To the TandemHeart team at&#160;LifeSparc.

This procedure and protocol have been approved by the institutional review board and the United States Food and Drug Administration (FDA).
1. Patient criteria
<ol>
	<li>Include patients with CS stage B and above as defined by the SCAI consensus statement1.</li>
	<li>Include as bridge to transplant or durable left ventricular assist system in stage D heart failure.</li>
	<li>Include as bridge to recovery in AMI complicated by CS.</li>
	<li>Exclude contra-indication to systemic anticoagulation.</li>
	<li>Exclude life-expectancy &#60;6 months (active malignancy).</li>
	<li>Exclude if there is the presence of LA thrombus.</li>
	<li>Exclude if patients have peripheral vascular disease (PVD) with small arteries that cannot accommodate the large cannulas.</li>
	<li>Exclude if patients have an irreversible neurological injury/coma.</li>
	<li>Exclude if patients have severe aortic insufficiency (AI).</li>
	<li>Exclude if patients have a ventricular septal defect (VSD). 
	NOTE: The placement of the LAFAB device includes three separate processes: 1) setting up the controller and the pump; 2) placement of arterial and venous cannulas and transeptal access under transesophageal echocardiogram (TEE) or intracardiac echocardiogram (ICE); and 3) connecting the system to the circuit.</li>
</ol>
2. Placement of the left atrium to femoral artery bypass device
<ol>
	<li>Setting up the controller 
	NOTE: This step can be performed as the patient is being transported to the lab and the table is being set up for the procedure. Usually, the device representative and perfusionist team is present to assist with the process.
	<ol>
		<li>Open the box and initiate the controller setup with the following steps.</li>
		<li>Prior to powering on the controller, place 2 batteries in the controller by opening the battery door. Insert each battery by placing the logo facing away from the controller screen. The groove on the battery should align with the key battery housing. Make sure that the batteries are well seated.</li>
		<li>Install the other 2 batteries in the dock following the same process.</li>
		<li>Attach the controller to the dock, verify it is fully seated on the dock and connect the power cord to the power outlet and plug it in to the wall socket for AC power. The controller can operate in the dock connected to AC power or when separated from the dock, it can operate using battery power.</li>
		<li>Mount the dock and controller on an intravenous pole using the clamp.</li>
		<li>Turn on the controller using the buttons on the side.</li>
	</ol>
	</li>
	<li>Setting up the pump &#8211; Priming the system 
	NOTE: Pump priming requires two people &#8212; the primary operator is scrubbed (sterile operator) and stays in the sterile field. The secondary operator (non-sterile operator) handles the controller in the non-sterile field. Pump de-airing is a crucial step and needs to be performed very carefully.
	<ol>
		<li>Have the secondary operator open the package and present the priming tray to the primary operator. Have the primary operator then open the sterile drape and lay out the components of the priming tray on the sterile table. The pump, oxygenator and green oxygen tubing are included in the tray.</li>
		<li>Have the primary operator hand the pump driveline to the secondary operator who then plugs it to the controller.</li>
		<li>Have the sterile operator remove the protective caps on the tubing and inserts the ends to the basin. The blue tubing is the inflow tubing which goes into the blue port. The red tubing is the outflow tubing which goes into the red port of the basin.</li>
		<li>Place the basin in the fill ready position tilted back and away from the blue port.</li>
		<li>Have the secondary operator fill the basin with 4 liters of saline.</li>
		<li>Have the primary operator lift the basin and tilt it back to prime ready position to gravity prime the pump.</li>
		<li>Make sure that all the air has been removed from the tubing and the pump. Gently tap the tubing and the pump to remove any small air bubbles. This is a crucial step.</li>
		<li>Then turn on the pump from the non-sterile end.</li>
		<li>Remove any tiny air bubbles in the oxygenator by gently tapping the oxygenator and positioning the outflow tubing at a higher level (12 o&#8217;clock position) for the air bubbles to rise above and escape out.</li>
		<li>Stop the pump once all the air bubbles are removed.</li>
		<li>Clamp the inflow and outflow tubing. Remove the inflow and outflow tubing from the basin and then attach the green oxygen supply tubing to the gas in port on the oxygenator. The circuit is now ready.</li>
	</ol>
	</li>
	<li>Transseptal access10,32 &#160;
	<ol>
		<li>Prepare and drape the patient in a sterile manner.</li>
		<li>Perform the procedure under general anesthesia with the anesthesia team.</li>
		<li>Once the patient is intubated and sedated adequately, pass the TEE probe into the esophagus and obtain the basic images. If using ICE, then obtain the images after venous access.</li>
		<li>Identify the ideal spot for septostomy on the inter-atrial septum (IAS) using TEE or ICE. Use the bicaval view on TEE showing the membranous part of the IAS at the region of the fossa ovalis to expose the IAS better.</li>
		<li>Confirm the absence of any thrombus in the LA where the inflow cannula will be positioned using TEE or ICE.</li>
		<li>Obtain femoral venous access via ultrasound guidance with modified Seldinger technique and insert an 0.035&#8221; guidewire</li>
		<li>Advance the guidewire to the inferior vena cava (IVC) &#8211; right atrial junction and then direct it towards the IAS under fluoroscopic and TEE or ICE guidance. Using multiple angiographic projections (Right or Left Anterior Oblique), identify the optimal site for transeptal puncture. Ideally, it should be done in the region of the foramen ovale to minimize complications.&#160; In patients with thick or aneurysmal septa or an IAS which has been previously patched or instrumented surgically or closed percutaneously, one may consider use of an energized or radiofrequency transseptal needle to insure precise puncture without needle deflection.</li>
		<li>Anticoagulate the patient (ACT more than 250 seconds). Perform transseptal puncture using a transseptal needle, insert guidewire to the LA.</li>
		<li>Dilate the venous access and the IAS with a 2-stage dilator. Insert the transseptal cannula and advance it into LA, remove introducer and guidewire, wait for back-bleed, and clamp. Secure cannula to the patient.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/62140/62140fig2v2.jpg" /> 
Figure 2: TEE with biplane in the bicaval view showing the SVC to the right, the interatrial septum horizontal in the middle with the left atrium above and the right atrium below, and the IVC towards the left. (A) - Guidewire passing into the SVC. (B) - Sheath passing over the wire into the SVC. (C) - Transseptal needle passing through the sheath. (D) - Transseptal needle tenting the interatrial septum. (E) - Sheath passing through the interatrial septum into the left atrium, after the needle has been withdrawn. Picture courtesy47&#160; 
SVC &#8211; Superior Vena Cava, IVC &#8211; Inferior Vena Cava, RA &#8211; Right Atrium, LA &#8211; Left Atrium&#160;
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/62140/62140fig3v2.jpg" /> 
Figure 3:&#160;ICE for transeptal access ICE guided trans septal access showing inter-atrial septum and fossa ovalis (FO) in (A), septal tenting as the needle engages in (B), loss of tenting as the needle crosses in (C), transseptal sheath in the left atrium in D. Picture courtesy48 . 
