Insertion, Maintenance, and Removal of the Percutaneous Dual Lumen Cannula Right Ventricular Assist Device

Summary

The present protocol provides a detailed description of a percutaneous dual lumen right ventricular assist device and illustrates step-by-step instructions on the safe implanting, managing, and removing the device. Guidance on its use and troubleshooting complications from one of the most significant single-center experiences is also included.

Abstract

Right ventricular (RV) shock, classically characterized by elevated central venous pressure (CVP) with normal to low pulmonary artery (PA) and pulmonary capillary wedge pressures (PCWP), remains a significant cause of morbidity and mortality worldwide if left untreated. Therapies for the treatment of RV shock range from medical management to durable or percutaneous mechanical circulatory support (MCS). A unique MCS device, a percutaneous right ventricular assist device (pRVAD), approved for use by the Food and Drug Administration (FDA) in 2014, works by temporarily off-loading the RV through a single, dual lumen catheter with extracorporeal mechanical support and is capable of shunting blood from the right atrium (RA) to the main PA. Although initially approved as venous-venous extracorporeal membrane oxygenation (VV-ECMO) device, this work will focus on the use of RV support, as ambulatory VV-ECMO strategies have been described previously. The catheter is most commonly inserted through the right internal jugular (IJ) vein into the PA and connected to an external pump, allowing flow up to 5 L/min. This device may be an attractive choice for the treatment of RV shock due to its percutaneous, minimally invasive insertion and removal and its ability to allow patient ambulation while the device is in place. This protocol discusses in detail the equipment, hemodynamic effects, indications, contraindications, complications, currently available research in the literature, and step-by-step instructions on how to implant, manage, and extract the device, along with the guidance on use and troubleshooting complications from one of the largest, single-center experiences with the device.

Introduction

Cardiogenic shock (CS) from right ventricular (RV) failure remains one of the most challenging cardiac pathologies to manage and portends high mortality and morbidity¹. There are three primary pathologic states which may result in RV failure: loss of myocardial contractility, volume overload, and pressure overload². After a heart transplant, loss of RV contractility can be secondary to myocardial ischemia, infarction, or inflammation caused by myocarditis or primary graft dysfunction³. RV volume overload may be secondary to right-sided valvular insufficiency, shunting, or inadequate volume elimination (e.g., renal failure) relative to enteral or intravenous intake⁴. RV pressure overload may result from worsening pulmonary hypertension (pHTN), pulmonary stenosis, acute pulmonary embolus, or decompensated left-sided heart failure, the most common cause of RV failure⁵. Percutaneous treatment options have become one of the mainstays for the treatment of RV CS. Besides medical therapy, multiple devices are available to treat RV failure, including the venous-arterial extracorporeal membrane oxygenation (VA-ECMO), open/central right ventricular assist device (RVAD), Impella RP, TandemHeart RV assist device, and the Protek Duo².

The Protek Duo is the only minimally invasive percutaneous RVAD (pRVAD) with a dual lumen cannula that allows ambulation while the device is in place⁶ and is increasingly being used in RV CS to off-load the RV. Although initially approved as a venous-venous extracorporeal membrane oxygenation (VV-ECMO) device, this work will focus on its use for RV support, as ambulatory VV-ECMO strategies have been described previously⁷. It off-loads the RV by shunting blood from the RA to pulmonary artery (PA) and allows the option to attach a centrifugal flow extracorporeal continuous flow pump with or without an oxygenator to allow for optimal RV support. The device was approved for use in 2014 by the Food and Drug Administration (FDA)⁸. It can provide flows up to 4.5-5 L/min^9,10. Its dual lumen catheter design pulls blood via the proximal inflow cannula in the RA and funnels it out via the central PA, essentially bypassing the RV.

The cannula has two distinct lumens with a wire-reinforced body. Two concentric channels for bidirectional flow within one single cannula allow for simultaneous venous drainage and reinfusion of blood during extracorporeal support. The proximal portion of the device is separated and non-wired allowing for external clamping to prevent blood flow during implantation and extraction of the cannula device. For accurate positioning of the device, the cannula is marked with distal and proximal markers to identify the insertion depth. The distal markers are radiopaque, allowing for visualization of the device on radiographic imaging to determine the position of the catheter within the right atrium (RA). Along with markings, there are fenestrations or holes at the distal tip and mid-portion of the catheter. The six side holes at the distal tip allow blood to flow out of the catheter into the PA. The midshaft holes allow deoxygenated blood to flow into the catheter from the RA (Figure 1). This design enables the use of the device pre-, intra-, and post-operatively throughout the continuum of procedures requiring cardiopulmonary bypass (CPB). For example, the device was used by us in isolation or as part of bi-ventricular temporary support before a durable left ventricular assist device (LVAD). It was then converted to a venous drainage cannula for CPB during the procedure (by "Y" connecting the two limbs to the venous drainage limb of the circuit) and then reverting to RA/PA bypass for RVAD support post-operatively. Additionally, the cannula was also used as a PA vent for left ventricular (LV) unloading/venting in the setting of VA-ECMO with LV distension by applying venous drainage to both the RA and PA ports, again in the preparation setting for the CPB procedures and subsequent conversion to RVAD support.

