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Pulse pressure: what ageing reveals about our arteries Why does systolic blood pressure tend to rise with age while diastolic pressure may actually fall? The answer lies not simply in the heart, but in the progressive loss of elasticity of our arteries. Let's decipher it! Pulse pressure (PP) is the difference between systolic and diastolic blood pressure. That simple. For a blood pressure of 120/80 mmHg, PP is 40 mmHg. But what does this difference actually tell us? Each heartbeat ejects blood into the aorta, stretching its elastic walls. During diastole, the aorta recoils, maintaining blood flow even when the heart is relaxing. This is the Windkessel effect, which transforms intermittent cardiac ejection into relatively continuous peripheral blood flow. PP therefore depends primarily on two factors: - stroke volume and - arterial compliance. Greater stroke volume tends to increase PP, whereas greater arterial elasticity reduces it. What changes with age? As arteries age, elastin becomes fragmented, collagen contributes increasingly to wall stiffness, and advanced glycation end-products promote collagen cross-linking. The physiological consequences are particularly interesting. - Systolic pressure rises: a stiffer aorta expands less during ventricular ejection, producing a greater pressure increase. - Diastolic pressure may fall: reduced elastic recoil compromises the pressure maintained between heartbeats. - Pulse pressure widens: the difference between systolic and diastolic pressures increases. Furthermore, increased arterial stiffness accelerates pulse-wave propagation. Reflected pressure waves return earlier, often during systole rather than diastole, augmenting central systolic pressure. Why does this matter clinically? A widened pulse pressure increases left ventricular pulsatile afterload and is associated with cardiovascular risk, particularly in older adults. Meanwhile, reduced diastolic pressure may compromise coronary perfusion, especially in patients with coronary artery disease, because much of left ventricular myocardial perfusion occurs during diastole. Blood pressure is therefore more than two numbers: the distance between them reveals how effectively our arteries store and release the energy of each heartbeat.