Management of Congestive Heart Failure Flashcards
what is forward failure
decreased cardiac output
what does forward failure cause (3)
- exercise intolerance
- lethargy
- syncope
what is backward failure
congestive heart failure
what does left sided backward failure cause (2)
- dyspnea
- tachypnea
what does right sided backward failure cause (4)
- hepatomegaly
- ascites
- dyspnea
- tachypnea
what are the general drugs used to treat CHF (6)
- preload reduction & control of effusions (diuretics, +/- venodilators)
- afterload reduction (vasodilators)
- positive inotropic support
- improved diastolic functino
- management of significant arrhythmias
- control of cardiac remodelling (ACEIs, spironolactone, ARBs, +)
what are the diuretics used
- loop diuretics: furosemide, torasemide
- sprionolactone
- amiloride/hydrochlorothiazide (off license)
when are diuretics contraindicated
CHF secondary to cardiac tamponade
what is diuretic resistance
excess diuresis, severe CHF, NSAIDs all cause a decrease in renal blood flow which leads to the activation of renin
renin –> angio II –> aldosterone –> Na+ and water reabsorption –> decreased urine Na+
where do thiazides and loop diuretics act
in the loop of henle
where does amiloride act
in the distal convoluted tubule, connecting tubules, and collecting ducts in the nephron
where does spironolactone act
in the collecting duct
which is more potent diuretic furosemide or torasemide
torasemide and it seems less prone to resistance
what is used to reduce the afterload reduction (3)
- vasodilators
- ACE inhibitors
- pimobendan
what vasodilators are used to reduce the afterload (3)
- ACE inhibitors
- amlodipine
- hydralazine
what ACE inhibitors are used to reduce afterload (3)
- benazepril
- ramipril
- enalapril
how do ACE inhibitors work (5)
counteract maladaptive RAAS activation
- decrease angiotensin II
- decrease vasoconstriction
- decrease ADH secretion
- decrease aldosterone
- decrease sympathetic stimulation
how does pimobendan work
positive inotrope (inodilator) and vasodilator
what medications are used for positive inotrope support (3)
- pimobendan
- digoxin
- dobutamine infusion
how does digoxin work
poor positive inotrope but good negative chronotrope
what could systolic failure be due to
primarily due to DCM or secondary to chronic volume or pressure overload or chronic tachycardia
what is used to improve diastolic function (2)
- positive lusitrope (improve relaxation): diltiazem, pimobendan
- negative chronotropes (decrease heart rate): beta-blockers, diltiazem
what is abnormal diastolic function seen with
myocardial hypertrophy (HCM), fibrosis
why should anti-arrhythmic drugs be used carefully in CHF
because all anti-arrhythmic drugs are negative inotropes (except digoxin) and can make CHF worse initially, so monitor CHF and rhythm carefully
what arrythmias should be treated in CHF
- supraventricular tachyarrhythmias
- ventricular tachyarrhythmias
- bradyarrhythmias
what is remodelling due to
response of the cardiac chambers to chronic volume or pressure overload
through neuroendocrine/RAAS system activation
it may become maladaptive
which drugs have been shown to slow down remodelling (3)
- ACE inhibitors
- spironolactone
- pimobendan
what cases of CHF can be cured (5)
- patent ductus arteriosus
- pulmonic stenosis
- idiopathic pericardial effusions
- tachycardia induced cardiomyopathy
- bradycardia related CHF
what are the CHF classification systems
- new york heart association (1964)
- international small animal cardiac health council scheme (1994)
- american college of cardiology/american heart association (2001)
how is CHF classified according to the american heart association
A. at risk of heart disease
B. structural heart disease but asymptomatic
C. structural heart disease with current or prior CHF
D. refractory heart failure
how can degenerative mitral valve disease (DVMD) be classified according to AHA
A. at risk: ex. being a CKCS
B. asymptomatic; no remodelling: murmur, no cardiomegaly
C. asymptomatic, but remodelling present: murmur, cardiomegaly
D. refractory CHF: refractory dyspnea, ascites
for DVMD explain what you would do for a class A patient (at risk, CKCS) (2)
- physical exam: heart rate, rhythm (respiratory sinus arrhythmia), respiratory rate and character (annually)
- educate owner: pre-disposed breed may develop heart disease and what signs to watch for (ex. decreasing exercise intolerance, persistent cough) though both have many potential causes
what would you do for a class B1 patient for DMVD (5)
monitor for cardiomegaly
- physical exam: heart rate, rhythm (loss of respiratory sinus arrhythmia), respiratory rate and character (every 6months)
- +/- thoracic radiography: increased vertebral heart score
- +/- echocardiography: increase LA:Ao and LVIDDN (left ventricular internal diastole dimension)
- serial biomarker (NT-proBNP)
- educate owner: pre-disposed breed may develop heart disease and what signs to watch for (ex. decreasing exercise intolerance, persistent cough) though both have many potential causes & signs of congestive heart failure (sleeping respiratory rate)
what should you do for a B2 patient with DMVD
treat with pimobendan
reduced heart size short and long term
why is it important to look out for cardiomegaly in dogs with DMVD
because dogs that are put on pimobendan take longer to reach CHF compared to dogs who aren’t on it
pimobendan gave dogs a longer symptom free period and it also reduced heart size short and long term
