Do You Know White Coat Hypertension?
White coat hypertension is also known as clinical isolated or consultation hypertension. The person who suffers from it presents blood pressure values higher than normal parameters when the measurement is performed in a clinical environment (consultation, health centers, hospitals, etc.).
However, when blood pressure is measured outside of the clinical environment, the values return to their normalcy. Although white coat hypertension has been recognized as a pathology for several years, some aspects are still unclear. But before we deal with this point, let’s explore some key concepts to better understand the phenomenon of white coat hypertension.
What is blood pressure?
Blood pressure is the force of blood against the wall of the arteries. This pressure is essential for blood to circulate through the blood vessels and deliver oxygen and nutrients to all organs in the body for them to function properly.
Blood pressure has two components:
- Systolic blood pressure: this corresponds to the maximum blood pressure value during systole (when the heart contracts). It refers to the effect of pressure exerted by blood ejected from the heart on the wall of the vessels.
- Diastolic blood pressure: this corresponds to the minimum blood pressure value when the heart is in a state of diastole or between heartbeats. It basically depends on the peripheral vascular resistance.
Blood pressure abnormalities
Two abnormalities or dysfunctions in blood pressure can occur:
- High blood pressure: it refers to the increase in blood pressure, whether it is systolic pressure or diastolic pressure. Hypertension, along with high cholesterol and smoking, is one of the three most important and modifiable cardiovascular risk factors.
- Arterial hypotension: it supposes a drop in arterial pressure, below normal limits. It normally manifests itself through fatigue and nausea.
White coat hypertension
As we said earlier, white coat hypertension occurs in some people when they go to hospitals or places related to the world of health, such as medical consultations.
We can define white coat hypertension as a warning reaction when the patient is in the presence of a doctor. This alert reaction is a complex and stereotypical response to a potentially threatening emotional stimulus. This reaction is characterized by an increase in blood pressure and heart rate when the doctor prepares to take a patient’s blood pressure. In other words, it is caused by the presence of the doctor during the measurement.
It is curious to see that if the person measuring the blood pressure is a friend, a relative or the patient himself, this warning reaction does not occur. Nurses can have the same effect, but to a lesser extent. The place where the blood pressure is taken also influences the appearance of white coat hypertension, as we have seen before.
What are the criteria for diagnosing white coat hypertension?
The European Society of Cardiology (ESC) has suggested the following diagnostic criteria for managing high blood pressure:
- Blood pressure values greater than 140/90 mmHg and measured during three different consultations.
- At least two measurements outside of a consulting room with blood pressure below 140/90 mmHg.
- No damage to organs.
- Average ABPM-day less than 135/85 mmHg. ABPM refers to ambulatory blood pressure monitoring.
What characteristics do patients with white coat hypertension have?
Patients with a tendency to suffer from white coat hypertension have the following characteristics:
- Blood pressure in consultation from 140/90 mmHg to 159/99 mmHg
- Female
- Non smokers
- Recently diagnosed high blood pressure
- Absence of left ventricular hypertrophy. Left ventricular hypertrophy refers to when the heart muscle grows, when the walls of the heart are thicker. Usually, it is the “consequence” of high blood pressure.
The heart of a patient with hypertension has to “pump” the blood with more effort because it circulates at a higher pressure. If this lasts over time (usually years), the heart muscle must “grow” (hypertrophy) so that it can pump blood more forcefully with each beat.
Why does white coat hypertension and the white coat effect occur?
Until now, no mechanism has clearly been identified to explain the cause of this phenomenon. However, we have found several proofs that we will now present to you:
Increased blood pressure in a clinical setting due to an alert reaction
We all suffer from an increase in blood pressure and heart rate in the face of a stimulus that we perceive as threatening (stressful). For people suffering from the white coat effect, this threatening or stressful stimulus would be the clinical context: when exposed to this setting, they would feel the physiological changes characteristic of a stress response. Thus, this hypertension would not be caused by cholesterol or another physiological cause but by stress itself.
This effect is therefore the result of a conditioned response to the clinical or hospital environment and not to the stimulus of the white coat. We understand by conditioned response a reaction or a learned reflected response to a stimulus. It receives the name of “conditioned” because it appears after the condition of learning, of the experience of the association of stimuli.
The salivating response for Pavlov’s famous dog is called conditioned but only when the dog has learned to display it in the face of a stimulus that did not provoke it in a natural way, such as the sound of the bell. He has this answer precisely because he has experienced its association or its temporal connection with the presence of the food in the mouth, which indeed provokes this answer in a natural way.
Conditioned responses are manifested by the body to what are called conditioned stimuli. At the level of the subject that interests us, the conditioned stimulus would be the clinical or hospital environment and not the white coat. The answer would be an increase in the activity of the sympathetic autonomic nervous system and a decrease in the activity of the parasympathetic autonomic nervous system.
The sympathetic autonomic nervous system is the one that takes care of the symptoms of nervousness, stress, etc. On the other hand, the parasympathetic autonomic nervous system does just the opposite. It is responsible for the feelings of tranquility and relaxation.
Thus, in white coat hypertension, there is increased activity of the sympathetic autonomic nervous system, which increases heart rate, blood pressure and causes tachycardia. However, the evidence indicates that the increase in heart rate is specially created by the reduced activation of the parasympathetic system.
The effect of the white coat vs hypertension of the white coat
The terms “white coat effect” and “white coat hypertension” are mistakenly used synonymously. The white coat effect refers to the transient rise in blood pressure that occurs as a warning reaction. This warning reaction is mainly caused by the clinical environment.
In contrast, with white coat hypertension, we are referring to the patient clinically suffering from hypertension in a medical consultation. In addition, the blood pressure values of this patient are maintained at normal ranges during daily activities. The white coat effect is not related to the level of “basic blood pressure” or outside the medical environment and may occur in patients with or without high blood pressure.
As we have seen, white coat hypertension is primarily generated and modulated by psychological factors. The person experiences an increase in blood pressure and heart rate when faced with a conditioned stimulus, as can the hospital or clinical environment. In this way, the treatment should also be psychological.
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