Congenital Heart Disease in Animals
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Questions and Answers

What is the most common cause of cyanotic heart disease in dogs and cats?

  • Patent ductus arteriosus
  • Ventricular septal defect
  • Eisenmenger's syndrome
  • Tetralogy of Fallot (correct)

    • What happens to the shunting of blood flow in Eisenmenger's Syndrome?

  • The shunt reverses from left-to-right to right-to-left (correct)
  • The shunt is bidirectional
  • The shunt is completely blocked
  • The shunt remains left-to-right

    • What is the most common congenital heart disease diagnosed in cyanotic dogs?

  • Patent ductus arteriosus (PDA)
  • Eisenmenger's Syndrome
  • Ventricular septal defect (VSD)
  • Tetralogy of Fallot (correct)

    • Which of the following is NOT a characteristic feature of Tetralogy of Fallot?

    <p>Atrial septal defect (C)</p> Signup and view all the answers

    What is the primary function of a modified Blalock-Taussig shunt?

    <p>To increase blood flow to the lungs (B)</p> Signup and view all the answers

    What is the most common long-term treatment option for Tetralogy of Fallot?

    <p>Cardiac bypass surgery (B)</p> Signup and view all the answers

    Which of the following conditions can lead to Eisenmenger's Syndrome?

    <p>All of the above (D)</p> Signup and view all the answers

    What is the expected clinical finding in a patient with Tetralogy of Fallot?

    <p>Cyanosis (B)</p> Signup and view all the answers

    What medical therapy is commonly used in patients with Tetralogy of Fallot?

    <p>Intermittent phlebotomy (B)</p> Signup and view all the answers

    What is the most likely reason why patients with congenital heart disease may not show signs until adulthood?

    <p>The defect is small and only becomes significant with age (B)</p> Signup and view all the answers

    What is the most important factor in determining the prognosis of a patient with congenital heart disease?

    <p>All of the above (D)</p> Signup and view all the answers

    What is the common prevalence rate of congenital heart disease in dogs examined at referral hospitals?

    <p>0.5 - 0.9% (A)</p> Signup and view all the answers

    What is the primary characteristic of Eisenmenger's Syndrome?

    <p>Reversal of a normally left-to-right shunting lesion. (A)</p> Signup and view all the answers

    What is the most direct consequence of pulmonary stenosis in Tetralogy of Fallot?

    <p>Decreased blood flow to the lungs (A)</p> Signup and view all the answers

    What is the primary purpose of a modified Blalock-Taussig shunt in a patient with Tetralogy of Fallot?

    <p>To increase blood flow to the lungs (A)</p> Signup and view all the answers

    Which of the following statements is TRUE regarding long-term prognosis for patients with Tetralogy of Fallot?

    <p>Most patients survive years with intermittent phlebotomy. (C)</p> Signup and view all the answers

    What is the most common reason why a young patient with Tetralogy of Fallot might experience cyanosis?

    <p>Decreased blood flow to the lungs (B)</p> Signup and view all the answers

    Which of the following is a common clinical presentation of Tetralogy of Fallot?

    <p>Asymptomatic but signs of severe exercise intolerance (D)</p> Signup and view all the answers

    Why might a young animal with congenital heart disease appear polycythemic?

    <p>Increased production of red blood cells due to insufficient oxygenation. (A)</p> Signup and view all the answers

    Which of the following is a likely reason why a patient with a congenital heart defect may not present with clinical signs until adulthood?

    <p>All of the above (D)</p> Signup and view all the answers

    Which congenital heart disease is commonly associated with a left-to-right shunt in young animals?

    <p>Ventricular septal defect (A)</p> Signup and view all the answers

    What is a significant cardiovascular change that typically occurs immediately after birth?

    <p>Collapse of the ductus arteriosus (D)</p> Signup and view all the answers

    In Tetralogy of Fallot, which anatomical feature is responsible for the cyanotic symptoms?

    <p>Overriding aorta (C)</p> Signup and view all the answers

    What characterizes Eisenmenger's Syndrome in congenital heart disease?

    <p>Reversed left-to-right shunt (B)</p> Signup and view all the answers

    What is the primary role of the modified Blalock-Taussig shunt in treating Tetralogy of Fallot?

