Heart failure

Question 1

What is heart failure

Answer 1

The heart cannot pump blood to the body at the rate that is required leading to SOB and fatigue

Question 2

What is the main feature if heart failure

Answer 2

Reduced cardiac output which is the result of systole which has 4 main determinants.
1. Contractibiity of myocardium
2. Preload of ventricles
3. Afterload applied to ventricles
4. The heart rate

Question 3

What is the cardiac output equation

Answer 3

SV x HR = CO

contractability of myocardium, preload and afterload affect CO.

Question 4

what happens when CO is reduced and heart fails?

Answer 4

Adaptations occur both early and chronic in the heart and systematically.

Question 5

Describe 2 early adaptations (1)

Answer 5

• Stroke volume decreases as a result end diastolic volume (blood in ventricles after systole) increases.
• This means ventricular chambers fill with more blood causing muscle fibres to lengthen and tighten to increase force of contraction.
• This results in attempt of ejecting excess blood (THE EDV) to compensate for the blood in the ventricles.

This is the Frank Starling law of the heart:
Higher EDV, stronger force of contraction, increase in SV and CO

Question 6

Describe 2 early adaptations (2)

Answer 6

1. Baroreceptors found within the heart/ aortic arch detect the reduction in CO.
2. Activates the sympathetic nervous system

Activation of Sympathetic NS:
- Stimulates contractability of myocardium
- This increases the HR
- And vasoconstriction of arterioles to maintain systemic vascular resistant and blood pressure.

This increases cardiac output

Question 7

What is a problem with one of the early adaptations

Answer 7

Long term activation of the sympathetic NS causes ventricular remodelling and dysfunction

Question 8

Why is ventricular remodelling a problem

Answer 8

Ventricular remodelling is the change is shape, size and function of the ventricles impacting cardiac performance

This particularly impacts the ejection fraction which is the percentage of blood volume ejected by the heart with each beat.

Question 9

Two types of ejection fraction

Answer 9

1. Reduced ejection fraction:
   - this is eccentric remodelling
   - <40%
   - Systolic heart failure
   - This is a PUMP issue
2. Preserved ejection fraction:
   - this is concentric remodelling
   - >50%
   - Diastolic heart failure
   - This is a filling problem/ not enough space.

Question 10

What are chronic adaptations

Answer 10

1. Reduced CO causes decreased renal perfusion ( the volume of blood delivered to the kidneys) which activates the RAAS system to regulate blood pressure. This contributes to ventricular remodelling and dysfunction which can then affect ejection fractions.
2. There is also a chronic increase in end diastolic volume and pressure due to the ejection fraction increasing the volume of blood left in the heart after contraction causing an increase in ventricular pressure due to ability to accomodate incoming blood leading to an increase in atrial pressure which dilates and remodels the left atrium over time.

The left atrial pressure increase is transmitted into the pulmonary veins which cause leakage and pulmonary congestion as well as it increases the pulmonary artery pressure which causes venous congestion leading to systematic oedema.

Question 11

Clinical manifestions of left HF

Answer 11

Pulmonary and systemic
1. Low CO output
- feeling faint
- fatigue- reduced 02 delievery
- exertional fatigue

2. Pulmonary congestion
   - SOB
   - cough, dry or pink frothy sputum is pulmonary oedema is present
   - oedema due to leakage and fluid accumulation
   - coarse base crackles
   - hypoxia

Question 12

Clinical manifestions of right HF

Answer 12

• Congestion of peripheral tissues causing peripheral oedema
• Increased JVP
• Liver congestion and enlargement
• Pitting lower limb oedema
• fluid retention, abdo swelling

All due to increased pressure in the systemic venous system