Heart failure

Question 1

How can valve pathology present in HF?

Answer 1

Blood inflow from the SVC/ IVC intro the R atrium, this flows into the R ventricle. When R ventricle contracts, normally the tricuspid valve will be closed and there will be no backflow into the systemic venous circulation. If valve pathology, blood flows back into venous system.

Same with the L side, if the mitral valve fails, everytime the L ventricle contracts, blood may be pushed back into the pulmonary veins –> leads to pulmonary HTN, pulmonary oedema in LHF.

Question 2

What are the key functions of the heart?

Answer 2

• pump blood to lungs for oxygenation
• pump blood to the body
• deliver oxygen and nutrients
• remove waste

Question 3

Describe the layers of the heart

Answer 3

Three layers to the heart wall:

Endocardium –> squamous cell epithelium

Myocardium –> involvuntary striated muscle and collagen in a complex swirl. This squeezes all the blood out.

Epicardium

Plus a double membraned sac:

Pericardium –> fixes the heart in place, lubricates and prevents infection

Question 4

How is the cardiac AP initated?

Answer 4

Muscles have pacemakers cells that show autorhythmicity

Initate an internal cardiac AP

under external influence (paraSNS vs SympNS)

Question 5

What type of valves does the heart have?

what is their role?

How do these valves fail?

What are the 4 valves of the heart?

Answer 5

The heart has unidirectional valves that prevent backflow.

Valves fail either by:

1) stenosis – >calcification of the valves that become fixed, do not allow as much blood through, ventricles work harder and hypertrophy.
2) regurgitation of the valves –> blood backs up into atria, e.g. mitral valve failure blood backs up into pulmonary veins causing congestion, ovetime causes ventricles and veins to dilate.

4 valves:

1) Tricuspid
2) Pulmonary
3) mitral
4) aortic

Question 6

What is the equation for CO?

What is the normal CO?

What is Ejection fraction?

What is normal EF?

Answer 6

CO = SV x HR

Standard SV 70 ml per beat

BPM around 70

70 x 70 = 4900 ml/min

CO = 5L/ min

With average EF of 50-70%.

EF = the percentage of blood that is ejected from the ventricles during systole.

Question 7

What are the causes of HF?

Answer 7

1. Coronary artery disease
   1.