiological pressures in the pulmonary artery or pulmonary vein.</li>
	<li>Eventually, increase the left CFP and right CFP speeds to achieve a flow of 4 L/min on each device and wean off the CPB. Once hemodynamic stability is achieved, remove the SVC and IVC cannulas and tie down the purse-string sutures.</li>
	<li>Next, remove the aortic cannula and tie down the purse-string suture. Euthanize the animal by slowly turning down, and then stopping both the CFP pumps while the animal is under anesthesia.</li>
</ol>

<ol>
	<li>Mozzafarian, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+disease+and+stroke+statistics&#8212;2016+update:+a+report+from+the+American+Heart+Association.">Heart disease and stroke statistics&#8212;2016 update: a report from the American Heart Association.</a> Circulation. 133 (4), e38-e360 (2016).</li><li>Slaughter, M. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advanced+heart+failure+treated+with+continuous-flow+left+ventricular+assist+device.">Advanced heart failure treated with continuous-flow left ventricular assist device.</a> N Engl J Med. 361 (23), 2241-2251 (2009).</li><li>Fang, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rise+of+the+Machines+&#8212;+Left+Ventricular+Assist+Devices+as+Permanent+Therapy+for+Advanced+Heart+Failure.">Rise of the Machines &#8212; Left Ventricular Assist Devices as Permanent Therapy for Advanced Heart Failure.</a> N Engl J Med. 361, 2282-2285 (2009).</li><li>Kirklin, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seventh+INTERMACS+annual+report:+15,000+patients+and+counting.">Seventh INTERMACS annual report: 15,000 patients and counting.</a> J Heart Lung Transplant. 34 (12), 1495-1504 (2015).</li><li>Leidenfrost, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Right+ventricular+assist+device+with+membrane+oxygenator+support+for+right+ventricular+failure+following+implantable+left+ventricular+assist+device+placement.">Right ventricular assist device with membrane oxygenator support for right ventricular failure following implantable left ventricular assist device placement.</a> Eur J Cardiothorac Surg. 49 (1), 73-77 (2016).</li><li>Gerosa, G., Gallo, M., Bottio, T., Tarzia, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Successful+heart+transplant+after+1374+days+living+with+a+total+artificial+heart.">Successful heart transplant after 1374 days living with a total artificial heart.</a> Eur J Cardiothorac Surg. 49 (4), e88-e89 (2016).</li><li>Pelletier, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=System+overview+of+the+fully+implantable+destination+therapy--ReinHeart-total+artificial+heart.">System overview of the fully implantable destination therapy--ReinHeart-total artificial heart.</a> Eur J Cardiothorac Surg. 47 (1), 80-86 (2015).</li><li>Krabatsch, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biventricular+circulatory+support+with+two+miniaturized+implantable+assist+devices.">Biventricular circulatory support with two miniaturized implantable assist devices.</a> Circulation. 124, S179-S186 (2011).</li><li>Milano, C. A., Schroder, J., Daneshmand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Total+Artificial+Heart+Replacement+With+2+Centrifugal+Blood+Pumps.">Total Artificial Heart Replacement With 2 Centrifugal Blood Pumps.</a> Oper Tech Thorac Cardiovasc Surg. 20 (3), 306-321 (2016).</li><li>Strueber, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Placement+of+2+implantable+centrifugal+pumps+to+serve+as+a+total+artificial+heart+after+cardiectomy.">Placement of 2 implantable centrifugal pumps to serve as a total artificial heart after cardiectomy.</a> J Thorac Cardiovasc Surg. 143 (2), 507-509 (2012).</li></ol>

This work was made possible through a research grant from Abbot Medical to Dr. Milano.

