12/9/2014 Medical Physiology CC: Heart Failure Harold Smulyan Flashcards Preview

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Flashcards in 12/9/2014 Medical Physiology CC: Heart Failure Harold Smulyan Deck (34):
1

What is the definition of heart failure?

Inability of the heart to meet the metabolic needs of the body at normal filling pressures

2

What is important to distinguish HF from?

Cardiac dysfunction with successful adaptation

3

HF happens when...

...adaptation fails and becomes part of the problem

4

What is the clinical diagnosis of HF?

*no single finding

*a complex of findings

5

What are the 2 different diagnosis of which HF becomes the final common pathway?

1. Decreased circulatory supply to the body

2. Increased circulatory demand from the body

6

What are some of the conditions that can decrease circulatory supply to the body?

- coronary heart disease
* MI
* ischemic cardiomyopathy

- valvular heart disease
- cardiomyopathy

7

What are some of the conditions that can increase circulatory demand from the body?

- hypertension
- thyrotoxicosis
- anemia
- A-V fistula

8

Adaptive mechanisms

Compensations that maintain pump function in the presence of heart disease or increased demand

9

What are the 3 main adaptive mechanisms of HF?

1. Frank – Starling
(short term)

2. Neuro-hormonal (intermediate)
a. Renal

3. Hypertrophy
(long term)

10

In a ventricular EDV vs. ventricular performance diagram (F-S mechanism):

1. Normal curve shows improved ventricular performance when the end-diastolic volume is increased (increased pre-load or venous return)

2. Normal curve moves upward and to the left with exercise or increased sympathetic stimulation.

3. Abnormal curve (in green) moves down and to the right with impaired ventricular performance.

11

In a LV filling pressure (left atrial pressure in diastole) vs. LV stroke work diagram:

1. groups above and to the left of normal show the effects of exercise and/or sympathetic stimulation

2. groups down and to the right of normal show progressive reduction of the change in stroke work with increasing LV filling pressure

3. with increasingly severe LV dysfunction the LV filling pressure reaches 25mmHg, where the oncotic pressure of the plasma is exceeded and fluid crosses the alveolar membrane and enters the pulmonary alveoli

12

The neurohumoral adaptive mechanism of HF is related to:

Sympathetic stimulation -increased plasma NE

*redistribution of CO
*maintains flow to the brain and heart at expense of skin, skeletal muscle, gut and kidneys

13

What are the adaptive mechanisms of HF in the renal system?

Stimuli:

- decrease GFR
- decrease RBF
- increase aldosterone

Response:

- increase sodium and water retention
- increase plasma volume
- increase venous return
- increase venous pressure

14

Beta 1 receptor density is ___ and Beta 2 receptor density is ___ by HF

reduced; not reduced

15

LV contractility (dp/dt) ___ with addition of intracoronary dobutamine in patients with HF

decreases

16

What is the common theme between the stuff listed below and HF?

PNE = Plasma norepinephrine
PRA = Plasma renin activity
AVP = Arginine vasopressin
ANP = Atrial natriuretic peptide
ENDO = Endothelin

They are all increased with HF

17

1. If abnormality can be corrected, hypertrophy will ___

2. If abnormality is not corrected, myocardial dysfunction will ___

1. regress

2. worsen and become permanent

18

Ejection Fraction equals

(EDV-ESV)/EDVx100

19

What are two responses to hemodynamic overload?

Pressure overload

Volume overload

20

How does hypertrophy maintain pump function (CO)?

By keeping wall stress near normal

21

Pressure overload ___ systolic wall stress

increases

22

Volume overload ___ diastolic wall stress

increases

23

Both pressure and volume overloads lead to ___

ventricular remodeling

24

In pressure overload, sarcomeres arranged in ___

parallel

25

In volume overload, sarcomeres arrange in ___

series

26

Pressure overload leads to ___

concentric hypertrophy
(thicker LV)

27

Volume overload leads to ___

eccentric hypertrophy
(greater LV volume)

28

h/R: ratio of wall thickness to chamber radius –> ___ in pressure
overload

greater

29

Adaptation disadvantage of F-S response

High LVEDP -pulmonary edema

30

Adaptation disadvantages of neuro-humoral response

1. increased myocardial O2 consumption

2. arrhythmias

3. diminished response to sympathetic stimulation

4. blunted baroreceptor function

5. increased systemic vascular resistance

31

Adaptation disadvantages of renal response

1. peripheral/organ edema

2. decreased renal function

32

Adaptation disadvantages of myocardial hypertrophy response

1. decreased contractility

2. necrosis and apoptosis

3. decreased coronary reserve

4. changes in matrix (diastole)

33

What are some of the main failure maladaptations?

- worsening LV function
- fluid retention (pulmonary edema)
- excessive increase in vascular resistance
- renal failure

34

Therapies range:

- addressing underlying cause

- medications such as diuretics, vasodilators and beta blockers

- LVAD

- transplantation

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