Category: acute mesenteric ischemia

Categories
acute mesenteric ischemia chronic mesenteric ischemia complications CTA hybrid technique imaging techniques Technology visceral malperfusion

Abdominal Stroke Alert!

It is a rare day that passes without the announcement of a stroke alert at CCAD. A reflex arc of activity is initiated, as time becomes the critical metric of success. Patients with strokes have a limited window of time to reverse the effects of the arterial occlusion, and the whole hospital is organized around getting the patient into the angiographic suite to open up blood vessels. If you watch it happen, it is the pinnacle of modern medicine, to achieve what only a decade ago was deemed unachievable. It was built around a foundation laid by cardiologists for heart attacks -the STEMI alert. The teams practice like racing pit crews with a stopwatch to get a patient from the emergency room, to CT scan, to angio suite. A long time ago, as a young surgeon, I had to work hard to get institutional support of ruptured AAA and cold legs. Vascular surgery has traditionally struggled to get recognition for its patients, their diseases, and its work, which is nothing less than the most important safety net for any large general multi-specialty hospital, critical infrastructure like oxygen plumbing and backup generators. As I transition to that weird designation of mid-career surgeon (please don’t call me a senior surgeon), I have also appreciated that Steve Jobs aphorism about good artists copying, great artists stealing. It’s only stealing if you don’t give credit. Here is what I borrowed from the neurologists.

Acute mesenteric ischemia is an abdominal stroke. Use it in your conversations with other people as you speed your patients way into the angio suite. The reflex arc is in there. For the emergency department, the operating room, and all the physicians, acute mesenteric ischemia sounds like tummy trouble, but abdominal stroke brings sudden clarity to conversations like:

“Well, you’re in line behind a gallbladder and a cystoscopy. Is the patient NPO?”

Me: “It’s an abdominal stroke. We literally only have a few hours before the patient dies…”

“I’ll bring the backup team in!”

The patient is a middle aged man with risk factors of NIDDM and prior history of DVT who developed severe mid-abdominal pain at 5pm. He came to the ED at around 11pm and had a general surgery consultation who ordered a CT Angiogram showing SMA occlusion (pictured below).

Acute Mesenteric Ischemia case presentation

Acute Mesenteric Ischemia case presentation (1)
Heparin was started, and at 11:30, vascular surgery was consulted. The patient had a soft, doughy texture to his abdomen, but great pain with palpation -classic pain out of proportion to the exam. Determining the patient to have acute mesenteric ischemia from a thromboembolism, I took the patient to our hybrid angiographic OR suite with the plan for arteriography, possible open thrombectomy, and exploratory laparotomy.
Arteriography from femoral access showed an occlusion of the SMA beyond the middle colic artery, a typical pattern for an embolism that occurs when embolism lodges distally and propogates proximally (image below).

Acute Mesenteric Ischemia case presentation (2)
I got Glidewire access into the ileocolic terminus of the SMA, exchanged for a Rosen wire, over which I placed an 8F sheath into the proximal SMA. This was a rather large sheath meant to catch thrombus as I suctioned it out with a 6F Penumbra catheter. This is another technique I borrowed from the neurointerventionalists. Whenever a stroke alert is going on, curiosity drives me to peak in and see what marvelous gadget or gewgaw they are using, and I was impressed by how efficiently the neurointerventionalists were able to get to the smallest thrombus in the furthest branch vessels. I was prepped for open thrombectomy, consented for bypass if necessary, but having experience in suctioning clot through single catheters and sheaths, I thought the simple design of the Penumbra and its efficacy in the cerebral system could easily translate into the mesenteric.The problem with open thrombectomy is the inability to see if you have cleared thrombus from all the branches unless you do an arteriogram after you’ve completed your procedure. This may be a significant contributor to the 20-30% bowel resection rate that occurs on second look laparotomy in my old paper and in the literature since its publication.

The Penumbra was effective in removing much of the fresh thrombus, but I was also cognizant of the fact that pulling out the catheter will draw clot into the 8F sheath that did not make it into the catheter. I placed a wire, and removed the sheath to expel much of the bulky thrombus (picture below).

Acute Mesenteric Ischemia case presentation (3)

The completion angiogram (below) doesn’t show the intermediate angiograms showing thrombus that embolized to other arteries as I manipulated the catheters and thrombectomized -I was able to successfully retrieve these with selective catheterization, another neurointerventional series of maneuvers that I have successfully borrowed.

