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Hypertension for ABIM

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Hypertension for the American Board of Internal Medicine Exam
Overview of Hypertension
Hypertension, defined as persistently elevated blood pressure (BP), is a major risk factor for cardiovascular disease, stroke, chronic kidney disease, and other complications. For adults, the American College of Cardiology (ACC) and the American Heart Association (AHA) define hypertension as a systolic BP (SBP) of ≥130 mm Hg or a diastolic BP (DBP) of ≥80 mm Hg.
arterial blood pressure
Classification of Hypertension
  • Normal BP: SBP <120 mm Hg and DBP <80 mm Hg
  • Elevated BP: SBP 120–129 mm Hg and DBP <80 mm Hg
  • Stage 1 Hypertension: SBP 130–139 mm Hg or DBP 80–89 mm Hg
  • Stage 2 Hypertension: SBP ≥140 mm Hg or DBP ≥90 mm Hg
Types of Hypertension
Primary (Essential) Hypertension
  • Definition: Chronic elevation of BP with no identifiable cause, accounting for ~90% of hypertension cases.
  • Risk Factors:
    • Genetic: Family history.
    • Environmental: High sodium intake, sedentary lifestyle, obesity, and alcohol use.
    • Demographic: Increased age, male gender, African American race.
  • Pathophysiology: Involves complex interactions between genetic, environmental, and neurohormonal factors affecting vascular tone, sodium handling, and cardiac output.
Secondary Hypertension
  • Definition: Hypertension due to an identifiable underlying condition, representing ~10% of cases.
  • Common Causes:
    • Renal Parenchymal Disease: Most common cause of secondary hypertension, due to kidney’s role in BP regulation.
    • Renovascular Hypertension: Due to renal artery stenosis, often caused by atherosclerosis or fibromuscular dysplasia.
    • Endocrine Disorders: Includes primary hyperaldosteronism, pheochromocytoma, Cushing’s syndrome, and hyperthyroidism.
    • Obstructive Sleep Apnea (OSA): Linked to chronic sympathetic activation.
    • Medications: NSAIDs, oral contraceptives, decongestants, and corticosteroids.
Diagnosis
Blood Pressure Measurement
  • Office BP: Confirmed by two or more measurements on separate occasions. BP should be measured after the patient has been seated for at least five minutes, with the arm at heart level.
  • Home BP Monitoring: Recommended to confirm diagnosis in cases of white coat or masked hypertension.
  • Ambulatory BP Monitoring (ABPM): Gold standard for diagnosing white coat hypertension, masked hypertension, and nocturnal hypertension.
Diagnostic Workup
  • Basic Laboratory Tests:
    • Electrolytes, Creatinine, and Blood Urea Nitrogen (BUN): Assess renal function and possible electrolyte abnormalities.
    • Fasting Glucose and Lipid Panel: Screen for metabolic syndrome or diabetes, which are often comorbid with hypertension.
    • Urinalysis: To detect proteinuria or hematuria as indicators of renal disease.
    • Electrocardiogram (ECG): Assess for LV hypertrophy, which is a complication of longstanding hypertension.
  • Additional Testing for Secondary Hypertension:
    • Plasma Aldosterone and Renin Activity: Screening for primary hyperaldosteronism in cases of unexplained hypokalemia.
    • 24-Hour Urine Metanephrines and Catecholamines: For suspected pheochromocytoma.
    • Renal Duplex Ultrasound or CT Angiography: To evaluate for renal artery stenosis in young patients or those with resistant hypertension.
Management
Lifestyle Modifications
  • Weight Loss: A reduction of 1 mm Hg per kilogram of weight loss has been observed.
  • Diet: The DASH diet (high in fruits, vegetables, whole grains, and low-fat dairy, with reduced saturated fat) lowers SBP by ~11 mm Hg in hypertensive patients.
  • Sodium Restriction: Aim for <1500 mg/day; a reduction to <2400 mg/day may also be beneficial.
