Part 25: Heart Failure Flashcards
at the most fundamental level, what causes heart failure?
progressive damage to the heart that results in reduced cardiac output
reduced CO that is seen in heart failure can present as ____
weakness, fatigue
why does reduced CO in heart failure present as weakness and fatigue?
the body is getting less oxygenated blood to the tissues
the complexity of heart failure comes from what happens when the body tries to ____
compensate and correct for the decreased CO
define cardiac output (CO)
amount of blood pumped per heart beat (stroke volume) x # of heart beats per minute (HR)
to compensate for decreased CO, the ____ nervous system is activated
sympathetic
how does sypathetic activation act to compensate for the decreased CO of heart failure?
NT stimulates B1 receptors in the heart, causing increased heart rate and contractility and increasing renin secretion to increase water retention
why cant we rely solely on our endogenous compensatory mechanisms for treatment of heart failure?
can only be used short term, for example during exercise and heart failure needs chronic attention. If the compensatory mechanisms tried to do this alone, it would lead to damage (remodelling) and the fluid retention may cause edema and difficulty breathing
what are the 3 primary management strategies for managing heart failure?
- reduce symptoms
- decrease progressive damage and remodelling of the heart
- if cardiac output is significantly impaired, adding agents to increase CO
what are the main underlying causes of heart failure?
hypertension and coronary artery disease
in what part of the heart is heart failure most common and why?
the left ventricle bc it does the most work moving blood out into circulation
what is congestive heart failure?
umbrella term for any type of heart failure that has a fluid or congestion component
what does the “congestive” part of congestive heart failure mean?
refers to the accumulation of fluid and edema caused by the failing heart
left sided heart failure means
left ventricular failure to fill and pump blood into circulation
left sided hart failure may cause accumulation of fluid in the ____, which is called ____ and is due to ____
lungs; pulmonary edema; blood backing up i the lungs
right sided heart failure means
right ventricular failure to fill and pump blood to the lungs
right sided HF may cause fluid accumulation in the ___, called ___, due to ___
peripheries; peripheral edema; blood backing up into the veins
t/f failure of one ventricle will often progress to the failure of both
t
is the pumping action of the heart is reduced, this is called ___ heart failure
systolic
the capacity of the heart to pump blood out of the ventricles is measured by the ____ (the % of the blood pushed out of the chamber during contraction)
ejiection fraction
normally, ____% of the blood in the ventricle is pushed out during systole
50-70%
in systolic failure, the contraction of the ventricles pushes ___(more/less) blood out of the chamber, leaving ____ (more/less) behind
less; more
in systolic failure, the ejection fraction / proportion of blood pumped out with each contraction is ____ (increased/decreased)
decreased
a diagnosis of HF is usually made when ejection fraction falls below ___%, but patients in the ____% range can be considered borderline and may experience symptoms of HF with exertion
40; 40-50
systolic HF is more commonly called ___
HF-rEF: heart failure with reduced ejection fraction
____ HF occurs when stiffening of the ventricular walls prevents the chambers from filling to their normal capacity
diastolic
in what type of HF is there less blood in the chamber before contraction, so less blood is pumped to circulation (reduced CO)
diastolic HF
is the EF always reduced in diastolic HF?
no
what is the other name for diastolic HF?
HF pEF: HF with preserved ejection fraction
HF pEF can occur bc despite the volume being reduced, the ____ remains within the normal range
proportion
in HF pEF, why is increasing the contractility of the heart is less likely to improve CO?
the contracting of the heart isnt as much of an issue in this type of HF
in HF pef, reduced ____impairs the filling of the ventricles
stretch of the cardiac muscle
the _____ uses a roman numeral system to characterize HF from class I-IV
New York Heart Association
the New York Heart Association bases the classification of heart failure based on ____
the activity level that causes symptoms like dyspnea, heart palpitations, fatigue etc.
what are the 4 classifications of the New York Heart Association?
I: no symptoms with regular activity, symptoms may develop with high activity
ii: symptoms with regular activity
iii: symptoms with less than regular activity
iv: symptoms at rest or minimal activity
what type of classification system is used by the American College of Cardiology?
stages A to D
how does the ACC group HF into the A to D stages?
uses a combination of risk factors, structural information about the heart and symptoms
what structural features would be examined for the ACC classification of HF?
ischemic damage from a previous heart attack, cardiac remodeling such as hypertrophy (enlarged heart), abnormal electrial activity (electrocardiography)
what are the 2 pre-HF stages from the ACC classification?