Acute Mesenteric Ischemia case presentation (4)
After being satisfied with the completion, I removed the sheaths and explored the abdomen finding this segment of infarcted small bowel (next image).

Acute Mesenteric Ischemia case presentation (6)
There was no question in my mind that there would be some dead bowel based on the time course described by the patient. Despite my excitement about calling for GIA staplers -I am general surgery boarded- I called in the general surgeons for their help in resecting and anastomosing this segment of bowel. They would be the ones taking the patient back for any second look laparotomy, although in this patient, I determined that there would likely be no need. After the anastomosis was completed, I did a Wood’s Lamp examination (pictured), which is accomplished with a black light after giving the patient an ampule or two of Fluorescein.

Acute Mesenteric Ischemia case presentation (7)
The bowel had a splotchy fluorescence pattern which is typical of ischemia-reperfusion. This is where you have to ask the anesthesiologist and any critical care specialist who follows -no pressors please! Edema won’t kill an anastomosis as badly as ischemia will, and the gut is as sensitive to norepinephrine as are the toes. Workup in the hospital including echocardiography and CTA of the entire aorta failed to reveal a proximal source or cardiac shunts or thrombus. The patient recovered and has recently followed up, eating well, and tolerating his anticoagulation which he will be on for life.
I sent out the pictures to my neurointerventional friends with some glee, but also with the purpose of informing them that in the case that the vascular surgeons become incapacitated or quarantined due to the COVID-19 pandemic, their skills would be recruited in the care of an abdominal stroke -a blood vessel is a blood vessel.
Acute mesenteric ischemia should be the first thing on everyone’s differential of sudden onset abdominal pain because of its time dependence, yet it does not have the same resonance to the unfamiliar as abdominal stroke. Survival is dismal when too much time and intestinal death has occurred. When associated with the stroke alert concept, it translates into processes already in place throughout the hospital and it becomes natural for everyone to appreciate the urgency of treating abdominal stroke. This is the system adopted by Roussel et al. in France, where they have regionalized care of intestinal stroke. They report mortality rate of 6.9%, which is in a selected population, but significantly lower than the traditionally reported 30-60% mortality.

I am still an advocate of an open approach, especially when angiographic resources are unavailable, and every trainee needs to be able to describe the exposure of the SMA, and management of acute mesenteric ischemia. Hopefully, everyone will appreciate the urgency of all the various ischemic conditions manifest in the peripheral circulation, but rebranding them as a stroke (leg stroke, hand stroke, intestinal stroke…) is helpful. Finally, there is no survival with dead bowel -it must be found through exploration and resected.

Reference:

Roussel A, Castel Y, et al. Revascularization of acute mesenteric ischemia after creation of a dedicated multidisciplinary center. 2015 Nov;62(5):1251-6. doi: 10.1016/j.jvs.2015.06.204.

Categories
acute mesenteric ischemia aortic dissection bypass chronic mesenteric ischemia complications ruptured AAA taaa tbad techniques TEVAR thoracabdominal aortic aneurysm training type b aortic dissection visceral malperfusion

Life imitates social media: a ruptured type V thoracoabdominal aortic aneurysm or IT saves a life

ARTERIAL (2) (2)
Type V TAAA Rupturing into Right Pleural Cavity

It was only last month when I came across a post of an aortic aneurysm in a difficult spot (link) and I couldn’t help chiming in some comments. Reading it now, I sound insufferable, because I wrote,

“Depends on etiology and patient risk stratification. Also assuming aneurysm goes to level of SMA and right renal artery origins and involves side opposite celiac. Options depending on resources of your institute: 1.Open repair with cannulation for left heart bypass and/or circulatory arrest 2.Open debranching of common hepatic, SMA, R. Renal from infrarenal inflow and then TEVAR 3.FEVAR from custom graft from manufacturer on protocol 4.Parallel grafting to CA, SMA, R. RA with TEVAR 5.Surgeon modified FEVAR 6.Open Repair We would have a multidisciplinary huddle around this patient -Vascular, Cardiac Surgery, Cardiology, Anesthesia, and ID (if needed) to help choose. Be ready to refer to a center with more resources -including prepping patient for transfer and imaging -including uploading images to the cloud for transfer with patient’s permission. More info please”

More Info Please, Indeed

The post I commented on was of a saccular aneurysm in the transdiagphragmatic segment of aorta. Ironically, only a few weeks later, I got called from hospital transfer center about a patient with a leaking aortic aneurysm, a type V thoracoabdominal aortic aneurysm as it turned out, from an outside hospital, needing urgent attention, and we accepted in transfer based on the conversation I had with the tranferring physician. And that was the problem -usually in taking these inter-hospital transfers, you have to pray that the precious CT scans come along with the patient burned correctly onto a CD-ROM. You can buy and watch a movie in 4K resolution over the internet -about 4 gigabytes, but a patient’s CT scan which is about 200 megabytes -because of various self imposed limits, overly restrictive interpretations of laws, and lack of computer skills, these life saving images get transferred on CD in 2019. That last time I purchased a CD for anything was over 15 years ago.

