Radial Pulse: Significance and Features | Heart Rate | Humans | Biology

In this article we will discuss about:- 1. Features of Radial Pulse 2. Recording of Radial Pulse 3. Significance 4. Varieties.

Features of Radial Pulse:

While examining pulse the following features are to be noted:

i. Rate means the frequency of pulse per minute. Normally, it corresponds to heart rate. Increased pulse rate is called tachycardia and diminished pulse rate is called bradycardia.

ii. Rhythm indicates whether the beats are equidistant or not

iii. Volume means the rise of the pulse wave above the diastolic level. Other factors remaining constant it varies as the stroke volume.

iv. Tension is the approximate measure of the systolic pressure. It is determined by noting the amount of pressure required to obliterate the pulse wave. It is examined with three fingers placed side by side on the radial artery.

The proximal finger adjusts the pressure; the middle finger remains stationary and only feels the appearance and disappearance of the pulse wave; while the distal finger applies a constant maximum pressure to stop retrograde pulsation.

Recording of Radial Pulse:

For clinical purposes, the commonest instru­ment used, is Dudgeon’s Sphygmograph. For more accurate work, elaborate apparatus for optical recording is used. The record of radi­al pulse is shown in Fig. 7.96.

The upstroke is abrupt and without any secondary wave on it. Near the middle of the down-stroke there is a sharp depression called the dicrotic notch. This is immediately followed by a small wave, the dicrotic wave. These two features are constant­ly present in a normal pulse tracing. The wave from the beginning of the tracing up to the di­crotic notch is called the primary wave or per­cussion wave.

This whole wave corresponds to ventricular systole. The rise and fall of pressure in this wave follow the similar pressure changes in the aorta and ventricles. The dicrotic notch is due to the sharp fall of pressure caused by the rolling back of aortic blood towards the left ventricle at the beginning of diastole. The dicrotic wave is caused by the return of the same blood column being reflected back by the closed semilunar valves.

Sometimes secondary oscillations are found on the down-stroke both above and below the dicrotic wave, being known as the predicrotic wave and postdicrotic wave respectively. These are due to elastic os­cillations of the aorta.

The normal pulse is called catacrotic pulse. When a secondary wave is found on the up­stroke the wave is called anacrotic wave and the pulse is called anacrotic pulse. When the dicrotic wave becomes so prominent that it can be easily felt with the fingers the pulse is known as dicrotic pulse.

Significance of Radial Pulse:

A large primary wave is generally due to:

i. A large stroke volume.

ii. Slow heart rate.

iii. Low peripheral resistance.

A small primary wave is due to:

i. Small output.

ii. Rapid heart rate.

iii. High peripheral resistance (i.e., high blood pressure).

iv. Stiffness of the vessel walls.

The down-stroke becomes more abrupt in subjects with low diastolic pressure. It becomes more sloping in cases with high blood pressure.

Special Varieties of Pulse:

Depending on the variations of the above features, various types of pulse waves are clinically described.

The following types are of special interest:

i. Sinus Arrhythmia:

The frequency of the pulse increases during inspiration and falls during expiration. Sometimes it is found in children. It is due to alteration of the vagal tone during respiration.

ii. Water-Hammer Pulse:

The rise and fall are steep and abrupt without any dicrotic notch or wave. This is typically found in aortic incompetence.

iii. Pulsus Alternans:

Here, the pulse is alternately large and small. It is found in serious myocardial damage.

iv. Pulsus Paradoxes:

The volume and frequency is more during expiration than during inspiration, i.e., reverse of sinus arrhythmia.

v. Weak Pulse:

A weak pulse at the radial artery generally indicates that the quantity of blood ejected by the left ventricle to the arteries with each beat is less than normal. From the above discussion, it will be noted that examination of pulse is of great clinical importance. From it, the condition of the heart, of the arteries, the extent of blood pressure, etc., may be known.