The Closest Thing to an Off Pump CABG -a Carotid Subclavian Bypass to Treat Unstable Angina

 

Patient is a 77 year old man with history of HTN, hyperlipidemia, former smoking, and CAD with CABGx5 and bilateral lower extremity bypasses who developed unstable angina consisting of neck and throat pain. He underwent catheterization at an outside hospital and found to have 100% LAD occlusion, a diseased, small patent left main and left circumflex (the profunda femoral artery of the heart!), 100% RCA occlusion, a patent but diseased SVG to distal RCA, and a patent LIMA graft to distal LAD but with severe plaque and near occlusion of his proximal left subclavian artery.

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He had an NSTEMI. His vitals signs stabilized in the coronary care unit and he was sent to a telemetry floor. Whenever he walked, he would get the jaw pain, and this would also occur sporadically while recumbent.

On examination, he had no left brachial pulse, only a monophonic signal there, and bounding femoral pulses where there were the origins of bilateral femoral-tibial bypasses. His radial artery pulse was diminished on the right and absent on the left. Both saphenous veins had been harvested as were arm veins for the left leg bypass.

CTA shows the left subclavian artery to be occluded at its origin.

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Heavily calcified occlusive plaque in left subclavian artery
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Arrow points to LSCA origin with plaque

Cardiac surgery, interventional cardiology, and vascular surgery were called in for consultation. Cardiology consultation (Drs. Kapadia and Shisheboor) felt, and I agreed, that the left subclavian lesion was a poor candidate for recanalization and stenting. CT Surgery (Dr. Faisal Bakaeen) and I had a long discussion regarding alternate conduits, as he had unknown radial but likely radial artery disease, and had all usable veins previously harvested. I brought up a free RIMA graft -I had worked with Dr. Daniel Swistel, in NYC as a resident, who was Dr. George Green’s protege, and as a medical student at P&S I scrubbed Dr. Green’s final cardiac case. He routinely performed bilateral ITA bypasses decades before all-arterial revascularizations were routine. I get enthusiastic talking about cardiac disease! Walking through all the options -does anyone use deep femoral vein as coronary bypass conduit -we agreed ultimately that the best option would be a carotid-subclavian bypass with plenty of backup.

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At its heart, it would be this vascular surgeon’s attempt at an off-pump single vessel CABG (above). Preparations were made with cardiac anesthesia and cardiac surgery to place an IABP (intra-aortic balloon pump) if he became unstable. For my part, the operation was straightforward, but I was going to have to go about it efficiently. I also figured that with a clamp beyond the LIMA takeoff, no significant change would occur to the coronary flow from the LIMA graft. So I hoped as I worked very deliberately. We kept him on the hypertensive side during the case.

The operation went well. The patient’s angina resolved and a followup CT showed the patent bypass feeding the LIMA and LAD.

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LIMA bypass not well visualized on coronary CTA because of the clips used in dissecting them. Perhaps we will switch to clips that are invisible to x-ray one day. 
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Composite CTA showing the bypass

His resting angina resolved. He followed up a month later and was very pleased. Moreover, he had a brachial and radial artery pulse and a general weakness of the left arm that he never complained about before lifted.

Discussion

The carotid subclavian bypass is something that really needs to be in the armamentarium of a modern vascular surgeon. Though out of print, Wylie’s Atlas (the unabridged, multivolume version) is available used through online sellers, and is useful for elucidating the anatomy which boils down to avoiding cutting the important structures -the phrenic nerve, the vagus nerve, the brachial plexus, branches of the subclavian including the vertebral artery, while cutting away muscles -lateral head of sternocleidomastoid, any part of the omohyoid, the anterior scalene muscle. And dividing the lymphatic duct if encountered. And tunneling under the jugular vein. And minding the buttery fragility of the SCA. The best technical paper out there is by Dr. Mark Morasch and it mostly deals with carotid-subclavian transposition (reference 1) but has excellent figures on bypass as well. I do both transposition and bypass, but for brevity, I prefer bypass.

This is not a unique problem, having been reported in the literature. An unusual variant of this is coronary sbuclavian steal syndrome (reference 2), which refers to reversal of flow in the LIMA bypass in the setting of subclavian artery occlusion and left arm exertion -which was not the case here, but interesting enough to mention. Here, it was a straightforward case of managing the hemodynamics. The key point of operating on such a patient was having the surety of quick response in the case of ischemic heart failure -we operated in the cardiovascular operating rooms with rows of perfusion pumps and balloon pumps and VADs and ECMOs at the ready.  Indeed, this result could not have been so straightforward and routine seeming without the combined effort and experience of the whole Heart and Vascular Institute from nursing to consultant staff.

 

Reference

  1. Morasch MD. Technique for subclavian to carotid transposition, tips, and tricks. J Vasc Surg 2009;49:251-4.
  2. Cua B et al. Review of coronary subclavian steal syndrome. J Cardiol. 2017 Apr 14. pii: S0914-5087(17)30090-4. doi: 10.1016/j.jjcc.2017.02.012. [Epub ahead of print]

Dysphagia Lusoria -a simplified approach

Arrow points to the esophagus. Tension is maintained by the tether on either side of the esophagus. By releasing one side, the tension is relieved.

