Management of heart failure Flashcards
What pt factors required considerations?
- primary causes of the heart dz
- non-specific tx of the primary dz
- tx of heart failure
- identify dysrhythmias and tx if indicated
- identify complicating & co-existing factors
- regular reassessment
- what does the O want?
Considerations with left sided heart failure
- more common -> think diseases
- pressure in the left side -> effective is more obvious
-> fluid in the lungs = life threatening
Considerations with right sided heart failure
- less common than left sided
- usually secondary to pericardial effusion or due to right sided valve dz
- often then leads to a degree of left sided dz
Typical presentation of heart dz
- heart failure
– cough/dyspnoea - exercise intolerance
- collapse
- heart dz found by chance
- non-specific malaise/weight loss
Non specific tx of primary dz - cardiomyopathy
- dilated cardiomyopathy = contractility failure
- drugs that improve contractility = positive inotropes
– digoxin (digitalis glycosides)
– pimobendan (vetmedin) **
– dobutamine
Pimobendan - what is it? use?
- gold standard
- inodilator = decreased systemic / pulmonary vascular resistance
- calcium-senitizing drug -> positive inotrope
- PDE III inhibitor -> vasodilation
- antithrombotic activity
- potential ‘feel good’ factor?
- slows dz progression and increases life expectancy
Digoxin - what is it? use?
- positive inotropic agent
- negative chronotropic agent
- increases vagal tone
- decreases sympathetic tone
- alters baroreceptor sensitivity
- predominantly renal excretion -> avoid drug or decrease dose in renal failure
- narrow therapeutic range
– GI signs with toxicity - aim for 0.5ng/ml-1ng/ml
- slows down the heart -> useful in animals with heart failure due to cardiomyopathy and tachycardia
Non specific tx of primary dz - HCM/RCM
Drugs that help the heart relax = positive lusitropes
- calcium channel blockers -> dilitazem, verapamil
- beta blocker -> propranolol, atenolol
In asymptomatic cats there is no evidence that any drug alters the natural history of HCM until they are in heart failure.
Diltiazem - what is it? use?
- licenced product
- have positive lusitropic properties
- may reduce LV hypertrophy
- ? benefit
- recent study: no effect on survival time in cats with severe HCM and HF
Goals for tx of CHF
- control salt & water retention
- reduce workload
– decrease afterload
– decrease physical activity & stress - improve pump function
– improve systolic function
– improve diastolic function
– reverse/modify myocardial remodelling
Standard CHF therapy
Triple/quad therapy
- diuretics
- pimobendan
- ACE inhibitors
- aldosterone antagonists
- ± anti-dysrhythmic meds
Staging heart dz
Stage A: pts at high risk of heart dz but have no identifiable structural disorder of the heart.
Stage B: pts with structural heart dz (e.g. murmur), but no CS
- Stage B1: asymptomatic pts with no radiographic or echocardiographic evidence of cardiac remodelling
- Stage B2: asymptomatic pts with radiographic or echocardiographic evidence of left-sided heart enlargement
Stage C: pts with past or current CS of heart failure associated with structural heart dz.
Stage D: pts with end-stage dz with CS of heart failure that are refractory to ‘standard therapy’.
