Blood pressure is the force of blood against the walls of the arteries. The top number, or systole, is a measure of the force of blood against the arterial walls when the heart beats. The bottom number, or diastole, is the force of blood against the arterial walls between beats. A healthy blood pressure should not exceed 120/80.
What can happen if hypertension, or high blood pressure, is not treated? Although hypertension is not painful, so much can go wrong if it is not controlled, that it is known as the silent killer. The three organs most at risk, known as the target organs, are the brain, heart, and kidneys.
The danger to the brain is the risk of cerebrovascular accident (CVA), or stroke, which in severe cases can lead to death. The high pressure can also lead to balloon-like outpouchings of the arteries in the brain, known as aneurysms. These aneurysms are weak and can rupture, causing bleeding into the brain.
Hypertension affects the heart by making it struggle to pump blood through the arteries, which can cause failure. The heart is made up of four chambers, the right and left atria at the top, and the right and left ventricles on the bottom. When blood returns from its journey through the body it enters the right atrium, spills down to the right ventricle, and travels from there to the lungs, where it picks up oxygen. From the lungs it goes to the left atrium, from which it travels down to the left ventricle, and on out through the arteries to oxygenate the body. When the pressure is too high the left ventricle can be unable to pump all its contents out into the arteries. When that happens blood backs up into the left atrium, and from there into the lungs. The lungs can fill with fluid, in a condition known as congestive heart failure. The lungs are not able to take in enough oxygen, due to fluid buildup, and breathing becomes labored. The condition can become fatal if not rapidly relieved.
Hypertension also raises the risk of kidney failure. Many blood vessels go through the kidneys, where they carry blood to be filtered of excess water and waste. When blood pressure is too high these blood vessels become damaged, narrowing in diameter. This does not allow enough blood to enter the kidneys, and chronic kidney disease and end stage kidney failure can result.
Many medications are available for treating high blood pressure:
- Diuretics cause the kidneys to eliminate water, lowering the volume of fluid in the blood vessels. There are three types:
- Loop diuretics act at the ascending loop of Henle in the kidneys
- Lasix (furosemide)
- Edecrin (ethacrynic acid)
- Bumex (bumetanide)
- Potassium-sparing diuretics do not lower blood levels of potassium as loop diuretics do, so patients do not require potassium supplements
- Midamor (amiloride)
- Inspra (eplerenone)
- Dyrenium (triamterene)
- Aldactone (spironolactone)
- Thiazide diuretics help kidneys expel sodium, promoting excretion of urine
- Diuril (thiazide)
- Microzide (hydrochlorothiazide)
- Hygroton (chlorthalidone)
- Natrilix (indapamide)
- Zaroxolyn (metolazone)
- Beta blockers cause the heart to beat more slowly and less forcefully by blocking the hormone epinephrine, also known as adrenaline:
- Tenormin (atenolol)
- Cardicor (bisoprolol)
- Lopressor (metoprolol)
- Inderal (propranolol)
- ACE inhibitors inhibit angiotensin converting enzyme, enlarging arterial diameters:
- Lotensin (benazepril)
- Capoten (captopril)
- Vasotec (enalapril)
- Monopril (fosinopril)
- Zestril (lisinopril)
- Univasc (moexipril)
- Coversyl (perindopril)
- Accupril (quinapril)
- Loop diuretics act at the ascending loop of Henle in the kidneys
- Angiotensin II receptor blockers cause blood vessels to dilate:
- Edarbi (azilsartan)
- Atacand (candesartan)
- Teveten (eprosartan)
- Avapro (Irbesartan)
- Cozaar (losartan)
- Benicar (olmesartan)
- Micardis (telmisartan)
- Diovan (Valsartan)
- Calcium channel blockers prevent calcium from entering cells of heart and arteries, causing both to relax:
- Norvasc (amlodipine)
- Cardizem (diltiazem)
- Plendil (felodipine)
- Dynacirc (isradipine)
- Cardene (nicardipine).
- Procardia (nifedipine)
- Sular (nisoldipine)
- Calan (Verapamil)
- Central agonists work directly upon the brain to stop it from sending signals to the heart and blood vessels to raise blood pressure:
- Tenex (guanfacine)
- Aldomet (methyldopa)
- Catapres (clonidine)
- Wytensin (guanabenz)
- Peripheral adrenergic inhibitors block brain signals telling blood vessels to constrict:
- Hylorel (guanadrel)
- Ismelin (guanethidine monosulfate)
- Serpasil (reserpine)
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