What is "Resistant or refractory hypertension" & how to treat it?

Resistant hypertension is high blood pressure that does not respond to treatment. Specifically, hypertension is said to be ‘resistant’ when an individual’s blood pressure remains above the target blood pressure despite administration of an optimal three- drug regimen that includes a diuretic. But a high blood pressure should not be called ‘resistant’ until the three-drug combination therapy has failed. It is due the fact that some cases of high blood pressure are difficult to treat, and may require a combination of multiple drugs for proper control.

Causes- There may be several causes of resistant hypertension, a few of which are the following-

(1) Improper BP measurement- Over inflation of the cuff or use of a cuff too small for the arm may lead to inaccurately high readings.

(2) Calcification or arteriosclerosis - Calcification or arteriosclerosis of the brachial arteries, if heavy, may lead to pseudohypertension as they cannot be fully compressed.

(3) White coat hypertension- This may lead to an unnecessary high reading.

(4) Inadequate medication- Reluctance by patient or by the physician may cause failure to receive adequate doses of medication which in turn may lead to hypertension.

(5) Drug interactions- This may lead to antagonism causing lack of response to the drugs.

(6) Secondary hypertension- This may be a cause which is usually from overactive adrenal glands.

(7) Fluid retention - This may be a cause which is usually due to expansion from renal failure.

Treatment- Resistant hypertension should first of all be confirmed by excluding pseudohypertension & white coat hypertension. As resistant hypertension is usually the result of some underlying cause, treatment should focus on its removal along with the general treatment of resistant hypertension.

(A) General measures-

(1) Withdrawal of interfering drugs -Avoidance of blood pressure elevating drugs , such as non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin if possible.

(2) Changes in patient’s life-style- Weight reduction, reduction of heavy alcohol consumption, salt restriction are some other measures to be taken to combat resistant hypertension.

(B)Drug regimen- The drug regimen should include a diuretic plus near maximal doses of two of the following classes of drugs-

(1) Beta-adrenergic-blocker or other anti-adrenergic agent.

(2) Direct vasodilator.

(3) Calcium channel-blocker.

(4) ACE( Angiotensin Converting Enzyme) inhibitor.

(5) Angiotensin receptor blocker.

(6) Mineralocorticoid receptor antagonist - Of late this drug is being advocated which when added to existing multi-drug regimen provides significant antihypertensive effect. But while using this drug special attention should be given to blood potassium levels as there is chance of hyperkalemia.

Some points to be borne in mind-

(1) Older age & obesity are the two strongest risk factors associated with resistant hypertension.

(2) People with resistant hypertension have a high cardiovascular risk.

(3) These people have often multiple health conditions that complicate their BP management.

(4) Uncontrolled hypertension is not the same as resistant hypertension.

(5) Confirming resistance is the first step towards a successful treatment of resistant hypertension.

(6) Successful treatment of resistant hypertension requires consideration of life-style factors contributing to resistance of treatment, proper diagnosis & treatment of secondary causes of high BP & using multiple drug treatments effectively.

(7) Dose-timing should be adjusted in such a way that at least one of the drugs is taken at bed time.

(8) Drug adherence should be strictly maintained. Patients should take the drugs regularly & properly. It is better to prescribe long-acting combination drugs with once-daily dosing.