Hypertension

The National Heart, Lung and Blood institute has estimated that half of the people with high blood pressure are unaware of the condition. Hypertension is a silent killer because it is often symptom free. High blood pressure is the major cause for heart failure, stroke and kidney failure. Hypertension is defined as persistent levels of blood pressure in which the systolic pressure is above 140 mm Hg and the diastolic pressure is above 90 mm Hg.

Hypertension is a lifetime condition. About 20% of the adult population develop hypertension; Out of which more than 90% of them have essential or primary hypertension, that has no medical cause. The rest of them develop secondary hypertension where there is blood pressure elevation with specific cause like narrowing of the renal arteries, organ dysfunction, certain medications, tumors and pregnancy.

Blood pressure is classified into 4 stages for adults aged 18 years and older. They are
Stage 1 (mild) - systolic 140-159 and diastolic 90-99
Stage 2 (moderate) - systolic 160-179 and diastolic 100-109
Stage 3 (severe) - systolic 180-209 and diastolic 110-119
Stage 4 (very severe) - systolic >210 and diastolic >120

A person with hypertension is usually symptom free until some vessel damage occurs. Physical examination may reveal no abnormalities, but some changes may be noted in retina, such as hemorrhages, exudates, narrowed arterioles and papilledema. The manifestations are related to the organ systems served by the involved vessels.

A thorough history, physical examination (retina), lab studies (electrocardiography, renogram, intravenous pyelogram, renal arteriogram, renal function studies, renin levels,protein in the urine, blood urea nitrogen) are performed to confirm the diagnosis.

Blood pressure can be kept under control by nonpharmacological methods, including weight reduction, restriction of alcohol, sodium and tobacco, exercise and relaxation. The antihypertensive drugs are selected by the doctor depending upon the effectiveness, chance of acceptance by the person and fewer side effects.

The medication therapy for hypertension includes diuretics, adrenergic inhibitors, vasodilators, angiotensin-converting enzyme (ACE) inhibitor and calcium antagonist. There are three major divisions under diuretics namely thiazide diuretics, loop diuretics and potassium sparing diuretics. These are used in combination with other antihypertensive drugs. Reserpine, methyldopa, propranolol, prazosin hydrochloride, clonidine hydrochloride, metoprolol, nadolol, guanethidine, labetalol hydrochloride and phentolamine mesylate are some of adrenergic inhibitors used in regular treatment. The major action of these adrenergic inhibitors is to block or prevent the release of norepinephrine from adrenergic receptors.

Hydralazine hydrochloride, minoxidil, sodium nitroprusside and nitroglycerin diazoxide are a few vasodilators used to decrease peripheral resistance and cause peripheral vasodilation by relaxing smooth muscles. Captopril, a ACE inhibitor prevents conversion of angiotensin 1 to angiotensin 2 and thereby decreases the blood pressure. Diltiazem hydrochloride, nifedipine and verapamil are calcium antagonist that inhibits calcium ion influx across membranes and reduce cardiac afterload.

Hypertension is a lifetime condition and so should the treatment be. Treatment should not be discontinued abruptly.