Categories
amputation bypass Commentary PAD trauma

When Better is Better Than Good

original bypass

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:

  1. 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
  2. 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.
  3. 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.
  4. 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.

intervention

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.

IMG_6478
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. 

Categories
bypass PAD techniques Wounds

Deep rescue from a hospice: saving a patient from hip disarticulation with advanced hybrid inflow procedure and vein bypasses

PREOP.001

The patient is an elderly man who had bilateral above knee amputations after failure of aortobifemoral bypass grafts at an outside institution. Unfortunately, he had no femoral pulses and his amputation on the right broke down (image above). His left stump had erosion of his femur to the skin with rest pain as well, but was at least covered by skin for now. He was declared too sick for hip disarticulations and was sent to a hospice where he failed to pass away. After a year there, he was sent to us for an evaluation.

He was suffering from rest pain and had complete breakdown of the skin over his amputation stump. More worrisome was the development of gangrenous scrotal and decubitus ulcers which were small but persistent and also foci of pain. CTA showed the following:

PREOP CTA.001

The aorta was occluded below his renal arteries. An AV fistula near his common femoral vein lit up his right iliac vein on the CT above. He had had a prior aortobifemoral bypass but this was occluded. Gratifyingly, it was anastomosed proximally end to side, giving us options. As with any revascularization, we had an inflow source -his aorta, and several potential outflow sources (CTA below, contrast filling iliac vein from AVF’s).

OUTFLOW.001

In particular, his distal profunda femoral artery showed promise. Vein mapping revealed a short segment of basilic vein in his arm to use as bypass, but we needed inflow from the aorta.

I have come to appreciate two things about aortoiliac recanalization. First is that passing the wire antegrade is far likelier to stay in the true lumen at least in the aortic inflow segment -retrograde wire passage inevitably dissects the occlusive aortic plaque and reentry into the true lumen of the diseased aorta is just as challenging as in the leg. The second is vein bypasses have excellent patency in challenging conditions -you just need excellent inflow and an arterial bed to perfuse.

My plan was to cross the aortoiliac occlusion with a wire from the left arm. Once the right iliac system was entered, it didn’t matter if I was in a subintimal plane. The wire could be seated in the common femoral artery to access with a surgical exposure. Once this was done, my intention was to perform remote endarterectomy of the external iliac artery and stent from the aorta to the common iliac artery. The endarterectomized external iliac artery would be the inflow source of a later staged ilio-cross femoral bypass to revascularize his left AKA stump. The common femoral artery at its origin would provide inflow to a short vein bypass to his profound femoral artery.

The wire passed readily into the right iliofemoral system and a groin exposure and common femoral arteriotomy allowed me to retrieve the wire which had been passed from the left arm. A remote endarterectomy was performed over the wire which I do to ensure access in case the artery ruptures (specimen below).

OR IMAGES.001

This allowed me to place a sheath into the right iliac system in the now reopened external iliac artery. Balloon angioplasty of the aortoiliac segment created working space for placement of balloon expandable stents from the infrarenal aorta to the common iliac artery, restoring an excellent pulse in the right groin.

The profunda femoral artery was encased in scar tissue, but following the occluded PFA from the CFA, I was able to expose an open segment and cut it open in the scar tissue. There was back bleeding, and I controlled the artery by placing a small Argyll shunt into the artery and reperfusing it from the recanalized right iliac system.

OR IMAGES.002

The Doppler flow in the shunt was excellent, suggesting great outflow potential. The bypass was performed over the shunt with reversed basilic vein. Completion arteriography showed excellent flow.

PLANNING SLIDE.001

The amputation stump was debrided of dead bone and muscle and the graft was covered with a sartorius muscle flap.

OR IMAGES.003

Before and after images are shown. The remaining open wound granulated well, and ultimately accepted a split thickness skin graft. His scrotal and decubitus ulcers healed as well (below at 6 months post op).

IMG_2380

His left AK stump subsequently degraded while he recovered so three months after this operation, he underwent a right external iliac to left profunda femoral artery bypass with cadaveric vein.

