management of heart failure Flashcards
what physiological events occur during heart failure
- activation of RAAS = salt/water retention
- fluid build up in vessels
- venous pressure rises
- fluid pushed out of veins and capillaries
- congestion and oedema
- but CO and BP are restored
maintenance on BP is highest prority
other systems activated:
- increased production of anti-diuretic hormone = water retention
- natriuretic peptides triggered by arterial stretch, stimulate natriuresis (removal of salt and therefore water to reduce arterial stretch
what is decompensation
- failure to compensate for functional overload caused by disease
- eventually patient deteriorates
- leading to congestive heart failure and disease progression
compare backward vs forward heart failure
backwards failure:
- congestion of veins (oozing out as oedema)
- most common in veterinary patients
forwards failure:
- poor perfusion
- less common (chronic, more compensation)
what occurs when you have left sided heart failure
- congestion of pulmonary venous circulation
- pulmonary venous circulation drains fluid from the lungs
- if this does not work, leads to pulmonary oedema (seen as radiopaque lung fields)
what occurs in right sided heart failure
- congestion of systemic venous circulation
- systemic venous circulation drains fluid from body
- leads to accumulation of fluid in abdominal cavity (ascites)
- can see jugular vein without raising it due to increase in venous pressure
compare left and right heart failure
- L sided heart failure is more common than R
- diseases affect left more than right
- L side of heart is high pressure = effects of disease more obvious and dramatic and accumulation of fluid in the lungs is life threatening
- fluid in abdomin doesnt present with as dramatic life threatening clinical signs
how do patients with heart failure typically present
- congestive heart failure
- collapse
- heart disease found by chance
- non-specific malaise/weight loss
heart disease does not always equal heart failure
explain why congestive heart failure severity varies
- clinical signs develop with time
- patient compensates for disease intitally
- gets progressively worse
- clinical signs vary
what is the ACVIM consensus for scoring heart disease
stage A: patients at high risk of heart disease but have no identifiable structural disorder of the heart (breed risks)
stage B patients with structural disease (murmur) but no clinical signs
- B1: asymptomatic patients with no radiogrpahic or echocardiographic evidence of cardiac remodelling
- B2: asymptomatic patients with radiographic or echocardiographic evidence of left-sided heart enlargement
stage C: patients with past or current clinical signs of heart failure associated with structural heart disease. heart disease present evident of limited exercise intolerance that progressively worsens. signs evident with mild excersise = moderate
Stage D: patients with end stage disease with clinical signs of heart failure that are refractory to standard therapy. patient has obvious clinical signs with minimal exercise that worsens (maybe to point where they have clinical signs even at rest. progressively worsens, possibly until death
list factors that require consideration when considering treatment of patients with heart disease
- primary causes of heart disease (can we treat it specifically? valve degeneration? cardiomyopathy? do we know cause?)
- non-specific treatment of the primary disease
- treatment of congestive heart failure
- identify dysrhythmias and treat if indicated
- identify complicating and co-existing factors (make sure kidney can take treatment and monitor for degradation of kidney function, dont send into kidney failure)
- regular reassessment
- what does the owner want
what drugs improve contractility
positive inotropes
- pimobendan (vetmedin)
- dobutamine
- digoxin
what drugs help relax heart (to treat hypertrophic disease)
positive lusitropes
- calcium channel blockers (diltiazem, verapamil)
- beta blockers (propranolol, atenolol)
how do you treat an animal in stage B1 heart failure
- asymptomatic disease with no cardiac remodelling
- no treatment but consider weight control, regular reassessment (q 6 mo) and client education (signs to look for in progression)
how do you treat an animal in B2 stage heart failure
- asymptomatic disease with cardiac remodelling
- same as B1, weight control, regular assessment and client education
- EPIC study suggests giving pimobendan can be beneficial in slowing progression, increasing QOL and length of life (increases contractility)
how do you treat stage C heart failure
- signs due to fluid accumultion
- cough/breathing problems in LHF, fluid accumulation in body cavities in RHF)
- problem with reversing or reducing clinical signs as stopping cycle can interrupt compensation of BP maintenance and perfusion leading to kidney failure
- continue with pimobenden
- excersise regime (consistent and within capacity)
- aspirate fluid
how does the RAAS system work
system activated in heart failure
conversion of angiotensin I to II is done by ACE, blocking this prevents RAAS from occuring
