Treatment of heart failure Flashcards
What is pathophysiology of CV disease?
heart failure or cardiac insufficiency prsent when heart cannot meet demands of the body at normal or elevated filling pressures
many heart diseases can remain compensated for some time
awareness of compensatory mechanisms vital to avoid iatrogenic problems with therapy
What are factors that influence cardiac output?
- preload–increased preload improve stroke volume up to a pount then get congestion
- afterload–reduce, improve CO
- contractility–increase, improve CO
- heart rate: incrased HR improves CO up to a point
What is an issue with ramapril?
drops blood pressure a lot and makes dog feel weak
What might be an issue with increasing cardiac contractility?
can increased work of heart (increased oxygen consumption) with possibly impaired perfusion
Why do we reduce preload?
to decrease congestion
What is the benefit of reducing afterload?
reduces stretch, work of the heart–reduction of heart remodelling, arrythmias
What is the RAAS system
renin-angiotensin-aldosterone system. renin released by kidney in response to hypoperfusion, decreased slat delivery and adrenergic stimulaition. Renin converts angiotensinogen to angiotensin I which is converted to AT II by angiotensin converting enzyme
What do ace inhibitors do?
they inhibit angiotensin converting enzyme. in people they cause pril cough in animals don’w
What are two drugs that interrupt RAAS?
ace inhibitor
angiotensin II receptor blocker
What are the effects of angiotensin II?
- vasoconstrictor–increased afterload
- increased aldosterone–increased salt and water retension
- increased thirst
- increased GFR
- myocardial hypertrophy
deleterious in long term
What is the classification scheme of heart disease?
Stage A-risk for HR dz stage B-structural HR dz no signs (B1 normal imaging, B2 abnormal) Stage C: past or current HR failure Stage D current failure refractory to standard therapy
Dobermans and cavalier king charles spaniels are considered in what stage when born?
stage A
What is an example of stage B1
heart murmur, no heart enlargement
What is an example of stage B2
enlarged heart but no cough etc
What are the general recommendations for stage A
- routine monitoring–holter monitor every 6mo, echo
2. no treatment recommended
What are the general recommendations for stage B
- imaging–differentiate B1 or B2
- BP measurement recommended
- echo when rads and physical not adequate to assess patient
- basic lab work
- large breed dogs–echo + radiograph
- treatment? no consensus–differnet for endocardiosis vs DCM
- consider ACE inhibitors–reduce preload, afterload, intefere with production of hormones–scar tissue formation in heart
What are the benefits of ACE inhibitors?
- mild preload reduction
- afterlaod reduction
- interfere with RAAS activation
If you give an ACE inhibitor to stage B DCM animals (asymptomatic) before heart failure, what happens?
improves quality of life and prolonges life span?
If you give an ACE inhibitor to an animal in heart failure what happens?
improves quality of life and lifespan
If you give an ACE inhibitor to an animal that is asymptomatic that has endocardiosis (heart murmur) some B1, some B2 is there a benefit?
no–not to onset of failure or lifespan
What can cockers get?
DCM or endocardiosis. if give DCM thiamine they survive much longer
What are the recommendations for stage C?
- reduce preload to reduce congestion
What animals benefit from pimobenan in stage B?
e.g. dobermans with DCM
no data on endocardiosis
What should you do with dogsin stage B?
if DCM dog, give ACE inhibitor, pimobendan. if endocardiosis don’t do anything
What is furosemide/features
REDUCES PRELOAD powerful loop diuretic: potassium wasting--predisposition to arrhythmia, digoxin toxicity--rarely issue in dog, may be in cat activates RAAS!!! (low volume) can cause low output failure (powerful) only indicated for pulmonary edema
If you have an animal with evidence of forward failure, what should you be cautious using?
drugs like furosemide that can cause low output failure
WHy should you titrate furosemide down to lowest dose possible/
to prevent forward output failure
What are the features of spironolactone?
aldosterone antagonist
potassium sparing
“add-on” diuretic, oft with chlorthiazide
not a diuretic in healthy dogs (not diuretic if have normal aldosterone maybe)
“in” drug now
was commonly used w/ liver ascites?
What is the benefit of spironolactone in people at least?
blocks adosterone, so stops cardiac remodelling
even on ACE inhibitors due to ACE escape and local tissue production of hormones
Should you use spironolactone?
not enough evidence to suggest is useful
What are the features of nitroglycerine?
