Pathophysiology of Heart failure

Question 1

what is the Frank Starling Law of the heart

Answer 1

1. relationship between EDV, contraction strength and SV
2. intrinsic mechanism:
   - varying degree of stretching of myocardium by EDV
   - as EDV increases: myocardium is increasingly stretched, and contracts more forcefully
3. as ventricles fill, the myocardium stretches
   - increases the number of interactions between actin and myosin
4. allows more force to develop
5. explains how the heart can adjust to rise in TPR

Question 2

what can also affect the functioning of a failing heart

Answer 2

changes in afterload

Question 3

what does right heart failure cause

Answer 3

congestion of peripheral tissues
- this leads to dependent edema and ascites and liver congestion
- this leads to GIT congestion

Question 4

what does left heart failure cause

Answer 4

1. decreased cardiac output
2. pulmonary congestion
   - this leads to impaired gas exchange and pulmonary oedema

Question 5

what are the signs and symptoms of left sided failure

Answer 5

1. confusion
2. pulmonary congestion
   - cough
   - wheezing
3. tachycardia
4. restlessness
5. paroxysmal nocturnal dyspnea

Question 6

what are the signs and symptoms of right sided heart failure

Answer 6

1. may be secondary to chronic pulmonary problems
2. weight gain
3. anorexia and complaints of GI distress
4. increased peripheral venous pressure
5. ascites
6. enlarged liver and spleen
7. swollen legs
8. raised JVp

Question 7

why does oedema occur in patients with heart failure

Answer 7

heart failure leads to the accumulation of blood
- this causes pressure to accumulate and venous congestion occurs

Question 8

what happens in an arterial end net filtration pressure of +10mm Hg

Answer 8

filtration
- fluid exits capillary since capillary hydrostatic pressure is greater than blood colloidal osmotic pressure

Question 9

what occurs in a mid capillary net filtration pressure of 0

Answer 9

no net movement of fluid since capillary hydrostatic pressure is equal to blood colloidal osmotic pressure

Question 10

what occurs in venous end with a net filtration pressure of -7mmHg

Answer 10

reabsorption
- fluid reenters capillary as capillary hydrostatic pressure is less than blood colloidal osmotic pressure

Question 11

what is used to measure ejection fraction

Answer 11

2d doppler echocardiography

Question 12

what is raised JVP

Answer 12

jugular venous pressure
- vertical height from the sternal angle to the top of the pulsating column of blood in the internal jugular vein

Question 13

what is used to diagnose heart failure

Answer 13

Brain natriuretic peptide (BNP) or NT pro BNP
- measured using an immunoassay

Question 14

what does BNP and ANP indicate

Answer 14

The higher the ANP and BNP, the higher the risk of heart failure