Pulse pressure

Jump to: navigation, search

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Pulse pressure is the change in blood pressure seen during a contraction of the heart (the difference between diastolic and systolic blood pressure). The normal pulse pressure is 30-40 mmHg. A pressure that exceeds this is called a wide pulse pressure. A pressure that is smaller than this (<25 mmHg) is a narrow pulse pressure.

Calculation

Formally it is the systolic pressure minus the diastolic pressure.[1]

Theoretically, the pulse pressure can be conceptualized as stroke volume X compliance. For instance, even though the right and left ventricles have similar stroke volumes, because the aorta is the most compliant vessel (due to the large amount of elastic fibers) the aortic pulse pressure is much greater than the pulmonary pulse pressure.

Values and variation

Usually, the resting pulse pressure in healthy adults, sitting position, is about 40 mmHg. The pulse pressure increases with exercise due to increased stroke volume, healthy values being up to pulse pressures of about 100 mmHg, simultaneously as total peripheral resistance drops during exercise. In healthy individuals the pulse pressure will typically return to normal within about 10 minutes.

For most individuals, during exercise, the systolic pressure progressively increases while the diastolic remains about the same. In some very aerobically athletic individuals, the diastolic will progressively fall as the systolic increases. This behavior facilitates a much greater increase in stroke volume and cardiac output at a lower mean arterial pressure and enables much greater aerobic capacity and physical performance. The diastolic drop reflects a much greater fall in total peripheral resistance of the muscle arterioles in response to the exercise (a greater proportion of red versus white muscle tissue).

Low values

If the usual resting pulse pressure is measured as less than 40 mmHg, the most common reason is an error of measurement. If the pulse pressure is genuinely low, e.g. 25 mmHg or less, the cause may be low stroke volume, as in Congestive Heart Failure and/or shock, a serious issue. This interpretation is reinforced if the resting heart rate is relatively rapid, e.g. 100-120 (in sinus tachycardia), reflecting increased sympathetic nervous system activity and the body's response to low stroke volume and low cardiac output.

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.) Some drugs for hypertension have the side effect of increasing resting pulse pressure irreversibly. A high resting pulse pressure is harmful and tends to accelerate the normal ageing 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%.[2] The authors 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.

Wide pulse pressure causes

Overview

Wide pulse pressure can result from a variety of causes, with anemia being the most common.

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Wide pulse pressure in itself is not a life threatening condition.

Common Causes

The most common cause of wide pulse pressure is anemia, other causes include:

Causes by Organ System

Cardiovascular Aortic coarctation, anemia, aortic regurgitation, arteriosclerosis of the aorta, arteriosclerosis of renal arteries, arteriovenous fistula, Beriberi heart disease, isolated systolic hypertension
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug and Toxin Side Effect No underlying causes
Ear Nose Throat No underlying causes
Endocrine Hyperthyroidism
Environmental No underlying causes
Gastroenterologic No underlying causes
Genetic [No underlying causes
Hematologic Anemia
Iatrogenic No underlying cause
Infectious Disease No underlying causes
Musculoskeletal / Ortho No underlying causes
Neurologic No underlying cause
Nutritional / Metabolic No underlying cause
Obstetric/Gynecologic Pregnancy
Oncologic No underlying causes
Opthalmologic No underlying causes
Overdose / Toxicity [No underlying causes
Psychiatric No underlying causes
Pulmonary No underlying causes
Renal / Electrolyte Arteriosclerosis of renal arteries
Rheum / Immune / Allergy No underlying causes
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous No underlying causes

Causes in Alphabetical Order

Narrowed Pulse Pressure causes

Overview

Narrowed Pulse Pressure can be result from a variety of causes, with congestive heart failure being the most common.

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Narrowed Pulse Pressure in itself is not a life threatening condition.

Common Causes

Causes by Organ System

Cardiovascular Congestive heart failure, constructive pericarditis, pericardial effusion, severe aortic stenosis, shock, tachycardia |-
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug and Toxin Side Effect No underlying causes
Ear Nose Throat No underlying causes
Endocrine No underlying causes
Environmental No underlying causes
Gastroenterologic Ascites
Genetic [No underlying causes
Hematologic No underlying causes
Iatrogenic No underlying cause
Infectious Disease No underlying causes
Musculoskeletal / Ortho No underlying causes
Neurologic No underlying cause
Nutritional / Metabolic No underlying cause
Obstetric/Gynecologic No underlying cause
Oncologic No underlying causes
Opthalmologic No underlying causes
Overdose / Toxicity [No underlying causes
Psychiatric No underlying causes
Pulmonary No underlying causes
Renal / Electrolyte No underlying causes
Rheum / Immune / Allergy No underlying causes
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous No underlying causes

Causes in Alphabetical Order

See also

References

  1. Physiology at MCG 3/3ch7/s3ch7_5
  2. Blacher J, Staessen JA, Girerd X, Gasowski J, Thijs L, Liu L, Wang JG, Fagard RH, Safar ME. Pulse pressure not mean pressure determines cardiovascular risk in older hypertensive patients. Arch Intern Med 2000 Apr 24;160(8):1085-9. PMID 10789600




Linked-in.jpg