In this manuscript, we describe the use of two centrifugal flow VADs as an intracorporeal TAH. This technique maybe very useful to study the effect of artificial circulation on secondary organs such as the lungs and liver. Furthermore, it may be useful for the study of the hemodynamic changes from different pump orientations and flow scenarios. The critical steps within this protocol involve how the sewing rings are attached to the ventricular tissue while also incorporating the valvular annuli for strength. It is crucial to ensure that this is performed correctly as it will affect device stability. Furthermore, it is important to ensure that the outflow grafts are measured and cut at the appropriate length. Device instability and outflow graft obstruction represent important problems that may occur if these two steps are not carefully performed.
The protocol describes two different methods of orienting the outflow grafts that may be important to avoid outflow graft obstruction. In the first orientation, the outflow grafts are connected directly to the respective great vessels in an orientation similar to the SynCardia Total Artificial Heart. In the second orientation, the grafts rotate around the other VAD as is commonly employed in clinical VAD cases.
Using this experimental model, one can carefully study the hemodynamic scenarios associated with different combinations of pump speeds, to determine how to avoid the imbalance of left and right sided circulations. For instance, the direct measurements of aortic, pulmonary artery and pulmonary vein pressures allow for a real-time assessment of the overall hemodynamic status of the animal. This will be quite important for setting the correct speed parameters on the pumps to allow for balanced right and left circulations with: adequate arterial perfusion pressure; normal pulmonary pressures to avoid the possibility of pulmonary congestion; and normal central venous pressures to avoid renal or hepatic venous congestion. In the clinically available devices, &#34;flow&#34; is a calculated parameter which is not directly measured. In this protocol, we will directly measure flow in two locations for further precise assessment of the hemodynamics.
In conclusion, this manuscript describes the use of two centrifugal flow pumps as a total artificial heart for intracorporeal biventricular replacement in a cow model.

There has been growth in the number of patients with heart failure, with an estimated 5.7 million adults suffering from this condition in the United States today1. Around 300,000 patients have end stage heart failure with a life expectancy of less than one year. While heart transplantation remains the gold standard therapy for end stage heart failure, it is greatly limited by the number of available donor organs. MCS has been introduced as a viable alternative to heart transplantation especially through the use of VADs2. VADs work by unloading the left ventricle and providing forward flow (supported by a pump) directly into the arterial circulation. VADs may be implanted as a bridge to transplantation as well as a destination therapy for patients that do not qualify for a transplantation3. Since their FDA approval less than a decade ago, the annual number of VADs implanted has surpassed heart transplant numbers, with this number exponentially increasing4. However, in a subset of patients, heart failure is biventricular (i.e. affecting both the left and right ventricle) and simply supporting the left ventricle alone may not provide adequate perfusion. In these situations, the right ventricle requires temporary mechanical support5. This type of &#34;RVAD&#34; requires the use of large cannulas connected to an extracorporeal pump that restricts the patient to the Intensive Care Unit (ICU) while the ventricle recovers. For a limited subset of patients, another option is a TAH6,7. The indications for TAH usage are: a biventricular failure after post infarct, a ventricle septal defect (VSD), a severe restrictive myopathy which precludes ventricular cannulation, and a failed heart transplant requiring chronic support. However, the currently FDA approved TAH device is large and cannot be used in smaller patients. In addition, the pneumatic drivers are sizable and limit the mobility of the patient.
One experimental strategy for some patients is the use of a second VAD to support the right ventricle8,9,10. In this scenario, both ventricles are excised, and two VADs are implanted as a TAH. This has been made possible by the improvements in device design and the shrinking of the device profile. New centrifugal VADs are much smaller, allowing for two VADs to be implanted next to each other to support both the left and right circulation. This approach remains experimental with many important challenges including the device settings to balance the right and left circulation, the orientation of the devices and outflow graft with their influence on hemolysis and other adverse events. The purpose of this protocol is to provide a reproducible approach to TAH replacement with two centrifugal VADs in a cow model.

