PAD

The shunt as temporary bypass -a modest proposal

Posted on August 3, 2019August 4, 2019 by docpark

The rise of cardiopulmonary bypass life support has also given a rise to the need to keep large, obstructive cannulas in femoral arteries. ECMO cannulas are often kept in for days, and it is not uncommon to discover limb ischemia and infarction relatively late. This can be avoided by placing a distal perfusion cannula to shunt blood to the leg early in the ECMO process. The ECMO cannulas have a convenient side port to send a little flow to a 6F sheath placed in the femoral or popliteal artery. This is an established technique (reference 1, sketch below), and it works despite the modest flows achieved because it does not take much to keep the leg alive. These patients are not walking, nor are they need to heal leg wounds, so just enough blood flow means something just a little more than what they get when the common femoral artery is completely occluded by the life support cannulas. What is fascinating to me is that these shunts can pptentially help to save limbs when used as temporary extracorporeal bypasses when definitive vascular surgical care is not immediately available.

brachial to femoral shunt sketch

When I was a medical student, I took on a research project after my first year where I had a Langendorff preparation of a rat heart (below).

langendorff prep in MRI — an isolated, perfused, beating rat heart placed in a superconducting magnet for NMR spectra acquisition

My project was to take a rat heart and keep it alive, beating, and even working, through a perfusion apparatus and place this inside a superconductive magnet to obtain Phosphorus nuclear magnetic resonance spectra -intracellular metabolism data including concentration of ATP, intracellular pH, and ATP/ADP ratio. While the project was successful -I am quite proud to have been the only person at Columbia to have successfully acquired NMR-S data with living beating heart, I moved on to other interests and took away this concept: with oxygenated, glucose enriched, isoosmolar fluid perfused at arterial pressure, any organ can be kept alive, possibly indefinitely, including a brain which only recently others have found possible (reference 2) in reputable scientific circles, but the the Nature publishing Yalies were scooped by the Simpsons decades ago (below), and maybe Mary Shelley centuries before,

simpsons head

This is the simple idea. Revascularization is keeping the target vascular bed alive by delivering oxygenated blood. With a shunt, it could be little, it could be a lot, but it certainly is better than zero, and even a little can buy you time.

The breakthrough that I had was several years ago, a patient arrived from another hospital with an Impella pump which did not have a side port like an ECMO cannula. It is a large catheter that augments cardiac output and in the patient that I was asked to see this patient as their leg was cold and pulseless. Their cardiac output was very poor, and they were sustaining an augmented systolic pressure in the 90’s. There was no way to get this patient to the operating room for a revascularization of any sort. It did strike me that the patient had the misfortune of having catastrophic heart failure in the absence of significant athersclerosis and had normal brachial arteries. After discussing the ramifications with the ICU and family, I placed a brachial artery 5F cannula, and connected it to a 5F sheath I placed in the superficial femoral artery below the occlusive common femoral sheath (figure below). A doppler on the tubing connecting the two cannulas confirmed flow and the patient’s left hand maintained a pulsatile oximetry waveform. The leg pinked up and eventually there was a signal in the foot. This managed to perfuse the leg which did better than the patient who succumbed to multiorgan failure from heart failure. The leg did great.

Which leads me to these thoughts. Most hospitals are good at diagnosing large vessel occlusion via CTA. Most hospitals have doctors who can place arterial lines with ultrasound guidance. In the instance of aortoiliac occlusion or femoral occlusion from thromboemboliem, time is a critical limiting factor to limb salvage. Many hospitals do not have vascular surgeons. Many hospitals transfer these patients with a heparin drip but in the ischemic condition. Transfer arrangements may take hours. Why not ameliorate this situation by having an appropriate physician -an anesthesiologist, an intensivist, an EM physician, place an ultrasound guided radial or brachial arterial line, connect to arterial line tubing to a dorsalis pedis arterial line. Tape it all down on the patient after confirming flow (crude sketch below). This would be better than the three extra hours of ischemia the patient gets hit with on transfer. No one would transport a donor kidney without adequate perfusion and protection, but dying legs get transferred all the time with established warm ischemia. If done well, it might turn an emergency procedure into an urgent, semi-elective one. Have the vascular surgeon video conference in to confirm the absence of blood flow and appropriateness of temporary shunting.

radial to dp shunt — radial artery to dorsalis pedis artery shunt

If we are to live in a world with less vascular surgeons, then the radius of survival has to be extended with use of technology and simple ideas such as this. Comments are welcome.

Reference
1. Foltan M, Philipp A, Göbölös L, Holzamer A,
Schneckenpointner R, Lehle K, Kornilov I, Schmid C, Lunz D. Quantitative assessment of peripheral limb perfusion using a modified distal arterial cannula in venoarterial ECMO settings. Perfusion. 2019 Mar 13:267659118816934. doi: 10.1177/0267659118816934.

2. Vrselja, Z., Daniele, S. G., Silbereis, J., Talpo, F., Morozov, Y. M., Sousa, A. M. Mario, S., Mihovil, P., Navjot, K., Zhuan, Z. W., Liu, Z., Alkawadri, R., Sinusas, A. J., Latham, S.R., Waxman, S. G., & Sestan, N. (2019). Restoration of brain circulation and cellular functions hours post-mortem. Nature, 568(7752), 336–343.

