Does An Endovascular AAA-Stent Graft Induce Hypertension? We Need More Data!

Hi! Folks,

The purpose of this post is to encourage you to gather data if you are dealing with an abdominal aortic aneurysm (AAA), with or without an endovascular stent graft, or any other life-threatening condition for that matter. You never know, it might help.

Remember my early posts about how I discovered my abdominal aortic aneurysm? Much like Pauline [see comments], I noticed an abdominal pulse combined with an unexpectedly poor race performance. I also mentioned that when I went in for my stent placement, which probably saved my life already, I was normotensive (130/80), and a few weeks after the stent placement my blood pressure was 195/105 mm Hg. Never had that before, ever!!

I’m just coming out of a blood pressure (BP) funk, thus the gap in my posts over the last week. I thought that my post-AAA-stent BP problems were over, because a few months ago I was fooled by insufficient data, and not paying attention, into thinking that things on the BP front were fine. A week ago I went for a routine medical check and my BP was at 190/105 mm Hg, which immediately made me think of stroke, heart attack, blindness, and lovely things like that. It also frightened my family and friends, especially the two nurses, to death; they wanted to cart me to the Emergency Room, and we’ll see if they were right. As a researcher by nature, I ran some more measurements on myself, to find that my BP essentially hovers around 180/100, with a resting pulse 10 beats per minute faster than my usual 39-41. Interesting what this kind of information does to what I like to think is a calm, rational brain. Sure!!!!

I expect to be dead one day, but not yet, so my reaction over the following week went like this:  (1) dismay, (2) panic, (3) literature research, (4) more panic, (5) frustration with apparently slow medical system [but it is me that is panicking, not them, so I am not rational at that moment and they have many other priorities, and the wheels are in motion. That said, you still have be your own advocate, but not annoy as that slows things down and is not encouraging of rational thought], then (6) calmer thinking and analysis of the situation, and finally (7) realization that I need more information on the behavior of my hypertensive vascular system, i.e. I need more data. Such data might help my much appreciated medical professionals decide what to do if they are listening (which I hope they are!), and equally importantly it gives you a feeling of taking control, whether that is true or not, and such a feeling will lower your blood pressure.

After purchasing a high quality, ‘wrist blood pressure measuring device,’ using Deb as negative control (115/75), I then established that my resting but high BP is pushed up further by environmental stress to around 200/110, and it is lowered slightly by sleeping on my stomach instead of my back (read this somewhere). I then did some simple experiments with an n (group size) of one (Tim Ferriss approach) which appeared to demonstrate that (a) beets, known as beetroot where I come from, had no effect, and here’s the data:

Time                             HR         Systolic    Diastolic

Pre-Beets

7:15 pm                          56            179            92

Post Lots of Raw Beets

7:45 pm                          54            175            95

8:15 pm                          54            184            108

8:45 pm                         53            173            95

9:15 pm                          52            179            99

9:45 pm                         47            177            100

Woke up the next day hoping for salvation by beets

5:30 am                         58            191            109

No change! As a scientist I should repeat it three times, but I couldn’t look a raw beet in the face if I tried, plus all my bodily fluids are bright red, making me wonder if I have a bleeding disorder, so I move on:

(b) rest didn’t help, (c) caffeine still needs more work, and I am doing that [bummer], and FINALLY (d) exercise consistently reduces my blood pressure, whether biking or running. Here is an example data set:

I rest after waking up slowly, and then measure BP before climbing on my trainer bike (my old friend Quintana Roo, with Power Cranks and Computrainer!). Ride indicated as minutes x Wattage:

Time                             HR         Systolic    Diastolic

Pre-Ride

7:00 am                         51             181               102

During Ride

7:10 (10’x85W)            87            169                  91

7:20 (10’x120W)         98            160                  84

7:30 (10’x140W)        112            170                   79

Not statistically strong, but it happens every time. Best result was a systolic BP of 136. I now plan to work on optimizing the load times time response – got to give my heart and cerebral vasculature a break while my doctors work out what to do!

Yesterday I ordered a new Chez Ollie from Victor, as I plan to keep up my Ironman training for a long time to come.