The patient had been suffering with dysphagia for over a decade and had had extensive head and neck work up which found a goiter. Medical treatment of this goiter failed to relieve the lingering sensation of food getting stuck and the constant feelingof choking. It was only after a search for mediastinal sources of dysphagia that an aberrant right subclavian artery was found. 


One of the advantages of working at the Clinics (I was a fellow at the Mayo, and currently on staff the the Cleveland) is that the infrequent is common while the common is rare. Recently in clinic, I had not one but two patients with dysphagia lusoria. It was the observation of Dan Clair’s,  chairman emeritus, that by simply transposing the aberrant and yet nonaneurysmal right subclavian artery, the tension on the esophagus and trachea are relieved. Or as the dictum might go: it takes two hands to garrote someone


The question is then what to do with the stump? The natural history of the untreated stump is unknown but may be more benign than one might assume. It certainly doesn’t degenerate into an aneurysm all the time -chest CT’s are fairly common and when these are discovered, they are not usually aneurysmal like persistent sciatic arteries which present typically as aneurysms with thromboembolism. Perhaps because we don’t sit on the subclavian artery as we would on a persistent sciatic artery that these aberrant right subclavian arteries don’t degenerate. 


The old fashioned way I learned to treat these aneurysms (Kommerell Diverticula) was through a high thoracotomy and short graft repair of the aorta, replacing the origin of the diverticulum.  This is a dangerous operation for  an older, sicker, and often cachectic patient. The more recent reports involve a left carotid subclavian bypass or transposition and TEVAR after a right carotid subclavian revascularization. This second step may be unecessary if the non-aneurysmal stump proves to be benign. I don’t recommend coil embolization of the stump as mass effect of packed coils adjacent to the esophagus can cause dysphagia to recur, and this may necessitate an open resection and repair (observation, DC). 

The patient underwent a successful right carotid subclavian transposition and had immediate relief of her dysphagia for the first time in over a decade, especially because she had been told she may have been imagining the discomfort. Kudos to her physicians who ordered the CT of the chest that discovered her arch anomaly. Follow up at 6 weeks showed a stable subclavian stump and patent transposition (images above). My plan is for regular interval CT’s with increasing intervals as time passes. 

April 2016 Journal Club

Vascular Journal Club will be on April 19, 2016 at the usual location. Presenting will be:

Dr. Dimitri Virvilis –synchronous carotid and coronary artery disease

Dr. Max Wohlauer –neurorescue -please be prepared to discuss cerebrovascular anatomy

Dr. Roy Miler –vertebral translocation

 

A non-renal operation to lower blood pressure?

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Our journal club today is discussing one of the many trials that have tried to validate endovascular renal denervation to control severe hypertension. One of the devices I was on trial for back in the 00’s was the CVRx Rheos trial which stimulated the carotid sinus using a surgically placed electrode and generator. While the approval trial failed in the US, it was approved in Europe and my observation of over 30 patients who had this at my center at that time was that it was effective. So effective that I believe many patients stopped taking their pills in exchange for electrical energy -some patients required at least once a year generator changes, often more, but they had normal blood pressures and less to none of the side effects of their medications which frequently exceeded 5 agents.

I have observed that on the carotid baroreceptor, which is shaped like an aneurysm by the way, there are paired vasovasorum in the pattern seen above. The only other time I have seen paired arteries is with a nerve. The baroreceptor nerves are very hard to see, but they are there and you can find them between these paired vessels.

The observation that the baroreceptor looks like an aortic aneurysm isn’t a silly one. The area of maximal wall tension is in regions of greatest curvature change and these, teleologically, would be the shape of a baroreceptor. The stiffening of these regions with atherosclerotic plaque would decrease the signal sent to modulate blood pressure and heart rate, and create a pathologic cycle of increasing pressures in response to increased vessel stiffness and vice versa. Just saying.

I began to wonder if restoring the elasticicty of these vessels and the shape of the baroreceptor would have a lasting impact on blood pressure. The operation is eversion carotid endarterectomy with sparing of Hering’s nerve.

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The plaque can be removed without stripping the carotid sinus nerves, resulting in restoration of the sinus/baroreceptor complex.

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This would result in bradycardia/hypotension, which I have observed in a percentage of my eversion endarterectomy patients. Cutting the nerves results in hypertension, and was the subject of a paper from Montefiore (reference).

However, the proximal ICA at the carotid bifurcation was mobilized circumferentially to facilitate its transection from the CCA at the carotid bulb. During this approach, carotid sinus nerve fibers derived from the glossopharyngeal nerve and innervating the carotid body within the adventitia of the proximal ICA were routinely divided (Mehta et al.)

