Deja review Cardio/Renal agents - Congestive heart failure agents Flashcards
What is the cardiac output equation?
Cardiac output (CO) = heart rate (HR) X stroke volume (SV)
What is normal CO?
5L/min
What is the most common course of right sided heart failure?
Left sided heart failure
Name 3 compensatory physiological responses seen in CHF
1) Fluid retention
2) INC sympathetic drive
3) Hypertrophy of cardiac muscle
Define preload
The pressure stretching the ventricular walls at the onset of ventricular contraction, related to left ventricular end-diastolic volume pressure
Define afterload
The load or force developed by the ventricle during systole
What drugs are used to DEC preload?
Diuretics, vasodilators, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), nitrates
What drugs are used to DEC afterload?
Vasodilators, ACEIs, ARBs, hydralazine
What drugs are used to INC contractility?
Digoxin, phosphodiesterase inhibitors (amrinone and milrinone), ß-adrenoceptor agonists
What is MOA of digoxin?
Inhibition of the Na+/K+-ATPase pump which leads to positive inotropic action (via INC intracellular sodium ions that exchanges with extracellular calcium ions, resulting INC in intracellular calcium ions leads to INC force of contraction
What are the 2 digitalis glycosides?
1) Digoxin
2) Digitoxin
What are the adverse effects of digoxin?
Arrhythmias, nausea, vomiting, anorexia, headache, confusion, blurred vision, visual disturbances, such as yellow halos around light sources
What electrolyte disturbances predispose to digoxin toxicity?
Hypokalemia, hypomagnesemia, hypercalcemia
Digoxin can cause what types of arrhythmias?
Supraventricular tachycarias, AV nodal tachycardias, AV block, ventricular tachycardias, ventricular fibrillation, complete heart block
Can digoxin be used in WPW (wolf-parkinson-white) syndrome?
Np. Since digoxin slows conduction thru the AV node, the necessary pathway present in WPW is left unopposed, leading to supraventricular tachycardias and atrial arrhythmias
How is digoxin toxicity treated?
Correction of electrolyte disturbances, antiarrhythmics, anti-digoxin Fab antibody (Digibind)
What drugs can INC digoxin concentrations?
Quinidine, amiodarone, erythromycin, verapamil
What drugs can DEC digoxin concentrations?
Loop diuretics, thiazide diuretics, corticosteroids
Dpes digoxin therapy in CHF lead to prolonged survival?
No, it is of symptomatic benefit only, improving quality, but not necessarily duration of life
What classes of medications have been shown to INC survival in CHF patients?
ACEs, ARBs, ß-blockers
How does dobutamine work in CHF?
ß-adrenergic agonist (sympathomimetic that binds to (ß1 adrenoceptors) that INC force of contraction and vasodilation via INC cAMP
How do amrinone and milrinone work in CHF?
Inhibits phosphodiesterase (PDE) thus INC cAMP levels, INC cAMP leads to INC intracellular calcium, INC intracellular calcium leads to INC force of contraction, INC cAMP also leads to INC vasodilation
What are the side effects of PDEIs?
Milrinone may actually DEC survival in CHF, amrinone may cause thrombocytopenia
How do diuretics work in CHF?
DEC in intravascular volume, thus DEC in preload, reduce pulmonary and peripheral edema often seen in CHF patients
How can INC sympathetic activity in CHF be counteracted?
ß-blockers
What 2 ß-blockers have specific indications for the treatment of CHF?
1) Metoprolol
2) Carvedilol (mixed α-/ß blocker)
What is the MOA of nesiritide?
Recombinant B-type natriuretic peptide that binds to guanylate cyclase receptors on vascular smooth muscle and endothelial cells, thus INC cyclic guanosine monophosphate (cGMP) evels; INC cGMP leads to INC relaxation of vascular smooth muscle
How do ACEIs work in CHF?
Inhibition of angiotensin-II (AT-II) production thus DEC total peripheral resistance (TPR) and thus afterload prevents left ventricular remodeling
