Management of Heart Failure Flashcards
With regards to patient management, there are a number of factors the require consideration - what are they?
- What does the owner want?
- A lot of owners might not be in the position to manage this as they require life long treatment
- Primary causes of the heart disease
- Non-specific treatment of the primary disease
- Treatment of heart failure
- We are good at treating congestive heart failure
- Identify dysrhythmias and treat if indicated
- Rhythm disturbances complicate things – rarely see an animal with just a disturbance that we need to treat, usually they are a complication of heart disease
- Identify complicating and co-existing factors
- Regular reassessment
- Most of primary diseases such as valve disease and cardiomyopathy, we cannot specifically treat them – might have some non-specific treatments such as something that might help with contractility if they are struggling with that etc.
Is left or right side heart failure more common?
Why?
•Left more common
–Diseases affect L more than R
–L is high pressure – effect more obvious
With heart failure, what develops with time?
•Congestion and oedema develop with time
–CONGESTION – elevated cardiac filling pressures
What are some typical presentations of heart disease?
- Heart failure
- Collapse or exercise intolerance
- Heart disease found by chance
- Non-specific malaise/weight-loss
- Cats often present acutely dyspnoeic
With heart disease, what are some reasons for presentaton to clinic when the murmur is first detected?
With patient management in a patient with heart failiure, what are some factors that require consideration?
- Primary causes of the heart disease
- Non-specific treatment of the primary disease
- Treatment of heart failure
- Identify dysrhythmias and treat if indicated
- Identify complicating and co-existing factors
- Regular reassessment
- What does the owner want?
Name 2 primary causes of heart disease
What is the cause?
Any treatment?
- Mitral valve disease
- Cardiomyopathy
- Cause unknown
- Cannot treat
What are some primary causes of a disease for heart failure which can be addressed?
- Some congenital lesions.
- Pericardial disease.
- Metabolic disease.
- Deficiency disease.
When can you use non-specific treatment of the primary disease that causes HF?
- If no primary cause for the disease is identified or it cannot be treated (e.g. MVD)
- Is non-specific treatment of the disease possible, for this primary disease?
- This requires a precise diagnosis of the type of primary disease
- Not always possible !
- Needs echocardiography diagnosis really!
What is the pathophysiology of DCM?
Dilated cardiomyopathy = pathophysiology behind this is contractility failure
What are positive inotropes?
Drugs that improve contractility
Name 3 positives inotropes
Drugs that improve contractility = positive inotropes
- Digoxin (digitalis glycosides) - oral
- Pimobendan (Vetmedin) – oral
- Dobutamine – can use IV infusion of this if dog is trying to die
What are some consequences of DCM?
E.g. what happens to contracility, SV etc
Contractility falls
Stroke volume falls
Cardiac output falls – detected as fall in BP
A positive inotrope tries to improve this contractility
Describe the effects of inotropes on heart function?
As pre-load goes up, ventricle filling goes up, as these myocytes are stretched, they contract more – so as pre-load goes up, contractility goes up
Positive inotropes moves this curve up and to the left
What kind of drug is digoxin?
Positive inotrope agent
Negative chronotropic agent
Increases vagal tone
Decreases sympathetic tone
Alters baroreceptor sensitivity
Dignoxin:
- what kind of inotrope?
- what kind of chronotropic agent?
- Positive inotropic agent
- Increase contractility
- Negative chronotropic agent
- Reduces HR
What does digoxin do to vagal tone?
Increases vagal tone
What does digoxin do to sympathetic tone?
Decreases sympathetic tone
What is digoxins therapeutic range like?
What are some signs of digoxin toxicity?
•Narrow therapeutic range - digoxin toxicity!
–Digoxin toxicity –off food, lethargy, depression, borbgrgymi , arrhythmias can all occur before the classical V and D. Recommended dose range is now 0.5-1.0 not the classical 1-2
–Can measure serum levels
When should you avoid using digoxin?
•Predominantly renal excretion
–Avoid drug or decrease dose in RF
What kind of drug is Pimobendan?
Inodilator
Calcium sensitive drug
Positive inotrope
How does Pimobendan work as a positive inotrope and vasodilator?
- Positive inotrope and vasodilator – does this by sensitising the molecules in cardiomyocytes to calcium, so for the same amount of calcium you get more contractility
- If you give dogs in heart failure this – they get a lot better! They certainly feel better
What effect does Pimobendan have on thrombotic activity?
