Causes of Hypertension

Causes of Hypertension

• Renal causes: Diabetic nephropathy, Pyelonephritis, Polycystic kidney, Analgesic nephropathy
• Renovascular causes: Renal artery stenosis, Endocrinal hypertension
• Endocrinal causes: Pituitary (Acromegaly), Thyroid (Hypothyroidism, Hyperthyroidism), Parathyroid (Hyperparathyroidism), Suprarenal gland (Conn's syndrome, Cushing's syndrome, Pheochromocytoma)
• CNS, Vascular, Iatrogenic causes: CNS (↑ intracranial tension, Medullary lesions), Vascular (Polyarteritis nodosa, Coarctation of aorta), Iatrogenic (Contraceptive pills, Cortisone, Catecholamines, Calcium, Cabenoxolone, Cyclosporine, NSAIDs, Erythropoeitin)
• Pregnancy: Preeclampsia/ eclampsia
• Blood: Polycythemia (hyperviscosity)
• Obstructive Sleep Apnea: Loud snoring, Witnessed apnea, Excessive daytime somnolence

Symptoms of Hypertension

• Asymptomatic in most cases (Silent Killer)
• May be discovered accidentally
• Headache (occipital), Chest pain, Nocturia, Nausea, vomiting, tinnitus, blurring of vision, epistaxis
• Symptoms of cause
• Symptoms of complications
• Signs of hypertension: BP > 140/90 mm Hg, Signs of cause, Signs of LV hypertrophy, Pulsating aortic area with dilated aorta
• Cardiac auscultation: ↑S1 (muscular component), ↑S2 (close or reversed splitting of S2), S3 gallop (LVF), S4 gallop (diastolic dysfunction), Ejection click, Soft ejection systolic murmur, Early diastolic murmur (dilated aortic root)

Definition and Staging of Hypertension

• Definition: Persistent elevation of arterial BP > 140/90 mm Hg
• Staging of office blood pressure: three stages

Types of Hypertension

• Primary (essential, idiopathic) hypertension: About 95% of cases, no known causes, starts between 35-55 years, family history is usually positive, predisposing factors: Genetic, obesity, stress, salt sensitivity, smoking
• Secondary (curable) hypertension: About 5% of cases, known underlying cause, starts before 25 and after 55 years, negative family history, rapidly progressive with early complications

Theories of Primary Hypertension

• Sympathetic overactivity
• Activation of renin-angiotensin aldosterone system
• Increased adrenal gland activity → ↑ aldosterone activity
• Hyperinsulinemia due to peripheral insulin resistance
• ↓ atrial natriuretic peptide (ANP)
• Baroreceptor re-seting
• Multifactorial theory: Strss → ↑ sympathetic → renal ischemia → ↑ renin → ↑ aldosterone → ↑ BP

Complications of Hypertension

• Target organs affected: Kidney (renal failure), Heart (LVH, heart failure), Brain (stroke or TIA), Eye (hypertensive retinopathy), Arteries (atherosclerosis, aortic dissection)
• Acute complications: Cerebral stroke, hypertensive encephalopathy, subarachnoid hemorrhage, acute pulmonary edema, dissecting aneurysm, acute coronary syndromes, acute renal failure, hypertensive crises

Investigations of Hypertension

• For etiology: as secondary hypertension
• For complications: Cardiac (ECG, CXR, ECHO), Cerebral (CT, MRI brain), Renal (urinalysis, renal function, renal imaging)

Measurement of BP

• Variables that may affect BP: Eating, Emotion, Exercise, Exposure to cold, Empty or full bladder, Smoking, Sympathomimetics (cold remedies)
• Blood Pressure Measurement: Sphygmomanometer, Systolic pressure = pressure when 1st sound is heard, Diastolic pressure = pressure when last sound is heard
• Blood Pressure Cuff Size: Small – children and small adults, Average, Large – overweight and large adults
• Types of sphygmomanometers: Mercury, Aneroid, Automatic (Electronic/Digital)