A pulse pressure is abnormally small (“narrow”) if <25% of the systolic value. Hence, a patient with a
systolic of 100 mmHg and a diastolic of 90 has a narrow pulse pressure of 10. The most common cause
is a drop in left ventricular stroke volume because of obstruction to left ventricular filling (tamponade,
constrictive pericarditis) or emptying (aortic stenosis, even though this usually presents with normal pulse
pressure). It may also occur in a tachycardia so severe to reduce ventricular filling time, and in shock (because of increased peripheral vascular resistance).
systolic of 100 mmHg and a diastolic of 90 has a narrow pulse pressure of 10. The most common cause
is a drop in left ventricular stroke volume because of obstruction to left ventricular filling (tamponade,
constrictive pericarditis) or emptying (aortic stenosis, even though this usually presents with normal pulse
pressure). It may also occur in a tachycardia so severe to reduce ventricular filling time, and in shock (because of increased peripheral vascular resistance).