What is Treatment-Resistant Hypertension?
Resistant hypertension, or treatment-resistant hypertension, refers to high blood pressure that does not respond to treatment. Patients with treatment-resistant hypertension usually have blood pressure readings around 130/80 mmHg or higher despite being on medication. Healthy levels are usually around 120/80 mmHg
Hypertension is most often considered treatment resistant in people who are unable to achieve their blood pressure goals despite taking at least three high blood pressure medications. Some hypertensive patients may also be considered treatment resistant if their blood pressure is controlled on four or more medications.
One of these medications is usually a diuretic, which helps the body shed excess salt and water in order to lower blood pressure. Other medications include angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs).
Who is at Risk of Treatment-Resistant Hypertension?
People with secondary hypertension (hypertension caused by an underlying health condition) are frequently at risk of developing treatment-resistant hypertensio n. Some of these underlying conditions, such as primary aldosteronism, change how hormones are produced in the body, which have a direct effect on blood pressure. Other conditions that can cause resistant hypertension include chronic kidney disease (CKD) or diabetes.
Other factors that can contribute to the development of treatment-resistant hypertension include the following:
- Plaque buildup in veins and arteries
- Sleep conditions such as sleep apnea
- Obesity, diet, and alcohol consumption
- Poor adherence to hypertension medications
- Old age
Treating secondary hypertension requires addressing both the underlying health condition and the hypertension it causes, making it much harder to get high blood pressure back to a healthy level.
What are the Symptoms of Treatment-Resistant Hypertension?
Treatment-resistant hypertension usually doesn’t cause any symptoms. High blood pressure in general rarely does. That’s why hypertension has often been referred to as the “silent killer.”
In some cases, sudden increases in blood pressure can cause dizziness, headaches, or shortness of breath. These situations require emergency care.
What are the Complications of Treatment-Resistant Hypertension?
Left untreated, hypertension can cause a range of complications. including damage to the heart and brain. Chronic hypertension can also make veins, arteries, and heart tissue less flexible, making it harder for blood to move around the body. As a result, the heart may not be able to pump effectively (heart failure), increasing the risk of cardiovascular health problems, such as heart attacks, atrial fibrillation, and sudden cardiac arrest.
Treatment-resistant hypertension can also affect renal (kidney) function. Renal artery stenosis and CKD are two common conditions that can both cause and be a cause of hypertension.
Renal artery stenosis causes blood vessels that bring blood to the kidneys to narrow. High blood pressure can damage these blood vessels, making treatment-resistant hypertension a risk factor for developing renal artery stenosis.
CKD is characterized by the reduced ability of kidneys to filter blood. The presence of aldosterone, specifically, plays a big role in the pathogenesis of CKD. Aldosterone, a hormone that plays an important role in the body’s renin-angiotensin-aldosterone system (RAAS), plays a role in water and salt retention and increasing blood pressure. It can also cause inflammation and fibrosis, leading to CKD.
How is Treatment-Resistant Hypertension Diagnosed?
Diagnosing treatment-resistant hypertension can be challenging. An accurate diagnosis requires effective clinical techniques to avoid diagnosing hypertension as pseudoresistant instead of treatment resistant. Pseudoresistant hypertension means someone presents with all the signs of treatment resistant-hypertension, but there are other factors affecting blood pressure that don’t qualify.
The most common factors that can complicate a diagnosis include ineffective blood pressure measurement techniques or a lack of adherence by patients to their medications.
White coat hypertension, in particular, is an important factor to consider when making a diagnosis. Once thought to be the result of situational increases in blood pressure due to anxiety or stress, white coat hypertension could skew blood pressure readings and suggest treatment-resistant hypertension. For example, a patient taking multiple hypertension medications who has a high blood pressure in a clinic would appear to have treatment-resistant hypertension. However, patients often have much lower blood pressure while at home, suggesting that a patient doesn’t actually have treatment-resistant hypertension.
That’s why measuring ambulatory blood pressure (or blood pressure while moving around) has become a key way of identifying true treatment-resistant hypertension. Patients may be asked to wear a 24-hour blood pressure monitor, which can gather regular fluctuations in blood pressure. Capturing blood pressure throughout a day can help rule out certain abnormalities in measurements.
Measuring blood pressure in real-time settings versus a clinic is also a helpful way of ongoing treatment and monitoring.
How is Treatment-Resistant Hypertension Treated?
While hypertension becomes resistant because it doesn’t respond well to medications, there are still ways to manage this condition and reduce complications. After treatment-resistant hypertension diagnosis is made, doctors usually add a mineralocorticoid receptor antagonist (MRA) to a patient’s treatment regimen. MRAs target the production of aldosterone, a hormone triggered by the RAAS to help raise blood pressure. The addition of an MRA attempts to target other parts of the RAAS system not covered by medications a patient is likely already taking.
Other treatment strategies include the following:
- Take medications exactly as described
- Limit intake of medications that can increase blood pressure (ibuprofen, for example).
- Follow a low-salt diet
- Reduce alcohol consumption