patho exam 3 (copy)

Cardiovascular System

Function of the Cardiac System, Cardiac Output, Terminology, Calculations, Starling’s Law

  • Function of the Cardiac System:

    • Pumps blood to supply oxygen and nutrients to tissues.

    • Regulates blood pressure and perfusion through cardiac output (CO) and vascular resistance.

  • Cardiac Output (CO):

    • CO = Stroke Volume (SV) × Heart Rate (HR)

    • SV: Volume of blood ejected per beat (average ~70 mL), which can vary notably with factors such as heart condition, physical fitness, and body position.

    • HR: Beats per minute (normal ~60-100 bpm); affected by factors such as age, fitness level, hormonal influences, and autonomic nervous system tone.

    • Normal CO: ~4-8 L/min; can increase significantly during exercise to meet greater tissue oxygen demands.

  • Terminology:

    • Preload: The volume of blood returning to the heart; determines stretch on the ventricular walls before contraction. Greater preload increases the force of contraction due to stretch of heart muscle fibers.

    • Afterload: The resistance the heart must pump against to eject blood (e.g., hypertension increases afterload). High afterload can lead to decreased stroke volume and increased myocardial oxygen demand.

    • Contractility: The heart’s ability to contract forcefully, influenced by factors such as heart muscle health and sympathetic stimulation.

  • Starling’s Law:

    • The more the heart is stretched (↑ preload), the stronger it contracts (up to a point). This relationship is crucial for balancing heart output with venous return. However, excessive stretch can lead to heart failure as the heart muscle may become overstretched, compromising its ability to pump effectively.

Atherosclerosis: Complications

  • Atherosclerosis: Hardening of arteries due to plaque buildup (lipids, cholesterol, calcium), which narrows the arterial lumen and impairs blood flow.

  • Complications:

    • Coronary artery disease (CAD): Leads to angina (chest pain) and myocardial infarction (MI) due to reduced blood flow to the heart muscle.

    • Stroke (CVA, TIA): Ischemic strokes arise from blood clots interrupting blood flow to the brain; potentially reversible symptoms occur with transient ischemic attacks (TIA).

    • Peripheral artery disease (PAD): Results in symptoms like claudication (leg pain with exertion), risk of ulcers, and gangrene due to lack of blood supply especially in lower extremities.

    • Aneurysms: Weakening and dilation of an artery wall can lead to rupture, causing life-threatening internal bleeding.

    • Hypertension: Increases cardiac workload, promoting heart failure and further vascular risks.

Pericarditis: Clinical Manifestations, Complications

  • Pericarditis: Inflammation of the pericardium (the outer layer surrounding the heart) due to infection, myocardial infarction, or autoimmune disease.

  • Clinical Manifestations:

    • Sharp Chest Pain: Worsens when lying down and improves with sitting up, often described as pleuritic.

    • Pericardial Friction Rub: Characteristic scratching sound heard on auscultation indicating inflammation.

    • Fever & ↑ WBCs: Indicate infection or inflammatory process.

  • Complications:

    • Cardiac Tamponade: A serious condition where fluid accumulation compresses the heart, hindering its ability to pump effectively; requires urgent intervention.

    • Pericardial Effusion: Excess fluid in the pericardial sac that may cause similar symptoms to cardiac tamponade if large enough.

Myocardial Infarction (MI): Clinical Manifestations

  • Myocardial Infarction (MI): Occurs when blood flow to a part of the heart is blocked, resulting in ischemia and tissue necrosis.

  • Classic Symptoms (Men):

    • Severe chest pain: Often described as crushing pain that may radiate to the jaw or left arm.

    • Associated Symptoms: Diaphoresis (sweating), nausea, shortness of breath (SOB).

  • Atypical Symptoms (Women, Elderly, Diabetics):

    • Fatigue, nausea, jaw pain, dyspnea, back pain. These patients may not experience classic chest pain and often present differently.

  • Complications:

    • Arrhythmias: Irregular heartbeats that can lead to further complications.

    • Cardiogenic shock: Heart's inability to pump sufficient blood to meet the body's needs.

    • Heart failure: Resulting from damage to the heart muscle post-infarction.

    • Death: Significant risk if not treated promptly.

Ischemic Cardiomyopathy: Pathophysiology

  • Ischemic Cardiomyopathy: Results from chronic ischemia due to CAD, leading to a weakened heart muscle, ultimately resulting in heart failure.

  • Pathophysiology:

    • Repeated low oxygen supply leads to myocardial scarring and reduced contractility over time, exacerbating heart failure.

    • Structural changes include a dilated left ventricle and reduced ejection fraction, along with signs of chronic heart failure.

Peripheral Artery Disease (PAD): Clinical Manifestations

  • PAD: Atherosclerosis affects peripheral arteries, particularly in the legs.

  • Symptoms:

    • Intermittent claudication: Characterized by leg pain during activity, which is relieved by rest.