RA &#8211; Right Atrium, LA &#8211; Left Atrium, FO &#8211; Foramen Ovale
<ol start="4">
	<li>Arterial access
	<ol>
		<li>Obtain femoral arterial access via the modified Seldinger technique using ultrasound and angiographic guidance at the level of the femoral head. Insert an 0.035&#8221; guidewire.</li>
		<li>Consider use of &#8220;pre-closure&#8221; technique using the variously commercially available vascular access closure devices prior to upsizing arterial access.</li>
		<li>Serially dilate the arterial access site appropriate to the size of the arterial cannula selected. Insert the arterial cannula, remove the introducer and guidewire, wait for back-bleed, and then clamp. Secure the cannula to the patient using the holders.</li>
	</ol>
	</li>
	<li>Connecting the components 
	<ol>
		<li>Make wet-to-wet connections to the cannulas to avoid introduction of any air bubbles in the circuit. This is a crucial step.</li>
		<li>Use saline immersion or constant infusion of saline (&#8220;waterfall&#8221;) over the two ends of the cannulas as they are being connected.</li>
		<li>Connect the transseptal cannula (venous) to the pump inlet which is marked in blue and the arterial cannula to the pump outlet which is marked in red.</li>
		<li>First, remove the venous clamps and start the pump (from the controller box). Then release the other clamps sequentially, constantly checking for any air, releasing the arterial clamp last.</li>
		<li>Adjust pump speed (by adjusting the RPMs) to optimize flow. Confirm the position of the cannula under fluoroscopy and TEE or ICE and secure the circuit to patient.</li>
		<li>Maintain therapeutic anticoagulation (activated clotting time ACT at 180&#8211;220s or activated partial thromboplastin time aPTT at 65&#8211;80s) for as long as the pump is in place to prevent pump thrombosis and stroke. This is a crucial step.</li>
	</ol>
	</li>
</ol>
3. Right Atrium to Pulmonary Artery Bypass (RAPAB) system placement
<ol>
	<li>Initiate the controller, prime the lower chamber of the pump and check for any air bubbles - same steps described as above.</li>
	<li>Prime the upper chamber of the pump, check for any air and clamp it - same steps described as above.</li>
	<li>Patient procedure
	<ol>
		<li>Obtain venous access at the right internal jugular (RIJ) vein via modified Seldinger technique under ultrasound guidance.</li>
		<li>Insert a Pulmonary Artery (PA) Catheter with a 0.035&#34; lumen and advance it to the main PA just before the bifurcation. Insert a stiff-bodied 0.035&#34; guidewire and remove the PA Catheter.</li>
		<li>Anticoagulate the patient (ACT &#62; 250 s).</li>
		<li>Dilate the venous access site sequentially using the stepwise dilators provided in the package until the desired size is reached (29 French or 31 French).</li>
		<li>Insert the venous cannula (e.g., ProtekDuo) over the guidewire.</li>
		<li>Remove the guidewire, wait for back-bleed, and then clamp the distal port which is marked as &#34;Distal.&#34;</li>
		<li>Remove the hemostasis cap, wait for back-bleed, and clamp the proximal port which is marked as &#34;Proximal.&#34; Secure the cannula to patient via sutures.</li>
		<li>Verify the cannulas and make wet-to-wet connections from the pump to the cannula.</li>
		<li>Connect the proximal cannula to the pump inlet which is marked in blue and the distal cannula to the pump outlet which is marked in red. Turn on the pump (from the controller).</li>
		<li>Release clamps sequentially, constantly checking for any air bubbles. Adjust pump speed (by controlling the RPMs) to optimize flow.</li>
		<li>Confirm cannula position under fluoroscopy (may use TEE guidance to confirm position in the main PA) and secure the circuit to patient. Maintain therapeutic anticoagulation (ACT at 180-220 s; aPTT at 65-80 s).</li>
	</ol>
	</li>
</ol>
4. Device removal
NOTE: Once the patient&#39;s end organ function has improved and hemodynamics have stayed stable with either LV&#160;recovery or advanced therapies such as durable LVAD placement/transplant, the device can be removed.
<ol>
	<li>Before removing the device, slowly turn down the speed by 0.5 L/min in a stepwise manner, carefully observing the hemodynamics to make sure there is adequate CO and normal filling pressures with less support (also known as the ramp down or turn down study).</li>
	<li>Turn off the pump once the turndown study is successful.</li>
	<li>Make sure the ACT is &#60; 150 seconds before removing the arterial cannula. Tighten the previously placed intravascular suture to occlude the arteriotomy site or manual pressure can be held for at least 40 minutes to ensure hemostasis.</li>
	<li>Withdraw the transseptal cannula into the IVC and remove it slowly from the femoral vein. Apply a figure of 8 suture to the venous site and additionally, hold manual pressure over the site to achieve hemostasis. 
	NOTE: The atrial septal defect (ASD) is usually small and is not closed routinely.</li>
	<li>Post procedure, perform continuous monitoring of patient&#39;s hemodynamics and end organ function to ensure stability.</li>
	<li>Removal of RAPAB.
	<ol>
		<li>Similar to the LAFAB removal, when the patient&#39;s end-organ function has stabilized with recovery or advanced therapies, slowly turn down the pump by 0.5 L/min, carefully observing the hemodynamics.</li>
		<li>Turn off the pump when turn-down study is successful.</li>
		<li>Once ACT is &#60; 150 seconds, remove the venous cannula from the neck and place a figure of 8 suture to secure the puncture site. Hold manual pressure in addition to the suture to achieve complete hemostasis.</li>
		<li>Post removal, closely monitor patient&#39;s hemodynamics and end-organ function to ensure stability.</li>
	</ol>
	</li>
</ol>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Complication</td>
			<td>Risk factors</td>
			<td>Timing of occurrence</td>
			<td>Precaution</td>
			<td>Management</td>
		</tr>
		<tr>
			<td>Cardiac perforation and tamponade</td>
			<td>Inadvertent advancement of needle or dilator or sheath along the posterior free wall of left atrium.</td>
			<td>During transseptal puncture, placement of inflow cannula</td>
			<td>Accurate assessment of inter-atrial septum on TEE or ICE and optimizing the site and angle of transseptal puncture via angiography and echo.</td>
			<td>Immediate pericardiocentesis to relieve tamponade. May need surgical intervention.</td>
		</tr>
		<tr>
			<td>Acute limb ischemia distal to arterial cannulation</td>
			<td>Small caliber vessels housing large cannulas, pre-existing peripheral arterial disease</td>
			<td>Immediately post procedure</td>
			<td>Peripheral angiogram prior to cannulation.</td>
			<td>Placement of distal perfusion catheter, vascular surgery assistance in severe cases.</td>
		</tr>
		<tr>
			<td rowspan="2">Hemolysis, retroperitoneal bleeding, vascular complications such as pseudoaneurysm formation.</td>
			<td rowspan="2">Higher pump speeds, pump thrombosis, DIC, anticoagulation</td>
			<td rowspan="2">Anytime on the pump</td>
			<td>Optimize pump speed for every patient individually. Avoid supratherapeutic anticoagulation.</td>
			<td rowspan="2">Reducing pump speed, maintaining therapeutic range of anticoagulation.</td>
		</tr>
		<tr>
			<td>Optimal site of arterial access at the femoral head in the common femoral artery.</td>
		</tr>
		<tr>
			<td>Residual atrial septal defect</td>
			<td>Multiple attempts for transseptal access</td>
			<td>After decannulation</td>
			<td></td>
			<td>Hemodynamically significant defects can be closed percutaneously.</td>
		</tr>
	</tbody>
</table>
Table 1: Complications of LAFAB device33.

