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Classification

n Primary cardiomyopathies

u Hypertrophic

u Restrictive Update on managing feline heart u Dilated disease u Unclassified n Secondary cardiomyopathies

u Metabolic Meg Sleeper VMD, DACVIM (cardio) u Infiltrative

Gainesville, Florida u Toxic

u Inflammatory

Feline Murmurs Hypertrophic cardiomyopathy (HCM)

n The most common of the feline primary cardiomyopathies n Etiology is uncertain, but it is inherited in some feline lines and a mutation has been identified in Maine coons and Rag dolls n Prevalence of heart murmurs in overtly normal n Causes of secondary left ventricular hypertrophy must be ruled ranges from 16-44%. out to diagnose a with HCM (thyrotoxicosis, systemic n Between 25% (Bonagura 2000) and 69% (Paige et al. hypertension) 2009) of cats with murmurs on physical examination n Hypertrophic cardiomyopathy (HCM) is a primary myocardial have no echocardiographic evidence of heart disease disease that results in mild to severe thickening (concentric hypertrophy) of the left ventricle. u Global or regional

Clinical Manifestations- HCM Clinical Manifestations-HCM

n Systolic murmurs (36-72% of cats) n Sex: Male > Female n Gallop sound (33%) n Breeds: , , Persian, American and n Dyspnea (35%) , Siberian, Norwegian forest cats, n Syncope (4%) , Sphinx, , Himalayan, n Other (not cardiac specific) n Age: 6 months to 16 years (mean of 6 years) u Lethargy n Approximately half of cats are asymptomatic and diagnosed incidentally u Anorexia/weight loss n Approximately half of cats diagnosed with heart failure u vomiting secondary to HCM had a precipitating event

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HCM- genetic screening HCM-pathophysiology

n Inherited as an autosomal dominant trait with n Concentric hypertrophy results in incomplete penetrance in the Maine coon and Rag diastolic dysfunction which may be doll breeds exacerbated by myocardial fibrosis u Disease apparent in most cats by 6 months to n +/- systolic cavity obliteration and 2.5 years elevated LV filling pressure which leads n Inherited form of HCM has also been recognized to left atrial enlargement in a family of American short hair cats, but n +/- systolic anterior motion of the mitral pattern is less malignant than in the Maine coons valve (SAM) and dynamic obstruction n > 15 mutations have been recognized in humans

HCM- pathology HCM-diagnostics

n ECG

u Evidence of LVH (tall R waves) or LA enlargement (tall P waves) n LV hypertrophy n Radiographs n Often LA enlargement u Normal or left atrial enlargement or generalized cardiomegaly n Myocardial ischemia due to arteriosclerosis n Echocardiography n Histopathology u Increased LV wall thickness u Myocyte hypertrophy and disarray u LA enlargement u Diastolic dysfunction on transmitral Doppler and tissue Doppler

Restrictive cardiomyopathy (RCM) RCM-pathology

n This disease results in diastolic dysfunction secondary to endocardial, subendocardial or n LA enlargement myocardial fibrosis or infiltrative disease n Diffuse or focal endocardial plaque n Pathophysiologically similar to HCM since both n +/- fibrous adhesions between the papillary result in diastolic dysfunction muscles and myocardium, distorted chordae n Elevated ventricular filling pressure leads to atrial tendineae and mitral valve apparatus enlargement n Endocardial/myocardial scar formation n There may be a component of systolic dysfunction, particularly late in the disease

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RCM-diagnostics Unclassified cardiomyopathy n ECG- similar to HCM n Mixed aspects of various feline n Radiographs- similar to HCM cardiomyopathies making strict n Echocardiography categorization impossible

u Normal LV wall thickness u Normal wall thickness and systolic function

u LA enlargement u Restrictive filling pattern cannot be confirmed u +/- scarring or fibrosis of LV n Also called: intermediate or integrade u Restrictive transmitral filling pattern on Doppler cardiomyopathy u +/- Decreased systolic function (shortening fraction)

Dilated cardiomyopathy (DCM) DCM-pathology n Dilated heart with reduced systolic function n Taurine deficient DCM is rarely diagnosed n Primary dysfunction is systolic with poor currently, although occasionally cats still contractility, but diastolic dysfunction coexists respond to supplementation with taurine n Dilated heart with thin walls and secondary n Abyssinian, Burmese and Siamese are over- fibrosis represented

DCM-diagnostics Cardiomyopathy diagnostics

n n ECG- similar to HCM ECG- +/- tall R waves; +/- arrhythmias n Radiology- normal heart size to cardiomegaly, n Radiographs- similar to HCM congestive heart failure n Echocardiography n Echocardiography u Chamber dilation u Various findings depending on type of cardiomyopathy u Normal to decreased LV wall thickness u Gold standard for diagnosis of cardiomyopathy type

u Decreased systolic function (shortening n Ancillary tests to rule out extra-cardiac cause of fraction) hypertrophy u Mitral and/or tricuspid valvular regurgitation (central) u Thyroid panel, systemic blood pressure, growth hormone u nt-proBNP?