    • Other Signs: Coldness, paleness, weak pulses in the legs; advanced stages can lead to non-healing ulcers and gangrene.

Hyperlipidemia: Clinical Manifestations

  • Hyperlipidemia: Elevated levels of LDL (“bad cholesterol”) contribute to atherosclerosis.

  • Signs:

    • Xanthomas: Fatty deposits that can appear on the skin, particularly around the eyes.

    • Arcus Senilis: A gray or white arc visible around the cornea of the eye, indicating cholesterol deposits.

Endocarditis: Clinical Manifestations

  • Endocarditis: Bacterial infection affecting heart valves, usually resulting from bacteremia.

  • Signs:

    • Systemic Symptoms: Fever, night sweats, and associated chilliness.

    • Cardiac Symptoms: A heart murmur, which can be detected on auscultation.

    • Skin Manifestations: Janeway lesions (non-painful red spots on palms/soles) and Osler’s nodes (painful lesions on fingers/toes).

Heart Failure (HF): Pathophysiology, Clinical Manifestations

  • Heart Failure (HF): The heart's inability to pump effectively leads to fluid overload and hypoxia in body organs.

  • Left-Sided HF (Lung Symptoms):

    • Symptoms include pulmonary edema (crackles, dyspnea, pink frothy sputum), orthopnea (difficulty breathing while lying down), and paroxysmal nocturnal dyspnea (waking up gasping for air).

  • Right-Sided HF (Body Symptoms):

    • Signs include peripheral edema (swelling of extremities), ascites (fluid in the abdominal cavity), jugular venous distention (JVD), and hepatomegaly (enlargement of the liver).

Systems to Regulate & Compensate for Blood Pressure Abnormalities

  • Baroreceptors: Mechanoreceptors that sense blood pressure changes; coordinate the autonomic nervous system response to adjust heart rate and vessel constriction.

  • RAAS System: Activated during low BP; promotes vasoconstriction, increases blood volume, and raises blood pressure by retaining sodium and water via the kidneys.

  • ADH (Vasopressin): Hormone released by the pituitary gland that retains water in the body, thereby increasing blood volume and blood pressure.

Mitral Stenosis: Clinical Manifestations, Complications

  • Mitral Stenosis: Narrowing of the mitral valve leads to increased left atrial pressure and pulmonary congestion.

  • Symptoms:

    • Dyspnea, fatigue, palpitations, and a characteristic diastolic rumble on auscultation.

  • Complications:

    • Risk of atrial fibrillation, which can lead to thromboembolic events, pulmonary hypertension, and eventual heart failure.

Virchow’s Triad (Risk Factors for Clots)

  • Components of Virchow’s Triad:

    • Endothelial Injury: Causes include trauma, surgery, and factors like smoking that can damage blood vessels.

    • Venous Stasis: Conditions like immobility, prolonged pregnancy, or long-distance travel can slow venous blood flow.

    • Hypercoagulability: States that increase clotting potential, including certain cancers, use of hormonal birth control, or genetic disorders.

Deep Vein Thrombosis (DVT): Risk Factors, Complications, PE

  • DVT: Formation of a blood clot in a deep vein, typically in the legs.

  • Risk Factors: Align with Virchow’s Triad.

  • Complications:

    • Pulmonary Embolism (PE): Occurs when a thrombus breaks free and travels to the pulmonary artery, resulting in impaired oxygenation and can lead to sudden death if severe.

Hematologic & Endocrine Disorders (Module 9)

  • DIC & ITP: Clinical Manifestations

    • DIC (Disseminated Intravascular Coagulation): Characterized by both excess clotting and bleeding, resulting in signs like petechiae, bruising, bleeding from multiple sites, and organ failure.

    • ITP (Immune Thrombocytopenic Purpura): An autoimmune disorder leading to the destruction of platelets, resulting in purpura, frequent nosebleeds, and heavy menstrual periods.

  • Endocrine Disorders

    • Graves’ Disease: A common cause of hyperthyroidism, presenting with symptoms like heat intolerance, weight loss, and exophthalmos (protruding eyes).

    • Parathyroid Disorders: Calcium imbalances are significant in both hyper and hypoparathyroidism, affecting bone density and neuromuscular function.

    • Adrenal Disorders:

      • Addison’s Disease: Characterized by deficient cortisol production leading to symptoms such as fatigue and weight loss.

      • Cushing’s Syndrome: Resulting from excess cortisol, presenting with characteristic features like moon face and buffalo hump.

    • Diabetes:

      • Type 1: Autoimmune destruction of insulin-producing beta cells leads to absolute insulin deficiency.

      • Type 2: Generally characterized by insulin resistance and relative insulin deficiency.

      • Complications: Diabetic Ketoacidosis (DKA) in Type 1 and Hyperglycemic Hyperosmolar State (HHS) in Type 2 are severe conditions requiring urgent medical attention.