The overall goal of this procedure is to create a reliable model of cerebral venous hypertension in the adult mouse. This is accomplished by first dissecting the common carotid artery and the external jugular vein to expose both vessels. Next, the anastomosis is prepared by applying temporary clips and ligatures.
Then after temporarily occluding each of the vessels, a matching pH otomy and arter otomy are performed. Finally, a continuous 11 zero suture is run to create an end to side bypass between the common carotid artery and the external jugular vein. Ultimately, results can be obtained that show cerebral venous hypertension in the mouse through enlargement of the mouse eye, 24 hours after surgery and through elevated sagittal sinus pressure two, three, and four weeks post-surgery.
Usually individuals new to this method will struggle because of the challenging technique required for the anastomosis and the Dimi pH anatomy of the vessel symbol. After anesthetizing the mouse with 5%ISO fluorine and administering 0.15 milliliters of buprenorphine for pain management. Verify the level of anesthesia by pricking the mouse's paws with the mouse and dorsal recumbent and adhesive tape of fixing its limbs.
Remove the hair from the neck and the upper chest to keep the mouse hydrated. During the surgical procedure, subcutaneously inject 0.2 to 0.4 milliliters of 0.9%saline. Begin by making a horizontal midline cervical incision across the lower neck area of the mouse.
After deepening the wound, use a traction suture to elevate the salivary glands and cervical soft tissue. Next under the microscope. To avoid excessive traction and thrombosis, expose the right external jugular vein or EJV lateral to the sternal CTO mastoid muscle, or as cm.
Carefully dissect the right EJV along its course from the clavicle to the base of the skull, coagulate and divide any branches. To prepare an adequate length for temporary clip placement and anastomosis lateral to the trachea and medial to the SCM, explore the common carotid artery or CCA. It should be carefully exposed from the clavicle to just beyond its bifurcation into the external and internal carotid arteries.
To prepare the anastomosis begin by using 10 zero nylon to ligate the CCA just proximal to its bifurcation. Next, as close to the clavicle as possible, apply a temporary clip over the proximal CCA. Once the flow has been interrupted, transect the artery just under the bifurcation ligature and use saline to wash out any remaining blood inside the lumen.
Avoid bipolar coagulation here since thermal injury to the artery wall could put the future anastomosis in jeopardy. Next, to improve the visibility of the edges of the EJV, use a blue pen to mark the medial wall along the course of the planned V otomy. Then use a 10 zero suture to ligate the distal end as codal as possible, and apply a temporary vascular clip to the proximal end as cranial as possible to avoid thrombus formation with a fine 30 gauge needle and 0.5 milliliter syringe.
Make an initial aperture over the marked area of the EJV and immediately use saline to irrigate the lumen using micro scissors to make a sharp and neat cutting edge, extend the ven otomy until the length. That's about two to three times the diameter of the CCA. Approximate the end of the CCA to the EJV.
Then make a side cut incision in the donor end of the CCA to adjust the diameter to the length of the size of the V otomy for the CCA to EJV and to Cy anastomosis. Start by using 11 zero monofilament nylon to suture the medial wall in a cranial coddle direction. Each interrupted or continuous stitch should be placed from outside in the venous wall first, and then from inside out the arterial wall.
If using continuous stitches as a final step, tighten the sutures. Next, repeat the procedure from coddle to cranial with the lateral wall from outside in the arterial wall first, and then from inside out the venous wall. Then remove the temporary clip from the vein and next from the artery.
Arterial blood should flow into the EJV with little or no oozing from the anastomosis, and any minor bleeding should stop on its own. It's best to avoid using compression to prevent thrombosis of the delicate vein. Once Pulte flow through the anastomosis is confirmed and no apparent bleeding is observed, use saline to irrigate the surgical field and six zero nylon suture to close the cervical incision.
After the procedure, monitor the mouse in an individual cage until it is fully awake. Able to hold a sternal position and it is keeping a proper heart rate and respiratory frequency the following days. Check the incision for swelling, infection, pain, or dehiscence, and provide analgesia as needed.
A successful outcome for the procedure demonstrated. Here is a patent arterial venous fistula that induces venous hypertension in the mirroring brain to validate the model. The intracranial venous pressure in the sagittal sinus of the mice was initially measured two, three and four weeks after surgery with six mice assigned to each time group as shown here.
Postoperative two week sinus pressure assessed at 8.8 plus or minus 1.2 millimeters. Mercury was significantly higher than the 4.7 plus or minus 1.4 millimeters Mercury measured in the three week post-surgery group and the four week post-surgery assessment of 3.9 plus or minus 0.6 millimeters mercury. However, the complex technique required to measure the sinus pressure is not necessary to ensure fistula, patency and venous hypertension on a regular basis.
Instead, the desired outcome can be checked using one of two methods. The first directly examines the patency of the fistula at the end of the surgical procedure in two ways, using jeweler's forceps to temporarily obstruct the EJV cranial to the anastomosis area will cause the EJV to immediately balloon out as shown here. Because this point is now the only outflow of blood coming from the CCA.
The second fistula patency test is performed by occluding the vein graft distal to the anastomosis and slowly emptying or milking it. Once the occlusion is released, a patent anastomosis should quickly refill the emptied segment. The second method for ensuring fistula, patency and venous hypertension is by identifying clinical signs of venous hypertension.
For example, if the model is working, the mouse's eye may noticeably enlarge 24 hours after surgery due to compromised venous drainage of the head and neck as shown here. Although both eyes enlarge after surgery, the phenomenon is more prominent on the operated side. After watching this video, you should have a good understanding of how to perform successfully.
This technically demanding anastomosis that provides a reliable cerebral venous hypertension model in the adult mass.
