Pathophys of heart failure

Question 1

What is heart failure?

Answer 1

Heart failure is the inability of the heart to pump blood forward at a sufficient rate to meet the metabolic demands of the body (forward failure), or the ability to do so only if the cardiac filling pressures are abnormally high (backward failure)

Question 2

Two basic components of HF

Answer 2

Low forward flow (decreased cardiac output) and congestion (increased filling pressures) in response to low flow

Question 3

What are the causes of heart failure?

Answer 3

Failure of systole/diastole, pumps (left and/or right), dysfunctional electrical system, regurgitation or stenosis of valves or coronary arteries

Question 4

Explain systolic dysfunction

Answer 4

Decreased contraction (decreased inotropy) results in decreased stroke volume and a lower systolic blood pressure

Question 5

Hallmarks of systolic dysfunction

Answer 5

Decreased ejection fraction and ventricular enlargement (dilated cardiomyopathy)

Question 6

what does the PV loop look like in systolic HF?

Answer 6

attach image

Question 7

Primary causes of systolic HF

Answer 7

1. Direct destruction of heart muscle cells: Myocardial infarction, Viral myocarditis, Peripartum cardiomyopathy, Ideopathic dilated cardiomyopathy, Alcohol. 2. Overstressed heart muscle:Tachycardia-mediated HF, Methamphetamine abuse, Stress-provoked (tako-tsubo cardiomyopathy). 3. Volume overloaded heart muscle: Mitral regurgitation, High cardiac output

Question 8

Diastolic dysfunction

Answer 8

impaired filling (decreased lusitropy)

Question 9

Hallmarks of diastolic dysfunction

Answer 9

Normal ejection fraction and ventricular wall thickening (left ventricular hypertrophy) decreases stroke volume

Question 10

what does the PV loop look like in diastolic HF?

Answer 10

see image

Question 11

Primary causes of diastolic HF

Answer 11

1. High afterload/pressure overload: Hypertension (long-standing), Aortic stenosis, Dialysis (inadequate volume removal)
2. Myocardial thickening / fibrosis: Hypertrophic cardiomyopathy, Primary restrictive cardiomopathy. 3. External compression: Pericardial fibrosis / constrictive pericarditis, Pericardial effusion

Question 12

Right sided heart failure can result in what?

Answer 12

decreased circulating blood flow (forward RV HF) or increased venous pressures (backward RV HF)

Question 13

primary causes of right sided HF

Answer 13

1. Left heart failure, 2. Lung disease / pulmonary HTN / RV pressure overload: Called “cor pulmonale” when primary lung dz causes HF, COPD, primary pulmonary hypertension, sleep apnea
2. RV Volume overload: Shunt (interatrial septal defect),Tricuspid regurgitation. 4. Damage to the RV myocardium: Isolated RV infarct, Myocarditis

Question 14

Describe Frank-Starling compensation in HF

Answer 14

Increased pre-load (end diastolic pressure) helps preserve stroke volume

Question 15

How does Renin-Angiotensin activation affect HF?

Answer 15

Vasoconstriction and increased sodium retention inccreases blood volume which compensates for decreased LV filling short term. Long term, it actually promotes HF by increasing cardiac workload, ventricular hypertrophy/dilation, myocardial damage.

Question 16

How does adrenergic activation affect HF?

Answer 16

vasoconstriction, tachycardia and inotropic augmentation compensate in the short term. Long term, it actually promotes HF by increasing cardiac workload, ventricular hypertrophy, etc.

Question 17

What role does cardiac remodeling play in HF?

Answer 17

compensatory mechanism that cuases hypertrophy, hyperplasia, necrosis or fibrosis. This results in decreased contractile force, decreased dynamic function and increased diastolic stiffness.