In that paper, hypertension was seen in 24% of patients undergoing eversion CEA with denervation compared to 6% undergoing standard endarterectomy, and as an aggregate occured for a prolonged period of time:

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The hypotension and bradycardia that I observe in nerve sparing eversion endarterectomy appears to be transient, but it is my unstudied observation that some of these patients subsequently have a lower need for blood pressure medication. This will deserve further study, but may explain the variable results of denervation procedures aiming to control hypertension. To some extent, all blood vessels are innervated and provide an aggregate signal to the CNS. Without understanding the central pathways of hypertension, the baroreceptors offer the best way of controlling blood pressure without medication like lighting a flame under a thermostat to get the building colder.

Reference

J Vasc Surg 2001;34:839-45.

 

 

 

Oblique Incisions Do Not Compromise Exposure During Carotid Endarterectomy

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I was asked to assist one of my otolaryngology colleagues in extirpating a neck tumor that encroached on the carotid artery at the base of the skull early in my career. While the operation was complex and interesting, the most impressive part of it was the complete exposure of the neck from base of skull to the base of neck that was possible with an oblique skin line incision. This challenged bias I had about “exposure,” because up to that time, I had done the mastoid process to manubrium incision along the anterior border of the sternocleidomastoid muscle. What was doubly remarkable was that the incision was invisible in followup despite curling from ear to epiglottis because it was hidden in the fold under the submandibular fat.

This patient above had his carotid endarterectomy performed with a skin line incision. He didn’t even need his beard shaved for the operation.

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The key is developing subplatysmal flaps like the kind you make with thyroidectomy. This allows cephalad and caudad exposure. More exposure means just extending the incision medially and laterally. These flaps heal well. This with retraction allows for excellent exposure of the neck.

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The other advantage is that the fat is never cut across but completely avoided if you go under it and lift it up. The incision is far less disfiguring and heals well because the forces co-apt the skin without relying on tension from the closing sutures. Preop planning with CTA and 3D virtual reconstruction confirm where the incision should be placed. But most of all, the patients appreciate not having a scar on the neck that they have to constantly explain.

Planning starts with visualizing the proximal and distal extend of plaque needed to be removed.

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The 3D reconstruction view can be “Window Level”-ed to bring in soft tissues and skin to anticipate the operative exposure.

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Experience has shown me that it is possible to avoid cutting through the fat on the neck, and what is visually the lower part of the face as much as it is the neck, but performing this oblique incision in the skin fold.

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Innominate Endarterectomy -what the Satinsky clamp is for

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The patient, a 47 year old woman, was referred for syncope, but it was much worse than that. Excessive stress, standing, and thinking hard were described as causes of her syncope. Frequent headaches and lethargy lead to inability to keep a job. Several MVA’s resulted in revocation of her driver’s license. Added to that was a two to three pack a day cigarette habit. Her cardiac workup was negative, but it was noted that her carotid duplex was notable for a left ICA occlusion and left vertebral occlusion. Blood pressure in both arms was in the 70’s systolic while in her better thigh it was 90’s. She had an open right carotid system but the flows in the common carotid were attenuated. CTA of the arch revealed severe arch disease affecting the origins of her great vessels. The innominate artery was severely diseased to its bifurcation with a small <2mm channel of flow. She had a dominant right vertebral artery that was patent, and the right ICA had moderate disease at its origin. This was in 2009, and I entertained intervention, but wasn’t all that confident that kissing stents into the innominate was all that great of an option even though there are reports of innominate interventions in the literature. I had the opportunity to perform a handful of great vessel reconstruction with Ken Cherry during my fellowship and felt that this was an ideal case for an innominate endarterectomy.

This is one of those rare and infrequent cases from vascular surgery history. The exposures is one of the grand vistas of vascular surgery. The arch, thankfully, was only calcified at the origins of the vessel and clamped well. The endarterectomy was not that much different from an aortoiliac endarterectomy with a fibrocalcific plaque and was extended onto the common carotid while the origin plaque of the subclavian was plucked cleanly. The phrenic and vagus nerves were protected. The patient was centrally hypertensive as found by a long femoral arterial line and was kept that way for the duration of the clamp. A bovine pericardial patch was applied and the sternum was closed over a mediastinal chest tube.

The recovery was impressive for the patient’s immediately improved state of consciousness, lack of lethargy, and improved cognition. She was herself impressed enough to quit smoking during that admission for good. Her right brachial cuff pressure now correlated well. She went home POD 5. When I last saw her 2 years later, she was employed and symptom free with continued patency of her repair, consistent with the earlier reports of this operation (Cherry et al. J Vasc Surg; 989;9:718-14).

The right and left carotid bifurcations usually look like this

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Maybe it’s the way the the bilateral dorsal aortas resolve into an asymmetric arch, but there is asymmetry in the carotid arteries which lets me look at a lateral carotid arteriogram and reliably predict which carotid artery it is. Image I is the usual conformation of the right ICA takeoff which may be tucked ,medially and posteriorly toward the pharynx. Image II is the typical forked appearance of the left ICA, and because it is longer and the plaque usually ends at the bend, this makes an eversion easier on that side. I began noticing this when I was on the CVRx trial applying stimulator leads on the carotids.