Hypertension Pathophysiology

Definition and Classification

• Hypertension: a chronic medical condition characterized by elevated blood pressure (BP) ≥ 140/90 mmHg
• Classified into:
  • Primary (essential) hypertension: no identifiable cause (90-95% of cases)
  • Secondary hypertension: underlying medical condition or medication-induced (5-10% of cases)

Pathophysiology

• Increased peripheral resistance and/or cardiac output lead to elevated BP
• Factors contributing to hypertension:
  • Genetics
  • Lifestyle (e.g., physical inactivity, obesity, smoking)
  • Diet (e.g., high sodium, low potassium)
  • Renal disease
  • Hormonal imbalances (e.g., aldosterone, cortisol)

Risk Factors and Complications

• Risk factors:
  • Age > 45 years
  • Family history
  • Obesity
  • Physical inactivity
  • Smoking
  • High sodium intake
  • Low potassium intake
• Complications:
  • Cardiovascular disease (e.g., heart failure, myocardial infarction)
  • Stroke
  • Chronic kidney disease
  • Retinopathy
  • Cognitive impairment

Antihypertensive Drugs

• Classes:
  1. Diuretics: increase urine production, reduce sodium reabsorption
     • Thiazide diuretics (e.g., hydrochlorothiazide)
     • Loop diuretics (e.g., furosemide)
  2. Beta blockers: reduce heart rate and cardiac output
     • Non-selective (e.g., propranolol)
     • Selective (e.g., metoprolol)
  3. Angiotensin-converting enzyme (ACE) inhibitors: block angiotensin II production
     • Captopril
     • Enalapril
  4. Angiotensin receptor blockers (ARBs): block angiotensin II receptors
     • Losartan
     • Valsartan
  5. Calcium channel blockers: relax blood vessels, reduce calcium influx
     • Dihydropyridines (e.g., amlodipine)
     • Non-dihydropyridines (e.g., verapamil)
  6. Alpha blockers: relax blood vessels, reduce peripheral resistance
     • Prazosin
     • Doxazosin
  7. Direct renin inhibitors: reduce renin production
     • Aliskiren
  8. Vasodilators: directly relax blood vessels
     • Hydralazine
     • Minoxidil

Treatment Guidelines

• Lifestyle modifications:
  • Dietary changes (e.g., DASH diet)
  • Weight loss
  • Increased physical activity
  • Smoking cessation
• Pharmacological treatment:
  • Monotherapy or combination therapy
  • Stepwise approach: start with low-dose, single drug, and gradually increase or add drugs as needed
  • Individualize treatment based on patient characteristics, comorbidities, and response to therapy

Definition and Classification

• Hypertension is a chronic medical condition characterized by elevated blood pressure (BP) ≥ 140/90 mmHg
• Primary (essential) hypertension has no identifiable cause and accounts for 90-95% of cases
• Secondary hypertension is caused by an underlying medical condition or medication and accounts for 5-10% of cases

Pathophysiology

• Increased peripheral resistance and/or cardiac output lead to elevated BP
• Genetic factors contribute to hypertension
• Lifestyle factors contributing to hypertension include physical inactivity, obesity, and smoking
• Diet-related factors include high sodium and low potassium intake
• Renal disease and hormonal imbalances (e.g., aldosterone, cortisol) also contribute to hypertension

Risk Factors and Complications

• Risk factors for hypertension include age > 45 years, family history, obesity, physical inactivity, smoking, high sodium intake, and low potassium intake
• Cardiovascular disease, stroke, chronic kidney disease, retinopathy, and cognitive impairment are potential complications of hypertension

Antihypertensive Drugs

• Diuretics increase urine production and reduce sodium reabsorption
• Beta blockers reduce heart rate and cardiac output
• Angiotensin-converting enzyme (ACE) inhibitors block angiotensin II production
• Angiotensin receptor blockers (ARBs) block angiotensin II receptors
• Calcium channel blockers relax blood vessels and reduce calcium influx
• Alpha blockers relax blood vessels and reduce peripheral resistance
• Direct renin inhibitors reduce renin production
• Vasodilators directly relax blood vessels

Treatment Guidelines

• Lifestyle modifications for hypertension include dietary changes, weight loss, increased physical activity, and smoking cessation
• Pharmacological treatment may involve monotherapy or combination therapy
• A stepwise approach to pharmacological treatment involves starting with low-dose, single drug, and gradually increasing or adding drugs as needed
• Treatment should be individualized based on patient characteristics, comorbidities, and response to therapy