An Interested Party

The technical solution –to use the internet to transfer critical life saving information between hospitals – came about when our IT folks took an interest in my quarterly complaint email about using the newfangled internet for sharing files. After mulling various solutions ranging from setting up a server to using commercial cloud solutoins, we came upon the compromise of using our internal cloud with an invitation sent to the outside hospital. I would send this invitation to upload the DICOM folder of the CD-ROM to an outisde email address. It was simple and as yet untried until this night. “Would the patient agree to have his CT scan information transmitted to us electronically?” I asked the other physician. He assured me that the patient was in agreement.

It Takes Two to Tango

Of course, being able to transfer these pictures requires a willing partner on the other side, and the referring physician made it clear he did not have the technical expertise to do so. It took a bit of social engineering to think about who would have that ability. Basically, aside from myself, who spend all their time in dark rooms in the hospital in front of giant computer monitors? The radiologists! I got through to the radiologist who had interpreted the report and explained the simple thing I needed. Gratefully, he agreed, and I sent him a link to our cloud server. I explained to him, “When you receive this, clicking the link opens a browser window and then you open the CD-ROM and find the DICOM folder and drag and drop it on the browser window.” The 200-500 megabytes of data then get sent in electronic form, as it was meant to in 2019.

The Internet Saves a Life

The brutal truth is that in locking down a computer system, many hospitals make it impossible to even load an outside CD-ROM, creating many self imposed barriers to care. Thankfully, at CCAD, we were able to work together to find a secure solution. With the CTA on our servers, I was able to review the study within 15 minutes of accepting the patient, and arrange for the right team to be assembled, and confirm that we had the right material (stent grafts) for treating the patient. When the patient arrived, OR was ready to go, saving hours of time that normally would have been required if the CT scan had to be reviewed from the CD-ROM that came with the patient. Sometimes, the CD-ROM does not come, and in a critical situation, the CTA has to be repeated with some risk to the patient for complications of the contrast and radiation.

What to Do

The patient had a 8cm sphere shaped aneurysm arising in the transdiagphragmatic aorta, leaking into the right pleural cavity.

Screen Shot 2019-06-19 at 9.29.15 PM

The patient was otherwise a healthy middle aged man with risk factors of smoking and hypertension. The centerline reconstructions showed the thoracic aorta above the aneurysm to be around 20mm in diameter and same below, with the celiac axis and superior mesenteric artery in the potential seal zone of a stent graft. The only plaque seen was around the level of the renal arteries and was focal and calcified. Looking at the list I had made as a comment to the Linked-In post, I realized that I really only had one viable option.

ARTERIAL (10).jpeg

Open repair, usually the most expeditious option, was made challenging by the right hemothorax, making a left thoracotomy hazardous if the lung had to be deflated. Cardiopulmonary bypass would have to be arranged for, and that adds a metabolic hit that greatly raises the stakes. Of the endovascular solutions, the only viable option was TEVAR to exclude the rupture and debranching of the celiac axis and superior mesenteric artery. To those who would advocate for parallel grafts, there was no room in the normal 20mm diameter aorta. And branch systems for rupture are some time in the future. Also, the patient was becoming hypotensive. So the planned operation was first TEVAR to stop the bleeding, and then open surgical debranching. A hybrid repair.

plan sketch.PNG

The smallest stent graft we have is a 21mm graft, but it would not be suitable for this aorta. In practice, the normal aorta is quite elastic and will dilate much more than what is captured on a CTA. The next size we have is 28mm graft and I chose this to exclude the rupture, which was done percutaneously.