    <p>To increase pulmonary blood flow (D)</p> Signup and view all the answers

    Which anatomical feature contributes to the severity of cyanosis in patients with Tetralogy of Fallot?

    <p>Severity of pulmonary stenosis (C)</p> Signup and view all the answers

    What is a common clinical finding associated with congenital heart disease in young animals?

    <p>Exercise intolerance (B)</p> Signup and view all the answers

    Which of the following factors is crucial in determining the prognosis of congenital heart disease?

    <p>Type and severity of malformation (A)</p> Signup and view all the answers

    Which congenital heart defect is least likely to be asymptomatic in early stages?

    <p>Tetralogy of Fallot (B)</p> Signup and view all the answers

    What is a primary challenge in diagnosing congenital heart disease?

    <p>Delayed presentation of clinical signs (D)</p> Signup and view all the answers

    Flashcards

    Congenital Heart Disease (CHD)

    Defect in cardiac structure present at birth, may be inherited or spontaneous.

    Eisenmenger’s Syndrome

    Reversal of a left-to-right shunt due to higher right-sided pressures, often from pulmonary hypertension.

    Tetralogy of Fallot

    Most common cyanotic heart disease with four specific abnormalities affecting blood flow.

    Pulmonary Stenosis

    Narrowing at the outflow from the right ventricle to the pulmonary artery, affecting blood flow.

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    Symptoms of Tetralogy of Fallot

    Signs range from being asymptomatic to severe exercise intolerance, cyanosis, or seizures.

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    Diagnosis of CHD

    Specific defects can be identified using echocardiographic examination.

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    Please refer to a cardiologist

    Important for thorough evaluation and management of suspected congenital heart defects.

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    Prognosis for CHD

    Dependent on type, severity of malformation and treatment options available.

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    Treatment options for CHD

    May include medical therapy, phlebotomy, or surgery to manage defects.

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    Polycythemia in CHD

    Condition where patients frequently have increased red blood cells due to chronic hypoxia.

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    Post-natal cardiovascular changes

    Major changes in heart and circulation after birth.

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    Congenital heart diseases in dogs

    Most common congenital defects in dogs, e.g., Tetralogy of Fallot.

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    Congenital heart diseases in cats

    Lower prevalence of congenital heart diseases in cats compared to dogs.

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    Cardiac examination findings

    Clinical signs that may indicate congenital heart disease.

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    Survival rate of modified Blalock-Taussig shunt

    83% survival rate post-surgery with improved clinical signs.

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    Signs of Eisenmenger’s syndrome

    Reversion of typical shunt flow due to high right heart pressure.

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    Right ventricular hypertrophy

    Thickening of the heart muscle due to increased workload.

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    Treatment for severe CHD cases

    Includes surgery or long-term medical management.

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    Clinical findings in Tetralogy of Fallot

    Cyanosis and exercise intolerance; murmur typically present.

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    Referral to a cardiologist

    Needed for thorough evaluation of congenital heart defects.

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    Clinical findings of CHD

    Signs that suggest congenital heart disease in animals.

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    Major cardiovascular changes post-birth

    Significant changes in heart structure and function occur immediately after birth.

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    Patent Ductus Arteriosus (PDA)

    Failure of the ductus arteriosus to close after birth, leading to left-to-right shunt.

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    Ventricular Septal Defect (VSD)

    A hole in the septum dividing the ventricles, causing abnormal blood flow.

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    Outflow tract stenoses

    Narrowing of pathways from the heart, affecting blood flow to lungs or body.

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    Cyanosis in Tetralogy of Fallot

    A bluish discoloration of the skin indicating insufficient oxygen in the blood.

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    Reversed shunt in Eisenmenger's Syndrome

    Normal left-to-right blood flow turns into right-to-left due to high pressures.

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    Prognosis for Tetralogy of Fallot

    Long-term outlook is poor; many may not survive past early childhood without intervention.

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    Modified Blalock-Taussig shunt

    A surgical procedure to improve blood flow in patients with specific heart defects.

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    Exercise intolerance signs

    Reduced ability to exercise often due to inadequate blood oxygenation.

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    Major cardiovascular changes post-natal

    Significant modifications in heart and circulation immediately after birth.

