At the Intersection of Art and Science

tube graft

I taught myself to draw during medical school when I couldn’t figure out the three dimensional relations of structures. I discovered that if you just draw the shading of an object, it pops out in three dimensions. Over the years, I took to carrying little notebooks to sketch out anatomy and proposed operations for patients through this medium. While I found this to be a handy tool that I used only occasionally, since moving to Abu Dhabi, where much of my communicating is done through an interpreter, my drawings carry a much greater weight as direct communication of my thoughts and intentions.

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Drawing helps the patient and family understand the unseeable. It gives form to words that are often confused like blood vessel, graft, stent, artery, and vein.

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What is informed consent when patient’s cannot describe their problems to their friends and relatives what the problem is and what is going to be done about it?

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I usually draw with the pen in my shirt pocket and some copier paper, but sitting down and doing a proper sketch is soothing and very helpful for me as the surgeon to previsualize the goals that I have to reach during an operation to take the patient across the finish line. During meetings and conferences, I sketch into one of those fancy bound notebooks that I collect.

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Funny thing is I was doodling during class as a kid, but it was spaceships, not aneurysms.

While pencil and markers do a fine job, the real magic is in using tablet based sketching software, using layers, to build serial images of the steps of an operation.

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I am increasingly tempted to use these images as my operative note, but understanding that words are needeed for billing, I comply. Even so, I find it helpful to put these illustrations on my EMR notes, because it allows everyone to see and understand what I saw and what I did. I leave you with some of my illustrations with attached comments.

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Long segment disease stents in their natural occluded state

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Our best shot

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The nutcracker
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The fractal
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Hybridized aorto-bi-iliac revascularization
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Retrieving the unretrievable embedded filter
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3 step treatment of a type II thoracoabdominal aortic aneurysm
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Dysphagia lusoria, treated
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Targets under the ulcer
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I’m not sure this really works
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An off pump CABG for a vascular surgeon
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Phase 1

Phase 2

Enough Flow!

I got a call about a graft fistula that had a stenosis. “Where?” I asked. At the arterial anastomosis, the velocities were high -500cm/s. My next question was, “is there a problem with dialysis?” The response was, “no.” I reassured the caller and then asked what the velocities were in the mid graft. Around 200cm/s.

Which made me pull out a sheet of paper to do some math. I have to confess, after learning higher level math and fluid flow during college, I had to think about it. The question was, for a pipe that goes from 4mm to 7mm in diameter, what is the ratio of velocities in the smaller pipe compared to the larger section?

The diagram above shows the calculations. This makes a lot of assumptions about the fluid that aren’t necessarily true but I went to medical school, not grad school.

The algebra comes out to the calculation that the velocity in the 4mm segment will be 3 times faster than in the 7mm segment. Which is pretty close.

At the end of all this, it struck me that I needed no other more relevant information than the answer to, “is the dialysis going well?” The velocity numbers for the proximal anastomosis aren’t helpful except under the condition “yes, there is a problem with dialysis.”

There is only the Boolean, Dialysis Good, true or false. Enough flow? implies we know the exact number, a magic volume flow number. The problem with focusing on flow is that there is a problem with too much flow. Arteriovenous shunts are like adult ventriculoseptal shunts (VSD). They burden both sides of the heart. It’s like hitching a trailer on a car. Some cars like SUVs are fine for this, but imagine hitching a boat on a tiny car, which what happens to patients with bad hearts and renal failure.

We don’t have many good options in heart failure or severe systemic atherosclerosis than a catheter. Catheters are just awful, but in heart failure, any amount of flow may be detrimental.

I recently saw a patient with no fistula flow, but a patent and aneurysmal segment of cephalic vein fistula remained and inflated with expiration (above). The outside hospital had placed a tunneled catheter in the right internal jugular vein, but it failed to draw enough blood and they had taken to accessing the cephalic vein with a 14g needle and returning the dialyzed blood via the catheter. Here is a case of the nonflow access. The fistula has gone down at the anastomosis several months before -this is rare to have both a widely patent cephalic vein and a closed anastomosis.

The draw from the vein worked well because there was a siphon to the right atrium and on dialysis days, she was fluid overloaded enough to keep the remnant cephalic vein inflated.

The lack of arterial flow meant that return couldn’t happen in the same vein, but imagine if she had the same in the other arm or better, on the thigh.

Which then made me think that a dilated and varicose thigh vein with a patient sitting slightly upright would be fine for access. Why not? And accordingly, in heart failure patients, high venous pressures are the norm especially in the legs when the head is up. Can we make an access for heart failure patients that takes advantage of their fluid overload?

It would work like this. In both thighs, the valves in the saphenous vein are cut using a endoluminal valvulotome, particularly the anterior thigh tributary. Then you wait. The combination of heart failure and bipedalism will result in huge veins. Once the veins are huge, you could make a very small fistulous anastomosis, but I don’t think it would be necessary.

Some people will have large superficial veins that will allow for dialysis access even without a fistula. Crude drawing below if dilated veins created on the thigh.

Knee high stockings, of course.

Let’s agree to call this the Abu Dhabi sump.