Page 58 - Clinical Pearls in Cardiology

46 Clinical Pearls in Cardiology

patient’s upper arm. It should also be long enough to
tightly encircle the whole arm. The central part of the
inflatable bladder within the cuff should be positioned
over the brachial artery while wrapping the cuff around
the arm. The cuff encircling the arm should be at the
level of the patient’s heart as shown in Fig. 9. At the
initial visit, blood pressure should be measured in both
the arms, first by the palpatory method, and then by the
auscultatory method (Fig. 9). The arm with the higher
blood pressure should be used for taking subsequent
blood pressure recordings. At least two readings that are
5 minutes apart should be taken.
25. Why is blood pressure in the leg higher than that in
the arm?
The blood pressure differential between the arm and the
leg is probably multifactorial in origin. The postulated
factors are the following:
• The reflecting sites that reflect back the incident or
forward going pressure pulse waves are probably
more in the lower extremities than in the arm. Hence
the resultant pressure wave that is produced by the
summation of the incident and the reflected waves is
very large. This results in greater blood pressure in
the lower extremities.
• The vessels of the lower extremities are probably
more muscular.
• The age-related change in the compliance of arteries
is more in the lower limb vessels than in the upper
limb vessels.
• The upper arm vessels tend to arise anatomically at
approximately 90° angle from the aortic arch. The
diameter of these vessels being smaller than the aorta,