Heart Failure - Auchampach Flashcards
What is heart failure?
Inability of the heart to pump blood equal to the metabolic rate of the body
What is the formula for cardiac output?
CO=heart rate*stroke volume
What factors influence stroke volume? Do they increase or decrease stroke volume?
Contractility- Increase
Preload-Increase
Afterload-Decrease
How is ‘preload’ measured?
Left Ventricle End Diastolic Volume (or pressure?)
IE: how much blood can be loaded into the left ventricle
What is afterload?
Resistance the ventricle overcomes to empty it’s contents
IE: the pressure in the aorta
What can change contractility?
Availability of intracellular calcium
What is compliance?
The change in pressure caused by an increase in volume
When does isovolumic contraction occur?
answer for the left side of the heart
After the closure of the mitral valve
When does isovolumic relaxation occur?
answer for the left side of the heart
After the closure of the aortic valve
What are three general causes of heart disease?
Impaired Ventricular Contractility
Increased Afterload
Impaired Relaxation/Filling
What are two ways to classify heart failure? Which typically combine?
Diastolic dysfunction vs Systolic dysfunction
Reduced Ejection Fraction vs Preserved Ejection Fraction
Diastolic dysfunction usually pairs with preserved EF
Systolic dysfunction usually pairs with reduced EF
What are some causes of increased afterload?
Hypertension
Aortic Stenosis
What are some causes of impaired contractility?
Coronary Ischemias (transient or infarction)
Overload caused by regurgitations
Cardiomyopathy
What are some causes of impaired relaxation/filling?
Left ventricle hypertrophy
Myocardial fibrosis
Pericardial constriction/tamponade
What is unique about the right side of the heart? What does this mean in terms of heart failure?
RV has high compliance
Right-sided heart failure typically due to an increase in afterload and is SECONDARY TO LUNG DYSFUNCTION
What are some examples of neurohormonal activation in response to decrease cardiac output?
Sympathetic activation
Renin-Angiotensin-Aldosterone activation
Anti-diuretic hormone
Why is neurohormonal control not a viable long-term solution to heart failure?
CV system is a closed loop! You can not increase preload without eventually increasing afterload, leading to decrease cardiac output.
What are some (very general) causes of heart failure?
Increased metabolic demand Increased circulating volume Increased afterload Decreased contractility Bradycardia
What would increase metabolic demand?
Fever Infection Anemia Hyperthyroidism Pregnancy
How does the heart association classify heart failure?
Class I- no limitation in physical activity
Class II- dyspnea, fatigue with moderate exertion
Class III- dyspnea with minimal exertion
Class IV- dyspnea at rest
What is the prognosis of heart disease?
5 year mortality rate is 45-60%
Class II or high is 60% mortality rate
What are the 4 goals of treating systolic heart failure?
Fix underlying causes
Manage symptoms
Modulate neurohormonal response
prolong survival
What are 5 classes of drugs used to treat heart failure with preserved ejection fraction? Why are these used?
Diuretics Renin-Angiotensin-Aldosterone Inhibitors Beta-blockers Vasodilators Positive Inotropic agents
Decrease afterload
What is an example of a positive inotrope?
Digoxin
What are Digoxin’s primary effects? Secondary effects?
Primary
- Increases contractility
- Increases Stroke Volume
- Slows Heart Rate
Secondary
- Arterial and Venous Dilation
- Normalized Arterial Baroreceptors
What is the mechanism of action for digoxin?
Inhibits the Na/K ATPase
The decreased Na gradient decreases the power for the Ca/Na exchanger, meaning that Ca stays in the cell longer
How does digoxin affect heart rate?
Increased activity of the vagal nerve leading to reduced firing at the SA node and decreased conduction at the AV node.
What is seen on an ECG of a patient taking Digoxin?
Increased PR interval
What are some negative effects of Digoxin?
- Affects all electrical systems (GI, visual, neuro, muscular)
- Increased toxicity with hypokalemia
- Multiple drug interactions
When is Digoxin used?
- Heart failure patients with LV systolic dysfunction AND atrial fibrillation
- Heart failure patients who have sinus rhythm despite maximal doses of other therapies
How does Milrinone work?
Phosphodiesterase Inhibitor
Positive inotrope that also produces vasodilation
How do dobutamine and dopamine work?
Dobutamine
-Beta1 receptor agonist, positive inotrope
Dopamine
-Simpathomimetic, positive inotrope
Why are diuretics used to treat heart failure?
- reduced preload
- reduced heart size
- reduced edema
What are three classes of diuretics? What is the main drug associated with each class?
- Loop diuretics (furosemide)
- Thiazide diuretics (chlorothiazide)
- K sparing diuretics (amiloride, triamterene)
What is the main side effect of diuretic therapy? What can be done to prevent it?
hypokalemia
prescribe K-sparing diuretics
What does angiotensin do? What does aldosterone do?
Angiotensin causes aldosterone secretion; aldosterone causes water and sodium retention
What are common ace inhibitors? Why are they prescribed for heart failure?
captopril, lisinopril, enalapril
Decrease afterload and preload
Increase survival rate
What are some potential side effects of ACE inhibitors?
Dry cough
Decreased renal function
hyperkalemia when used with aldosterone antagonists
What is an alternative for patients who can not tolerate ACE inhibitors?
Angiotensin Receptor blockers
What do aldosterone antagonists do? What are some examples?
Block aldosterone to reduce edema, decrease fibrosis
Spironolactone, eplerenone
What do beta-adrenergic receptors antagonists do?
Decrease BP, arrythmias
Increase ventricular function
Decrease mortality rate
What is important about dosing for beta-adrenergic receptor antagonists?
They can initially worsen cardiac function, so dose must start low and then increase.
What is Neprolysin?
peptidase that degrades vasoactive peptides
