Cardiovascular Disorders Part 1

Cardiovascular Disorders Part 1

• Specific Diseases: Diseases of arteries and veins include varicose veins, chronic venous insufficiency, thrombus formation in veins, superior vena cava syndrome, hypertension, hypotension, aneurysm, thrombus formation, embolism, thromboangiitis obliterans, Raynaud's phenomenon, arteriosclerosis, peripheral arterial disease, and shock.

Review of Cardiovascular System

Heart Structure

• Right Heart: Pumps blood through the lungs.
• Pulmonary Circulation: Blood flow through the lungs.
• Left Heart: Pumps blood through the body.
• Systemic Circulation: Blood flow through the body.

The Heart

• Heart Wall: Has three layers enclosed in the pericardium: epicardium (outer layer), myocardium (cardiac muscle), and endocardium (inner lining).
• Pericardium: The pericardial sac encloses the heart. A thin pericardial cavity contains fluid.

Structure of the Heart

• Atria: Right atrium and left atrium.
• Ventricles: Right ventricle and left ventricle.
• Valves: Atrioventricular valves (tricuspid and mitral) and semilunar valves (pulmonic and aortic).

Valves of the Heart

• Atrioventricular (AV) Valves: Tricuspid and mitral.
• Semilunar Valves: Pulmonic and aortic.

Great Vessels

• Venae Cavae: Superior and inferior.
• Pulmonary Artery: Carries blood from the heart to the lungs.
• Pulmonary Arteries: Right and left.
• Pulmonary Veins: Carry oxygenated blood from the lungs to the heart.
• Aorta: Carries oxygenated blood from the heart to the body.

Blood Flow and Cardiac Cycle

Coronary Vessels

• Coronary Arteries: Supply blood to the heart muscle. Includes right coronary artery, right marginal branch, posterior descending branch, and left coronary artery, left anterior descending artery, circumflex artery, collateral arteries, and coronary capillaries.

Structures That Control Heart Action

• Cardiac Action Potentials: Electrical signals that trigger heart muscle contraction.
• Conduction System: Sinoatrial node (SA node), atrioventricular node (AV node), Bundle of His, right and left bundle branches, and Purkinje fibers.

Structures That Control Heart Action (Cont.)

• Propagation: How the action potential spreads through the heart.
• Resting Membrane Potential: The electrical charge difference across the cell membrane when the cell is at rest.
• Depolarization/Repolarizations: Changes in electrical charge across the membrane.
• Hyperpolarization: Electrical charge becomes more negative than the resting potential.
• Refractory Period: Time period where the cell cannot be stimulated for a new contraction.
• Electrocardiogram (ECG or EKG): Electrical activity of the heart.
• Automaticity/Rhythmicity: Heart's ability to contract rhythmically without external stimulation.

Myocardial Cells and Contraction

• Myocardial Contraction and Relaxation: Involves the cross-bridge theory, excitation-contraction coupling, calcium channels (L-type, T-type), etc.

Cardiac Performance

• Cardiac Output: The volume of blood pumped by the heart per minute.
• Preload: Pressure in the ventricle at the end of diastole (relaxation phase); volume of blood in the ventricle at the end of diastole.
• Afterload: Resistance to blood leaving the ventricle.
• Cardiac Output (Cont.): Stroke volume and preload (volume and how contractile the muscle is), inotropic agents (drugs that alter contractility), and oxygen/carbon dioxide levels play a role in determining cardiac output. Also volume of blood through systemic or pulmonary circuit per minute.

Cardiac Performance (Cont.)

• Myocardial Contractility: The ability of the heart muscle to contract forcefully.
• Stroke Volume: The volume of blood pumped by a ventricle per beat.
• Ejection Fraction: Percentage of blood ejected from the ventricle per beat.

Systemic Circulation

• Arteries: Carry blood away from the heart.
• Arterioles: Small branches of arteries.
• Capillaries: Tiny vessels where gas exchange occurs.
• Venules: Small veins.
• Veins: Carry blood back to the heart.

Structure of Blood Vessels

• Lumen: The central opening of a blood vessel.
• Tunica Intima: Inner layer of a blood vessel.
• Tunica Media: Middle layer, mostly composed of smooth muscle.
• Tunica Externa: Outer layer.

Factors Affecting Blood Flow

• Pressure: Force exerted on a liquid per unit area.
• Resistance: Opposition to force (related to vessel diameter, length).

Baroreceptor and Chemoreceptors

• Baroreceptors: Measure blood pressure.
• Chemoreceptors: Monitor blood levels of chemicals such as oxygen and carbon dioxide.

Regulation of Blood Pressure

• Arterial Pressure: Blood pressure in the arteries.
• Mean Arterial Pressure (MAP): Average arterial pressure during one cardiac cycle.
• Effects of Cardiac Output: Volume of blood pumped per minute.
• Effects of Total Peripheral Resistance: Resistance to flow of blood from the heart.
• Effects of Hormones/Other Mediators: Include hormones (epinephrine, norepinephrine, ADH, renin-angiotensin-aldosterone system, atrial natriuretic peptides), and nitric oxide, adrenomedullin etc.

