Congestive Heart Failure Flashcards
Test 2
What is heart failure?
Heart fails to meet the metabolic demands of tissues
What is Congestive Heart Failure?
-Increased LV pressure at end diastole
-Increased pulmonary pressure and results in pulmonary edema
What is the most common cause for CHF?
CAD - Coronary artery disease
What are the 2 types of CHF?
Systolic - ejection problem
Diastolic - filling problem
What type of medication do you give for systolic HF?
Diuretics
positive iontropes
What type of medication do you give for diastolic HF?
CCB
not positive iontrops
What are the 4 factors of cardiac performance? How are these altered in HF?
- Preload
- Afterload
- Contractility
- HR
Define the Starling law
Strength of contraction increases when stretched
The more blood is in the heart because it is congested… the harder its gonna have to pump
Describe the strategies and list the major drug groups used in the treatment of acute heart failure and chronic failure.
- Calcium (Ca-Cl; Ca-gluconate)
- Diuretics
- Cardiac glycosides (digoxin)
- Positive inotropes
- PDE3 Inhibitors (milrinone) — >Prevents breakdown of cAMP = More cAMP = more forceful contraction
Draw the molecular mechanisms controlling normal cardiac contractility.
a. Voltage-gated calcium channels open
b. calcium enters cell
c. Ca binds to channel in SR,
d. Ryanodine receptors open causing release of stored calcium
e. Bathes troponin-tropomyosin complex in Ca
i. Dissociates from actin
f. Frees actin to interact with myosin
i. ATP; cross-bridge cycling
ii. Contraction
g. SERCA pumps Ca back into SR
h. Na/Ca exchanger on cell membrane
i. 3 Na in for 1 Ca out
ii. Restores Ca balance to normal to pepare for next AP
i. Na/K/ATPase
i. Restores Na balance
Drugs: Digoxin
Cardiac glycoside
Positive inotrope
PROTOTYPE
Digitalis family - foxglove plant
Narrow therapeutic index
Inhibits Na+/K+ ATPase pump
Reverses Na/Ca exchange pump
65-80 PO bioavailability
Decreases QT
Tx: Heart failure , Afib
What plant is digoxin from?
Foxglove plant
What drug inhibits Na/K ATPase pump?
Digoxin
How does Digoxin affect ions?
Hyperkalemia
Hypercalcemia
Hypomagnesia
Drugs: Milrinone
Phosphodiesterase Inhibitors
PDE3: enzyme that inactivates cAMP and cGMP
Positive inotropic without inhibiting Na/K/ATPase
Increases/prolongs Ca
Main action from vasodilation
Explain the beneficial effects of diuretics, vasodilators, ACE inhibitors, and other drugs that lack positive inotropic effects in heart failure
- ACE inhibitors (-pril): Reduce compensatory responses to failure; Reduce afterload
- ARBs (-sartan): Reduce afterload
- Vasodilators: Reduction in preload & afterload
Discuss the reasoning behind giving beta-blockers for heart failure.
Beneficial for patients with diastolic failure. diastolic HF is a filling problem. Decreasing heart rate allows more time for filling the ventricles.
What do diuretics do?
Reduce salt and water retention –>
- reduces preload
- edema
- cardiac size
improves overall heart efficiency
-pril
ACE inhibitor
-sartan
ARBs
What does a vasodilator do in heart failure?
reduce preload/afterload
What medications do you want to avoid in HF?
NSAIDs
Thiazolidinediones
Metformin
Why cant you take metformin when you have HF?
Lethal lactic acidosis
Tx for acute HF include IV:
Diuretics
Dobutamine
Vasodilators