Antithrombotic activity
What are positive lusitropes?
Drugs that help heart relax
Give some examples of positive lusitropes?
- Calcium channel blockers
- diltiazem, verapamil
- Beta blocker
- propranolol, atenolol
What class of drug would you use for cardiomyopathy in cats?
Cardiomyopathy:
- Hypertrophic/Restrictive (cats) – heart fills poorly
- Drugs that help heart relax = positive lusitropes
- Calcium channel blockers
- diltiazem, verapamil
- Beta blocker
- propranolol, atenolol
What is Diltiazem?
How effective is it?
- Licensed product
- Have positive lusitropic properties
- Slow response to APC
- May reduce LVH
- Diltiazem 5 mg TID
- ? Benefit
- Recent study no effect on survival time in cats with severe HCM and HF
In asymptomatic cats, what evidence is there to suggest that drusg alter the natural history of HCM?
In asymptomatic cats there is no evidence that any drug alters the natural history of HCM until they are in heart failure
In cats with heart disease, if there is severe LV outflow obstruction - what is frequently used?
•If severe LV Outflow tract obstruction then Atenolol is frequently used off license.
–Beta blocker to reduce contractility to try and reduce the amount of OF tract obstruction
What is Atenolol and what does it do?
When should it NOT be used?
- Heart rate control
- Anti-arrhythmic
- Reduce LVOFTO
- Decrease myocardial oxygen demand
- Selective Beta-1 agonist
- NOT to be used in heart failure
What are the goals of therapy for congestive heart failure?
- Control Salt & Water Retention
- Improve Pump Function
–(Improve systolic function)
–(Improve diastolic function)
–Reverse/modify myocardial remodeling
•Reduce Workload the sick heart is doing – do this by vasodilating the animal.
–Decrease afterload
–Decrease physical activity and stress
–Easier for ventricles to get blood out into systemic circulation – by vasodilation
With congestive heart failure, why do we need to control salt and water retention?
As our patient deteriorates, CO falls and body detects this as a fall in BP, activates SNS and RAAS – this results in arterial systemic and venous constriction and Na and water retention. These compensatory mechanisms want to get BP back up but the consequence is that, in time, the animal becomes fluid overloaded. If L side – pulmonary oedema
Why is it a problem and why do we need to be careful when controlling salt and water retention with the treatment of CHF?
A problem with loss of water and reduced workload – all of these mechanisms are activated to maintain BP, the body wants the BP, and if we are going to counteract these mechanisms and get rid of this fluid and vasodilate the constricted vessels – so the risk is that we do too much of this and drop the BP too much – so often treading a fine line.
With the treatment of CHF, what mechansism do we need to change to reduce the workload the sick heart is doing?
–Decrease afterload
–Decrease physical activity and stress
–Easier for ventricles to get blood out into systemic circulation – by vasodilation
What is triple therapy with regards to standard CHF therapy?
- Diuretics
- Pimobendan
- ACE Inhibitors
What is the quadruple therapy with regards to the standard treatment of CHF treatment?
- Diuretics
- Pimobendan
- ACE Inhibitors
- Aldosterone antagonists
What are some conbinations of drugs with regards to the standard treatment of Congestive HF therapy?
Combinations of drugs:
- Diuretics
- Pimobendan
- ACE Inhibitors
- Triple therapy: pharmaceutical companies make it easy by giving us combination therapies that mean we don’t have to give the animals loads of tablets
- Aldosterone antagonists
- 3 above plus this = Quadruple therapy: if they start developing signs of oedema
- Digoxin
- Inodilators
- Anti-dysrhythmic medication
What is stage A of the ACVIM consensus for assessing severity of heart disease/failure?
•Stage A - patients at high risk of heart disease but have no identifiable structural disorder of the heart
–So every dachshund and ever CKCS essentially has stage A heart failure…
What is stage B of the ACVIM consensus for assessing severity of heart disease/failure?
•Stage B - patients with structural heart disease (e.g. murmur), but no clinical signs
–Stage B1 - asymptomatic patients with no radiographic or echocardiographic evidence of cardiac remodelling
–Stage B2 asymptomatic patients with radiographic or echocardiographic evidence of left-sided heart enlargement.
