Therapuetics NOT COMPLETE Flashcards
4 stages of treatment of CV disease
- Correctly ID underlying disease
- Stage severity of disease (which Tx and aims?)
- Apply EBVM
- Absence of best-evidence - make an informed and rational decision on basis of type of signs shown and type of therapy most effective
Which species are commonly treated for heart failure?
Cats and dogs
- limited literature on treatement of other species
Egs. of classification systems for staging severity of heart disease?
- New york heart association
- INternational small animal cardiac health council
- ACC (american college of caridology)
What are the simple stages of CV disease?
- disease no compensiation
- disease and compensation
- congestive heart failure with clinical signs of this
How may heart failure be characterised by pathophysiology?
- ^ preload (^ retention of fluid)
- ^ afterload (vasoconstriciton or narrowing of OFT)
- impaired inotropy
- impaired luisotropy
- abnormalities of rate and rhythm
Which drugs have good evidence for their use?
> MVD dogs - pimobendan, ACEI, sprionolactone
DCM - pimobendan, ACEI
HCM cats - ACEI
Classes of diuretic - which are most commonly used?
> loop diuretics - frusemide (commonest) - torasemide (end stage only if refractory to frusemide) > thiazides - chlorothiazide - hydrochlorothiazides > K+ sparing - spironolactone - amiloride
What is he site of action of various diuretics?
- CA inhibitors: PCT
- Frusemide: loop
- Thiazides: DCT
- K+ sparing: collecting duct
How is diuretic tx starte and progressed?
- start single agent - frusemide 1-2mg/kg oral BID/TID
- administer at higher doses and IV
- Introduce 2nd diuretic - sequential blockade (spironolactone)
- swap to torasemide
What are the risks of diuresis?
> hypovolaemia - excessive diuresis > Hypotension - reduction of cardiac output > Electrolyte disturbances - K, Mg, Na > Stimulation of RAAS
How does response in Na gain change over time with diuretic tx?
Returns to equilibrium (ie. has less effect over time)
Eg of venodilators?
glyceryl trinitrate
- percutaneous
Eg. of balanced vasodilators?
- ACEI
- Pimobendan
- Nitroprusside
What is afterload? How is afterload reduction acheived?
Peak ventricular wall tension during systole
- determined by resistance to ejection from the ventricle
- ^ systemic vascular resistance
- obstruction of outflow tracts associated with high resistance to ejection (AS/PS)
> arteriodilators (unless fixe obstruction)
How can afterload affect mitral regurgitant fraction??
decreased afterload decreased regurgitant fraction
Risks of afterload reduction?
Under perfusion of CNS, coronary circulation and renal blod flolw
Agents for afterload reduction?
- ACEI
- Pimobendan
- Others
> Ca channel blockers eg. Amlodipine
> xanthines
> alphablockers - Ateriodilators eg. hydralazine
What are patients described as cold or wet?
- cold = v output
- wet = congested
> we want patient to be warm and dry!
Which drugs can convert a patient from cold to warm?
- inotropes
- afterload reduction
- anti-arrythmics
Which drugs can convert a patient from wet to dry?
- diuretics (excrete Na)
- preload reduction
What is the most common, main tx of congestive heart failure?
Diuretics
What effects does spironolactone have?
- blocks aldosterone R
- v fibrosis through other mechanisma
How do diruetics work and what effect does this have on their use clinically?
- multiple regions of kidney
- will become refractory to drugs as further downstream adaptations occour, and sodium levels will return to a close to previous level after initial major drop
> diuretics must be maintained infinitely
> sequential bockade usage of diuretics strting with PCT -> loop -> DCT -> collecting duct based drugs
How can treatment of cardiac disease be managed?
- v preload (v fluid volume, v venous tone)
- v afterload (arterial tone)
- imprve systolic function or diastolic function
- optimise cardiac rate or rhythm
Give a specific disease where afterload reduction is particularly useful
Mitral valve disease (will v regurgitation fraction)
Which diseases will benefit from improving systolic fucntion?
- DCM
- late stage MVD
When would imprived diastolic function benefit the patient?
- hypertrophic cardiomyopathies
- fibrosis
What kind of drugs can assist with diastolic function?
- hasten relaxation (calcium channel blockers)
- slow heart rate (b blockers)
- reduce fibrosis (ACEI)
See lecture for table of preload/afterload/systolic/diastolic/rate and rhythm/blot clot prevention drugs
