Hypertension: Understanding Blood Pressure

Definition and Measurement of Hypertension

• Hypertension is an abnormal elevation in arterial pressure that can be fatal if sustained and untreated.
• Blood pressure is the product of cardiac output and peripheral resistance, dependent on the heart, vasculature, autonomic nervous system, endocrine system, and kidneys.
• Hypertension in adults is defined as a sustained systolic blood pressure of 140 mmHg or greater and/or a sustained diastolic blood pressure of 90 mmHg or greater.

Components of Blood Pressure

• Systolic pressure is the force exerted on artery walls as the heart contracts to pump blood to peripheral organs.
• Diastolic pressure is the residual pressure exerted on arteries as the heart relaxes.
• Pulse pressure is the difference between diastolic and systolic pressures.
• Mean arterial pressure is roughly defined as the sum of diastolic pressure plus one-third the pulse pressure.

Types of Hypertension

Primary/Essential/Idiopathic Hypertension

• Accounts for about 90% of all cases of hypertension with no readily identifiable cause.
• Has a genetic link and is often associated with cardiovascular risk factors, smoking, obesity, lipid problems, and diabetes.

Secondary Hypertension

• Always due to an underlying cause such as intrinsic renal diseases, renovascular disease, pheochromocytoma, Cushing's syndrome, thyroid or parathyroid disease, heavy alcohol consumption, chronic corticosteroid therapy, chronic NSAIDs therapy, or long-term oral contraceptive use.
• Symptoms appear earlier and are more severe compared to primary/essential hypertension.
• Many patients can be cured after treatment of the underlying cause.