Dog Cat exam 3

heart failure

progressive fatal syndrome where heart

• reduces CO

• increases venous pressure

• deteriorates heart function

right sided backward (congestive) heart failure signs:

• jugular distention

• pleural effusion

• hepatomegaly

• ascites

left sided backward (congestive) heart failure signs:

• pulmonary edema

• pulmonary venous distention

forward heart failure signs:

• poor CO

  • lethargy

  • weakness

  • hypotension

  • exercise intolerance

  • cold extremities

  • syncope

  • azotemia

neurohromonal response to heart failure

in the short term these mechanisms increase CO but over time they exacerbate heart failure and reduce CO

sympathetic beta 1 stimulation leads to…

• increased HR

• increased contractility

• improved relaxation

sympathetic alpha stimulation leads to…

• vasoconstriction (increased afterload)

RAAS system

preload

blood volume ventricles are filled with before they contract (measured as end diastolic volume or pressure)

preload is mainly influenced by blood ________

volume

stroke volume

volume of blood ejected with each heartbeat

how does preload affect SV?

afterload

resistance heart encounters to ejecting blood (increases with increased ventricle volume and arterial resistance)

how does afterload affect SV?

contractility

strength of heart contraction (estimated by echo)

SV increases/decreases with contractility

increases

distensibilty

ease of ventricular filling during diastole (ability to stretch)

With decreased distensibility, there is increased/decreased ventricular pressure for the same ventricular volume

increased

heart failure classification:

• A: risk of heart disease

• B heart disease with no signs

  • B1: no chamber enlargement

  • B2: enlargement left atrium and ventricle

• C: past or current signs of heart failure

• D: end stage disease

Reduced CO effects:

• sympathetic beta stimulation

• vasoconstriction

• RAAS activation (Na and water retention)

Congestive heart failure resp rate is >_____/min

40

right side CHF signs:

• ascites

• jugular vein pulsation

murmur grade 1

very quiet that is hard to locate

murmur grade 2

quiet murmur

murmur grade 3

murmur as loud as heart sounds

murmur grade 4

murmur louder than heart sounds

murmur grade 5

very loud murmur with precordial thrill

murmur grade 6

very loud with precordial thrill detected with stethoscope lifeted from chest wall

vertebra heart sum in dogs should be <_____ vertebrae

10.5 (measure width and height and add them together)

vertebral left atrial size should be < ______ vertebrae

2.4

pulmonary veins should be the same size as the ___ rib

9th

RAAS system activation lab abnormalities:

• hypokalemia

• pre-renal azotemia

NT-proBNP

marker for congestive heart failure (myocardial stretch)

cardiac troponin I

marker of cardiomyocyte damage (keep in mind a lot of things can damage the heart)

ECG leads

50 mm/s speed

• 5 cm = 1 sec

• complexes x 20 = HR/min

25 mm/s

• 5 cm = 2 sec

• complexes x 10 = HR/min

tachycardia

>160 BPM

ventricular arrhythmia

what kinds of ventricular arrhythmia are treated?

• ventricular couplets, triplets, runs

• vtach

ventricular arrhythmia treatment:

• lidocaine IV

• sotalol PO

• atenolol PO (not in heart failure)

lidocaine, solatol, and atenolol effects:

supraventricular arrhythmia

what kinds of supraventricular arrhythmias are treated?

• supraventricular tachycardia

• atrial fibrillation

supraventricular arrhythmias treatment:

• diltiazem PO or IV (Ca blocker)

• sotalol PO

• atenolol PO (not for heart disease)

conduction blocks

increase length of time between atrial and ventricular depolarization

mitral valve disease treatment:

• furosemide for pulmonary edema

• pimobendan to increase contractility

• ACE-inhibitor to inhibit RAAS

• spirinolactone for anti aldosterone

what should not be done for mitral valve disease?

• fluids

• drugs that vasoconstrict (dexmedetomidine)

degenerative valvular disease pathogenesis:

• mitral regurgitation→increased left atrial volume, pressure→pulmonary edema→ remodeling, myocardial failure

what heart failure categories receive treatment?

B2, C, and D

treatment for valvular disease with B2 heart failure:

pimobendan

treatment for valvular disease with C or D heart failure:

• pimobendan

• furosemide

• ACE inhibitor

• spirinolactone

what is the next step for a dog with a 3/6 heart murmur?

thoracic radiographs for vertebral heart sum

what is the next step for a dog with a VHS <10.5?

no treatment, repeat rads in 3-6 months

what is the next step for a dog with a VHS >10.5?

echocardiography

what is the next step for a dog with a B2 heart failure, VHS >11.5, or VLAS >3?

pimobendan

what factors contribute to HCM development in cats?

hypertrophic cardiomyopathy types:

• localized

• generalized

• papillary muscle

hypertrophic cardiomyopathy pathogenesis:

• left ventricular hypertrophy

• impaired left ventricular relaxation

• left atrium enlargement

• increased pressure in left atrium leading to pulmonary edema

• endothelial disruption and slow flow

• thrombus formation

• section of thrombus dislodges, aortic thromboembolism

• obstruction of blood flow

HCM signs:

• asymptomatic

• heart murmur, gallop

• arrhythmia

• CHF

• sudden paresis/paralysis

• tachycardia or bradycardia

• tachypnea/dyspnea

• pulmonary edema, pleural effusion

• weak pulse

where do aortic thromboembolisms occur?