Happy Friday,

Kevin

Comments

  1. Pauline Watson says:

    Hi,
    Interesting blood pressure data, and a coincidence that I was also looking at my variation with exercise today. One question, what were your values pre-stent? Also, is it the case that it is the diastolic one that is important in hypertension, and systolic varies throughout the day? For comparison, mine is normally 120/80 and I have a correlation with heart beat (on a treadmill) of:
    (bpm, d,s): (50,128,82), (53,112,76), (79,130,64), (98,144,80), (123,158,80), (153,174,80), recovery (92,158,90), (63,114,80)
    The BP goes down initially, as does yours, then goes up as the effort increases. I considered just running slowly to keep the BP down (less stress on Albus), but since it is only systolic that varies significantly, and only for the time exercising, I think I’ll continue running intervals!

  2. Kevin Morgan says:

    Hi! Pauline,
    Thanks for your comments and the data. Very helpful!
    1. Prior to my stent I had no history of hypertension and my resting pulse hasn’t been over 45 for several years. Since my stent most of my measurements, two of which were in doctor’s offices showed a significantly high BP and HR. After I recovered from AAA-stent surgery, I noticed that my heart was laboring all the time, which I put down to compliance changes in my high-pressure system. This feeling has been slowly diminishing since then, but it never goes away completely. I am going to see another cardiologist on Wednesday, and I am hoping that someone will get to the bottom of this so that I can get on my training for LPIM. I am going to do more load-BP experiments to find the optimal BP lowering wattage/duration, as that seems like a good thing to do. I’ll put worthwhile observations in posts to this site.
    2. I was planning to research diastolic versus systolic issues, but off of the top of my head I would say that the concerns are: (a) high systolic pressure could blow an aneurysm in my brain or elsewhere, or weaken the seal around the anterior end of my AAA-stent as the systolic pressure wave-induced expansion of the elastic laminae hits the anterior margin of stent which is not so elastic, whilst (b) my concern about a high diastolic pressure would be impaired blood supply to the cardiac muscle which is perfused during diastole [clever trick that!], due to increased compression of the capillary bed. I could have this all wrong, as I am no cardiologist. I think I’ll post this question on ‘The Athlete’s Heart Blog’ and ‘Cardiac Athlete’ once I’ve had my second morning cup of tea.
    When it comes to workouts that induce a high systolic pressure, be careful, as your AAA could be fragile. I think that it is not so much the load as the rate at which the load is applied. It is clear that vascular bed resistance drops with exercise, at least in some places, but this takes a little while. So! I would gradually increase load based on experiments. I was planning to try immediate load (say 160-200 Watts) versus ramping up gently, to see what my maximum systolic pressure is in each case. We should develop a protocol for this approach, designed to minimize systolic risks, as we are all a little different ‘cardiovascularly.’ Let’s see what we can find in the literature, and evoke from various chat rooms.
    Bottom line, in my ill-informed opinion – gently ramp up the load before your intervals.
    Cheers,
    Kevin

  3. Kevin, I sent you an email with this. Below is an abstract from PubMed of an in vitro AAA/stent graft model demonstrating (quite convincingly) that both rigid and non-rigid stent grafts induce hypertension (HTN). –EB

    http://www.ncbi.nlm.nih.gov/pubmed/17360221

    Med Eng Phys. 2008 Jan;30(1):109-15. Epub 2007 Mar 13.

    Evidence suggests rigid aortic grafts increase systolic blood pressure: results of a preliminary study.

    O’Brien T, Morris L, McGloughlin T.

    Centre for Applied Biomedical Engineering Research and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
    Abstract

