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Insights Into The Feline Heart Understanding, Diagnosing, and Treating
Feline Cardiomyopathy WhitChurch,DVM,DiplomateACVIM(Cardiology)DesertVeterinaryMedicalSpecialistsGilbert,Scottsdale,andGlendale,AZ
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Why are Cat Heart Sounds So Difficult to Characterize?
A. Gallop heart sounds can be hard to detect. B. Murmurs in cats all sound the same. C. Cats are small; the valve areas are close
together. D. The position of the heart in the thorax changes
w/age. E. Most feline heart murmurs are dynamic (labile). F. Knowledge deficits about murmur location,
prevalence. G. All of the Above.
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Cardiac Auscultation in Cats
Theneglectedarea:ventralthoraxdirectlyoverthe
sternum
Catheartmurmurs:• Virtuallyalwayssystolic• Locationdescribedasleftorrightparasternal
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Why are Cat Heart Sounds So Difficult to Characterize?
Youngcat Oldcat
The position of the heart in the thorax changes w/age.
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Why are Cat Heart Sounds So Difficult to Characterize?
Cats are small; the valve areas are close together.
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Common Acquired Heart Diseases of Cats
! Cardiomyopathy Ø Hypertrophic (HCM)
Ø Restrictive (RCM) or Unclassified (UCM)
Ø Less Common Ø Dilated (DCM) Ø Arrythmogenic Right Ventricular (ARVC)
! Systemic Hypertension (SH) ! Hyperthyroidism (HT4)
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Common Acquired Heart Diseases of Cats
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Restrictive Cardiomyopathy
Hypertrophic Cardiomyopathy
MostCommonPrimaryMyocardialDiseases
HCM mRCM/eRCM
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Left Ventricular Hypertrophy in Cats
Hypertrophic Cardiomyopathy
Hyperthyroidism
Systemic Hypertension
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Pathology of HCM Myocardial Fiber Disarray
LV Hypertrophy
Myocardial Fibrosis
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TheThreeMostCommonHeartMurmursofAdultCats
Dynamic RVOT Obstruction Dynamic LVOT Obstruction
DSAS, SAM, HOCM Mitral Regurgitation
DSAS, SAM, HOCM
Normal Ejection
RVOT Obstruction
LVOT Obstruction
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Dynamic LVOT Obstruction
! Systolic anterior motion (SAM) of the mitral valve
Ao Ao
LA LA
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Dynamic LVOT Obstruction
early systole
mid systole
latesystole
DynamicLVOTobstruction:• Causedbysystolicanteriormotion(SAM)ofthemitralvalve• Createsasourceofpressureoverloadtotheleftventricle• PressureoverloadàconcentrichypertrophyinanalreadyhypertrophiedHCMheart!
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Systolic Anterior Motion of the Mitral Valve
Results in additional Hypertrophy!!!
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Dynamic RVOT Obstruction
Normal
DRVOTObstruction
UnlikeLVobstruction,RVobstructionisrelativelybenignanddoesnotappeartocauseoverloadtotheheart.
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ABCDClassificationofFelineHeartFailure
!At Risk for Heart Failure !Stage A Subclinical, apparently healthy but high risk for
developing heart disease !Stage B1 Subclinical, Normal to mild LA enlargement,
Ventricular remodeling !Stage B2 Subclinical, Moderate to severe LA enlargement,
Ventricular remodeling
!Heart Failure ! Stage C Past or current signs/symptoms of CHF or ATE ! Stage D End stage HF, signs refractory to Rx
ACVIM Cardiology CVD Consensus Statement Guidelines. ACVIM Forum 2019
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Physical Examination
Thoracic Radiography
Echocardiography
Electrocardiography
Laboratory Testing
History Patient Profiles
Diagnosis?
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After Hearing a gallop or murmur, what is the next step in the cardiac evaluation?
A. ECG B. NT ProBNP C. Blood Pressure D. Serum Thyroid Levels E. Thoracic Radiographs F. Echocardiogram
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Diagnosis of Systemic Hypertension
SAP>190mmHgon3ormoreoccasionsSAP>170mmHg+Ocularlesions
LVhypertrophyCNSsigns
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HCM: Differential Diagnoses
! Older Cats with LVH ¦ Hyperthyroidism ¦ Systemic hypertension
! Younger Cats with LVH/DSAS ¦ Mitral valve dysplasia
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Routine Clinical Evaluation
! ECG, thoracic radiographs, NT ProBNP ! Echocardiography ! Systemic blood pressure (Doppler) ! T4, CBC, chemistry, UA
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SNAP® Feline proBNP
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! Semi-quantitative SNAP test ¦ Similar to SNAP cPL or
SNAP fPL ¦ Reference spot and a
Sample spot ¦ Read time is 10 minutes
! Tool to help assess heart health pet-side ¦ Abnormal results indicate
increased stretch and mechanical stress on the myocardium
SNAP Feline proBNP
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Interpreting SNAP Feline proBNP Results
From the SNAP Feline proBNP Diagnostic Update
Field Trial Data
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Potential Uses for NT-proBNP in Cats
! Detection of heart disease in an asymptomatic cat
! Differentiating causes of dyspnea: Ø Cardiac vs. Respiratory Ø Help interpret radiographs
! The big question is, “Where do we place the cutoff value to avoid false positives and false negatives.”