TEVAR angio.png

As seen below, the graft excluded the celiac and SMA. Late in the phase of the final aortogram (second panel) there was an endoleak that persisteed despite multiple ballooning. The timing suggested the intercostals and phrenic vessels contributed to a type II endoleak, but it was concerning.

postangio.png
Find the Endoleak

The bypasses were sent from the infrarenal aorta to the common hepatic artery and the SMA close to its origin, and the origins of the celiac axis and SMA were clipped. The bypasses were then done with a 10x8mm bifurcate Dacron graft originally for axillofemoral bypassing. It had spiral rings which I removed at the anastomosis and this resulted in a kink at the closer bypass. Usually, I loop this for iliomesenteric bypass but there was not enough distance from the infrarenal aorta. I have to add a little trick I modified from my pediatric surgery experience as a resident -a Heinecke-Mikulwicz graftoplasty:

IMG_2646.JPG

This worked to relieve the kink as evidenced on the aortogram above. After closing the laparotomy, I placed a chest tube in the right chest. The patient had a course prolonged by a classic systemic inflammatory response syndrome, with fevers, chills, and leukocytosis. He bled for a while but stopped with correction of his coagulopathy. All blood cultures were negative, but a CT scan was performed out of concern for the endoleak, and the possibility of continued bleeding.

postCTA.jpg

No endoleak was detected as the sac was fully thrombosed. There was a consolidation of the blood in the right chest, but it resolved with fibrinolytic therapy.

Discussion

This case illustrates several points I have been making on this blog.

  1. Hybrid repairs are not some kind of compromise but the full realization of a complete skill set. When students ask me how to judge a training program, one of the best metrics is how frequently are hybrid operations performed. It means either the endovascularist and open surgical operator are in complete synchrony or there are individual surgeons competent in both open and endovascular surgery. Hybrid operations, rather than being a compromise, are an optimization.
  2. Time -Laying the stent graft across the celiac and SMA origins starts a warm ischemia clock. The liver and intestines, in my reckoning, should be able to tolerate the 2 hours of work to get the bypasses working. Cardiopulmonary bypass may give you less ichemia but at the metabolic cost of the pump time. These negative factors add up, but were surmounted by the fact that early control of hemorrhage was achieved. Stopping the bleeding and restoring flow are the core functions of vascular surgery.
  3. Planning and preparation. The ability to see the CT images and prepare the teams and materiel before the patient transferred was lifesaving. This is where our IT gets credit for responding to a critical need and formulating a solution that meets internal policies, external regulations, and saves a life. It illustrates so many opportunities particularly with electronic medical records and their processes which focus more on documentation for billing. A discharge summary should be multimedia like this blog post and it should be normal and easy to generate. And finally, as clinicians, we should mind technology with as much attention as we give to the latest medical devices and techniques.
Categories
acute mesenteric ischemia AIOD aortoiliac occlusive disease (AIOD) chronic mesenteric ischemia CTA PAD techniques visceral malperfusion

When good enough is better than perfect: a case of end stage visceral segment aortic occlusive disease

The patient is a woman in her 60’s who self referred for complaint of abdominal pain, weight loss, and rest pain of the lower extremities. She is a 40 pack year smoker and had severe COPD, hypertension, congestive heart failure with mitral regurgitation, chronic kidney disease stage IV, and ischemic rest pain of the legs. She had a 30 pound weight loss due to severe postprandial abdominal pain. She had bloody stools. Her kidney function was worsening, and dialysis was being planned for likely renal failure but she was against dialysis. She had consulted several regional centers but was felt to be too high risk for surgery and with her refusal of dialysis, would be a high risk for renal failure and death with intervention. Physical examination revealed weakened upper extremity pulses, and nonpalpable lower extremity pulses and a tender abdomen. In clinic, she developed hypoxia and dyspnea and was admitted directly to the ICU.

preop-cta

CTA (above) revealed severely calcified atherosclerotic plaque of her visceral segment aorta occluding flow to her mesenteric and renal arteries and to her leg. The right kidney was atrophic. The left kidney had a prior stent which looked crushed. The infrarenal aorta was severely diseased but patent and there were patent aortic and bilateral iliac stents.

Echocardiography revealed a normal ejection fraction of 60%, diastolic failure,  +2 to+3 mitral regurgitation, and pulmonary artery hypertension. She did respond to diuresis and stabilized in the ICU. Intervention was planned.