Never say never

Posted on July 30, 2019 by docpark

If you work long enough, you will not only see everything, but you may end up doing something that you say you would never do. You will be confronted with a scenario that would test not just your skills but also your boundaries. The adage, never say never is a warning that all of us may face a choice -to remain rigidly consistent with some earlier proclamation or to excuse a little hypocrisy for the sake of the patient.

At one point in recent years, I saw a patient who had an axillary artery to anterior tibial artery bypass with PTFE (figure above). That was a kind of marvel to me, but my initial response was a bit of a sneer.

“Who does this?” I thought.

Giving it some thought, the rationale could have been to spare the patient from a hip disarticulation as the patient had had failed revascularizations and was occluded from the infrarenal aorta to the anterior tibial artery on that side. If you see such a thing, it sparks wonder as it feels both wrong and splendid at the same time because some surgeon had the audacity to pull it off. By the time I saw it, the patient had avulsed the proximal anastomosis, infarcted their leg to their thigh, and was headed for a hip disarticulation, four years after the creation of the bypass. Four years of patency!

It was no wonder I remembered this case when this middle aged man presented to our clinic with a gangrenous right third toe. He had diabetes, hypertension, CAD with prior PTCA, prior acute mesenteric ischemia with bowel resection with an SMA stent, CHF with moderately reduced EF, CKD, and aortoiliac occlusive disease treated in past with aorto-bi-iliac bypass, left to right fem-fem bypass complicated by graft infection requiring resection of the fem-fem bypass, with subsequent development of rest pain on left leg and gangrene on right leg. He had been told at his home institution that he required eventual bilateral hip disarticulations. At the time of consultation, he was minimally ambulatory, limited by severe pain. He had been this way for over a year.

On examination, he had heavy scarring in both groins from prior open incisions healed by secondary intention, a midline laparotomy incision. He had weak bilateral axillary and brachial artery pulses. He had no pulses in either leg. The right foot had gangrene of the distal phalanx of the third toe. The both feet were anemic and painful -the left foot had more dependent rubor. Pulse volume recordings were flat in both legs. TCPO2 was in the 20-40mmHg range at the thighs bilaterally suggesting reduced potential for healing an above knee amputation. Vein mapping showed no suitable saphenous vein in either leg. CTA (figure below) showed both external iliac arteries to be occluded or absent and the common femoral arteries to be occluded or missing bilaterally.

AngioRunOff 1.0 B20f

The left femoral bifurcation was preserved and the left SFA was patent into small underfilled tibial vessels. On the right, there was an isolated segment of profunda femoral artery that reconstituted from pelvic collaterals. The right below knee popliteal artery reconstituted and had underfilled but patent three vessel runoff (figure below).

The patient was admitted for workup and treatment. Heparin drip was started. In the setting of rest pain, I find that heparin drip improves circulation and symptoms even though it shouldn’t. I don’t have a great explanation for this, but it does, and I would welcome comments. To better assess how much operation the patient could tolerate, a cardiac risk assessment was performed. He was deemed a moderate to severely elevated risk due to his EF of 35% but had a normal nuclear stress test.

The options I presented to the patient were
1. Hip disarticulations
2. Bilateral above knee amputations with a wait and see approach to hip disrticulation
3. Sympathectomy
4. Axillo-profunda or popliteal bypass on right and Axillo femoral bypass on left
5. Ilio-right popliteal and left femoral bypass.
6. Thoracic or supraceliac aorta to right profunda and left femoral bypass

Hip disarticulation is the bogeyman of leg amputations done for peripheral vascular disease. When done for trauma or cancer in young people, the ability to rehab and walk again is excellent. When done for tissue loss in elderly, non-ambulatory patients, the reported mortality of the operation rises to above 50%. It is usually posed as a lead in to comfort measures. The above knee amputations were not likely to heal despite the neither here nor there findings of the TCPO2 which is only good when the results or normal or dismally low. Sympathectomy is an option for those without options, but this patient still had options, I felt.

Any revascularization relies on the choice of inflow, outlow, and conduit. In endovascular revascularizations, the conduit is the previously occluded vessels, but in this instance, because of the infected grafts, there was neither continuity, nor a good option even if there was as the common femoral artery is a terrible recipient of endovascular therapy. The options then devolve to choosing an inflow. The axillary arteries are technically easiest to access and manage and form the basis of treatment of high risk patients requiring limb salvage who have no endovascular options. The axillofemoral bypass is given a bad reputation of having a poor patency, but the key is the quality of the vessels and the number of potential tension, compression, and kink points. I think the reason why the axillary to anterior tibial bypass lasted for four years in the first patient had to do with his immobility, and the pristine nature of the anterior tibial artery -the only patent vessel below his umbilicus. Here to, the inflow disease appears to have spared his right popliteal artery and his left superficial femoral artery.