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! Feline NT-proBNP pmol/L
50 100 200 1000+
NoSymptoms
CatDyspneic
HeartDiseaseUnlikelyRecheckin6-12months
HeartDiseaseProbable-EchoIndicated
HeartdiseaseProbableEchoIndicatedChestRadiographs+/-
HeartDiseasePossible-EchoIndicated
ChestRadiographs-HeartFailureUnlikely
ChestRadiographs-HeartFailureUnlikely-Echo+/-
ChestRadiographs-HeartFailurePossible-EchoIndicated
ChestRadiographs-HeartFailureProbable-EchoIndicated
Interpreting NT-proBNP in Cats
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HCM - Electrocardiography
Leftaxisshiftpattern:LeftAnteriorFascicularBlock(PartialLeftBundleBranchBlock)
I
II
III
aVL
aVF
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Thoracic Radiography in Cats
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Thoracic Radiography in Cats
VHS=8.5
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Vertebral Heart Scale
NormalValues
Dogs:8.5–10.5vertebraCats:6.9–8.1vertebra
Validoverawiderangeofbreeds,chestconformations,andagesinbothdogsandcats
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HCM - Echocardiography
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Echocardiography
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! Concentric LV hypertrophy Ø Asymmetric septal hypertrophy Ø Regional hypertrophy
! Dilated LA as disease worsens ! Small LV chamber ! Intracardiac thrombi (usually in the left atrium)
HCM - Echocardiography
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Case 1: Henry
! 9-yr old, 10lb, MN Persian presents to your hospital with a complaint of acute onset, short, rapid breathing.
! Current medications: monthly heartworm preventative
! No murmur ! Mild crackle in the right cranial lung field ! Normal femoral pulses
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Henry’s Radiographs
Evaluate:1. Heartsize2. Heartshape3. Lungfields4. Pulmonaryvessels
VHS=8.9
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Evaluate:1. Heartsize2. Heartshape3. Lungfields4. Pulmonaryvessels
Henry’s Radiographs
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! Radiographic diagnosis: Ø Moderate enlargement of the left atrium suspected.
Ø Distended and indistinct pulmonary veins/vasculature.
Ø There is an alveolar pattern in the right cranial lung field.
Ø Rule outs include pneumonia or congestive heart failure.
Henry: Radiographs
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How do I decide? What else can I do?
Additional Diagnostics?
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! 260 pmol/L (Positive on the SNAP)
50 100 200 1000+
NoSymptoms
CatDyspneic
HeartDiseaseUnlikelyRecheckin6-12months
HeartDiseaseProbable-EchoIndicated
HeartdiseaseProbableEchoIndicatedChestRadiographs+/-
HeartDiseasePossible-EchoIndicated
ChestRadiographs-HeartFailureUnlikely
ChestRadiographs-HeartFailureUnlikely-Echo+/-
ChestRadiographs-HeartFailurePossible-EchoIndicated
ChestRadiographs-HeartFailureProbable-EchoIndicated
Perform an NT-proBNP?
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HCM - Echocardiography
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HCM - Echocardiography
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HCM - Echocardiography
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HCM - Echocardiography
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Henry’s Diagnosis!
RecommendedMedications:
HypertrophicCardiomyopathyCongestiveHeartFailureNoOutflowObstruction
Lasix(~2mg/kg/day)
ACEInhibitor(Benazepril0.5mg/kgBID)
SecondaryTreatments:ConsiderAspirinorPlavixtopreventthrombisformation,Forrefractorypulmonaryedemaorpleuraleffusion:Spironolactone2mg/kgq24hrsorpossiblyVetmedin(Pimobendan0.25mg/kgBID)
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Who Needs Atenolol Therapy?
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Cat A: Alice CHF
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Cat B: Buttons SAM
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I
II
III
aVF
CatC:CharlotteLAFB
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Who Needs Atenolol Therapy?
A. Alice
B. Buttons
C. Charlotte
:AtenololcanreducetheSAMinducedLVOTObstructionandreducetheleftventricularhypertrophysecondarytotheobstruction.
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Questions?