Tx of CHF: Stage B1
Occult dz - no tx - but consider:
- weight control
- regular reassessment
- client education
Tx of CHF: Stage B2
Occult dz - no tx - but consider:
- pimobendan
- weight control
- regular reassessment
- client education
Tx of CHF: stage C
CS of CHF
- institute double/triple/quad therapy
Diuretics - use
- remove fluid: diuretic traditionally use
– act at kidney to increase urine output - control oedema formation
- oedema in CHF is usually due to increase in circulating blood volume
- blood volume can be increased by as much as 30% in severe CHF
Types of diuretics
Loop
- furosemide
- torasemid
Potassium sparing
- spironolactine
- amiloride
Thiazide
- hydrochlorothiazide
Furosemide - use
- 1s line diuretic
- very potent
- plasma 1/2 life is 15 mins -> peak effect orally is 1-2h -> duration of action is 4-5h
- more potent given parenterally
– iv causes vasodilation -> immediate effect - most important drug in dogs and cats
- loop diuretic
- SC/IM/IV/PO
- very potent, vasodilates IV
- acute severe dyspnoea
– 2mg/kg IV
– 1mg/kg hourly thereafter to control rr - 1mg/kg 14h weaning down to q8h
- frequency tailored to individual -> severity of volume overload and oedema
- can be high doses in some cases
- reduce dose asap
- monitor for azotaemia and hypokalaemia
- care in cats -> restrictive/hypertrophic dz: 1mg/kg BID
Spironolactine - use
- aldosterone antagonist -> potassium sparing effect
- beneficial effects in CHF -> improvements in cough, dyspnoea, syncope, mobility
- anti-fibrotic effect?
Problems with diuretics
volume depletion
-> stimulates RAAS
-> potential hypovolaemia
-> cause/exacerbate azotaemia
Vasodilators - ACE inhibitors - use
Dilate arteries, veins or both
Venous dilators
- decrease preload
- reduce fluid build up
- e.g. glycerol trinitrate
Arterial dilators
- reduce afterload
- increase output
- reduce valve leakage
- e.g. hyralazinel
They make it easier for the heart to eject blood and reduces pressure.
Treating pts with CS of CHF - ACE inhibitors
- aiming to remove fluid and vasodilate
- ACE inhibitor now used
– vasodilation (arteries & veins)
– decreased salt and water retention
Examples:
- Imidipril (Prelim)
- Enalapril (Enacard)
- Benazepril (Benfortin, Nelio, Priben, Fortekor, Kelapril)
- Ramipril (Vasotop)
Bear in mind azotaemia & hypotension
Cardalis - use
- combo of ace inhibitor (benazepril) and the aldosterone antagonist (spironolactone)
- once a day
- use quite a lot in cats
Role of pimobendan
- Stage B2 & C
- inodilator
- calcium sensitising drug -> positive inotrope
- PDE III inhibitors -> vasodilator
- anti-thrombotic activity
Stage D CHF
- advanced
- obvious CS with minimal exercise
- progressively worsens
- obvious CS at rest
- death
CHF therapy - emergency - presentation & goal
Present: coughing, dyspnoea, cyanotic, cough up fluid, raised chest
Goal:
- tx of life-threatening CHF is 1st priority
- take into consideration which other concurrent dz may be present
- current meds
Emergency CHF therapy
Furosemide
- 2mg/kg IV initially, then
- 1mg/kg hourly afterwards until resp rate and effort reduce (up to 4 doses in cats more as necessary in dogs)
Oxygen supplementation
Pimobendan? iv formulation
Cage rest
Avoid stress
Sedation as necessary (butorphanol 0.1-0.2mg/kg)
Monitor renal values / electrolytes
Anti-dysrhythmic meds if necessary
Emergency CHF therapy - once stable (rr normal)
- if bp allows gradually start low dose ACEi and wean up after 24-48h
- start spironolactone 2mg/kg SID
- pimobendan
- if hr not started to reduce after a few hours consider anti-dysrhythmic (typically AF)
- wean pt from iv furosemide to oral doses 3x daily
Other management ideas for CHF
Low salt diet?
- reduce salt intake -> activate RAAS system
- no real advantage putting on a cardiac diet
- avoid salt load (e.g. eating loads of crisps)
Exercise regime -> individual dog, consistency is key, don’t push till exhaustion
- want them to live longer and better
Aspirate fluid
- if there’s enough fluid for dyspnoea, there’s enough for you to remove safely
Clopidogrel - use
- inhibits platelet aggresation
- no EBM as yet
- appears relatively safe
– mild neutropaenia in some cases - very bitter taste
- 18.75mg/cat/day