    Abdominal aortic aneurysm (AAA) is a serious complication of the aorta and is treated using vascular bypass grafts. Two main classes of graft are available to treat AAA; grafts implanted by open surgery and stent-grafts implanted using minimally invasive endovascular techniques. Both classes of graft consist of an aortic section which bifurcates into two iliac sections. It has been hypothesized that implantation of aortic grafts and stent-grafts serve to significantly increase abdominal aortic pressures. In this study, an open-loop computer-controlled pumping system was built to produce physiologically realistic pressure and flow-rates. Models of a compliant abdominal aortic aneurysm, a compliant walled graft and a tapered graft were manufactured using an injection moulding technique and fused deposition modelling was used to create a rigid walled graft. A specific transient flow-rate waveform was then applied at the inlet of each model and the resulting pressure waveforms 30 mm upstream from the bifurcation was recorded. Peak pressure measurements were recorded over the course of the pulse for each model. The compliant aneurysm model was found to have a systolic pressure of 107 mmHg while the complaint graft model was 153 mmHg. The rigid graft model had a peak systolic pressure of 199 mmHg. In the tapered graft, the peak pressure dropped to 142 mmHg. The data suggests that implanting a graft model in place of an aneurysm model in an in vitro flow circuit can increase the pressures recorded upstream from the iliac bifurcation and that tapered grafts may alleviate this problem.

  4. Hi! Eric,

    This abstract, which I failed to find in spite of extensive searching, is very much appreciated. The information provided opens doors to a rational approach to therapy. I have contacted the authors of this abstract for comments on my hypertension, in addition to communicating with a number of other vascular physiology researchers, including Raven (see article in today’s post). It is surprising how much this abstract has reduced my state of tension.

    Very much appreciated, and I look forward to your coaching.

    Thanks!

    Kevin

  5. Concerned Daughter says:

    My mother had the Endurant Stent by Medtronic placed for her AAA in January of this year. Prior to surgery, she always maintained a good, healthy BP most often on the lower end of normal. After the stent placement, her blood pressure has topped out around 220/118. She was hospitalized about 4 weeks post-op for stroke like symptoms (slurred speech, confusion, severe headache, etc..). She was placed on BP meds and now averages a BP of 165/90 or so. She still continues to have headaches on occasion and was most recently hospitalized for chest pain and shortness of breath. Heart tests checked out ok…but they still have not done an MRI (or CT -not sure which test they use) to check the placement of the stent. She now was found to have
    blocked carotids but surgery has been postponed due to the issues with her BP. Our family is 110% convinced that her issues with high blood pressure are directly related to the placement of the stent, however the doctors are reluctant to agree. We were told of all the risk and benefits to the stent rather than open surgery, but were never told that this could cause high blood pressure. Would be interesed in hearing from others who have experienced this….Thank You!

    • Kevin Morgan says:

      Hi! Concerned Daughter,

      Thanks so much for this information on your Mom, as her situation exactly parallels mine, including the highest post-stent BP (220/120) and the degree of diminution of BP with meds, to the 160/90 range. Mine was further corrected by consistent training at fairly high level, which brought my BP to normal or highish normal. I also had no pre-stent history of hypertension, in spite of regular annual health screening. I posted my AAA-stent-induced hypertension information on this blog, previously. We now, I think, have sufficient evidence to suggest that AAA-stent grafts can induce hypertension, which should be investigated further, and certainly should be prepared for before surgery, and addressed after surgery by regular BP checks. I will inform Medtronic and Cook of this issue. Thanks so much, and I’ll keep you posted on their response.
      I am grateful for my stent, which most certainly saved my life, as my AAA was about 7 cm in diameter, and one look at the CT convinced me to get this treatment ASAP. I think that in my case it was life saving. I failed to convince three cardiologists that my stent had induced the hypertension. The potential for effects on BP make total sense if you think about the underlying fluid mechanics and related the regulatory circuitry, plus the evidence from the laboratory in Limerick (see cited article in my previous posts!).

      Very much appreciated, and best wishes to you and your Mom!

      Kevin Morgan

    • Hi concerned daughter, how’s it going now? -kevin

  6. The information contained herein reflect my BP problems since receiving my stent. Saved my immediate life, not so sure about the longterm. And no physician will consider the stent as the cause, nor do they have any other cause!