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    Common congenital heart diseases in horses

    Defects such as VSD and PDA that affect equines.

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    Common congenital heart diseases in cattle

    Defects like pulmonary hypertension and PDA present in bovines.

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    Clinical findings in congenital heart disease

    Signs like murmurs, cyanosis, and exercise intolerance indicating heart issues.

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    Polycythemia in congenital heart disease

    Increased red blood cell count due to chronic low oxygen levels.

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    Pathophysiology of Tetralogy of Fallot

    Involves four abnormalities reducing blood flow and causing cyanosis.

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    Expected clinical findings in VSD

    Murmur present; could result in exercise intolerance and heart failure.

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    Treatment approaches for congenital heart diseases

    Includes meds, surgical interventions, or specialized procedures.

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    Signs of severe exercise intolerance

    Symptoms like dyspnea, fainting, or weakness after exertion.

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    Common congenital heart diseases in camelids

    Congenital defects affecting llamas or alpacas, less studied but exist.

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    Structural heart disease indication

    Evaluation of heart murmurs in young animals to assess risk of structural defects.

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    Fetal vs Adult circulatory systems

    The circulatory system in fetuses differs significantly from that of adults.

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    Cardiovascular changes post-birth

    Major physiological adaptations occur in the heart and circulation immediately after birth.

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    Common congenital heart diseases in dogs

    Includes defects like Tetralogy of Fallot and patent ductus arteriosus.

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    Eisenmenger’s syndrome mechanism

    Increased right-sided pressure causes reversal of left-to-right shunt in heart defects.

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    Clinical signs of Tetralogy of Fallot

    Symptoms can range from no symptoms to severe outcomes like seizures and cyanosis.

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    Prognosis aspects for congenital heart defects

    Survival and quality of life depend on type and severity of heart malformations.

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    Surgical options in Tetralogy of Fallot

    Limited surgeries include cardiac bypass or modifications to improve hemodynamics.

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    Treatment goals for CHD

    Aim for prompt detection and referring to a specialist for management of congenital heart defects.

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    Study Notes

    Congenital Heart Disease

    • Congenital heart disease (CHD) is a defect in the heart's structure present at birth.
    • CHD can be inherited or develop spontaneously.
    • Risk factors for CHD include genetic mutations, toxins, infections, environmental factors, drug-related factors, nutritional factors, and are often developmental anomalies.
    • CHD is a common cause of heart disease in young animals.
    • CHD prevalence in dogs and cats ranges from 0.5-0.9% for dogs and 0.05% for cats.
    • CHD prevalence is <10% of all diagnosed heart disease in dogs and cats.
    • CHD affects large animals, including horses (0.7-0.8%) and cattle (<0.2%).
    • CHD prevalence is 1.5% for alpacas and 3.6% for referral hospitals.

    Learning Objectives

    • Identify clinical signs suggestive of CHD, including physical examination findings (breed/family history, history/clinical signs, physical findings).
    • Differentiate between innocent and pathological heart murmurs in young animals; determining if a heart murmur is associated with structural heart disease.
    • Compare and contrast fetal and adult circulatory systems.
    • List major cardiovascular changes in the immediate postnatal period.
    • List common CHD types in dogs, cats, horses, cattle, and camelids.
    • Describe pathophysiology, clinical findings, and treatment strategies for specific CHDs (e.g., PDA, VSD, Tetralogy of Fallot).

    Definition

    • CHD is a defect in the cardiac structure present at birth.
    • May be inherited; may develop spontaneously.
    • Genetic mutations, toxins, infections, environmental factors, drug-related factors, nutritional factors can play a role, and are often developmental anomalies.

    Prevalence

    • Dogs and cats represent approximately 0.5-0.9% (dogs) and 0.05% (cats) of referral hospitals, with CHD accounting for less than 10% of all diagnosed heart disease.
    • Large animals affected are approximately 0.7-0.8% of horses and <0.2% of cattle presented for necropsy.
    • Prevalence is 1.5% in alpacas and 3.6% in referral hospitals.

    When To Suspect CHD

    • Breed/family history of CHD
    • History/clinical signs: Failure to thrive, poor exercise tolerance, syncope, difficulty breathing, abdominal distension, and sudden death
    • Suggestive physical examination findings: Heart murmur, arrhythmia, cyanotic mucous membranes, abnormal jugular venous or peripheral arterial pulses.

