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What is arterial pressure?
The circulatory system of the human body consists of the heart, which acts as a pump, and the arteries and veins that form the network through which blood circulates, carrying oxygen and nutrients to the brain and the rest of the body. As blood circulates in the arteries, it exerts pressure on the walls of the arteries, similar to all fluids circulating in a network of tubes. Some pressure is necessary for the blood to circulate. This pressure is called arterial pressure and varies throughout the day and night. It is normal for it to increase during physical activity or mental stress and decrease in conditions of rest, relaxation, or during sleep.
What is arterial hypertension?
Hypertension refers to high blood pressure (BP). Normally, the arterial pressure in adults should not exceed 140/90 mmHg, but ideally, in home measurements, it should be below 135/85 mmHg. The first and larger value refers to systolic arterial pressure (SAP), while the second is diastolic arterial pressure (DAP).
It is important to note that we do not have hypertension when we occasionally and justifiably have increased blood pressure, such as during intense physical exercise or stress, but when systematically and unjustifiably increased arterial pressure is observed. This forces the heart to work harder to circulate blood in the arteries. If not addressed in a timely manner, it progressively transforms the arteries from flexible and elastic tubes into rigid and non-compliant ones, prone to injury and the development of atherosclerotic plaques and narrowings. This significantly increases the risk of coronary artery disease, heart attacks, stroke, kidney dysfunction, eye damage, and cognitive impairment-dementia.
Hypertension is usually asymptomatic, especially in its early stages. If left undiagnosed or untreated successfully (which almost always requires medical advice), hypertension leads to damage in specific organs of the body called "target organs," including the heart, brain, kidneys, eyes, carotid arteries, aorta, and arteries in the lower extremities.
According to the "Hippokratio Hellenic Hypertension Study (3H study)," approximately 30%-45% of hypertensive Greeks have left ventricular hypertrophy, 8%-15% have microalbuminuria, and 7%-10% have impaired kidney function.
High blood pressure is responsible for 50% of cardiovascular diseases and 13% of all deaths worldwide.
HEART: Hypertrophy, angina, heart attack, atrial fibrillation, other arrhythmias, heart failure.
BRAIN: Ischemic stroke, rarely hemorrhagic stroke in young individuals, vascular dementia.
EYES: Hypertensive retinopathy.
KIDNEYS: Proteinuria, kidney failure.
CAROTID ARTERIES: Narrowing due to atherosclerotic damage.
AORTA: Aneurysm-rupture of an aneurysm.
LOWER EXTREMITIES: Peripheral arterial disease - intermittent claudication.
Etiology of arterial hypertension:
Hypertension is a multifactorial disease. This means that its occurrence is influenced by genetic factors (heritability), excessive salt consumption, and other dietary factors, body weight, lack of physical exercise, the presence of stress, and in this case, it is characterized as Essential Hypertension. Rarely (in 5-15% of cases), it is due to the presence of another underlying medical condition (Secondary Hypertension).
Classification of arterial hypertension:
Optimal: Systolic Blood Pressure (SBP) < 120 mmHg and Diastolic Blood Pressure (DBP) < 80 mmHg.
Normal: SBP 120-129 mmHg and/or DBP 80-84 mmHg.
High-Normal: SBP 130-139 mmHg and/or DBP 85-89 mmHg.
Hypertension Stage I: SBP 140-159 mmHg and/or DBP 90-99 mmHg.
Hypertension Stage II: SBP 160-179 mmHg and/or DBP 100-109 mmHg.
Hypertension Stage III: SBP ≥ 180 mmHg and/or DBP ≥ 110 mmHg.
Isolated Systolic Hypertension: SBP ≥ 140 mmHg and DBP < 90 mmHg.
Other types and terms of hypertension
White-coat hypertension
White-coat hypertension is defined as an elevated office untreated BP, but is normal when measured by ABPM, HBPM, or both [4]. The difference between the higher office and the lower out-of-office BP is referred to as the “white coat effect”, and is believed to reflect mainly the pressor response to an alerting reaction elicited by office BP measurements by a doctor or a nurse, although other factors are probably also involved [5]. It can account for up to 30 to 40% of people (and >50% in the very old) with an elevated office BP. It is more common with increasing age, in women, and in non-smokers. Its prevalence is lower in patients with HMOD, when office BP is based on repeated measurements, or when a doctor is not involved in the BP measurement. A significant white-coat effect can be seen at all grades of hypertension (including resistant hypertension), but the prevalence of white-coat hypertension is greatest in grade 1 hypertension.
The white-coat effect is used to describe the difference between an elevated office BP (treated or untreated) and a lower home or ambulatory BP in both untreated and treated patients.
Masked hypertension:
Masked hypertension refers to untreated patients in whom BP is normal in the office but is elevated when measured by HBPM or ABPM [6]. It can be found in approximately 15% of patients with a normal office BP. The prevalence is greater in younger people, males, smokers, and those with higher levels of physical activity, alcohol consumption, anxiety, and job stress. Obesity, diabetes, chronic kidney disease (CKD), family history of hypertension, and high–normal office BP are also associated with an increased prevalence of masked hypertension. It is associated with dyslipidaemia and dysglycaemia, HMOD [7], adrenergic activation, and increased risk of developing diabetes, and sustained hypertension [6].
Resistant hypertension and pseudo-resistant hypertension:
Hypertension is defined as resistant to treatment when the recommended treatment strategy fails to lower office SBP and DBP values to <140 mmHg and/or <90 mmHg, respectively, and the inadequate control of BP is confirmed by ABPM or HBPM in patients whose adherence to therapy has been confirmed. Prevalence studies of resistant hypertension have been limited by variation in the definition used; the reported prevalence rates range from 5–30% in patients with treated hypertension. After applying a strict definition and having excluded causes of pseudo-resistant hypertension, the true prevalence of resistant hypertension is likely to be <10% of treated patients. Patients with resistant hypertension are at higher risk of HMOD, CKD, and premature CV events [8].
Possible causes of pseudo-resistant hypertension are:
- Poor adherence to prescribed medicines
- White-coat phenomenon
- Poor office BP measurement technique
- Marked brachial artery calcification
- Clinician inertia
Secondary hypertension:
Secondary hypertension is hypertension due to an identifiable cause, which may be treatable with an intervention specific to the cause. A high index of suspicion and early detection of secondary causes of hypertension are important because interventions may be curative, especially in younger patients; however, interventions later in life are less likely to be curative (i.e., removing the need for antihypertensive medication) because longstanding hypertension results in vascular and other organ damage that sustains the elevated BP. Nevertheless, intervention is still important because it will often result in much better BP control with less medication.
The prevalence of secondary hypertension is reported to be 5–15% [9] of people with hypertension. Screening all hypertensive patients for secondary hypertension is not feasible or cost-effective; it should be confined to some general patient characteristics that suggest those more likely to have secondary hypertension and in whom screening should be considered after confirming that BP is elevated with ABPM.
Treatment of arterial hypertension:
Arterial hypertension must always be treated to prevent target organ damage regardless of the presence or absence of symptoms.
This management includes a series of measures aiming for the blood pressure to be <130/80mmHg but usually not below 115/65 mmHg:
- Low-salt diet.
- Weight reduction.
- Aerobic exercise.
- Smoking cessation.
- Medication therapy.
- Managing stress-inducing daily situations.
- Healthy diet and limiting alcohol intake.
The regulation of lipid levels and blood glucose also plays a significant role in the management of hypertensive patients.