To begin, connect a multi-track angiographic catheter in the region of interest of an anesthetized catheterized sheep to a pressure transducer with a three-way stopcock. Then flush the multi-track with heparinized saline. Flip the off position on the stopcock to the syringe so that the pressure transducer and the multi-track are open to each other.
Connect the contrast injector to the multi-track centered in the abdominal IVC. Turn the knob of the contrast injector counterclockwise slowly to pull air bubbles from the multi-track until blood is seen. Then turn the knob clockwise to push contrast forward slowly into the multi-track.
Confirm when the contrast has reached the tip of the multi-track with a fluoroscope. Divide the total contrast used for the 3D angiogram by five to obtain the rate of injection in milliliters per second. Then set the rate rise to 0 in 600 pounds per square inch.
Next, to set the C-arm to the pre-programmed mode, click the Program button, then press the 3D-110 8"button. Move all objects and people away from the front or sides of the table. Click on button 3 on the control panel to initiate the C-arm.
Position the target at the center of the xy plane. Click button 4 on the control panel to move onto the second program. Then adjust the height of the table to center the region of interest.
Next, press button 5 to take the test image. click on the Confirm Conditions icon, followed by Start to pretest the C-arm's range of motion. Use the middle acquisition pedal to initiate the program and take a 3D rotational angiogram.
Simultaneously, measure and record the mean pressure of the target region. Connect a pressurized saline bag to a 9 French sheath. Allow it to flow until the sheep has received a bolus equivalent to 20 milliliters per kilogram.
Record the intravascular pressures of the target region every minute while the bolus is flowing. Perform the second 3D angiography with concurrent intravascular pressure measurement. Once imaging is complete, press the number 77 and hold the Start button to place the C-arm back in its pre-programmed to position.
Remove the multi-track angiography catheters and Rosen wires from the sheep. Then remove both sheaths. Apply pressure with a hemostasis patch over the insertion sites for at least seven minutes to control bleeding.
For data analysis, export the original raw 3D angiography data from the angiography imaging software in a DICOM file format. Launch the DICOM Viewer software. Then drag and drop the 3D angiography file into the Viewer to open.
Select the 3D Multiplanar Reconstruction tool to generate a 3D reconstructed view of the angiography data. Three distinct 2D views from the axial, sagittal, and coronal planes can now be seen. Now adjust the placement and orientation of the target region in the sagittal and coronal planes to place the target region at the center.
Use the Hand tool to rotate the direction of the reference lines on each page. With the Pencil tool, outline the vessel wall in the axial view of the target region. The software will automatically calculate and show both the area and perimeter of the region in the middle of the axial view.
The intravascular pressures of sheep with and without PTFE grafts were obtained. A change in circumference was seen in the native sheep in response to bolus. The native sheep vessels were more compliant and distensible than the PTFE grafts.