Sandeep Nathan - Disclosures: Consultant, Abiomed, Getinge, CSI, Inc.
Alexander Truesdell - Disclosures: Consultant, Abiomed Inc.
Poonam Velagapudi - Disclosures: Advisory board for Womens&#8217; Health Initiative, Abiomed

Hemodynamics of LAFAB&#160;device: 
The hemodynamic profile of the LAFAB device is distinct from other pVADs. By draining blood directly from the LA&#160;and returning it to the femoral artery, the device bypasses the LV completely. In doing so, it reduces LV end diastolic volume and pressure, contributing to improved LV geometry, and thereby effecting a decrease in LV stroke work. However, by returning the blood back into the iliac artery/descending aorta, afterload increases. This results in loading of the LV via elevated left ventricular end-systolic pressure (LVESP). Overall, the pressure-volume loop narrows and shifts modestly to the left34. The result is a reduction in myocardial workload and decreased oxygen consumption35. The LVEDP and LVESP may be optimized by increasing pump speed, further unloading the LV36.
The advantages of the LAFAB device include decompression of the LV and decreased stroke work, leading to myocardial recovery. LAFAB unloads the LV indirectly by venting the LA&#160;(and does not require a separate device for LV unloading). It can provide cardiac support up to 4.5 L/min at the bedside, and its durability has been well established up to 2 weeks in vivo37.
Disadvantages of LAFAB lie in the advanced procedural skills required for device placement, as transseptal puncture is not an ubiquitous cardiac catheterization lab skill. The need for TEE or ICE as well as fluoroscopy limits the use of this device at bedside in emergent situations. Femoral vascular access prevents ambulation&#160;and adversely affects patient rehabilitation. As with other MCS, both hemolysis and access site complications may also be significant when they occur. Residual ASD may also occur and adversely affect outcomes in patients bridged to recovery.
Contraindications to LAFAB&#160;device: 
Absolute contraindications to LAFAB system use include pre-existing VSD, severe AI, LA thrombus, and severe PVD precluding device insertion38.
Right Atrium to Pulmonary Artery Bypass (RAPAB) for right ventricular failure: 
Right ventricular (RV) dominant or biventricular CS is fatal&#160;with in-hospital mortality rates ranging up to 75%39. Various MCS devices have been successfully used in the management of RV CS. Similar to the LAFAB system, there is also a novel RV support device draining blood from the RA&#160;to the PA. It is called the ProtekDuo&#160;system (Figure 4), which can provide up to 4 Lpm of flow for the RV40. It consists of a long 31 F (also available in smaller sizes) dual lumen cannula that can be positioned from the internal jugular vein through the RA and RV, into the main PA41. The system is supported by a centrifugal pump similar to the LAFAB system. It empties blood from the RA and returns it to the main PA, bypassing the RV. It may also be connected to an oxygenator for pulmonary support. The RAPAB system helps unload the RV and reduces RV stroke work42. This device is being used increasingly in RV CS43, massive pulmonary embolism44, and postcardiotomy RV failure after LVAD or transplant45. The bulk of the data for RV support comes from the TandemHeart Experiences and Methods (THEME) registry46, where the RAPAB system was used in 30 patients with RV failure of various etiologies, with a 30-day survival of 72.4%, and most patients being bridged to recovery.
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/62140/62140fig4v2.jpg" /> 
Figure 4: Schematic of ProTek Duo system. Image courtesy of TandemLife, a wholly owned subsidiary of LivaNova US Inc. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62140/62140fig4v2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Use of the LAFAB circuit may provide differential benefit over a transvalvular axial flow pump such as Impella in a number of specific clinical scenarios. As stated previously, the LifeSPARC pump is capable of delivering supraphysiologic levels of flow (up to 8 L/min) with current cannula configurations and thus larger patients and those not adequately supported or fully unloaded on transvalvular axial flow pumps (Impella 2.5 L or CP 4 L) devices may benefit from LAFAB. Secondly, patients with prosthetic aortic valves or unfavorable aortic valve/root anatomy such as those with critical AS or aortic valve endocarditis and patients with LV thrombus may be preferentially considered for LAFAB. Finally, LAFAB may be part of a staged support strategy that began with TandemLife VA-ECMO for acute cardiopulmonary rescue followed by subsequent LA drainage into the circuit, thus effectively providing near-complete biventricular support plus oxygenation.
The LAFAB device is an effective and safe pVAD that can be used in acute or chronic LV failure providing up to 4.5 to 5 Lpm of circulatory support as well as indirect LV unloading via LA&#160;decompression. The need for transseptal access may limit the widespread use of this device for emergent LV support in CS. Although observational data suggests both safety and efficacy of the device in both CS and HRPCI, well-conducted large, randomized control trials are needed. In the meantime, results of the ongoing THEME registry may shed more light on the real-world outcomes in patients managed with the LAFAB device.