The only compromise with an axillary artery inflow is the amount of potential flow. In a patient with a 6-7mm axillary artery, the amount of flow going to both an arm and a leg, and a lower torso, would greatly exceed the flow capacity of that vessel. The infrarenal aorta on this man is graft and is relatively inaccessible due to the prior laparotomy for acute mesenteric ischemia, signalling the high likelihood of adhesions. The supraceliac aorta is an excellent inflow source and I have had good results dissecting it out laparoscopically as it is often deep and narrow an exposure to try to dissect open -While the retroperitoneal tunneling can be tricky, it is not insurmountable and good bypasses can result (link).

My eye focused on the left iliac graft which perfused the internal iliac artery on that side. The graft was generous, and likely a dilated 8mm graft, and could be exposed via a left lower quadrant retroperitoneal exposure (the transplant exposure). This would allow me to to then tunnel to avoid the terribly scarred groins. On the right side, the obdurator canal could be traversed into the postioer compartment of the thigh -a graft could be sent to the below knee popliteal artery with a side graft to the tiny profunda femoral artery. On the left, the graft could be tunneled laterally near the insertion of the sartorius muscle and onto the superficial femoral artery. All of the incisions would be made in virgin skin, the only redo dissection being digging out the left iliac graft while avoiding injury to the ureter.

So I proposed a ilio-popliteal bypass. Not quite an axillo-tibial bypass, but almost there. There was some karmic balance being restored by my taking decision. It would be with PTFE all around. I quoted a 5-15% risk of major morbidity and mortality, lifelong anticoagulation, and right third toe amputation. The patient agreed.

Sketch001 — sketch of iliopopliteal and iliofemoral bypassrs

The operation was done in a hybrid suite, as should all limb salvage cases. The retroperitoneal dissection was challenging because of the heavy scar tissue around the well incorporated iliac bypass, but with patience, a clampable 3cm segment was achieved. I am a big fan of Wylie hypogastric clamps because they stay out of the way when placed in a tight narrow spot, and for that same reason, I prefer the Cherry supraceliac aortic clamp. They were designed by my mentor, Ken Cherry, and his mentor, Jack Wylie for this kind of operation. A few venous bleeders were easily handled with my ring compressors (below), and I hope to continue this chain of innovation, but I digress.

The bladder was dissected off the pubis to allow the graft to be tunneled to the right pelvis. A counter incision in the right lower quadrant abdomen and a mid thigh incision mobilizins the anterior compartment muscles to the posterior compartment allowed me to tunnel across the obturator foramen. The obdurator vessels need to be avoided or there will be bleeding. this mid thigh incision allowed exposure of the profunda femoral artery more proximally and allowe the graft to be tunneled anatomically to the below knee popliteal artery for anastomosis. A jump graft was taken off this graft on the thigh to the profunda femoral artery which was small and diseased -no more than 2mm in size. An axillary bypass to this profunda would be doomed to the compromised patency rate published for ax-fem bypasses giving them a bad name. The left superficial femoral artery was exposed and provided outflow to the left iliofemoral bypass which was tunneled far laterally under the inguinal ligament to avoid the scar tissue where the common femoral artery was.

There was immediately multiphasic signal in both feet on release of clamps. After closure of all the incisions and dressings, the right middle toe was amputated.

The patient recently came back for an 8 month followup. His grafts remained patent and he was walking without limitations. Given the high quality of the inflow (large iliac graft), and the amount of decent outflow -the right popliteal and profunda, the left superficial femoral and retrograde to the profunda, gives the patients some surety of longevity for his grafts. These grafts will need lifelong surveillance.

I have since opened my mind a bit about that axillary artery to anterior tibial artery bypass. When given the choice between comfort measures for an otherwise nonambulatory but alert patient and hip disarticulation with its attendant high risk, a bypass from a large axillary artery to a large, relatively disease free anterior tibial artery is not the worst thing that could happen. For that patient, it gave them 4 more years with their family, which in any measure, is priceless. To that patient’s family, that surgeon was a savior.

Zebras, not horses: popliteal artery entrapment syndrome

Posted on July 17, 2019July 17, 2019 by docpark

mega mushroom — Adding a vascular surgeon to a hospital is like eating one of these. It turns Mario into Mega Mario. Vascular surgeons turn community hospitals into tertiary care centers.

Recalling the medical school adage, “when you hear hoofbeats, it’s probably horses, not zebras,” it is critical to think about rarities down on the differential list whenever you come across a patient. Vascular diseases suffer from inadvertent obscurantism arising from its absence from medical school curricula such that common disorders like mesenteric ischemia and critical limb threatening ischemia are frequently missed by even experienced medical practitioners. Vascular zebras are even harder to pin down because many experienced vascular specialists practice for years before they encounter, for example, adventitial cystic disease or dysphagia lusoria with a Kommerell’s diverticulum. Even so, real patients have these disorders, and we are all subject to inexperience bias -the feeling that something does not exist until you see it. You may completely miss something staring at you in the face or worse, deny its existence.

The patient is a middle aged man in his 50’s who aside from mild hypertension had no real risk factors. One day, at work, his right leg stopped working. He developed a severe calf cramp and the forefoot was numb and cool. He went to his local hospital and the doctors there appreciated the lack of pulses in the right leg and got a CTA, of which I only had the report which found a right popliteal artery occlusion.