–Dog middle age that comes in for vaccine and find murmur
What is stage C of the ACVIM consensus for assessing severity of heart disease/failure?
- Stage C - patients with past or current clinical signs of heart failure associated with structural heart disease.
- Patients with heart failure,
What is stage D of the ACVIM consensus for assessing severity of heart disease/failure?
- Stage D - patients with end-stage disease with clinical signs of heart failure that are refractory to ‘‘standard therapy’
- Refractory to standard therapy for heart failure
What treatment would you use for stage B1 of congestive heart failure??
“Occult” disease - no treatment - but consider
- Weight control
- Regular re-assessment
- Probably just by auscultation if its just valve disease
- Client education
- What can they look out for – does it exercise well, is there a cough, is it losing weight?
What treatment would you use for stage B2 of congestive heart failure??
- Stage B2: Asymptomatic (“occult” disease)
- WITH CARDIAC REMODELLING
- CARDIAC (ESP LA) ENLARGEMENT
- Clinically normal
- “Occult” disease - no treatment - but consider
- Pimobendan
- Weight control
- Regular re-assessment
- Client education
- Delays onset of stage C – so this is important
What do diuretics do?
Control oedema formation
Why do you get oedema function with CHF?
Oedema in CHF is usually due to increase in circulating blood volume
How much can blood volume be increased by in severe CHF?
Blood volume can be increased by as much as 30 % in severe CHF
What are types of diuretics used in CHF?
- Loop diuretics
- Furosemide
- First line treatment
- Torasemide
- Potassium Sparing
- Spironolactone
- aldosterone antagonist and the diuretic effect of this is probably pretty weak
- Amiloride
- Thiazide
- Hydrocholorothiazide
Why is it useful to know where different diuretics work in the nephron?
Work at different sights – useful just to remember this as if they become refractory to furosemide, can use a different diuretic that works at a different site or a combination – can improve diuretic effect
What is the first line diuretic?
Furosemide
Furosemide:
- How potent?
- Plasma half life?
- Peak oral effect?
- Duration of action?
- Very potent
- Plasma half time is 15 minutes
- Peak effect orally is 1-2 hours
- Duration of action is 4-5 hours
Which route makes furosemide more potent?
•More potent given parentally
–i/v causes vasodilation – immediate effect for acute heart failure situation
–Then send home on oral
•O often struggle managing PUPD
What is Torasemide and why is it better than furosemide?
- Once daily
- Launches a couple of years ago
- Big advantage – only needs to be given once a day, whereas due to the half life of furosemide, you have to give up to 3 times a day
- More potent diuretic
- Hasn’t taken off so well as: difficult to change habits as vets used to using furosemide and furosemide is so cheap but this isn’t as cheap as it’s a branded product
If you have acute severe dyspnoea with CHF, what drug should you use?
Furosemide
•Acute severe dyspnoea
–2mg/kg i/v
–1mg/kg hourly thereafter to control RR
–1mg/kg every four hours weaning down to 8 hourly (3x daily)
Why should we be careful with using Furosemide in cats?
•Care in cats
–Restrictive/hypertrophic diseases
–Preload dependent
–Use lower doses??
–1mg/kg BID?
•Heart disease in cats – physiological problem is that their V cannot fill so they are dependent on ore-load, they need a certain amount in order to keep CO up – if you diurese them, their CO falls and can compromise kidney perfusion in particular – so use lower doses in cats and then lower dose when home
What is Spironolactone?
How does it work
- Aldosterone antagonist
- Potassium sparing effect
- Anti-fibrotic effect?
- Will excrete more Na and water – potassium sparing, unlike furosemide
- The way this drug works may not actually be that a principle diuretic effect, understand now that there are lots of other effects on BV and heart muscle cells themselves
What is the 4th out of 4th choice drug for treatment of oedema in heart failure treatment?
What are some of its beneficial effects in CHF?
Spironolactone
- Beneficial effects in CHF
- Improvements in cough, dyspnoea, syncope, mobility
What are some problems with using diuretics?
Describe the vicious circle of heart failure
What do venous dilators do for the treatment of CHF?
Give an example of one
- Venous dilators
- decrease preload
- reduce fluid build up
e.g. glyceryl trinitrate
What do arterial dilators do for the treatment of CHF?
