Heart Failure pathophysiology Flashcards Preview

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Flashcards in Heart Failure pathophysiology Deck (46):
1

What is the overall cost of heart failure in the US?


• Over 40 billion dollars. Crazy
• 6 million people in US population
• 12 million clinic visits
• 550,000 every year new incidence

2

In whom will you expect to see heart failure?

• Older patients
• Median age is 75 years
• Thus, since population is aging, problem is more common
• Also, more people surviving initial cardiac disease

3

1/2 of patients with symptomatic HF will be dead in how many years?

• 5 years

4

What is the definition of heart failure?






• Inability of heart to pump blood forward at a sufficient rate to meet the metabolic demands of the body
○ "forward failure"
• OR ability to do so only if cardiac filling pressures are abnormally high
○ "backward failure"

5

What are the three entities that play into stroke volume?

• Contractility
• Preload
• Afterload

6

What are the two different components of the HF syndrome?

• Poor forward blood flow
○ Low flow and reduced CO
• Backward buildup of pressure
○ Congestion, increased filling pressures
○ Typically a response to low flow

7

Is Heart Failure a definite, defined disease?

• Nope. It's a 'end game' that comes from many different problems

8

What is meant by "forward failure"?

• Inability of heart to pump blood forward at a sufficient rate to meet the metabolic demands of the body

9

What is meant by "backward failure"?

• OR ability to do so only if cardiac filling pressures are abnormally high

10

What is the effect of preload on the force-tension relationship?




• Increased preload, according ot frank-starling principle, will increase cardiac output
• Increase ventricular EDP (end diastolic pressure), stroke volume increases (to a point)
• This is true for the same inotropic state

11

Draw the three following pressure-volume loops

• Increased preload, 3 beats
○ Increased EDV, but constant ESV, meaning more sroke volume
• Increased inotropy, 2 beats
○ ESPVR changes slope, more steep. Also changes y intercept (higher)
○ ESV decreases, EDV stays the same
○ Increased SV
• Increased afterload, 3 beats
○ ESPVR is a line that governs the verticle border of the loop
○ EDV does not change, but ESV does change (heart isn't getting rid of more blood)
○ Stroke volume decreases

12

What does increased inotropy do?

• Increases stroke voume for the same level of preload (shifts frank-starling curve UP)

13

What are the determinants of inotropy?

• Determined by catecholaminergic/adrenergic stimulation and calcium

14

What is inotropy?

• Contractility. Increased inotropy means increased contractility
• Same preload, but greater force of contraction
• Determined by catecholaminergic/adrenergic stimulation
• Calcium

15

What are the four major divisions of the heart failure syndrome?





• Systolic vs. diastolic
• Left vs. right
• Acute vs chronic
• Symptomatic vs. asymptomatic vs. at risk

16

What are some examples of volume overloaded heart muscle causing systolic HF?

• Volume overloaded heart muscle
○ Mitral regurgitation
○ High cardiac output
§ Shunting of blood/holes in heart
§ Wet beriberi (thiamine B1 deficiency)

17

What are some examples of overstressed heart muscle causing systolic HF?

• Overstressed heart muscle
○ Tachycardia-mediated HF
○ Methamphetamine abuse
○ Catecholamine mediated
§ Takotsubo cardiomyopathy

18

What are some examples of direct destruction of heart muscle cells?

• Direct destruction of heart muscle cells
○ Myocardial infarction
○ Viral myocarditis
○ Peripartum cardiomyopathy
○ Ideopathic dilated cardiomyopathy
○ Alcohol abuse

19

What are the three (general) primary causes of systolic heart failure?

• Direct destruction of heart muscle cells
• Overstressed heart muscle
• Volume overloaded heart muscle

20

Draw the pressure-volume loop for normal vs. Systolic HF

• Shows reduced inotropy
○ Lower pressures achieved, so lower on y axis
• Decreased stroke volume
○ Slightly increased EDV and larger increased ESV

21

What are the hallmarks of systolic heart failure?

• Decreased ejection fraction
• HFrEF
○ Heart failure with reduced ejection fraction
• LVSD
○ Left ventricular systolic dysfunction
• Ventricular enlargement
○ Dilated cardiomyopathy = DCM

22

A decrease in what is the main problem in diastolic heart failure?




• Decrease in filling
• Decreased lusitropy (unable to relax)
• Decrease in filling time (high heart rate)

23

Draw the PV loop diagram of diastolic HF

• Increased stiffness requires increased pressure to achieve the same EDV
• The bottom curve/boundary shifts up
• Lowers stroke volume
• The upper curve/line stays the same and the ESV stays the same

24

What are the examples of external compression causing diastolic HF?

