2.2.4: Heart failure management

Question 1

True/false: whatever the cause, cardiac output falls and is detected via a drop in blood pressure.

Answer 1

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

Question 2

Factors to consider in management of the patient with heart disease

Answer 2

• 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?

Question 3

Typical presentation of heart disease

Answer 3

• Heart failure: cough/ dyspnoea
• Exercise intolerance
• Collapse
• Non-specific malaise / weight loss
• Occasionally heart disease is found by chance

Question 4

Stage A heart disease

(ACVIM statement)

Answer 4

patients at high risk of heart disease but that have no identifiable structural disorder of the heart e.g. every CKCS

Question 5

Stage B heart disease

Answer 5

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.

Question 6

Stage C heart disease

Answer 6

patients with past or current clinical signs of heart failure associated with structural disease.

Question 7

Stage D heart disease

Answer 7

patients with end-stage disease with clinical signs of heart failure that are refractory to “standard therapy”

Question 8

What treatment would you prescribe for a patient in Stage B1 heart disease?

Answer 8

Patient does not require specific treatment at this time, but consider:
* Weight control
* Regular reassessment
* Client education

Question 9

What treatment would you prescribe for a patient in Stage B2 heart disease?

Answer 9

• There is occult disease with cardiac remodelling especially left atrial enlargement
• Prescribe pimobendan PO

Question 10

What treatment would you prescribe for a patient in Stage C heart disease?

Answer 10

• This patient has clinical signs of congestive heart failure
• Time to institute double / triple / quad therapy
• i.e. Pimobendan + diuretics/ ACE inhibitors/ aldosterone antagonists

Question 11

What is right-sided heart failure typically secondary to?

Answer 11

• Usually secondary to pericardial effusion or due to right-sided valvular disease
• Often then leads to a degree of left-sided disease

Question 12

What are the goals of heart disease treatment?

Answer 12

• 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

Question 13

Indications for vasodilator use

Answer 13

• When there are clinical signs of CHF
• -> aiming to remove the fluid by vasodilation and by decreasing salt and water retention

Question 14

What should you monitor when using vasodilators like ACE inhibitors?

Answer 14

• Must monitor renal parameters!
• We need to make sure there is not azotaemia/ hypotension

Question 15

What is the mode of action of ACE inhibitors? How does this help the patient in heart failure?

Answer 15

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

Question 16

Examples of ACE inhibitors

Answer 16

• Imadipril
• Enalapril
• Benazepril
• Ramipril

Question 17

What drugs could we use to treat DCM?

Answer 17

DCM = contractility failure. Need drugs that improve contractility (positive ionotropes).
e.g. Digoxin, pimobendan

Question 18

Which patients should you avoid using digoxin in?

Answer 18

Patients with renal disease - digoxin is excreted renally

Question 19

Effects of pimobendan

Answer 19

• 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

Question 20

What drugs could we use to treat RCM/HCM?

Answer 20

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.

Question 21

How should you treat the animal who presents as an emergency with congestive heart failure?

Answer 21

• 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

Question 22

A patient presented in acute CHF. You have now stabilised them. What is your plan going forward?

Answer 22

• 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)

Question 23

How would a patient in acute CHF present?

Answer 23

• Dyspnoeic
• Cyanotic
• Coughing/ coughing up fluid
• Keeping a raised chest

Question 24

How do diuretics work? How does this benefit the patient in heart failure?

Answer 24

• Diuretics remove fluid - they act at the kidney to increase urine output
• They control oedema formation in the patient in CHF

Question 25

What type of diuretics are there?

Answer 25

* Loop diuretics e.g. furosemide * Potassium sparing diuretics e.g. spironolactone * Thiazide

Question 26

How does furosemide work?

Answer 26

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)

Question 27

What should you monitor for when using loop diuretics like furosemide?

Answer 27

Monitor for azotaemia and hypokalaemia

Question 28

How does spironolactone work?

Answer 28

Spironolactone * Aldosterone antagonist (hence potassium sparing effect) * Beneficial in CHF: improvements in cough, syncope, mobility

Question 29

Management of heart failure - non-medical options

Answer 29

* 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

Question 30

Complications of heart failure treatment

Answer 30

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!

Question 31

Uses of clinical pathology in heart disease

Answer 31

* 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

Question 32

What can you do if treatment is failing?

Answer 32

* 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

Question 33

What should you make the owner aware of in terms of long-term management of heart disease?

Answer 33

* 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

Question 34

Co-existing diseases that may contribute to failure and how this occurs

Answer 34

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