Resistant Hypertension
Assessment of high blood pressure that does not respond adequately to medication.
Areas of Expertise
Hypertension Diagnosis and Treatment in İzmir
Hypertension has been at the centre of Prof. Dr. İstemihan Tengiz's 29-year career. He is President of the Turkish Society for the Fight Against Hypertension and founding director of the only ESH-accredited Hypertension Excellence Centre in the Aegean region. He served on the World Hypertension League (WHL) board from 2011-2014 and chaired the organising committee of the World Hypertension Congress held in Istanbul in 2013.
What is hypertension and how is it diagnosed?
Hypertension means the pressure exerted by blood against the artery wall stays persistently high. According to European Society of Cardiology and European Society of Hypertension guidelines, office readings of 140/90 mmHg or above, measured with proper technique and repeated on separate days, support a diagnosis of hypertension. A single high reading is not diagnostic; anxiety, pain, coffee or smoking can raise blood pressure temporarily.
Out-of-office measurement is decisive in confirming the diagnosis. On 24-hour ambulatory monitoring, a daytime average above 135/85 mmHg or a full-day average above 130/80 mmHg is considered significant, as is a home average above 135/85 mmHg. These measurements are the only way to distinguish white-coat hypertension, which rises only in the clinic, from masked hypertension, which looks normal in the clinic but is elevated in daily life.
Why does it progress silently?
In most patients hypertension causes no symptoms for years. Headache, nosebleeds or neck stiffness occur only in some people and do not reliably track the level of blood pressure. As a result, high blood pressure is often discovered during a routine measurement, or only after a complication such as heart attack, stroke or kidney failure has already occurred.
The absence of symptoms does not mean the condition is harmless. Sustained high pressure thickens the heart muscle, stiffens the arterial wall and damages the filtering units of the kidney and the small vessels of the retina. Early diagnosis and regular follow-up can prevent most of this damage.
Which tests are performed?
The initial assessment includes blood pressure measurement in both arms, examination of the heart and lungs, and listening for bruits over the neck and abdominal vessels. Baseline tests then look for target organ damage and accompanying risk: ECG, echocardiography, creatinine and estimated glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio, potassium and sodium, fasting glucose, HbA1c, lipid profile and thyroid function.
Pulse wave velocity and central aortic pressure can be measured to quantify arterial stiffness objectively. Fundoscopic examination gives information about the duration and severity of disease through changes in the retinal vessels. The purpose of these tests is not only to establish the diagnosis but to decide how tightly the treatment target should be set.
Screening for secondary hypertension
In most patients no single cause is found; this is called primary or essential hypertension. In roughly one in ten patients, however, there is an underlying and treatable cause. The most common are primary aldosteronism, obstructive sleep apnoea, renal artery stenosis, chronic kidney disease, thyroid disorders and phaeochromocytoma. Painkillers, corticosteroids, nasal decongestants, oral contraceptives and certain herbal products can also raise blood pressure.
A search for a secondary cause is particularly warranted when hypertension starts before the age of 30, when previously controlled pressure suddenly worsens, when three or more drugs fail to reach target, when potassium is unexplainedly low, when kidney function deteriorates, or when there are episodes of abrupt surges.
Resistant hypertension and renal denervation
Resistant hypertension is defined as blood pressure that remains above 140/90 mmHg despite appropriate doses of three drugs from different classes, one of which is a diuretic. Before this diagnosis is made, causes of pseudo-resistance must be excluded: incorrect cuff size, poor measurement technique, irregular medication use, excessive salt intake and the white-coat effect. Ambulatory monitoring is mandatory to confirm true resistance.
In genuinely resistant cases, adding spironolactone is often effective. In selected patients who still do not respond, renal denervation — catheter-based quieting of the overactive sympathetic nerve endings around the renal arteries — may be considered. Current European guidelines position it as a complementary option to be used in experienced centres through shared decision-making with the patient; it does not replace drug therapy.
