HTN DYNAMICS
Most high BP is called “essential” HTN, (also called primary hypertension). Over one third of us in America have HTN. It is higher in men than women until 55 years of age. Women who take birth control pills, are obese, or elderly, are three times more likely to have high blood pressure. Two thirds of people with high blood pressure are now being treated, and only half of those treated have good results with controlling their blood pressure . You are more likely to have HTN, if you have diabetes, had a stroke, have high cholesterol, metabolic syndrome, chronic kidney problems, or peripheral or coronary vascular disease.
Your systolic blood pressure is determined by how stretchable your aorta is. Your blood volume and artery stiffness determine blood pressure levels. Two thirds of your blood is found in the veins and the remaining being one third is in your arteries. As we get older, our arteries lose their elasticity: This causes a greater rise in systolic BP and puts an extra burden on your heart muscle. Increased pressure waves now travel faster in your blood vessels leading to increased pressure waves also in your peripheral arteries. Stiffening of your aorta is increased if you have diabetes, or calcification in your arterial walls. The blood vessels elastic fibers become fragmented, and calcium is deposited on the walls of your arteries. Smoking, diabetes, and chronic kidney disease also cause increased calcium deposits in the arterial walls.
Your blood pressure is lower at rest then when you are active. It goes up just before you wake up, stays elevated in the morning, and goes down at night. There is a drop in the early afternoon and also at 3 AM while you are sleeping. The 3 AM dip is not present if you have had a heart attack, or a stroke. This nighttime drop is also absent if you are very obese, have a sleeping or kidney disorder, or are eating a lot of sodium and very little in low potassium foods.
A high blood pressure is dangerous as in an overinflated tire. An increase pressure wears out your tire, and so does an inflated blood pressure-- increaseing your risk for stroke, heart attack, kidney trouble, and abdominal aneurysm. Repeated measurements, at least three at different times of the day, should be taken before you are labeled “a hypertensive”.
Your blood pressure is read as having two numbers (i.e. 120/50). If both numbers go above 140/90, you have high BP. After 50 of age, if only the larger number goes up,( systolic), you rarely a problem. If your blood pressure is between 120-139/ 80-89 you are at risk to get hypertension. This is called the pre-hypertension stage and should warn you that you must change your lifestyle by exercise, losing weight, and avoiding salt and alcohol. Some people have normal blood pressure in a doctor’s office, but find the blood pressure is elevated outside of the office. This is called “masked hypertension’, is very difficult to diagnose, and is often seen if you have sleep apnea.
Elevated blood pressure causes vascular problems to your eyes, kidneys, heart, and also cause clotting in your brain (strokes) or in your heart ( infarction). Your risk for these problems occurs well before you have hypertension readings. Your risk doubles for every 20/10 higher BP readings above the level of 115/75.
Chronic kidney trouble is often an unrecognized cause of high BP. As chronic kidney disease progresses, virtually everyone will be hypertensive. The number of kidney glomeruli decrease because of injury, and the ones that are left, must increase their filtering function to keep your water removal constant. It does this by promoting an increase in blood pressure. Over time, this elevated BP causes further glomerular damage.
As sympathetic nervous activity increases, the filtration rate of your glomerular decreases. Renin an enzyme that makes angiotensin,is produced. The renin is a potent vasoconstrictor that also promotes salt and water reabsorption. As your sodium is retained, so is the water, and your vascular volume subsequently increases your blood pressure.
Diabetes is the leading cause of chronic kidney disease and results in over 40% of terminal kidney disease. Chronic kidney disease just doesn’t cause high blood pressure, but also increases your risk of a cardiovascular episode. If you have the combination of chronic kidney disease, high BP, and diabetes, you have an extremely high risk for coronary vascular death. A recent survey showed that only one third of people with high blood pressure ever get it lowered to less than 130/80.
Increasing blood pressure contributes to drop in kidney function. It is extremely important that blood pressure be controlled. If you have type II diabetes, you must limit your salt, take a diuretic, and probably an antihypertensive,ACE.
When you are older you need your systolic blood pressure elevated. Since your vessels stiffen with age, you need a higher systolic pressure to keep these vessels filled. In the past the formula was : “100+ your age”. Not so today.
If you have stiffening of your blood vessels, a rapid drop in your blood pressure can cause ischemia to your heart and other organs. The goal is to gradually lower your blood pressure over several months. How on earth does a doctor kmow that you have stiff arteries? A crude indicator is your advancing age. Once you turn 65, your systolic blood pressure, (top number), rises and the diastolic BP, (lower number, keeps falling. The wider the systolic pressure, ithe stiffer your blood vessels.
Answer is, as you age, the goal is to drop your blood pressure very slowly prevent problems. 11.06.11
