Category: POTS

Categories
Commentary edema Gonadal Vein interstitium Lifestyle Lymphatic lymphedema May Thurner's Syndrome median arcuate ligament syndrome Nutcracker Syndrome Ovarian Vein Pelvic Congestion Syndrome popliteal artery entrapment syndrome postural orthostatic tachycardia synrome POTS superior mesenteric artery syndrome SVC Syndrome Uncategorized venous intervention

The Consequences of a Bipedal Lifestyle

Talk I gave to  Oxford University Vascular Surgery

In George Orwell’s Animal Farm, under the dictatorship of the alpha pig, Napoleon, the pigs who represented the nomenklatura of the farm chant the slogan “four legs good, two legs better,” after initially declaring “four legs good, two legs bad” during their revolution. They clearly understood the luxury afforded by a bipedal lifestyle, because in rising on two legs, you get arms and hands which can do many things like caress a baby or wield a cudgel. What the pigs in the parable weren’t realizing were the consequences of a bipedal lifestyle.

When Lucy, the Australopithecine, bipedal hominid ran about on two legs, she did have the use of two arms and hands. Possibly an adaptation to living in tall grasslands with few trees, the ability to stand tall like meerkats, allowed the biped to see far into the horizon for big cats who probably loved the big brained hominid for the high calorie meal inside the hard skull -many fossils from this time show puncture marks from the incisors of medium to large cats.

The walking and running put heat stress on the brain, and the tool use which happened incredibly early and is observed in the chimpanzee, likely drove the selection for a larger brain (more neurons will allow for one to lose some neurons to heat stress but stay in the game), but it created likely the first problem for our ancestors -discharging a cantaloupe sized head through a pelvis that was small to begin with but now also reshaped for bipedalism. We still suffer from a childbirth process that no other mammal faces -birthing a less than fully cooked baby -a tradeoff for that giant head.

Standing also meant the load bearing was shifted 90 degrees with long term consequences. For our ancestors who only lived about 20-40 years if the chimps are correct, this wasn’t a big deal as arthritis and tendinitis didn’t preclude eating and breeding and didn’t affect them until they were old. But with modern sanitation and social structures,  we are reaching 100 years and the majority of the problems of the integument -the bones and ligament, the low back pain, the sore knees, the ratchety hips, can all be explained by our bipedal lifestyle. Your arm is 30-50 pounds of meat and bone and supported only by muscles off your spine, and your blood vessels and nerves traverse a narrow passage through these muscles and your first rib. Your diaphragm with 5-10  pounds of heart, lungs, and blood sits on first branch artery off of your aorta. Your veins, designed to drain blood from your organs, have to do so with over a meter of static water pressure and your sump pumps only work when you are walking. Muscles and their tendons are stretched tight in the odd way that upright walking and running demands, compressing blood vessels and nerves. All of this weight is put on your feet which have to deal with up to a ton of pressure with running…

I’ve talked about this concept many times before but never had a chance to put it together like this talk. I may write an article. Looking back, I did this blog post (Link).

I am grateful to Ms. Mei Nortley and Mr. John Raphael for the invitation to give this talk.

Categories
iliocaval venous May Thurner's Syndrome postural orthostatic tachycardia synrome POTS Uncategorized Venous venous intervention

POTS+May-Thurner’s Syndrome: Rare Disease Causes Rare Disease?

preop-mri_3

The patient is a younger man in his twenties who began having dizzy spells associated with near syncope and tunnel vision. He was previously an athlete and was fit and never had such episodes -he had a resting heart rate typically in the 60’s or lower. Workup for arrhythmias was ultimately positive for POTS -postural orthostatic tachycardia syndrome and he was referred to Dr. Fredrick Jaeger of our Syncope Clinic. Tilt table testing the demonstrated the reported tachycardia over 140bpm while upright rising from 60bpm while supine. A radionuclide hemodynamic study (Syncope Radionuclide Hemodynamic Test) showed 54% of his blood volume pooled in his left lower extremity and lower abdomen with upright posture. Air plethysmography (PHLEBOTEST) showed abnormal refill and fill times in both legs and a duplex of the legs showed deep venous reflux in both legs. MRV revealed narrowing of left common iliac vein by the overlying right common iliac artery (May-Thurner’s Syndrome, MTS), and this was where the patient came to my clinic.

The MRV, shown above and below showed the typical pathoanatomy for MTS, but the patient had no symptoms related to left leg swelling, DVT, or varicosities. He did have a reducible left inguinal hernia which was quite tender.

preop-mri_1

After some deliberation, while not promising anything regarding his POTS, I agreed to proceed with treating his pathoanatomy. Discussion with Dr. Jaeger revealed this: normally about 20% of blood volume parks in the legs with standing which is rapidly dissipated with normal calf muscle pump action. In a subset of patients with POTS, there is a 30-40% maldistribution of blood volume into the legs which may or may not drive the autonomic responses leading to POTS. He has never seen a study result showing a 54% distribution.

It made physiologic and anatomic sense to me to proceed with a venogram and intervention, but I confess I was dubious about any affects I might have on the patient’s POTS and I informed him of it. Also, I recommended seeing a general surgeon for his hernia.

Venography showed obstruction of his left common iliac vein as evidenced by the filling of pelvic and lumbar collateral veins.

preangio

Intravascular ultrasound showed the narrowing better and more directly (panel below). The right common iliac artery narrowed the left common iliac vein severely.

preop IVUS.png

A 22mm Wall Stent was positioned across this and dilated with a 22mm balloon in the IVC and an 18mm balloon in the iliac vein. The resulting venogram showed resolution of the obstruction with collateral veins no longer visualized (below).

post-intervention-angio

But again, IVUS demonstrated more directly the result (and illustrates the importance of having IVUS available for venous interventions).

post IVUS.png

The patient was discharged after procedure on a baby aspirin only. He subsequently underwent laparoscopic inguinal herniorrhaphy and returned to my clinic about a month later. His followup duplex showed a widely patent stent and normal flows in the left iliac venous system.

followup duplex.jpg

Surprisingly -the patient declared that he was cured of his POTS. He said since the stents went in, he has not had any more episodes of near syncope, dizziness, tunnel vision, nor weakness requiring lying down to rest. His wife confirmed that he was a flurry of activity over the holidays that was surprising considering how debilitated he was before. This is astonishing to me.

But it should not be a surprise given this: if the POTS symptoms were the result of autonomic dysregulation, a breakdown of the feedback control loop, there were only several places this could be a problem.

img_3793

The pathology, the MTS, explains the POTS in this instance very nicely. Because the problem was in the cardiovascular system part of the diagram which I can fix and not the autonomic nervous system control element, which I can’t fix yet, a solution could be tried. This was not an asymptomatic compression of the iliac vein which we do encounter as an incidental finding. It seems to be POTS caused by MTS, and cured for now by treatment of the MTS.