7.2 Cardiac Output, Heart Failure Flashcards
What is LVEF? How measured?
Left ventricular ejection fraction
% of volume of blood pumped out with each contraction
= (Stroke volume/ End diastolic volume [full]) x 100
Gives a %… Make sit easy to compare
What is a normal LVEF? Heart failure?
Normal- 55-85%
Heart Failure- <40%
What is the definition of heart failure?
Failure of ventricle to fill or pump enough blood to the systemic circulation
What are some causes of systolic heart failure?
weakened contraction of ventricle due to ischemia, valvular disease, hypertension, cardiomyopathy
What are some causes of diastolic heart failure?
ventricle unable to fill due to hypertrophy, fibrosis, amyloid deposition or pericarditis
What is associated with CHF?
Fluid retention
What are the pathological changes in HF?
Ventricular Remodeling:
Hypertrophy – increased cell size and overall mass of heart, especially left ventricle due to increased workload
increases oxygen demands without increase in blood supply can lead to dysfunction
Dilation – inner chamber enlarges,
Fibrosis – deposition of collagen
Contractility declines due to ischemia, work overload, ventricular remodeling
Ventricular filling declines due to valvular abnormalities or lack of venous return
Fluid Overload-
Blood Volume signaling cascades activated when tissue perfusion is inadequate, can worsen fluid retention, worsen heart failure
How does MI lead to HF?
low levels of oxygen and nutrients
Infarction: death of tissue
coronary artery disease, atherosclerosis in coronary arteries
low levels of oxygen and nutrients due to lack of blood flow to the ventricles –> ischemia –> myocardial infarction
if survived, ventricular contraction is compromised
How does chronic hypertension lead to HF?
high blood pressure in aorta
increases resistance and workload of left ventricle
hypertrophy of left ventricle
coronary blood supply becomes insufficient –> ischemia
left ventricle wall thickens, filling space decreases –> decreased contraction
How does pulmonary disease lead to HF?
multiple causes, includes chronic bronchitis and emphysema which lead to reduced airflow and reduced gas exchange in the lungs
lung disease leads to hypoxia
hypoxia stimulates pulmonary artery blood pressure – pulmonary hypertension
high blood pressure in pulmonary circuit increases resistance against right ventricle
right ventricular hypertrophy
coronary blood supply becomes insufficient–> ischemia
cor pulmonale: right ventricular failure due to lung disease
congestion of systemic and portal venous systems
How does aortic stenosis lead to HF?
increased aortic resistance
increased ventricular pressure and volume overload
leads to left ventricular hypertrophy
coronary blood supply becomes insufficient –> ischemia
ventricle wall thickens, filling space decreases –> decreased contraction
How does mitral valve regurgitation lead to HF?
Weakening of valves or paillary muscles
Blood can back up into atria–> fluid backs up in lung capillaries
What is the molecular response to heart failure?
Response to cardiovascular damage: endothelin (Heart, vessels) TNF-alpha (Heart) Response to inadequate tissue perfusion Norepinephrine (Autonomic) RAAS Pathway (Kidneys) ADH (Pituitary) ANP/BNP (Heart)
What is the endothelin response to HF?
peptide secreted by heart and blood vessel endothelium during myocardial infarction, heart failure
vasoconstriction of arteries, increased resistance on left ventricle
increased workload, strains left ventricle
fibrotic changes in myocardium (part of remodeling)
What is the TNF response to HF?
Tumor Necrosis Factor-Alpha (TNF-alpha): inflammatory cytokine increases in heart, blood during heart failure
stimulates hypertrophy, fibrotic changes
apoptosis of myocardium
decreases contractility (blocks inotropic effects)
