Tx of CHF Flashcards

1
Q

What is the process of CHF?

A
  • defined as abnormal fluid accumulation as a result of heart disease
  • Increased atrial pressures lead to increased capillary hydrostatic pressure
  • Fluid accumulates in the interstitial spaces (pulmonary oedema) or body cavities (pleural effusion or ascites)
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2
Q

What are the stages of heart failure?

A
  • Stage A: Animals at risk of heart disease but showing no evidence of disease at present time (e.g. breeds with a predisposition to heart disease such as CKCS, Doberman, Maine Coon, Ragdoll)
  • Stage B1: Asymptomatic animals with structural heart disease but no radiographic or echocardiographic evidence of cardiac remodelling
  • Stage B2: Asymptomatic animals with structural heart disease and radiographic or echocardiographic evidence of cardiac remodelling
  • Stage C: Patients with structural heart disease and current or previous signs of CHF
  • C1: Animals on treatment with previous signs of CHF
  • C2: Animals with mild to moderate signs of CHF
  • C3: Animals with severe life-threatening CHF signs
  • Stage D: Patients with chronic CHF who are refractory to standard treatment
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3
Q

How should Stage A pets be treated?

A

No meds indicated/ nutrition
Screening of breeding stock is usually indicated via auscultation, echocardiography, Holter monitoring or genetic testing

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4
Q

How should Stage B1 pets be treated?

A
  • No drug therapy or dietary changes are indicated in the early stage of the disease
  • Haemodynamic function may be relatively unaffected and there may be little or no neurohormonal activation
  • Re-evaluation with radiography or echocardiography within 12 months is indicated to assess for progression
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5
Q

What did the EPIC study demonstrate?

A

• Demonstrated that dogs with preclinical myxomatous
mitral valve disease (MMVD) and cardiomegaly are more likely to go into heart failure within 1-2 years
• Asymptomatic dogs with MMVD and cardiomegaly who received pimobendan (0.4-0/6 mg/kg/day in divided doses) experienced a 15 month delay in onset of clinical signs of CHF, cardiac-related death or euthanasia compared to dogs receiving placebo

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6
Q

What are the recommendations for occult DCM (stage B2)

A
  • The PROTECT study showed that the administration of pimobendan to Dobermans with preclinical DCM delays the onset of CHF or sudden death and improves survival
  • A small study in Dobermans with occult DCM in 2009 suggested that ACE inhibitor treatment may be beneficial
  • Some clinicians use both pimobendan and ACE inhibitors in dogs of high-risk breeds with occult DCM
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7
Q

What are the recommendations for cats with stage B2 HCM?

A
  • Asymptomatic HCM cats may live many years and most (80%) die from non-cardiac causes
  • Some cardiologists initiate treatment in high risk categories of cats with Stage B HCM:
  • Cats with ventricular tachyarrhythmias
  • Cats with severe left ventricular outflow tract obstruction due to SAM
  • Cats with severe left ventricular hypertrophy
  • Cats with left atrial enlargement (a risk factor of cardiac death and aortic thromboembolism)
  • However, data supporting the clinical or functional benefit of such early therapy are currently lacking

In humans, the clinical signs associated with HCM and SAM primarily occur during exercise/ exertion and beta-blockers are used for symptomatic relief
• Cats are said to sleep 85% of their life
• An indoor cat may never exert itself
• An indoor/outdoor cat may exert itself occasionally
• Sleep is better at keeping the sympathetic nervous system low than any drug

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8
Q

What are the general treatment recommendations for acute life threatening CHF?

A

• Stabilize patient prior to performing detailed investigations. Gentle handling of cats
• Removal of abnormal fluid accumulation (pulmonary oedema, pleural effusion) is usually a priority
• Improve oxygenation by increasing the inspired oxygen concentration and removing large pleural effusions (by thoracocentesis) or resolving pulmonary oedema (with loop diuretics, with or without venodilation)
• Frusemide dose in acute CHF: 2-4 mg/kg (IV, IM) every 1-2 hours until respiratory rate decreases
• Sedation if anxiety is exacerbating dyspnoea (e.g. butorphanol 0.1-0.2 mg/kg)
Drain pericardial effusions leading to cardiac tamponade

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9
Q

What are the general nutritional recommendations for chronic CHF?

A

Dietary advice include monitor weight, sustain caloric intake,
ensure adequate protein-intake (avoid low-protein diets), modestly reduce salt intake, omega-3 fatty acid supplementation

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10
Q

In general, what drugs are used to treat CHF in cats?