Currently, two sizes are available, the 29 Fr or 31 Fr (Figure 2). These catheters are designed to optimize ease of insertion and, therefore, have a tapered design to allow the device's distal portion to pass through all the cardiac structures safely. Specifically, the 29 Fr tapers to a 16 Fr, and the 31 Fr tapers to an 18 Fr. Both sizes are made of the same materials. According to the FDA, both sizes are identical in tensile strength, pathway integrity, kink radius, and hemolysis rates. They differ regarding the cannula stiffness and pressure-flow properties, which is expected with a change in cannula diameter. Despite their differences, they are determined to be equivalent in functional capabilities. The larger Fr sizes are typically used for those who require more blood flow to achieve optimal hemodynamic support¹¹.

An essential indication for using the pRVAD is refractory RV failure. This includes RV failure status post LVAD placement, post-cardiotomy status, post-acute myocardial infarction, or post heart transplant status¹². This device is often used in conjunction with other therapies such as diuretics, inotropic agents, vasopressors, and pulmonary vasodilators to provide an individual optimal hemodynamic support while allowing time for remodeling of the native RV. The device has also been documented to have been used in severe pHTN, as mentioned in the example above, and acute myocarditis¹³. In our experience, we have had successful weaning from support and discharge from the hospital using the pRVADin severe pHTN; however, such cases are rare, and in general, RVAD support is avoided in the setting of severe hypertension given increased pressure within the PAs, and therefore would favor decompressing the PAs with VA-ECMO (ambulator strategies if prolonged support is necessary) or RA to left atrium bypass configurations when able.

The pulmonary artery pulsatility index (PAPI) is commonly used with the overall clinical assessment to identify patients who might benefit from minimally invasive management with this device. The PAPI is a validated hemodynamic metric to assess the degree and presence of RV failure. It is calculated using the systolic PA pressure minus the diastolic pulmonary pressure divided by the central venous pressure (CVP). Patients with a PAPI of less than 0.9 should be considered for RV support¹³. The cardiac power output (CPO) can be calculated with the PAPI to differentiate patients who may benefit from RV support therapy. It is calculated by multiplying the mean arterial pressure by the cardiac output and dividing it by 451. If the CPO is less than 0.6, treatment for RV failure may be warranted. If the CPO is greater than 0.6, there is room for interpretation and discussion of possible other therapies¹⁴. However, most evidence recommends RV therapies if the PAPI is less than 0.9, as stated above. Ultimately, the decision for mechanical support is based on clinical assessment with these quantitative metrics as valuable adjuncts in decision making.

Contraindications to use of this mechanical circulatory support (MCS) device include any severe vascular or right heart obstructive pathology, including existing internal jugular (IJ) vein stenosis or thrombosis, severe pulmonary stenosis, and prior tricuspid valve replacement, which precludes safe placement of the device¹¹. A case of acute superior vena cava (SVC) syndrome after a suitable IJ Protek Duo was placed required emergent reconfiguration to an alternate support strategy. In the absence of severe stenosis of the tricuspid valve, tricuspid valve repair is not a contraindication to the use of the device. Pulmonary valve replacement (PVR) is not a contraindication, and there are several reports in the literature of the use of this device within a PVR¹⁵. A relative contraindication to using the pRVADis a history of a pneumonectomy due to ligation of one of the proximal branch PAs with this procedure and concern for wire or cannula injury to the PA stump or excessive pressure on the stump by RVAD flow. Additionally, in cases with extensive chest radiation, the tissue may not allow dilation and placement of the cannula, precludingpRVAD placement.