    Heart Murmurs In Young Animals

    • Innocent/Physiological: Softer or absent at rest, increases with excitement/exercise, soft murmur grade 1–2/6, single, no other associated abnormal heart sounds
    • Pathological: Can be heard at all times, loud murmur grade 3/6 or louder, associated clinical signs or physical exam findings like cyanosis, jugular venous distention/pulsation, exercise intolerance, difficult breathing, ascites, murmur can be systolic, diastolic, or continuous; persists beyond 4–6 months of age.

    Review: Normal Fetal Circulation

    • Ductus venosus: Connects umbilical vein to caudal vena cava.
    • Foramen ovale: Small opening in septum between right and left atria
    • Ductus arteriosus: Connects pulmonary artery to descending aorta.

    Review: Normal Postnatal Cardiovascular Changes

    • Pulmonary circulation resistance decreases as lungs inflate.
    • Systemic circulation resistance increases due to loss of placental circulation.
    • Three fetal shunts (ductus venosus, foramen ovale, and ductus arteriosus) close postnatally due to changes in vascular pressure, oxygen tension, and loss of placental prostaglandins.

    Things To Remember

    • Blood flow is typically high pressure to low pressure.
    • The heart responds to stress through concentric hypertrophy (wall thickening) responding to increased end-systolic wall stress or eccentric hypertrophy (chamber dilation) responding to increased end-diastolic wall stress.

    Classification Of Congenital Heart Lesions

    • Acyanotic CHD: Left-to-right shunts (PDA, VSD, ASD), obstruction to ventricular outflow (PS, SAS), or regurgitant valve lesions (mitral/tricuspid valve dysplasia).
    • Cyanotic CHD: Right-to-left shunts (Tetralogy of Fallot), Eisenmenger's syndrome, reversed PDA, and reversed ventricular septal defect (VSD).

    Most Common Defect By Species

    • Specific congenital heart defects are more common in some species (e.g., PDA in dogs). Specific defects and their frequencies are listed for different species.

    Pathophysiology of Left-To-Right Shunts

    • Communication between pulmonary veins/left heart and systemic arterial circulation/systemic venous circulation/ Right heart/pulmonary arteries.
    • Re-circulation of oxygen-rich blood leads to volume overload and eccentric hypertrophy of the affected heart structures.
    • Most common L-to-R shunts: PDA, ventricular and atrial septal defects.

    Patent Ductus Arteriosus (PDA)

    • Failure of ductus arteriosus to close after birth.
    • Normal closure occurs in minutes to hours for dogs/cats, and 3-4 days for horses.
    • Anatomic closure occurs within 1 month.

    Patent Ductus Arteriosus (PDA): Clinical Findings

    • “Wind blowing through a tunnel”, “machinery” murmur, grade/intensity is typically IV–VI/VI, palpable thrill common, location is left heart base, and timing is continuous.

    Patent Ductus Arteriosus (PDA): Prognosis and Recommendations

    • If untreated, 65% of dogs die of heart failure within one year.
    • Surgical closure is highly curative.
    • Screen relatives of affected animals; do not breed affected animals; if a continuous murmur is heard, don't monitor, refer to a cardiologist.

    Ventricular Septal Defect (VSD)

    • Defect in the interventricular septum (IVS) allowing direct communication of ventricles, is common in large animals and cats.
    • Majority are located in the basilar/upper portion of the IVS ("perimembranous").

    Ventricular Septal Defect (VSD): Clinical Findings

    • Grade/intensity: Variable, smaller VSD = louder murmur
    • Location: Right heart (apex or base, depending on location of VSD)
    • Timing: Systolic

    Ventricular Septal Defect (VSD): Prognosis and Recommendations

    • Clinical picture/prognosis depends on the size/volume of the shunt..—most are small and well-tolerated; moderate/large shunts may require treatment for CHF; small defects-no intervention.
    • Surgical closure of larger defects or minimally invasive occlusion are possible in some cases but not widely available.

