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

The tandem heart is a percutaneously implanted mechanical circulatory support device that is used for the treatment of cardiogenic shock, particularly in situations like LV thrombus or severe aortic stenosis. And it provides a support of about five liters per minute. Demonstrating today's procedure will be myself and Dr.Swethika Sudaravel, chief cardiology fellow from UNMC.

To set up the controller, begin by opening the box of the device and access the battery door to place the batteries two at a time in the controller with the logo facing away from the controller screen. The batteries should be well seated with the groove on the battery aligning with the key battery housing. After placing the four batteries, attach the controller to the dock, ensuring it is fully seated on the dock.

Then connect the power cord to the power outlet of the controller and plug in the other end of the cord to the wall socket for AC power. Once done use the clamp to mount the dock and controller on an intravenous pole and operate the buttons on the side to turn on the controller. Open the package, and the sterile drape.

Then lay out the components of the priming tray on the sterile table, next, plug the pump drive line into the controller, remove the protective caps on the tubing before inserting the end of the blue tubing into the blue port and the red tubing into the basin. Place the basin in the fill ready, tilted back position, away from the blue port. When the basin is filled with four liters of saline, put the lid and place the basin in the fill ready, tilted back position away from the blue port.

Gently tap the tubing and the pump to remove any small air bubbles present and ensure that all the air has been removed before turning on the pump from the non sterile end in the same way, remove tiny air bubbles in the oxygenator by gently tapping the oxygenator, followed by positioning the outflow tubing at a higher level in the 12 o'clock position for the air bubbles to rise above and escape out. Once all the air bubbles are removed clamp the inflow and outflow tubing and stop the pump, remove the inflow and outflow tubing from the basin and then attach the green oxygen supply tubing to the gas port on the oxygenator to complete the circuit. After preparing the patient in a sterile manner, pass the transesophageal, echocardiogram or TEE probe into the esophagus to obtain the basic images, if using an intracardiac echocardiogram, or ICE, obtain the images after venous access.

Using a TEE probe or ICE, identify the ideal spot for septostomy of the interatrial septum and confirm the absence of any thrombus in the left atrium where the inflow cannula will be positioned, use the Bicaval view on TEE at the region of the phase ovales, to expose the interatrial septum. Using the modified Seldinger technique obtain femoral venous access via ultrasound guidance and insert tape 0.032 inch guidewire into the vein and position the tip in the superior vena cava. Advance the baylis sheath over the guidewire into the superior vena cava, remove the guidewire and under fluoroscopic or TEE ICE guidance, withdraw the baylis sheath towards the interatrial septum.

Using fluoroscopy or TEE ICE, identify the optimal site for transeptal puncture and advance the baylis needle into the interatrial septum, administer anticoagulant to the patient to achieve activated clotting time more than 250 seconds before performing transeptal puncture, then perform transeptal puncture by advancing the baylis needle and sheath into the left atrium. After confirming the sheath is in the left atrium by fluoroscopy, remove the needle and insert a guidewire into the left atrium then remove the baylis sheath. With a two stage dilator, dilate the venous access and the interatrial septum to insert the transeptal cannula.

After advancing the cannula into the left atrium remove the introducer and guidewire and wait for back bleed before clamping. Finally secure the cannula to the patient. Next, obtain femoral arterial access via the modified Seldinger technique using ultrasound and fluoroscopic guidance at the level of the femoral head and insert a 0.035 inch guidewire.

Serially dilate the arterial access site appropriate to the size of the selected arterial cannula, insert the arterial cannula and remove the introducer and guidewire. Wait for back bleed then clamp. Ensuring constant infusion of saline, over the two ends of the cannulas connect the transeptal or venous cannula to the pump inlet marked in blue and the arterial cannula to the pump outlet marked in red, remove the venous clamps first and start the pump from the controller box then release the other clamps sequentially while constantly checking for air in the circuits.

Release the arterial clamp last. To optimize the flow, adjust the pump speed. After confirming the position of the cannula under fluoroscopy and TEE or ICE, secure the circuit to the patient.

To prevent pump thrombosis and stroke, it's crucial to maintain the therapeutic anticoagulation for as long as the pump is in place. The application of left atrium to femoral artery bypass or LAFB may be associated with few complications, such as cardiac perforation, and tamponade, acute limb ischemia and hemolysis. Proper precautionary measures and management procedures are important, avoid complications related to LAFB.

In a trial comparing LAFB and ventricular assist device or VAD, a significant improvement in cardiac power index with the VAD device was observed. The LAFB device was effective in lowering pulmonary capillary wedge pressure and improving cardiac index, VAD displayed significant progress in PCWP and CI.The most important steps of the procedure are performing the transeptal puncture under meticulous imaging guidance, getting arterial access using ultrasound and fluoroscopy and making the vein to vein connections of the circuit.