    • Hi Paul, NO ONE will listen, if you have normal renal function.
      I told my story over and over to cardiologists, and they all said it was due to renal dysfunction, even though they couldn’t find any renal dysfunction. My frustration led to my filing an adverse event report with the FDA https://athletewithstent.com/2011/04/22/aaa-stent-fda-adverse-event-correctable-hypertension-and-the-role-of-high-technology-in-my-life-recently/ You will be my third case (one being me). Mine jumped from normal to 220/120 after the stent. NO ONE would listen. Drove me nuts. Then I found the paper from Ireland predicting this, and no one would read it. I called the guy who published the work and he wouldn’t talk to me.
      Tell me your history.
      Lisinopril combined with exercise worked, and as I expected it finally self-corrected by about 90% after about 18 months.
      If you don’t have renal dysfunction, it’s the bounce back wave confusion.
      Let me know more, and thanks for writing, and get on an ACE inhibitor, or something other than a beta-blocker (that’s what I did, anyway).
      Thanks for writing.
      Cheers,
      Kevin

    • PS I even carefully reported my hypertension story to Joe Graedon on the People’s Pharmacy, explaining that I had no renal dysfunction detected by CT/fluoroscopy, or blood chemistry. His reply was straight party line: “It’s due to renal dysfunction.” This can occur if the stent covers the renal arteries, but I presume that in your case, and most certainly in mine that is not the case. His response really pissed me off, which led to my report to the FDA, which I’m sure went the same was as the Ark in Raiders of the Lost Ark. My other case was a lady suffering from hypotension for years, until she had her stent, when her BP jumped to 220/120, and she was very frustrated when her physicians said the same as mine, “You must have had hypertension already, but didn’t know it. It’s due to renal dysfunction.” It is impossible to get these people to listen. I think it’s because they have no real understanding of fluid mechanics – excuse my rant. Cheers, Kevin

  7. dirk bruere says:

    Hi

    Same experience here, some 4 months after extensive grafts. Saw the doctor a couple of weeks ago and BP was 220/110. No matter what I did in the intervening weeks I could not get it down to sensible levels, so got an ACE inhibitor and it’s now coming down.
    In your experience, does the BP decrease naturally over time of am I on pills forever?

    For your amusement:
    https://medium.com/@dirk.bruere/black-balls-hallucinations-on-the-ceiling-and-euthanasia-my-hospital-adventure-f910b155344d#.lnf11md8f

    • HI Dirk.
      How about that!
      I wondered when another case would come in. I filed an adverse event report with the FDA – NO ONE would listen. They said it was due to kidney problems, with no evidence of kidney issues. You are the fourth I know of, including me. Bounce back wave, for sure.
      It’s a crap shoot, rare adverse event, based, I suspect on aortic fluid mechanics (don’t waste your time trying to explain this to cardiologists – they don’t listen).
      Mine took about 18 months to completely correct, but my pulse never returned to the pre-stent 38 (I train a lot).
      I’ll write a short post about his, as a reminder. Off to read your link!
      Thanks so much for the comment,
      kev

    • HI Dirk, I enjoyed your article so much, I took the liberty of posting the link on the AAA Awareness Facebook page. Hope you don’t mind! kev

  8. glen roddel says:

    I have elevated blood pressure . Had stents put in 2 months ago . (Medtronic) My AAA has not come down in size. (around 6 CC) I wonder what the high blood pressure will do to the AAA and the stent seal. Also what type blood pressure Meds. Ace inhib. are best. It’s hard to get info from doctors as I beleave that some don’t know. Blood press. 175/80 Tried to meds so far no change Thank you and any info would help Glen glenroddel@gmail.com

    • dirk bruere says:

      I have a beta blocker prescribed. I take 25mg Carvedilol twice a day. No noticeable side effects.

      • Hi Dirk.

        We all respond differently to drugs. Some see no adverse events, while others suffer severely, from an identical regimen. I’m glad to hear you’re fine. The one side effect I didn’t like, as an active athlete, was the suppression of heart rate. This would make training extremely difficult.

        It’s always a risk benefit decision, in which the patient should be actively involved.

        kev

    • Hi Glen, this is an interesting issue.
      My blood pressure jumped from normal to 220/120 two weeks after AAA stent insertion. I researched it, and concluded it would self-correct to a large degree, in time. This turned out to be correct. I failed to have an intelligent conversation about this issue with the 6-7 cardiologists I attempted to discuss it with. I elected for an ACE inhibitor, based on reading all potential side-effects.

