Does Gravity have anything to do with it?
> On Jan 14, 2015, at 8:28 AM, Kirk W Beach <[log in to unmask]> wrote:
> The abdominal aorta has been considered, explored and modeled to address this question without reaching a solution or consensus, so far as I know. I'll share my thoughts here in the hope that flownet members will try to accumulate supporting or refuting data.
> 1. The renal arteries drain 1/4 of the cardiac output from the aorta.
> 2. At rest, below the renal arteries, diastolic flow is ZERO, but above the renal arteries diastolic flow is forward.
> 3. High shear rates at the artery walls cause the arterial lumen to dilate. This is exhibited in cases of increased flow after dialysis access surgery, lower extremity vascular obstruction and collateral development, and, perhaps even in the formation of the carotid bulb (if the external carotid artery, which sometimes has reverse diastolic flow, has a large angle to the main axis, then the location of the carotid bulb w/r the bifurcation flow divider is more distal).
> TAKING THE ABOVE AS TRUE, then if there were a perpendicular side branch on the abdominal aorta that formed a diastolic nozzle jet crossing the lumen, this would cause the opposite wall to bulge.
> 4. People with atherosclerosis have a higher incidence of Abdominal Aortic Aneurysm than people free of atherosclerosis.
> 5. The superior mesenteric artery is the proximal end of the mesenteric artery, the inferior mesenteric artery is the distal end.
> I HYPOTHESIZE THAT an inferior mesenteric artery with a orifice stenosis will have little systolic inflow, but that in that case, the superior mesenteric artery will provide systolic inflow to the entire mesenteric artery which will arrive at the inferior orificial stenosis after transit through the length arriving during diastole and provide a cross axis jet in the abdominal aorta that will cause the opposite wall to dilate forming the aneurysm. PLEASE HELP PROVIDE DATA FOR THIS SPECULATION.
> When you see an AAA, especially one that is between 30 and 40 mm diameter, take some extra time (even though I know that you don't have any) and look for the IMA. Record the spectral waveform from the SMA and IMA.
> The SMA should have continuous forward flow (this will depend on the time and type of previous meal) but the IMA, if this theory is correct should have a stenosis, with flow reversal during diastole.
> MAYBE by looking at the aortic lumen, near the IMA origin, during diastole, a cross stream jet can be visualized.
> To assure that the timing of the waveforms are known, it is best to perform these examinations with ECG.
> I look forward to your thoughts and data to refute this hypothesis.
>> On Mon, 12 Jan 2015, Mina Tohid wrote:
>> What are the possible reasons for Infra renal AAAs to be the most common one?
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