by Christian W. Mende, MD
When you at do you think when you hear that someone has high blood pressure? It’s a common misconception that people with high blood pressure are tense, angry, high-strung or “Type A” personalities.
The truth is, blood pressure has nothing to do with personality — and everything to do with cardiovascular health.
With every beat, the heart delivers a volume of blood into the aorta and circulation generating the systolic blood pressure (the first reading, e.g. 120 mmHg). The second part of the blood pressure (BP) recording represents the pressure between heartbeats.
This is called diastolic BP (e.g., 80 mmHg) and represents the resistance to flow of the blood into the periphery — essentially to all the organs and tissues in the arms and legs.
The definition of hypertension (HTN) is arbitrarily set by a Joint Commission of the National Institute of Health. Over the last 40 years the definition has adjusted downward to lower levels. The last guidelines are from 2003 and new guidelines are due in early 2011.
Present guidelines define HTN as a medical office reading of 140/90 mmHg or higher and a home reading of 135/85 and above. However, if there are coexisting conditions such as diabetes, heart and kidney disease, HTN starts at 130/80 and above.
Blood pressure should be obtained with a correctly sized cuff while sitting quietly in a chair with back support, both feet on the floor, and arms resting at table height.
The BP device should be placed at heart level using the arm with the higher reading. The first reading is discarded, and after one-minute intervals the second and third readings are averaged out. BP is usually highest after arising in the morning.
Home BP readings are more important than office BP for predicting cardiovascular events. In one recent study recently office BP was 19/11 mmHg higher than home BP. Because of great variability of BP throughout the day and from day to day, a measurement that is at goal three out of four readings is considered “controlled.”
In the United States, about 72 million people have HTN. It is caused by multiple genetic predispositions and multiple lifestyle factors (obesity, activity, diet, salt intake, etc.). Age is one of the strongest factors; at age 60 about 50 percent have HTN, at age 70 almost 75 percent and at age 90 about 90 percent.
In the last 10 years research has shown that until age 50 the diastolic number is more important. After age 50, the systolic number corresponds better with cardiovascular events and is more important.
We treat HTN to prevent stroke, heart attack, heart failure and kidney function loss, as well as premature arteriosclerosis including dementia. Today, we have non-pharmacological treatment options and over 130 drug combination to choose from.
Provided it is safe to delay drug treatment, weight loss in obesity (BMI of 30 or above,) salt reduction, high fruit and vegetable intake, cessation of smoking, and increased exercise can lead to as much BP reduction as using to drugs (a reduction of 20/10 mmHg).
There are seven classes of drugs for HTN, including diuretics (Hydrochlorothiazide), ACE-inhibitors (Lisinopril, Benazepril), angiotensin receptor blockers (Cozaar, Diovan, Avapro), beta blockers (Atenolol, Metoprolol, Bystolic), calcium channel blockers (Amlodipine, Diltiazem), alpha blockers (Doxazosin) and centrally working drugs such as Clonidine.
For unclear reasons, the average dose of any BP drug class only lowers BP by about 10mmHg systolic, unless the BP is above 170 mmHg. Doubling of drug doses to the maximum recommended dose only lowers BP by an additional five points. Therefore, if your BP is 20 mmHg above goal, you need to be started on two drugs (two or three drugs are available in one dose).
We have no guidelines for people older than 80, but a recent European study showed that a BP goal below 150 mmHg systolic is reasonable. Also, a diastolic BP should not be lowered below 60 mmHg after age 60 because of the possibility of reducing blood flow to the coronary arteries.
This Scripps Health and Wellness information was provided by Christian W. Mende, MD, clinical hypertension specialist at Scripps Memorial Hospital La Jolla.