A pulse is felt by compressing an artery against a bone. The first pulse to be examined is the right radial pulse. The timings of the left radial and femoral pulses are then compared with that of the right radial pulse. Delayed femoral pulsation occurs because of a proximal stenosis, particularly of the aorta (coarctation).

Pulse rate

The pulse rate should be between 60 and 80 beats per minute (b.p.m.) when an adult patient is lying quietly in bed. Young children may have higher pulse rates, and athletes and elderly adults may have slower rates. The exact rate is often less valuable than the changes in heart rate observed over time (seen on a pulse chart). When the pulse is irregular, not all ventricular systolic beats may be detected by palpation of the radial pulse. Such apex-radial pulse deficits may be appreciated by counting the radial pulse whilst simultaneously listening to the heartbeat with a stethoscope, and are commonly associated with atrial fibrillation and ventricular ectopy.

Rhythm

In normal subjects the pulse is regular except for a slight quickening in early inspiration and a slowing in expiration (sinus arrhythmia). Irregularities of the pulse rhythm are usually due to premature beats, intermittent heart block or atrial fibrillation.

Premature beats occur as occasional or repeated irregularities superimposed on a regular pulse rhythm. Similarly, intermittent heart block is revealed by occasional beats dropped from an otherwise regular rhythm. A more irregular pattern (irregularly irregular) of heartbeats in which no pattern is recognizable occurs in atrial fibrillation. This irregular pattern persists when the pulse quickens in response to exercise, in contrast to pulse irregularity due to ectopic beats, which usually disappears on exercise. However, this is not a reliable way to distinguish ectopic beats from other causes of pulse irregularity.

Carotid pulse

Carotid pulsations are not normally apparent on inspection of the neck but may be visible (Corrigan's sign) in conditions associated with a large-volume pulse, including high output states (such as thyrotoxicosis, anaemia or fever) and in aortic regurgitation. The carotid pulse may also be visible when the carotid artery is aneurysmal or kinked. The amplitude and shape of the carotid pulse is normally examined by palpation of the right carotid artery. Light palpation should be used to detect the presence of a thrill.

A large-volume pulse may also be associated with the large stroke volume that is necessary if bradycardia is present. A 'collapsing' or 'water hammer' pulse is a large-volume pulse characterized by a short duration with a brisk rise and fall. This is best appreciated by palpating the radial artery with the palmer aspect of four fingers whilst elevating the patient's arm above the level of the heart. A collapsing pulse is characteristic of aortic valvular regurgitation or a persistent ductus arteriosus.

A small-volume pulse is seen in cardiac failure, shock and obstructive valvular or vascular disease. It may also be present during tachyarrhythmias. The pulse of aortic stenosis is not only small in volume but is slow in rising to a peak (plateau pulse) and is often associated with a notch on the upstroke (anacrotic pulse) or a systolic shudder or thrill.

Paradoxical pulse

Paradoxical pulse is a misnomer, as it is actually an exaggeration of the normal pattern. In normal subjects, the systolic pressure and the pulse pressure (the difference between the systolic and diastolic blood pressures) fall during inspiration. The normal fall of systolic pressure is less than 10 mmHg, and this can be measured using a sphygmomanometer. It is due to increased pulmonary intravascular volume during inspiration. In severe airflow limitation (especially severe asthma) there is an increased negative intrathoracic pressure on inspiration which enhances the normal fall in blood pressure. In patients with cardiac tamponade, the fluid in the pericardium increases the intrapericardial pressure, thereby impeding diastolic filling of the heart. The normal inspiratory increase in venous return to the right ventricle is at the expense of the left ventricle, as both ventricles are confined by the accumulated pericardial fluid within the pericardial space. Paradox can occur through a similar mechanism in constrictive pericarditis but is less common.

Alternating pulse (pulsus alternans)

This is characterized by regular alternate beats that are weak and strong. It is a feature of severe myocardial failure and is due to the prolonged recovery time of damaged myocardium; it indicates a very poor prognosis. It is easily noticed when taking the blood pressure because the systolic pressure may vary from beat to beat by as much as 50 mmHg. Pulsus alternans may also occur when there is rapid, abnormal tachycardia. In this case it acts as a compensatory mechanism and does not indicate a poor prognosis. Pulsus alternans should be distinguished from a bigeminal pulse (see below).

Bigeminal pulse (pulsus bigeminus)

This is due to a premature ectopic beat following every sinus beat. The rhythm is not regular because every weak pulse is premature.

Pulsus bisferiens

This is a pulse that is found in hypertrophic obstructive cardiomyopathy and in mixed aortic valve disease (regurgitation combined with stenosis). The first systolic wave is the 'percussion' wave produced by the transmission of the left ventricular pressure in early systole. The second peak is the 'tidal' wave caused by recoil of the vascular bed. This normally happens in diastole (the dicrotic wave), but when the left ventricle empties slowly or is obstructed from emptying completely, the tidal wave occurs in late systole. The result is a palpable double pulse.