Dilated Cardiomyopathy Overview
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Questions and Answers

What is the most common viral cause of myocarditis?

  • HIV
  • Coxsackievirus A & B (correct)
  • Influenza virus
  • ECHO virus

    • Which type of myocarditis is characterized by a widespread inflammatory infiltrate and poor prognosis?

  • Lymphocytic myocarditis
  • Giant cell myocarditis (correct)
  • Chagas disease myocarditis
  • Hypersensitivity myocarditis

    • What is a potential result of myocarditis when healing occurs?

  • Reversal of all symptoms
  • Complete myocardial regeneration
  • Development of dilated cardiomyopathy (correct)
  • Increased exercise tolerance

    • What is a common symptom of chronic heart failure that may develop due to heart enlargement?

    <p>Pulmonary venous congestion</p> Signup and view all the answers

    What type of infiltrate is typically seen in hypersensitivity myocarditis?

    <p>Lymphocytes and macrophages</p> Signup and view all the answers

    What leads to the 'apical ballooning' commonly seen in the left ventricular apex?

    <p>Calcium overload or focal vasoconstriction</p> Signup and view all the answers

    What role does aldosterone play in heart failure progression?

    <p>Promotes cardiac remodeling and fibrosis</p> Signup and view all the answers

    Which complication is likely to arise from left atrial dilation due to mitral regurgitation?

    <p>Atrial fibrillation</p> Signup and view all the answers

    Which of the following is NOT a typical clinical feature of dilated cardiomyopathy (DCM)?

    <p>Elevated ejection fraction</p> Signup and view all the answers

    What is one of the most common etiologies of dilated cardiomyopathy?

    <p>Idiopathic causes</p> Signup and view all the answers

    What is a characteristic feature of dilated cardiomyopathy?

    <p>Pathological features include ventricular dilation</p> Signup and view all the answers

    Which of the following best describes hypertrophic cardiomyopathy?

    <p>Characterized by increased left ventricular wall thickness</p> Signup and view all the answers

    Which of the following applies to arrhythmogenic right ventricular cardiomyopathy?

    <p>It is primarily genetic in origin</p> Signup and view all the answers

    In the context of dilated cardiomyopathy, which is a potential etiology?

    <p>Alcohol and viral infections</p> Signup and view all the answers

    What histological finding is most commonly associated with hypertrophic cardiomyopathy?

    <p>Clustered abnormal myocytes</p> Signup and view all the answers

    What sequence of events leads to impaired myocardial perfusion in hypertrophic cardiomyopathy (HCM)?

    <p>Increased wall stress leads to increased myocardial O2 demand, squeezing down on small coronary branches.</p> Signup and view all the answers

    How does lightheadedness relate to cardiovascular dynamics when standing?

    <p>Standing causes blood pooling in the legs, leading to decreased left ventricular return.</p> Signup and view all the answers

    What is a consequence of increased physical exertion in individuals with HCM?

    <p>It increases force of contraction, worsening obstruction and causing a drop in cardiac output.</p> Signup and view all the answers

    What effect do arrhythmias have on HCM symptoms?

    <p>Arrhythmias can exacerbate symptoms like atrial fibrillation and lead to syncope.</p> Signup and view all the answers

    What is the relationship between increased left ventricular (LV) obstruction and preload during lightheadedness?

    <p>Decreased preload results in increased obstruction and decreased cardiac output.</p> Signup and view all the answers

    What is one of the primary characteristics of dilated cardiomyopathy (DCM)?

    <p>Marked dilation of all chambers of the heart</p> Signup and view all the answers

    Which compensatory mechanism is activated due to decreased renal perfusion in DCM?

    <p>Sympathetic nervous system activation</p> Signup and view all the answers

    What is the likely outcome of severe myocyte contractility impairment in DCM?

    <p>Enlarged ventricles</p> Signup and view all the answers

    How do the heart chambers typically change in DCM?

    <p>Chambers can be limited to dilation on one side</p> Signup and view all the answers

    What is the role of angiotensin II in the pathophysiology of DCM?

    <p>Increases end diastolic volume</p> Signup and view all the answers

    What histological finding is observed in DCM?

    <p>Markedly irregular hypertrophy of myocytes</p> Signup and view all the answers

    What does the increased stretch of myofibers in DCM lead to?

    <p>Increased myocardial oxygen demand</p> Signup and view all the answers

    Which mechanism is involved in compensating for decreased cardiac output in DCM?

    <p>Increased heart rate and contractility</p> Signup and view all the answers

    What is a potential consequence of chronic elevations in aldosterone and angiotensin II in DCM?

    <p>Cardiac remodeling and fibrosis</p> Signup and view all the answers

    What clinical feature may indicate left atrial dilation in a patient with DCM?

    <p>Heart murmur of mitral regurgitation</p> Signup and view all the answers

    Which symptom reflects pulmonary venous congestion in DCM?

    <p>Auscultatory crackles</p> Signup and view all the answers

    Which condition is a potential complication of dilated cardiomyopathy related to cardiac remodeling?

