How does pulse rate in cardiovascular disease differ from a normal pulse rate?

Normal Pulse Rate vs Pulse Rate in Cardiovascular Disease

Patients with cardiovascular disease typically have abnormal heart rate responses compared to healthy individuals, including elevated resting heart rates, reduced heart rate reserve, and altered heart rate responses during exercise, which are associated with increased cardiovascular mortality and morbidity.

Normal Heart Rate Parameters

• Normal resting heart rate typically ranges from 60-75 beats per minute in healthy adults 1
• The normal heart rate response during exercise is characterized by an initial decrease in parasympathetic activity (vagal withdrawal) followed by increased sympathetic activity 1
• In healthy individuals, heart rate increases linearly with oxygen consumption (VO₂) during exercise, with the slope reflecting stroke volume (higher stroke volume = lower heart rate) 1
• Normal individuals typically achieve their age-predicted maximum heart rate during maximal exercise, with little or no heart rate reserve (HRR) remaining 1
• Age-predicted maximum heart rate can be calculated using formulas such as 220 - age or 210 - (age × 0.65), with the latter being more accurate for older adults 1

Heart Rate Abnormalities in Cardiovascular Disease

Resting Heart Rate

• Elevated resting heart rate is an independent risk factor for cardiovascular disease and mortality in both men and women 1, 2
• For each 15 beats/min increase in resting heart rate, the hazard ratio for cardiovascular mortality increases by 24% in men and 32% in women 2
• The relationship between elevated heart rate and cardiovascular mortality is strong, graded, and independent of other factors including blood pressure and physical activity 1
• This relationship has been demonstrated in various populations including the general population, hypertensives, diabetics, and those with pre-existing coronary artery disease 1

Heart Rate During Exercise

• Patients with cardiovascular disease often show impaired heart rate responses during exercise 1
• In heart failure patients, heart rate responses become increasingly abnormal as disease severity increases 1
• Abnormal heart rate recovery after exercise is an independent predictor of mortality 1
• A low peak VO₂ with normal peak heart rate may indicate early/mild heart disease, mitral valve disease, pulmonary vascular disease, or coronary artery disease 1
• Patients with cardiovascular disease often have a steeper HR-VO₂ relationship (higher heart rate for a given oxygen consumption) 1

Oxygen Pulse

• Oxygen pulse (VO₂/HR) reflects the amount of oxygen extracted per heartbeat and is often reduced in cardiovascular disease 1
• In cardiovascular disease, a low or flat oxygen pulse with increasing work rate may indicate reduced stroke volume and/or failure of skeletal muscle oxygen extraction 1
• The normal oxygen pulse increases with incremental exercise due to increases in both stroke volume and oxygen extraction 1

Specific Cardiovascular Conditions and Heart Rate Patterns

Heart Failure

• Patients with heart failure show greater heart rate reserve (HRR) as disease severity increases 1
• Impaired heart rate responses are frequently observed in moderate to severe heart failure 1
• An abnormal VE/VCO₂ slope (greater than 34) during exercise has been suggested as an independent predictor of mortality in heart failure patients 1

Pulmonary Vascular Disease

• Pulmonary vascular disease is associated with abnormal VE/VCO₂, VD/VT, PaO₂, and P(A-a)O₂ responses in addition to heart rate abnormalities 1
• These patients often show a low peak VO₂ with normal peak heart rate pattern 1

Coronary Artery Disease

• Patients with coronary artery disease may have chronotropic incompetence (inability to increase heart rate appropriately during exercise) 1
• If predicted peak heart rate is not achieved and the VO₂ is low, cardiac limitation due to coronary artery disease may be present 1

Hypertension and Arterial Stiffness

• Increased arterial stiffness in cardiovascular disease leads to increased pulse pressure (difference between systolic and diastolic blood pressure) 1
• Pulse pressure >60 mm Hg with systolic blood pressure >135 mm Hg is associated with increased cardiovascular risk 1
• Pulse wave velocity (PWV), a measure of arterial stiffness, is independently associated with carotid atherosclerosis 3
• A 10 mm Hg increase in pulse pressure is associated with a 26% increase in risk of cardiovascular death in persons 25-45 years of age 4

Clinical Implications

• Taking the resting pulse should be part of routine cardiovascular risk assessment 5
• Heart rate should be reported along with other variables during exercise testing protocols 1
• A maximal heart rate that approaches the predicted maximal value suggests achievement of maximal or near maximal patient effort 1
• A reduced maximal heart rate must be interpreted in light of a patient's disease and current medications 1
• For patients with known cardiovascular disease, cardiac rehabilitation programs that include supervised physical exercise can be beneficial 1

Common Pitfalls in Heart Rate Assessment

• Using heart rate as a strict exercise end point is not recommended due to considerable variability (10-15 beats/minute) within age groups 1
• Beta-blockers and other medications can significantly affect heart rate responses and must be considered when interpreting results 1
• The relationship between heart rate and cardiovascular risk may be weaker in females than in males 5
• Heart rate abnormalities must be interpreted in the context of other clinical findings, as similar patterns can occur in different conditions 1