Management of Heart Failure

Question 1

Outline the compensatory mechanisms in response to heart failure and how they themselves can lead to CHF

Answer 1

RAAS systems leads to salt/water retention

Fluid builds up in the vessels -especially the veins

Venous pressure rises

High venous pressure leads to fluid being pushed out of veins

Leading to congestion/oedema

But output & CO are restored

Eventually the patient will decompensate and undergo congestive heart failure and disease progression

Backward failure - congestion

Forward failure - poor perfusion

Question 2

List the systems involved in the compensatory response

Answer 2

SNS
RAAS
ADH (antidiuretic hormone - water retention)
Natriuretic peptides
Atrial stretch

Question 3

Describe left sided heart faulire

Answer 3

Congestion of the pulmonary venous circulation
-Drain the lungs

Most common
Due to high pressure the effect is more obvious
Leads to fluid in lungs which is life threatening

Question 4

Describe right sided heart failure

Answer 4

Congestion of the systemic venous circulation

-Drain the body

Question 5

Explain stage A at assessing severity of HF

Answer 5

Patients at high risk of heart disease but have no identifiable structural disorder of the heart

-breed associated disease

Question 6

Explain stage B at assessing severity of HF

Answer 6

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.
-Cardiac enlargement (especially LA)

Question 7

Explain stage C at assessing severity of HF

Answer 7

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

Mild: Evidence of limited exercise intolerance

Moderate: Signs evident with mild exercise

Question 8

Explain stage D at assessing severity of HF

Answer 8

Patients with end-stage disease with clinical signs of heart failure that are refractory to ‘‘standard therapy’’

Advanced
Obvious clinical signs with minimal exercise
Progressively worsens
Obvious clinical signs at rest
Sudden collapse/death

Question 9

Outline the treatment process of heart faulire

Answer 9

Identifying primary cause of the disease

Non specific treatment of the primary disease

Treatment of congestive heart failure

Identify dysrhythmias and treat if indicated

Identify complicating and coexisting factors

Regular reassessment

What does the owner want?

Question 10

Explain why there is no singular treatment for heart failure

Answer 10

• Cause of heart disease varies.
  
  • Presenting clinical signs varies.
  • Disease progression varies.
  • Response to treatment varies.

Question 11

Describe the process in identifying the primary cause of the disease

Answer 11

Valve degeneration
Mitral
Aortic

Cardiomyopathy

Cause unknown

Cannot treat

Question 12

Describe what is meant by non specific treatment of the primary disease

Answer 12

Requirement of precise diagnosis of the type of primary disease

In cases of primary disease that cannot be identified or if it is untreatable (valve degeneration) it must be considered if treatment would be possible

Ultrasound (echocardiography) usually required

Question 13

Explain how dilated cardiomyopathy is treated with non specific targets

Answer 13

Dilated = contractility failure
Drugs that improve contractility = positive inotropes
- Digoxin (digitalis glycosides)
- Pimobendane (“Vetmedin”)
- Dobutamine

Question 14

Explain how hypertrophic/restrictive cardiomyopathy is treated with non specific targets

Answer 14

Heart fills poorly
Drugs that help heart relax = positive lusitropes
- Calcium channel blockers
diltiazem, verapamil
- Beta blocker
propranolol, atenolol

Question 15

Describe how Stage B1 of congestive heart failure is treated

Answer 15

No treatment but to consider:
Weight control
Regular reassessment
Client education

Question 16

Describe how Stage B2 of congestive heart failure is treated

Answer 16

No treatment but to consider:
Pimobendane
Weight control
Regular reassessment
Client education

Question 17

Describe how Stage C of congestive heart failure is treated

Answer 17

Clinical signs of CHF
Due to oedema formation
Cough/breathing problems in L heart failure
Fluid accumulation in body cavities in R heart failure

Treatment:
Remove fluid - diuretic traditionally used

Vasodilatation 

Act at kidney to increase urine output
	Loop diuretics – furosemide, torasemide
	Aldosterone antagonists - spironolactone
	ACE inhibitor

Question 18

Explain how vasodilators are used in treatment for stage C congestive heart failure

Answer 18

Dilate arteries, veins or both break the vicious cycle of heart failure

Act by:
	Reduce arterial blood pressure - afterload
	Reduce venous pressure - preload

Reduction of load and therefore cardiac work

Clinical uses: 
	Treatment of cardiac failure
	Antihypertensive agents

Question 19

How do Venodilators work?

Answer 19

During HF salt & water retained leading to high venous pressure, increasing preload. Eventually leads to oedema formation

Venodilators reduce preload by increasing venous capacity, dropping the pressure within veins. Reducing oedema formation

Question 20

How do arterial dilators work?

Answer 20

During HF vasoconstriction arteries reduces cardiac output and increase the afterload, leading to increased AV regurgitation.

Arterial dilators reduce afterload, by increasing cardiac output. Leads to a reduction work for the heart and this valve leakage decreases

Question 21

Explain how the use of ACE inhibitor cause decongestion

Answer 21

Reduce level of angiotensin II
Venous dilators
Arterial dilators

Reduce levels of aldosterone
Reduce fluid accumulation

Question 22

List examples of ace inhibitor

Answer 22

• Imadipril
  Prilium
  - Enalapril
  Enacard
  - Benazepril
  Benfortin
  Nelio
  Prilben
  Fortekor
  Kelapril
  - Ramipril
  Vasotop

Question 23

Outline other treatments used in congestive heart disease

Answer 23

Low salt diet – efficacy??

Exercise regime
exercise within capacity

Aspirate fluid – pleural/abdominal

Acute onset of left heart failure
Severe respiritory distress
-Cage reset
-Oxygen therapy

Question 24

Outline the process of identifying dysrhythmias and treatment

Answer 24

Dysrhythmias are common in patients with heart disease

These will require characterisation with an ECG

Specific antidysrhythmic therapy may be required
e.g. beta blocker, calcium channel blocker, digoxin

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Question 25

Discuss what is meant by regular assessment in the therapeutic treatment process

Answer 25

• Assess patient for side effects, toxicity etc
• Drug doses may need to be adjusted
  There is rarely a standard dose
• Regular blood chemistries are advisable
• Repeat investigations if indicated
• Weigh

Aim is resolution of clinical signs
Rarely a cure

Question 26

Understand mechanisms by which drugs may fail to be effective

Answer 26

Therapy failure
Dose too low – dose by surface area not weight?

Administration failure?

Absorption if given by mouth?

Tachyphylaxis

Question 27

Outline how there may be adverse effects to therapy

Answer 27

Dose too high - lean weight/fluid presence

Idiosyncratic reaction

Complicating factors - renal dysfunction

Co-existing disease - liver dysfunction

Effect of combinations - polypharmacy?