The next morning, as he had signals and was not having rest pain, his doctors discharged the patient on clopidogrel and scheduled for angiography and stenting, per patient. As his debilitating claudication did not go away over the weekend, he came to our emergency room. While he had no rest pain, he did have minimal walking distance before his calf muscles seized up. On exam, his right foot was cool and cyanotic, with intact motor function and sensation. There was a weak monophasic posterior tibial artery signal. Bedside point of care photoplethysmography showed dampened waveforms (below).

Look at the blue line. The waveforms are dampened in the ischemic foot.

Because he did not bring his CT, I repeated the study. I have written extensively on the need to be able to share CTA studies without barriers. After his study, I brought it up on 3D reconstruction software.

It clearly showed a Type II Popliteal Artery Entrapment affecting both legs (CTA images in series above). Stenting it would have failed. I spoke with the patient about operating the next day. The plan was popliteal artery exploration and thromboendartectomy with myotomy of the congenitally errant medial head of the gastrocnemius muscle. The patient was agreeable and I took him to the operating room for a myotomy and popliteal thrombendarterectomy in the prone position. The medial head of the gastrocnemius muscle went over the popliteal artery and inserted laterally onto the femur.

pop opened.png — Endofibrosis, cut medial head of gastrocnemius muscle to right of distal clsmp

The artery was opened and while there was fresh clot, the artery showed signs of chronic injury as evidence by endofibrosis which pealed off. Pathology showed to be fibrotic in nature.

04-SP-19-4119 Trichorme stain showing fibrous tissue as green — Trichrome stain showing chronic endofibrosis

The artery was repaired with a pericardial patch and flow restored to the tibials, not all of which were completely patent.

pop patched.png

The patient was discharged after about a week and will be scheduling repair of his contralateral popliteal artery entrapment.

The vascular surgeon has a vital role in a hospital’s medical ecosystem. One time, I heard hospital administrator say that with the advance of endovascular technologies, the vascular surgeon would become an expensive, redundant luxury easily replaced by the overlapping skillset of radiologists, cardiologists, general surgeons, trauma surgeons, cardiac surgeons, nephrologists, neurosurgeons, neurologists, podiatrists, infectious disease, and wound care specialists. When I identify these zebras, these rare diagnoses, I am neither replacing all those aforementioned specialties, nor having special insight unavailable to the uninitiated. I am keeping my eyes open. In a non-smoking, active, otherwise healthy and employed middle aged man with no cardiac history, it is very strange to have isolated popliteal occlusion with otherwise pristine arteries throughout the rest of the CT scan. That is a statistical outlier. People who occlude blood vessels in this fashion usually have more comorbidities, usually are older, and usually have more atherosclerotic disease burden. While not quite like the teenager who presented last year with the same diagnosis (after a month of misdiagnosis and delayed treatment), the cleanliness of the arteries elsewhere in the body was disturbing to me. This puts me on a zebra hunt and not the usual horse roundup.

A hospital needs vascular surgeons in the way that America need the US Marine Corps. Every decade, there is some congressional movement to see how the USMC, which has fighter jets, tanks, planes, aircraft carriers, helicopters, and riflemen, can be phased out because it seems to duplicate the services of the Navy, Air Force, and Army, and every generation a conflict proves these arguments wrong. Individuals who know things broadly and deeply, who can do many things across specialty lines, work from head to toe, and whose specialty is to customize solutions to complex problems is the special quality that is the difference between tertiary hospitals and quaternary hospitals. While these qualities are goals within Vascular Surgery, it is a generalizable goal for anyone working in healthcare. My favorite professor in medical school was Dr. Harold Neu, chair of infectious diseases at P&S. He knew everything and was interested in everything and took every moment in the hospital to increase his knowledge a little more. That’s how and why I diagnosed a case of schistosomiasis earlier this year -the upper abdominal pain was not from a coincidental aortic aneurysm, but the fellow did swim in the Nile.

I texted Dr. Sean Lyden, my former boss and partner at the Cleveland Clinic main campus, if there was any situation where an asymptomatic popliteal entrapment who had gone over 50 years of life without complications could just be watched -it was a question from the patient actually. Dr. Lyden treats popliteal entrapment weekly and maintains a clinic specializing in popliteal artery entrapment (link). One of advantages of working in vascular is that the community is small and highly accessible, and I have a group of living textbooks on speed dial (that term pegs me as antique). There is an active social network of vascular specialists and the SVS maintains SVS Connect (link) for posting and discussing difficult questions. Despite the horrible hour that he received the text (“What’s the matter? Are you in trouble?” he asked) because of the time differences between Abu Dhabi and Cleveland, he answered, “no.” Sorry, Sean, for texting you at 4 in the morning.

When you look for four leaf clovers, and you have never seen one in your life, the moment you find one must be transformative. I have never found one, but I keep my eyes open, lest I trod on one.

Arterial Restoration -Something New, Something Old

Posted on September 13, 2017 by docpark

Something that I recently promised Dr. James S.T. Yao, I will be working to publish on my stent removal and extended remote endarterectomy cases and techniques. Meanwhile, here is a talk.

