Feline Cardiomyopathy Overview
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Questions and Answers

Which of the following is a characteristic of heart failure in cats that differs from dogs?

  • Myocardial ischemia is more common in cats (correct)
  • Increased myocardial O2 consumption/decreased perfusion à myocardial ischemia
  • Thickened, noncompliant ventricular wallsà diastolic dysfunction
  • Diastolic dysfunction à increased LA pressureà CHF

    • What is the most likely reason for a cat with HCM to develop a murmur?

  • Increased LA pressure à congestion (pulmonary edema, pleural effusion, pericardial effusion)
  • Geometric changes in the ventricle and papillary muscles à MR (correct)
  • Increased myocardial O2 consumption/decreased perfusion à myocardial ischemia
  • Decreased cardiac output from reduced diastolic filling

    • Which of the following is a clinical sign that may be present in a decompensated cat with HCM?

  • Sternal or parasternal murmur
  • Femoral pulse deficits
  • Cyanosis
  • All of the above (correct)

    • What is the primary pathological process underlying HCM?

    <p>Thickening of the heart muscle walls (B)</p> Signup and view all the answers

    What is the primary consequence of diastolic dysfunction in HCM?

    <p>Increased left atrial pressure (B)</p> Signup and view all the answers

    What is the most common type of feline cardiomyopathy?

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

    What is a possible cause of secondary cardiomyopathy in cats?

    <p>Hyperthyroidism (A)</p> Signup and view all the answers

    What is the likely cause of Fernando's tachypnea?

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

    What physical exam finding would likely NOT be present in a cat with cardiomyopathy?

    <p>Bradycardia (D)</p> Signup and view all the answers

    What is NOT a primary cardiomyopathy in cats?

    <p>Hyperthyroidism (A)</p> Signup and view all the answers

    Which diagnostic test is NOT typically used to diagnose cardiomyopathy in cats?

    <p>Blood glucose test (A)</p> Signup and view all the answers

    What is a possible differential diagnosis for a cat with congestive heart failure?

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

    What is the most common form of heart disease in cats?

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

    Which sign is considered frequent in dogs but very rare in cats with cardiac disease?

    <p>Cough (D)</p> Signup and view all the answers

    Which genetic mutations are associated with hypertrophic cardiomyopathy (HCM) in cats?

    <p>MYBPC3 – A31P, R820W (D)</p> Signup and view all the answers

    Which echocardiographic finding is associated with left ventricular (LV) concentric hypertrophy?

    <p>Systemic hypertension (D)</p> Signup and view all the answers

    What is often necessary for a definitive diagnosis of cardiac disease in cats?

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

    What is indicated for immediate therapy in congestive heart failure?

    <p>IV furosemide to decrease preload (A)</p> Signup and view all the answers

    Which medication is used as an inodilator in chronic congestive heart failure therapy?

    <p>Pimobendan (A)</p> Signup and view all the answers

    What is the most common site for an arterial thromboembolism in cats?

    <p>Terminal abdominal aorta (D)</p> Signup and view all the answers

    What are the 5 P’s associated with arterial thromboembolism?

    <p>Pain, pulselessness, pallor, paresis, polar (A)</p> Signup and view all the answers

    Which condition is characterized by left ventricular dilation and systolic dysfunction?

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

    What diagnostic tool is 100% specific in distinguishing healthy cats from those with cardiomyopathy?

    <p>NT-proBNP testing (B)</p> Signup and view all the answers

    Which of the following is NOT a common clinical sign of renal or splanchnic infarction?

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

    Which of the following is an adjunct therapy in the management of congestive heart failure, focused on antagonizing aldosterone?

    <p>Spironolactone (D)</p> Signup and view all the answers

    Which clinical sign is associated with reperfusion injury following arterial thromboembolism?

    <p>Ischemic pain (D)</p> Signup and view all the answers

    What does the presence of spontaneous echogenic contrast (smoke) indicate?

    <p>Possible thrombus formation (B)</p> Signup and view all the answers

    Study Notes

    Feline Cardiomyopathy

    • Feline cardiomyopathy (CM) is a primary disease of the cardiac muscle.
    • Hypertrophic cardiomyopathy (HCM) is the most common type of feline CM.
    • HCM involves thickening of the ventricular walls, typically the left ventricle (LV) wall and interventricular septum (IVS).
    • Papillary hypertrophy may occur, potentially asymmetrically.
    • Left atrial (LA) enlargement is a common finding.
    • HCM pathophysiology leads to diastolic dysfunction due to thickened and noncompliant ventricular walls, reduced diastolic filling, and decreased cardiac output.
    • Congestive heart failure (CHF) results from increased LA pressure due to diastolic dysfunction.
    • Clinical signs of HCM may include murmur (typically sternal or parasternal), gallop sound, arrhythmias, and femoral pulse deficits.
    • In decompensated cases, clinical signs include panting, tachypnea, dyspnea, cyanosis, distended jugular veins, and crackles or muffled lung sounds.