  • Physical Activity: Recommended at 90–150 minutes of aerobic exercise per week, which can reduce SBP by 4–8 mm Hg.
  • Alcohol Moderation: Limit to ≤2 drinks per day for men and ≤1 drink per day for women.
Pharmacologic Therapy
  • Indications for Medication:
    • Stage 1 Hypertension: Initiate medication if the patient has clinical cardiovascular disease (CVD) or a 10-year atherosclerotic cardiovascular disease (ASCVD) risk ≥10%.
    • Stage 2 Hypertension: Initiate medication for all patients, regardless of ASCVD risk.
  • First-Line Agents:
    • Thiazide Diuretics: First-line for most patients; chlorthalidone is preferred due to its longer half-life and proven reduction in cardiovascular events.
    • ACE Inhibitors (ACEIs) and Angiotensin II Receptor Blockers (ARBs): Useful in patients with chronic kidney disease (CKD), diabetes, or heart failure; avoid combining ACEIs with ARBs.
    • Calcium Channel Blockers (CCBs): Effective in reducing stroke risk; particularly beneficial in African American and older adults.
    • Beta-Blockers: Not first-line for hypertension alone but indicated in patients with heart failure, post-myocardial infarction, or certain arrhythmias.
  • Second-Line and Adjunctive Agents:
    • Aldosterone Antagonists (e.g., Spironolactone): Effective for resistant hypertension and primary hyperaldosteronism.
    • Vasodilators (e.g., Hydralazine): Used for resistant cases but often combined with other medications due to reflex tachycardia and fluid retention.
    • Alpha-Blockers: Reserved for patients with concurrent benign prostatic hyperplasia.
Special Considerations
  • Resistant Hypertension: Defined as BP ≥130/80 mm Hg despite optimal doses of three antihypertensives, including a diuretic.
    • Workup: Consider secondary hypertension, especially primary hyperaldosteronism and renal artery stenosis.
    • Treatment: Addition of aldosterone antagonists, such as spironolactone, is often effective.
  • Hypertensive Emergency:
    • Defined by BP ≥180/120 mm Hg with end-organ damage (e.g., encephalopathy, acute kidney injury, myocardial ischemia).
    • Management: Requires IV antihypertensives (e.g., nitroprusside, labetalol, nicardipine) to reduce BP gradually, typically by no more than 25% within the first hour to avoid ischemic complications.
  • Hypertensive Urgency:
    • Elevated BP ≥180/120 mm Hg without end-organ damage.
    • Management: Oral antihypertensives to reduce BP over 24–48 hours, without the need for immediate, rapid reduction.
Complications
  • Cardiovascular: Coronary artery disease, heart failure, LV hypertrophy, and stroke.
  • Renal: Chronic kidney disease, nephrosclerosis.
  • Vascular: Aortic dissection, peripheral artery disease.
  • Ophthalmic: Hypertensive retinopathy, ranging from AV nicking to papilledema in malignant hypertension.
Key Points
  • Classification: Hypertension is defined as BP ≥130/80 mm Hg, with Stage 1 and Stage 2 categories guiding treatment.
  • Diagnosis: Accurate BP measurement and consideration of secondary causes are essential; confirm diagnosis with multiple readings.
  • Management:
    • Lifestyle Modifications: Key for all patients, particularly with the DASH diet, reduced sodium, and regular exercise.
    • Pharmacologic Therapy: First-line agents include thiazide diuretics, ACE inhibitors/ARBs, and CCBs.
    • Resistant Hypertension: Evaluate for secondary causes and consider aldosterone antagonists.
  • Complications: Hypertension is a major risk factor for cardiovascular disease, stroke, chronic kidney disease, and hypertensive retinopathy.
  • Emergencies:
    • Hypertensive Emergency: Requires IV antihypertensives and gradual BP reduction due to end-organ damage.
    • Hypertensive Urgency: Managed with oral antihypertensives, targeting BP reduction over 24–48 hours.

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