Bypasses still work -a guest post from Dr. Max Wohlauer

Posted on December 7, 2016December 9, 2016 by docpark

pre-angio

angio text.png

Max Wohlauer, a recent graduate, is now Assistant Professor of Surgery at the Medical College of Wisconsin in the Division of Vascular Surgery. He sent along a case which is published with his patient’s and department’s permission.

The patient is an 80 year old man with diabetes mellitus, CHF, and pulmonary fibrosis, who presents with right foot toe ulcers. He had an inflow procedure earlier in the year, but it failed to heal the ulcers. An attempt at crossing a CTO of the SFA/POP failed. Angiogram (above), showed a distal anterior tibial artery target.

Preop ABI, TBI’s, toe waveforms, and pulse Dopplers are shown. are as shown.

preop TBI.png preop-abi

All point to likely limb loss. The TBI is 0 and the ABI is incompressible. Max planned for bypass. The saphenous vein was mapped and shown to be adequate.

preop saph vein mapping.png

Max comments:

Compromised runoff on angio. Cutdown on AT and determined it was adequate target at start of case
Right fem-AT bypass
Re-do groin exposure
Translocated non-reversed GSV
Subcutaneous tunnel

The operation went well. Completion angiography was performed showing a patent bypass and distal anastomosis with good runoff.

completion angiography.png

A followup duplex showed patency of the graft.

postop duplex.png

Postop ABI’s showed excellent results:

Postop TBI.png

Commentary from Park

Bypasses work and are possible even in high risk individuals with good anesthesia and postoperative care. Because open vascular surgical skills are not well distributed while endovascular skills are more widely distributed, there is bias both in the popular mind and even among some catheter based specialists that bypass surgery is a terrible, no good thing. The fact is that a well planned bypass is usually both effective and durable even in high risk patients, but clearly it is not the only option.

Ongoing developments in endovascular technology bring greater possibilities for revasularizing patients. As someone who does both interventions and operations, I have seen spectacular success (and occasional failure) with both approaches, and I admit to having biases. It is human nature to be biased, but it is because of my biases, I support further ongoing study, as the mistake would be to establish monumental truths without supporting evidence. There is an ongoing randomized prospective trial (BEST-CLI) that aims to answer important questions about what approach brings about the best results in critical limb ischemia. It will bring evidence and hopefully, clarity, to this important disease.*

Finally, I am very proud to have participated in Dr. Wohlauer’s training, and look forward to seeing his evidence, experience, and even biases, presented at future meetings.

*CCF is a BEST-CLI study site.

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

Posted on September 27, 2016September 27, 2016 by docpark

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.

The femoral bifurcation does not tolerate endovascular miscalculation

Posted on December 18, 2015 by docpark

Sketch185115048

The patient presented with complaints of leg and foot pain with sitting and short distance calf claudication, being unable to walk more than 100 feet. This is unusual because sitting usually relieves ischemic rest pain. He is in late middle age and developed claudication a year prior to presentation that was treated with stent grafting of his superficial femoral artery from its origin to Hunter’s canal at his local hospital. This relieved his claudication only briefly, but when the pain recurred a few months after treatment, it was far worse than what he had originally. Now, when he sat at his desk, his foot would go numb very quickly and he would have to lie down to relieve his pain.

On examination, the patient was moderately obese with overhanging belly. He had a palpable right femoral pulse, but nothing below was palpable. He had multiphasic signals in the dorsalis pedis and posterior tibial arteries. The left leg had a normal arterial exam. Pulse volume recording and segmental pressures were measured:

preop PVR2

These are taken with the patient lying down which was the position that relieved his pain, and the PVR’s show some diminishment of inflow. It would be easy at this point to declare the patient’s pain to be due to neuropathy or spinal stenosis, but because of his inability to walk more than a hundred feet and because of his severe pain with sitting, I went ahead and obtained a CTA.

3DVR

The CTA showed he had an occluded superficial femoral artery (SFA) with patent profunda femoral artery (PFA) with reconstitution of an above knee popliteal artery with multivessel runoff. The 3DVR image showed his inguinal crease to be right over the femoral bifurcation which is not an unsual finding, but his stent graft was partially occluding his profunda femoral artery.

CTA centerline

I decided to take him to the operating room to relieve his PFA of this obstruction. My plan was to remove the stent graft at the origin of the SFA and at the same time, remove the plaque and occluded stent graft from his SFA to restore it to patency.

In the OR, on exposing his SFA, I discovered that because of his overhanging belly, his inguinal ligament had sagged and was compressing his femoral bifurcation.

Sketch185115048

This explained his presentation. The stent graft really had no chance as when he sat, the belly and ligament compressed it at the origin, and because it partially occluded the origin of the PFA, sitting probably pinched off flow completely. The 3dVR image shows the mid segment of PFA to have little contrast density -this is not because of thrombus, but because of the obstruction, the PFA was getting collateral flow from the hypogastric artery.

The stent graft was removed at its origin via a longitudinal arteriotomy after remote endarterectomy of the distal graft.

