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Mock Flow Loop for Novel Endovascular Surgery Graft Creation
Mock Flow Loop for Novel Endovascular Surgery Graft Creation
Figure 1: 3D-schematic of a physiologically accurate mock flow loop for measuring fluid pressure to understand the human physiological response (blood pressure) of the aortic arch arteries due to the placement of a graft during thoracic endovascular aortic repair (TEVAR). Learn more about each component here.
Figure 2: Insertion of catheter through femoral artery. Catheter snakes through, up the aorta
TEVAR Procedure
TEVAR Procedure
Thoracic Endovascular Aortic Repair (TEVAR) refers to a minimally invasive surgery approach that involves placing a stent-graft in the thoracic or thoracoabdominal aorta for the treatment of a weakening in the arterial wall. During the procedure, a small incision in the femoral artery is made where a sheath is inserted to gain access to the blood vessels. A catheter can then be carefully snaked up the femoral artery to the aorta, from which a stent can be deployed in the correct location using the help of guidewire. This stent hooks tightly onto the cell wall and creates a sealed pathway through which the blood can now flow, diverting pressure from the weakened wall at the site of the aneurysm and greatly reducing the risk of aneurysm expansion or rupture
Figure 3: Graft deployment during Thoracic Endovascular Aortic Repair (TEVAR). Image sourced from (https://www.aorta.ca/treatment/tevar/)
Background and Project Objective
Background and Project Objective
Our project aims to design, build, test, and document an in-vitro flow loop of an aortic aneurysm consistent with real physiological parameters (i.e. flow rate, pressure, compliance). The project capitalizes on the minimally invasive nature of stent grafting to develop an innovative approach for treatment of thoracic aortic aneurysms utilizing novel grafts in 3D printed aneurysms from actual patients.
The objective will be to apply these methods for infrarenal aneurysms in the abdomen and pioneer strategies for the thoracic space as well. For those experiments, Dr. Andrew Barleben will perform the stages of Thoracic Endovascular Aortic Repair (TEVAR) on the setup. Steps include attaching a stent graft to the end of a catheter for insertion below the aneurysm site, threading the catheter to the aneurysm, securely expanding the stent graft for placement, and removal of the catheter.
Click HERE to view our project's Executive Summary
Figure 4: The final design of the model aorta. More info on design and fabrication can be found here.
Figure 5: Most up-to-date schematic for the mock flow loop
Impact on Society
Impact on Society
This mock flow loop provides assistance to surgeons in improving their techniques for TEVAR surgery. Using a risk-free in-vitro flow model, they can assure that their different methods for graft deployment and adjustment wouldn’t be fatal to the patient, quantified by how much pressure drops during the various stages of stent graft deployment.
By extending capabilities for endovascular surgery to treat aneurysms throughout the aorta, more patients can enjoy the benefits of a minimally invasive surgery method.
A video of the loop under operation can be found below.
Figure 6: Dr. Andrew Barleben performing a mock TEVAR surgery on the mock flow loop
Flow Loop Operation and Graft Deployment
Flow Loop Operation and Graft Deployment
deployment video.mp4In This Video:
Scene 1: Dr. Barleben is seen snaking a catheter through the catheter insertion point, through the abdominal opening of the aorta, about the arch, and through the ascending aorta. Live pressure readings were displayed for everyone to see.
Scene 2: The graft begins deployment, expanding out of the catheter. The graft reaches partial deployment and pressure to the branching arteries drops momentarily.
Scene 3: The graft fully expands, filling the counter of the inside of the model aorta.
Mock Flow Loop Operation
Mock Flow Loop Operation
full loop.MOVIn This Video:
Pulsatile flow is seen coming through the black descending aorta valve pouring into the reservoir. Live pressure measurements are recorded from the branching arteries of the model aorta. Measurements are physiologically accurate, reading between 80 and 120 mmHg. More on the
Component Overview
Component Overview
Figure 7: The final design of the model aorta. More info on design and fabrication can be found here.
Figure 8: Pressure sensors connected to both the flow and an Arduino microcontroller for real-time pressure measurements
Figure 9: ViVitro SuperPump. Allows physiologically accurate pulsatile flow
Figure 10: Catheter insertion point. Small silicon valves are sandwiched between 3D-printed VeroClear material so as to create a water-tight seal before and during catheter insertion
Figure 11: Compliance chamber, which simulated the ability of blood vessels to distend and expand in volume when filled
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