Pharma Lab 4 Congestive Heart Failure

Question 1

what is congestive heart failure?

Answer 1

fluid build up in the heart which causes inefficient pumping

Question 2

what can cause congestive heart failure?

Answer 2

acute development
chronic development
can be inherited or congenital
peripheral circulation disturbance
cardiac origin
systemic diseases

Question 3

is CHF more common is cats or dog

Answer 3

more common in dog

hypertrophic cardiomyopathy is more common in fe. due to thrombosis in iliaca usually. treat with clopidogrel.

Question 4

in order to treat CHF what must be done to the preload, contractility and afterload?

Answer 4

preload: decrease
afterload: decrease
contractility: increase

Question 5

what drug groups can be used to decrease preload?

Answer 5

• Diuretics (incr H2O excretion)
• ACE inhibitors (inhibits effect of renin-angiotensin system - H2O retention + vasocon inhibited, causes vasodilation and increased H2O excretion).
• Pimobendan (PDE inhibitor - vasodil + +ve ionotropic effect).

Question 6

what drug groups can be used to decrease afterload?

Answer 6

• Vasodilators
• ACE inhibitors (inhibits effect of renin-angiotensin system - H2O retention + vasocon inhibited, causes vasodilation and increased H2O excretion).
• PDE inhibitors (vasodil)

Question 7

what drugs can increase contractility?

Answer 7

Pimobendan: via an increase Ca sensitivity in myocardial cells (+ve ionotropic effect) + vasodilation.

Digoxin: +ve ionotropic effect - makes contraction stronger .

Question 8

how many stages are there in CHF?

Answer 8

4 (5) stages:
A
B1 + B2
C
D

Question 9

What is Stage A and how can it be treated?

Answer 9

Stage A
- No issue: animal not effected.
or
- Breed is genetically predisposed to CHF, requires examination every 6 months to ensure disease does not begin/persist. e.g. King Charles

Question 10

What is Stage B1?
How can it be treated?

Answer 10

Stage B1: there is an issue but no clinical signs.

A murmur can be heard but no clinical signs or heart failure / enlargement.

Regurgitation: can cause a murmur to develop, if a valve of the heart does not close properly, blood will flow back into the orifice -> regurgitation.

Treatment: No diet or treatment is necessary but monthly evaluation via US and xray is necessary.

Question 11

What occurs in Stage B2?
How can it be treated?

Answer 11

Stage B2: heart murmur can be heard, heart remodelling can be seen (enlargement and abnormal shape - trachea elevated). no clinical signs yet.

Treatment:
PIMOBENDAN. Increases Ca2+ conc in myocardial cells giving a +ve ionotropic effect.
it is also a PDE inhibitor causing vasodilation.
Prevents remodelling.
Dose: 0.1 - 0.3 mg/kg SID 1hr prior to feeding.

DIET: Low Na (Na retains water), high K+, high Mg2+ (lost due to diuretics), high PUFA (heart requires energy)

Question 12

What occurs in Stage C?
How can Stage C be treated?

Answer 12

Stage C
Clinical sings + remodelling present:
- poor posture
- laboured breathing
- cachexia

Treatment: use x5 in combo
- ACE INHIBITORS: inhibits effect of renin-angiotensin system - H2O retention + vasocon are inhibited, causes vasodilation and increased H2O excretion thus decreases PL + AL.

• FUROSEMIDE: loop diuretic, increases water excretion. Which can activate renin-angiotensin system (RAS), aldosterone escape is also activated (completes RAAS) therefore requires the lowest possible dose; 1 - 2 mg/kg.
• SPIRONOLACTONE: aldosterone antagonist, needed bc furosemide can dehydrate the body and so activate the aldosterone escape, which will prevent H2O excretion (works with RAS as RAAS). Spir can also prevent remodelling of the heart - ald can act on myofibroblasts and cause collagen production thus preventing the heart from expanding. It is also a weak diuretic.
• PIMOBENDAN: Increases Ca2+ conc in myocardial cells giving a +ve ionotropic effect (makes contraction stronger), thus increasing AL.
  It is also a PDE inhibitor causing vasodilation.
  Prevents remodelling.
  Dose: 0.1 - 0.3 mg/kg SID 1hr prior to feeding.
• SILDENAFIL: found in viagra. A PDE inhibitor therefore used against pulmonary hypertension (in lungs and other tissues) as it causes vasodilation.

Question 13

What occurs in Stage D?
How can Stage D be treated?

Answer 13

Clinical Signs + remodelling!

GIVE ALL DRUGS GIVEN IN STAGE C!!

BUT:
- Increased dose of FUROSEMIDE (+spirono) (8mg/kg - not in fe as they are very sensitive so remain at 1-2mg/kg).

• Increased dose of PIMOBENDAN (give IV first, if animal survives can then give increased dose PO).
• AMLODIPINE: if hypertension persists we can give this drug, it is a Ca2+ channel blocker to decrease BP. Can also give another ACE inhibitor or Angiotensin II receptor antagonist (Telmisartan /
  losartan).
• HYDRALAZINE: SM relaxant causing vasodilation - little info available in vet usage.
• DIET: Low Na+, high K+, high Mg2+, PUFA. (K + Mg lost due to diuretics).

Question 14

How can we treat ACUTE heart failure?

Answer 14

Quick diagnosis is needed!

• Oxygen via tube/ mask.
• Sedation: Acepromazine (help to decr bp), can add butorphanol (opioid).
• HIGH dose of DIURETICS (furosemide) + VASODILATORS (pimo) to decrease the PL + AL.
• HIGH dose of +VE IONOTROPIC AGENTS to increase contractility (furosemide or epinephrine in severe cases).

if arrhythmia is present it must be treated.

Question 15

How is arrhythmia treated?

Answer 15

Bradycardia: give atropine
Tachycardia: give lidocaine