Heart Failure Drugs Flashcards
preload
volume of blood in the ventricles at the end of diastole which stretches the ventricles
What drugs are used to reduce preload?
DIURETICS (and sometimes nitroprusside/nitroglycerin)
Loop diuretics MOA
inhibit the Na/K/Cl cotransporters in the thick ascending limb of the Loop of Henle
2 Examples of Loop Diuretics
1) Furosemide (Lasix)
2) Torsemide
Which is more potent - furosemide or torsemide?
torsemide (10-20x) - used more in end stage or refractory cases of heart failure
Thiazide diuretic MOA
inhibits the reabsorption of Na and Cl in the distal tubule
Main side effects of Diuretic Therapy?
dehydration and electrolyte abnormalities
Spironolactone
competitively antagonizes aldosterone by downregulating NaK pump and therefore blocking Na reabsorption in the distal convoluted tubule
Why is spironolactone considered a weak diuretic?
not that much sodium is really reabsorbed in the collecting duct and that’s its main MOA
Inotrope
agent which alters the force of heart muscle contractility
Negative Inotrope Definition and Two Categories
decreasing the force of muscular contractions
1) beta blockers
2) calcium channel blockers
Clinical Scenarios for Negative Inotropes
Hypertrophic Obstructive Cardiomyopathy, Stenoses, tachyarrhythmias
Positive Inotrope Definition and Three Examples
Increase the strength of muscular contraction; also reduces mitral regurgitation and pulmonary edema
1) Dobutamine
2) Pimobendan
3) Digoxin
5 Goals of Positive Inotrope
IMPROVE:
1. Contractility
2. Cardiac output
3. Blood pressure
4. Clinical signs
5. QOL
Which positive inotrope is given IV?
dobutamine
Pimobendan
the first line therapy for heart failure - an oral medication that does NOT cause significantly increased calcium!
Dobutamine
a continuously administered IV medication (positive inotrope) for severe cases of heart failure
Cardiac Output equation
heart rate times stroke volume
Pimobendan MOA
inhibits phosphodiesterase III making it a balanced arterial and venous vasodilator, making the heart more SENSITIVE without increasing levels of calcium
Phosphodiesterase Inhibtors
prevent conversion of cAMP to AMP; more cAMP means more contractility
Afterload
the pressure the ventricle must overcome to circulate blood (left –> aorta or right –> pulmonary artery)
Is afterload increased or decreased when blood pressure is high?
increased
Is afterload increased or decreased during vasoconstriction?
increased
Ideal systemic blood pressure?
110-130mmHg
Systemic Afterload Reducers
work on the left side of the heart; Amlodipine, angiotensin receptor blockers (drugs that end in -sartin), and ACE inhibitors (Enalapril, Benazepril, etc)
Ideal pulmonary pressure?
15-25mmHg
Overlapping mechanisms which control blood pressure?
neuro, renal, vascular, hormonal
Beta receptor on the heart?
b1
Beta receptor on the lungs?
b2
Nucleus solitarius
termination of afferent stimuli (from vagal and glossopharyngeal nerves of the autonomic nervous system) in the medulla
baroreceptors
part of the autonomic nervous system and participate in the feedback loop which controls blood pressure
In circulation, which is higher under normal conditions - epinephrine or norepinephrine?
epinephrine
Amlodipine
calcium channel blocker
Sildenafil
stimulates the nitric oxide pathway via inhibiting PDE5; treats pulmonary hypertension
RAAS
Renin Angiotensin Aldosterone SYstem
End products of RAAS?
aldosterone and angiotensin II
How to block RAAS?
ACE inhibitors, angiotensin receptor blockers, spironolactone
Side effects of ACE inhibitors?
azotemia
Beta blockers are what drugs?
the -olols (like atenolol); helps chill out the sympathetic nervous system