A and B
what is the benefit of early detection of class A and B HF?
early treatment can delay the progression of HF and significantly impact the QOL
describe the A-D classifications of HF from ACC
A: pre-HF, no symptoms or structural features, but they have risk factors
B: pre-HF, structural features (hypertrophy, past MI), but no symptoms
C: structural & symptomatic HF
D: advanced symptomatic HF despite pharm interventions
which classes of antihypertensives are best for the fluid retention and edema associated with HF?
diuretics, ACE inhibitors, ARBs
give an example of a ARB + neprilysin inhibitor (ANRI) drug used for HF
valsartan/sacubitril
give 2 examples of positive ionotropic drugs
dobutamine and digoxin
for pts requiring extensive diuresis and excretion of large volumes of fluid, what is the best type of diuretic to use?
a loop diuretic like furosemide (the HCTZ loop diuretic may cause hypokalemia, so be careful)
in some cases _____ can be added with furosemide to retain K and aide in diuresis by blocking the actions of aldoesterone in the collecting duct
spironolactone
____ and ____ type drugs are also commonly used in HF as they have multiple beneficial actions reducing fluid retention and lowering BP
ACE inhibitors and angiotensin receptor blockers
t/f the ARB/ANRI combination have been shown to have benefit in HF in comparison to an ACE inhibitor or ARB alone
t
____ are endogenous hormones that counter balance the actions of the renin-angiotensin system
natriuretic peptides
the natriuretic peptides promote ____ (vasodilation/constriction) and _____ (fluid retention/diuresis)
vasodilation; diureses
what is neprilysin?
endogenous enzyme primarily responsible for the breakdown of natriuretic peptides, bradykinin and angiotensin
why is it important to add an ARB with an ANRI?
bc blocking the natriuretic peptide (by the ANRI) can also increase levels of angiotensin 2, which could cause vasoconstriction, so we add the ARB to inhibit the A2 so that we have a vasodilatlry effect
t/f the ARB/ANRI combo is not used as much bc its newer and most patients are trialed on older ones with more info
t
HF patient with additional CVD like angina may benefit from the addition of _____ class drug
Ca channel blocker
what class of drug is typically used for the chronic treatment of HF?
a sympatholytic agent like careviol that acts on beta and alpha
beta-blockers can slow the progression of HF and reduce cardiac ___-
remodelling
in what HF scenarios may the use of B blockers not be appropriate?
can further educe CO so not good for pts with an acute exacerbation of HF or those with very low CO
when a patient has very low CO, what class of drugs is a good choice for managing heart failure?
positive inotropic drugs
what is dobutamine?
a + inotropic selective B1 agonist
what is the effect of dobutamine on intracellular Ca, contraction, heart rate and CO
increase all of them
why is dobutamine not used long term?
activates B1, which results in long term remodelling of the heart and progression of heart failure
what are some acute situations where dobutamine may be used?
typically in hospital; surgery, cardiogenic shock, cardiac arrest
very low CO may be called ___
cardiac decomposition
what is an ADR of dobutamine?
arrhythmias
t/f digoxin is a + inotropic drug that can be used chronically for HF to increase CO
t
in what stage of HF is digoxin used?
advanced
digoxin belongs to a group of compounds called ____
cardiac glycosides
what is the only cardiac glycoside that is used clinically?
digoxin
digoxin and related compounds were originally isolated from plants of the ____ genus
Digitalis
why are digitalis natural remedies not commonly used anymore?
high toxicity and narrow therapeutic range
digoxin ____(increase/decrease) cardiac contractility and ____ (slows/raises) hear rate
increases; slows
digoxin is used in what stage of HF?
advanved stages that have not been responsive to other thinsg
the digitalis plant that digoxin comes from is also called ____
fox glove
what is an ADR of digoxin?
arrrhythmias
what is the MOA of digoxin?
inhibits the Na/K pump in cardiac muscle cells
in the ventricular myocytes, digoxin blocks the Na/K pump causes an accumulation of ____ in the cell which is exchanged for ____ by the ____ exchanger
Na; Ca; NCX
bc digoxin blocks the Na/K pump it makes it ____ (harder/easier) to remove the Na from the cell after an action potential to return to resting state
harder
how can digoxin result in larger ventricylar contraction?
bc the Na/K pump is blocked, the NCX gets used more, so more Ca comes in and gets put in SR storage that will cause a greater release of Ca the next time = greater contraction
how can digoxin cause arrhythmias at very high doses?
so much Na and Ca accumulates in the cell that the resting potential is depolarized in comparison to the control and the SR is so full of Ca that it spontaneously spits ou t Ca causing the uncoordinated contractions that cause arrhythmias
the SA node sets the HR by spontaneously firing APs and sending them to the ____ for propogation to the ventricles to cause contraction
AV node
the rate of SA node firing and AV conduction of the APs is modulated by the ____ nervous system
autonomic
digoxin reduced HR by ___
slowing the propogation of AP in cardiac tissues
the effect of digoxin slowing heart rate are also called ___
parasympathomimetic or vagomimetic
digoxin slows HR by increasing Ca, which prolngs the ____ of electrical conduction in the heart
refractory period