Options that I considered were an extranatomic bypass to her legs and revascularization from below. I have come across reports of axillo-mesenteric bypass, and I have performed ascending and descending thoracic aorta to distal bypass for severe disease, but concluded, as did the outside centers, that she was a formidable operative risk. Also, there was a high likelihood of great vessel occlusive disease. Looking at her CTA, I felt that she needed just a little improvement in flow -not perfect but good enough. The analogy is like drilling an airline through a cave-in. Also, her left kidney gave a clue -it was normal sized and survived the stress test of a contrast bolus for the CTA without dying. A discussion with the patient green lighted an attempt -she understood the cost of failure but did not wish to linger with this abdominal pain.

Access for intervention was via the left brachial artery. Aortography showed the severe stenosis at the origin of the SMA and the nearly occlusive plaque in the visceral segment aorta.

preintervention-aortogram

The plaque was typical of the coral reef type, and had an eccentric channel that allowed passage of a Glidewire. Access into the left renal artery was achieved. Its stent was patent but proximally and distally there were stenoses; this was treated with a balloon expandable stent. The path to it was opened with a balloon expandable stent to 8 mm from femoral access. This was the improvement the renal needed. A large nitinol stent was placed from this access in the infrarenal aorta when severe disease above the iliac stents was encountered.  The SMA was then accessed and treated with a bare metal stent.

post intervention.jpg
Renal stent was reaccessed and ballooned in this pentultimate angiogram

Her creatinine improved, as did her intestinal angina. She was discharged home. She later returned a month after the procedure with complaints of nausea and vomiting and right lower quadrant abdominal pain and was discovered to have an ischemic stricture of her small bowel. This was removed laparoscopically and she recovered well. She recovered her lost weight and now a year and a half later, remains patent and symptom free.

Discussion: Dr. Jack Wiley includes in the preface to his atlas of vascular surgery the words of Dr. Joao Cid Dos Santos, the pioneer of endarterectomy techniques, “Vascular surgery is the surgery of ruins.” And in that context, good enough is sufficient.

 

Categories
acute mesenteric ischemia chronic mesenteric ischemia mesenteric aneurysm mycotic aneurysm

Visceral Mycotic Aneurysm Treated with Resection and Revascularization

Preop CTA_1

Sometimes the best conduit is no conduit.

The patient presented with abdominal pain and fevers which was initially diagnosed as a urinary tract infection. He is an older man with a prosthetic aortic valve and prostatic cancer who had a Foley catheter for several weeks leading up to a prostatectomy. Antibiotics relieved his abdominal pain. Echocardiogram revealed aortic valve vegetations. A CT scan revealed a mycotic mesenteric aneurysm and vascular surgery was consulted.

Preop CTA_2Preop CTA_5

Examination revealed moderate cachexia and a soft abdomen. He was taken to the operating room for resection of aneurysm. Laparotomy revealed a mass in the small bowel mesentery root. The aneurysm had moderate but not excessive amounts of inflammation.

IMG_4649

The CTA had shown the superior mesenteric artery to be patent above and below what was likely an embolized vegetation (see white arrows in all images).

The treatment goal was aneurysm resection with an intraoperative determination of need for revascularization. His thighs were prepped for possible saphenous vein harvest and cryopreserved artery was available.

Resection revealed the artery to be infected. There was good backbleeding from the distal SMA.

IMG_4653

The handheld Doppler signals in the distal segment of SMA were excellent, corresponding to the viable bowel, but the patient’s cachexia and relative inanition concerned me for future bowel ischemia complicating his planned redo aortic valve replacement and subsequent prostatectomy.

But before I embarked on vein harvest, a simple maneuver determined my next step. I brought the distal SMA to the proximal SMA and found there was enough laxity to simply anastomose both to each other.

IMG_4654The flows were now excellent in the SMA. The patient recovered uneventfully, requiring no subsequent bowel resection. He then had his redo-aortic valve replacement from which he recovered well from and ultimately soon after had his prostatectomy.

Treatment with antibiotics without resection is not a good option as the majority of these rare aneurysm go on to rupture if left unresected. A frequently cited article by Drs. DeBakey and Cooley from 1953 (ref 1) and other subsequent articles show success with simple resection. While cryografts and saphenous vein grafts are subject to infection, they can be used safely in this setting, but the best conduit using no conduit. Often, aneurysms start at a small nidus and not only expand but elongate, given an opportunity to repair aneurysms primarily.

