Week 6: Inflammatory and Structural Heart Disorders

Inflammatory & Structural Heart Disorders

Overview of Cardiac Disorders

  • Key focus on inflammation and decreased cardiac output, leading to altered tissue perfusion.

Part 1: Infective Endocarditis
Definition

  • Infective Endocarditis is an infection of the endocardium, which lines the heart and forms the heart valves.

  • Commonly caused by bacteria (e.g., staphylococci, enterococci) but can also be due to fungal infections.

Structure of the Heart

  • Pericardium (sac surrounding the heart):

    • Fibrous Pericardium (outer layer)

    • Serous Pericardium:

      • Visceral layer (epicardium)

      • Parietal layer

  • Heart Wall Components:

    • Myocardium (muscle layer; part of the muscle dies due to infarction/death due to lack of oxygen)

    • Endocardium (inner lining covering trabeculae; they form the valves)

Causes of Infective Endocarditis

  • Modes of Infection:

    • Use of shared needles

    • Direct contamination

    • Surgical or dental procedures

    • Development from a systemic infection.

Pathophysiology

  • Colonization of microbes occurs at sites of abnormalities or injuries (e.g., prolapsing valves, injured valves, or artificial valves).

  • The inflammatory response leads to endothelial damage, promoting clustering of platelets, fibrin, white blood cells (WBCs), and bacteria (a vegetation). This forms around the valves. Can be a viral or fungal infection.

  • Vegetations form on the endocardium:

    • Fragile and easily crumbled, can break off, causing emboli.

    • Can damage valve leaflets and mechanical valves, leading to abscess formation.

Risk Factors for Infective Endocarditis

  • Pre-existing heart disease.

  • Intravenous (IV) drug use.

  • Cardiac valvular diseases.

    • Rheumatic heart disease.

    • Presence of prosthetic valves.

    • Congenital and structural abnormalities (e.g., mitral valve prolapse).

      • Common valve replacements: aortic valve (blood from the left ventricles to the rest of the body) and mitral (between the left atrium and left ventricle).

        • Mechanical replacements, the client needs to be on anticoagulation therapy, and you’ll hear a click upon auscultation.

        • Biological ones, which come from animals, deteriorate more quickly.

  • Long-term intravenous catheters.

  • Recent body piercings or similar procedures.

Clinical Manifestations

  • Symptoms:

    • Rapid onset with fever and chills.

    • Subacute presentations with gradual onset, low-grade fever, and constitutional symptoms.

    • Notable signs include heart murmurs, worsening with vegetation damage.

    • General symptoms may include myalgias and joint pain. Fever is not mandatory.

  • Specific Signs:

    • Splinter Hemorrhages and Petechiae (occurring in ~40% of cases due to hemorrhage from distal capillaries).

      • Petechiae: common in those with low platelets/thrombocytopenia.

    • Osler Nodes: Painful, red nodules in fingers/toes due to microemboli.

    • Janeway Lesions: Painless red or purple macules on palms or soles.

Embolization Risks

  • Left-sided heart embolizations can impact major organs (e.g., brain, kidneys, liver, spleen).

  • Right-sided heart embolizations primarily affect the lungs.

Management

  • Antibiotics for treating infections.

    • Obtain a blood culture to diagnose and determine how to treat the infection.

  • Monitoring for local valve damage and potential complications: sepsis, heart failure, and heart block.

Part 2: Acute Pericarditis
Definition

  • Inflammation of the pericardium, the protective sac around the heart.

    • Holds the heart in place.

    • Baroreceptors control heart rate and BP.

Structure of the Pericardium

  • Composed of:

    • Fibrous Pericardium (outer layer)

    • Serous Pericardium:

      • Parietal layer (outer)

      • Visceral layer (inner; epicardium)

  • Contains 15-50 ml of pericardial fluid to reduce friction.

Causes of Acute Pericarditis

  • Can be caused by infections (bacterial, viral, fungal) or secondary to inflammation from:

    • Myocardial infarction (MI)

    • Cardiac surgery

    • Malignancy

    • Lupus

  • 80% of cases are idiopathic, often thought to be viral.

  • Risk of pericardial effusion leading to cardiac tamponade (pressure on the heart). Constrictive pericarditis can occur, restricting heart movement and filling, leading to decreased cardiac output.

    • It smoothers the heart with too much fluid.

    • Tamponade: a medical emergency characterized by the accumulation of fluid in the pericardial space, which can significantly impair the heart's ability to pump effectively and requires immediate intervention.

Clinical Manifestations

  • Symptoms range from mild to severe.

  • Common symptom: Chest pain (similar to MI) characterized as:

    • Sharp

    • Aggravated by deep breaths, coughing, and lying down (indicative sign!).

    • Persistent nature, with relief upon sitting or leaning forward.

    • Retrosternal pain that can radiate.

  • Signs include:

    • Friction Rub: A distinctive heart sound arising from the rubbing of inflamed pericardial layers.

