What is a normal blood pressure?
Rishabh Sharma, MD, FACC
Many patients have questions regarding what is the optimal level of blood pressure for them. Some state that their pressure is “less than one-hundred and forty” and therefore is fine, while others are concerned when their pressure exceeds one-hundred and twenty! The truth of the matter is that optimal blood pressure control is different for each patient and must be tailored specifically to each one.
First, we must understand what those “top” and “bottom” numbers are. The “top” number is the systolic pressure and the “bottom” is the diastolic. So what does that mean? Systole is the period in the heart cycle when the heart is actively pumping blood, while diastole is the period when the heart is done pumping and is refilling with blood, getting ready for the next beat. Many people are surprised to know that diastole actually takes twice as long as systole, and comprises 2/3 of the cardiac cycle, and therefore an abnormal diastolic blood pressure is just as important in the generation of disease states as the systolic pressure. Both numbers are also largely dependent on the general “tone” of the arteries in the body, which are the conduits through which the heart pumps blood to supply the organs and tissues of the body.
Now that we have that out the way, what pressure should you shoot for? In general, it is recommended that most physicians follow certain published guidelines. One major one is the JNC VIII guidelines. According to these, blood pressure should be targeted specifically to each patient, but a general rule of thumb for most persons is less than 140/90. This is at rest for 5 minutes in a sitting position (the standard way blood pressure is taken). If one has just exercised or performed some strenuous activity (such as driving in traffic) then one should probably wait a little longer, say 20 minutes before taking the measurement. If you are older than 60 your target will be 150/90. If you have diabetes, kidney (renal), heart, or peripheral vascular disease, your target will be more aggressive (less than 140/90) regardless of your age since these patients have a higher risk of developing serious conditions such as heart attacks and strokes.
Finally, how is your blood pressure treated if it is high? This is a little more complicated matter as there are many drug regimens out there which are better suited to particular populations of patients. For example, an African-American may do better with a type of medicine called a calcium-channel blocker versus a Caucasian-American; a patient with kidney disease would be well served on an ace-inhibitor. This is a decision best left to discuss with your physician since certain medications have compelling indications for some, while for others they may actually be harmful.