Reference

  1. DeBakey ME, Cooley DA: Successful resection of mycotic aneurysm of superior mesenteric artery: case report and review of literature. Am Surg 1953;19:202-212.
Categories
acute mesenteric ischemia chronic mesenteric ischemia techniques

The inferior mesenteric artery is a poor target for revascularization in chronic mesenteric ischemia

Preop CTA.jpg

The patient was referred to me after having undergone an intervention for chronic mesenteric ischemia. She is over 70 years of age and had lost over thirty pounds in 3 months due to severe abdominal pain with eating. A month prior to seeing me, she had undergone arteriography at an outside hospital and was found to have occlusion of her celiac axis (CA) and superior mesenteric artery (SMA) with a small but patent inferior mesenteric artery. Attempt at recanalization, done from left brachial access, of the SMA was abandoned after the patient started having pain, and the inferior mesenteric artery was accessed and stented with a balloon expandable stent. Despite the stent, the pain persisted. On examination, she was cachectic, weighing about a hundred pounds, and had moderate to severe pain with abdominal palpation. CT angiography (shown above) showed a chronically occluded CA and SMA and a patent stent to the IMA.

After discussion with the patient about the possibility of a bypass, we decided to proceed with diagnostic arteriography and an attempt at recanalization. When planning these, I always try to come from the groin first as most of the time I am able to revascularize from below. I try to avoid 6F sheaths in the arms of thin cachectic patients -women especially where the brachial artery is likely the same diameter as a 6F sheath. The only downside about coming from below is that it is technically challenging and the stent comes off at a higher angle than the SMA typically has in situ.

The image below shows the procedure:

SMA intervention.jpg

The series of images shows the initial aortogram and access. The superior mesenteric artery has a stenosis at the origin, with an area of post stenotic dilatation or small aneurysm, which occludes beyond the first three branches of the SMA. The IMA fails to feed the bowel -the later phases not shown shows filling from the SMA segment to the CA and ileal branches.

The key step to this procedure is in getting “deep” access with a wire -in this case a floppy Glidewire, which I used to cross the occluded SMA. There is feedback from the tip which occurs if you spin it without a torque device. The wire has the quality, a feature really, of being tacky when dry, allowing for a great deal of coaxial spin with your first two fingers and your thumb. The tip transmits information about what it is crossing as you spin it -this is something that is hard to teach at first, but is gained largely through experience, but I learned it from Dan Clair over a decade ago when he barked at me to get rid of the torque device (“a tool for babies!”). The tip will go where it should if you spin, not push.

Once the wire is buried, a suitable catheter that tracks well is brought across the occlusion. Again, while there are many catheters that can do this, the Glide Catheter is suitable again from spinning across an occlusion over the wire that would push out the lowest profile and equally hyrdophillic catheters. Once the catheter is buried, a suitably stiff wire (in this case a Rosen wire) should be brought across -this widens the arc created by the wire as it goes up and over the SMA origin and allows for delivery balloons and stents. Using the balloon-piton technique (a requisite for FEVAR), the sheath is brought into the SMA, securing access into it.

The occlusion in the mid-SMA ballooned nicely and did not require a stent -a nonocclusive dissection is seen but I chose not to treat this as placing a stent is likely to cause as many problems as solve and the dissection is in line with flow. The origin was stented with a balloon expandable stent -having the patient awake is useful in determining if the stent is “big enough.” Final arteriography in two planes is shows below.

post angio.jpg

Gratifyingly, the entire mesenteric system in the CA (foregut) and SMA (midgut) lit up. I admitted her for observation as I have seen patients develop bowel infarction with reperfusion which may be due to embolization but I think just as likely due to edema. Food needs to be reintroduced slowly as there maybe metabolic consequences to rapid refeeding. Her baseline lactate was 2.6mMol/L but came down to 0.8mMol/L the next day. Her other labs were normal. Her pain remitted and she was able to tolerate a regular diet by postoperative day 2.

Discussion: 

Mesenteric ischemia is a particularly morbid condition. When it presents acutely, there is a high mortality rate (ref 1). Revascularization in good risk individuals is still bypass surgery (ref 2,3). The inferior mesenteric artery offers a dismal revascularization target for this reason -while the artery will remodel and dilated in the setting of mesenteric ischemia, its orifice from the aorta does not and is usually no more than 1-2mm from birth to adulthood. Also, while the large bowel will get perfusion from the IMA, and the foregut may get collateral flow from collaterals fed from the middle colic via the Arc of Riolan, the midgut does not get sufficient flow from from the IMA because it requires the longest path to fill the ileal and jejunal branches. The development of atherosclerosis in the aorta further complicates attempts at stenting. Despite this, it is still attempted (ref 4) and in 4 patients was successful at relieving pain for short periods of time, with one patient requiring eventual bypass despite characterization as “high risk.” It is a reflection of how poorly this vessel does with intervention that this 4 case series is the largest in the literature.