    • Commonly heard at the left lower sternal border (4th intercostal space) using the diaphragm of the stethoscope, loudest when the patient sits forward.

  • Other symptoms:

    • Fever

    • Increased white blood cell (WBC) count

    • Elevated sedimentation rate/C-reactive protein

    • Exertion-independent dyspnea

    • Widespread ST-segment elevation on 12-lead EKG

    • Possible pericardial effusion on echocardiogram.

Nursing Care for Acute Pericarditis

  • Aim to relieve pain and manage symptoms.

  • Assess for cardiac tamponade signs.

  • First-line treatments include NSAIDs (e.g., Ibuprofen, ASA, Indomethacin).

    • Given anti-inflammatories.

  • Corticosteroids are used for patients intolerant to NSAIDs, and colchicine for recurrent cases.

  • Positioning is key for comfort, providing reassurance that the symptoms are not indicative of a heart attack.

    • Relieved with sitting and leaning forward to reduce pressure from the parietal pericardium.

Part 3: Valve Disorders and Cardiomyopathy
Overview of Valvular Diseases

  • It occurs when heart valves do not function properly, affecting blood flow.

    • Stenosis: Narrowing of valve openings, reducing blood flow through the valve.

      • It doesn’t fully open or close all the way.

    • Regurgitation: Incomplete closure of valves, allowing backward blood flow.

Visual Representation of Blood Flow Through the Heart

  • Aorta: Origin point of blood after leaving the left ventricle.

  • Valves involved:

    • Mitral valve (left atrioventricular; has 2 leaflets)

    • Tricuspid valve (right atrioventricular; has 3 leaflets)

    • Pulmonary valve (out to lungs)

    • Aortic valve (out to body).

Specific Valve Disorders

  • Mitral Valve Stenosis: Constriction of the mitral valve.

  • Mitral Valve Regurgitation: Backflow of blood into the left atrium due to improper valve closure.

  • Mitral Valve Prolapse: The mitral leaflets bulge backward into the left atrium, causing regurgitation.

    • Limited to the mitral valve.

    • Common in women.

    • The mitral valve can be replaced if this issue cannot be fixed.

    • The leaflet folds downward/dips (hooding) into the left atrium during systole, which can lead to mitral regurgitation if the valve does not close properly.

  • Aortic Stenosis and Regurgitation: Aortic stenosis involves narrowed openings; regurgitation features leakage back into the left ventricle when the valve fails to close completely.

    • Regurgitation usually follows stenosis or prolapse, as it is present in relation to issues of the valve.

Diagnostic Studies for Valvular Heart Disease

  • Includes:

    • Electrocardiogram (EKG)

    • Chest X-ray

    • Echocardiogram (including Transesophageal Echocardiogram/TEE)

      • 3D Doppler echocardiography

    • Cardiac catheterization

    • Exercise stress test.

Management of Valvular Heart Disease

  • Conservative Treatments:

    • Medications and rest.

    • Percutaneous trans-luminal balloon valvuloplasty (replacement/repair of the valve): a minimally invasive procedure (percutaneously or surgically) used to open narrowed heart valves by inserting a balloon through a catheter and inflating it to widen the valve opening.

      • Annuloplasty: repair of the outer ring around the valve.

  • Surgical Treatments:

    • Valve repair and replacement.

    • Cardiac transplant in severe cases.

  • Prosthetic Valve Types:

    • Mechanical (e.g., bi-leaflet, caged-ball)

    • Tissue valves (e.g., homograft, pericardial, xenograft).

Postoperative Care for Valve Repair/Replacement

  • Monitoring for signs/symptoms of emboli and heart failure.

  • Care aligns with postoperative protocols for patients recovering from coronary artery bypass surgery.

  • High risk of post-op complications (thromboembolism, infection, arrhythmias, hemolysis).

Part 4: Cardiomyopathy
Definition

  • A group of disorders involving the myocardium, leading to mechanical and/or electrical dysfunction.

  • Results in impaired cardiac output.

Types of Cardiomyopathy

  • Dilated Cardiomyopathy (DCM): Weakened and enlarged left ventricle.

  • Hypertrophic Cardiomyopathy (HCM): A genetic condition resulting in a thickened left ventricular wall.

    • Can be seen in children.

  • Restrictive Cardiomyopathy (RCM): Rigid heart muscle restricting filling.

  • Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): Replacement of heart muscle cells with fat and scar tissue.

    • Temporary, broken heart as the muscles are weakened for a while.

  • Stress-Induced Cardiomyopathy: Typically resolves in weeks.

Dilated Cardiomyopathy Etiology

  • Results in thinning of the left ventricular wall and increased chamber size and volume.

    • An over-stretched rubber band that doesn’t fling back the way it normally does.

Hypertrophic Cardiomyopathy Etiology

  • Characterized by left ventricular hypertrophy, thickening, impacting heart's ability to pump efficiently.

    • The muscle is overworked, causing this growth/hypertrophy.