In this case, the Multitool (LeMaitre) was useful in dissecting the plaque and stent graft because of its relatively stiff shaft compared to the standard Vollmer rings. The technique of EndoRE has been described in prior posts (link).

procedure picture

The stent graft came out in a single segment -they come out easier than bare stents.

post angio composite The patient regained palpable pulses in his right foot and recovered well, being discharged home after a 4 day stay.

While one could argue that just taking out the short piece of occlusive stent graft over the PFA was all that was necessary, I feel that there is no added harm in sending down a dissector around the stent, and in this patient there was restoration of his SFA patency which was the intent of the original procedure.

Unlike PTFE bypasses that sometimes fail with thromboembolism, SFA EndoRE fails with development of focal stenoses. From a conversation I had with Dr. Frans Moll at the VEITH meeting, I found that he has had good experience with using drug coated balloons in the treatment of these recurrent stenoses.

At the time of discharge, the patient was relieved of his rest pain, and was no longer claudicating. The common femoral artery, its bifurcation, and the profunda femoral artery remain resistent to attempts at endovascular treatment, and remain in the domain of open surgery. And in retrospect, the history and physical examination had all the clues to the eventual answer to the oddities of the patient’s complaints. The combination of inguinal crease, abdominal pannus, and low hanging inguinal ligament meant these structures acted to crush the stent graft and femoral bifurcation.

The Ilio-femoral-popliteal remote endarterectomy -The Concept Behind Extended Remote Endarterectomy is Moving Inflow from the Groin to the Knee

Posted on October 28, 2015October 28, 2015 by docpark

Why perform such an extensive endarterectomy when just a few stents will do? This is a valid question, given the relative safety of interventions and the durability of bypasses. There are three reasons why ilio-femoral-popliteal endarterectomy works well in my practice.

Minimally invasive
Restore elasticity and collaterals
Move the inflow point from the groin to the knee

The procedure is minimally invasive. Take for example this patient whose plaque is shown above. He had a common femoral occlusion for which a common femoral endarterectomy was aborted when the prior surgeon ran into excessive bleeding. Workup for coagulopathy was negative and the patient came to me with rest pain. Pedal level pulses were not palpable, and the signals were barely there.

CTA showed that he had a CFA occlusion as well as SFA occlusion.

Because the common femoral plaque is contiguous with the external iliac plaque, it is often simpler to complete a remote endarterectomy over wire up to the external iliac origin than to try to get a satisfactory end point at the inguinal ligament -I do not like stenting across the ligament into the patch which is the usual bailout if the end point causes a stenosis. It is far simpler to apply a stent at the external iliac origin.

The popliteal end point was chosen where the visible plaque was no longer apparent in the patent artery. The goal is to cut across thin intima, and frequently no distal stent is required because a secure end point is achieved much like the “feathered endpoint” seen in carotid endarterectomies.

My intention was to endarterectomize the atherosclerotic plaque from the external iliac origin to popliteal artery via the groin incision marked in orange.

3DVR allows for planning the operation in great detail

The video shows the setup and motion in dissecting the plaque.

The plaque came out easily (first image, top).The proximal and distal end points required stents.

The patient regained palpable dorsalis pedis and posterior tibial artery pulses. Total OR time was less than 2 hours. An ilioinguinal field block allowed for good pain control and the patient was discharged the next morning, having to heal only a 10cm wound. There is no good endovascular option for common femoral disease, and while stenting the whole SFA can be done, on more than a few occasions I have had to treat occluded “full metal jacket” SFA stents, usually by removing them. EndoRE has been shown to be superior to PTFE and almost as good as vein in the REVAS Trial when compared to fem-AK POP bypass. Going home the next day after such an extensive revascularization is not a stunt -it’s the direct result of limiting the incision and blood loss and OR time.

2. Restore Elasticity and Collaterals -Arterial Restoration

One of the components of arterial flow that is lost with atherosclerotic disease is arterial elasticity. That is the stretchiness of the artery in response to pressure. Elastic distension and recoil account for significant portions of forward flow during diastole which is lost with atherosclerotic plaque. As plaque builds up, and the artery becomes stiffer. The artery that goes through remote endarterectomy regains this elasticity. Ultrastructure from a recanalized external iliac artery sampled from a punch arteriotomy for a cross ilio-femoral bypass showed that three months after endarterectomy, the external iliac artery was ultrastructurally normal per pathology report.

Also, collaterals that were previously occluded are seen to be restored to patency. This has an important impact on patency and any future failures. The endarterectomized arteries fail due to the presence of isolated, random fragments of medial smooth muscle which cause focal TASC A restenoses. These are easily amenable to balloon angioplasty. If the revascularization fails, there is no catastrophic thromboembolism that is typical of PTFE thromboses -rather the collaterals keep segments open and it is straightforward to thrombectomize or lyse the artery and intervene as necessary.

3. Moving the inflow point from groin to the knee.

This is an important concept. One of the principles of inflow restoration is delivering large flow and pressure directly from the aortic source to the leg. Recanalizing from the external iliac to the below knee popliteal artery creates this situation below the knee, allowing for very short bypasses to be performed from the popltieal artery to tibial targets -a very useful circumstance when vein is limited. This next patient is a presented with gangrene of his fifth toe after esophagectomy for cancer, and had severe diabetes.

