脈壓 Pulse pressure

http://en.wikipedia.org/wiki/Pulse_pressure

Consistently high values

If the usual resting pulse pressure is consistently greater than 40 mmHg, e.g. 60 or 80 mmHg, the most likely basis is stiffness of the major arteries, aortic regurgitation (a leak in the aortic valve), arteriovenous malformation (an extra path for blood to travel from a high pressure artery to a low pressure vein without the gradient of a capillary bed), hyperthyroidism or some combination. (A chronically increased stroke volume is also a technical possibility, but very rare in practice.) While some drugs for hypertension have the side effect of increasing resting pulse pressure irreversibly, other hypertension drugs, such as ACE Inhibitors, have been shown to lower pulse pressure. A high resting pulse pressure is harmful and tends to accelerate the normal aging of body organs, particularly the heart, the brain and kidneys. A high pulse pressure combined with bradycardia is associated with increased intracranial pressure and should be reported to a physician immediately.

Relationship to heart disease

Recent work suggests that a high pulse pressure is an important risk factor for heart disease. A meta-analysis in 2000, which combined the results of several studies of 8,000 elderly patients in all, found that a 10 mm Hg increase in pulse pressure increased the risk of major cardiovascular complications and mortality by nearly 20%.^[5] Heightened pulse pressure is also a risk factor for the development of atrial fibrillation.^[6] The authors of the meta-analysis suggest that this helps to explain the apparent increase in risk sometimes associated with low diastolic pressure, and warn that some medications for high blood pressure may actually increase the pulse pressure and the risk of heart disease.

Self measurement

Pulse pressure readings can be taken on a home monitoring blood pressure device. Most home monitoring blood pressure devices display systolic and diastolic blood pressure and pulse pressure readings. Monitoring at home will measure true pulse and blood pressure and provide a doctor with a log of readings over time.

Treatment

If the patient suffers from elevated pulse pressure, treatment should include medication that addresses this factor, such as an angiotensin-converting enzyme inhibitor (ACE inhibitor).^[7]

Effect of folic acid

A 2005 study found that 5 mg. of folate daily over a three-week period reduced pulse pressure by 4.7 mg. Hg. compared with a placebo, and concluded that^[8]

Folic acid is a safe and effective supplement that targets large artery stiffness and may prevent isolated systolic hypertension.