• Pericaridal fibrosis/constrictive pericarditis
• Pericardial effusion

25

What are the examples of myocardial thickening/fibrosis causing diastolic HF?

• Hypertrophic cardiomyopathy
• Primary restrictive cardiomyopathy

26

What are the examples of high afterload causing diastolic HF?

• Hypertension (chronic)
• Aortic stenosis
• Dialysis (inappropriate volume removal)

27

What are the three (general) causes of diastolic heart failure?

• High afterload/pressure overload
• Myocardial thickening/fibrosis
• External compression

28

What are the hallmarks of diastolic heart failure?

• Normal ejection fraction
○ HF with preserved ejection fraction = HFpEF
○ Preserved systolic function = PSF
• Ventricular wall thickening
○ Left ventricular hypertrophy
§ LVH (general descriptive term)
○ Hypertrophic cardiomyopathy
§ HCM (specific genetic disease)

29

What is the right heart supposed to do?





• Pump blood into the lungs
• It's working against a much lower pressure system, so it's walls are much thinner than the left walls
• Normal pulmonary pressure if 22/10 mmHG (right ventricle)

30

What are the direct examples of Damage to RV myocardium

• Isolated RV infarct
• myocarditis

31

What are the direct examples of RV volume overload

• Shunt (interatrial septal defect)
• Tricuspid regurgitation

32

What are the direct examples of Lung disease/pulmonary HTN

• Called "cor pulmonale" when primary lung disease causes HF
• COPD,
• primary pulmonary hypertension
• Sleep apnea

33

What are the direct examples of Left heart failure?

• Backward HF from LV dysfunction stresses the right side by increasing pulmonary venous pressures
• The most common cause of RHF is LHF

34

What are the 4 (general) causes of right-sided heart failure?

• Left heart failure
• Lung disease/pulmonary HTN
○ Results in RV pressure overload
• RV volume overload
• Damage to RV myocardium

35

What is meant by backward RV HF?

• Increasing venous pressures

36

What is meant by forward RV HF?

• Decreasing circulating blood flow

37

What is the Fontan procedure and what does it illustrate?

• It is a single ventricle physiology procedure
• In gongenital heart disease where there is effectively only one ventricle, it is possible to hook the SVC/IVC directly to pulmoary artery
• As long as pulmonary pressures are low (normalish) blood flow is maintained
• This illustrates how dang low pulmonary pressures are

38

What is normal pulmonary pressure that the RV has to push against?

• Normal pulmonary pressure if 22/10 mmHG (right ventricle)
• Results in a much thinner walled structure

39

What is the underlying "problem" in all heart failure?



• Insufficient blood flow
• The heart must have a solution in the form of compensatory mechanisms
○ Neurohormonal activation
○ Framk-starling curves
§ Increase preload to increase stroke volume
○ Ventricular hypertrophy and dilation

40

How does the "normal response" to decreased CO incorporate the baroreceptor reflex?

• Carotid sinus/aortic baroreceptors sense lower pressure
• Autonomic nervous system activated
○ ADRENERGIC activation
• Increases HR and increases vasoconstriction

41

How does the "normal response" to decreased CO incorporate the kidneys?

• Juxtaglomerular apparatus in kidney senses lower flow
• Renin-angiotensin-aldosterone activation
○ RAAS
• Increased na and thus water retention to increase blood volume and rectivy the decreased LV filling
• Also leads to vasoconstriction

42

Why does neurohormonal activation lead to problems in HF?

• RAAS activation and adrenergic activation
• In systolic HF or diastolic HF
○ Decreased LV squeeze
○ Incerased stiffness
• The increase in water retention and inrease in vasoconstriction increase blood pressure to get more blood into the ventricle (which is stiff)
• The increased pressures aren't going to help in the long run, and it makes the muscle even stiffer

43

Why the congestion in CHF?



• Low cardiac output results in fluid retention to maintain SV/CO by increasing pressure of filling
• But increased pressure means decreased overall flow and increased filtration and edema…CHF

44

What does adverse myocardial remodeling look like in particular?

• Ventricular hypertorphy
• Ventricular dilation
• Myocardial damage/apoptosis
• Myocardial fibrosis

45

What does adrenergic activation contribue in ventricular remodeling?

• Vasoconstriction (increased pressure)
• Tachycardia (to incrase CO but it sacrifices SV…)
• Inotropic augmentation

46

What are the three general ways that chronic neurohormonal activation begets worsening heart failure?

• Adrenergic activation
• RAAS activation
• Long term increase in cardiac workload and increased metabolic demands promotes adverse myocardial remodeling