Cardiogenic shock (CS) is a state of tissue hypoperfusion with or without concomitant hypotension, in which the heart is unable to deliver sufficient blood and oxygen to meet the body&#39;s demands, resulting in organ failure. It is classified into stages A to E by the Society of Cardiovascular Angiography and Interventions (SCAI): stage A - patients at risk for CS; stage B - patients at beginning stage of CS with hypotension or tachycardia without hypoperfusion; stage C - classic CS with cold and wet phenotype requiring inotropes/vasopressors or mechanical support to maintain perfusion; stage D - deteriorating on current medical or mechanical support requiring escalation to more advanced devices; and stage E - includes patients with circulatory collapse and refractory arrhythmias who are actively experiencing cardiac arrest with ongoing cardiopulmonary resuscitation1. The most common causes of CS are acute MI (AMI) representing 81% of cases in a recently reported analysis2, and acute decompensated heart failure (ADHF). CS is classically characterized by congestion and impaired perfusion, manifested by elevated filling pressures (pulmonary capillary wedge pressure [PCWP], left ventricular end-diastolic pressure [LVEDP], central venous pressure [CVP], and right ventricular end-diastolic pressure [RVEDP]), decreased cardiac output (CO), cardiac index (CI), cardiac power output (CPO), and end-organ malfunction3. In the past, the only available treatments for AMI complicated by CS were early revascularization and medical management with inotropes and/or vasopressors4. More recently, with the advent of mechanical circulatory support (MCS) devices and the recognition that escalation of vasopressors is associated with increased mortality, there has been a paradigm shift in the treatment of both AMI and ADHF related CS5,6.
In the current era of percutaneous ventricular assist devices (pVAD), there are a number of MCS device platforms/configurations available, which provide univentricular or biventricular circulatory and ventricular support with and without oxygenation capability7. Despite steady increases in the use of pVADs to treat both AMI and ADHF CS, mortality rates have remained largely unchanged5. With emerging evidence for possible clinical benefits to early unloading of the left ventricle (LV) in AMI8 and early use of MCS in AMI CS9, the use of MCS continues to increase.
The Left Atrial to Femoral Artery Bypass (LAFAB) MCS device bypasses the LV by draining blood from the left atrium (LA) and returning it to the systemic arterial circulation via the femoral artery (Figure 1). It is supported by an external centrifugal pump that offers 2.5-5.0 liters per minute (L/m) flow (new generation pump, designated as LifeSPARC, capable of up to 8 L/m flow) depending on the size of the cannulas. Once the blood is extracted from the LA via the transseptal venous cannula, it passes through the external centrifugal pump which recirculates the blood back into the patient&#39;s body via the arterial cannula placed in the femoral artery.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62140/62140fig01.jpg" /> 
Figure 1: LAFAB setup. Image courtesy of TandemLife, a wholly owned subsidiary of LivaNova US Inc. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62140/62140fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >For LAFAB (TandemHeart)</td>
			<td ></td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >Factory Supplied Equipment for circuit connections.</td>
			<td >TandemLife</td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >ProtekSolo 15 Fr or 17 Fr Arterial Cannula&#160;</td>
			<td >TandemLife</td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >ProtekSolo 62 cm or 72 cm Transseptal Cannula&#160;</td>
			<td >TandemLife</td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >TandemHeart Controller&#160;</td>
			<td >TandemLife</td>
			<td ></td>
			<td>For adjusting flows/RPM</td>
		</tr>
		<tr >
			<td >TandemHeart Pump&#160;</td>
			<td >LifeSPARC</td>
			<td ></td>
			<td>Centrifugal pump</td>
		</tr>
		<tr >
			<td >For RAPAB (ProtekDuo)</td>
			<td ></td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >Factory Supplied Equipment to complete the circuit.&#160;</td>
			<td >TandemLife</td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >ProtekDuo&#160; 29 Fr or 31 Fr Dual Lumen Cannula&#160;</td>
			<td >TandemLife</td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >TandemHeart Controller&#160;</td>
			<td >TandemLife</td>
			<td ></td>
			<td>For adjusting flows/RPM</td>
		</tr>
		<tr >
			<td >TandemHeart Pump&#160;</td>
			<td >LifeSPARC</td>
			<td ></td>
			<td>Centrifugal pump</td>
		</tr>
	</tbody>
</table>

use of a percutaneous ventricular assist device/left atrium to femoral artery bypass system for cardiogenic shock

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the left ventricle by draining blood from the left atrium (LA) and returning it to the systemic arterial circulation via the femoral artery. It can provide flows ranging from 2.5-5 L/min depending on the size of the cannula. Here, we discuss the mechanism of action of LAFAB, available clinical data, indications for its use in cardiogenic shock, steps of implantation, post-procedural care, and complications associated with the use of this device and their management.
We also provide a brief video of the procedural component of device therapy, including the pre-placement preparation, percutaneous placement of the device via transseptal puncture under echocardiographic guidance and the post-operative management of device parameters.