<table border="0" cellpadding="0" cellspacing="0" width="699">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">SPO2&#160; and heart rates are to be monitored: Multiparameter</td>
			<td style="width:148px;">Meditech Equipment, Co., Ltd.</td>
			<td style="width:168px;">MD-908</td>
			<td style="width:167px;">hemodynamic monitor intraoperatively</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Viscot Mini XL Surgical Markers</td>
			<td style="width:148px;">Amazon</td>
			<td style="width:168px;">B007P550WG</td>
			<td style="width:167px;">marking sternum before incision</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">60W High Power Electric Pet Cat Rabbits Horse Animal Hair Cutting Clipper</td>
			<td style="width:148px;">LILY International Business CO., LIMITED&#160;</td>
			<td style="width:168px;">ZP-293</td>
			<td>Fur shaving</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">No. 10 scalpel blade</td>
			<td style="width:148px;">Swann-Mortan, England</td>
			<td align="right" style="width:168px;">301</td>
			<td>Skin incision</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Matzenbaum scissor</td>
			<td style="width:148px;">BD-V. Mueller, USA</td>
			<td style="width:168px;">CH2006-001</td>
			<td>Vascular exploration</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Scissors</td>
			<td style="width:148px;">Felco, USA</td>
			<td style="width:168px;">FELCO 200A-50, Felco Professional Bypass Lopper</td>
			<td style="width:167px;">For sternotomy</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">A self-retractor</td>
			<td style="width:148px;">BD-V. Mueller, USA</td>
			<td style="width:168px;">AU19270</td>
			<td style="width:167px;">SCHUKNECHT Self-Retaining Postauricular Retractor,&#160;</td>
		</tr>
		<tr height="46">
			<td height="46" style="height:46px;width:216px;">Sternal retractor</td>
			<td style="width:148px;">BD-V. Mueller, USA</td>
			<td style="width:168px;">CH6950-007</td>
			<td style="width:167px;">Cooley sternal retractor</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Pressure transducer (Millar Mikro-Tip, 5Fr)</td>
			<td style="width:148px;">Millar, USA</td>
			<td style="width:168px;">MillarMikro-Tip, SPR-350S</td>
			<td style="width:167px;">Assessment for pulmonary artery or venous pressure</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">AD instruments (PowerLab)</td>
			<td style="width:148px;">AD instruments, USA</td>
			<td style="width:168px;">PowerLab 16/35</td>
			<td style="width:167px;">Pressure signal transduction</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Umbilical tapes</td>
			<td style="width:148px;">Medline industries Inc., USA</td>
			<td style="width:168px;">U11</td>
			<td style="width:167px;">For isolation and snaring of superior or inferior vena cava</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Vessel loops</td>
			<td style="width:148px;">Aspen Surgical, USA</td>
			<td style="width:168px;">3901, 3902 and 3904</td>
			<td style="width:167px;">Isolation of vessels</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Silk sutures, 2-0</td>
			<td style="width:148px;">Ethicon US, LLC, USA</td>
			<td style="width:168px;">SA11G</td>
			<td style="width:167px;">For snare of superior or inferior vena cava</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ticron 2-0</td>
			<td style="width:148px;">Covidien, USA</td>
			<td style="width:168px;">TicronTM suture</td>
			<td style="width:167px;">Vascular suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Prolene, 7-0</td>
			<td style="width:148px;">Covidien, USA</td>
			<td style="width:168px;">Surgipro II</td>
			<td style="width:167px;">Vascular suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Prolene, 6-0</td>
			<td style="width:148px;">Covidien, USA</td>
			<td style="width:168px;">Surgipro II</td>
			<td style="width:167px;">Vascular suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Prolene, 4-0</td>
			<td style="width:148px;">Covidien, USA</td>
			<td style="width:168px;">Surgipro II</td>
			<td style="width:167px;">Vascular suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Prolene, 3-0</td>
			<td style="width:148px;">Covidien, USA</td>
			<td style="width:168px;">Surgipro II</td>
			<td style="width:167px;">Vascular suture</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Aortic cannula, 15-18 Fr</td>
			<td style="width:148px;">Medtronic, USA</td>
			<td style="width:168px;">Elongated-One-Piece-Arterial cannula 3D</td>
			<td style="width:167px;">Aortic cannula for setting of cardiopulmonary bypass</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Venous cannula, 28Fr</td>
			<td style="width:148px;">Edwards Lifesciences</td>
			<td style="width:168px;">single stage</td>
			<td style="width:167px;">Venous cannula for setting of cardiopulmonary bypass</td>
		</tr>
	</tbody>
</table>

use of two intracorporeal ventricular assist devices as a total artificial heart

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ventricular assist devices (VADs) for support of the left ventricle. However, certain clinical scenarios warrant biventricular mechanical support. One strategy for some patients is the excision of both ventricles and the implantation of two VAD pumps as a total artificial heart (TAH). This has recently been made possible by the improvements in device design and the small profile of centrifugal devices. This TAH approach remains experimental with many important challenges such as the device settings to balance the right and left circulation, the orientation of the devices and the outflow graft with their influence on hemolysis and stability, and the outcome of chronic support using such an orientation. This protocol aims to provide a reproducible approach for total artificial heart replacement with two intracorporeal centrifugal VADs in a cow model.

