Hypertension, high blood pressure, has been recognized as a clinical entity since the late 1800’s. Accurate blood pressure measurements started after the invention of the sphygmomanometer, the blood pressure cuff, in 1896. Hypertension is a major factor in heart disease and stroke and has been intensively studied for more than 100 years. Despite all of the years of research, 90-95% of hypertension is still deemed idiopathic; doctors don’t know what causes it in the vast majority of cases. Given that background, what could possibly be new in the field of hypertension? Apparently a lot. The discussion first gives some background on hypertension, and then delves into new findings.
What is the definition of high blood pressure?
In late 2017 the American College of Cardiology published new guidelines redefining the threshold for high blood pressure. In the new system, blood pressure is considered elevated if the systolic pressure is over 120 and the diastolic pressure is over 80. Stage 1 hypertension occurs with blood pressure over 130/80. Stage 2 hypertension is defined as a blood pressure of 140/90 or greater. All patients with blood pressure over 120 should be treated initially with lifestyle modification (to be discussed). Those with blood pressure over 140/90 should be started on medication. In addition, medications are recommended for patients with systolic pressure > 130 and who already have established heart disease or those whose estimated ten year cardiac risk is greater than 10% (based on the cardiovascular risk calculator cvriskcalculator.com). Hypertension is diagnosed if blood pressure readings are elevated on three separate occasions, several weeks apart.
"My blood pressure is all over the place"
Blood pressure is never a single, solid, static number. Blood pressure will vary with the time of day, activity and after taking medications. Think of the blood pressure as waves on the ocean, it will have highs and it will have lows. It is best to avoid wild swings between the peak and the trough.It is desirable to have gentle waves with small swings from high to low; this represents a well-controlled blood pressure. Very high blood pressure readings, followed by very low blood pressures, like tsunami waves, are not good as large fluctuations are associated with an increased risk for heart disease..
Where is the best place to measure the blood pressure?
The doctor’s office is not the ideal location for blood pressure checks. Patients are often stressed about getting to the office on time and are often nervous. They are rushed into the exam room, and not given time to relax. These measurements may not be a true reflection of the blood pressure. More accurate readings occur when patients take their blood pressure at home, where they are relaxed and comfortable. Another reliable method is an ambulatory blood pressure monitor, a blood pressure cuff worn for 24 hours, which gives an average blood pressure reading during the day and at night. Both methods, home blood pressure readings and an ambulatory blood pressure monitor, can confirm hypertension in patients who have high readings in the office or white coat hypertension (high readings in the office but normal at home) to avoid over diagnosis and over treatment. In addition, ambulatory blood pressure monitoring is a stronger predictor of cardiac disease and mortality than office blood pressure values.
When is the best time to take blood pressure medication, in the morning or at night?
The blood pressure normally varies through the course of a day. It is highest in the mornings when hormones are secreted that arouse us from sleep and stimulate us to get us ready for the day. The blood pressure is at its lowest when are sleeping. This is significant because the mean blood pressure during sleep is a more important indicator of cardiovascular disease than daytime office blood pressure or the average blood pressure over a 24-hour period. Recent research has shown that taking blood pressure medication at night controls the blood pressure better and lowers the risk for cardiovascular events compared to taking meds in the morning. Taking medication at night also reduced the risk of kidney disease and lowered the cholesterol.
Which is more important, the upper (systolic) number or the lower (diastolic) number?
Systolic blood pressure is the force of the blood pumped by the heart into the aorta, the main artery leading from the heart. It is the force the heart pumps against. The higher the systolic blood pressure, the harder the heart has to work to get blood to the body. The diastolic number is the pressure in the heart and aorta after a heartbeat, when the circulatory system is relaxing. A high diastolic blood pressure means that the heart cannot relax properly. For hypertension, which number is more important to follow? Since the Framingham Heart Study published their results in the 1960’s, it has been felt that the systolic level was more important. In fact, the American College of Cardiology risk calculator uses systolic blood pressure as a variable, but doesn’t ask for the diastolic number. However, new research has shown that systolic and diastolic blood pressure are each independently associated with cardiovascular outcomes. Even though systolic pressure had a greater effect, diastolic readings should not be ignored.
Which is better, a wrist blood pressure cuff or an arm cuff?
The blood pressure reading taken from the upper arm is not equal to the blood pressure in the wrist. Again, if we think of blood pressure as a wave, a certain pressure is needed to get blood to the arm. The wave then propagates and a higher pressure is needed to get blood to the hand and fingers. New research has shown that the systolic blood pressure averaged 5.5 mmHg higher in the wrist than in the upper arm. Many people had a blood pressure difference greater than 15 mmHg. This has implications for home blood pressure monitors. It must be kept in mind that wrist cuffs will give higher readings than arm cuffs.
Is alcohol good or bad for the blood pressure?
The American Heart Association recommends no more than two alcoholic drinks per day for men and one for women. Is that a safe amount for a patient with hypertension? A drink is defined as 12 ounces of beer, 4 ounces of wine or 1 ounce of spirits. Many studies have shown that heavy drinkers (> 14 drinks per week) are more likely to have high blood pressure than nondrinkers. New research has shown that moderate drinkers (7-13 drinks per week), a range within the American Heart Association guidelines, are 1.5 to 2 times more likely to have hypertension. In addition, binge drinking (4-5 drinks within a two hour period) also is associated with hypertension, even if consumption is low at other times. However, all is not lost. Light drinkers (1-6 drinks per week) did not have elevated blood pressure.
Diet and exercise are first line treatments for hypertension. How well do they work?
After a diagnosis of hypertension is made, lifestyle intervention is started and includes diet, exercise, weight loss, decreasing alcohol intake and smoking cessation. Cardiologists are taught that blood pressure increases with age. However a new study questions that teaching. When looking at two communities in the Venezuelan rain forest, researchers concluded that diet rather than advancing age caused high blood pressure. Blood pressure readings that go up with age may not be from aging, but rather the effect of a poor diet building up over time or genetics. Another study showed how detrimental a Southern diet (a diet high in fried food) is for the development of hypertension, especially in African-Americans. Diet is so important that just by following the DASH (Dietary Approaches to Stop Hypertension) diet, one can expect to lower the systolic pressure by 11 points and the diastolic pressure by 8 points. These reductions are as good as those achieved with some medications.
Exercise lowers blood pressure to the same degree as diet and an expensive gym membership is not needed. One recent study showed that a brisk morning walk of about 30 minutes lowered blood pressure in obese adults. Blood pressure is down immediately after the walk and the effect lasts for 8 hours afterwards. On the other hand, another study concluded that men should exercise at night to lower their blood pressure. So which is it, morning or evening exercise? Very likely the time of day matters less than actually doing exercise. Any type of exercise, at any time of day, is better than being sedentary. Lastly, a huge review of nearly 400 studies evaluating nearly 40,000 patients showed that exercise lowers blood pressure by about 9 points, again similar to medication.
If you have hypertension, the choice is simple: medication or lifestyle changes. Lifestyle modification is a good place to start as this can lower blood pressure, is less risky and makes economic sense. You can send your hard earned cash to the pharmaceutical companies or spend it on fresh fruits and vegetables (DASH diet), drink less alcohol (saving more money) and exercising (which can easily be done for $0). Start with lifestyle changes but keep in mind medication may still be necessary as you work with your doctor to lower your blood pressure.