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Screening test- Electrocardiography Screening Test- Thoracic Radiographs n Poor accuracy for diagnosis of cardiomyopathy but test of choice for cats with arrhythmias n Left ventricular hypertrophy pattern: R wave amplitude >0.9mV in lead II n Left atrial enlargement pattern: Tall P waves n Left axis deviation or left anterior fascicular block may be present in cats with HCM (10-33%), is not specific and can be seen in normal cats as well

Vertebral Heart Size

! 5.3 4

Screening test- Echocardiography

n Echocardiography-

u LV wall thickness

u LV systolic function

u LA enlargement

u Diastolic function

t Transmitral Doppler, LVIVRT, tissue Doppler

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Echocardiography 2-D echocardiography

Doppler echocardiography

Mitral Annular tissue Doppler Transmitral Doppler

Possible cardiomyopathy outcomes

n Long, slowly progressive disease which never becomes symptomatic (or only very late in disease course) n Sudden death “Review of available evidence-based treatment data leaves no n Congestive heart failure uncertainties regarding drugs with established efficacy (in n Thromboembolic disease cats with occult disease). There presently are none.”

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Congestive Feline cardiomyopathy treatment heart n Occult affected (asymptomatic) cats failure u No medications have been shown to alter progression of disease n Secondary to severe diastolic dysfunction once u Reasons to consider treating the LA pressure exceeds 24 mmHg t Tachycardia/arrhythmia n Pulmonary edema and/or pleural effusion t Left atrial enlargement u Visceral pleural veins collect venous blood t Severe dynamic stenosis (SAM) from the pleural surface of the lungs and drain DCM is rare but if diagnosed it is the ONLY feline cardiomyopathy treated into the pulmonary veins in cats differently than the others: pimobendan, ACEI, TAURINE

Cardiomyopathy- treatment Cardiomyopathy- treatment

n Symptomatic cats with congestive heart failure n Symptomatic cats with congestive heart failure u Chronic stage u Acute stage t Furosemide is most important medication for cats t Furosemide with CHF t ACE inhibitor (enalapril or benazepril) t Oxygen therapy t Heart rate control if necessary (atenolol or t Nitroglycerin has never been shown effective in cats, but unlikely to cause adverse effects diltiazem) t +/- pimobendan t +/- Anticoagulant therapy t NEVER START BETA BLOCKERS IN t +/- Pimobendan (if systolic dysfunction) ANIMALS WITH UNCONTROLLED CHF

The 5 Ps Thromboembolic Disease

n Feline patients with cardiomoypathy are n Paralysis predisposed: n Pain u Virchow’s triad (prerequisites of thrombogenesis) n Pulselessness t Abnormal endothelial surface n Pallor t Abnormal blood flow (LA enlargement) n Poikilothermia t Increased coagulability

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Echocardiography- FATE Acute case management- FATE

n Manage pain n Control congestive heart failure and/or arrhythmias when present n General supportive care n Therapies to limit thrombus growth or future thrombus formation

Analgesia Nursing care

n Fentanyl n Address poor systemic perfusion (primary cause of

u 2-5 µg/kg/hr as a CRI until fentanyl patch takes effect hypothermia) n Butorphanol u Cautious fluid therapy with vigilant monitoring of RR,

u 0.1-0.2 mg/kg IV every 4 to 6 hours effort and auscultation for development of a gallop n Buprenorphine sound

u 0.005-0.015 mg/kg IV every 6 to 8 hours u Cautious warming (avoid peripheral vasodilation and worsening of core perfusion) n Methadone

u 0.1-1.0 mg/kg IM or SQ q 4 to 6 hours n Excellent nursing care and clinical laboratory monitoring u 0.05-0.2 mg/kg IV q 4 to 6 hours n Physical therapy

Feline cardiomyopathy therapeutic Anticoagulant therapy summary n Acute n What to treat and when? u No effect on established thrombi u Address congestive heart failure u Therapy is to prevent or reduce thrombus extension u Address myocardial failure t Heparin, clopidogrel t DCM or end stage HCM/RCM/UCM n Chronic u Address symptomatic arrhythmias u Clopidogrel u Address thromboembolic disease u Aspirin n Otherwise there is no evidence that treatments u Heparin alters outcome in cats with heart disease

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Feline cardiomyopathy therapeutic summary

n Treat congestive heart failure

u Furosemide +/- pleurocentesis

u Angiotensin converting enzyme inhibitor

u Pimobendan if echocardiographic evidence of systolic failure n Treat arrhythmias

u Frequent ventricular ectopy or supraventricular tachycardia

t Atenolol n Treat/prevent thromoboembolic disease

u Clopidogrel; aspirin

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