Lecture 26 Flashcards
What constitutes heart failure?
- Failure of heart to pump adequate blood to satisfy body’s needs
- Certain conditions or diseases lead to a decrease in CO
- Can involve the right ventricle, left ventricle or both
Disorder of coronary arteries, hypertension, cardiomyopathy, heart valve disorder, abnormal heart rhythm can lead to a decrease in _____ _____.
CO
T or F? With time, failure of one ventricle leads to failure of the other.
True
What are characteristics of systolic heart failure?
- Dysfunctional mechanical pumping
- Most often caused by coronary artery disease which reduces coronary blood flow to heart leading to hypoxia and impaired contractility.
- Reduced cardiac output and ejection fraction
Dysfunctional mechanical pumping in systolic heart failure leads to decreased _________.
Contractility
Systolic heart failure, often caused by coronary artery disease, reduces coronary blood flow to heart leading to hypoxia and impaired contractility. What events leads to ↓CO and ↓EF?
Impaired contractility→ ↓SV → ↑ESV → ↑EDV/preload → with a chronic increase in EDV, the ventricle remodels by dilating (enlargement) → ↓force development→ ↓SV → reduced cardiac output and ejection fraction.
What is a good indication of systolic heart failure?
Reduced cardiac output and ejection fraction are good indication.
What are characteristics of diastolic heart failure?
- Inadequate relaxation and reduced filling
- Most often caused by hypertension → ↑ afterload → stimulation of ventricular hypertrophy → ↑ stiffness (↓ compliance) → ↓filling → ↓EDV → ↓SV → ↓CO
- Reduced cardiac output, but ejection fraction may be near normal; thus reduced EF is useful only as an indicator of systolic failure
T or F? Pressure overload leads to dilation of chambers (enlargement; cardiomegaly); volume overload (i.e. increased afterload) leads to hypertrophy of chambers (thicker walls).
False, the opposite is true.
Volume → enlargement
Pressure → hypertrophy of chambers
How does the body compensate for heart failure?
By the activation of SNS and RAAS. (however, it causes progressive weakening of heart)
Long-term activation of the SNS and RAAS contributes to weakening of the heart is because they ultimately increase the ______ of the heart, which puts a strain on the heart muscle.
work (The SNS and RAAS increase the oxygen demand of the heart muscle, it has to work harder to deliver that oxygen or the muscle will become hypoxic. Hypoxia will cause weakening. It is a vicious cycle.)
What are the effects of the SNS?
- Tachycardia (increases O2 consumption)
- Increases contractility (increases O2 consumption)
- Venoconstriction (increases preload, which increases O2 consumption)
- Vasoconstriction (increases afterload, which increases O2 consumption) )
- Chronic norepinephrine exposure is toxic to myocardial cells (causes apoptosis)
- Increases risk of arrhythmias which can decrease CO
What are the effects of RAAS: Ang II?
- Vasocontriction (increases afterload)
- Stimulates renal sodium and water reabsorption (increases blood volume and preload)
- Stimulates SNS
- Stimulates ventricular remodeling (which causes dysfunction)
What are the effects of RAAS: Aldosterone?
- Stimulates renal sodium and water reabsorption (increases blood volume and preload)
- Stimulates interstitial cardiac fibrosis (causing stiffness and dysfunction)
- Increases risk for arrhythmias
What other hormones contributes to heart failure?
Norepinephrine, Angiotensin II, Aldosterone, ADH
