Page 59 - Clinical Pearls in Cardiology

Arterial Pulse and Blood Pressure 47

the relative rapid flow in the aortic arch may cause a
Venturi effect of relative suction on these
cephalobrachial vessels. This may tend to reduce the
net effect of peripheral amplification of blood
pressures caused by reflection.
A cuff of greater width (about 18 cms) is used for
measuring blood pressure in the leg. The patient lies in
the prone position and the cuff is wrapped around the
thigh. Auscultation for the Koratkoff’s sounds is carried
out over the popliteal artery, in the popliteal fossa.
26. What is meant by isolated systolic hypertension (ISH)?
Systolic blood pressure rises almost linearly between
30 and 84 years of age, whereas diastolic pressure rises
until 50 years of age and then levels off or decreases.
The most common type of hypertension seen in older
persons is the isolated systolic hypertension or ISH. It
is defined as systolic blood pressure of 140 mm Hg or
more and diastolic blood pressure of less than 90 mm Hg.
With aging, the elastin fibers in the walls of the
arteries are gradually replaced by collagen fibers that
render the vessels stiffer and less compliant. Stiffened
arteries cause an increase in the rate of return of reflected
arterial pressure waves from the periphery, thereby
raising the systolic pressure. Also, because of increased
wall stiffness, the aorta and large arteries are unable to
buffer the rise in systolic pressure that occurs as blood
is ejected from the left ventricle, and they are less able
to store the energy needed to maintain the diastolic
pressure. All these factors result in elevated systolic
pressure and diminished diastolic pressure. Low dose
thiazide diuretic is the preferred initial treatment for ISH.
Isolated systolic hypertension is also seen in high output
states like thyrotoxicosis, anemia, etc.