Hypertension: Diagnosis and Treatment

Diagnosis

Sustained and untreated high blood pressure may lead to end–organ damage, including left ventricular hypertrophy, congestive heart failure (of which hypertension is the leading cause in developed countries), stroke, retinopathy, and kidney disease. Therefore, it is important that hypertension be diagnosed and treated early.

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure² defines normal blood pressure as less than 120/80 mm Hg. Prehypertension is defined as a blood pressure between 120/80 and 139/89 mm Hg. This range signals increased risk for progression to hypertension and requires regular monitoring. Further, blood pressure of at least 130/85 mm Hg is a component of the metabolic syndrome.³ Hypertension is defined as an average seated blood pressure measurement of 140/90 mm Hg or greater during 2 or more office visits. Stage 1 hypertension is defined as a systolic blood pressure measurement of 140 to 159 mm Hg and a diastolic measurement of 90 to 99 mm Hg. Stage 2 hypertension is defined as a systolic measurement greater than 160 mm Hg or a diastolic measurement greater than 100 mm Hg.

Hypertensive crisis involves a diastolic pressure greater than 120 to 130 mm Hg.

Hypertensive urgency involves elevated blood pressure without end–organ damage, and hypertensive emergency is characterized by end–organ damage.⁴

Treatment

Goal blood pressure is less than 140/90 mm Hg, or less than 130/80 mm Hg for patients with uncomplicated diabetes or chronic kidney disease. The target for complicated diabetes is less than 125/75 mm Hg.

Prehypertension usually does not require drug therapy unless the patient is at high risk for a cardiac event. High–risk patients include those with coronary heart disease, diabetes, heart failure, chronic kidney disease, or a history of stroke. Nonetheless, lifestyle interventions should be instituted and the patient should be encouraged to monitor blood pressure at regular intervals.

Lifestyle modifications are an integral initial step in the treatment of hypertension. These may include a low–sodium, low–fat, vegetarian diet, maintenance of appropriate body weight, smoking cessation, reduction in alcohol use, increased physical activity, and possibly stress reduction (eg, through meditation or yoga).

Pharmacologic therapy includes the following:

A thiazide–type diuretic is often prescribed as first–line pharmacotherapy.  Such drugs are relatively inexpensive. Potential adverse effects include hypokalemia and erectile dysfunction.

Other drug classes that can be used in mono– or combination–therapy include the following:

• Beta–adrenergic receptor blockers serve as optimal treatment post–myocardial infarction. However, they should be avoided in patients with reactive airway disease or second– or third–degree heart block.
• Calcium channel blockers protect against recurrent myocardial infarction and/or stroke. They may cause pedal edema and/or conduction abnormalities.
• Angiotensin–converting enzyme (ACE) inhibitors are advantageous in patients with diabetes, diabetic nephropathy, post–myocardial infarction, and heart failure. Side effects include cough and angiodema. They are contraindicated in pregnant women.
• Angiotensin receptor blockers (ARBs) have similar benefits to ACE inhibitors (patients who suffer side effects of ACE inhibitors, notably cough, are often switched to ARBs).  They are also beneficial for patients with early renal insufficiency.  
• Alpha–adrenergic blockers are indicated in patients with concomitant benign prostatic hyperplasia, because of their vasodilatory action on both blood vessels and prostatic smooth muscle. This class of drug is associated with a risk of postural hypotension.
• Arterial vasodilators include specific drugs that have noteworthy side effects: hydralazine may cause lupus syndrome, while minoxidil may cause sodium and water retention and hirsutism.
• Potassium–sparing diuretics are optimal for patients at risk of hypokalemia. However, close monitoring of potassium levels is required.

Treatment of hypertensive urgencies often involves a combination of oral medications, whereas hypertensive emergencies require hospitalization and IV therapy.

Asymptomatic hypertension with ventricular dysfunction should be treated with ACE inhibitors, ARBs, and/or beta–blockers. Patients who are symptomatic or have end–stage heart disease should also be treated with digoxin, loop diuretics, and/or aldosterone blockers (eg, spironolactone).

Patients with chronic kidney disease also benefit from ACE inhibitors and ARBs, sometimes in combination.

Pregnant women should be given methyldopa, beta–blockers, or vasodilators such as hydralazine.

Individuals with inadequate responses to single–drug treatment will require combination therapy. Most patients require at least two drugs to achieve target blood pressure, and the use of three or more drugs is common.

It may also be noteworthy that people with hypertension have lower melatonin levels than those with normal blood pressure,⁵ and some fail to experience the normal nocturnal decrease in blood pressure.⁶ In limited studies, melatonin supplements (2.5 mg at bedtime) lowered nocturnal blood pressure significantly (6 mm Hg and 4 mm Hg for systolic and diastolic, respectively) in men with high blood pressure.⁷ An assessment of their clinical value awaits further studies.