2.2.4: Heart failure management Flashcards
True/false: whatever the cause, cardiac output falls and is detected via a drop in blood pressure.
True
* Degenerative valvular disease -> regurgitation means less forward flow into the aorta
* Dilated cardiomyopathy -> forward flow falls due to poor contractility
* Restrictive / hypertrophic cardiomyopathy -> forward flow falls because heart cannot fill
* Congenital disease - variable
Factors to consider in management of the patient with heart disease
- Primary cause of heart disease and if this can be addressed
- Treatment of heart failure
- Identification of dysrhythmias and treatment if indicated
- Identifying any complicating and co-existing factors
- Regular assessment
- What does the owner want?
Typical presentation of heart disease
- Heart failure: cough/ dyspnoea
- Exercise intolerance
- Collapse
- Non-specific malaise / weight loss
- Occasionally heart disease is found by chance
Stage A heart disease
(ACVIM statement)
patients at high risk of heart disease but that have no identifiable structural disorder of the heart e.g. every CKCS
Stage B heart disease
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 cardiac enlargement.
Stage C heart disease
patients with past or current clinical signs of heart failure associated with structural disease.
Stage D heart disease
patients with end-stage disease with clinical signs of heart failure that are refractory to “standard therapy”
What treatment would you prescribe for a patient in Stage B1 heart disease?
Patient does not require specific treatment at this time, but consider:
* Weight control
* Regular reassessment
* Client education
What treatment would you prescribe for a patient in Stage B2 heart disease?
- There is occult disease with cardiac remodelling especially left atrial enlargement
- Prescribe pimobendan PO
What treatment would you prescribe for a patient in Stage C heart disease?
- This patient has clinical signs of congestive heart failure
- Time to institute double / triple / quad therapy
- i.e. Pimobendan + diuretics/ ACE inhibitors/ aldosterone antagonists
What is right-sided heart failure typically secondary to?
- Usually secondary to pericardial effusion or due to right-sided valvular disease
- Often then leads to a degree of left-sided disease
What are the goals of heart disease treatment?
- Control salt and water retention
- Reduce workload for heart by decreasing afterload and decreasing physical activity and stress
Improve the pump function (improve systolic function, diastolic function, and reverse/ modify myocardial remodelling
Indications for vasodilator use
- When there are clinical signs of CHF
- -> aiming to remove the fluid by vasodilation and by decreasing salt and water retention
What should you monitor when using vasodilators like ACE inhibitors?
- Must monitor renal parameters!
- We need to make sure there is not azotaemia/ hypotension
What is the mode of action of ACE inhibitors? How does this help the patient in heart failure?
ACE inhibitors = vasodilators
They dilate veins, arteries, or both.
Venous dilators
* Decrease preload
* Reduce fluid buildup
Arterial dilators
* Reduce afterload
* Increase output
* Reduce valve leakage
Examples of ACE inhibitors
- Imadipril
- Enalapril
- Benazepril
- Ramipril
What drugs could we use to treat DCM?
DCM = contractility failure. Need drugs that improve contractility (positive ionotropes).
e.g. Digoxin, pimobendan
Which patients should you avoid using digoxin in?
Patients with renal disease - digoxin is excreted renally
Effects of pimobendan
- Positive ionotrope: improves contractility; is a calcium-sensitising drug
- Inodilator: leads to decreased systemic/ pulmonary vascular resistance
- Causes vasodilation
- Has anti-thrombotic activity
- Used in Stage B2 and Stage C patients
What drugs could we use to treat RCM/HCM?
RCM/HCM = the heart fills poorly. Need to help the heart relax -> Positive lusitropes
e.g. calcium channel blockers: diltiazem, verapamil
e.g. beta-blockers: propanolol, atenolol
In asymptomatic cats, there is no evidence that any drug alters the course of HCM until they are in heart failure.
How should you treat the animal who presents as an emergency with congestive heart failure?
