ruptured thoracoabdominal aortic aneurysm

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.

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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.

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:

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.

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.

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.
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.
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.

The patient, an active 88 year old man, was transferred from an outside institution after a CT scan revealed a 9cm thoracoabdominal aortic aneurysm on workup of sudden onset back pain. On transfer, his blood pressure was stable but low in the 90’s. On arrival, his blood pressure dropped into the 60’s but responded to resuscitation, and after a detailed conversation with him about the risks of emergent repair, we brought him to the operating room.

The CT scan showed an 8.3cm extant III thoracabdominal aortic aneurysm which originated slightly above the diaphgragmatic hiatus and extended to the aortic bifurcation in two lobes. The larger lobe involved the visceral vessels and the infrarenal component was about 5cm.

While there was no frank rupture on the CT, the outside report mentioned haziness of the posterior wall consistent with ongoing rupture. Examination was significant for hypotension, abdominal and back pain, and a large pulsatile mass in the abdomen.

Despite the lack of contrast on this study, I was able to get a centerline reconstruction. The 3D virtual reality view then allows me to plan the operation virtually. The red and blue lines above bracket the beginning and end of the aortic aneurysm with the patient in a right lateral decubitus projection. A thoracoabdominal incision starting on the 8th rib was planned.

The patient remained stable through the intubation with a dual lumen endotracheal tube. The chest was entered and the left lung collapsed and the thoracic aorta in the chest was controlled for clamping. The retroperitoneum was dissected and the abdominal contents allowed to fall away exposing the remainder of the aneurysm. The diaphragm was taken down circumferentially. The aneurysm was leaking -not frankly but there was blood visible on the surface like a bruised, overripe plum of unusually large size.

The aorta was clamped in the chest after giving the patient 5000 units of heparin -I often don’t if there is a lot of blood loss and I anticipate factor depletion. The transdiaphragmatic aorta was controlled and the celiac axis (CA), superior mesenteric artery (SMA), and left renal artery were controlled with vessel loops. The aortic bifurcation was controlled as well after I considered anastomosing to the narrow segment of aorta around the renal arteries. While saving the infrarenal aneurysm for later has an appeal, I feel that if you cut the graft and start sewing to the aorta and find that it is not of good quality, you have wasted time. The aortic clamp was moved down from the chest to the transdiagphragmatic aorta which was now mobilized. This avoided for me some spinal cord ischemia but can be a risky move because the aorta was not healthy even in the nonaneurysmal segments. A 32mm Dacron graft what had 4 branches was brought into the field and anastomosed proximally with 4-0 polypropylene suture.

I picked up using narrow gauge suture for aortic anastomoses from my cardiothoracic surgery confreres at the Clinic (Eric Roselli, MD). They will use 5-0 polypropylene with the idea that the smaller needles result in smaller needle holes. I used to use 2-0 suture with an MH needle and have seen my partners be successful at it, often buttressing the anastomosis with a gusset (Dan Clair), but this patient had the tensile strength to take suture well so I went with the smaller SH needle and smaller gauge suture. Other maneuvers include sewing to a strip of Teflon, or in the case of terrible aortic tissues, using interrupted sutures which give some added stability but at the cost of time (credit to Tom Bower).

Time is the killer. While cell salvage gives you some margin for blood loss, this is lost with coagulopathy and hypothermia. The grafts to the viscera were sent from distal to proximal -I feel this greatly eases wire access if needed from a femoral access. There can be a problem with twisting, and I avoid this two ways -by allowing for generous length with looping around the main graft to create forgiveness -closing the retroperitoneum inevitably twists the graft -this I credit to my former partner Pat O’Hara who retired last year. The right renal artery received the first graft while cold saline was given to the left renal artery which was revascularized last. Neither had ostial lesions which I have learned to stent with a bare metal stent directly with the artery open -this I credit to Jeanwan Kang, MD, one of my current partners. The CA graft resulted in great back bleeding from the SMA. The SMA graft and left renal artery grafts completed the visceral segment of the case.

The distal anastomosis was challenging because the bifurcation was heavily calcified. I have to say, the distal often will give me fits when the proximal does not because of the calcium. I generally do perform an endarectomy, but this often results in very poor remnant adventitia. The advice here is be prepared to go distally, but consider that it may add time to the case.

The hemostasis was obtained -the most important factor in hemostasis is early and successful repercussion. The wound was restored with repair of the diaphragm, closure of the chest over two chest tubes and closure of the abdomen.

The success of these patients only begins with the operation which I cannot do without the active participation of our cardiac anesthesia, nursing, and trainees -our fellow Eric Shang did his work competently. I am fortunate to have strong help in our vascular intensive care unit. There, my patient was actively resuscitated with blood product, stabilized, and weaned off the ventilator within 2 days. Fortunately, he was not paralyzed by this operation which can happen in up to 10% of patient. Also, his renal function stabilized and he never required dialysis. He was eventually discharged to rehab in under 2 weeks. He returned to my office about a month after the rupture, walked in, accompanied by his family. He was making progress with his rehab, and his wounds had healed well.

Various indices are formulated to predict outcome, which traditionally are viewed as poor for open repair on octogenarians. I am still old fashioned and rely on the “eyeball” test. Several risk stratifying schemes have been published. Most recently, the group from Harborview (link, another link) published a simple stratification scheme for infrarenal AAA rupture. Garland et al (in press) found that having combinations of the following factors predicted mortality well for ruptured AAA including:

Age >76
preop Cr>2.0mg/dL
BP<70mmHg at any point
arterial pH<7.2

Mortality risk based on number 1-4 of positive risk predictors — Mortality risk

If this was a ruptured infrarenal AAA, the patient had two of the risk factors -age>76 and BP<70mmHg, which conferred a risk of 80% mortality for open repair, which translates to a higher number for thoracoabdominal aortic aneurysm repair.

One of our recent aortic fellows, Muhammad Aftab, published the Baylor experience on open repair of TAAA when he was there and found that for open repair, rupture conferred an independent risk for death with a OR of 5.7.

Despite the dismal statistics, several intangibles did favor survival in the patient. He was at 88 still a working professional. He exercised everyday and was fit. He did not drink to excess and never smoked. And he had complete understanding during our preoperative conversation and had a strong grip. And he survived waiting several hours at his hospital for workup and eventual transfer which is a stress test. This last factor accounts for the higher mortality rates for rupture that occurs in hospitals and in places like Seattle where the EMS transport is highly efficient, and better mortality rates at rural referral centers like Mayo where the filtering effect of time leaves a greater proportion of patients likely to survive an operation for rupture.

Reference

Aftab et al. J Thorac Cardiovasc Surg 2015;149:S34-S41

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