What Happens When Diastolic Blood Pressure Is High?

A blood pressure reading measures how much pressure is exerted against the artery walls as the heart pumps blood through the body. The top blood pressure reading is the systolic pressure, which represents how much force the heart exerts when it contracts. The second number is the diastolic pressure, which represents the level or pressure when the heart relaxes. The American Heart Association identifies readings below 120/80 as normal. Systolic readings over 140 or diastolic readings over 90 are classified as hypertension.

Historically, more attention has been placed on the health risks of elevated systolic blood pressure readings. But high diastolic readings, whether in isolation or along with high systolic readings, are also unhealthy for the body. A study of over 1900 adults, published in the March 2014 issue of "Journal of Hypertension," linked elevated diastolic and systolic readings to an increased risk of a cardiovascular event -- such as chest pain or heart attack. A review of the medical records of 1.25 million people, reported in the May 2014 issue of "The Lancet," provided additional clarification on the health effects of elevated systolic and diastolic readings. Study authors concluded that elevated systolic blood pressure posed a higher risk of heart disease-related chest pain as well as stroke caused by brain bleeds, while high diastolic blood pressure was linked to a greater risk of abdominal aortic aneurysm -- an enlargement of the body's main artery which can leak or burst and cause life-threatening complications. The health risks seem to extend beyond heart health, as a study published in the August 2009 issue of "Neurology" linked a 10 point increase in diastolic blood pressure to a 7 percent reduction in cognitive decline.

Elevated diastolic blood pressure, without abnormal systolic pressure, is called diastolic hypertension and is more common in adults under the age of 45. In these younger adults, diastolic hypertension poses a greater risk of death from heart disease compared to high systolic blood pressure, according to a February 2011 report published in "British Medical Journal." In addition, people with high diastolic blood pressure are more likely to develop elevations in systolic pressure as they age, which increases future heart disease and stroke risk. This underscores the importance of blood pressure management and medical follow-up in anyone with elevated diastolic readings.

If your systolic or diastolic blood pressure readings are above normal range, work with your doctor on a treatment plan which may include medications and lifestyle changes such as healthy diet, weight loss and exercise. High blood pressure is often called the silent killer because it generally causes no symptoms, but can lead to serious health consequence or death . It's important to have your blood pressure checked regularly or purchase a monitor so you can track your readings at home, and to diligently follow your treatment plan. While normal blood pressure readings are below 120/80, your doctor can provide you with individualized blood pressure targets. Seek immediate medical attention if you develop chest pain, shortness of breath, or have a sudden onset of weakness, vision changes, difficulty speaking or back pain. Systolic blood pressure readings above 180, or diastolic readings above 120 -- or above 110 with symptoms -- are considered a medical emergency and require immediate treatment.

Reviewed by Kay Peck MPH RD