Pulse Pressure: Definition and Cardiovascular Significance
Pulse pressure is the difference between systolic and diastolic blood pressure, reflecting left ventricular ejection and aortic elasticity, and serves as an important cardiovascular risk marker particularly in elderly patients with systolic hypertension. 1
Definition and Measurement
Pulse pressure is calculated by subtracting the diastolic blood pressure from the systolic blood pressure:
- Pulse Pressure = Systolic BP - Diastolic BP
- Normal pulse pressure in adults is generally considered to be around 40 mmHg
While easily measured in clinical practice, pulse pressure is a derived measure that combines the imperfections of the original systolic and diastolic measurements 2. Central pulse pressure (measured at the aorta) may provide a more precise assessment than peripheral pulse pressure (measured at the brachial artery) because it accounts for the "amplification phenomena" between peripheral arteries and the aorta 1.
Physiological Basis
Pulse pressure reflects two key physiological factors:
- Left ventricular ejection force
- Arterial elasticity/stiffness
As arteries stiffen with age or disease, their ability to distend during systole decreases, leading to:
- Higher systolic blood pressure
- Lower diastolic blood pressure
- Widened pulse pressure
Clinical Significance
Age-Related Differences
The clinical significance of pulse pressure varies by age:
- In younger individuals (<55 years): Systolic and diastolic pressures are more important predictors of cardiovascular risk 1, 2
- In middle-aged and elderly patients: Pulse pressure shows strong predictive value for cardiovascular events, particularly in those with hypertension and other risk factors 1, 2
Cardiovascular Risk Marker
Elevated pulse pressure is associated with:
- Increased all-cause mortality in non-diabetic hemodialysis patients 1
- Higher risk of cardiovascular events, particularly coronary disease 2, 3
- Arterial stiffness, which increases left ventricular afterload and decreases coronary perfusion 1
In a study of 1,243 chronic hemodialysis patients followed for 9 years, mortality rates increased progressively with pulse pressure:
- PP <59 mmHg: 28% mortality
- PP 60-79 mmHg: 38% mortality
- PP 80-99 mmHg: 46% mortality
- PP ≥100 mmHg: 60% mortality 1
Each 10 mmHg increase in pulse pressure was associated with an 8% increase in relative risk for all-cause mortality in non-diabetic patients 1.
Indicator of Arterial Stiffness
High pulse pressure, particularly in elderly patients with systolic hypertension, indicates increased large artery stiffness and advanced organ damage 1, 2. It serves as an attractive surrogate for pulse wave velocity (PWV), which is a more direct but less easily measured indicator of arterial stiffness 1.
Clinical Applications
Risk Assessment
While classification and risk assessment should continue to be based primarily on systolic and diastolic blood pressures, pulse pressure should be considered when identifying elderly patients with systolic hypertension who are at particularly high risk 1, 2.
Values such as 50 or 55 mmHg have been suggested as potential thresholds for abnormality in older adults, though no definitive cutoff values have been established 1, 2.
Treatment Considerations
When treating hypertension in patients with wide pulse pressure:
- Excessive diastolic blood pressure reduction may compromise coronary perfusion, especially in elderly patients or those with coronary artery disease 2
- Medications that preferentially reduce arterial stiffness may be beneficial in reducing pulse pressure 2
- Treating hypertension can reduce pulse wave velocity, which may lead to better survival rates 1
Potential Pitfalls in Interpretation
- Pulse pressure can vary in the same individual and has no fixed relation to absolute blood pressure levels 2
- Normal pulse pressure increases with age due to natural arterial stiffening 2
- Certain conditions can cause widened pulse pressure independent of age-related arterial stiffness, including aortic regurgitation, hyperthyroidism, and high-output heart failure states 2
In conclusion, pulse pressure is an important cardiovascular parameter that provides valuable information about arterial stiffness and cardiovascular risk, particularly in older adults. While systolic and diastolic blood pressures remain the primary measurements for classifying hypertension, pulse pressure offers complementary information that can enhance risk stratification and potentially guide treatment decisions.