Several complications are associated with the use of this MCS device. One potential risk with treating RV shock with the device is unmasking LV dysfunction or previously unrecognized bi-ventricular dysfunction. For example, sometimes, with RV failure, the LV appears pseudonormal because of significant underfilling of the LV. However, with an RVAD in place, forward flow is optimized, and increased filling of the LV may unmask LV dysfunction. Many times, these patients may need to be converted to VA-ECMO. Furthermore, the prothrombogenic nature of the cannula puts the patient at risk for thromboembolic events. To combat this problem, it is standard therapy that all patients are treated concomitantly with anticoagulation. However, the addition of anticoagulation therapy has its own risk for bleeding complications such as access site bleeding, gastrointestinal tract bleeding, hemorrhagic stroke, and risk of heparin-induced thrombocytopenia (HITT)¹⁶. Interruptions in anticoagulation due to bleeding complications can cause pump thrombosis. The device needs to be exchanged emergently in this setting. The diagnosis needs to be rapidly elucidated among other causes for acute hemodynamic deterioration and low device flow, including sepsis or hypovolemia/hemorrhage.

Despite all its possible complications, this pRVAD is becoming more common in many hospitals across the United States for the noninvasive management of RV failure. Its portable design allows patients to sit, stand and even ambulate freely if positioned and secured appropriately. It can even be easily removed at the bedside after the device has been weaned. The device is FDA approved for use up to 6 days, but there have been reports of use for as long as weeks to months¹⁷. The device can be used for VV-ECMO support by adding an oxygenator to the circuit at any point while using the device¹⁸. The 31 Fr device also has a rapid deployment (RD) version seen in Figure 3. The RD has been chiefly referenced in literature as a temporary left ventricular support device used as a bridge to other support devices with placement via an apical approach to provide minimally invasive LV support¹⁹.

In contrast to the Protek Duo, the Impella RP is a percutaneous device used for RV support that is inserted into the femoral vein, requires strict bed rest, and does not allow ambulation. It also provides an axial flow compared to the Protek Duo, which provides a centrifugal flow. Centrifugal flow devices have lower GI-related bleeding events with comparable stroke rates¹⁷. Commonly reported complications of the Impella RP include hemorrhaging (42.9%), vascular problems (22.8%), device fragmentation (34.2%), clotting of the system (17.1%), and device disconnection (8.6%)²⁰. Several other RV support devices² are currently being studied. They may hit the market in the future, but for now, this dual cannula device remains an attractive choice as a noninvasive percutaneous device for the short-term treatment of RV failure.

Protocol

The present protocol is approved by the human research ethics committee of the University of Nebraska Medical Center. The protocol follows the guidelines of the human research ethics committee of the same university.

1. Insertion of the device

NOTE: This procedure needs to be ideally performed in a fluoroscopy suite to ensure accurate placement of the device.

