Hypertension Management Quiz

Hypertension

• Definition: Raised arterial blood pressure above "normal"
• Classification of Blood Pressure for Adults Age 18 and Older:
  • Optimal: Systolic <120 and Diastolic <80
  • Normal: Systolic <130 and Diastolic <85
  • High-normal: Systolic 130-139 or Diastolic 85-89
  • Hypertension Stage 1: Systolic 140-159 or Diastolic 90-99
  • Hypertension Stage 2: Systolic 160-179 or Diastolic 100-109
  • Hypertension Stage 3: Systolic ≥180 or Diastolic ≥110
• Current Criteria for Adults:
  • Systolic > 140 mm Hg and/or Diastolic > 90 mm Hg
  • Prevalence: About 25% of the US population
  • Incidence increases with age
• Prevalence of Hypertension in the US (1988-1991):
  • The percentage of the US population with hypertension increases with age.

Types of Hypertension

• Primary ("Essential"):
  • Unknown cause
  • Accounts for 90% of cases
  • Drug therapy is the main course of treatment for this type
• Secondary:
  • Identifiable cause
  • Accounts for 10% of cases of Hypertension
  • Examples include renal vascular disease, primary and secondary aldosteronism, pheochromocytoma, and drugs (e.g., oral contraceptives, sympathomimetics, and drugs of abuse)

Why Reduce High Blood Pressure?

• Slow or interrupt progressive tissue and organ damage to:
  • Brain
  • Eyes
  • Kidneys
  • Heart
• Prolongs life

Treatment Rationale

• Long-term goal: Reduce mortality due to hypertension-induced disease.
  • Examples of hypertension-induced diseases:
    • Stroke
    • Congestive heart failure
    • Coronary artery disease
    • Nephropathy
    • Peripheral artery disease
    • Retinopathy

Major Risk Factors That Increase Mortality in Hypertension

• Smoking
• Dyslipidemias
• Diabetes Mellitus
• Age > 60
• Gender: Men, Postmenopausal women
• Family history

Current Problems

• Awareness issues due to lack of symptoms
• Treatment problems (inappropriate prescribing)
• Patient noncompliance (10% stop taking medication)
• Treatment complexity

Non-Pharmacological Interventions

• Diet:
  • Reduction of sodium intake
  • Caloric restriction for obese patients
  • Restriction of cholesterol and saturated fat intake.
• Stress reduction
• Regular aerobic exercise
• Weight reduction (if required)
• Control of other risk factors (blood lipids, smoking)

Physiological Mechanisms (controlling blood pressure)

• Blood Pressure = Cardiac Output x Total Peripheral Resistance.
• Cardiac output: Heart rate x stroke volume.
• Reflex control (Baroreceptor mechanism): Short-term regulation of blood pressure by pressure sensing areas throughout the CV system. Minute by minute control
• Renin-angiotensin system: Longer-term regulation of blood pressure. Acting over weeks and months.

Medications Used to Treat Hypertension

• Adrenergic agents (beta- and alpha-blockers)
• Angiotensin-converting enzyme (ACE) inhibitors
• Angiotensin II receptor blockers (ARBs)
• Calcium channel blockers
• Diuretics
• Vasodilators

Adrenoceptor Antagonists

• Alpha blockers:
  • Non-selective (e.g., Phenoxybenzamine, Phentolamine)- Block both alpha-1 and alpha-2 receptors.
  • Selective (e.g., Prazosin, Terazosin, Doxazosin) - selectively block alpha-1 receptors. Side effect of postural hypotension.
• Beta blockers selective and non-selective
  • Non-selective (e.g., Propranolol, Timolol) - block both beta-1 and beta-2 receptors.
  • Cardioselective (e.g., Metoprolol, Atenolol) - block primarily beta-1 receptors.
  • Intrinsic sympathomimetic activity (ISA)
• Beta blockers side effects: CNS effects, increased plasma triglycerides and decreased HDL, nausea, diarrhea, vomiting. Withdrawal syndrome. Beta blocker contraindications: unstable diabetes, and bronchospastic diseases

Central Nervous System Sympatholytics

• Clonidine
• Methyldopa
• Guanabenz
• Guanfacine

Clinically Significant Information: Clonidine, Methyldopa

• Clonidine: Full agonist at alpha-2 receptors, partial agonist at alpha-1 receptors. Acts centrally, lowering sympathetic outflow and potentially reducing postural hypotension. Short half-life. Available as transdermal patch for increased compliance. Side effects: sedation, dry mouth, and withdrawal syndrome.
• Methyldopa: Acts in the brain to lower BP, also appears to lower TPVR more than CO. Side effects: fever (mimics sepsis), dry mouth, and sedation.

Calcium Channel Blockers

• Dihydropyridines (e.g., Nifedipine, Amlodipine, Felodipine, Isradipine) - primarily affect arterioles.
• Non-dihydropyridines (e.g., Verapamil, Diltiazem) - primarily affect the heart.

Vasodilators

• Hydralazine
• Minoxidil
• Diazoxide
• Nitroprusside

ACE Inhibitors

• Reduces angiotensin II levels, vasoconstrictor effects, and aldosterone levels
• Blocks the breakdown of bradykinin (a potent vasodilator)
• Examples: Captopril and Enalapril. Hypotensive actions
• Side effects: dry, non-productive cough, severe hypotension, acute renal failure, hyperkalemia
• Contraindications: pregnancy

Angiotensin Receptor Blockers (ARBs)

• Block angiotensin type 1 receptors
• Have no effect on bradykinin metabolism
• Possibly reduced cough and angioedema, contraindicated in pregnancy
• Examples: Losartan and Valsartan

Thiazide Diuretics

• Prevent sodium reabsorption in the nephrons, potentially lowering BP.
• Decreases blood volume and CO.
• Examples: Hydrochlorothiazide and Chlorothiazide.
• Often used in combination with other antihypertensives

Potassium-Sparing Diuretics

• Examples: Spironolactone and Triamterene
• Aldosterone antagonist (Spironolactone only)
• Potentially combined with thiazides.

Loop Diuretics

• Examples: Furosemide, Ethacrynic acid, and Torsemide
• Used in heart failure and renal failure. Continuous BP lowering effects

Drug Therapy and Diagnosis

• Lifelong disease with few symptoms, often need drugs taken daily.
• Diagnosis should not be made from a single blood pressure reading but from repeated readings, and consideration of a complete medical history.
• Essential Information for selection of drug therapy: Presence of other diseases, socioeconomic status, expected compliance, level of BP, presence of end-organ damage, age, sex, and race.
• Need initial monotherapy, and may progress to multi drug therapy. Initial choice includes diuretics, ACE inhibitors or ARBs, calcium channel antagonists, and beta blockers.
• Rationale for Multi-drug therapy: Additive effects, enhanced blood pressure lowering, and reduced side effects.
• Rationale for combination drug therapies: Avoid giving two drugs with similar mechanisms and combine drugs to reduce reflex responses or potentially treat co-morbidities.
• Hypertensive Emergencies: sudden, severe elevation of BP. Use in critically ill patients. Examples: Nitroprusside, Labetalol, and Nicardipine.