Demonstrated in Figure 1 is the attachment of the sewing rings. Figure 1A shows the &#34;bunching&#34; of the ventricle tissue that may create a problem with pump attachment. Figure 1B represents the correct attachment.
Figure 2 and Figure 3 are two different orientations of the pumps. In Figure 2, the pumps are positioned so that the outflow grafts are short and exit directly into the connected arteries. In Figure 3, the pumps are oriented so that the outflow grafts of both the right CFP and left CFP rotate around prior to being anastomosed to the pulmonary artery and aorta, respectively. It remains unanswered which orientation allows for less sheer stress on the blood, and has better overall hemodynamic profile for the pump. Furthermore, it is unclear which orientation allows for less kinking.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55961/55961fig1.jpg" /> 
Figure 1: Attachment of the sewing rings. 
Panel A demonstrates incorrect attachment of the right heart replacement sewing ring with the &#34;bunched up&#34; ventricular tissue. Panel B demonstrates the correct sewing ring incorporation into the ventricular tissue. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55961/55961fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55961/55961fig2.jpg" /> 
Figure 2: Direct outflow graft orientation demonstrating direct attachment of the right heart replacement to the pulmonary artery and the left heart replacement to the aorta. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55961/55961fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/55961/55961fig3.jpg" /> 
Figure 3: A different orientation of the outflow grafts to the pulmonary artery and the aorta. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55961/55961fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart at JoVE.com

Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart

Here, we present a protocol using two centrifugal pumps as a total artificial heart replacement.

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ...

use-two-intracorporeal-ventricular-assist-devices-as-total-artificial

Nanyang Technological University

Research

JoVE Journal

Medicine

9.3K Views.  Duke University. Here, we present a protocol using two centrifugal pumps as a total artificial heart replacement.

Video: Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart

Reverse Total Shoulder Arthroplasty

Reverse total shoulder arthroplasty was initially approved for use in rotator cuff arthropathy and well as chronic pseudoparalysis without arthritis in patients who were not appropriate for tendon transfer reconstructions. Traditional surgical options for these patients were limited and functional results were sub-optimal and at times catastrophic. The use of reverse shoulder arthroplasty has been found to effectively restore these patients function and relieve symptoms associated with their disease. The procedure can be done through two approaches, the deltopectoral or the superolateral. Complication rates associated with the use of the prosthesis have ranged from 8-60% with more recent reports trending lower as experienced is gained. Salvage options for a failed reverse shoulder prosthesis are limited and often have significant associated disability. Indications for the use of this prosthesis continue to be evaluated including its use for revision arthroplasty, proximal humeral fracture and tumor. Careful patient selection is essential because of the significant risks associated with the procedure.

Reverse total shoulder arthroplasty is indicated for the treatment of conditions that cannot be treated with conventional arthroplasty or other procedures. These primarily include degenerative and incapacitating conditions with irreparable rotator cuff and loss of the normal biomechanical coupling of the shoulder.

Reverse total shoulder arthroplasty was initially approved for use in rotator cuff arthropathy and well as chronic pseudoparalysis without arthritis in ...