Give an example of one
- Arterial dilators
- reduce afterload
- increase output
- reduce valve leakage
e.g. hydralazine
What is now used instead of venous and arterial vasodialtors?
Ace inhibitors
How does ace inhibitors work?
- Theoretical benefits
- Veno and arterial vasodilation
- Decreased salt and water retention
- Local ACE and myocardial remodelling
- causes efferent arteriolar dilation causing a reduced glomerular filtration rate
- If you give dogs and cats in HF an ACE inhibitor – then they live longer
How does the RAAS work?
Where do Ace inhibitors work?
What are some contraindications for using ACE inhibitors?
Contra-indications:
- Fixed CO – AS, HOCM
- Renal dysfunction??
- K-sparing diuretics
- NSAIDs??
- Generally very safe though…
When using ACE inhibitors, what should you bear in mind?
What should we be measuring regularly?
•Azotaemia
–Monitor renal parameters
•Hypotension
–Monitor BP as we worry about it being too low
•Monitor renal parameters regularly
If we are using ACE inhibitors, and a patient has renal disease - which one may be best to use?
Benazepril may be more suitable for patients with renal disease, as less dependent on renal excretion – doesn’t make any difference – they are all equally safe
Name some ACE inhibitors?
•Imadipril
–Prilium
•Enalapril
–Enacard
•Benazepril
–Benfortin
–Nelio
–Prilben
–Fortekor
–Kelapril
•Ramipril
–Vasotop
What is Pimobendan?
- Inodilator
- Calcium-sensitizing drug
- Positive inotrope
- PDE III inhibitors
- Causes vasodilation
Why might Pimobendan be particularly useful in cats?
Anti-thrombotic activity – useful in cats. Not licensed in cats but a lot of people are using it for cats
What do you see with stage D heart failure severity?
- Obvious clinical signs with minimal exercise
- Progressively worsens
- Obvious clinical signs at rest
- Progressively worsens
- Death
Back to try to rescue these animals
What is the goal of emergency CHF therapy?
- Treatment of life-threatening CHF is 1st priority!
- Take into consideration which other concurrent diseases may be present
- Current medication
- Present acutely with life threatening CHF – stick probe on and see of there is pleural effusion, most cats present with this and if you drain the effusion, you save yourself a lot of time.
- Dogs present with pulmonary oedema usually
How can you manage ACUTE congestive heart failure?
- Furosemide
- Oxygen supplementation
- Pimobendan if systolic dysfunction (all CDVD and DCM cases)
- Cage rest and monitor resp rate
- Avoid stress
- Sedation as necessary (Butorphanol 0.1 - 0.2mg/kg)
- Some my benefit from this as they get themselves in a real state
- Glyceryl trinitrate ointment
- Monitor renal values / electrolytes
- Antidysrhythmic medication if necessary
If blood pressure allows, what should you do with ACE inhibitors, spironolactone, digoxin and furosemide with regards to emergency treatment of CHF?
- If blood pressure allows gradually start low dose ACEI and wean up after 24-48 hrs
- Start spironolactone 2mg/kg SID
- IF AF rate not started to reduce after a few hours then start digoxin
- Wean patient from i/v furosemide to oral doses twice – three times daily
Other than drugs, what are some other options for the treatment of congestive heart failure?
- Low salt diet
- No evidence that it makes much difference really
- We want them to keep eating though!! They go off their food which usually pushes owners to PTS
- Exercise regime
- They can benefit from this, but exercised within its capacity – BE CONSISTENT
- Aspirate fluid
- Last resort in dogs
- May need to aspirate ascitic fluid
- Pleural effusion removal if life saving
With the treatment of CHF, what should you do with regards to exercise?
–Within the dog’s capacity
– CONSISTENCY DAY TO DAY
– Do not allow to become exhausted
– Why are we treating dogs
- make them live longer
- make them feel better
What is clopidogrel used as a treatment for?
What does it do?
Feline thromboembolic disease
Inhibits platelet aggregation
Aspirin can also be used for the treatment of feline thromboembolic disease as an inhibitor of platelet aggregation. What should we take care of?
- Gastric ulceration
- GIT upsets
- Renal compromise
What are some specific anti-dysrhythmic therapy drugs?
beta blocker, calcium channel blocker, digoxin