Cardiovascular Disease

Cardiac Diseases

• Diseases of arteries and veins: Varicose veins, chronic venous insufficiency, thrombus formation, superior vena cava syndrome, hypertension, hypotension, aneurysm, thrombus formation, embolism, etc.

Varicose Veins

• Pathophysiology: Polling of blood due to trauma or venous distension (especially saphenous vein).
• Clinical Manifestations: Distended, tortuous, palpable veins.

Chronic Venous Insufficiency

• Pathophysiology: Inadequate venous return over a long period. Caused by varicose veins or valvular incompetence, causing venous hypertension, circulatory stasis, and tissue hypoxia.
• Clinical Manifestations: Edema, hyperpigmentation, ulcers.

Venous Thrombus Formation

• Pathophysiology: Obstruction of venous flow, increased venous pressure. Accumulation of clotting factors and platelets.
• Etiology: (Factors that promote): Venous stasis, endothelial damage (trauma, medications), hypercoagulable states (inherited factors, malignancy, pregnancy, etc.).

Superior Vena Cava Syndrome

• Causes: Progressive occlusion of the superior vena cava due primarily to cancer (75% bronchogenic), lymphoma or other causes.
• Pathophysiology: Swollen, distended upper extremities and face, visual disturbances, headaches, impaired consciousness, and respiratory distress.
• Diagnostics: Chest x-ray, CT, and MRI.

Hypertension

• A consistent elevation of systemic arterial blood pressure. This is indicated by a systolic blood pressure of 140mmHg or greater, and a diastolic pressure of 90 mmHg or greater (nonautomated office BP measurement).
• Risk factors: Age, diabetes mellitus (DM), chronic kidney disease (CKD), diet, sedentary lifestyle, ancestry, etc.
• Pathophysiology: Sustained increase in peripheral resistance (arteriolar vasoconstriction), increased blood volume, inflammation, endothelial dysfunction, hormones, etc.
• Secondary hypertension: caused by an underlying disorder.

Orthostatic (Postural) Hypotension

• Pathophysiology: Decrease in blood pressure on standing. Usually within 3 minutes. Caused by lack of normal blood pressure compensation in response to gravitational changes, certain medications, prolonged immobility, dehydration/starvation, etc.

Aneurysm

• Pathophysiology: Local dilation or outpouching of a vessel wall. Weakening/Dilation in artery.
• Types:
  • Fusiform (circumferential).
  • Saccular.
  • False.
• Causes:
• Genetic predisposition, smoking, atherosclerosis, and other diseases.

Arterial Thrombi

• Pathophysiology: A blood clot formed in an artery that remains attached to the vessel wall.
• Causes:
• Injury to the artery wall, blood pooling, inflammation.
• Clinical Manifestations: Vary depending on the location and size of the thrombus.

Embolism

• Types: Dislodged thrombus, air bubble, amniotic fluid, fat, bacteria, cancer cells, or foreign material.
• Pathophysiology: Travels until it gets lodged in a vessel.

Thromboangiitis obliterans (Buerger's disease)

• Pathophysiology: Inflammation of the small and medium sized arteries.
• Cause: strongly associated with smoking.
• Clinical Manifestations: Pain, rubor, and cyanosis in affected areas, thickening of the skin and nails.

Raynaud's phenomenon

• Pathophysiology: Episodic vasospasms (narrowing) in the arteries and arterioles of the fingers or less commonly, the toes. Often in response to cold or stress/emotional response.
• Primary: No known cause.
• Secondary: secondary to other systemic diseases/conditions.

Arteriosclerosis

• Abnormal thickening and hardening of the arterial vessel walls. Includes atherosclerosis (primarily lipid build-up)

Atherosclerosis

• Pathophysiology: Injury to arterial endothelial cells leads to fatty streaks in the wall.
• Causes and Risk Factors: Smoking, diabetes, high LDL/low HDL, high blood pressure, etc.
• Formation of plaques: Macrophage accumulation, cellular proliferation; oxidation and inflammation of LDL, macrophages; fibrous plaque and the complicated lesion.

Peripheral Arterial Disease (PAD)

• Pathophysiology: Atherosclerotic disease of arteries supplying the limbs.
• Causes: Intermittent claudication (pain with movement), complete obstruction or thrombosis, etc.
• Symptoms: Pain, tenderness, loss of pulses, skin colour changes.

Shock (General)

• Definition/Patho: Cardiovascular system fails to adequately perfuse tissues.
• Causes and mechanisms: impaired oxygen use, impaired glucose use. (e.g., cellular damage, volume depletion, etc.).

Types of Shock (Specific):

• Cardiogenic shock: Failure of the heart to pump adequate blood volume.
• Hypovolemic: Loss of blood volume, fluid loss.
• Neurogenic: Dysfunction of the autonomic nervous system (may include injury to the spinal cord).
• Anaphylactic: Allergic reaction. This can lead to widespread vasodilation.
• Septic: Infection in the blood that causes widespread inflammation.

Diagnostic tests

• Cardiac tests, blood tests, stress tests, echocardiograms, angiographies, etc.

Explore the complexities of cardiovascular disorders with this informative quiz. Covering diseases of arteries and veins, along with a review of heart structure and function, this quiz is perfect for students studying cardiology or related fields. Test your knowledge on conditions like hypertension, aneurysms, and the mechanisms of blood circulation.