Lifestyle: the half of treatment that is not a drug
Reducing daily salt intake below 5 grams (about one teaspoon) can by itself produce a meaningful fall in systolic pressure. Most dietary salt comes not from the salt shaker but from bread, tomato paste, pickles, processed meats, instant soups and cheese. A DASH-style diet rich in vegetables, fruit, whole grains and low-fat dairy, together with weight loss and limited alcohol, is an inseparable part of treatment.
At least 150 minutes per week of moderate-intensity aerobic activity such as walking, swimming or cycling is recommended. Quitting smoking may not lower blood pressure dramatically on its own, but it is the single intervention that reduces cardiovascular risk fastest. In patients with sleep apnoea, treating the apnoea can be decisive for controlling resistant hypertension.
What does an ESH Hypertension Excellence Centre mean?
The European Society of Hypertension (ESH) accredits centres meeting defined criteria as Hypertension Excellence Centres. Accreditation requires standards-compliant measurement infrastructure, ambulatory and home monitoring capability, the ability to assess target organ damage, in-house investigation of secondary hypertension, multidisciplinary teamwork and continuous scientific output.
Prof. Dr. İstemihan Tengiz is the founding director of the only ESH-accredited Hypertension Excellence Centre in the Aegean region. The accreditation certificate was presented in 2022 by the then ESH President, Prof. Dr. Guido Grassi.
Procedures Performed
Renal Denervation (RDN)
Catheter-based ablation of sympathetic nerves around the renal arteries.
Ambulatory Blood Pressure Monitoring
24-hour recording of blood pressure and evaluation of its circadian rhythm.
Hypertension Excellence Centre
Holistic hypertension management with a multidisciplinary team.
Target Organ Damage Follow-up
Protecting the heart, kidneys, eyes and brain from hypertension.
Frequently Asked Questions
What should my blood pressure be?
For most adults the office target is around 130/80 mmHg, and on treatment systolic pressure is generally aimed at 120-129 mmHg. Targets are kept more flexible in patients over 80, in frail individuals and in advanced kidney disease. Your physician sets your target according to your accompanying conditions.
Is blood pressure medication lifelong?
In primary hypertension treatment is usually continuous, because the drug does not remove the disease — it keeps the pressure controlled. That said, substantial weight loss, salt restriction and regular exercise can allow the number of drugs or the dose to be reduced, and if a secondary cause is found and treated, medication may be stopped altogether. Stopping on your own lets blood pressure rise again silently.
How do I measure blood pressure correctly at home?
Sit quietly for 5 minutes beforehand and avoid coffee, smoking and exercise for the previous 30 minutes. Sit with your back supported, feet flat on the floor and your arm supported at heart level. Use a validated upper-arm device with a cuff that fits your arm circumference; wrist devices are less reliable. Take two readings a minute apart, twice a day — in the morning before medication and in the evening — record them and bring the log to your appointment.
What is resistant hypertension?
It is blood pressure that stays above 140/90 mmHg despite appropriate doses of three drug classes, one of them a diuretic. Before the diagnosis is made, adherence, measurement technique, cuff size and the white-coat effect must all be assessed, and the finding confirmed with 24-hour ambulatory monitoring.
Who is renal denervation suitable for?
It is considered in selected patients with true resistant hypertension confirmed by ambulatory monitoring, in whom secondary causes have been excluded and who either fail to reach target despite medication or cannot tolerate their drugs because of side effects. The decision should be made together with the patient in an experienced centre. It is not suitable for everyone and does not mean stopping existing medication.
When should I go to the emergency department?
If your blood pressure is above 180/120 mmHg and you have chest pain, severe breathlessness, slurred speech, one-sided weakness, loss of vision, severe headache or confusion, go to an emergency department without delay. This is called a hypertensive emergency and requires in-hospital treatment.
Content reviewed by Prof. Dr. İstemihan Tengiz. Last reviewed:
The information on this page is for general information only and is not a substitute for medical advice. Please consult your physician about your symptoms.