The accomplished clinician is able, while inspecting
the patient’s hands, to palpate the radial artery at the
wrist. Patients expect to have their pulse taken as part
of a proper medical examination. The clinician can
feel the pulse while talking to the patient and while
looking for other signs. When this traditional part ofthe examination is performed with some ceremony, it
may help to establish rapport between patient and
doctor.
Although the radial pulse is distant from the
central arteries, certain useful information may be
gained from examining it. The pulse is usually felt just
medial to the radius, using the forefinger and middle
finger pulps of the examining hand (see Fig. 5.15).
The following observations should be made: (1) rate of
pulse, (2) rhythm and (3) presence or absence of delay
of the femoral pulse compared with the radial pulse
(radiofemoral delay; see Fig. 5.17). The character and
volume of the pulse are better assessed from palpation
of the brachial or carotid
arteries.Rate of pulse
Practised observers can estimate the rate quickly. Formal
counting over 30 seconds is accurate and requires only
simple mathematics to obtain the rate per minute. The
normal resting heart rate in adults is usually said to be
between 60 and 100 beats per minute but a more
sensible range is probably 55 to 95 (95% of normal
people). Bradycardia (from the Greek bradys ‘slow’,
kardia ‘heart’) is defined as a heart rate of less than 60
beats per minute. Tachycardia (from the Greek tachys
‘swift’, kardia ‘heart’) is defined as a heart rate over 100
beats per minute (see the OSCE ECGs nos 2, 3 and 4
at ). The causes of bradycardia and
tachycardia are listed in Table 5.1.
Rhythm
The rhythm of the pulse can be regular or irregular. An
irregular rhythm can be completely irregular with no
pattern (irregularly irregular or chaotic rhythm); this is
usually due to atrial fibrillation (see Table 5.1). In atrial
fibrillation coordinated atrial contraction is lost, and
chaotic electrical activity occurs with bombardment of
the atrioventricular node with impulses at a rate of over
600 per minute. Only a variable proportion of these is
conducted to the ventricles because (fortunately) the
AV node is unable to conduct at such high rates. In
this way, the ventricles are protected from very rapid
rates, but beat irregularly, usually at rates between 150
and 180 per minute (unless the patient is being treated
with drugs to slow the heart rate [see the OCSE ECG
no. 8 at ]). The pulse also varies
in amplitude from beat to beat in atrial fibrillation
because of differing diastolic filling times. This type
of pulse can occasionally be simulated by frequent
irregularly occurring supraventricular or ventricular
ectopic beats.
Patients with atrial fibrillation or frequent ectopic
beats may have a detectable pulse deficit. This means
that the heart rate when counted by listening to the
heart with the stethoscope is higher than the rate
obtained when the radial pulse is counted at the wrist.
In these patients the heart sounds will be audible with
every systole, but some early contractions preceded
by short diastolic filling periods will not produce
enough cardiac output for a pulse to be palpable at
the wrist.
An irregular rhythm can also be regularly irregular.
For example, in patients with sinus arrhythmia the
pulse rate increases with each inspiration and decreases
with each expiration (see the OCSE ECG no. 7 at
); this is a normal finding. It is
associated with changes in venous return to the heart.
Patterns of irregularity (see Fig. 5.16) can also occur
when patients have frequent ectopic beats. These may
arise in the atrium (atrial ectopic beats, AEBs) or in the
ventricle (ventricular ectopic beats, VEBs [see the OCSE
ECG no. 6 at ]) Ectopic beats quite
commonly occur in a fixed ratio to normal beats. When
every second beat is an ectopic one, the rhythm is called
bigeminy. A bigeminal rhythm caused by ectopic beats
has a characteristic pattern: normal pulse, weak (or
absent) pulse, delay, normal pulse and so on. Similarly,
every third beat may be ectopic—trigeminy. A pattern
of irregularity is also detectable in the Wenckebacho
phenomenon. Here the AV nodal conduction time
increases progressively until a non-conducted atrial
systole occurs. Following this, the AV conduction time
shortens and the cycle begins again.
Radiofemoral and radial–
radial delay
Radiofemoral delay is an important sign, especially in
a young patient with hypertension. While palpating
the radial pulse, place the fingers of your other hand
over the femoral pulse, which is situated below the
inguinal ligament, one-third of the way up from the
pubic tubercle (see Fig. 5.17). A noticeable delay in
the arrival of the femoral pulse wave suggests the
diagnosis of coarctation of the aorta, where a congenital
narrowing in the aortic isthmus occurs at the level
where the ductus arteriosus joins the descending aorta.
This is just distal to the origin of the subclavian artery.
This lesion can cause upper limb hypertension.
You can palpate both radial pulses together to
detect radial–radial inequality in timing or volume,
which is usually due to a large arterial occlusion by an
atherosclerotic plaque or aneurysm, or to subclavian
artery stenosis on one side. It can also be a sign of
dissection of the thoracic aorta.
o Marel Frederik Wenckebach (1864–1940), a Dutch physician who practised
in Vienna. He worked out the mechanism of this arrhythmia without
having ECGs.Feeling for radiofemoral delay
FIGURE 5.17
Character and volume
Character and volume are poorly assessed by palpating
the radial pulse; the carotid or brachial arteries should
be used to determine the character and volume of the
pulse, as these more accurately reflect the form of the
aortic pressure wave. However, the collapsing (bounding)
pulse of aortic regurgitation, and pulsus alternans
(alternating strong and weak pulse) of advanced left
ventricular failure, may be readily apparent in the radial
pulse.
Condition of the vessel wall
Only changes in the medial layer of the radial artery
can be assessed by palpation. Thickening or tortuosity
will be detected commonly in the arteries of elderly
people. These changes, however, do not indicate the
presence of luminal narrowing due to atherosclerosis.
Therefore, this sign is of little clinical value.
BLOOD PRESSURE
Measurement of the arterial blood pressurep is an
essential part of the examination of almost any
patient. (See the OCSE video Taking the blood
pressure and examining the hypertensive patient at
.) Usually, indirect measurements
p Blood pressure was first measured in a horse in 1708 by Stephen Hales,
an English clergyman. Measurement of the blood pressure was the last of
the traditional vital signs measurements to come into regular use. It was
not until early in the 20th century that work by Korotkoff and Janeway
led to its routine use.