    <p>Atrial fibrillation</p> Signup and view all the answers

    What is a characteristic sign of heart failure in a patient with dilated cardiomyopathy?

    <p>Third heart sound (S3)</p> Signup and view all the answers

    What type of myocarditis may lead to chronic immune-mediated cardiac insufficiency years after the initial attack?

    <p>Chagas Disease myocarditis</p> Signup and view all the answers

    Which type of infiltration is commonly observed in giant cell myocarditis?

    <p>Multinucleate giant cells and eosinophils</p> Signup and view all the answers

    Which of the following viruses is NOT commonly associated with myocarditis?

    <p>Herpes Simplex Virus</p> Signup and view all the answers

    Which underlying mechanism is suggested to potentially cause apical ballooning in the left ventricular apex?

    <p>Calcium overload and focal vasoconstriction</p> Signup and view all the answers

    Which type of myocarditis is characterized by perivascular interstitial infiltrates primarily consisting of eosinophils?

    <p>Hypersensitivity myocarditis</p> Signup and view all the answers

    What is a direct consequence of increased wall stress in hypertrophic cardiomyopathy (HCM)?

    <p>Myocardial perfusion impairment</p> Signup and view all the answers

    How does standing affect preload and consequently left ventricular (LV) performance?

    <p>Decreased preload and reduced chamber size</p> Signup and view all the answers

    What characterizes the occurrence of syncope in individuals with HCM during physical exertion?

    <p>Outflow block from increased force of contraction</p> Signup and view all the answers

    Which factor primarily contributes to lightheadedness when a person stands up?

    <p>Decreased cerebral perfusion</p> Signup and view all the answers

    What impact do aberrant myocytes have on arrhythmias in HCM?

    <p>They cause abnormal conduction patterns</p> Signup and view all the answers

    What is the primary treatment for patients with Hypertrophic Cardiomyopathy (HCM) to manage their symptoms?

    <p>Beta blockers</p> Signup and view all the answers

    What clinical feature is best associated with the physical examination of Hypertrophic Cardiomyopathy?

    <p>S4 heart sound</p> Signup and view all the answers

    Which of the following is a common consequence of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)?

    <p>Right ventricular failure</p> Signup and view all the answers

    What is a critical consideration in the management of patients with HCM concerning physical activity?

    <p>Avoidance of strenuous exercise</p> Signup and view all the answers

    What is a characteristic pathophysiological alteration in the myocardium of patients with HCM?

    <p>Increased myocardial hypertrophy</p> Signup and view all the answers

    Which mutation is most likely responsible for the sudden collapse of the 19-year-old basketball player?

    <p>Beta-myosin heavy chain</p> Signup and view all the answers

    What is the main characteristic finding on an echocardiogram in a patient with hypertrophic cardiomyopathy?

    <p>Thickened left ventricular wall</p> Signup and view all the answers

    Which of the following cardiac conditions is most associated with ventricular tachycardia due to abnormalities in right ventricular activation?

    <p>Arrhythmogenic right ventricular cardiomyopathy</p> Signup and view all the answers

    What imaging technique can reveal abnormal right ventricular morphology in ARVC?

    <p>Non-invasive imaging</p> Signup and view all the answers

    What type of wave may indicate abnormal right ventricular activation in an EKG reading?

    <p>Epsilon wave</p> Signup and view all the answers

    Which cardiomyopathy is characterized primarily by a defect in energy transfer from mitochondria to the sarcomere?

    <p>Hypertrophic cardiomyopathy</p> Signup and view all the answers

    Which of the following is a common genetic cause of dilated cardiomyopathy?

    <p>Lamin A/C</p> Signup and view all the answers

    Which condition is NOT a typical associated factor in dilated cardiomyopathy?

    <p>Sarcomeric protein mutation</p> Signup and view all the answers

    Study Notes

    Dilated Cardiomyopathy (DCM)

