What Can Doctors Learn from a Systolic-Diastolic Ratio?

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  • Written By: Franklin Jeffrey
  • Edited By: Rachel Catherine Allen
  • Last Modified Date: 24 October 2019
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In most doctors' offices, a patient's vital signs will be taken before the physician enters the examination room. One of the readings that will be recorded is the patient's blood pressure, which is expressed as the systolic rate over the diastolic rate. The systolic-diastolic ratio tells the doctor how much pressure is being exerted on the arteries when the heart contracts and relaxes. High blood pressure is a potentially dangerous condition in itself, but the systolic-diastolic ratio can also warn the doctor that the patient may have a problem with his heart, kidneys or circulatory system. Abnormally low blood pressure may be a symptom of dehydration, internal bleeding, certain inflammatory diseases or heart disease.

A heartbeat consists of two separate actions. The heart contracts, forcing blood out of the heart so that it can circulate throughout the body. This is the systolic phase. Following the contraction, the heart relaxes to allow blood to enter its chambers. The relaxed stage is known as the diastolic phase.


When analyzing a patient's blood pressure, the doctor will look at each number as well as the systolic-diastolic ratio. In patients over the age of 50, doctors normally pay more attention to the systolic number. As people age, the systolic rate normally increases as a result of plaque building up in the arteries and a tendency for the arteries to stiffen over time. If the systolic-diastolic ratio is greater than 140/90, the doctor knows that the patient may have high blood pressure.

If a younger patient displays a high systolic-diastolic ratio, the doctor may suspect an underlying condition may be causing the higher blood pressure. The doctor may evaluate the patient for a heart valve defect or ask if the patient is experiencing any symptoms of kidney disease. As blood pressure can vary a great deal from day-to-day or by the time of day, more than one reading is often needed to make a diagnosis.

Patients with an abnormally low systolic-diastolic ratio may need to be evaluated for internal bleeding. Ulcers and injuries are common causes of internal bleeding, as are aneurysms, or weaknesses in the walls of blood vessels, which can cause internal bleeding if they burst. Certain diseases, such as pancreatitis and diverticulitis, may also cause internal bleeding. The patient's blood pressure reading may provide the doctor with information pointing to one of these conditions.

Although a doctor may learn a great deal from a patient's systolic-diastolic ratio, blood pressure alone is not enough to allow a diagnosis. The doctor will also listen to the patient's heart, check his pulse rate, listen to his breathing and ask questions about other possible symptoms. Other vital signs, such as the patient's temperature and weight, will also be included in the doctor's evaluation.


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Post 1

"Patients with an abnormally low systolic-diastolic ratio may need to be evaluated for internal bleeding." etc. There is very little here about the actual ratio, which would be the figure from dividing the systolic by the diastolic, often about 1.6.

Does that sentence really refer to the ratio, or to the two figures? For example, 80/50 would be a low blood pressure, but the ratio would be quite normal at 1.6.

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