Hypertension

Hypertension Overview

Normal Blood Pressure Levels

  • Defined as systolic/diastolic pressure levels that are healthy.

Definition and Prevalence of Hypertension (HTN)

  • Hypertension (HTN) occurs when Mean Arterial Pressure (MAP) is maintained at or above 140/90 mmHg.

  • Approximately 1/3 of adults in England are affected by HTN.

  • Chronic elevation in blood pressure leads baroreceptors to "reset," continuing regulation at a higher pressure level.

  • HTN is often referred to as the ‘silent killer’ due to the absence of symptoms.

Complications of Hypertension

  • Stress on Heart & Blood Vessels: Increased effort required to pump blood.

  • Congestive Heart Failure: Heart's inability to pump effectively.

  • Stroke: Disruption of blood flow to the brain.

  • Myocardial Infarction: Heart attack resulting from blocked blood supply.

  • Renal Failure: Damage to kidneys due to high blood pressure.

Treatment for Hypertension

  • Medications: Diuretics and antihypertensive drugs.

  • Lifestyle Changes: Regular exercise, weight control, and dietary modifications.

Types of Hypertension

Primary Hypertension (Essential/Idiopathic)

  • Causes: Genetic predisposition; influenced by lifestyle options such as stress, obesity, smoking, and diet.

  • Current Research Insights:

    • Salt management issues, both dietary and renal.

    • Diets lacking fruits, vegetables, and dairy (deficiencies in potassium and calcium).

    • Abnormalities in plasma membranes, including defective sodium-potassium pumps.

    • Excessive vasopressin production.

    • Gene abnormalities affecting vasoactive chemical levels.

Secondary Hypertension

  • Occurs in 5-10% of HTN cases and is a response to a primary medical issue.

  • Typically has a clear, identifiable cause, such as reduced blood flow through the kidneys that stimulates hormone release to increase MAP.

Hypotension and Orthostatic Hypotension

Orthostatic Hypotension

  • Relates to changes from a horizontal position to vertical.

  • Insufficient compensatory responses to gravitational blood shifts can lead to:

    • Blood pooling in leg veins.

    • Decreased venous return (VR), end-diastolic volume (EDV), stroke volume (SV), cardiac output (CO), and mean arterial pressure (MAP).

  • Normally, baroreceptor reflexes correct MAP, but in cases of disuse, this reflex can be lost.

  • Symptoms: Dizziness and fainting from diminished blood flow to the brain.

General Hypotension

  • Defined as having MAP lower than 90/60 mmHg.

  • Results in inadequate blood flow to tissues.

  • Causes:

    • Imbalance between vascular capacity and blood volume.

    • Weak heart unable to generate necessary pressure for effective blood distribution.