A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and  Ease of Implantation

Implantable cardioverter-defibrillators (ICDs) terminate ventricular tachycardia (VT) and ventricular fibrillation (VF) with high efficacy and can protect patients from sudden cardiac death (SCD). However, inappropriate shocks may occur if tachycardias are misdiagnosed. Inappropriate shocks are harmful and impair patient quality of life. The risk of inappropriate therapy increases with lower detection rates programmed in the ICD. Single-chamber detection poses greater risks for misdiagnosis when compared with dual-chamber devices that have the benefit of additional atrial information. However, using a dual-chamber device merely for the sake of detection is generally not accepted, since the risks associated with the second electrode may outweigh the benefits of detection. Therefore, BIOTRONIK developed a ventricular lead called the LinoxSMART S DX, which allows for the detection of atrial signals from two electrodes positioned at the atrial part of the ventricular electrode. This device contains two ring electrodes; one that contacts the atrial wall at the junction of the superior vena cava (SVC) and one positioned at the free floating part of the electrode in the atrium. The excellent signal quality can only be achieved by a special filter setting in the ICD (Lumax 540 and 740 VR-T DX, BIOTRONIK). Here, the ease of implantation of the system will be demonstrated.

Dual-chamber implantable cardioverter-defibrillators (ICDs) may improve detection of atrial fibrillation as well as differentiation of tachycardias. However, this advantage is undermined by complications associated with the second electrode, which is required in conventional dual chamber devices. Therefore, BIOTRONIK has developed a new electrode called the LinoxSMART S DX that, when used in conjunction with the Lumax DX ICD, offers dual-chamber detection without the risks associated with the second electrode.

Implantable cardioverter-defibrillators (ICDs) terminate ventricular tachycardia (VT) and ventricular fibrillation (VF) with high efficacy and can protect ...

Reduction in Left Ventricular Wall Stress and Improvement in Function in Failing Hearts using Algisyl-LVR

Injection of Algisyl-LVR, a treatment under clinical development, is intended to treat patients with dilated cardiomyopathy. This treatment was recently used for the first time in patients who had symptomatic heart failure. In all patients, cardiac function of the left ventricle (LV) improved significantly, as manifested by consistent reduction of the LV volume and wall stress. Here we describe this novel treatment procedure and the methods used to quantify its effects on LV wall stress and function.
Algisyl-LVR is a biopolymer gel consisting of Na+-Alginate and Ca2+-Alginate. The treatment procedure was carried out by mixing these two components and then combining them into one syringe for intramyocardial injections. This mixture was injected at 10 to 19 locations mid-way between the base and apex of the LV free wall in patients.
Magnetic resonance imaging (MRI), together with mathematical modeling, was used to quantify the effects of this treatment in patients before treatment and at various time points during recovery. The epicardial and endocardial surfaces were first digitized from the MR images to reconstruct the LV geometry at end-systole and at end-diastole. Left ventricular cavity volumes were then measured from these reconstructed surfaces.
Mathematical models of the LV were created from these MRI-reconstructed surfaces to calculate regional myofiber stress. Each LV model was constructed so that 1) it deforms according to a previously validated stress-strain relationship of the myocardium, and 2) the predicted LV cavity volume from these models matches the corresponding MRI-measured volume at end-diastole and end-systole. Diastolic filling was simulated by loading the LV endocardial surface with a prescribed end-diastolic pressure. Systolic contraction was simulated by concurrently loading the endocardial surface with a prescribed end-systolic pressure and adding active contraction in the myofiber direction. Regional myofiber stress at end-diastole and end-systole was computed from the deformed LV based on the stress-strain relationship.

This article describes procedures for implanting a novel hydrogel in failing hearts and quantifying its effect on left ventricular wall stress and function. These procedures have been successfully applied in dogs and humans.

Injection of  Algisyl-LVR, a treatment under clinical development, is intended to treat  patients with dilated cardiomyopathy. This treatment was recently ...

Development of an Audio-based Virtual Gaming Environment to Assist with Navigation Skills in the Blind

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio ...

