Dear 850csi,
Thank you for your question. As you are aware, any information I
provide is no substitute for direct medical examination and advice.
Aside from the medical history you describe (quad heart bypass and
aortic valve replacement), a difference in systolic blood pressure
between the arms of more than 20mmHg (millimeters of Mercury) occurs
in about 12 to 18.4% of the population. Here is a free article from
the British Medical Journal that discusses this issue
Clark CE. Difference in blood pressure between arms might reflect
peripheral vascular disease. BMJ. 2001 Aug 18;323(7309):399-400.
http://bmj.bmjjournals.com/cgi/content/full/323/7309/399
An excerpt from this journal comment addresses your question:
?The causes of a pressure difference between arms are unclear.
Harrison et al found fewer differences with intra-arterial
measurements than with indirect techniques, suggesting that variations
in the measurement techniques or the soft tissues may play a part.2
For some patients the difference is vascular in origin. This may be
due to characteristics of flow in a normal arterial tree,3 but I
suggest that vascular disease may also cause a difference. One study
found an increased prevalence of differences in patients with coronary
heart disease or peripheral vascular disease,4 and another showed that
83% of vascular surgical patients with differences had angiographic
evidence of innominate or subclavian artery stenosis on the side of
the lower pressure.5
The importance of a difference is already recognised between the arm
and the leg, as measured by the ankle-brachial pressure index, which
is reduced in the presence of asymptomatic peripheral vascular
disease; a reduced index is associated with increased mortality. Why
should the pathology, and prognostic implications, not be the same
with differences between arms?
Until more work is done, hypertensive patients with a reproducible
difference in blood pressure between arms should be investigated and
managed intensively, on the assumption that they have asymptomatic
peripheral vascular disease.?
The article cited above is a comment on a peer-reviewed paper, also in
the British Medical Journal:
Finlay A McAlister and Sharon E Straus. Evidence based treatment of
hypertension: Measurement of blood presssure: an evidence based
review. BMJ 2001 322: 908-911.
http://bmj.bmjjournals.com/cgi/content/full/322/7291/908
Another journal article, aimed at primary care doctors, addresses the
incidence and significance of the so-called ?differential blood
pressure sign:?
Clark CE, Powell RJ. The differential blood pressure sign in general
practice: prevalence and prognostic value. Fam Pract. 2002
Oct;19(5):439-41.
Here?s a link to the full text of the article:
http://fampra.oupjournals.org/cgi/content/full/19/5/439
or to the PDF version, if you prefer:
http://fampra.oupjournals.org/cgi/reprint/19/5/439
The bottom line of this article is that a discrepancy in brachial
(arm) blood pressure greater than 20 mmHg should be investigated
further and is associated with a higher risk of coronary artery
disease and peripheral vascular disease. From the history, coronary
artery disease is present, however, after bypass, such differences
should likely resolve and usually aren?t as large as you describe.
Peripheral vascular disease (also known as peripheral arterial
occlusive disease) is more common in patients with diabetes and,
generally speaking, a disease, like atherosclerosis in the heart, of
the peripheral arteries, for example in the legs or arms. This can
indicate that you have plaques in the arteries of one arm causing a
decrease in blood pressure. It would also suggest that your actual
systemic systolic blood pressure is in the 200 mmHg range. Both of
these situations would require prompt further evaluation since
peripheral vascular disease can lead to loss of a limb and systemic
systolic blood pressure in the 200 mmHg range can lead to strokes.
If you are interested, here is an article from e-medicine with more
information on the topic:
http://www.emedicine.com/med/topic391.htm
The other possibility to explain the discrepancy, alluded to above, is
that there is some innominate (aka brachiocephalic) or subclavian
artery stenosis on the side of the lower pressure. This again
suggests that your true systemic systolic blood pressure is in the 200
mmHg range, which is very concerning. Here is a pictures of the
anatomy of the upper trunk vasculature:
http://nba.uth.tmc.edu/courses/gross2004/lectures/block_1/rogers/thorax_4/images/netter_233a.jpg
http://www.vh.org/adult/provider/anatomy/atlasofanatomy/plate19/01pericardium.html
Proximal subclavian artery stenosis is concerning for the possible
development of a disorder known as subclavian steal. This is a
problem where a partial occlusion of the subclavian artery prior to
the origin of the vertebral artery causes a reversal of the direction
of blood flow in the vertebral artery, which is one of the vessels
supplying the brain. This can lean to neurological symptoms. The
disorder is 3-4 times more likely to occur on the left compared to the
right. Here are two articles describing this phenomenon in detail:
http://www.emedicine.com/med/topic2771.htm
http://www.emedicine.com/radio/topic663.htm
The best diagnostic tool is color Doppler ultrasound, which can assess
the direction of blood flow in the vessels involved.
I hope this information was useful. Again, I would recommend prompt
evaluation by a medical professional, since some serious medical
problems can cause the symptoms you describe.
Best,
-welte-ga |
