CHF treatment Flashcards
COMMON CAUSES OF ACUTE CONGESTIVE HEART FAILURE
Acute Myocardial Infarction
Global Myocardial Ischemia (‘Stunned Myocardium’)
Acute Viral Myocarditis
Acute Valvular Regurgitation (AR, MR)
Arrhythmias - VT, VF, SVT with rapid ventricular response (WPW)
Acute Pericardial Tamponade
Massive Pulmonary Embolism
COMMON CAUSES OF CHRONIC
CONGESTIVE HEART FAILURE
Ischemic Cardiomyopathy (most common cause of CHF in US)
Hypertrophic Cardiomyopathy
Dilated Cardiomyopathy
TREATMENT OBJECTIVES IN ACUTE CHF
Early recognition and treatment
Decrease symptoms (primarily pulmonary congestion)
Increase cardiac output (Increase cardiac contractility, Reduce afterload)
why are diuretics used in CHF and how do they work
used to decrease pulmonary congestion by:
Reduce intravascular volume to reduce filling pressure (preload)
Reduce pulmonary venous pressure and interstitial pulmonary edema
Improve oxygenation
*Preload reduction may have little effect on cardiac output in patients with CHF (flat portion of Starling Curve)
diuretics commonly used in CHF
Loop and Thiazide diuretics
*** Furosemide (Lasix®) others (Bumetanide, Torsemide)
Thiazide diuretics (chlorothiazide, and chlorthalidone)
how does furosemide work
- Loop diuretic – inhibits Na+/K+/2Cl- Cotransporter in Loop of Henle
- Intravenous and oral preparations
- Rapid onset of action; relatively short duration
- Very potent!!!
How do thiazide diuretics work
- Inhibit Na+ and Cl- reabsorption in distal tubules
- Can be used in combination with loop diuretics in patients resistant to furosemide
ADVERSE EFFECTS OF DIURETICS
Overdiuresis
Hypokalemia
- Precipitate arrhythmias, especially digitalis-induced arrhythmias
Hypomagnesemia
Hyperuricemia
- Precipitate acute gout
Ototoxicity and Hearing Loss
Allergies (Loop and Thiazide diuretics are sulfa drugs)
Diuretic Resistance
- Reduce GFR because of volume reduction
- Overcome by using drugs in combination
what is the function of nitroglycerine and other organic nitrates in CHF
Venodilate (reduces venous return, reduced preload, reduced afterload)
NISERITIDE (Natricor ®) MOA
Human Recombinant Brain Natriuretic Peptide (hBNP)
“Normally” produced by ventricular myocardium in response to “chronic” stretch
Activates vascular smooth muscle NPR1 and NPR2 receptors
Raises cGMP levels in VSMC-vasodilation
Decreases Na reabsorption in the Distal tubule
Therefore NISERITIDE induces both vasodilatation and natriuresis
overall effect of NISERITIDE (Natricor ®)
NISERITIDE induces both vasodilatation and natriuresis
what is the affect of CHF on contractility
contractility is decreased in many forms of acute CHF
Acute reduction in LV contractility (for example, global ischemia, acute MI)
Chronic reduction in LV contractility (for example, chronic valvular regurgitation, ishcemic cardiomyopathy)
what types of drugs are used to increase contractility in CHF (inotropic agents)
Beta Adrenergic Agonists
- Isoproterenol - Dopamine - Dobutamine - Norepinephrine
Phosphodiesterase Inhibitors
- Inamrinone - Milrinone
what do activation of B1 receptors in the heart cause
increased cAMP (through Gs) which results in
- Increased Opening of L-type Ca channels
- Increased Reuptake of Ca into SR stores
- Increased Pacemaker Current
- Increased Rate of Conduction
what drugs increase cAMP levels
Beta Adrenergic Agonists: Isoproterenol (nonselective β1, β2-ARs) Dopamine (low-dose β1-selective; high dose α1-AR) Dobutamine (β1-selective) Norepinephrine (nonselective)
Phosphodiesterase Inhibitors:
Inamrinone (aka Amrinone)
Milrinone