Implantation of the Syncardia Total Artificial Heart

With advances in technology, the use of mechanical circulatory support devices for end stage heart failure has rapidly increased. The vast majority of such patients are generally well served by left ventricular assist devices (LVADs). However, a subset of patients with late stage biventricular failure or other significant anatomic lesions are not adequately treated by isolated left ventricular mechanical support. Examples of concomitant cardiac pathology that may be better treated by resection and TAH replacement includes: post infarction ventricular septal defect,&#160;aortic root aneurysm / dissection, cardiac allograft failure, massive ventricular thrombus, refractory malignant arrhythmias (independent of filling pressures), hypertrophic / restrictive cardiomyopathy, and complex congenital heart disease. Patients often present with cardiogenic shock and multi system organ dysfunction. Excision of both ventricles and orthotopic replacement with a total artificial heart (TAH) is an effective, albeit extreme, therapy for rapid restoration of blood flow and resuscitation. Perioperative management is focused on end organ resuscitation and physical rehabilitation. In addition to the usual concerns of infection, bleeding, and thromboembolism common to all mechanically supported patients, TAH patients face unique risks with regard to renal failure and anemia. Supplementation of the abrupt decrease in brain natriuretic peptide following ventriculectomy appears to have protective renal effects. Anemia following TAH implantation can be profound and persistent. Nonetheless, the anemia is generally well tolerated and transfusion are limited to avoid HLA sensitization. Until recently, TAH patients were confined as inpatients tethered to a 500 lb pneumatic console driver. Recent introduction of a backpack sized portable driver (currently under clinical trial) has enabled patients to be discharged home and even return to work. Despite the profound presentation of these sick patients, there is a 79-87% success in bridge to transplantation.

The purpose of this manuscript is to briefly review indications, management, and outcomes for the total artificial heart. Video operative techniques for device implantation are presented.

With advances in technology, the use of mechanical circulatory support devices for end stage heart failure has rapidly increased. The vast majority of ...

Implantation of Total Artificial Heart in Congenital Heart Disease

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. 
In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. 
Due to the patient's grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient's ventricles and great arteries required modifications to the TAH during implantation.
With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification.

This is a case report of a patient with congenitally corrected transposition of the great arteries (CCTGA) who received a total artificial heart (TAH) as a bridge to heart transplant. The TAH was successfully implanted with modifications to accommodate the patient's congenitally malformed heart.

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital ...

An Isolated Working Heart System for Large Animal Models

Since its introduction in the late 19th century, the Langendorff isolated heart perfusion apparatus, and the subsequent development of the working heart model, have been invaluable tools for studying cardiovascular function and disease1-15. Although the Langendorff heart preparation can be used for any mammalian heart, most studies involving this apparatus use small animal models (e.g., mouse, rat, and rabbit) due to the increased complexity of systems for larger mammals1,3,11. One major difficulty is ensuring a constant coronary perfusion pressure over a range of different heart sizes &#8211; a key component of any experiment utilizing this device1,11. By replacing the classic hydrostatic afterload column with a centrifugal pump, the Langendorff working heart apparatus described below allows for easy adjustment and tight regulation of perfusion pressures, meaning the same set-up can be used for various species or heart sizes. Furthermore, this configuration can also seamlessly switch between constant pressure or constant flow during reperfusion, depending on the user&#8217;s preferences. The open nature of this setup, despite making temperature regulation more difficult than other designs, allows for easy collection of effluent and ventricular pressure-volume data.

Most studies involving the Langendorff apparatus use small animal models due to the increased complexity of systems for larger mammals. We describe a Langendorff system for large animal models that allows for use across a range of species, including humans, and relatively easy data acquisition.

Since its introduction in the late 19th century, the Langendorff isolated heart perfusion apparatus, and the subsequent development of the working heart ...

Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies

Murine cardiomyocytes have been extensively used for in vitro studies of cardiac physiology and new therapeutic strategies. However, multicellular preparations of dissociated cardiomyocytes are not representative of the complex in vivo structure of cardiomyocytes, non-myocytes and extracellular matrix, which influences both mechanical and electrophysiological properties of the heart. Here we describe a technique to prepare viable ventricular slices of adult mouse hearts with a preserved in vivo like tissue structure, and demonstrate their suitability for electrophysiological recordings. After excision of the heart, ventricles are separated from the atria, perfused with Ca2+-free solution containing 2,3-butanedione monoxime and embedded in a 4% low-melt agarose block. The block is placed on a microtome with a vibrating blade, and tissue slices with a thickness of 150-400 &#181;m are prepared keeping the vibration frequency of the blade at 60-70 Hz and moving the blade forward as slowly as possible. Thickness of the slices depends on the further application. Slices are stored in ice cold Tyrode&#39;s solution with 0.9 mM Ca2+ and 2,3-butanedione monoxime (BDM) for 30 min. Afterwards, slices are transferred to 37 &#176;C DMEM for 30 min to wash out the BDM. Slices can be used for electrophysiological studies with sharp electrodes or micro electrode arrays, for force measurements to analyze contractile function or to investigate the interaction of transplanted stem cell-derived cardiomyocytes and host tissue. For sharp electrode recordings, a slice is placed into a 3 cm cell culture dish on the heating plate of an inverted microscope. The slice is stimulated with a unipolar electrode, and intracellular action potentials of cardiomyocytes within the slice are recorded with a sharp glass electrode.

Here, we describe the preparation of viable ventricular slices from adult mice and their use for sharp electrode action potential recordings. These multicellular preparations provide a preserved in vivo like tissue structure, which makes them a valuable model for electrophysiological and pharmacological studies in vitro.

Murine cardiomyocytes have been extensively used for in vitro studies of cardiac physiology and new therapeutic strategies. However, multicellular ...

Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment methods. Here, we present such a model by tachycardia-induced cardiomyopathy, which can be produced by rapid cardiac pacing in swine.
A single pacing lead is introduced transvenously into fully anaesthetized healthy swine, to the apex of the right ventricle, and fixated. Its other end is then tunneled dorsally to the paravertebral region. There, it is connected to an in-house modified heart pacemaker unit that is then implanted in a subcutaneous pocket. 
After 4 - 8 weeks of rapid ventricular pacing at rates of 200 - 240 beats/min, physical examination revealed signs of severe heart failure - tachypnea, spontaneous sinus tachycardia, and fatigue. Echocardiography and X-ray showed dilation of all heart chambers, effusions, and severe systolic dysfunction. These findings correspond well to decompensated dilated cardiomyopathy and are also preserved after the cessation of pacing.
This model of tachycardia-induced cardiomyopathy can be used for studying the pathophysiology of progressive chronic heart failure, especially hemodynamic changes caused by new treatment modalities like mechanical circulatory supports. This methodology is easy to perform and the results are robust and reproducible.

Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment ...

Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo

Because of their critical role in regulating immune responses, macrophages have continuously been the subject of intensive research and represent a promising therapeutic target in many disorders, such as autoimmune diseases, atherosclerosis, and cancer. RNAi-mediated gene silencing is a valuable approach of choice to probe and manipulate macrophage function; however, the transfection of macrophages with siRNA is often considered to be technically challenging, and, at present, few methodologies dedicated to the siRNA transfer to macrophages are available. Here, we present a protocol of using polyethyleneimine-coated superparamagnetic iron oxide nanoparticles (PEI-SPIONs) as a vehicle for the targeted delivery of siRNA to macrophages. PEI-SPIONs are capable of binding and completely condensing siRNA when the Fe:siRNA weight ratio reaches 4 and above. In vitro, these nanoparticles can efficiently deliver siRNA into primary macrophages, as well as into the macrophage-like RAW 264.7 cell line, without compromising cell viability at the optimal dose for transfection, and, ultimately, they induce siRNA-mediated target gene silencing. Apart from being used for in vitro siRNA transfection, PEI-SPIONs are also a promising tool for delivering siRNA to macrophages in vivo. In view of its combined features of magnetic property and gene-silencing ability, systemically administered PEI-SPION/siRNA particles are expected not only to modulate macrophage function but also to enable macrophages to be imaged and tracked. In essence, PEI-SPIONs represent a simple, safe, and effective nonviral platform for siRNA delivery to macrophages both in vitro and in vivo.

Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo

We describe a method of using polyethyleneimine (PEI)-coated superparamagnetic iron oxide nanoparticles for transfecting macrophages with siRNA. These nanoparticles can efficiently deliver siRNA to macrophages in vitro and in vivo and silence target gene expression.

Because of their critical role in regulating immune responses, macrophages have continuously been the subject of intensive research and represent a ...