Clinical applications of LAFAB device 
The technique and feasibility of a percutaneous trans-atrial left ventricular bypass system were first described in the 1960s by Dennis et al.11,12. However transseptal puncture was not initially widely adopted due to complications with the septostomy technique. Over the last decade, with advancements in the field of percutaneous interventions, operators have accumulated experience with atrial septostomy, which has led to a resurgence of the transseptal ventricular assist device or LAFAB device.
From the initial clinical studies conducted in the 1990s, the LAFAB strategy has demonstrated a high level of myocardial preservation with larger decrease in infarct size, and greater LV unloading in AMI CS, as compared to the intra-aortic balloon pump (IABP)13.
LAFAB device for cardiogenic shock 
The LAFAB circuit is most widely used in the setting of CS, where it has been shown to be safe and effective in augmenting CO14. A 2006 randomized trial comparing the LAFAB device to IABP in CS15 in 42 patients demonstrated that the LAFAB device was more effective in lowering PCWP and improving CI (1.2 &#177; 0.8 [P &#60; .05 vs baseline]), although mortality did not differ between the two groups. The incidence of severe adverse events was&#160;not significantly different between the two groups in this small cohort. Another trial comparing IABP and LAFAB showed significant improvement in cardiac power index with the LAFAB device (0.22 to 0.37 W/m2, p&#60;0.001), but with a trend towards more complications and no mortality benefit in the LAFAB group16. More patients in the LAFAB group experienced significantly higher acute limb ischemia necessitating revascularization (n=7 vs. n=0, P=0.009) and bleeding complications (n=19 vs. n=8, P=0.002). There was also a trend towards increased incidence of disseminated intravascular coagulopathy in the LAFAB group. More recently,&#160;Kar et al. published a study of 117 patients who underwent LAFAB implantation for severe CS refractory to IABP and vasopressor therapy18. Eighty patients had ischemic cardiomyopathy, and 37 had non-ischemic cardiomyopathy. There was an immediate improvement in hemodynamics and end organ perfusion in both groups. CI increased from 0.53 L/min&#183;m2&#160;to 3.0 L/min&#183;m2, p&#60;0.001 and PCWP decreased from 31.53 &#177; 10.2 mmHg to 17.29 &#177; 10.82 mmHg, p &#60; 0.001).&#160;Mortality rates at 1 and 6 months were 40.2% and 45.3% respectively.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Parameter</td>
			<td>Pre-implantation IABP</td>
			<td>Pre-implantation VAD</td>
			<td>P-value</td>
			<td>Post-implantation IABP</td>
			<td>Post-implantation VAD</td>
			<td>P-value</td>
		</tr>
		<tr>
			<td>Cardiac output (L/min)</td>
			<td>3.0 (2.5&#8211;4.0)</td>
			<td>3.5 (3.3&#8211;4.2)</td>
			<td>0.29</td>
			<td>3.3 (2.9&#8211;4.3)</td>
			<td>4.5 (4.0&#8211;5.4)</td>
			<td>0.007</td>
		</tr>
		<tr>
			<td>CI (L/min/m2)</td>
			<td>1.5 (1.3&#8211;2.0)</td>
			<td>1.7 (1.5&#8211;2.1)</td>
			<td>0.35</td>
			<td>1.7 (1.5&#8211;2.1)</td>
			<td>2.3 (1.9&#8211;2.7)</td>
			<td>0.005</td>
		</tr>
		<tr>
			<td>Blood pressure mean (mmHg)</td>
			<td>64 (57&#8211;74)</td>
			<td>63 (51&#8211;70)</td>
			<td>0.50</td>
			<td>67 (62&#8211;84)</td>
			<td>74 (70&#8211;84)</td>
			<td>0.38</td>
		</tr>
		<tr>
			<td>CPI (W/m2)</td>
			<td>0.22 (0.18&#8211;0.30)</td>
			<td>0.22 (0.19&#8211;0.30)</td>
			<td>0.72</td>
			<td>0.28 (0.24&#8211;0.36)</td>
			<td>0.37 (0.30&#8211;0.47)</td>
			<td>0.004</td>
		</tr>
		<tr>
			<td>SVR (dyn&#215;s&#215;cm&#8722;5)</td>
			<td>1440 (1034&#8211;1758)</td>
			<td>1049 (852&#8211;1284)</td>
			<td>0.16</td>
			<td>1388 (998&#8211;1809)</td>
			<td>1153 (844&#8211;1425)</td>
			<td>0.08</td>
		</tr>
		<tr>
			<td>Heart rate (beats/min)</td>
			<td>122 (92&#8211;130)</td>
			<td>113 (107&#8211;121)</td>
			<td>0.57</td>
			<td>115 (90&#8211;125)</td>
			<td>105 (100&#8211;116)</td>
			<td>0.94</td>
		</tr>
		<tr>
			<td>PCWP (mmHg)</td>
			<td>27.0 (20.0&#8211;30.0)</td>
			<td>20.0 (18.0&#8211;23.0)</td>
			<td>0.02</td>
			<td>21.5 (17.0&#8211;26.0)</td>
			<td>16.0 (12.5&#8211;19.0)</td>
			<td>0.003</td>
		</tr>
		<tr>
			<td>Central venous pressure (mmHg)</td>
			<td>13.0 (11.0&#8211;16.5)</td>
			<td>11.0 (9.0&#8211;15.3)</td>
			<td>0.29</td>
			<td>12.0 (10.0&#8211;17.5)</td>
			<td>10.0 (8.0&#8211;12.0)</td>
			<td>0.06</td>
		</tr>
		<tr>
			<td>PAP mean (mmHg)</td>
			<td>32.5 (27.5&#8211;38.0)</td>
			<td>28.0 (24.5&#8211;34.8)</td>
			<td>0.45</td>
			<td>28.5 (25.5&#8211;33.5)</td>
			<td>24.5 (20.0&#8211;26.0)</td>
			<td>0.007</td>
		</tr>
		<tr>
			<td>Serum lactate (mmol/L)</td>
			<td>3.8 (3.5&#8211;6.7)</td>
			<td>4.5 (3.1&#8211;6.5)</td>
			<td>0.53</td>
			<td>3.25 (2.7&#8211;7.0)</td>
			<td>2.8 (2.3&#8211;3.5)</td>
			<td>0.03</td>
		</tr>
		<tr>
			<td>Standard base excess (mmol/L)</td>
			<td>&#8722;6.8 [&#8722;8.3&#8211;(&#8722;3.9)]</td>
			<td>&#8722;5.1 [&#8722;7.5&#8211;(&#8722;4.4)]</td>
			<td>0.74</td>
			<td>&#8722;4.3 [&#8722;8.8&#8211;(&#8722;2.3)]</td>
			<td>&#8722;4.3 [&#8722;6.1&#8211;(&#8722;3.3)]</td>
			<td>0.28</td>
		</tr>
		<tr>
			<td>pH</td>
			<td>7.34 (7.28&#8211;7.38)</td>
			<td>7.28 (7.24&#8211;7.36)</td>
			<td>0.50</td>
			<td>7.36 (7.28&#8211;7.41)</td>
			<td>7.33 (7.31&#8211;7.40)</td>
			<td>0.49</td>
		</tr>
	</tbody>
</table>
Table 2: Table of results for hemodynamic improvement post LAFAB compared with intra-aortic balloon pump. Adapted from Thiele et al.17.
A 10-patient report also demonstrated successful LAFAB device use in patients with severe aortic stenosis (AS) and CS17. In this case series, the LAFAB device was used as a temporizing measure to stabilize hemodynamics and end-organ function prior to definitive valve replacement. Eight&#160;patients received it in the cardiac catheterization lab before surgical valve replacement with improved renal function prior to surgery and 2 patients received the device support in the operating room after valve replacement. Overall, 3&#160;patients died17.
LAFAB&#160;device as a bridge to transplant/durable VAD 
Another important application of the LAFAB device is in end-stage heart failure, where they are used as a bridge to definitive therapy - durable left ventricular assist device (LVAD) or cardiac transplantation19.
In a series of 25 patients with CS20, 44% of patients underwent placement of durable LVAD of which&#160;30% recovered, and 36% died on support. The mean duration of LAFAB support was 4.8 &#177; 2.1 days. Fifty six % of patients experienced device-related complications, of which 90% were&#160;vascular access complications. Gregoric et al. reported a series of 9 patients with end-stage cardiomyopathy and refractory shock who were bridged with the LAFAB device to a durable LVAD. Eight of these 9&#160;patients were supported with IABP prior to placement of&#160;LAFAB device. Mean duration to durable LVAD was 5.9 days. All 9 patients with CS who received the LAFAB device showed improvement in their hemodynamics and end-organ function on LAFAB support before undergoing LVAD implantation21.
In another series of 5 critically ill patients with CS22, the LAFAB device was placed emergently for LV support as a bridge to transplantation. The mean duration of support was 7.6 &#177; 3.2 days, and all 5&#160;patients underwent cardiac transplantation successfully. No device-related complications were reported in this cohort.
Agarwal et al. in 2015&#160;described a rare, interesting case of durable LVAD thrombosis with CS treated successfully with fibrinolytic therapy and temporary support with LAFAB23.
LAFAB&#160;device for high-risk percutaneous interventions 
The LAFAB device has been studied and utilized extensively for high-risk percutaneous coronary interventions (HRPCI)25,26,27,28 with device-related vascular complications within acceptable ranges compared to other comparable devices. In a recent series of 37 patients who underwent LAFAB device placement for CS, 28 patients&#160;underwent HRPCI successfully while being supported with the LAFAB device. Seventy one percent of patients in the cohort were successfully discharged home. The mean EuroSCORE was 11 &#177; 3.4, indicating a high complexity of this critically ill cohort. The authors concluded that the LAFAB device could be used safely and effectively for HRPCI29. In addition to HRPCI, the LAFAB device has also been used for high risk patients undergoing percutaneous aortic valve replacement, as demonstrated in one small series30. Finally, there is also a small 2-patient report of successful LAFAB device use for post-cardiotomy shock31.

