Heart Failure Flashcards
Differentiate between cardiomegaly, hypertrophy, and dilation.
Cardiomegaly:
-any enlargement of the heart in either weight or size
Hypertrophy:
- increased muscle mass via length (eccentric) or width (concentric) -> increased weight
- possible increase in size (more likely with eccentric increase)
Dilation:
-enlargement of the heart chambers -> increased size and weight
**while hypertrophy technically includes both concentric (wall thickening) and eccentric (chamber enlargment), the term hypertrophy is most commonly used to refer to wall thickening and dilation to refer to chamber enlargement
What is the best measure of hypertrophy?
weight:
- isolated pressure-overload hypertrophpy will have increased wall thickness and weight
- isolated volume-overload hypertrophy will only result in increased weight
wall thickness is more practical to measure clinically but will not detect volume-overload hypertrophy
What are the types of cardiac hypertrophy?
- pressure-overload hypertrophy
- volume-overload hypertrophy
How does pressure-overload hypertrophy lead to heart failure?
Increased pressure in the chambers requires increased contractile force to expel blood
-heart adapts by concentrically adding more sarcomeres -> heart wall thickness increases
Result:
- decrease in the ventricular size due to increased wall thickness -> decreased stroke volume/cardiac output -> diastolic dysfunction
- decrease in ventricular compliance -> decreased preload/end diastolic volume -> decreased stroke volume/cardiac output -> diastolic dysfunction
What are causes of pressure overload resulting in cardiac hypertrophy?
- HTN
- aortic stenosis
- aortic regurgitation/insufficiency
- coarctation of the aorta
- mitral insufficiency (long-term)
Think high blood pressure or aorta problems
How does volume-overload hypertrophy lead to heart failure?
volume overload -> excessive preload in the chambers stretches sarcomeres too much decreasing actin/myosin interactions -> decreasing contractile strength
-heart adapts by eccentric addition of sarcomeres -> chamber dilation
-can also induce some degree of hypertrophy
Result:
- eccentric growth of sacromeres reduces contractility
- an increase in preload with reduced contractility decreases ejection fraction -> systolic dysfunction
What are causes of volume overload resulting in cardiac hypertrophy?
- valvular diseases (particularly regurgitation)
- congenital shunting defects (particularly left-to-right)
What is congestive heart failure?
-heart is unable to pump enough blood to meet demands of the body; clinically significant low cardiac output
What are the classifications of heart failure?
Functional classifications and anatomic classifications
Functional:
- systolic dysfunction
- diastolic dysfunction
Anatomic:
- left-sided
- right-sided
What differentiates systolic and diastolic dysfunction?
Systolic dysfunction:
- normal ejection fraction
- normal/reduced end diastolic volume
- reduced stroke volume/cardiac output
- associated with pressure overload/hypertrophy
Diastolic dysfunction:
- decreased ejection fraction
- increased end diastolic volume
- reduced stroke volume/cardiac output
- associated with volume overload/dilation
What are common causes of systolic and diastolic dysfunction?
Systolic dysfunction:
- ischemia (portion of ventrical become non-contractile); most common
- dilated cardiomyopathy
- valve regurgitation
Diastolic dysfunction:
- HTN/aortic stenosis; most common
- restrictive cardiomyopathy
- hypertrophic cardiomyopathy
Both:
- ischemic injury -> fibrosis/loss of function
- HTN
- valvular disease
- DM/diabetic cardiomyopathy
What is left-sided heart failure?
heart failure due to left ventricular dysfunction
What are causes of left-sided heart failure?
- ischemia
- HTN
- aortic/mitral valve dysfuction (left-sided valves)
What are clinical features of left-sided heart failure?
related to two mechanisms:
- pulmonary congestion
- insufficient organ perfusion
Pulmonary congestion:
- cough
- wheezing/rales
- dyspnea
- orthopnea
- paroxysmal nocturnal dyspnea (above occuring at night with inreased severity)
Insufficient organ perfusion (advanced stages):
- hypoxic encephalopathy -> confusion, irritability, restlessness
- prerenal azotemia
What are diagnostic features of left-sided heart failure?
Radiologic:
- Kerley B lines: fluid in interlobular spaces, extend to periphery of lung
- pulmonary congestion/edema
Histologic:
-extravasation of blood into lungs -> hemosiderin-laden macrophages, “heart failure cells“
