Anatomy and Physiology of Heart Failure

Question 1

Describe the normal flow of blood through the vessels/chambers

Answer 1

1. Vena cava
2. Right atrium
3. Right ventricle
4. Pulmonary artery
5. Lungs
6. Pulmonary vein
7. Left atrium
8. Left Ventricle
9. Aorta
10. General circulation

Question 2

Primary Causes of Acquired Heart Disease

Answer 2

Chronic degenerative valve disease
Cardiomyopathy
Endocardial infection
Pericardial disease
Rate/rhythm abnormalities
Acute myocardial Injury

Question 3

Factors affecting tissue perfusion

Answer 3

Cardiac output (SV X HR)
Systemic arterial pressure
Venous pressure

Question 4

Preload

Answer 4

• The volume of blood/hydrostatic pressure within ventricles at the end of diastole
• End of ventricular filling
• End Diastolic Volume

Question 5

Afterload

Answer 5

• The pressure the heart works against to open up aortic valves in systole
• Systemic Vascular Resistance
• Arterial blood pressure is the primary factor

Question 6

Contractility

Answer 6

Force by which ventricle contracts
Determines blood in ventricle at the end of systole

Question 7

Consequence of reduced CO

Answer 7

Decrease in BP

Question 8

How does CDVD cause decreased BD?

Answer 8

Regurgitation means reduced forward flow
Reduced preload
Cardiac output decreases

Question 9

How does DCM cause decreased BD?

Answer 9

Heart can’t contract properly
Reduced contractility
Reduced stroke volume
Cardiac output decreases

Question 10

How does HCM cause decreased BP?

Answer 10

Ventricle can’t fill due to decrease in size
Reduced preload
Cardiac output decreases

Question 11

What mechanisms are activated to compensate for decreased blood pressure?

Answer 11

Sympathetic nervous system
RAAS
Cardiac enlargement

Question 12

Why is stimulation of SNS bad?

Answer 12

Pro-longed noradrenaline release

Question 13

Consequences of HR compensatory mechanism

Answer 13

Increase in heart rate means increase in oxygen demand

Question 14

Consequences of contractility compensatory mechanism

Answer 14

Increase in contractility means increase in oxygen demand

Question 15

Consequences of vasoconstriction compensatory mechanism in arteries

Answer 15

Increases afterload (higher pressure in aorta requires increased pressure to open aortic valve)
CO decreases
Valves leak more

Question 16

Consequences of vasoconstriction compensatory mechanism in veins

Answer 16

Increased volume returning to heart
Increased atrial pressures
Increased preload
Increased likelihood of pulmonary oedema leaking from LV into LA into PV

Question 17

Consequences of Salt and water retention compensatory mechanism

Answer 17

• Volume returned to heart goes up
• Volume of fluid in vessels goes up
• Pressure in capillaries goes up
• Oedema develops
  Leaks backwards from LA into PV

Question 18

Consequences of cardiac enlargement

Answer 18

• AV valves leak more as they are further apart
• Oxygen needs increase
• Oxygen supply decreases
• Cells die and result in scar tissue
• Contractility falls further

Question 19

Treatments for CHF

Answer 19

1. Reduce fluid build-up
   ○ Diuretics (furosemide)
2. Antagonise RAAS
   ○ ACE inhibitors
   ○ Aldosterone antagonists
3. Vasodilation
   ○ Pimobendan