    Learning Objectives

    • Students should be able to describe the pathophysiology of hypertrophic cardiomyopathy and how it leads to heart failure.
    • Learning objectives include diagnostic testing, primary and secondary feline cardiomyopathies, differential diagnoses, clinical signs (with and without CHF), and suitable treatments for CHF and arterial thromboembolism.

    Case Study: Fernando

    • Fernando is a 10-year-old male domestic short-haired cat (DSH) with a 2-week history of lethargy and decreased activity accompanied by a 48-hour history of tachypnea.
      • The cat's physical exam indicates rapid respiratory rate (80 breaths/min), rapid heart rate (220 beats/min), gallop sound, pale pink mucous membranes, prolonged capillary refill time (~2 seconds), distended jugular veins, and bilateral crackles.
    • The presence of a systolic murmur in the left parasternal region and strong, synchronous femoral pulses suggest potential heart issues.

    Differential Diagnoses for Heart Failure

    • Students should understand the differential diagnoses of heart failure in this cat. (The provided text does not specify these diagnoses).

    Radiographic and Echocardiographic Abnormalities

    • Students should be able to interpret radiographic and echocardiographic findings for feline cardiac disease. This includes recognizing signs suggestive of generalized cardiomegaly, left atrial enlargement, left ventricular enlargement, CHF, distended pulmonary veins, interstitial and alveolar infiltrates, and pleural effusion.
    • Echocardiographic findings to look for include LV wall and septal thickening, possible LVOT obstruction, LA enlargement, and presence of a thrombus.
    • Echocardiography is beneficial for determining differences between systemic hypertension and hyperthyroid heart disease as differentials for LV concentric hypertrophy.
    • Additional considerations include NT-proBNP measurements, with data on normal and occult cardiomyopathy cases.

    Feline Cardiomyopathies

    • Primary CMs affect the cardiac muscle directly and include HCM, restrictive cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and unspecified forms.
    • Secondary CMs affect the heart due to other systemic conditions, such as hyperthyroidism, systemic hypertension, dietary factors, and acromegaly.

    Hypertrophic Cardiomyopathy (HCM) - Pathology

    • HCM is the most common feline CM.
    • Ventricular thickening characterizes HCM with typically affecting the left ventricular wall and interventricular septum.
    • The presence of asymmetric hypertrophy and left atrial enlargement suggests HCM.

    HCM Pathophysiology

    • HCM patients show thickened and stiffer ventricular walls. These characteristics lead to diastolic dysfunction and reduced cardiac output.
    • Consequent increase in left atrial pressure results in various symptoms and complications, including congestion (pulmonary edema, pleural effusion, and pericardial effusion), increased myocardial oxygen consumption, and decreased perfusion.
    • Obstruction of the left ventricular outflow tract may also occur.

    Clinical Findings - HCM

    • Compensated HCM may exhibit only a murmur.
    • Decompensated HCM may present clinical signs like panting, rapid breathing, pale mucous membranes, cyanosis, distended jugular veins, crackles or muffled lung sounds, and evidence of arterial thromboembolism.

    Dog vs. Cat Cardiac Disease

    • Dogs often present with primary valvular disease, frequent coughing, and gradually worsening signs of heart failure.
    • Cats are more likely to have cardiomyopathies with less frequent coughing, and signs appearing acutely.

    Normal Feline Radiographs

    • Normal VHS ranges from 7.75 to 8.0.
    • Heart size is generally 2.5 to 3.5 intercostal spaces (ICS).

    Radiographic Findings (CHF)

    • CHF in feline patients typically displays cardiomegaly (enlarged heart), left atrium enlargement, left ventricular enlargement, distended pulmonary veins, interstitial and alveolar infiltrates, pleural effusion, and in some cases, rare ascites.

    Electrocardiography

    • Electrocardiography (ECG) evaluation should encompass conduction abnormalities, axis shifts, and signs of chamber enlargement.

    Genetics - HCM

    • Maine Coon and Ragdoll cats have elevated HCM risk.
    • MYBPC3 gene mutations, such as A31P and R820W are associated with this disease.

    Echocardiography Differentials

    • Systemic hypertension and hyperthyroid heart disease are differentials for LV concentric hypertrophy.
    • Blood pressure measurement and obtaining T4 thyroid hormone levels are necessary for diagnosis of systemic hypertension and hyperthyroid heart disease.

    Systolic Anterior Motion (SAM)

    • SAM occurs in HCM patients and can lead to mitral regurgitation due to left ventricular outflow tract (LVOT) obstruction.

    Normal Aortic Outflow Profile vs. LVOT Obstruction

    • Study the normal aortic outflow profile versus LVOT obstruction which is relevant for diagnosis.

    Acute Therapy - Congestive Heart Failure

    • Oxygen supplementation can help, especially for acute CHF.
    • Infusion of furosemide decreases pre-load.
    • Pimobendan and dobutamine can manage CHF through contractility enhancement.
    • Sedation is an option if appropriate.
    • Thoracocentesis treats pleural effusion.