The analogy to IMA stenting in the legs is stenting of a heavily diseased profunda femoral artery in the setting of critical limb ischemia with femoropopliteal occlusive disease. It is occasionally successful in the short term, but will only delay the inevitable operation. There are no low risk patients with severe weight loss due to mesenteric ischemia. Aggressive intervention offers a path of survival for these patients, and but long term results are only possible with bypass.

References

  1. Park WM, Gloviczki P, Cherry KJ Jr, Bower TC, Panneton JM, Schleck C, Ilstrup D, Harmsen WS, Noel AA. Contemporary management of acute mesenteric ischemia: factors associated with survival. J Vasc Surg. 2002;35(3);445-452.
  2. Park WM, Cherry KJ, Jr, Chua HK, Clark RC, Jenkins G, Harmsen WS, et al. Current results of open revascularization for chronic mesenteric ischemia: a standard for comparison. J Vasc Surg. 2002;35(5):853–859.
  3. Kasirajan K, O’Hara PJ, Gray BH, Hertzer NR, Clair DG, Greenberg RK, et al. Chronic mesenteric ischemia: open surgery versus percutaneous angioplasty and stenting. J Vasc Surg. 2001;33:63–71.
  4. Wohlauer M, Kobeiter H, Desgranges P, Becquemin JP, Cochennec F. Inferior Mesenteric Artery Stenting as a Novel Treatment for Chronic Mesenteric Ischemia in Patients with an Occluded Superior Mesenteric Artery and Celiac Trunk. Eur J Vasc Endovasc Surg. 2014;27(3):e21-e23.
Categories
acute mesenteric ischemia aortic dissection tbad techniques TEVAR type b aortic dissection visceral malperfusion

Acute Aortic Syndrome Unit -TBAD with SMA Dissection and Thrombosis with Acute Mesenteric Ischemia

Figure SMA thrombus with dissection

The figure above shows the summarizes the problem that brought the patient to his local hospital and triggered his transfer to our acute aortic syndrome unit. The concept is that all chest pain of cardiovascular origin gets intake through a vast intensive care unit staffed by cardiovascular intensivists. Stabilization, workup, transfer to operating room or interventional suite all happens in an ICU that encompasses almost a city block.

The patient is an older middle aged man with sudden onset of back and abdominal pain. He was on coumadin for a prior SMV thrombosis and treatment for a ruptured appendicitis -antibiotics with plan for staged appendectomy. CT at his local hospital revealed a type B aortic dissection (TBAD) that extended into his superior mesenteric artery.

Bovine arch in 3DVR view on TeraRecon Aquarius reconstruction.
Bovine arch and TBAD in 3DVR view on TeraRecon Aquarius reconstruction.
The aortic dissection terminated in the infrarenal aorta. The celiac and SMA had true and false lumen perfusion, the right kidney was perfused through the false lumen, the left through the true. Both legs received true lumen flow.

Figure Centerline true lumen compression

The dissection started at the left subclavian artery origin. The false lumen compressed the true lumen up at the proximal descending thoracic aorta. This is an important finding because in this configuration with much of the filling of the dissection from the distal reentry sites, the false lumen acts like a pressurized, compressive lesion. With time, the adventitia around the false lumen may become aneurysmal if the false lumen fails to thrombose or obliterate. When the dissection is acute, the flap may cause a direct obstruction to flow or a dynamic one that depends on the pressure difference between true and false lumen.

Figure SMA thrombus with dissection

In this patient, thrombosis occured in the SMA beyond the origin due to dissection and decreased flow. This was consistent with the patient’s complaint of generalized abdominal pain and examination findings of pain out of proportion to the exam, indicating acute mesenteric ischemia.

His laboratory findings were within normal ranges, indicating this was early in the process. It is important to remember that no lab value correlates with acute mesenteric ischemia except very late in the process, and acute mesenteric ischemia remains a clinical diagnosis (reference 1) that is associated with a high mortality rate.

He was taken to the hybrid operating room. Right groin access was achieved and wire access to the arch was achieved. IVUS (Intravascular ultrasound, Volcano) was used to confirm the location of the wire -I believe this is an important adjunct as simply passing the wire doesn’t guarantee travel up the true lumen.

