Cardiac Condiction

Question 1

What is the Bachmann’s bundle?

Answer 1

The Bachmann’s bundle takes the impulse from the SA node (in the right atrium) over to the left atrium so that both contract at the same time.

Question 2

What are three properties of heart cells?

Answer 2

Automaticity
Excitability
Conductivity

Question 3

What is automaticity?

Answer 3

The ability of heart muscles to spontaneously initiate an action potential.

Question 4

How fast does the SA node fire?

Answer 4

60-100/min

Question 5

How fast does the AV node fire?

Answer 5

40-60/min

Question 6

How fast do the Purkinje fibres fire?

Answer 6

20-40/min

Question 7

What is excitability?

Answer 7

The ability of heart cells to respond to an impulse and then generate its own action potential.

Question 8

What is conductivity?

Answer 8

The ability of heart cells to conduct impulses.

Question 9

What is happening during the P wave on an ECG?

Answer 9

This is the depolarization wave. The action potential moves from the SA node to the AV node & over to the left atrium.

Question 10

What is the PR interval on an ECG?

Answer 10

The impulse is moving through the AV node, Bundle of His, left and right bundle branches, and Perkinjes.

Question 11

What is occuring during the QRS complex on an ECG?

Answer 11

The impulse is travelling through the ventricular wall.

Question 12

What is occuring during the T wave on an ECG?

Answer 12

The ventricles are repolarizing.

Question 13

What is a U wave on an ECG?

Answer 13

The repolarization of the Perkinjes.

Question 14

What is sinus bradycardia?

Answer 14

A heart rate

Question 15

What does sinus bradycardia indicate?

Answer 15

It may be normal in some people, but also may indicate ischemia (due to not enough blood pumping).

Question 16

What is sinus tachycardia?

Answer 16

A heart rate >100

Question 17

What are the signs and symptoms of sinus bradycardia?

Answer 17

Signs and symtpoms of decreased perfusion.

Question 18

What does sinus tachycardia indicate?

Answer 18

Ischemia, hypoemia. (may be normal with exercise or fever)

Question 19

What are the effects of sinus tachycardia?

Answer 19

Increases myocardial workload.
Decreases coronary artery perfusion (because the coronary artery fills with blood during diastole, and the diastolic period is shortened with tachycardia.)

Question 20

What is sinus arrest?

Answer 20

Failure of SA node, usually intermittent.

Question 21

What is sick sinus syndrome?

Answer 21

SA node not working perfectly, d/t SA node injury

Question 22

What are premature atrial complexes? (PAC)

Answer 22

Early depolarization originating in the atria (not SA node). These are common.

Question 23

What is paroxysmal supraventricular tachycardia (PSVT)?

Answer 23

120-140 beats/min

Sudden onset and cessation

Question 24

What are the causes of paroxysmal supraventricular tachycardia?

Answer 24

Ischemia (SA node)
Re-entry
(Wolff-Parkinson-White Syndrome)

Question 25

What is atrial flutter?

Answer 25

Ectopic atrial tachycardia 240-450/min

Question 26

What is the cause of atrial flutter?

Answer 26

Re-entry (impulse goes back and forth between the SA and AV nodes instead of in the normal atrium to ventricles pattern).

Question 27

What is atrial fibrillation?

Answer 27

Chaotic depolarization of the atria with only occasional contraction.

Question 28

What are the causes of atrial fibrillation?

Answer 28

Heart failure | Myocardial infarction

Question 29

What is the effect of atrial fibrillation on cardiac output (and why)?

Answer 29

Because of poor emptying of the atria during diastole, there is poor filling of the ventricles. Therefore, cardiac output is decreased.

Question 30

What are the signs of atrial fibrillation?

Answer 30

Irregularly irregular heartbeat Pulses will be irregular and with varying strength Low BP (All other systems will exhibit the Signs and Symptoms of decreased cardiac output).

Question 31

What are heart blocks?

Answer 31

AV node/Bundle of His/bundle branch issue.

Question 32

What is first degree atrioventricular block?

Answer 32

Consistent long PR interval, followed by a QRS. (People can live with this).

Question 33

What is second degree AV block?

Answer 33

The AV node isn't working perfectly, but it still can work.

Question 34

What are the two kinds of type two AV block?

Answer 34

Mobits type 1 - Increasing PR until QRS dropped | Mobitz type 2 - Occasional dropped QRS, but the PR is stable.

Question 35

What is third degree AV block?

Answer 35

There is no electrical communication between atria and ventricles.

Question 36

How does the heart beat during third degree AV block?

Answer 36

Because there is no communication between the atria and ventricles, they beat independently of each other. (The purkinje fibres still initiate an impulse for the ventricles to contract.)

Question 37

What are premature ventricular complexes (PVC)?

Answer 37

The impulse travels the wrong way through the heart (ventricles to atrium).

Question 38

What is ventricular tachycardia?

Answer 38

Excessive ventricular electrical activity. (Non-stop PVC's).

Question 39

What is torsades de pointes?

Answer 39

A form of ventricular tachycardia.

Question 40

What is ventricular fibrillation?

Answer 40

sdhaskldghj | The ventricles are fluttering. There is no cardiac output.

Question 41

What is asystole?

Answer 41

No cardiac activity.