1. Prepare the patient.
   NOTE: Any patient >18 years of age, male or female, are eligible for this therapy if anatomy is suitable for appropriate access and delivery of the device. Individuals <18 years old may also be considered for the device if anatomy is suitable.
   1. Identify and expose the access site.
      NOTE: There are four options for inserting this cannula device. It can be placed via right IJ (preferred), left IJ, left subclavian, or right subclavian vein.
   2. Using chlorohexidine-based or iodine-based preparation solution (see Table of Materials), thoroughly clean the access site and surrounding areas. Apply a sterile drape to establish a sterile field in a standard fashion.
2. Self-sterilize. Scrub, gown, and glove following the sterile technique.
3. Sterilize the ultrasound machine. Place a sterile ultrasound probe cover over the ultrasound transducer (see Table of Materials).
4. Using ultrasound guidance, identify venous access.
   NOTE: Exclude any obstructions to venous flow within the target vessel by scanning up and down the vessel with the ultrasound probe.
5. Using the modified Seldinger technique²¹, gain access to the vein.
   1. Anesthetize by injecting up to 10 mL of 1% lidocaine into the subcutaneous tissue at the access site.
   2. Under ultrasound guidance, cannulate the vein using a 5 Fr micropuncture needle.
   3. Under fluoroscopy or transesophageal echocardiographic (TEE) guidance, insert a micropunture wire through the needle ~8-10 cm in the vein. Remove the needle, leaving the wire in place.
      NOTE: Ensure to always hold onto the wire to prevent embolization.
   4. Enlarge the puncture site using a 10-blade, making a small 0.5 cm incision directly over the wire perpendicular to the wire.
      NOTE: Patients tend to bleed directly following this step. It is good to have the equipment readily available to prevent excess bleeding. Also, a 4 x 4 sterile gauze might be required to apply at the incision site to clear the excess blood.
   5. Place a 5 Fr sheath over the wire. Remove the wire leaving the sheath in place.
   6. Then, put an 0.035" wire through the 5 Fr sheath and upsize it to a 9 multi-lumen access catheter (MAC). Once upsized to the 9 MAC, remove the wire.
6. After the sheath placement, float a Swan Ganz catheter in standard fashion through the 9 Fr MAC (see Table of Materials) using fluoroscopy or TEE guidance.
   1. Advance a balloon-tipped catheter (see Table of Materials) through the sheath ~10-20 mm, and then inflate the balloon with 1-2 cc of air.
   2. Under fluoroscopy, advance the inflated balloon-tipped catheter into the RA through the tricuspid valve and the main PA.
7. Insert a 0.035-inch diameter stiff wire (see Table of Materials) through the balloon-tipped catheter into the right PA.
8. After deflating the balloon-tipped catheter, remove the swan while leaving the stiff wire in place.
9. Serially dilate the access site using sequentially larger dilators (Figure 3) by placing the dilators one by one over the stiff wire smallest to largest up to 26 Fr using the device dilators. If using a 31 Fr cannula, dilate up to 30 Fr.
   1. Simultaneously hold the wire at skin level and intermittently maintain pressure to prevent bleeding as appropriate with the left hand and navigate the dilators with the other hand.
      NOTE: This pRVAD does not come with a 30 Fr dilator. A 30 Fr Tracheal dilator (see Table of Materials) is substituted here. Also, note that each subsequent dilatation increases access site size, and therefore each step up in dilation may cause increased bleeding risk.
10. Administer intravenous (IV) unfractionated heparin boluses to achieve an activated clotting time (ACT) of ~250, depending on the patient's bleeding risk.
    NOTE: The ACT goal may need to be adjusted lower for patients with a higher bleeding risk (e.g., fresh sternotomy). The ACT goal listed above uses a Hemochron device (see Table of Materials). To achieve the recommended ACT goal, administer 70-100 units/kg of IV unfractionated heparin. In case the therapeutic ACT level is not achieved with the initial bolus, additional boluses may be administered based on the achieved ACT level, but exact dosing recommendations are not provided by the guidelines.
11. Once a therapeutic ACT is achieved, insert the pRVAD device.
    1. Advance the device's introducer and cannula assembly over the guidewire.
       NOTE: The cannula size varies from patient to patient. Hence, the size of the cannula assembly depends on the cannula selected.
    2. Before pushing the device through the skin over the wire, push the wire retrograde through the device until the wire is observed coming out of the distal tip.
    3. Once the wire is observed and secured, advance the introducer cannula through the skin over the wire.
    4. Advance the device past the tricuspid and pulmonary valves through the main PA and into the right PA.
       NOTE: Correct positioning is confirmed with echocardiography, transduction of intracardiac pressures on the PA catheter, and/or fluoroscopy. Deploying the device deep into the right PA and then pulling it back into the appropriate position just distal to the bifurcation is recommended to avoid deploying the cannula too shallow and preventing the device from prolapsing into the RV, which can be catastrophic. The device can also be deployed in the left PA but tends to have a smoother curve in the RPA.
12. Remove the introducer and stiff wire when the device is in the desired location (Figure 4).
    1. While maintaining the device's position under visualization with fluoroscopy, first remove the introducer and then pull gently on the stiff wire till the entire wire is removed.
    2. Clamp the cannula on the proximal and distal ports (Figure 2).
    3. Reassess positioning of the cannula via TEE and/or fluoroscopy.
       ​NOTE: Typically, the device is initially intentionally placed with the tip in the right PA, and then with the wire and introducer out, the device is gently retracted until the tip is just proximal to the PA bifurcation on TEE and fluoroscopic imaging and at least 3-4 cm past the pulmonic valve.
13. Secure the device cannula in place.

2. Connecting, activation, and maintenance of the device

1. De-air and connect the standard tubing provided in the device kit.
   1. Ensure the circuit is primed and de-aired before connecting the tubing.
   2. Connect the outflow tubing marked with a red stripe using fluid-to-fluid contact to the cannula port for return blood drainage (from the pump to the patient).
   3. Connect the pump inflow tubing marked with a blue stripe using a fluid-to-fluid contact to the cannula port for blood drainage (from the patient to the pump).
2. Release the clamps.
3. Turn on the centrifugal pump starting at 5,500 revolutions per minute (RPM).
   1. Gradually increase the pump RPMs until the desired level of flow is achieved.
4. Recheck positioning of the pump.
   NOTE: Verifying the positioning of the cannula tip may be facilitated at this stage, given color flow at the outlet ports on TEE.
5. Secure the pump.
   1. Secure the pump using either the voyager vest (see Table of Materials) or the wrap (Figure 5) to maintain device stability and allow for patient comfort and ambulation.
6. Perform maintenance of the device.
   1. Monitor the positioning of the device with daily chest radiographs. Monitor patient hemodynamics closely while the device is in to ensure adequate hemodynamic support.
   2. Monitor labs every 6 h, including complete blood count, comprehensive metabolic panel, electrolytes, lactic acid, and centrally drawn mixed venous saturation.

