Cardiac Haemodynamics

Front 1

Identify the major coronary arteries

Back 1

Hint 1

Left coronary artery
Right coronary artery
Left anterior descending artery LAD
Posterior descending artery (posterior interventricular artery)
Left circumflex artery
Right marginal artery

Front 2

Define collateral circulation?

And its significance in ischaemic heart disease.

Back 2

Coronary arteries can join and provide a collateral circulation to the cardiac muscle, bypassing occluded vessels and assisting in perfusing the myocardium.

Particulary in older people with established ischaemic heart disease, which means they have the capacity to tolerate occluded vessels.

Front 3

Hypertension as it applies to left ventricular haemodynamics

(in relation to afterload)

Back 3

Hypertension creates a situation where the right ventrical is pumping the usual volume of blood (at a faster rate) through the lungs and into the left ventricle which, because of its high aortic afterload, cannot pump the same volume of blood out and so the lungs become congested.

Contributing to left ventricular failure and pulmonary oedema.

Front 4

Define hypertension?

Back 4

Hypertension exist if Diastolic pressure is greater than 95mmHg

Front 5

4 properties of cardiac muscle?

Back 5

1. Excitability
The cells ability of being responsive to a stimuli.

2. Automaticity
The capability for self depolarization.

3. Conductivity
A cells ability to conduct an impulse from one cell to another.

4. Contractility
The ability to shorten or develop tension

Front 6

Intrinsic depolarisation rates of the SA node, AV node & Ventricular Cells?

Back 6

SA node 60-80 per minute

AV node 40-60 per minute
Ventricular cells 15-40 per minute

Front 7

Briefly describe all elements of
The Cardiac Cycle?

Back 7

Section 1 - Atria and ventricles are both resting (passively filling)

Section 2 - Atria contract, ventricles still resting
Discuss atrial kick (30% of ventricular filling) - the priming force contributed by atrial contraction immediately before ventricular systole, that acts to increase the efficiency of ventricular ejection due to acutely increased preload

Section 3 - Ventricles contracting, atria resting (passively filling)

Front 8

How long does Atrial systole/diastole & Ventricular systole/diastole last?

Back 8

0.1 sec Atria systole
0.3 sec Ventricular systole
0.7 sec Atria diastole
0.5 sec ventricular diastole

Front 9

Three important functions of the ventricular diastole?

Back 9

Ventricular Filling
Ventricular Resting
Ventricular Perfusion

Front 10

The dangers of sustained tachycardias with reference to the 3 important occurrences of diastole?

Back 10

Cardiac cycle time is reduced to a tachycardia.

Reduced Ventricular filling time, reduced preload, reduced cardiac output.

Reduced Ventricular resting time, reduced strength, reduced contractility, reduced cardiac output.

Reduced ventricular perfusion, increased ischaemia and pain, reduced contractility, reduced cadiac output.

Front 11

The primary function of ventricular systole?

Back 11

Contraction of the ventricles, forcing blood into the aorta and pulmonary arteries

Front 12

The starling mechanism?

How can this mechanism be compromised or enhanced by pathophysiology factors and paramedic interventions?

Back 12

The greater the myocardium is stretched , the greater the force of it's contraction to a point.

Front 13

Define Preload?

Back 13

The tension in a chamber of the heart at the end of diastole.

Just befor it is about to contract.

Front 14

Define After-Load?

Back 14

After-Load is the pressure against which the heart must pump.

It is a result of peripheral vascular resistance.

If referring to left and right ventricular after-load, we are talking about diastolic pressure in the aorta and pulmonary artery respectively.

Front 15

The main parasympathetic nerve that controls the heart?

Back 15

Through the Vagus nerve.

The 10th cranial nerve

As a continuous restraining influence on the heart.

Front 16

The main sympathetic nerves that control heart rate?

Back 16

Nerve fibres called ganglia, originating in the thoracic region of the spinal cord.

Front 17

Function of the cardiac skeleton?

Back 17

The fibrous or fibrocartliaginous framework that supports and gives attachment to the cardiac muscle fibres and valves, and the roots or the aorta and pulmonary trunk.

Front 18

Factors that may compromise coronary perfusion?

Back 18

Heart Rate (tachycardia)
Collateral circulation
Electrical disturbances (VT,VF,PVC's)
Ischaemia from coronary vessel occlusion

Front 19

Explain the term 'functional syncytium' as it applies to the heart's conductive system

Back 19

Syn (with or together)
+
cyt (cell)
+
ium (biological structure)

The atria make up one syncytium while the ventricles make up the other.

Hint 19

Cardiac muscle cells are mechanically, chemically, and electrically connected to one another, thus, the entire tissue resembles a single, enormous muscle cell. For this reason, cardiac
muscle has been called a functional syncytium.
This is also true of smooth muscle.

Front 20

The cardiac haemodynamic problems often associated with bradycardias?

Back 20

Bradycardia can be a serious problem if the heart doesn't pump enough oxygen-rich blood to the bodies vital organs.

Reduced filling pressure = reduced stroke volume and essentially Cardiac output.