    • Definition: DCM is a heart muscle disease characterized by enlarged, weakened heart chambers that struggle to pump blood effectively.
    • Etiology:
      • Idiopathic (most common)
      • Familial/Genetic
      • Inflammatory:
        • Infectious (Viral): Coxsackievirus A & B, parvovirus B19, adenovirus, ECHO, HIV, CMV, influenza
        • Nonviral: Trypanasoma cruzi (Chagas Disease), Trichinella spiralis (Trichinosis), Toxoplasma gondii (Toxoplasmosis), Borrelia burgdorferi (Lyme Disease), Corynebacterium diphtheriae (Diptheria)
      • Noninfectious: Hypersensitivity myocarditis, Giant cell myocarditis
      • Toxic: Chronic alcohol ingestion, chronic cocaine use, chemotherapeutic agents
    • Pathological Features:
      • Gross Appearance: Heavy, large, flabby heart with dilation of all chambers. May be limited to one side.
      • Microscopic Appearance:
        • Enlarged nuclei and irregular hypertrophy of myocytes
        • Attenuated, stretched, irregular, degenerated, and atrophic myocytes
        • Interstitial, endocardial, and perivascular fibrosis
    • Pathophysiology:
      • ** Impaired myocyte contractility:** Decreases ventricle stroke volume (SV) and cardiac output (CO)
      • Compensatory mechanisms:
        • Frank-Starling Mechanism: Increased end-diastolic volume (EDV) leads to increased myofiber stretch, which increases contractile force and SV.
        • Neurohormonal Activation:
          • Decreased CO results in decreased renal perfusion, triggering the renin-angiotensin-aldosterone system (RAAS) activation.
          • Sympathetic stimulation increases heart rate and contractility, further increasing CO.
        • RAAS Activation:
          • Angiotensin II increases systemic vascular resistance (SVR), making it difficult for a weakened LV to pump.
          • Aldosterone increases intravascular/EDV, leading to fluid backup and pulmonary/systemic congestion.
    • Clinical Features:
      • Slow, progressive signs/symptoms of congestive heart failure (CHF):
        • Cool extremities, low arterial pressure, tachycardia
        • Pulmonary venous congestion leading to auscultatory crackles
        • Left and upward displacement of the point of maximal impulse (PMI)
        • Enlarged heart
        • Third heart sound (S3)
      • Complications: Mitral/Tricuspid regurgitation, atrial fibrillation, mural thrombus/thromboembolism
    • Prognosis:
      • High mortality rate
      • Death typically occurs from progressive cardiac failure or arrhythmia

    Hypertrophic Cardiomyopathy (HCM)

    • A heart muscle disease characterized by thickening of the heart muscle, particularly in the left ventricle.

    • Etiology: Primarily genetic, caused by mutations in genes responsible for cardiac proteins.

    • Pathogenesis:

      • Increased wall stress: Due to increased myocardial oxygen demand.
      • Hypertrophy: Squeezes down on small coronary branches, impairing myocardial perfusion.
      • Outflow obstruction: The thickened heart muscle can obstruct blood flow from the left ventricle, leading to a reduction in CO.

    • Pathological Features:

      • Gross Appearance: Enlarged heart, particularly the left ventricle
      • Microscopic Appearance: Hypertrophic myocytes with disorganized arrangement.

    • Pathophysiology:

      • Aberrant myocytes: Within the conduction system, leading to abnormal conduction and arrhythmias.

    • Clinical Features:

      • Symptoms:
        • Chest pain
        • Dyspnea
        • Syncope
        • Arrhythmias
      • Physical exam findings:
        • Hyperdynamic precordium
        • A fourth heart sound (S4)

    • Treatment:

      • Medical: Beta-blockers, calcium channel blockers, antiarrhythmics
      • Surgical: Septal myectomy, alcohol septal ablation
      • Devices: Implantable cardioverter-defibrillator (ICD)

    Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

    • A rare heart muscle disease characterized by the replacement of heart muscle with fat and fibrous tissue.
    • Etiology: Primarily genetic, associated with mutations in genes involved in desmosome formation.
    • Pathogenesis:
      • Genetic: Leads to abnormalities in the cell-to-cell connections of heart muscle cells, making them more prone to damage and death.
      • Replacement of muscle with fat and fibrosis: This disrupts the normal electrical activity of the heart, leading to arrhythmias.
    • Clinical Features:
      • Symptoms: Arrhythmias, palpitations, syncope, sudden cardiac death
      • Physical exam findings: May have a heart murmur.

    Comparison of Dilated and Hypertrophic Cardiomyopathy

    Feature Dilated Cardiomyopathy Hypertrophic Cardiomyopathy
    Heart muscle Weak, stretched, and thin Thick, stiff
    Heart chambers Enlarged Normal or slightly enlarged
    Blood flow Reduced due to weak pumping Obstructed due to thickened heart muscle
    Symptoms Congestive heart failure, fatigue, shortness of breath Syncope, chest pain, arrhythmias
    Treatment Medications, heart transplant Medications, surgical myectomy, alcohol septal ablation

    Hypertrophic Cardiomyopathy

    • 19-year-old college student with a family history of sudden death, collapses suddenly during basketball
    • EKG shows ventricular tachycardia and ventricular fibrillation
    • Patient resuscitated and hospitalized, but dies suddenly 3 years later
    • Echocardiogram reveals thickened left ventricular wall and small chamber
    • Interventricular septum markedly thickened
    • Most likely mutation in a sarcomeric protein, causing hypertrophic cardiomyopathy

    Hypertrophic Cardiomyopathy Pathophysiology

    • Genetic condition, often inherited
    • Mutation in sarcomeric proteins leads to impaired energy transfer from mitochondria to the sarcomere
    • Results in excessive hypertrophy of the left ventricle muscle
    • Thickened ventricular septum can obstruct blood flow out of the left ventricle.
    • Impaired muscle function and blood flow can lead to arrhythmias like ventricular tachycardia and fibrillation.
    • Sudden death is a major risk due to cardiac arrhythmias.

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    Description

    This quiz covers the essential aspects of Dilated Cardiomyopathy (DCM), a condition where the heart chambers become enlarged and weakened. It includes information about its definition, etiology, pathological features, and various infectious and non-infectious causes. Test your knowledge of this significant heart disease.

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