Hypertension is defined as blood pressure >140-90mmHg on 3 separate readings.
Hypertension has many causes and many complications. The majority of patients with hypertension are asymptomatic. This is why screening should be performed every 3 years.
Hypertension is the greatest risk factor for premature death and coronary artery disease. It causes 50% of vascular deaths (8 million per year). It is the most common cause of Stroke, Coronary Artery Disease, Peripheral Artery Disease, and End-Stage Renal Disease.
The etiology of hypertension is unknown in 95% of cases.
Definition of terms
| Term | Definition |
|---|---|
| White coat hypertension | Elevated clinical blood pressure. Normal ambulatory blood pressure monitoring (ABPM) < 135/85 mmHg on average per day |
| Masked hypertension | Normal clinical pressure. Elevated ambulatory blood pressure measurement (ABPM) > 135/85 on average per day. |
Causes of hypertension
| Category | Causes |
|---|---|
| Essential hypertension (primary or idiopathic – 95%) | Genetics and environmental influence |
| Cardiovascular | Coarctation of the aorta, polyarteritis nodosa, high intravascular volume, high cardiac output, rigid aorta |
| Endocrine | Adrenocortical hyperfunction (Cushing syndrome and hyperaldosteronism), pheochromocytoma, exogenous hormones (corticosteroids and estrogen), pregnancy-induced (preeclampsia and eclampsia), monoamine oxidase inhibitors, tyramine-containing foods (chocolate and cheese), hypercalcemia, acromegaly |
| Renal | Acute glomerulonephritis, chronic renal disease, polycystic kidney disease, renal artery stenosis (renovascular hypertension), hyperaldosteronism, obstructive uropathy, renal vasculitis, reninomas |
| Neurological | Acute stress (surgery), psychogenic, high intracranial pressure, sleep apnoea |
| Physiologic | Increase in growth hormone, hypothyroidism (retained fluids, myxoedema), hyperthyroidism, pregnancy |
- Pathophysiological changes associated with hypertension
- Hyaline arteriolosclerosis: Seen in benign essential hypertension, old age, and diabetes. Collagen is laid down in the tunic media, narrowing the lumen and decreasing compliance. Narrowing is worse at branch points.
- Hyperplastic arteriosclerosis: seen in malignant hypertension, concentric laminated thickening of the arteriole walls, onion skin appearance, and luminal narrowing
- Necrotizing arteritis: characterized by focal fibrinoid necrosis in hypertrophic vessels
- Investigations
- Urinalysis to screen for albuminuria and glucosuria (for hypertensive nephropathy)
- U/E/C to Check K+, BUN, and Creatinine (for hypertensive nephropathy)
- Random Blood Sugar to check for hyperglycemia
- Electrocardiography or Echocardiography: to check for structural abnormalities seen in hypertensive heart disease
- Left Ventricular Hypertrophy
- Lipid Profile to check LDL (Hyperlipidemia + Hypertension multiplies risk for complications)
- Investigations to exclude secondary causes
- U/E/C for hypokalemia in Conn’s
- Serum calcium for hypercalcemia in hyperparathyroidism
- Renal ultrasound for renal artery stenosis
- 24 urine meta-adrenaline for phaechromocytoma
- Urinary free cortisol for Cushing’s syndrome
- Renin: aldosterone ratio for hyperaldosteronism
- Magnetic Resonance Aorta for coarctation of the aorta
- Complications of Hypertension
- Hypertensive Heart Disease
- Atrial fibrillation
- Coronary artery disease
- Stroke
- Vascular dementia
- Chronic kidney disease
- Metabolic syndrome
- Hypertensive nephropathy
- Hypertensive retinopathy
- Placental changes
- Eclampsia
- Intrauterine Fetal Death
- Intrauterine Fetal Growth Restriction