Imaging In-Stent Restenosis: An Inexpensive, Reliable, and Rapid Preclinical Model

Hi, I am Dr.Schwab from the STEM Cell Transplantation and Transplant Immunology Lab at Stanford University. I'm Dr.Dee. I work in the Department of Cardiothoracic Surgery at Central University.

And I'm Dr.Keno from Stanford University Cardiovascular Medicine. Today we'll show you a procedure for state implantation events. We will also demonstrate OCTs as a novel technique for in vivo imaging.

We use this inexpensive, reliable, and rapid preclinical model in our laboratory to study the development of incent stenosis. So let's get started. To begin this procedure, prepare the stent by filling the pistol with 10 ccs of saline and D air and lock it.

Next, connect the stent catheter and the pistol. When the stent is ready, the male Sprague jolly rat is anesthetized with iso fluorine and an upper median laparotomy is performed to expose the infrarenal aorta. The following steps are performed under microscopic view.

The abdominal aorta is dissected from the surrounding tissue from the level of the renal arteries down to the bifurcation. It is important to note that you do not need to dissect the aorta from the inferior vena cava. Use micro clamps to stop the aortic blood flow by placing the proximal clamp first.

Followed by the distal clamp side, branches are individually clamped. Next, the aorta is opened with a small transverse incision, not too close to the proximal clamp and flushed with heparin. Once the aorta is opened, the aortic endothelium is denuded by the passage of a two French foggerty arterial embolectomy catheter.

Remove the plastic cap from the stent and introduce the stent into the aorta position and deploy. Stent length should not be switched within the same study, depending on the stent used, apply the appropriate balloon pressure to achieve the desired diameter. To avoid pre and post stent stenosis, the diameter of the stent should not exceed the vessel diameter by more than 10%Once the stent is deployed, flush it with heparin.

Now that stent deployment is complete, switch the microscopic view to 10 x magnification. The small aortic incision is closed with 9.0 running proline sutures. Finally, the clamps are opened and the abdominal incision is closed in layers with three oh Vicryl running sutures.

To begin optical coherence tomography imaging, an a median redo laparotomy is performed to expose the infrarenal aorta, clamp the proximal aorta, and both iliac arteries. After this, perform a transverse aortic arter otomy. Next, insert the OCT catheter and forward it into the aorta.

And the light is now moving from proximal to, you Know, you can see right here. Yeah, yeah, you can see that. Oh, that's pretty cool.

With the catheter inserted, we can now begin OCT imaging. The aorta is flushed with saline and motorized pullback. OCT imaging is performed at a pullback rate of one millimeter per second.

Images are acquired at 15 frames per second. Acquired images are displayed with a color lookup table and digitally archived. Once image acquisition is complete, the arter otomy is closed using 9.0 proline running sutures.

Lastly, the abdominal incisions are closed with three oh Vicryl running sutures. Now that the OCT images have been obtained, we can begin image analysis using a light lab OCT imaging proprietary software with a rat based interface. First calibrate the system to the reflection of the OCT imaging wire.

Next, trace the lumen and stent cross-sectional areas manually at one millimeter intervals to make the calculations. The plaque cross-sectional area is calculated as stent cross-sectional area subtracted from the lumen cross-sectional area. The percent plaque area is calculated as plaque cross-sectional area divided by stent cross-sectional area.

The OCT results correlate well with histopathology histologic plaque. Cross-sectional areas are calculated as described. Histology at six weeks after stent deployment reveals intimal hyperplasia with high density of spindle shaped cells and only a few mononuclear inflammation.

Cells after six weeks, stents are completely covered with neointimal granulation tissue and the plaque cross-sectional area measures 1.3 plus or minus 0.4 square millimeters in a 2.5 millimeter stent. We've just shown you how to implant a human stent into the we order. And that OCT cell liable methods to monitor in vivo the stenosis development.

When performing this procedure, make sure to use reds weighing more than 500 grams so their abdominal AARs match the size of human coronary arteries and therefore the stent size. Remember to avoid can lab phenomenon and the vessel injury bike deployment. So that's it.

Thank you very much for watching and good luck with your experiments.