Watch this Scientific Journal Video about Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock at JoVE.com

Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock

The following article describes the stepwise procedure for placement of a device (e.g., Tandemheart) in cardiogenic shock (CS) that is a percutaneous left ventricular assist device (pLVAD) and a left atrial to femoral artery bypass (LAFAB) system that bypasses and supports the left ventricle (LV) in CS.

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the ...

use-percutaneous-ventricular-assist-deviceleft-atrium-to-femoral

Nanyang Technological University

Research

JoVE Journal

Medicine

3.4K Views.  University of Nebraska Medical Center. The following article describes the stepwise procedure for placement of a device (e.g., Tandemheart) in cardiogenic shock (CS) that is a percutaneous left ventricular assist device (pLVAD) and a left atrial to femoral artery bypass (LAFAB) system that bypasses and supports the left ventricle (LV) in CS. 

Video: Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock

Use of a Hanging Weight System for Coronary Artery Occlusion in Mice

Murine studies of acute injury are an area of intense investigation, as knockout mice for different genes are becoming increasingly available 1-38. Cardioprotection by ischemic preconditioning (IP) remains an area of intense investigation. To further elucidate its molecular basis, the use of knockout mouse studies is particularly important 7, 14, 30, 39. Despite the fact that previous studies have already successfully performed cardiac ischemia and reperfusion in mice, this model is technically very challenging. Particularly, visual identification of the coronary artery, placement of the suture around the vessel and coronary occlusion by tying off the vessel with a supported knot is technically difficult. In addition, re-opening the knot for intermittent reperfusion of the coronary artery during IP without causing surgical trauma adds additional challenge. Moreover, if the knot is not tied down strong enough, inadvertent reperfusion due to imperfect occlusion of the coronary may affect the results. In fact, this can easily occur due to the movement of the beating heart.
Based on potential problems associated with using a knotted coronary occlusion system, we adopted a previously published model of chronic cardiomyopathy based on a hanging weight system for intermittent coronary artery occlusion during IP 39. In fact, coronary artery occlusion can thus be achieved without having to occlude the coronary by a knot. Moreover, reperfusion of the vessel can be easily achieved by supporting the hanging weights which are in a remote localization from cardiac tissues.
We tested this system systematically, including variation of ischemia and reperfusion times, preconditioning regiments, body temperature and genetic backgrounds39. In addition to infarct staining, we tested cardiac troponin I (cTnI)
as a marker of myocardial infarction in this model. In fact, plasma levels of cTnI correlated with infarct sizes (R2=0.8). Finally, we could show in several studies that this technique yields highly reproducible infarct sizes during murine IP and myocardial infarction6, 8, 30, 40, 41. Therefore, this technique may be helpful for researchers who pursue molecular mechanisms involved in cardioprotection by IP using a genetic approach in mice with targeted gene deletion. Further studies on cardiac IP using transgenic mice may consider this technique.