He had useful saphenous vein in his thigh only, some of it having been harvested in the proximal thigh for a common femoral endarterectomy. CTA showed a dilated common femoral and profunda femoral artery, severely calcified SFA and popliteal artery which were occluded, and only a patent peroneal artery as runoff.

The plan was to harvest the short segment of vein then through the same incisions, below the knee and in the mid thigh, expose the below knee popliteal artery and tibial origins, and the mid SFA. I intended to avoid the groin. The plaque was removed from the tibioperoneal trunk to the SFA origin, and the origin was stented.

This reestablished a normal inflow at the level of the below knee popliteal artery. I also did an eversion endarterectomy of the anterior tibial artery which resulted in significant back bleeding -a good sign. A short bypass was performed from the below knee popliteal artery to the peroneal artery.

This resulted in a palpable dorsalis pedis artery pulse and excellent peroneal and posterior tibial artery signal.

The ABI improved and the waveforms predicted healing for his 5th ray amp.

This last case illustrates the point that once the conceptual inflow point is moved to the below knee popliteal artery, bypasses can become short, and durable tibial revascularizations become feasible. By avoiding a redo groin, avoiding multisegment arm vein bypass, and keeping the procedure time under 5 hours, the operation remains less invasive.

When Better is Better Than Good

Posted on October 13, 2015October 13, 2015 by docpark

The dictum that better is the enemy of good is one of the old chestnuts carried around surgery training forever. It is an admonition against an unhealthy perfectionism that arises from either vanity or self doubt, and in the worse cases, both. The typical scenario is a surgeon trying to make a textbook picture perfect result and finding the patient’s tissues lacking, will take down their work to make it better, and repeat this process while the patient and everyone else in the room lingers.

Trying to avoid this, many surgeons will try to avoid any difficulties -the bad patch of scar tissue, irradiated body parts, areas of prior infection. But the mental contortions involved in avoiding “perfect” can result in actual physical contortions that in the end don’t pay off in good enough. I have not been immune to this, and I don’t think any physician or surgeon can honestly say they haven’t experienced some variation on this.

This patient is a younger middle aged man who in his youth experienced a posterior dislocation of his left knee, resulting in an arterial transection. This was repaired with an in-situ graft. Subsequently, he had complications of osteomyelitis and had his knee fused after resection of his joint. He did well with this bypass for several decades, but it finally failed several years ago, and a new one was created (image above).

Rather than directing the graft in line as in the previous one, this was was taken from a medial exposure of the femoral artery and tunneled superficially around the fused knee to coil lateral, ending in the anterior tibial artery.

This graft in turn thrombosed and was lysed by the outside surgeons and underwent serial interventions of proximal and distal stenoses at the anastomoses. The patient, when I met him, was contemplating an above knee amputation as a path to returning to work as a nurse in a rural hospital.

While there should be no reason long bypasses should do any less better than short bypasses, I do have to say these things about this patient’s bypass:

No vein is perfect and the longer your bypass, the more chances you will have that a segment of bad vein will end up in your bypass
Turning flow sharply can cause harsh turbulence. Turbulence can cause transition of potential energy into kinetic energy which acts to damage intimal, resulting in intimal hyperplasia.
Thrombosis is a sure sign that your graft is disadvantaged, and the longer the period of thrombosis, the longer the intima “cooks” in the inflammatory response that accompanies thrombosis, making the vein graft even more vulnerable to subsequent intimal hyperplasia, thrombosis, or stricture.
A high flow, small diameter vein graft entering a larger, disease free bed results in more turbulence but also Bernoulli effects that cause the graft to close intermittently, vibrating like one of those party favors that make a Bronx Cheer (a Heimlich valve). This is the cause I think of the distal long segment narrowing on this graft.

This patient was decided on amputation when our service was consulted, and after reviewing his CTA, I offered balloon angioplasty as his symptoms were primarily of paresthesia and neuropathic pain. I used cutting balloons and got angiographically satisfactory results.

The patient, although he admitted to feeling much better, was sad. He relayed that he had felt this way several times before, only to have his life interrupted by pain and weakness signaling a restenosis.

A direct graft would require about 10 centimeters of vein

It was only a month later when I heard the patient had returned with the same symptoms. He wasn’t angry nor full of any “I told you so” that frankly I was muttering to myself. Reviewing his CTA, he had restenosed to a pinhole. The vein, to use a scientific term, was “no good.”

The other interesting finding was that he had an abundance of very good vein. Following surgical dictum, his original and subsequent surgeons had used his vein from his contralateral saphenous vein. His right leg, fused at the knee, lacked a good calf muscle pump action. While there were no varicose veins, the greater and lesser saphenous veins were large and generous conduits, at least by 3DVR imagery, confirmed on duplex (image below, white arrows).

veins — 3DVR showing presence of potential conduit

The extant arteries were smooth and plaque-free. I decided to harvest his lesser saphenous vein and through the same incision expose his distal superficial femoral artery and tibioperoneal trunk. While I anticipated some scarring, I was confident that the sections of artery I wanted to expose were easy to access because of some distance from the fused knee.

