Treatment of Hypertension

Introduction

If the cause cannot be removed, or while awaiting definitive treatment, it may be necessary to lower the blood pressure. The aims of treatment are to lower blood pressure and reverse organ damage without inducing significant side effects. If there is renal disease, then renal function can deteriorate as pressures are lowered.

EMERGENCY TREATMENT

Hypertensive emergencies are those with very high blood pressures or with any of the features discussed earlier. If the blood pressure needs to be lowered rapidly, then the agents listed in Table 22-30 should be considered.

LONG-TERM THERAPY

Because therapy for chronic hypertension may need to go on for years, even for life, it is essential to be sure that therapy is needed and then to commence with simpler forms before using more powerful and more complex drug treatment. It may be prudent to obtain 24-hour blood pressure measurements, which often show that the highest pressure is that in the doctor's office ("white coat hypertension"). Attempts to restore that atypical pressure to normal may lead to unacceptable hypotension.

Reduction of weight is important because obesity is an independent cause of left ventricular hypertrophy. Regular exercise should be encouraged. The patient should avoid smoking and a diet high in saturated animal fats because these factors add to the risk of later atherosclerosis. The diet should be high in potassium, which may help to lower pressures. Salt should be restricted, but because not all hypertensives are salt sensitive, the restriction can be relaxed if it is found not to lower pressure. Recent studies suggest that the chloride in salt causes the pressure elevation.

Psychotherapy to help the patient deal with stresses may be of value.

Sedative drugs such as barbiturates or benzodiazepines (Valium) can be very helpful, provided that they are used with precautions about excessive sedation and the risk of addiction.

PRINCIPLES OF DRUG THERAPY

Hypotensive drugs may work at one or more levels in the body to lower cardiac output or cause systemic arterial vasodilatation (Table 22-31).

Often the primary action is partly or completely counteracted by compensatory changes. For example, vasodilatation may cause a rise in heart rate and cardiac output that returns pressure to its former level, and this may also happen if a fall in cardiac output causes reflex vasoconstriction.