Understanding Hypertension

Study Notes

Overview of Hypertension

Hypertension is characterized by consistently elevated systolic blood pressure (over 140 mm Hg) and diastolic blood pressure (over 90 mm Hg).
Approximately 30% of adults in the U.S. suffer from hypertension, increasing risks for heart disease, stroke, chronic kidney disease, and heart failure.
Early detection and treatment are essential to mitigate serious health complications.

Etiology of Hypertension

Essential hypertension accounts for over 90% of cases, lacking a definitive cause, while secondary hypertension arises from other medical conditions.
Risk factors include family history, age, race (higher in Non-Hispanic Blacks), diabetes, obesity, stress, high sodium intake, and smoking.

Mechanisms for Controlling Blood Pressure

Blood pressure is maintained by the relationship: Blood Pressure = Cardiac Output x Peripheral Resistance.
Baroreceptors detect blood pressure changes, activating the sympathetic nervous system to induce vasoconstriction and increase cardiac output during hypotension.

Diuretics

Diuretics lower blood pressure by reducing blood volume and should include routine electrolyte monitoring.
Thiazide diuretics (e.g., Hydrochlorothiazide, Chlorthalidone) enhance sodium and water excretion but have limitations when renal function is impaired.
Loop diuretics (e.g., Furosemide, Bumetanide) are effective in patients with low kidney function, enhancing renal blood flow.
Potassium-sparing diuretics (e.g., Spironolactone) prevent potassium loss and help in heart failure management.

β-Adrenoceptor-Blocking Agents (β-Blockers)

β-blockers primarily lower blood pressure by reducing cardiac output and inhibiting renin release.
Non-selective β-blockers (e.g., Propranolol) block both β1 and β2 receptors and are contraindicated in asthma patients.
Selective β1-blockers (e.g., Metoprolol, Atenolol) are safer for asthma and provide therapeutic benefits for heart disease and chronic heart failure.
Common adverse effects include bradycardia, hypotension, and fatigue, with risks of rebound hypertension upon abrupt discontinuation.

ACE Inhibitors

ACE inhibitors (e.g., Enalapril, Lisinopril) decrease blood pressure by hindering the conversion of angiotensin I to angiotensin II and enhancing vasodilation.
Useful in managing conditions like coronary disease, diabetes, and heart failure; most are prodrugs activated in the body.
Side effects may include cough and angioedema.

Calcium Channel Blockers

Calcium channel blockers facilitate smooth muscle relaxation in blood vessels, lowering blood pressure without affecting venous dilation.
Effective for hypertension, angina, and specific arrhythmias; they feature varying pharmacokinetic properties.
Side effects can include dizziness, headache, and peripheral edema.

α-Adrenoceptor-Blocking Agents

Agents like Prazosin and Doxazosin block α1 receptors, reducing peripheral vascular resistance and blood pressure.
Not recommended as first-line treatment due to side effects but may be beneficial for refractory hypertension and BPH.

α-/β-Adrenoceptor-Blocking Agents

Agents such as Labetalol and Carvedilol block α and β receptors, used in hypertensive emergencies and managing heart failure.
Labetalol is effective in acute situations, while Carvedilol targets heart failure management.

Centrally Acting Adrenergic Drugs

Clonidine and Methyldopa lower blood pressure via central mechanisms, decreasing sympathetic outflow.
Clonidine is particularly effective in resistant hypertension, while Methyldopa is safe during pregnancy.

Vasodilators

Hydralazine and Minoxidil directly relax smooth muscle, reducing blood pressure.
Often combined with β-blockers and diuretics for effective hypertension management; side effects may include reflex tachycardia and fluid retention.

Hypertensive Emergency

Defined as severe hypertension (>180/120 mm Hg) with potential target organ damage.
Treatment options include calcium channel blockers, nitric oxide vasodilators, adrenergic receptor antagonists, and Dopamine agonists.
The goal is to quickly reduce blood pressure to prevent further organ damage, tailored to specific clinical scenarios.

Description

This quiz provides an overview of hypertension, including its definition and the criteria for diagnosing high blood pressure. Explore the effects and risks associated with hypertension and understand its impact on blood vessel resistance. Test your knowledge and awareness of this common health condition.