Category: Carotid

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Carotid

Another Carotid Body Tumor, A Shamblin I, From My Archives

These really are common in the Midwest. When I was a fellow, about one a month was done at the other Clinic. Shamblin, who ironically never went into vascular surgery, wrote the paper with the eponymous classification while a medical student.

October 16, 2008

This patient underwent a screening carotid artery duplex scan, and was found to have a 15mm mass in his carotid bifurcation. He was asymptomatic. On exam, there was a nodule that was palpable through the skin.

He was taken to the operating room with myself and Dr. Simon Wright, otolaryngologist, and we found a small discrete mass basically as anticipated on CT. The incision was along skin lines, and all the nerves were dissected using McCabe clamp. Hemostasis was maintained with sutures, clips, and a harmonic scalpel which was used to avoid transmission of electrical energy into the wound.

 

The mass gets its perfusion from multiple branches from the external carotid artery. By patiently dissection these, the tumor was dissected and removed. This was a Shamblin Type I lesion (see blog entry). The patient recovered without complication and was discharged the next day.

The panel below right shows the screening carotid duplex study which found the lesion. The CTA above shows the lesion in its typical location. The oblique axis MPR view shows the mass to have multiple vascular supply, but to be discrete and not invading the artery. The photos above show the lesion in-situ and ex-vivo.

Path revealed it to be a paraganglionoma.

Categories
Carotid techniques

Hybrid endovascular repair of proximal left common carotid artery aneurysm

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Patient is a younger man who was referred for evaluation of a left common carotid artery aneurysm that complicated Takayasu’s arteritis. He was on maintenance steroids and was asymptomatic, but over a year of surveillance, his aneurysm grew from 2.6 to 2.8cm with encroachment of the aneurysmal segment onto the origin of the LCCA which had a bovine anatomy. Treatment options included continued observation, open repair -direct or extraanatomic, and hybrid endovascular repair.

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The patient did not want to undergo sternotomy for definitive repair if less invasive options were available. Considering a subclavian to carotid bypass, the occlusion of the aneurysmal stump would be technically difficult and hazardous for future stroke. Therefore a hybrid repair with exposure of the carotid bifurcation and clamp of the internal carotid artery for cerebral protection was chosen.

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In the operating room, the carotid bifurcation was exposed via an oblique skin line incision with the C-arm oriented on the patient’s right. A table was draped off the patient’s left arm which had been prepped for brachial access for aortography. Access was taken from the distal common carotid artery with orientation of the Rosen wire down the descending thoracic aorta -this was to accomodate the nose cone of the device, a Cook 24mm AUI converter with a 12mm iliac extension. This choice of stent grafts accorded with the type of graft I would have chosen for the open repair (Dacron based), and had the appropriate size to exclude the aneurysm from the short proximal neck to the distal segment. The arteries were surrounded by inflammatory tissues and this made dissection challenging but not onerous as a redo dissection.

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The predeployment arteriogram identified fluoroscopic clues to deployment.

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In this patient’s case, the tip of the ET tube provided an excellent reference. (see above composite arteriogram).

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Deployment was satisfactory. The arteriotomy, a transverse one I had made to avoid a tear in the thickened, chronically diseased artery, was repaired with running monofilament suture after flushing. The patient did have some oozing because of being on Plavix, but a drain was unnecessary. He awoke neurologically intact and was dimissed on POD#2.

Categories
Carotid techniques

The carotid baroreptor -can it be reconstituted after carotid endarterectomy?

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While I was a site investigator for the CVRx Rheos Trial, a device that induced hypotension and bradycardia by stimulating the carotid baroreceptor with electrical energy to control resistant hypertension, I noticed that Hering’s nerve can be readily identified by accompanying arteries which show up as paired red lines. The baroreceptor complex is a pressure transducer and the maximum dP/dt can be transduced in areas of maximum curvature change. If you recall those tension maps of aneurysm rupture points, they occur in areas of maximum curvature and inflection points -wouldn’t a baroreceptor be constructed to sense pressure and change in pressure here? Hering’s nerve comes out over these areas. It struck me that most of the patients with carotid disease are hypertensive and it may be a disease cycle that occurs with stiffening of the baroreceptor, decreased parasympathetic tone, and hypertension as the output signal with subsequent vessel injury and plaque formation and worsening stiffness -a non virtuous cycle.

The nerve probably wraps around the origin of the internal carotid artery or wherever the curvature is best suited for pressure transduction. If you visualize the bulbous origin of the ICA as the belly of the guppy, the arteriotomy is made traditionally on the side facing you which is on the side and across at least half of Hering’s nerve -on the lateral surface of the guppy. If you make instead an arteriotomy on the belly of the guppy, and preserve as much of these nerves as possible, it would be theoretically possible to reconstitute a baroreceptor, maybe the dominant one (there is a sidedness to the baroreceptor strength).

There is an intriguing consequence to cutting the nerves -for example in skeletonizing the ICA for an eversion. Eversion endarterectomy done this way is associated with greater incidence of postop hypertension than standard endarterectomy (ref 1,2). The question is if the converse -if reconstituting the baroreceptor can bring decreased need for anti hypertensive medications or even hypotension and bradycardia -is true and if there is potential for applying this as therapy for hypertension as well as stroke risk reduction.

References
1. J Vasc Surg. 2012 Aug;56(2):324-33.
2. J Vasc Surg. 2001 Nov;34(5):839-45.