Pulse Pressure - Wikipedia

Low (narrow) pulse pressure

A pulse pressure is considered abnormally low if it is less than 25% of the systolic value.[2] If the pulse pressure is extremely low, i.e. 25 mmHg or less, it may indicate low stroke volume, as in congestive heart failure.[3]

The most common cause of a low (narrow) pulse pressure is a drop in left ventricular stroke volume. In trauma, a low or narrow pulse pressure suggests significant blood loss.[8]

A narrow pulse pressure is also caused by aortic stenosis.[3] This is due to the decreased stroke volume in aortic stenosis.[9] Other conditions that can cause a narrow pulse pressure include blood loss (due to decreased blood volume), and cardiac tamponade (due to decreased filling time). In the majority of these conditions, systolic pressure decreases, while diastolic pressure remains normal, leading to a narrow pulse pressure.[9]

In the Postural Orthostatic Tachycardia Syndrome it is postulated that declining venous return reduces stroke volume and frequently results in low pulse pressure. In extreme cases, patients experience a drop in pulse pressure to 0 mm Hg upon standing, rendering them practically pulseless while upright. This condition leads to significant morbidity, as many affected individuals struggle to remain standing.[10]

High (wide) pulse pressure

Consistently high

A pulse pressure of 50 mmHg or more can increase the risk of heart disease, heart rhythm disorders, stroke and other cardiovascular diseases and events. Higher pulse pressures are also thought to play a role in eye and kidney damage from diseases such as diabetes.[3] There are currently no drugs approved to lower pulse pressure, but some antihypertensive drugs have been shown to modestly lower pulse pressure, while other drugs used for hypertension can actually have the counterproductive side effect of increasing resting pulse pressure.[11]

The aorta has the highest compliance in the arterial system due in part to a relatively greater proportion of elastin fibers versus smooth muscle and collagen. This serves to dampen the pulsatile ejection fraction of the left ventricle, thereby reducing the initial systolic pulse pressure, but slightly raising the subsequent diastolic phase. If the aorta becomes rigid, stiff and inextensible because of disorders, such as arteriosclerosis, atherosclerosis or elastin defects (in connective tissue diseases), the pulse pressure would be higher due to less compliance of the aorta.[12]

In hypertensive patients, a high pulse pressure can often be an indicator of conduit artery stiffness (stiffness of the major arteries).[13] When the arterial walls are stiffer (less compliant), the heart has to beat harder to overcome the resistance from the stiff arteries, resulting in an increased pulse pressure.[14]

Other conditions that can lead to a high pulse pressure include aortic regurgitation,[15] aortic sclerosis, severe iron-deficiency anemia (due to decreased blood viscosity), arteriosclerosis (due to loss of arterial compliance), and hyperthyroidism[15] (due to increased systolic pressure), or arteriovenous malformation, among others.[9] In aortic regurgitation, the aortic valve insufficiency results in the backward flow of blood (regurgitation) that is ejected during systole, and its return to the left ventricle during diastole. This increases the systolic blood pressure, and decreases the diastolic blood pressure, leading to a widened pulse pressure.[9][3]

A high pulse pressure combined with bradycardia and an irregular breathing pattern is associated with increased intracranial pressure, a condition called Cushing's triad seen in people after head trauma with increased intracranial pressure.[16]

Common causes of widening pulse pressure include:[3]

• Anemia
• Aortic dissection
• Atherosclerosis[15]
• Arteriovenous fistula[15]
• Chronic aortic regurgitation
• Aortic root aneurysm[17]
• Aortic root dilation[17]
• Beri beri[15]
• Distributive shock[15]
• Endocarditis
• Fever
• Heart block
• Increased intracranial pressure[16][15]
• Patent ductus arteriosus
• Pregnancy[15]
• Thyrotoxicosis[15]

From exercise

For most individuals, during aerobic exercise, the systolic pressure progressively increases while the diastolic pressure remains about the same, thereby widening the pulse pressure. These pressure changes facilitate an increase in stroke volume and cardiac output at a lower mean arterial pressure, enabling greater aerobic capacity and physical performance. The diastolic drop reflects a reduced systemic vascular resistance of the muscle arterioles in response to the exercise.[18]