- venodilator
- pools blood in abdomen away form lungs
- antithrombotic
- good for emergency
What are cons of nitrogylcerine?
have to apply to skin
tolerance develops!
How does nitrogycerine work?
enhances production of NO
When is nitroglycerine used?
- for emergency work
good in cats, failry mild preload reducer so don’t get a lot of negative side effects and antithrombotic (cats more likely to develop thrombus)
2.end stage when already on ALL the drugs.
HOw do you get around tolerance of nitrogylcerine?
administer first in the morning, then at night to try to get longer period between treatments
or two day on, one day off but in people cause head aches
What is a way to get rid of preload that is dietary adjustment?
low salt diet
What is the problem with low salt diets?
- not recommended in early stages because drugs likely to be working, in late failure may be helpful but doesn’t work vey well. 2. If used in combo with aggressive therapy can lead to RENAL problems–ARF–perfusion issue
can be more hassle than worth
What are three drugs that reduce afterload?
ACEi
Hydralazine
Nitroprusside
(amlodipine)
What is the mechanism of hydralazine? what are some of the issues of hydralazine?
it is an arteiral dilator
does not prolong lifespan
can cause significant hypotension
What are the features of nitroprusside?
need t be able to continuously monitor blood pressure
can cause symptomatic hypotension.renal failure
What are the features of amlodipine?
afterload reduction calcium channel blocker mainly used for hypertension in cats can improve exercise tolerance need to make pressures are good first monitor renal failure
What is the usefulness of inotropic support?
can be useful in emergency
Most drugs that provide inotropic supprt are whawt?
adrenergic agents
What are two adrenergic agents that provide ionotropic support?
dobutamine
dopamine
What are the features of dobutamine?
expensive and CRI only. inotorpic support
What are the features of dopamine
inotropic support
cheaper, can cause arrhythmias and at higher doses vasoconstriction!
What are the features of digoxin?
inotropic support
will increase cardiac contractility
most positive effects probably from upregulating vagal tone (baroreceptor ton)
slows down AV node–good for supraventricular tachycardias
low therapeutic index!
What breed is particularly sensitive to digoxin?
dobermans
Toxicity of digoxin is exacerbated by what?
hypokalemia and renal insufficiency
What is the drug that does it all?
pimobendan
What are the features of pimobendan?
- inodilator
- positive inotrope
- calcium sensitizer
- phosphodiesterase 3 and 5 inhibitor
- antioxidant
- antiplatelet effects
What would phosphodiesters 3 and 5 inhibitors be used for?
pulmonary hypertension because would cause vasodilation whereas ACE inhibitors only cause vasodilation downstream from left side of heart
what is a problem with older positive inotropes?
get more contractility of the heart but not improving health and leading to rapid death
Does pimobendan increase the risk of sudden death due to heart failure?
no. but does not decrease it either
How much does pimobendan improve doberman survival?
from 2-3 months to 4-5 months?
What is viagra used for?
pulmonary hypertension
If you have to choose between ACEi and pimobendan, which should you choose?
pimobendan (if don’t have to pick then use both)
If you put a dog on pimobendan? is the owner likely to see improvement in how they are doing?
yes. probably greater than ACEi
What were the effects of pimobendan use in endocardiosis?
improved systolic function
but increased jet lesions, mitral valve lesions
probably not good with early endocardiosis
Is pimobendan used in cats?
can be used in cats but not sure if it makes a difference
Do we use anything with occult hypertrohpic cardiomyopathy in cats?
no
What are 4 supplements that can be used in heart disease?
- taurine
- carnitine
- coenzyme Q10
- Essential fatty acids
What is the use of taurine?
dogs and cats with DCM
maybe in dogs that have DCM that don’t think should have DCM. Won’t work in great dane, irish wolfhound, doberman because that is genetic DCM
Could use in portuguese water dogs, newfies, dalmatians, cockers
What is the use of carnitine?
limited benefit
much more expensive than taurine
can consider in boxers, bulldogs, dalmatians
What is the use of omega 3 fatty acids?
1 modulate inflam (reduce cytokines
- antiarrhythmic in humans
- PUFA blunts TNF cachexia–limits cachexia in dogs with heart disease
When might you use omega 3 fatty acids?
reduce VPCs
use in atrial fibrillation
