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Cannulation
The carotid artery of the mouse can be cannulated using the same catheters constructed for use in the femoral area. The carotid artery
cannulation should be done only on an acute basis since the compromise of cerebral circulation by occlusion of one of the carotid arteries generally results in some
morbidity to the mouse.
The carotid artery is approached through a midline incision over the trachea and throat of the mouse. Two approaches can be used. The one
most commonly employed goes along the midline separating the two muscles overlying the larynx and bisecting the muscle plane to expose the trachea itself. Dissect
laterally, usually to the animal's left side of the trachea, and the carotid artery is found lying approximately 2 mm lateral and just posterior to the trachea. Careful
dissection is required to avoid damage to the vagas nerve or the recurrent laryngeal nerve in isolating the carotid artery. A long straight area of artery is available at
this dissection site.
Three sutures are used for cannulation of the carotid artery, just as in the femoral area.
- Distal Suture:
The most distal suture (most cranial suture in this case) is placed just proximal to the carotid sinus and ligated.
- Proximal Suture:The proximal suture is placed as close to the chest area as possible and the intervening area of the carotid
artery is cleaned of adventitia.
- Middle Suture:
A third suture is placed between the proximal and distal sutures and is used to prevent or reduce blood flow when introducing the catheter.
After the carotid artery is isolated, tension is placed on the proximal 7-0 silk suture and blood is removed from the lumen of the isolated
portion of the carotid by gentle massage of the artery, pushing the blood back beyond the proximal ligature. No reflow of blood insures that the proximal ligature is tight
enough to prevent bleeding once the carotid artery has a small cut placed in it.
The catheter is introduced into the carotid artery at the incision site, approximately 2-3mm proximal to the carotid sinus. The carotid
arterial catheter needs to be approximately 14 mm long when introduced at this site to insure that the tip of the catheter will extend down the carotid artery all the way
to the aortic arch. When the animal is in the prone position with its head extended this catheter length is empirically determined to achieve placement of the catheter tip
just at the aortic arch.
Acute Experiments
 For acute experiments, the majority of the catheter or the total length of the catheter can be reduced so that
maximum catheter fidelity can be achieved when used with a conventional transducer manometer system.
The PE10/50 cannular system is probably advisable for the carotid artery as well as the femoral artery in that it
allows easier connection of the catheter within the animal to the external manometer systems.
Acknowledgement
Thomas L. Smith, Ph.D., Department of Orthopedic Surgery, Wake Forest Medical
Health Science Center, Winston-Salem, NC.
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Accute Pressure Measurements