how are dogs classified between B1 and B2
3.5% of dogs have a murmur, breed, age, etc consistent with MMVD but the minority of practices have echo equipment/expertise
in a lot of cases of MMVD the disease may never progress to CHF
so its hard to classify whether or not a dog is B1 or B2
how do dogs classed as B2 progress to C for DMVD
the progression is generally slow but usually increases in pace later
how do you monitor for CHF and the progression to class C in dogs that are classed B2
- resting/sleeping respiratory rate: very sensitive to lung fluid load
home monitoring of SRR by owners is very important in detecting onset of CHF and response to therapy
smart phone apps are availble to help owners count, record and transmit SRR data to the clinician
once a patient reaches class C in DMVD what should be done
furosemide/torasemide & pimobendan
ACE inhibitor & spironolactone
+/- anti-arrhythmics if required (atrial fibrillation)
how is furosemide used
to control CHF then reduce dose to lowest dose necessary to control clinical signs
enough but not too much –> give owner some control over decision making (urination/noctuira a potential problem)
how does pimobendan help with CHF (5)
- positive inotrope: PDE inhibitor, Ca2+
- vasodilator: inhibits PDE III & PDE V
- improves myocardial relaxation
- decreases cytokines TNF-alpha, IL-6, IL-1b (inflammatory sydrome that contributes to weight loss and ataxia)
- reduces remodelling
what is the efficacy of pimobendan in DMVD
pimobendan compared to benazepril (ACE inhibitor) showed that it took dogs almost twice as long to reach primary end point (composite cardiac death, euthanasia) than benazepril
evidence shows that pimobendan is not a rescue drug and it should be used as soon as dogs with DMVD decompensate (if not already on it)
what are the benefits of spironolactone in dogs with DMVD
potential benefits but need more research
aldosterone blocker –> aldosterone has been shown as a mediator of inflammation & fibrosis in pathologyical remodelling in the heart in CHF
what medications are used to treat supraventricular tachycardia/atrial fibrillation
- digoxin (off license)
- atenolol (off license)
- diltiazem
but often digoxin combined with diltiazem and they work better together than on their own
what medications are used to treat ventricular arrhythmias
- lidocain IV infusion at first
- mexiletine (off license) common in dogs
- atenolol (off license) common in cats
- sotalol (off license) common in cats
- amiodarone (off license) common in dogs
how is diet used to manage CHF (5)
- avoid excessive salt intake
- monitor serum potassium +/- supplement esp if inappentent or high dose diuresis
- feed diet rich in omega 3?
- make sure adequate calorie intake to try to avoid cardiac cachexia
- small & frequent, appetizing, calorie dense
how are dogs with DVMD exercised (4)
- maintain regular exercise regime: important for quality of life for dog and owner
- no excessive exertion
- avoid exercising when very hot; clipping long coats may help
- use a harness or halit if coughing a problem
how is CHF monitored in DMVD (2)
regular monitoring of patient is essential –> will imrpove survival
- regular monitoring of renal functioning and electrolytes is essential, also body weight & condition
- digoxin levels should be checked after 5 days and if patient is unwell, esp if inappetent or vomiting
how are patient in class D managed (5)
- consider additional diuretics (amiloride + hydrochlorthiazide) and torasemide if not already in use
- recalculate & +/- increase doses; ensure owner engagement/compliance is good
- reconsider antiarrhythmic therapy
- specific treatment for pulmonary hypertension if present (sildenafil)
- consider antitussives (cough)
how is CHF in dilated cardiomyopathy managed
management no different to mitral valve disease
arrhythmias more common esp atrial fibrillation and ventricular arrhythmias
tendency for right sided CHF to occur eariler
how is acute decompensation managed in CHF dogs (8)
- IV furosemide boluses/CRI
- glyceryl trinitrate “percutol” (venodilator off license)
- oxygen
- IV pimobendan OR
- IV dobutamine (off license)
- additional afterload reduction (if ruptured chorda: amlodipine, hydralazine)
- thoracocentesis if needed; rarely abdominocentesis
- antiarrhythmic therapy if needed IV or oral
how are cats with chronic CHF (4)
- diuretics: furosemide or torasemide (off license) +/- spironolactone
- ACE inhibitors
- +/- pimobendan (off license)
- all cats with enlarged atria should be on aspirin (off license) or preferably clopidogrel
what is the biggest problem in treated cats with CHF
getting formaultions that they will take
how are supraventricular arrhythmias in cats treated (3)
- diltiazem
- atenolol (off license)
- digoxin (off license very low dose)
care as both diltiazem and atenolol are ngative inotropes and may make CHF worse
how are ventricular arrhythmias treated in cats (2)
- atenolol
- sotalol
care as both are negative inotropes and may make CHF worse
lidocaine rarely used and dose much lower compared to dogs
cats often tolerate arrhythmias better
what is shown here
left anterior fascicular block and a ventricular ectopic
what is shown here
atrial fibrillation with left anterior fascicular block
how are cats with CHF in acute decompensation treated (7)
- gentle handling
- thoracocentesis if needed
- oxygen
- cage rest
- IV furosemide CRI/bolus
- glyceryl trinitrate (off license)
- pimobendan IV (off license) or dobutamine IV (off license)
