Webster's New World Medical Dictionary

43
Bernard-Soulier syndrome
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Bernstein test
A test to find out if heartburn is
caused by acid in the esophagus, and so to diagnose
GERD (gastroesophageal reflux disease). The test
involves dripping a mild acid, similar to stomach
acid, through a tube placed in the esophagus. Also
known as esophageal acid infusion test.
berry aneurysm
See 
aneurysm, berry.
beta blocker
A class of drugs that block the
effect of beta-adrenergic substances such as adren-
aline (epinephrine), that play a key role in the sym-
pathetic portion of the involuntary nervous system.
By blocking the action of the sympathetic nervous
system on the heart, they slow the heartbeat and
relieve stress on the heart. Beta blockers are used to
treat abnormal heart rhythms, specifically to prevent
abnormally fast heart rates (tachycardias) or irreg-
ular heart rhythms, such as premature ventricular
beats. Because beta blockers reduce the demand of
the heart muscle for oxygen, they can be useful in
treating angina. They have also become important
drugs in improving survival after a heart attack. Due
to their effect on blood vessels, beta blockers can
lower the blood pressure and are of value in the
treatment of hypertension. Other uses include the
prevention of migraine headaches and the treatment
of familial or hereditary essential tremors. Beta
blockers reduce pressure within the eye and they
are therefore used to lessen the risk of damage to
the optic nerve and loss of vision in patients with
glaucoma. Beta blockers include acebutolol (brand
name: Sectral), atenolol (brand name: Tenormin),
bisoprolol (brand name: Zebeta), metoprol (brand
names: Lopressor, Lopressor LA, Toprol XL),
nadolol (brand name: Corgard), and timolol
(brand name: Blocadren). Topical beta blockers for
the eye include timolol ophthalmic solution (brand
name: Timoptic) and betaxolol hydrochloride
(brand name: Betoptic).