On left short saphenous vein was harvested then same exposure used to expose TP Trunk

The picture shows the exposure and reversed vein graft in-situ, using the segment of lesser saphenous vein. As in prior experience in redo surgery, you can never know if a dissection will be easy or hard simply based on fear or concern for breaking something. It’s not until you start bushwacking –carving through scar and dealing with extraneous bleeding will you learn whether it was easy or hard. You can only be certain it was necessary. The only hitch was the femoral artery while well exposed, was buried in scar, and I chose not to get circumferential control as I was fairly deep, and had avid backbleeding from a posteriorly oriented collateral that required a mass clamp of the deep tissues.

Will this work better? Don’t know but it has a good chance, and I think a better chance. It is a large vein oriented in a straight path over a short distance going from good artery to good artery. This is better theoretically than a long meandering bypass with smaller vein.

My First Intentional Stent Removal Case -Arterial Restoration

Posted on September 4, 2015September 4, 2015 by docpark

In 2007, at which I had performed about 20 standard EndoRE (Remote Endarterectomy, LeMaitre Vascular) cases over about two years, this patient in his later 40’s presented to me with ischemic rest pain of his right foot. He was a current heavy smoker who initially had severe claudication and a TASC D occlusion of his right superficial femoral artery. Prior to being referred to me, he had undergone a mitral valve replacement from which he recovered uneventfully. He then had treatment of claudication starting with iliac stenting and a vein bypass. He had undergone a femoral artery to below knee popliteal artery bypass with reversed greater saphenous vein which became occluded after being complicated by MRSA wound infections. When this graft developed problems at the distal anastomosis, he underwent revision with a jump graft from the arm. This graft went down after he developed MRSA infection of the cephalic vein harvest site. He then underwent SFA stenting with 5 femoral stents (at that time, long stents were not available), but these occluded and his access site was the nidus of MRSA based sepsis. He had had multiple hospitalizations for MRSA infection from phlebotomy sites when he presented. He had reintervention for in-stent restenosis, first with balloons, then an extra stent, then cryoballoon therapy, each episode complicated by MRSA infection. He presented with severe claudication and nocturnal rest pain. On exam, he had dependent rubor, elevation pallor and absence of pulses, despite having fairly benign anatomy on CTA.

There was two vessel runoff below a reconstituted popliteal artery, with stent occlusion and visible stump of the vein bypass.

My options included bypass with PTFE, cadaveric vein, endovascular recanalization of the occluded stents, or EndoRE. While considering the MRSA which had been extensively worked up prior to presentation by ID including TEE and multiple cultures, it was decided that he was firmly colonized with MRSA despite efforts at eradication, and PTFE was not an option. Cadaveric vein I have used in infections with acceptable short term results -never great long term except for one individual who I inherited from a surgeon in Kansas who maintained a decade of patency of a cadaveric vein to tibial artery bypass with coumadin alone. This patient was not likely to be so lucky. Endovascular recanalization with atherectomy versus laser was considered, but I had at that point become disillusioned with those modalities in such extensive disease.

EndoRE made the most sense because it was my observation in a prior patient in whom I had unintentionally removed a 4cm stent with plaque that stents are placed inside plaques and when you remove plaque, theoretically, the stents have a layer of plaque between them at the adventitia. Also, he had none of the extensive calcium that made regular EndoRE challenging. Also, it would be repaired with native tissues through a single groin incision, and covered with a sartorius flap. And that is what I did.

The common femoral artery was exposed and the SFA controlled. The plaque dissection was started and the ring fitted around plaque and stent. There was a little more friction than expected, but I did inject via a catheter cold LR with the idea that it would shrink the nitinol a bit. Also, the wire that guided the catheter did double duty as a dissector as I was subintimal with it. The rings traveled well to the end point which I achieved with little difficulty.

Vollmer Ring Dissector around plaque & stents

The end point was dissected and required a short self expanding stent. The patient recovered well and was discharged, but as in prior admissions, developed a cellulitis on the groin wound that resolved with Vancomycin, presumably with MRSA. A CTA done at that admission showed excellent patency and he had palpable pulses.

Three years later, he underwent intervention by one of my partners in cardiology at that time for a restenosis in the mid SFA and had ballooning and a stent -the second set of stents in this patient, and by the time I left Iowa, he was still patent and walking.

This operation fails with randomly distributed TASC A lesions that develop in sites of remnant smooth muscle. I think today, I would treat with a drug eluting balloon. Thrombosis is the other failure mode, but unlike PTFE grafts, there is no thromboembolism of the outflow, rather, the SFA thromboses with reconstitution of the original state, and is amenable to thrombolysis. Smokers such as this patient and those with limited outflow are anticoagulated with warfarin.

The Europeans call this now arterial restoration. The vessel is returned to its baseline state with a full complement of collaterals which are revived. Also, compliance is restored and I believe this plays a significant role in maintenance of patency. Also, as the native tissues heal, they return to a normal ultrastructure -I have taken pathology specimen with aortic punches to perform bypasses to the other leg from external iliacs treated so, and they were microscopically and visibly normal.

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