- Oxygen
- Cage rest
- Avoid stress
- Butorphanol (IM) to sedate as necessary
- Furosemide IV until resp rate and resp effort reduce
- Consider pimobendan IV
- Monitor for dysrhythmias and consider anti-dysrhythmic medication if needed
- Monitor renal values/ electrolytes
A patient presented in acute CHF. You have now stabilised them. What is your plan going forward?
- If BP allows, gradually start low dose ACE inhibitor and increase over 24-48hrs
- Start spironolactone PO SID
- Start pimobendan PO
- Wean patient from IV furosemide to PO 3x daily
- If HR has not started to reduce after a few hours, consider anti-dysrhythmic medication (might have atrial fibrillation)
How would a patient in acute CHF present?
- Dyspnoeic
- Cyanotic
- Coughing/ coughing up fluid
- Keeping a raised chest
How do diuretics work? How does this benefit the patient in heart failure?
- Diuretics remove fluid - they act at the kidney to increase urine output
- They control oedema formation in the patient in CHF
What type of diuretics are there?
- Loop diuretics e.g. furosemide
- Potassium sparing diuretics e.g. spironolactone
- Thiazide
How does furosemide work?
Furosemide = loop diuretic
* Very potent
* Plasma half life = 15 mins
* Peak effect orally = 1-2 hrs
* Duration of action = 4-5 hrs
* Can be given SC, IM, IV, orally. Most potent given IV -> causes vasodilation with immediate effect
* Good for acute severe dyspnoea
* Tailor to severity of volume overload and oedema
* If high dose needed, reduce ASAP
* Take care in cats with restrictive/ hypertrophic disease (1mg/kg BID)
What should you monitor for when using loop diuretics like furosemide?
Monitor for azotaemia and hypokalaemia
How does spironolactone work?
Spironolactone
* Aldosterone antagonist (hence potassium sparing effect)
* Beneficial in CHF: improvements in cough, syncope, mobility
Management of heart failure - non-medical options
- Low salt diet: reducing salt intake could activate RAAS/ minimal benefit. Avoid salt load.
- Exercise regime: consistency is key, do not push them to exhaustion.
- Aspirate fluid
Complications of heart failure treatment
Renal insufficiency (pre-renal)
* Likely due to overdoing it on the therapy side i.e. leading to decreased blood volume and poor renal perfusion
Electrolyte imbalance (esp K+)
* Furosemide leads to K+ loss
* ACE inhibitors lead to K+ retention
* Spironolactone leads to K+ retention
* Generally hyperkalaemia is rare; hypokalaemia is common!
Uses of clinical pathology in heart disease
- Often not useful in identifying primary disease; could potentially tell us about bacterial endocarditis
- Useful for routine monitoring: clinical biochemistry and electrolytes
- Useful for assessing the deteriorating patient: may be renal / K+
- Useful for assessing therapy failure
- Markers elevated in cardiac failure: natriuretic peptides e.g. BNP, ANP
- Markers elevated in myocardial disease e.g. troponins
What can you do if treatment is failing?
- Change treatment: increase dose/ frequency of furosemide/ ACE inhibitor; increase dose of pimobendan
- Consider adding other drugs: antidysrhythmic/ negative chronotropes (E.g. for atrial fibrillation), add sildenafil if pulmonary hypertension, add additional diuretic if needed, add codiene/ butorphanol
- If the animal decompensates, go back to emergency treatment
What should you make the owner aware of in terms of long-term management of heart disease?
- Disease is lifelong and requires lifelong management
- Emphasise need for regular daily routine
- Administer prescribed medication consistently
- Consistent exercise schedule needed
- Must maintain appetite
- Warn about possible side effects/ toxic effects of medications
- Prognosis poorer in cardiomyopathy
Co-existing diseases that may contribute to failure and how this occurs
Hypothyroidism
* Normally T3 and T4 increase bloodflow and cardiac output - n their absence we will see reduced cardiac output.
* Also see low voltage complexes in hypothyroid animals.
Cushing’s
* Many clinical signs common to heart failure
* e.g. protein/muscle catabolism
* Commonly same signalment: middle aged to older small breed dogs
