Heart Failure I: Pathophysiology

Question 1

What’s the prevalence of heart failure in the US? What’s the incidence (how many new ones in a year)?

Answer 1

prevalence: 6 million in US have HF
incidence: 550,000 new cases each year

Question 2

What are the direct medical costs from HF?

Answer 2

~40 billion

12 million clinic visits
1,200,000 hospital visits
#1 in Medicare billing

Question 3

How many people die from it? (directly/ indirectly)

Answer 3

57,000 per year = primary HF

281,000 per year = any mention of HF

Question 4

Give a definition of heart failure…. (include two types of failure)

Answer 4

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

**Disclaimer: its a blanket syndrome that covers a lot of stuff

Question 5

T/F: Heart failure is either predominantly by poor forward flow or backward build up of pressure?

Answer 5

False: both are almost always present

-decreased flow (cardiac output) typically results in congestion (increased filling pressures)

Question 6

List as many possible dysfunctions causing HF that you can

Answer 6

• failure to contract (systole) or relax (diastole)
• left side, right side, or both dysfunction
• slow, fast, or asynchronous electrical conduction
• regurgitation (backflow) or stenosis (resistance)
• coronary artery problems
• pericardial issues

Question 7

What three key mediators affect blood flow?

Answer 7

Inotropy
Preload
Afterload

Question 8

According to the Frank-Starling Law, what increases stroke volume?

Answer 8

Diastolic filling

Question 9

How does inotropy affect preload?

Answer 9

Trick question: it doesn’t
-it increases stroke volume by squeezing harder (contractility)

-is effective at any level of end-diastolic preload

Question 10

How does inotropy work?

Answer 10

adrenergic/ catecholaminergic stimulation increases the amount of Calcium making a stronger contraction

Question 11

If I have fibrosis, or hypertrophy, or ischemia in my heart, what will be most compromised?

Answer 11

Compliance

=inability to relax and decreased diastolic filling at a given pressure

Question 12

On a PV loop diagram, how will increased preload or compliance manifest? (basic directional shift)

Answer 12

Extend horizontally to the right (increased diastolic filling)
=>increases SV

Question 13

On a PV loop diagram, how will increased inotropy manifest? (basic directional shift)

Answer 13

extends vertically AND wider (pump out more blood)

=>increases stroke volume

Question 14

On a PV loop diagram, how will increased after load manifest? (basic directional shift)

Answer 14

extends vertically but thinner (higher pressure- less volume pumped out)

=>decreases stroke volume

Question 15

Whats the difference between systolic and diastolic dysfunction?

Answer 15

Systolic = decreased squeeze
diastolic = decreased filling

Question 16

What are the primary causes of systolic HF?

Answer 16

Direct destruction of heart muscle (ie. MI)
Overstressed heart (ie. tacky, meth)
Volume overloaded heart muscle (ie. regurg)

Question 17

What happens with decreased lusitropy?

Answer 17

Lusitropy = ability to relax

-you get impaired filling

Question 18

Whats the difference between HFpEF and HFrEF? Which one is hallmark of systolic HF?

Answer 18

HFpEF (preserved ejection fraction)

HFrEF (reduced ejection fraction)
=Seen in systolic HF

Question 19

How does the PV loop change with diastolic HF (stiffening)?

Answer 19

The bottom line shifts vertically of the x axis

-because you need to increase the pressure (y axis) to achieve same volume

Question 20

How would left ventricular hypertrophy affect your hearts activities?

Answer 20

• decreased filling

- preserved systolic function

Question 21

How does external compression (pericardial fibrosis, pericardial effusion) affect the heart?

Answer 21

Cause diastolic HF

Question 22

Why does a high afterload (hypertension, aortic stenosis, dialysis) cause diastolic HF?

Answer 22

***While this might immediately affect systolic function, over time this leads to hypertrophic cardiomyopathy which decreases ability to fill left ventricle

Question 23

Whats the normal pulmonary pressure on the right heart?

Answer 23

22/ 10 mmHg

Question 24

What are the effects of right sided heart failure?

Answer 24

decreased circulating blood

increased venous pressure

Question 25

What are the causes of right sided heart failure?

Answer 25

• left heart failure
• lung disease
• RV volume overload (tricuspid regurg., shunt)
• damage to RV (infarction, myocarditis)

Question 26

How does the body usually respond to decreased CO?

Answer 26

-Renin-angiotensin-aldosterone (RAAS) activation
>increased Na retention&raquo_space; increase fluid
>vasoconstriction

-Autonomic nervous system/ adrenergic activation
>Increased HR
>vasoconstriction

Question 27

Why is the neurohormonal (adrenergic/RAAS) response considered “short term gain for long term loss”?

Answer 27

You increase fluid filling pressures which temporarily helps but stresses the heart even more

(Compensation via Frank-Starling = increasing end-diastolic pressure to maintain SV)

Question 28

Okay, so besides compensating for low CO by increasing HR and fluid retention, what else can you do?

Answer 28

Increase contractility

-hypertrophy