Heart Failure Drugs

Question 1

Therapy for each stage

Answer 1

Stage A: ACEI or ARB
Stage B: ACEI or ARB, Beta blocker
Stage C: ACEI or ARB, beta blocker, diuretic, aldosterone antagonist, hydralazine & nitrates, digoxin
Stage D: ACEI or ARB, beta blocker, diuretic, digoxin, positive ionotrope

Question 2

Digoxin

Answer 2

Cardiac glycoside
Mechanism: blocks Na+-K+ ATPase–>increase cytosolic Na+–>decrease Na+-Ca2+ exchanger–>influx Ca2+–>increase contractility

Positive ionotropic effect: decrease EDV and ESV, decrease pulmonary and systolic venous pressure, prevent reflex vasoconstriction
(+) vagal effect: decrease AV conduction, increase PR interval (ERP), decrease QT (ADP)
Increase coronary flow–>decrease hypertrophy
Decrease renal resistance
Proarrhythmic (sT depression)

Pharmacokinetics: excreted by kidney, T 1/2=3638 hrs, low margin of safety

Adverse effects: hypokalemia and acid base disbalance worsen side effects, arrhythmias, visual/ neuro disturbances, anorexia, nausea, vomiting

Use: CHF with AF

Correct elevation: cholestyramine, digoxin immune Fab (des-IgG)

Question 3

Inamrinone

Milrinone

Answer 3

Phosphodiesterase 3 inhibitor

Mechanism: increase cAMP intracellularly–>increase Ca2+–>increase contractility

CV effects:
Stimulate contractility
Accelerate relaxation
Balance arterial and venous dilation
Decrease TPR, PVR, LV, RV filling pressures-->increased cardiac output 

Use: short half-life–>short term support in CHF