      THE THING ABOUT SIDE-EFFECTS: We all respond differently. Some see no adverse events with drugs while others might even be confined to a wheel chair, for instance: http://www.dailymail.co.uk/health/article-3300937/Crippled-statins-Cholesterol-busting-drugs-left-David-wheelchair-doctors-insisted-taking-them.html. Having seen the muscle lesions induced by statins first hand, in rats, as a pathologist, I believe it.

      It’s always a risk benefit decision, in which the patient should be actively involved. Doctors are often right and often wrong on such matters.
      The only problem I have with Lisinopril (ACEi) is the fact that it interferes with my temperature control, making my Raynaud’s much worse. It triggered a dangerous case of heat stress in one race a few years ago.
      The answer is always to understand the drug, and decide based on other aspects of your life. I know this sounds vague.
      We live in our bodies all the time, they doctors see us at best briefly.
      kev

      • Thank you Much Kevin My BP has came down with Lisinopril The Low side 55 to 65 worries me. My doctor tried to other BP meds. with no results. Maxing out dosage on both. My doctor for stent placement fail or didn’t know about my BP proplems. even after my first ck. up.. I told him that after ck. out my PB was 205/110 Pl/118. He seem a little indeferent about it as my pressure was down from meds to 155/95 . He pass it on to my fam. doctor. who knows little about AAA stenting Against his advice I went on Lisinopril. Just ck.it 139/59 not blowing in corks anyway.. But the low side does worry me Thanks Again Kevin Your friend Glen Roddel

        • Hi Glen, it’s odd that your diastolic is so low. I need to read up on that. The heart receives blood during diastole, using residual pressure in the proximal aorta. I forget, do you have an ascending and abdominal aortic enlargement. Loss of tone in the ascending aorta might be a cause. That said, I’m guessing. My systolic and diastolic pressures tend to track together. I strongly recommend that you study these issues. They are not complex, it’s just that one has to learn the jargon. Education is one essential key for survival in our situation. I’ll look into this and get back here. Right now, I’m traveling. Hang in there. Remember that worry is an enemy, not a friend, unless it is appropriately directed. Kind Regards, kev

  9. Hi Kevin,

    Thanks Kevin it was very reassuring to hear that my recent experiences with EVAR repair and blood pressure are not unique. As a reasonably fit 65 yr old ( walking,biking,swimming) I was always happy with my 130/80 BP which was remarkably consistent over time. 3 weeks ago I had the Evar repair and a couple of days ago – having allowed some time for healing and settling – I checked my BP and was shocked by the 160/102 reading which was confirmed yesterday by a reading of 190/107 anxiety creeping in no doubt. Like you I started to worry about brain bleeds and all the other joys hypertension can bring , so I will be seeing the Radiology Consultant who did the EVAR repair tomorrow to get his opinion about the way forward, if he casts any light on current thinking I will let you know. Kind Regards Ian

    • Hi Ian, I’m glad you found my post on this interesting issue. It’s not common, I think, though no cardiologist will even discuss it with me. If you look at my original report, you’ll see that an engineer in Ireland predicted the systolic increase. My resting heart rate went from 138 to 155+ (never to come down) and my normal blood pressure (130/80) jumped to 220/120. Cardiologists said is was due to my kidneys.

      I showed copies of the Ireland paper (all fluid mechanics work, one of my background specialities) to several cardiologists. Same response every time. A glance, throw it aside and say, “It’s due to kidney disfunction.” All kidney tests are consistently normal. That’s why I filed the adverse event report with the FDA, which I’m sure went the way of the Ark in Raiders of the Lost Ark.

      My advice: don’t take beta-blockers or statins. My BP corrected with ACE inhibitor (Lisinopril, 10 mg) and continued exercise. I’m also on a plant-based diet. The problem with the ACE inhibitor is interference with thermoregulation. If my systolic BP is less than 160 I don’t take them. Haven’t for months, and I’m back in training at age 75.

      That’s your call of course. I’ve met very few cardiologists that I trust – most are horribly arrogant. Maybe you have a good one.

      Kind Regards

      kev

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Disclaimer: As a veterinarian, I do not provide medical advice for human animals. If you undertake or modify an exercise program, consult your medical advisors before doing so. Undertaking activities pursued by the author does not mean that he endorses your undertaking such activities, which is clearly your decision and responsibility. Be careful and sensible, please.