A

The most common drugs used for treatment of CHF in cats include:
• Frusemide
• ACE inhibitors
Other drugs used in cats with CHF include:
• Antiplatelet drugs
• Spironolactone
• Pimobendan in DCM and other cardiomyopathies with systolic dysfunction

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11
Q

How can you treat refractory CHF in cats?

A
  • Spironolactone can be beneficial in the treatment of CHF secondary to cardiomyopathy when added to standard treatment with frusemide and ACE inhibitor
  • Thiazide diuretics can be used in some refractory cases
  • Pimobendan can be prescribed to cats with LV systolic dysfunction
  • Periodic thoracocentesis is required in some cases
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12
Q

Outline the use of low salt diets in heart disease?

A
  • Do not use before the onset of CHF as low sodium intake can activate the renin angiotensin-aldosterone system
  • Low-salt diets can be unpalatable and difficult to use in advanced CHF when appetite is poor
  • Avoid salt loading but modest salt restriction is better than aggressive salt restriction
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13
Q

Outline taurine deficiency in cats

A
  • Taurine is an essential amino-acid for cats
  • Taurine deficiency was a common cause of DCM in cats until the late 1980s
  • Since then most commercial diets have been supplemented with taurine which has dramatically reduced the incidence of feline DCM
  • Cats on vegetarian and vegan diets are most likely to be deficient of taurine
  • In suspected cases blood taurine levels should be analysed and treatment with taurine (250-500 mg PO per cat BID) should begin concurrent with medical therapy
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14
Q

Outline taurine deficiency in dogs

A

• Taurine deficiency and taurine-responsive cardiomyopathy has been found in American
Cocker Spaniels and a number of other breeds
• Dogs with DCM and taurine deficiency that do respond to taurine supplementation generally do not have as dramatic a response as do taurine-deficient cats with DCM

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15
Q

Which drugs should and should not be given with food?

A
  • The bioavailavility of pimobendan is reduced when administered with or shortly after food
  • Administration of digoxin with food may result in up to a 50 per cent reduction in serum concentration of the drug
  • Spironolactone, conversely, should be given with food
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16
Q

What are general exercise recommendations for heart disease patients?

A
  • Restrict exercise until signs of CHF resolve
  • Regular mild to moderate exercise is generally recommended for dogs with stable heart disease (improves skeletal muscle tone and general quality of life)
  • Sudden sprinting or strenuous exercise should be avoided in dogs with exertional syncope or at risk of sudden death due to arrhythmias
  • As always, cats will do their own thing (especially sleeping)
17
Q

Which diseases can be treated with sx/ a catheter?

A
  • Surgical ligation of PDA
  • Occlusion device for PDA closure
  • Balloon catheter dilation of severe pulmonic stenosis
  • Pacemaker implantation for symptomatic bradyarrythmias
  • Pericardiocentesis/subtotal pericardiectomy of idiopathic pericardial effusions
18
Q

When are diuretics indicated?

A
  • Indicated in all cases with cardiogenic pulmonary oedema
  • Indicated in most cases of CHF with the exception of pericardial effusion (best treated by pericardiocentesis)
  • Large pleural effusions are best managed by thoracocentesis although diuresis can also be helpful
19
Q

What types of diuretics are normally used in CHF?

A
Loop diuretics
• Frusemide
• Torasemide
Potassium-sparing diuretics
• Spironolactone
• Amiloride
Thiazides
• Hydrochlorthiazide
20
Q

Outline dosing with frusemide

A
  • First-line choice for diuresis in dogs and cats with CHF
  • It can induce activation of the RAAS if used before the onset of CHF
  • Dose very variable: 0.5-4 mg/kg q 1-24 h (IV, SC, IM, oral). Acts within 20 minutes of parenteral administration
  • In acute CHF: 2-4 mg/kg IV, IM every1-2 hours until respiratory rate decreases
  • Chronic CHF in dogs: 0.5-4 mg /kg SID to TID. Titrate to the lowest dose adjusting for respiratory rate and prerenal azotaemia
  • Chronic CHF in cats: from 1 mg/kg every 2 to 3 days to 2 mg /kg SID to TID
  • Some venodilating effects when given slowly IV (transient deafness if given rapidly in some cases)
  • Easier to judge response to treatment with bolus dosing than constant rate infusions
21
Q