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I don’t like using cadaveric vein, but we really had no options. The right external iliac artery was approached through a right lower quadrant (transplant) incision and a punch biopsy of the artery revealed only normal adventitia on pathology. The EIA was soft and sewed well -essentially a normal artery brought back from the dead. The left profunda femoral artery was large after endarterctomizing its origin and accepted the bypass flow well.

The mortality from hip disarticulation in the setting of gangrene and infection is very high, and I feel that standard approaches to this problem -prosthetic axillo femoral bypasses, thoracobi-femoral bypasses, in the setting of advanced infection and gangrene were unlikely to succeed. In over 1.5 years of followup, everything has remained patent, and the patient lives independently.

Categories
bypass PAD

Diastolic Pressure Traps and Valve Flutter in Reversed Vein Bypass Grafts

diastolic pressure trap 1

AUGUST 15, 2008 6:52 PM

The patient was originally bypassed for ischemic rest pain due to femoropoliteal occlusive disease. He had an occlusion of his popliteal artery with reconstitution of his below knee popliteal artery. I performed a femoro-posterior tibial artery bypass with reversed saphenous vein.

In followup, he developed at worsening stenosis in the distal graft at around 10 months post-op. Arteriography showed a moderate stenosis due to a valve that appeared to close. It was reported retained valve cusps which was strange because the vein was reversed. The flow was noted to be sluggish in the distal runoff, without a distal anastomotic stenosis. He was taken to the operating room, and this valve station was exposed and it had a severe stenosis due to valvular hypertrophy. This was repaired with patch angioplasty. At that time, I thought that this had developed due to a dynamic stenosis. No other stenoses were seen at that time.

In followup, after an initial period of two months without symptoms, the patient developed claudication that worsened. Graft duplex showed a severe stenosis in the mid graft. This was a valve station that was proximal to the previously treated valve station.

diastolic pressure trap 3

I took him to the operative endovascular suite, and arteriography showed a severe stenosis (image above, right) due to a hypertrophied valve. .

On review of the literature, I find that Tullis, Strandness et al. found 11 of 66 (17%) reversed saphenous vein bypass grafts had functional valves, with 50% of these developing  >50% stenosis, with a mean time to recognition being 10 months [ref 1]. In a followup study, Strandness’s group found that valve related revisions composed 16.7% of all graft revisions in reversed vein bypass grafts, while none of the revisions for in-situ grafts were valve related. No specific valve features, they concluded, could be identified as a high risk [ref 2].

Robiscek et al [ref 3] performed intraoperative flow studies and found that under conditions of low graft flow, pressure traps occurred in reversed vein grafts. When diastolic pressure in the vein segment distal to the valve is greater than the systemic diastolic pressure, the valve closes.

This patient does have sluggish outflow due to tibial arteries that are severely disease. I believe this causes a pressure trap, but I don’t believe it is a sufficient condition for development of valvular hypertropy resulting in a stenosis.

I think that a second factor is fluttering of the valves due to turbulence. The valve cusps are in a widened segment of vein, and there is naturally turbulence that occurs -this may cause the valve leaflet to flutter like a flag in a stiff wind and cause intimal hyperplasia.

diastolic pressure trap 2
Outflow disease causes valve closure in reversed vein bypass grafts. These valves are also susceptible to turbulent flow.

The concept of a pressure trap is that during conditions of low graft flow, the diastolic pressure in the distal graft creates a gradient across a valve, resulting in closure and stagnation of blood flow. At the same time, at the onset of systole, the valve is partialy closed, and is subject to Bernoulli effect.

This is supported by the pathology which shows hypertrophy of the resected valve cusps.
diastolic pressure trap 4

This model would predict another stenosis at a more proximal point at some later date if the patient has another valve station.

While I still reverse the vein when I bypass, I am cognizant of vessel sizes and won’t reverse if there is too great of a taper in the vein diameter. I also think that not reversing to diseased or single vessel tibial runoff may be a way of avoiding this problem.

References

1. J Vasc Surg 1997;25:522-7.

2. J Vasc Surg 2001;33:369-74

3. J Cardiovasc Surg 1999;40:683-9.