3. Removal of the device

1. Wean the device following the steps below.
   1. Gradually turn down the device's speed while monitoring hemodynamic and cardiac function response.
      NOTE: Typically, this is performed while obtaining an echocardiogram turn-down study focusing on the cardiac function with lower flows on the device. Lactic acid, mixed venous saturation, and liver/renal function need to be monitored frequently. If worsening RV function or observed end-organ dysfunction by abnormal labs is observed at any point, the patient has failed the RV wean and should continue support.
2. If the RV function appears suitable for removing the device and the patient is oxygenating and ventilating well, wean the speed and remove the cannula.
   1. Before removing the cannula, clamp the proximal and distal ports to prevent leakage of blood.
   2. Remove the cannula.
      NOTE: Once the cannula is retracted to where the atrial side ports are exposed, these sites will bleed, and therefore the cannula needs to be pulled smoothly but rapidly. A 2-0 figure-of-eight absorbable suture is placed through the skin or subcutaneous tissue for hemostasis at the entry site.

Results

The device initially gained FDA clearance in the United States after a large randomized control trial, which revealed a 31% improvement in survival in treating acute respiratory distress syndrome with the device used as VV_ECMO²². Eventually, it was approved as a RA to PA bypass. However, the device has not yet been approved for use as an RVAD although at many major centers, the device is already being used as an RVAD substitute in many cases. There are currently ongoing multicenter observati...

Discussion

RV shock portends exceptionally high mortality. It should be recognized early in the disease course and treated aggressively. The Protek Duo is a cutting-edge MCS for the treatment of RV shock that can be placed during any of the SCAI stages of shock. A few critical steps in the placement of the device include: obtaining access using the modified Seldinger technique²¹, sequential dilatation of the access site to appropriate size Fr sheath, floating a balloon-tipped catheter into the main PA, ...

Materials

Name	Company	Catalog Number	Comments
Amplatzer Super Stiff Wire 0.035' x 145 cm	Boston Scientific	M001465631	If not in stock, may use any stiff 0.035" wire.
Avalon Tracheal Dilator	Avalon Laboratories Inc., Rancho Dominguez, CA	12210	This comes in a set. The 30 Fr dilator is the only part used.
Full 29 Protek Duo Kit	LivaNova/ Tandem Life	5820-2916	Cannula, pump, holster, wrap
Full 31 Protek Duo	LivaNova/Tandem Life	5820-3118	Cannula, pump, holster, wrap
Hemochron Signature Elite ACT Testing Device and Supplies	Werfen North America	DCJACT-A and DCJACT-N
Lidocaine	Pharmaceutical	Pfizer
LifeSPARC Centrifugal Pump	LivaNova/ Tandem Life	5840-2417
Micropuncture needle	Cook Medical	G56202	5 Fr
Multi-Lumen Access Catheter	Arrow/Teleflex	AK-21242-CDC	9 Fr
Preparation solution	Pharmaceutical	NA	Chlorohexidine-based or iodine-based
Protek Duo Cannula 29Fr	LivaNova/ Tandem Life	5140-4629	Components: One 29 Fr ProtekDuo Veno-Venous Wire Reinforced Cannula with radiopaque tip markers, One 13 Fr Introducer
Protek Duo Cannula 31Fr	LivaNova/Tandem Life	5140-5131	- 31 Fr x 51 cm Veno-Venous Dual Lumen Cannula with Introducer
Protek Duo Insertion Kit	LivaNova/ Tandem Life	5100-0014	Components: balloon tipped PA catheter, one 0.035 stiff guidewire
Protek Duo RD Cannula	LivaNova/Tandem Life	5820-3631	Cannula, introducer
Swan Ganz Catheter	Edwards Lifesciences	774F75 or 777F8
Ultrasound	Standard vascular ultrasound.	GE
Ultrasound probe cover over the ultrasound transducer	Standard probe cover to match vascular ultrasound transducer	GE
Voyager Vest Kit	LivaNova/Tandem Life	Contact LivaNova	Includes vest and wrap. Should not be used on patients with a known allergy to neoprene.