• at start of aorta close to heart

• saddle thrombus where caudal aorta bifurcates

HCM radiograph findings:

• VHS >9.3

• pulmonary edema

• pleural effusion

HCM echo findings:

• hypertrophic left ventricle walls

NT-proBNP

heart product that can predict likelihood of heart disease

what is the treatment for left ventricle outflow tract obstruction with no heart failure?

atenolol

atenolol effects:

• reduces HR and prolongs filling

• can cause arrhythmias

Rapamycin

drug that regulates mTOR which is involved in cellular growth and stress responses and can potentially be used to slow the progression of HCM

thrombus treatment:

• clopidogrel

• rivaroxaban

• aspirin

• low molecular weight heparin (deltaparin, enoxaparin)

CHF treatment:

• drain any effusion

• furosemide

• O2

• reduce stress

• pimobendan

• ACE inhibitor

• spirinolactone

cardiomyopathy phenotypes

pulmonary edema pathogenesis:

atrial fibrillation

• absence of P waves

• irregular rhythm

• tachycardia

• ± f waves

• narrow QRS complexes

what is the most common clinically relevant arrhythmia diagnosed in dogs?

A-fib (can be secondary to DCM, MVD)

A-fib consequences:

• no atrial contribution to filling

• tachycardia

• reduced CO

• increased filling pressures

• increased myocardial O2 demand

• worsening of CHF

dilated cardiomyopathy phenotype:

• dilation of left ± right ventricle

• decreased contractility

• second most common canine acquired cardiac disease

• more common in large dogs

• may or may not have heart murmur

DVD/MVD cardiomyopathy phenotype:

• small dogs

• most common cardiac disease

• murmur before heart failure

• can cause left atrium or left ventricle dilation secondary to volume overload

causes of primary DCM:

• genetic

• idiopathic

causes of secondary DCM:

• nutritional

• tachycardia-induced

• toxicity (doxorubicin)

• infectious (trypanosoma cruzi/chagas disease)

nutritional DCM is due to…

taurine deficiency

progression of canine DCM

what drugs reduce preload?

• furosemide

• ACEi

what drugs reduce afterload?

• ACEi

• pimobendan

what drugs increase contractility?

• pimobendan

what drugs increase distensibility?

• ACEi

• spirinolactone

when should tachycardia be treated in DCM?

pathologic tachyarrhythmia

how to treat stage B DCM:

• pimobendan

• benazepril

arrhythmogenic right ventricular cardiomyopathy (ARVC)

progressive fibrofatty replacement of right, and to some degree left ventricular myocardium (seen in boxers) that manifests as right ventricle arrhythmias

arrhythmogenic right ventricular cardiomyopathy (ARVC) signs:

• asymptomatic

• exercise intolerance or syncope associated with ventricular arrhythmia

• systolic dysfunction and CHF

arrhythmogenic right ventricular cardiomyopathy (ARVC) diagnosis:

• ECG

• holter

• ± echo

• myocardial biopsy (best but rarely done)

arrhythmogenic right ventricular cardiomyopathy (ARVC) treatment:

only if clinical signs are present or if arrhythmia is severe

• sotalol

• mexiletine

• combination

ascites pathogenesis:

causes of right sided CHF:

1. pericardial effusion/cardiac tamponade

2. pulmonic stenosis

3. pulmonary hypertension

pericardial effusion/cardiac tamponade pathogenesis:

excessive fluid in pericardial sac→reduced filling of cardiac chambers→reduced cardiac output

causes of pericardial effusion/cardiac tamponade in dogs:

• cardiac neoplasia

• idiopathic

• less common: right CHF, LA tear secondary to valve disease, trauma, migrating foreign body, coagulopathy

causes of pericardial effusion/cardiac tamponade in cats:

• CHF

• iatrogenic fluid overload

• FIP

• tumors

pericardial effusion/cardiac tamponade treatment:

• pericardiocentesis

right CHF with no pericardial effusion treatment:

• ascites: furosemide, pimobendan, abdominocentesis

• pulmonary hypertension: sidenafil

continuous left sided heart base murmurs are caused by…

PDA

systolic left sided heart base murmurs are caused by…

• aortic stenosis

• pulmonic stenosis