Outline the use of spironolactone in CHF

A

• Weak potassium-sparing diuretic but more importantly an aldosterone antagonist (with
effects on vasculature and myocardial fibrosis and remodelling)
• Many cardiologists will use it addition to frusemide, an ACE inhibitor and pimobendan in dogs with Stage C CHF
• A recent study in cats showed that spironolactone was beneficial in the treatment of CHF secondary to a cardiomyopathy when added to standard therapy with benazepril and frusemide
• Dose: 2 mg/kg SID with food
• Ulcerative facial dermatitis is a rare side effect seen in cats

22
Q

Outline the use of hydrochlorothiazide

A
  • Thiazide diuretics act at the distal convoluted tubule of the nephron
  • They tend to be used in refractory CHF (Stage D) in combination with other diuretics (sequential nephron blockade) and it is often available in combination with amiloride
  • Dose: 1-2 mg/kg sid to bid
  • Prerenal azotaemia is a common result of diuresis
23
Q

What are the neurohormonal blockers?

A
ACE inhibitors
• Enalapril
• Benazepril
• Ramipril
• Imidapril
Spironolactone
Beta-blockers
24
Q

Outline the use of beta blockers

A
  • Generally not recommended in dogs and cats with CHF as they reduce myocardial contractility and can exacerbate CHF signs
  • They can be effective in reducing heart rate and in the treatment of supraventricular and ventricular tachyarrhythmias in dogs and cats
  • Atenolol has been used in cats with asymptomatic HOCM and also in cats with asymptomatic HCM and ventricular dysrhythmias (dose 6.25 mg /cat SID-BID)
25
Q

What are the most used positive inotropes?

A

Pimobendan and digoxin

26
Q

What are the indications of pimobendan in cats (not licensed)

A

• In DCM and CHF, added to standard therapy with frusemide and ACE inhibitor
• In cats with HCM and other cardiomyopathies with refractory CHF with LV systolic dysfunction
NOT when LVOTO

27
Q

Outline the use of digoxin

A

• Weak positive inotropic effects
• Antiarrhythmic agent of choice in dogs with atrial fibrillation and CHF
• Narrow therapeutic/toxic window. Side effects include:
• Gastrointestinal effects: anorexia, vomiting, diarrhoea
• Arrhythmia complications: ventricular arrhythmias, bradyarrhythmias
• Side effects are more common at higher serum concentrations and most benefits occur at
lower doses
• Dose in dogs: 0.1-0.15 mg/m2 orally BID for a trough (8-12 hour post-pill) serum digoxin concentration of 0.6-1.1 mg /ml 5-7 days after starting treatment. Avoid in cats

28
Q

What are the Ca Channel blockers

A

Amlodipine

Diltiazem

29
Q

When is amplodipine used?

A
  • Vasodilator used mostly as a antihypertensive agent in cats with systemic hypertension (0.625 mg-1.25 mg/cat PO SID)
  • Some cardiologists use it in Stage D MMVD in dogs who have refractory signs of CHF for its arteriodilator properties (0.05-0.25 mg/kg PO SID)
30
Q

When is diltiazem used?

A
  • Diltiazem is an important drug for the treatment of supraventricular tachyarrhythmias in dogs and cats
  • It is often used for rate-control of atrial fibrillation in dogs at a dose of 0.5-2 mg/kg TID
  • Diltiazem also improves myocardial relaxation and has been used in cats with HCM (7.5- 15 mg/cat TID)
  • Potential side-effects at high doses include hypotension, anorexia, lethargy and bradycardia
31
Q

Aside from the main vasodilators, what else can be used?

A
  • Glyceryl trinitrate

* Sildenafil

32
Q

Outline the use of glyceryl trinitrate

A
  • Nitrate vasodilator with mainly venodilator effects
  • Given as a percutaneous ointment (handle with gloves) in hospitalised dogs and cats with acute CHF
  • Used for a short period as animals become refractory to the drug
33
Q

Outline the use of sildenafil

A

• Phosphodiesterase V inhibitor used to reduce pulmonary vascular resistance
• Used in patients with right-sided CHF due to
- Chronic pulmonary disease
- Advanced MMVD with pulmonary hypertension
• Dose in dogs (not licensed): 0.1-0.3 mg/kg BID

34
Q

Outline the use of asprin in cats

A
  • Non-steroidal anti-inflammatory drug with inhibition effect on platelet aggregation
  • Used for prevention of aortic thromboembolism in cats with left atrial enlargement and/or spontaneous contrast
  • Dose: 5 mg/cat to 5 mg/kg q 3 days with food
35
Q

Outline the use of clopidogrel

A
  • Platelet aggregation inhibitor used for the prevention of aortic thromboembolism in cats
  • It can be used on its own or in combination with low-dose aspirin
  • Dose: 18.75 mg /cat PO SID