A murine model for myocardial ischemia and ischemic preconditioning is an important tool study cardioprotective mechanisms in vivo. Here, we report an easy applicable in situ model for cardiac IP using a hanging-weight system for coronary artery occlusion.

Murine studies of acute injury are an area of intense investigation, as knockout mice for different genes are becoming increasingly available 1-38. ...

Use of a Hanging-weight System for Isolated Renal Artery Occlusion

In hospitalized patients, over 50% of cases of acute kidney injury (AKI) are caused by renal ischemia 1-3. A recent study of hospitalized patients revealed that only a mild increase in serum creatinine levels (0.3 to 0.4 mg/dl) is associated with a 70% greater risk of death than in persons without any increase 1. Along these lines, surgical procedures requiring cross-clamping of the aorta and renal vessels are associated with a renal failure rates of up to 30% 4. Similarly, AKI after cardiac surgery occurs in over 10% of patients under normal circumstances and is associated with dramatic increases in mortality. AKI are also common complications after liver transplantation. At least 8-17% of patients end up requiring renal replacement therapy 5. Moreover, delayed graft function due to tubule cell injury during kidney transplantation is frequently related to ischemia-associated AKI 6. Moreover, AKI occurs in approximately 20% of patients suffering from sepsis 6.The occurrence of AKI is associated with dramatic increases of morbidity and mortality 1. Therapeutic approaches are very limited and the majority of interventional trials in AKI have failed in humans. Therefore, additional therapeutic modalities to prevent renal injury from ischemia are urgently needed 3, 7-9. 
To elucidate mechanisms of renal injury due to ischemia and possible therapeutic strategies murine models are intensively required 7-13. Mouse models provide the possibility of utilizing different genetic models including gene-targeted mice and tissue specific gene-targeted mice (cre-flox system). However, murine renal ischemia is technically challenging and experimental details significantly influence results. We performed a systematic evaluation of a novel model for isolated renal artery occlusion in mice, which specifically avoids the use of clamping or suturing the renal pedicle 14. This model requires a nephrectomy of the right kidney since ischemia can be only performed in one kidney due to the experimental setting. In fact, by using a hanging-weight system, the renal artery is only instrumented once throughout the surgical procedure. In addition, no venous or urethral obstruction occurs with this technique. We could demonstrate time-dose-dependent and highly reproducible renal injury with ischemia by measuring serum creatinine. Moreover, when comparing this new model with conventional clamping of the whole pedicle, renal protection by ischemic preconditioning is more profound and more reliable. Therefore his new technique might be useful for other researchers who are working in the field of acute kidney injury.

A precise murine model for acute kidney injury (AKI) due to ischemia is an important tool to investigate acute kidney injury and possibly find therapeutic tools to treat renal injury. The hanging weight system offers a tool for immediate and reliable renal artery occlusion and reperfusion without causing renal congestion.

In hospitalized patients, over 50% of cases of acute kidney injury (AKI) are caused by renal ischemia 1-3. A recent study of hospitalized patients ...

Use of a Hanging-weight System for Liver Ischemia in Mice

Acute liver injury due to ischemia can occur during several clinical procedures e.g. liver transplantation, hepatic tumor resection or trauma repair and can result in liver failure which has a high mortality rate1-2. Therefore murine studies of hepatic ischemia have become an important field of research by providing the opportunity to utilize pharmacological and genetic studies3-9. Specifically, conditional mice with tissue specific deletion of a gene (cre, flox system) provide insights into the role of proteins in particular tissues10-13 . Because of the technical difficulty associated with manually clamping the portal triad in mice, we performed a systematic evaluation using a hanging-weight system for portal triad occlusion which has been previously described3. By using a hanging-weight system we place a suture around the left branch of the portal triad without causing any damage to the hepatic lobes, since also the finest clamps available can cause hepatic tissue damage because of the close location of liver tissue to the vessels. Furthermore, the right branch of the hepatic triad is still perfused thus no intestinal congestion occurs with this technique as blood flow to the right hepatic lobes is preserved. Furthermore, the portal triad is only manipulated once throughout the entire surgical procedure. As a result, procedures like pre-conditioning, with short times of ischemia and reperfusion, can be easily performed. Systematic evaluation of this model by performing different ischemia and reperfusion times revealed a close correlation of hepatic ischemia time with liver damage as measured by alanine (ALT) and aspartate (AST) aminotransferase serum levels3,9. Taken together, these studies confirm highly reproducible liver injury when using the hanging-weight system for hepatic ischemia and intermittent reperfusion. Thus, this technique might be useful for other investigators interested in liver ischemia studies in mice. Therefore the video clip provides a detailed step-by-step description of this technique.

We established a novel murine model of a hanging weight system for portal triad occlusion. This technique may be useful for future investigations of ischemia in murine hepatic models.

Acute liver injury due to ischemia can occur during several clinical procedures e.g. liver transplantation, hepatic tumor resection or trauma repair and ...

