Blood Pressure, Cardiac Output and Diuretics

• The circulatory system's blood distribution is 9% in pulmonary circulation, 7% in the heart, and 84% in systemic circulation.
• Blood flow occurs when the force that drives the flow is greater than the resistance.

Cardiac Output

• Cardiac output is determined by heart rate multiplied by stroke volume.
• Determinants of cardiac output include heart rate, stroke volume, preload, and afterload.
• Starling's law of the heart is a key factor in cardiac function.

Regulatory Systems

• The baroreceptor reflex, RAAS (Renin-Angiotensin-Aldosterone System), and natriuretic peptides regulate blood pressure.

Hypotension

• Hypotension is low blood pressure.

Diuretics: Mechanism and Action

• Diuretics work by blocking sodium and chloride reabsorption in the kidneys.
• The proximal tubule produces the greatest diuresis.
• Diuretics can cause adverse effects such as hypovolemia and acid-base and electrolyte imbalances.

Diuretics: Classes

• Four major classes of diuretics include loop diuretics, thiazide diuretics, osmotic diuretics, and potassium-sparing diuretics.
• Loop diuretics include furosemide.
• Thiazide diuretics include hydrochlorothiazide.
• Osmotic diuretics include mannitol.
• Potassium-sparing diuretics have two subcategories: aldosterone antagonists (like spironolactone) and nonaldosterone antagonists (like triamterene).
• A fifth group is carbonic anhydrase inhibitors.

Specific Diuretics

• Loop diuretics: furosemide, ethacrynic, bumetadine, and torsemide.
• Thiazides: hydrochlorothiazide.
• Potassium-sparing diuretics: spironolactone and amiloride.

Renin-Angiotensin-Aldosterone System (RAAS)

• Types of angiotensin include angiotensin I, angiotensin II, and angiotensin III.
• Angiotensin II formation occurs via renin and angiotensin-converting enzyme (ACE).
• The renin-angiotensin-aldosterone system regulates blood pressure.
• Angiotensin II is also produced in tissues locally.

ACE Inhibitors

• ACE inhibitors include benazepril, captopril, and enalapril.
• Some ACE inhibitors are combined with HCTZ (hydrochlorothiazide).

ACE Inhibitors: Interactions

• Drug interactions with ACE inhibitors include diuretics, antihypertensive agents, drugs that raise potassium levels, lithium, and nonsteroidal anti-inflammatory drugs.

Calcium Channel Blockers

• Calcium channel blockers prevent calcium ions from entering cells, impacting the heart and blood vessels.
• These drugs treat hypertension, angina pectoris, and cardiac dysrhythmias.
• Calcium channel blockers are also known as calcium antagonists and slow channel blockers.
• Verapamil and diltiazem affect vascular smooth muscle and the heart.
• Dihydropyridines mainly affect vascular smooth muscle.

Vasodilation

• Vasodilation can be achieved with various drugs acting on veins, arterioles, or both.
• Drugs that dilate resistance vessels (arterioles) decrease cardiac "afterload".
• Drugs that dilate capacitance vessels (veins) reduce preload.

Hypertension Types

• Primary (essential) hypertension has no identifiable cause.
  • It is chronic, progressive, and more common in older adults, African Americans, and postmenopausal women.
  • It can be treated but not cured.
• Secondary hypertension has an identifiable primary cause that can potentially be treated directly.

Heart Failure Forms

• Systolic heart failure involves left ventricular dysfunction.
• Diastolic heart failure, also known as heart failure with preserved LV ejection fraction.

Heart Failure Characteristics

• Heart failure is a progressive and often fatal disorder characterized by left ventricular dysfunction, reduced cardiac output, insufficient tissue perfusion, and fluid retention.

Heart Faliure Drugs

• Drugs for heart failure include diuretics and RAAS inhibitors.
• RAAS inhibitors include angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, aldosterone antagonists, and direct renin inhibitors.
• Further drugs include beta blockers, digoxin, dopamine, and hydralazine

Dysrhythmia

• Dysrhythmia is an abnormality in the rhythm of the heartbeat.
• Tachydysrhythmias can be supraventricular or ventricular.
• Bradydysrhythmias are a form of dysrhythmia.
• Drugs that treat dysrhythmias can also cause dysrhythmias.

Coronary Heart Disease Prophylaxis

• High cholesterol and plasma lipoproteins contribute to Coronary Heart Disease.
• LDL cholesterol plays a role in atherosclerosis.

Angina Pectoris

• Angina pectoris is sudden pain beneath the sternum, often radiating to the left shoulder and arm.
• It results from insufficient oxygen supply to meet the heart's oxygen demand.

Angina Pectoris Treatment

• Goals include preventing myocardial infarction, death, myocardial ischemia, and anginal pain.
• Therapeutic agents include organic nitrates, beta blockers, calcium channel blockers, and ranolazine.
• Non-drug therapy involves avoiding factors that precipitate angina and decreasing risk factors.

Thromboembolic Disorders

• Anticoagulants disrupt the coagulation cascade and suppress fibrin production.

Thromboembolic Drugs

• Antiplatelets inhibit platelet aggregation.
• Thrombolytics promote fibrin lysis, dissolving thrombi.
• Available LMW heparins include enoxaparin, dalteparin, and tinzaparin.
• Other medications include warfarin, dabigatran etexilate, bivalirudin, desirudin, argatroban, and rivaroxaban.

Anemias

• Anemias are a decrease in erythrocytes (RBCs) in number, size, or hemoglobin content.
• Causes include blood loss, hemolysis, and bone marrow dysfunction.
• Anemias can result from a deficiency of substances essential for RBC formation and maturation.

Explore blood distribution, flow dynamics, and cardiac output determinants including Starling's law. Learn about regulatory systems like the baroreceptor reflex and RAAS. Understand diuretics, their mechanisms, classes, and potential adverse effects such as hypovolemia and electrolyte imbalances.