    Lesions causing obstruction (stenosis) of ventricular outflow

    • High-pressure distal to the obstruction leads to concentric hypertrophy of the ventricles.
    • Low-pressure distal to the obstruction, will cause high-velocity, turbulent flow causing an audible murmur and post-stenotic dilatation.
    • Narrowing of the ventricular outflow tract increases resistance to blood flow.

    Potential Consequences of Outflow Tract Stenosis

    • Congestive heart failure is one of the more frequent heart issues found more commonly in RV, rather than LV.
    • Sudden cardiac death
    • Lethal ventricular arrhythmias due to fibrosis/ischemia
    • “Critical” stenosis: Flow too low to satisfy body’s demands (syncope, weakness, lethargy).
    • The risk of complications increases with lesion severity. More details on pressure gradient ranges and their correlations to clinical severity are included.

    Obstruction (Stenosis) of Ventricular Outflow: Clinical Features

    • Murmur: Variable intensity/grade, located at the left heart base; timing is systolic.
    • Femoral pulses usually normal for RV obstruction; can be reduced in LV obstruction if stenosis is severe enough.

    Obstruction (Stenosis) of Ventricular Outflow: Species-Specific Clinical Features

    • Most animals showing CHD will be asymptomatic for an extended period; the owner may notice exertional fatigue, syncope, or other signs of CHF in those with severe stenosis. Specific clinical features for common types of outflow obstruction are included.

    Obstruction (Stenosis) of Ventricular Outflow: Clinical Management

    • B1-adrenergic blockers are frequently utilized for moderate-severe stenosis to reduce myocardial oxygen demand.
    • Antiarrhythmic medications are used as well.
    • Percutaneous balloon valvuloplasty for pulmonic stenosis, although not as frequently utilized for subaortic stenosis.
    • Breeding considerations vary based on severity, as significant defects greatly reduce the chances of survival and proper heart function.

    Pathology of Right-to-Left Shunts

    • Abnormal communication between systemic venous circulation/right heart/pulmonary arteries and pulmonary veins/left heart/systemic arterial circulation.
    • Oxygenated blood bypasses the lungs, so the systemic circulation doesn't receive enough oxygen.
    • Cyanosis is a visible sign when PaO2 < 40mm Hg, which may result in polycythemia.
    • Common examples include Tetralogy of Fallot, Eisenmenger's syndrome (including reversed PDA and reversed VSD). More specific details on the pathology of each are included.

    Eisenmenger's Syndrome

    • Reversal of normal left-to-right heart shunt due to increased right-sided pressures as a result of pulmonary hypertension.
    • Shunt reverses when pulmonary vascular resistance exceeds systemic vascular resistance.
    • Common issue occurring in instances of PDA, VSD, or ASD.

    Tetralogy of Fallot

    • Most common cyanotic heart disease in animals.
    • Upper interventricular septum malformation leads to four abnormalities.

    Tetralogy of Fallot: Clinical Features

    • Asymptomatic or signs of severe exercise intolerance syncope and seizures.
    • Cyanosis is present in 90% of affected animals at rest; the cyanosis worsens during exercise.
    • A systolic murmur is frequently present left basilar location.
    • Pulses are usually normal.

    Tetralogy of Fallot: Prognosis and Recommendations

    • Medical therapy: Intermittent phlebotomy and exercise restriction.
    • Surgical options: Palliative systemic-to-pulmonary shunts (e.g., modified Blalock-Taussig shunt, subclavian artery-to-pulmonary artery conduit) or cardiac bypass. Specific surgical options and success rates are included.

    Take Home Points

    • CHD severity ranges from trivial (well-tolerated) to life-threatening.
    • CHD is the most common type of heart disease in young animals, although signs may not be noticed until adulthood.
    • Diagnosis can be made through echocardiography.
    • Prognosis is heavily dependent on the type and severity, as well as availability of treatment options.
    • Prompt recognition from a veterinarian. Referral to a cardiologist for the most appropriate diagnosis is often required.

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    Congenital Heart Disease Student PDF

    Description

    This quiz covers congenital heart disease (CHD), a structural defect in the heart present at birth, affecting various animals like dogs, cats, and large animals. It focuses on identifying clinical signs, differentiating heart murmurs, and understanding prevalence across species. Test your knowledge on the risk factors and implications of CHD in veterinary practice.

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