IVUS confirming true lumen access, and dissection flap compressing SMA origin
IVUS confirming true lumen access, and dissection flap compressing SMA origin
A conformable TAG endograft (CTAG, Gore) was delivered through a 24F sheath into position. Two devices were used to cover the thoracic aorta from the left subclavian artery to a position immediately above the celiac axis. The left subclavian was partially covered -the bare stents covering the rest.

Before deploying CTAG

Partial coverage of the left subclavian artery confirmed by persistence of strong left brachial artery pulse
Partial coverage of the left subclavian artery confirmed by persistence of strong left brachial artery pulse

Post Deployment of two 40mmx20cm CTAG (Gore) endografts
Post Deployment of two 40mmx20cm CTAG (Gore) endografts
This excluded the proximal entry tear of the TBAD. IVUS (image below) showed improved lumenal diameter of the true lumen into the SMA.

After stent graft placement in the thoracic aorta, the true lumen into the SMA expands
After stent graft placement in the thoracic aorta, the true lumen into the SMA expands
Once this was done, wire access into the SMA was achieved. This was technically challenging from the groin, and the backup plan was access from the left brachial artery which had been prepped. With patience, 6French access into the SMA was achieved. The origin was stented with a balloon expandable 8mm x3cm stent -sizing was based on IVUS and CT. This creates an alarming arteriogram as the stent appears oversized on subsequent runs -it is important to remember that the false lumen still takes up space beyond. Arteriography located the thrombosed segment and the reconstituted SMA beyond.

SMA beyond occlusion

Wire access was achieved across the thrombus. At this point, I had a range of options for thrombectomy including simply aspirating which retracting a catheter. This was not optimal as I could lose subsequent wire access or reenter the false lumen. The other option was an open thrombectomy and patch angioplasty -the thighs were prepped in case we had to harvest vein. Again, in the setting of dissection and going into the mesentery, an open revascularization while feasible, is challenging.

Thrombectomy catheters like Angiojet were available, but I chose to try the Export aspiration catheter (Medtronic). It is simple to set up and goes over a 0.14 wire. It is designed for the coronaries which have a similar lumenal diameter as the SMA. It worked well in this setting in retrieving thrombus which had a pale element that may have indicated some chronicity.

IMG_6111

The completion arteriogram was satisfying.

Post thrombectomy SMA

The SMA completely filled as did the celiac axis and both renal arteries. I opted not to treat the right renal artery as we had given 250mL of contrast, and it was filling well without intervention. The patient was making excellent urine and his blood pressure had been maintained with mean arterial pressures above 70mmHg. At this point, IVUS confirmed good deployment of the stent.

IVUS after SMA stent

The sheath was removed and the access site repaired. The general surgeons explored the patient and found all the bowel to be well perfused with pulsatile flows seen in the mesenteric arcade. The appendix was removed.

On waking, the patient was noted to not move his legs. A spinal drain was expertly placed by our cardiac anesthesia staff and his blood pressure was raised to MAP’s above 80. He recovered motor function in his legs soon after. I usually don’t place preop CSF drains in this scenario in the presence of good pelvic circulation, no history of infrarenal aortic interventions, and patency of the left subclavian artery. That said, with TEVAR of TBAD, there is a small incidence of paraplegia (1-5%) which I emphasize in my preoperative discussion.

He was started on heparin anticoagulation postop because of his history of SMV and now SMA thrombosis, interrupting it briefly to remove the CSF drain. A CTA was obtained to confirm absence of bleeding showing obliteration of the dissection in the aorta and good patency through the true lumen of the SMA.

CT before and after

pre and pos t SMA

Most importantly, he had complete relief of his abdominal pain.

The treatment of acute mesenteric ischemia has greatly evolved since I presented my paper in 2002. While open revascularization remains a gold standard, it is becoming increasingly apparent that good to better results may be obtained with an endovascular approach. Dan Clair, our chair, has made the comment that early revascularization with endovascular technique is analogous to emergent PTCA in occlusions of the coronary system and that re-establishing flow is a critical first step.

Open exploration still is the mainstay of managing acute mesenteric ischemia, but laparoscopic exploration remains feasible. This patient underwent open conversion after an initial laparoscopic exploration to remove a ruptured retrocecal appendix that had been treated for over a month on antibiotics. Without bowel necrosis, a second look is usually unnecessary, but is critical when threatened bowel is left behind.

Reference

  1. Park WM et al. J Vasc Surg. 2002 Mar;35(3):445-52.