drugs for HF Flashcards
what are signs of left sided congestive HF
- pulmonary venous congestion
- edema (cough, tachypnea, dyspnea, orthopnea, pulmonary crackles, tiring, hemoptysis, cyanosis)
chronic L sided CHF can lead to..?
pulmonary hypertension and R sided HF signs
signs of R sided CHF
systemic venous hypertension with resting jugular venous distension, hepatic congestion, pleural effeusion, ascites, small pericardial effusions and sometimes subcutaneous edema
what are the diuretic drugs (3)
- Furosemide
- Spironolactone
- Hydrochlrothiazide
what are the ACE inhibitors (4)
- Enalapril
- Benazepril
- Lisinopril
- Ramipril
what drug is a calcium sensititzer
Pimobendan
what drug is a digitalis
Digoxin
what are the sympathomimetic drugs (2)
dobutamine
dopamine
what drugs are beta blockers (3)
atenolol
metoprolol
propranolol
what drug is both a beta and alpha blocker
Carvedilol
what drugs are Ca channel blockers
Diltiazem
Amlodipine besylate
what is the major determinant of CO
preload; filling pressure of heart
resistance that ventricles need to push through to eject blood
afterload
what things regulate contractility
- filling pressure (afterload)
- sympathetic tone
HR is determined by ______ tone
vagal
Type of HF: severe cardiogenic pulmonary edema
Acute HF
type of HF: Pleural effusion and ascites (fluid in abdomen)
chronic HF
what is the goal when treating hypertrophic cardiomyopathy
you want to avoid sustained elevations in HR = improve cardiac relaxation, want to increase filling time and reduce ischemia
ACE inhibitor+furosemide
hypertrophic cardiomyopathy
affects the Left ventricle; impairs ventricular filling
what drugs would be useful in treating hypertrophic cadiomyopathy and why
- ACE Inhibitor - reduces the effects of neurohormonal activation (dilates arterioles and venules)
- furosemide - loop diuretic for cardiogenic edema/effusion
what is cardiac tamponade
impaired filling of ventricles
abnormal amts of fluid accummulate in the pericardial sac, compressing the heart so that it cannot fill properly - causes a huge drop in bp
how is cardiac tamponade treated
pericardiocentesis w/ or w/out subsequent pericardiectomy
what is the purpose of diuretic drugs
control edema/effusions
loop diuretic used in animals w/ cardiogenic edema or effusion
Furosemide, a loop diuretic
the smallest ED of this drug are used for chronic HF but agressive therapy w/ this drug is indicated for acute fulminant pulmonary edema
Furosemide
this drug should not be used as a monotherapy txt for CHF
Furosemide
drug primarily used to reduce exercise induced pulmonary hemorrhage in race horses
Furosemide
adverse effects of furosimide
excessive fluid / electrolyte loss
Potassium sparing loop diuretic that can be an adjunct therapy for chronic refractory HF; all use is ELDU
Spirolactone
refractory HF
end stage or chronic
what drug is absolutely contradicted in hyperkalemic patients
Spirolactone
adverse effects of Spirolactone
related to excess K retention and GI disturbances
Spirolactone use in patients receiving _____ or ________ is sketchy
ACE inhibitor, K supplement
drug recommended for dogs and cats that have become refractory to furosemide and can be an adjuncitve txt for hyperkalemic periodid paralysis in horses (HyPP)
Hydrochlorothiazide
(Thiazide diuretic)
how do ACE inhibitors block the action of ACE
block conversion of inactive precursor peptide (Angiotenis I) into acive Angiotensin II
these drugs decrease the effects of the RAAS cascade
ACEI
More ACEIs are _____ that are converted into their active form in the liver
prodrugs
why might use of ACEIs in patietns with liver dysfunction not be as slay as in a patient with a normally functioning liver
ACEIs have to be converted from prodrug into active form in the liver
ACE inhibitors target what enzyme
Angiotensin converting enzyme (kininase II)
ACEIs have what effect on arterioles and veins
vasodilation
vasodilating effects of ACEIs can be enhanced by….
bradykinin
(ACE degrades bradykinins) so ACEIs keep it around
these drugs are considered as the first choice agent in the management of systemic arterial hypertension
in dogs
ACEIs
in addition to their use in chronic management of most causes of chronic heart failure, these drugs might also be useful for the treatment of renal failure in cats and slowing the progression of chronic renal failure in dogs
ACEIs
what are the adverse effects of ACEIs
- hypotension
- GI upset
- renal function deterioration, and hyperkalemia (especially when used with a K+ -sparing diuretic or K+ supplement).
