Essential Hypertension

Detailed Overview

Often termed the "silent killer," essential hypertension typically produces no symptoms until target organ damage occurs. It accounts for 90-95% of all hypertension cases. The condition is mediated by a complex interplay of genetic, environmental, and lifestyle factors leading to increased systemic vascular resistance and altered renal sodium handling. Lifelong management with lifestyle modifications and pharmacotherapy is required.

Epidemiology & Demographics

Affects nearly 46% of adults in the United States. Prevalence increases sharply with age. Higher prevalence and severity in African American populations. Lifetime risk for adults over 45 is 90%.

Etiological Mechanism

Idiopathic. It is a polygenic trait interacting with environmental exposures.

Primary Causes

No single distinct cause, but heavily influenced by high dietary sodium, obesity, insulin resistance, and sympathetic nervous system overactivity.

• Obesity: Central adiposity strongly correlates with increased BP via sympathetic activation and RAAS upregulation.
• High sodium diet: Intake > 3 g/day leads to fluid retention and vascular reactivity.
• Family history: Accounts for 30-60% of blood pressure variance.

Blood pressure is the product of cardiac output and systemic vascular resistance (SVR). In essential hypertension, SVR is uniformly elevated. This occurs due to 1) Sympathetic Nervous System overactivity causing peripheral vasoconstriction and tachycardia. 2) Overactivation of the Renin-Angiotensin-Aldosterone System (RAAS), where excess Angiotensin II causes direct vasoconstriction and Aldosterone drives renal sodium and water retention. 3) Endothelial dysfunction, characterized by an imbalance between vasodilators (nitric oxide) and vasoconstrictors (endothelin). 4) Defective renal pressure natriuresis, forcing the kidney to require higher systemic pressures to excrete a given sodium load. Chronically elevated pressure causes vascular remodeling (arteriolosclerosis), left ventricular hypertrophy, and glomerular damage.

Characteristic Clinical Presentation

• Usually asymptomatic: No symptoms in mild to moderate disease.
• Headache: Usually occipital, occurring in the morning (seen in severe hypertension).
• Dizziness or Palpitations: Non-specific symptoms prompting blood pressure check.

Physical Examination Signs

• S4 heart sound (due to left ventricular hypertrophy and stiffened ventricle).
• Hypertensive retinopathy changes: AV nicking, copper-wiring, or cotton-wool spots.
• Sustained elevated BP measurements (e.g., > 130/80 mmHg).

• Left Ventricular Hypertrophy (LVH): Heart muscle thickens against high afterload, leading to heart failure with preserved ejection fraction (HFpEF).
• Ischemic Stroke and Intracerebral Hemorrhage: Due to accelerated atherosclerosis and rupture of Charcot-Bouchard microaneurysms.
• Chronic Kidney Disease: Hypertensive nephrosclerosis leading to ESRD.

Diagnostic Criteria & Guidelines

Diagnosis requires properly measured seated blood pressure resting for 5 minutes, showing elevated BP on >= 2 distinct occasions. AHA/ACC 2017 criteria define hypertension as BP >= 130/80 mmHg. Out-of-office measurements (Ambulatory BP monitoring) are recommended to confirm diagnosis.

Differential Diagnosis

• Secondary hypertension (Renal artery stenosis, Primary hyperaldosteronism, Pheochromocytoma)
• White coat hypertension
• Obstructive Sleep Apnea (OSA) related hypertension

Laboratory Tests & Biomarkers

• Basic Metabolic Panel: To evaluate baseline renal function (Cr) and potassium (hypokalemia suggests primary hyperaldosteronism).
• Urinalysis: To check for proteinuria.
• ECG: May show LVH criteria (S wave in V1 + R wave in V5/V6 > 35 mm).

Imaging Modalities & Findings

• Echocardiogram: Not routine for diagnosis, but useful to assess for left ventricular hypertrophy and diastolic dysfunction.

• Elevated BP
  Systolic 120-129 AND diastolic < 80 mmHg.
• Stage 1 Hypertension
  Systolic 130-139 OR diastolic 80-89 mmHg.
• Stage 2 Hypertension
  Systolic >= 140 OR diastolic >= 90 mmHg.
• Hypertensive Crisis
  Systolic > 180 OR diastolic > 120 mmHg.

Second-Line & Adjunctive Therapy

Combination of two first-line agents from different classes (e.g., Amlodipine + Lisinopril). For resistant hypertension (BP uncontrolled on 3 drugs including a diuretic), add Spironolactone 25 mg PO daily.

Surgical & Procedural Management

N/A for essential hypertension. (Renal sympathetic denervation is experimental).

Recommended Lifestyle Changes

• DASH diet: Rich in fruits, vegetables, low-fat dairy; low in saturated fat.
• Sodium restriction: < 1500 mg/day optimal, < 2300 mg/day baseline.
• Aerobic physical activity: 90-150 min/week.
• Weight loss: Expect ~1 mmHg BP reduction for every 1 kg of weight loss.

Patient Counseling & Advice

Explain that they will likely feel no different when their BP is high vs. controlled, but taking medication daily prevents strokes and heart attacks years down the line.

Follow-Up & Monitoring Schedule

Recheck BP in 1 month after initiating or changing medication. Once at target (<130/80), monitor every 3-6 months. Annual check of serum creatinine, potassium, and lipids.

Preventive Strategies

Maintenance of normal body weight, regular exercise from a young age, and population-level reductions in dietary sodium.

Excellent with strict adherence to therapy. Untreated, it shortens life expectancy by 10-20 years, mostly through cardiovascular mortality.