Lecture on Hypertension

Introduction

• Hypertension is discussed as part of clinical medicine.
• Types of Hypertension:
  • Essential (Primary) Hypertension: ~90% of cases.
  • Secondary Hypertension: ~10% of cases.

Essential Hypertension

• Common in older individuals.
• Mechanism: Thickening of blood vessel walls reduces diameter, increasing systemic vascular resistance and thereby blood pressure.
• Causes:
  • Advanced age, smoking, diabetes.
  • Increased stress and obesity.
  • High sodium diet affecting renal function, increasing sodium and water retention, leading to increased blood pressure.

Secondary Hypertension

• Characteristics:
  • Often refractory to treatment with three or more antihypertensive drugs.

Causes:

1. Renal Causes
   • Chronic kidney disease, renal artery stenosis.
   • Activation of the renin-angiotensin-aldosterone system.
2. Endocrine Causes
   • Thyroid disorders (hyperthyroidism, hypothyroidism).
   • Adrenal disorders (hyperaldosteronism, Cushings, pheochromocytoma).
3. Neurological Causes
   • Increased intracranial pressure leading to Cushing's triad (bradycardia, hypertension, irregular respirations).
4. Aortic Diseases
   • Coarctation of the aorta causing differential blood pressures in limbs.
5. Pregnancy-Related
   • Preeclampsia and eclampsia.
6. Substances and Sleep Apnea
   • Drug-induced (cocaine, amphetamines).
   • Sympathetic activation in sleep apnea.

Diagnosis of Hypertension

• Measure blood pressure in both arms.
• Confirm diagnosis with at least two elevated readings across separate visits.
• Rule out: White coat hypertension using ambulatory monitoring.
• Hypertensive Crisis: Differentiate urgency (no organ damage) from emergency (with organ damage).

Treatment

• Lifestyle Modifications: Recommended for all, including weight loss, DASH diet, reduce sodium/alcohol intake.
• Medications:
  • Stage 1: Initiate antihypertensives if cardiovascular risk is high.
  • Stage 2: Begin antihypertensives immediately.
  • Options include ACE inhibitors, ARBs, thiazide diuretics, calcium channel blockers.
  • Consider comorbid conditions when choosing specific medications (e.g., beta blockers for post-MI, ACE inhibitors for CKD).

Hypertensive Crisis Management

• Urgency: Lower BP gradually with oral medications.
• Emergency: Lower BP carefully with IV medications, titrating to avoid rapid drops.

Complications of Hypertension

• Cardiovascular System: Left ventricular hypertrophy, heart failure, coronary artery disease, aortic dissection.
• Neurological System: Stroke, transient ischemic attacks, intracerebral or subarachnoid hemorrhage.
• Renal System: Chronic kidney disease, acute kidney injury.
• Retinopathy: Progressive stages leading to optic disc swelling.

Conclusion

• Understanding the underlying causes and mechanisms of hypertension is crucial for effective diagnosis and treatment.