Use of Animal Model of Sepsis to Evaluate Novel Herbal Therapies

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. It has been routinely simulated in animals by several techniques, including infusion of exogenous bacterial toxin (endotoxemia) or bacteria (bacteremia), as well as surgical perforation of the cecum by cecal ligation and puncture (CLP)1-3. CLP allows bacteria spillage and fecal contamination of the peritoneal cavity, mimicking the human clinical disease of perforated appendicitis or diverticulitis. The severity of sepsis, as reflected by the eventual mortality rates, can be controlled surgically by varying the size of the needle used for cecal puncture2. In animals, CLP induces similar, biphasic hemodynamic cardiovascular, metabolic, and immunological responses as observed during the clinical course of human sepsis3. Thus, the CLP model is considered as one of the most clinically relevant models for experimental sepsis1-3.
Various animal models have been used to elucidate the intricate mechanisms underlying the pathogenesis of experimental sepsis. The lethal consequence of sepsis is attributable partly to an excessive accumulation of early cytokines (such as TNF, IL-1 and IFN-&gamma;)4-6 and late proinflammatory mediators (e.g., HMGB1)7. Compared with early proinflammatory cytokines, late-acting mediators have a wider therapeutic window for clinical applications. For instance, delayed administration of HMGB1-neutralizing antibodies beginning 24 hours after CLP, still rescued mice from lethality8,9, establishing HMGB1 as a late mediator of lethal sepsis. The discovery of HMGB1 as a late-acting mediator has initiated a new field of investigation for the development of sepsis therapies using Traditional Chinese Herbal Medicine. In this paper, we describe a procedure of CLP-induced sepsis, and its usage in screening herbal medicine for HMGB1-targeting therapies.

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection, and can be simulated by a surgical technique termed cecal ligation and puncture (CLP). Here we describe a method to use CLP-induced animal model to screen medicinal herbs for therapeutic agents.

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. It has been routinely simulated in animals by several ...

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 ...

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

Murine Model of Femoral Artery Wire Injury with Implantation of a Perivascular Drug Delivery Patch

Percutaneous interventions including balloon angioplasty and stenting have been used to restore blood flow in vessels with occlusive vascular disease. While these therapies lead to the rapid restoration of blood flow, these technologies remain limited by restenosis in the case of bare metal stents and angioplasty, or reduced healing and possibly enhanced risk of thrombosis in the case of drug eluting stents. A key pathophysiological mechanism in the formation of restenosis is intimal hyperplasia caused by the activation of vascular smooth muscle cells and inflammation due to arterial stretch and injury. Surgeries that induce arterial injury in genetically modified mice are useful for the mechanistic study of the vascular response to injury but are often technically challenging to perform in mouse models due to the their small size and lack of appropriate sized devices. We describe two approaches for a surgical technique that induces endothelial denudation and arterial stretch in the femoral artery of mice to produce robust neointimal hyperplasia. The first approach creates an arteriotomy in the muscular branch of the femoral artery to obtain vascular access. Following wire injury this arterial branch is ligated to close the arteriotomy. A second approach creates an arteriotomy in the main femoral artery that is later closed through localized cautery. This method allows for vascular access through a larger vessel and, consequently, provides a less technically demanding procedure that can be used in smaller mice. Following either method of arterial injury, a degradable drug delivery patch can be placed over or around the injured artery to deliver therapeutic agents.

We describe a surgical technique that produces wire injury in the femoral artery of mice to induce neointimal hyperplasia to serve as a model testing system for the perivascular delivery of therapeutic compounds for the inhibition of restenosis.

Percutaneous interventions including balloon angioplasty and stenting have been used to restore blood flow in vessels with occlusive vascular disease. ...

Use of a Low-flow Digital Anesthesia System for Mice and Rats

A traditional vaporizer depends on flowing gas and atmospheric pressure for passive anesthetic vaporization. Newly developed direct injection vaporizers utilize a syringe pump to directly administer volatile anesthetics into a gas stream. Unlike a traditional vaporizer, it can be used at very low flow rates, making it ideal for use on mice and rats. 
The equipment's capability to use low flow rates could result in a substantial cost savings due to the reduced need for anesthetic agents, compressed gas, and charcoal scavenging filters1. A lower flow rate means less waste of anesthetic gas and likely reduces the risk of anesthetic exposure to laboratory personnel. Thus, the high levels of precision and safety associated with direct injection vaporizers, along with a reduced need for anesthetic agents, compressed gas, and charcoal filters are beneficial for research requiring small animal anesthesia. 
The goal of this protocol is to demonstrate the use of a syringe-driven direct injection vaporizer as part of a digital, low-flow anesthesia system. The direct injection vaporizer is capable of accurately delivering anesthesia at very low flow rates compared to a traditional vaporizer, making it a promising alternative for controlled gas anesthetic delivery to rodents.

Here, we present a protocol to more safely and efficiently administer anesthetic gas to mice using a digital, low flow anesthesia system utilizing a syringe-driven direct injection vaporizer.

A traditional vaporizer depends on flowing gas and atmospheric pressure for passive anesthetic vaporization. Newly developed direct injection vaporizers ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

Murine Echocardiography of Left Atrium, Aorta, and Pulmonary Artery

The present methodology teaches the investigator how to measure and use the LAV as a surrogate of chronic elevations in Left Ventricular diastolic pressure through echocardiography, as well as to obtain measurements of the Aorta and PA diameter in mice.
Mice older than 10 d of age can be analyzed using the present technique. The technique is composed of 3 main steps: set-up, image acquisition, and image analysis. The set-up step consists of getting the mouse anesthetized with 1% isoflurane, shaving it, and taping it in a supine position to a heated EKG board where the image acquisition will take place. The image acquisition step consists of learning to identify the cardiac structures and obtaining all the required images with its correspondent probe and axis in order to be able to calculate volumes and diameters. The image analysis step consists of measuring the previously acquired images with the aid of computer software.
Advantages of the proposed technique include a fast (15 min) procedure that would allow the researcher to evaluate interventions in a non-invasive, non-terminal approach and therefore follow the same mouse over time; each mouse can be used as its own control. This fact plus having the same operator perform all the acquisition and analysis for the entire experiment minimizes the limitation of operator-dependency. The present methodology is useful for mouse researchers in cardiovascular and pulmonary medicine.

The following protocol describes the methodology for the acquisition and analysis of echocardiographic images used to obtain the Left Atrial Volume (LAV), Aorta (Ao) diameter, and Pulmonary Artery (PA) diameter in mice. This technique is a non-invasive, non-terminal procedure that allows assessment of the cardiopulmonary function.