    Chronic CHF Therapy

    • Furosemide (loop diuretic), ACE inhibitors (enalapril or benazepril), and pimobendan (inodilator) for long-term CHF management.
    • Spironolactone (aldosterone antagonist) can also be used if needed.
    • Discuss the appropriate combination of medications and monitoring criteria for optimal treatment.

    Follow-up

    • Regular follow-up visits are essential for feline CM diagnosis and management. This involves rechecks (5-7 days), thoracic radiographs, renal panels, blood pressure measurements.

    Additional Considerations (NT-proBNP)

    • NT-proBNP measurements can aid in differentiating between healthy and diseased animals with 100% specificity. Normal level values versus those associated with occult cardiomyopathy should be noted.

    Feline CM Phenotypes and Definitions

    • HCM, RCM, DCM, Arrhythmogenic Cardiomyopathy (ACM) and mixed phenotypes are classified according to their structural and functional characteristics.
    • Understanding these classifications and their defining morphological and functional characteristics to support diagnosis and treatment decisions.

    RCM - Myocardial Form and End-Stage HCM

    • RCM (Myocardial form) shows normal wall thickness, atrial enlargement, and diastolic dysfunction.
    • End-stage HCM exhibits potential normal walls, dilated chambers, and myocardial infarction (MI).

    Dilated Cardiomyopathy (DCM)

    • DCM shows left ventricular dilation and systolic dysfunction.
    • Taurine deficiency is a secondary cause of DCM.

    CM Sequelae (Feline Arterial Thromboembolism [FATE])

    • FATE is a potential complication of CM characterized by arterial thromboembolism.
    • Damaged cardiac endothelium and intracardiac blood stasis are precursors to arterial thrombus formation that can lead to distal blood supply interruption.

    FATE - Pathophysiology

    • Damaged cardiac endothelium, hypercoagulable states, and intracardiac blood stasis are components of FATE pathophysiology.
    • Embolized thrombi disrupt peripheral vasculature and distal blood supply which leads to ischemia-induced necrosis of organs or muscles and potential acute pain and reperfusion injuries..

    FATE - Clinical Presentation

    • The clinical presentations of FATE may vary but may include pain, pulselessness, pallor, paresis, and cold extremities.
    • The clinical signs associated with a particular affected limb may become more apparent as the disease progresses.
    • Additional signs may include hypothermia, murmurs, gallop rhythms, and arrhythmias, indicating potential systemic involvement of the disease.

    ATE (Arterial Thromboembolism) Clinical Signs

    • In cases of ATE, affected cats may exhibit limb weakness, pain, pulse loss, cold or pale extremities, partial or complete loss of function in the affected limb, and often other systemic effects as severe cases develop.
    • Reestablishment of the collateral vascular network, dissolution of the embolus, and recanalization of obstructed aorta are key recovery processes.
    • Chronic complications, including self-mutilation, limb necrosis, and amputation may be necessary in severe cases.

    ATE - Renal or Splanchnic Clinical Signs

    • Renal ATE involves acute kidney injury (AKI) with potential pain, decreased blood pressure, stupor, seizures, and even sudden death.
    • Splanchnic ATE includes severe abdominal pain, vomiting, and may also present with neurological signs.

    Additional Clinical Signs

    • Additional clinical signs which may accompany advanced cases of cardiomyopathy may include hypothermia, murmur, gallop, arrhythmia, and congestive heart failure (reported in as many as 60% of cases).

    Diagnostic Tests

    • Chemistry panels may reveal hyperglycemia (caused by stress), hypoglycemia (if limb affected), azotemia (hypoperfusion), increased creatine kinase (CK), increased aspartate aminotransferase (AST)/alanine aminotransferase (ALT), and hyperkalemia.
    • Chest radiographs assist in identifying congestive heart failure.
    • Echocardiograms evaluate heart size and content, especially left atrial (LA) enlargement.

    Prevention and Management

    • Prevention of FATE involves managing CM, which includes a variety of therapies, such as improved survival rates with a singular affected limb. Prevention may include medications like clopidogrel, which has been shown to improve ATE outcomes.
    • Manage pain, maintain hydration/perfusion (judiciously), manage congestive heart failure, and consider thrombolytic therapy and anticoagulant therapy as needed.

    Prognosis

    • The prognosis for feline CM, especially FATE, is generally guarded.
    • Survival rates are usually between 33% and 39%. Single limb involvement may improve survival compared to bilateral limb involvement, as seen with pelvic limb infarction.
    • Acute prognosis often becomes clearer with 24-72 hours of observing the condition.

    Anticoagulants

    • Unfractionated heparin (UH) and low molecular weight heparin (LMWH) including dalteparin and enoxaparin are used for this purpose.

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    Description

    This quiz provides an overview of feline cardiomyopathy, focusing on hypertrophic cardiomyopathy (HCM). Learn about the pathophysiology, clinical signs, and complications associated with this common cardiac disease in cats. Test your knowledge on the condition and its effects on feline health.

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