1. How does AR affect the blood pressure in the legs in comparison with that in the arms? What is this sign of AR called?
ANS: AR exaggerates the tendency for the leg systolic pressure to be higher than that in the arms. If the difference is greater than normal, i.e., more than 20 mmHg, it is known as a positive Hill's sign .
Note: It is easy to remember because blood pressure increases, i.e., goes "uphill" in AR as the examiner goes down the body.
2. Why is the cuff systolic pressure in AR higher in the legs than in the arms?
ANS: One theory is that reflected waves from the periphery sum with forward waves. These summed waves are known as standing waves.
3. How can Hill's sign be used to grade the severity of AR?
ANS: In mild AR the difference is up to 20 mmHg (i.e., the difference is in the normal range). In moderate AR the difference is 20-40 mmHg; in severe AR the difference is over 60 mmHg. A difference of between 40 and 60 mmHg may represent either moderate or severe AR .
4. What produces a falsely low Hill's sign (i.e., less difference than would be expected from the severity of the AR)?
ANS: a. Congestive heart failure, presumably because of the poor stroke volume. A positive Hill's sign may depend, at least in part, on a strong myocardial contraction. b. Significant AS.
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