Resistant hypertension is defined in JNC 7 as the failure to reach blood pressure control in patients who are adherent to full doses of an appropriate three-drug regimen (including a diuretic). In this situation, the clinician should first exclude potential identifiable causes of hypertension (Table 11-3), and then carefully explore reasons why the patient might not be at goal blood pressure (

Table 11-11). The clinician should pay particular attention to the type of diuretic being used in relation to the patient’s renal function. If goal blood pressure cannot be achieved by these measures, consultation with a hypertension specialist should be considered.

Resistant hypertension is high blood pressure that does not respond to treatment. Specifically, resistant hypertension is defined as blood pressure that remains elevated above treatment goals despite administration of an optimal three drug regimen that includes a diuretic. Because some cases of high blood pressure are difficult to treat, and may require a combination of multiple drugs before control is established, high blood pressure cannot be called “resistant” until this three-drug combination therapy has failed.

How is Resistant Hypertension Diagnosed?

Resistant hypertension is diagnosed when the blood pressure continues to be elevated despite trying combination therapy with three drugs. The standard guidelines state that:

  * Proper blood pressure measurement technique must be used
  * The size of the blood pressure cuff should be double checked for accuracy
  * The blood pressure readings must be recorded on two separate occasions

What Causes Resistant Hypertension?

There are many things that can cause resistant hypertension, and proper medical testing is required to investigate each of these potential causes. The three most common causes of resistant hypertension are:

  * Patient noncompliance with treatment
  * Secondary hypertension (Usually from overactive adrenal glands)
  * Fluid retention (usually expansion from kidney failure)

Additionally, it is important to make sure that what appears to be resistant hypertension isn’t actually pseudohypertension or white coat hypertension.

The most common cause of resistant hypertension, and the most difficult to treat, is what medical researchers commonly refer to as “patient noncompliance.” The term “patient noncompliance” refers to instances where patients are not adherent to the prescribed treatment, but is not meant to imply the patient is always to blame. To the contrary, most cases of “noncompliance” actually indicate that circumstances not in the patient’s control have made following the recommended therapy either impractical or intolerable.

For example, patients are sometimes placed in situations where the recommended medication is too expensive, or the pharmacy is very far away, or doctor appointments are difficult to keep. More commonly, prescribed medications may have side effects, like headache or upset stomach, of sufficient strength that the patient will stop taking the prescribed medicine to avoid suffering them. When side effects occur, the doctor usually changes to a medicine that is better tolerated. But what happens if you’ve tried all the different medicines and the only one that works is the one that gives you the worst upset stomach? Clearly, situations like this require a great deal of thoughtful problem solving.

Resistant Hypertension: Diagnosis and Management
The incidence of resistant hypertension, the failure to reduce blood pressure below 140/90 mm Hg, despite the use of 3 antihypertensive medications at optimal doses including a diuretic, is estimated to be less than 5% of the hypertensive population.

Resistant hypertension increases the risk of stroke, myocardial infarction, congestive heart failure, and renal failure. Evaluation of the patient with resistant hypertension should include 24-hour ambulatory blood pressure monitoring or home measurements and a limited search for secondary causes. Treatment should focus on optimizing the drug regimen in a logical way, based on the patient’s comorbidities and tolerability. Long-acting, well-tolerated once-daily medications are preferred, and the regimen should include in sequence a diuretic, β-blocker, angiotensin-converting enzyme/angiotensin receptor-blocker inhibitors, and a calcium-channel blocker. This article reviews the definitions and causes and provides specific recommendations for the evaluation and management of patients with this life-threatening condition

Dimitris P. Papadopoulos, MD
Hypertension and Cardiovascular Research Clinic, Georgetown University/VAMC, Washington, DC, .(JavaScript must be enabled to view this email address)

Vasilios Papademetriou, MD
Hypertension and Cardiovascular Research Clinic, Georgetown University/VAMC, Washington, DC