Hypertension Overview

Hypertension

• Arterial blood pressure (BP) is the pressure in the arterial walls, measured in millimeters of mercury (mmHg).
• Systolic pressure is the peak pressure in arteries when blood is pumped during ventricular systole.
• Diastolic pressure is the lowest pressure in arteries when blood flows back into the vessels during ventricular diastole.
• Pulse pressure is the difference between systolic and diastolic pressure (normally 40 mmHg).

Hypertension: Definition

• Hypertension is persistent elevation in arterial blood pressure.
• A reading of more than 140/90 mmHg is considered hypertension.

Epidemiology of Hypertension

• Hypertension is a widespread condition contributing to significant morbidity and mortality, along with substantial direct and indirect costs.
• Globally, approximately 1 billion individuals are estimated to have hypertension.
• Approximately 7 million deaths annually are potentially linked to hypertension.

Classification of Blood Pressure (BP)

Etiology of Hypertension

• Primary (essential) hypertension: Cause unknown in most cases (~90% of patients). It is managed, but not cured.
• Secondary hypertension: A specific cause exists (e.g., underlying medical conditions). If the cause is identified, it can often be treated, and potentially cured.

Secondary Causes of Hypertension

• Chronic kidney disease
• Cushing syndrome
• Coarctation of the aorta
• Obstructive sleep apnea
• Parathyroid disease
• Pheochromocytoma
• Primary aldosteronism
• Renovascular disease
• Thyroid disease

Pathophysiology of Primary Hypertension

• The pathophysiology of primary hypertension is diverse, but fundamentally involves effects on both:
  • Cardiac output
  • Peripheral resistance
• Multiple factors are involved in essential hypertension development including:
  • Humoral factors (RAAS)
  • Vasodepressor mechanisms
  • Neuronal mechanisms
  • Abnormalities in sodium, calcium, and natriuretic hormones
• Most antihypertensive drugs work by impacting these mechanisms.

Diagnostic Considerations

• Hypertension is often called the "silent killer" because many individuals don't experience symptoms.
• Diagnosis requires multiple BP measurements across multiple visits.

Diagnostic Evaluation of BP

• Establishing BP levels.
• Identifying potential secondary causes.
• Assessing overall cardiovascular risk.
• Ruling out potential treatable causes.
• The evaluation includes:
  • Multiple BP measurements
  • Medical history review
  • Physical examination
  • Lab/instrumental investigations

Measuring Blood Pressure

• Diagnosis typically relies on multiple BP measurements taken over time.
• Techniques include mercury sphygmomanometers and non-invasive devices (e.g., oscillometric or automated devices).
• Office-based measurements form a key reference for treatment.

Recommendations for Measuring BP

• Patients should refrain from caffeine and nicotine for 30 minutes before measurement.
• Patients should be seated, with feet flat on the floor and back supported.
• Appropriate cuff size is critical.
• A quiet and private environment is essential.
• A 5-minute rest period precedes the measurement.

Ambulatory and Self-BP Monitoring

• Useful in suspected white-coat hypertension to differentiate from actual hypertension.
• Helpful in monitoring patients with suspected drug resistance, hypotensive symptoms, episodic hypertension, and/or autonomic dysfunction, and identifying "non-dippers."

Normal Upper Limit for BP

• Office-based: 140/90 mmHg
• ABPM (24-hour average): <130/80 mmHg
• Daytime (awake): <135/85 mmHg
• Nighttime/sleep: <120/70 mmHg
• Self-BP measurement: 135/85 mmHg

Hypertensive Crises

• Hypertensive crises involve severely elevated BP, typically >180/120 mmHg.
  • Emergencies: Accompanied by acute target organ damage.
  • Urgencies: High BP without acute target organ damage.

Cardiovascular Risk and Blood Pressure

• Risk of stroke, myocardial infarction, angina, heart failure, and kidney failure is directly correlated with BP.
• Higher BP is associated with a higher risk of cardiovascular disease, doubling with a 20/10mmHg increase).
• Even prehypertension increases CV risk.
• Treatment with antihypertensives significantly reduces CV risks.

Hypertension-Associated Complications

• Atherosclerosis in major blood vessels.
  • Coronary artery disease
  • Myocardial infarction
  • Chronic stable angina
  • Ischemic stroke
  • Transient ischemic attack
  • Peripheral arterial disease
  • Abdominal aortic aneurysm
• Other cardiovascular diseases
  • Left ventricular dysfunction (heart failure)
  • Chronic kidney disease

Risk Factors for Hypertension-Associated Complications

• Advanced age
• Smoking
• Obesity
• Physical inactivity
• Dyslipidemia
• Diabetes
• Kidney disease
• Microalbuminuria
• Lower estimated GFR

Benefits of Lowering BP

• Reduced rates of stroke, CAD events, vascular mortality, congestive heart failure (CHF), and left ventricular hypertrophy (LVH).

Goal Blood Pressure and Initial Drug Therapy

• Guidelines vary regarding target blood pressure and appropriate first-line medications based on patient characteristics.
• Factors such as age, comorbidities, and associated risk factors can influence treatment strategy.

Resistant Hypertension

• Defined as hypertension that remains uncontrolled despite use of three antihypertensive drugs (including a diuretic), at maximum tolerated doses.
• Several possible contributing causes including nonadherence, drug-interactions, and underlying conditions.

Diagnostic Algorithm for High Blood Pressure

• The algorithm outlines a process for diagnosis involving multiple BP readings across various settings.
• Decisions to initiate treatment, further testing, or referral are often based on this algorithm.

Clinical Evaluation (Cont'd)

• Once persistent hypertension is confirmed, an evaluation determines the extent of target organ damage, assesses overall cardiovascular risk, and rules out potentially curable causes.

Compelling Indications for Initial Hypertension Treatment.

• Heart failure
• Post-myocardial infarction
• Chronic kidney disease (CKD)
• Diabetes mellitus
• Coronary artery disease
• Recurrent stroke prevention
• Pregnancy