What is the definition of pulse?

Definition of Pulse

Pulse is the palpable rhythmic expansion and contraction of an artery produced by the pressure wave generated by ventricular ejection during each cardiac cycle, assessed at various anatomical sites including the brachial, radial, ulnar, femoral, popliteal, dorsalis pedis, and posterior tibial arteries. 1

Clinical Assessment Components

The pulse examination encompasses several key characteristics that should be systematically evaluated:

Pulse Intensity Grading

• Pulse intensity should be assessed numerically using a standardized 0-3 scale: 0 = absent, 1 = diminished, 2 = normal, 3 = bounding 1
• This standardized grading system allows for consistent documentation and communication between healthcare providers across different clinical settings 1

Anatomical Sites for Palpation

• Pulses should be palpated at multiple standardized locations: brachial, radial, ulnar, femoral, popliteal, dorsalis pedis, and posterior tibial sites 1
• Systematic examination of all pulse sites is essential because the pulse examination has well-defined limitations in sensitivity, specificity, and predictive value that must be supplemented by objective vascular testing 1

Relationship to Heart Rate

• Heart rate represents the number of heartbeats per unit of time, usually expressed as beats per minute, which directly corresponds to the pulse rate in normal circumstances 1
• The pulse rate typically equals heart rate when cardiac rhythm is regular and each ventricular contraction produces adequate stroke volume to generate a palpable peripheral pulse 1

Pulse Deficit

• Pulse deficit is defined as the difference between the apical heart rate and the peripheral pulse rate, which signals an arrhythmia when present 2
• This deficit occurs when some cardiac contractions fail to generate sufficient stroke volume to produce a palpable peripheral pulse, commonly seen in atrial fibrillation or frequent premature beats 2
• Monitoring for pulse deficit is essential when a patient's pulse rhythm is irregular 2

Pulse Pressure

• Pulse pressure is calculated as systolic blood pressure minus diastolic blood pressure, representing the pulsatile component of blood pressure 1
• A wide pulse pressure (typically >60 mmHg in elderly patients) serves as a marker of increased large artery stiffness and advanced vascular damage 1
• In elderly patients with isolated systolic hypertension, a high pulse pressure combined with low diastolic pressure (60-70 mmHg) indicates particularly high cardiovascular risk 1

Clinical Significance of Pulse Pressure

• Wide pulse pressure is an independent predictor of cardiovascular mortality, particularly coronary mortality, in middle-aged and elderly populations 3
• The predictive value of pulse pressure varies with clinical characteristics—it shows strong predictive value in hypertensive patients with cardiovascular risk factors but less so in younger individuals without established disease 1

Pathological Pulse Characteristics

Thready (Filiforme) Pulse

• A thready pulse is characterized by weak, low amplitude pulsations that are difficult to palpate, resembling a fine thread under the examiner's fingers, indicating significant reduction in stroke volume and hemodynamic deterioration 4
• This finding signals hemodynamic compromise and reduced stroke volume, frequently associated with shock states or significant cardiovascular compromise 4
• Common causes include cardiac tamponade (fluid accumulation limiting ventricular filling), constrictive pericarditis (rigid pericardium restricting filling), and severe ventricular dysfunction in advanced heart failure 4
• The presence of a thready pulse indicates significant hemodynamic compromise requiring urgent intervention, and its persistence despite treatment suggests an unfavorable prognosis 4

Important Clinical Caveats

• The pulse waveform derived from peripheral pulse monitors or pulse oximeters represents blood volume change in tissue (perfusion/blood flow) rather than arterial pressure itself 5
• Heart rate is an important confounder of pulse wave velocity assessment—standardizing measurements for heart rate level is mandatory when interpreting changes in arterial stiffness parameters 6
• Pulse examination must be supplemented with objective vascular testing due to inherent limitations in sensitivity and specificity 1