how do you proceed if a patient becomes azotemic while on ACEIs?
diuretic dosage is decreased; then if needed ACEI dose decreased or stopped
Drugs that are ACEIs have the ending…
-prils
* enalapril
* benzaepril
* lisinopril
* ramipril
this drug increases myocardial contractility by increasing myofilament sensitivity to Ca2+
Pimobendan
what is the labeled use of pimobendan
for use in dogs with HF from dilated cardiomyopathy or chronic mitral valve disease
Use in cats is ELDU
how does pimobendan cause vasodilation
inhibits phosphodiesterase III (which breaks down cAMP)
how does pimobendan cause increased mycaridal contractions
increases myocardial cAMP levels which activates protein kinase A, PKA then activates L-type Ca2+ channels which ↑ myocardial contractions
how do loop diuretics (furosemide) work
- they inhibit the Na/K/Cl cotransporter causing ions to accumudate in medulla of kidney
- less water can be reabsorbed, lowers bp and increases urination
what ACEI is labeled for use in dogs
Enalapril
how do thiazide diuretics work
- inhibiti the Na+/Cl− cotransporter in the renal distal convoluted tubule
- decrease Na reabsorption,** decreasing water reabsorption**
what is the main difference b/w Enalapril & Benazepril (ACEIs)
enalapril is mainly cleared (95%) by the kidney while benazepril is cleared by both renal (45%) and hepatic (55%) routes.
what are the effects of Ca sensitizers (Pimobendan)
- increases myocardial contractility
- vasodilation
How does Pimobendan (Ca sensitizer) increase myocaridal contractility
- by increasing myofilament sensitivity to Ca
- by increasing myocardial cAMP levels –> activates PKA, PKA activates L-type Ca channels –> increases myocardial contractions
how does Pimobendan (Ca sensitizer) cause vasodilation
it inhibits phosphodiesterase II which breaks down cAMP
what is the indicated use for Pimobendan
HF from dilated caridomyopathy or chronic mitral valve disease
where is Pimobendan metabolized
liver
excreted in feces
Adverse effects of Pimobendan
- reduced appetite, lethargy, D+, dyspnea
- azotemia if underlying HF
what is the primary use for Digoxin (digitalis)
atrial fibrilations; has antiarrythmic effects
what are the antiarrythmic effects provided by Digoxin
- increased parasympathetic tone to sinus & AV nodes and atria
- improves arterial baroreceptor sensitivity to increase vagal tone in HF
how does digoxin cause an increased intracellular [Ca]
competitively inhibits Na/K ATPase pump, decreasing extracellular Na transport causes intracellular Ca accumulation b/c Na/Ca exchange is decreased
what patients is Digoxin use contraindicated in
cats w/ hypertrophic cariomyopathy
what are the most common adverse effects of Digoxin
- cardiac toxicity
- stimulation of various arrythmias –> sinus bradycardia
what is the treatment for digitalis toxicity
oral or IV K+
NEVR Ca
also: lidocaine, phenytoin, propranolol
what is the interaction b/w digoxin and K+
they inhibit each other’s bidnding to the NA/K ATPase receptors; K+ counteracts digitalis toxicity; K+ reduced abnormal caridac automaticity
what is the interaction b/w Ca and digoxin
Ca enhances digitalis toxicity
Mg and digitalis (Digoxin)
decreases digitalis toxicity
indicated use of sympathomimetics (Dobutamine & Dopamine)
- myocardial failure
- hypotension that doesn’t respond to fluid loading
what are the effects of Dopamine at low, medium and high doses
- low: stimulate D1 receptors - vasodilation in kidney
- medium: stimulate β receptors - positive inotropic effect
- high: stimulate α receptors - peripheral vasoconstriction in dogs
dobutamine is a synthetic analog of…
dopamine
what is the effect of dobutamine at low infusion rates
- stimulates B receptors
- increased contractility with minimal effects on HR/BP
adverse effects of sympathomimetics
- arrhythmias
- increased myocardial O2 demand
what interactions lead to increased digitalis toxicity
- hypokalemia - diurects, D+
- β antagnosits - decrease SA/AV node activity
- Ca+ channel blockers - decrease contractility
- decrease plasma binding proteins - increase toxicity
- decreased renal clearance
serum digoxin concentrations are increased in cats and dogs with ____ dysfunction
reanl
reduced total body clearance & volume of distribution
