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