30 - 31 - Heart Failure Drugs Flashcards
Which factors control cardiac output (CO)?
CO = HR x SV
- Heart rate
- Stroke volume
Or anything that changes either the HR or SV
What things affect the stroke volume? Increase or decrease?
Stroke volume
- Increased contractility increases SV (note that parasympathetics decrease contractility and sympathetics increase contractility)
- Increased preload (due to increased ventricular filling) increases SV
- Increased afterload (due to increased arterial pressure) decreases SV
What things affect heart rate?
Heart rate
- Parasympathetics decrease HR (negative chronotrope)
- Sympathetics increase HR (positive chronotrope)
Describe the Frank-Starling relationship in different myocardial contractile statuses
- Stroke volume should increase as ventricular EDV and stretching of the myocardium increases
- An example would be during exercise in a healthy individual - Higher blood flow, higher EDV, higher SV, able to keep up with demand
- This near-linear relationship turns into a “hump” shape in heart failure and fatal myocardial depression patients - there comes a point where the strove volume begins to decrease despite the EDV increasing
- This means blood is sitting in the heart and is not getting pumped out to meet the body’s demand
Describe the ACC/AHA classification system for HF
Four stages
- A: high risk for developing HF
- B: asymptomatic HF (pre-HF)
- C: symptomatic HF
- D: refractory end-stage HF
Describe stage A - high risk for developing HF
- Hypertension
- CAD
- Diabetes mellitus
- Family history of cardiomyopathy
Describe stage B - asymptomatic HF (pre-HF)
- Previous MI
- LV systolic dysfunction
- Asymptomatic valvular disease
Describe stage C - symptomatic HF
- Known structural heart disease
- Shortness of breath and fatigue
- Reduced exercise tolerance
Describe stage D - refractory end-stage HF
- Marked symptoms at rest despite maximal medical therapy (e.g. those who are currently hospitalized or cannot be safely discharged home from the hospital without specialized interventions)
Which drugs are recommended for stage A?
- ACEi or ARB: to address vascular disease, diabetes, hypertension
Which drugs are recommended for stage B?
- ACEi or ARB for recent/remote MI, asymptomatic LVD, hypertensive, LVH
- Beta blocker for recent/remote MI and asymptomatic LVD
Which drugs are recommended for stage C?
- ACEi or ARB - all pts. unless cx
- Beta blocker - all pts. unless cx
- Diuretics - for fluid retention
- Aldosterone antagonist - for symptomatic LVD, post-MI HF, LVD
- Hydralazine and nitrates - for symptomatic HF (AAs)
- ARB and ACEi - for symptomatic HF
- Digoxin - for symptomatic HF, atrial fibrillation
Which drugs are recommended for stage D?
- ACEi or ARB - for all pts. unless cx
- Beta blocker - for stable NYHA class IV
- Diuretics - for fluid retention
- Digoxin - for afib with rapid ventricular response
- Positive inotropes - for bride to transplantation or end of life
What is the effect of positive inotropic agents on hemodynamics?
Positive inotropic agents, such as cardiac glycosides or dobutamine, move patients to a higher ventricular function curve, resulting in greater cardiac work for a given level of ventricular filling pressure
What is the effect of vasodilators on hemodynamics (i.e. ACEi or nitroprusside)
- Improve ventricular function while reducing cardiac filling pressure
