CV Part 2

Question 1

AV node allows for ______ from the _____ to the ______

Answer 1

Unidirectional conduction
Atria
His bundle

Question 2

His-Purkinje is the bridge between _____ and ______

Answer 2

AV nodal relay

Ventricular myocardium

Question 3

The refractory period of Purkinje fiber AP is

Answer 3

Inversely related to HR

Question 4

Order of events starting with SA node → Purkinje

Answer 4

SA node → atrial myocardium → AV node → bundle of His → left and right bundle branches → Purkinje fibers

Question 5

What’s the direction of ventricular depolarization in the myocardium?

Answer 5

From apex to base

Question 6

Upward deflections in ECG mean

Answer 6

Depolarization moving towards + electrode

Repolarization moving away from + electrode

Question 7

Negative deflections in ECG mean

Answer 7

Depolarization moving away from + electrode

Repolarization moving towards + electrode

Question 8

P wave

Answer 8

1st half = RA depol

2nd half = LA depol

Question 9

PR interval

Answer 9

Atrial depol

End of ventricular repol

Question 10

QRS complex

Answer 10

Ventricular depol

Question 11

S

Answer 11

End phase of ventricular depol

Question 12

ST segment

Answer 12

End of ventricular depol

Beginning of ventricular repol

Question 13

T

Answer 13

Ventricular repol

Question 14

TP

Answer 14

Isoelectric line

Electrically silent myocardium

Question 15

The cardiac electrical axis falls between

Answer 15

0 and 90 degrees

Question 16

2 common causes for axis deviation is

Answer 16

Hypertrophy

Pregnancy

Question 17

Supraventricular arrhythmias are problems in (3)

Answer 17

SA nodal
Atrial
AV junctional

(Anything before hitting the bundle branches)

Question 18

Ventricular arrhythmias originate in (2)

Answer 18

Bundle branches

Ventricular myocardium

Question 19

When are narrow QRS complexes formed? Why?

Answer 19

Supraventricular arrhythmias

Ventricular depol can still use fast conducting pathways

Question 20

When are widened QRS complexes formed? Why?

Answer 20

Ventricular/bundle branch arrhythmias

Signal has to go through the myocardium cell by cell

Question 21

Sinus tachycardia

Answer 21

HR > 100 bpm
Decrease P-P interval
Increase SA node AP

Question 22

Sinus bradycardia

Answer 22

HR < 60
Increase P-P interval
Decrease SA node AP

Question 23

What is atrial flutter and what is it the result of?

Answer 23

Rapid and regular atrial activity

Reentry

Question 24

Ventricular rate depends on

Answer 24

Degree of AV delay

Question 25

Premature atrial contractions (PAC) causes

Answer 25

Premature depol leading to atrial contraction

Question 26

AV node dysfunction is known as _____ and is based on ______

Answer 26

Heart block | Degree of severity

Question 27

Primary heart block: How is the ECG affected? What is it caused by?

Answer 27

Prolonged PR interval | Longer conduction time in AV node/bundle of His

Question 28

Second degree heart block: How is the ECG affected? What is it caused by?

Answer 28

Ratio of P:QRS is greater than 1 | Increased refractory period of AV node/bundle of His → less excitable

Question 29

Third degree heart block? How is the ECG affected? What is it caused by?

Answer 29

Messy- P waves can be before, within or after QRS complex | No atrial impulses reach the ventricles

Question 30

What is an escape rhythm?

Answer 30

Pacemakers that take control of cardiac rate and rhythm when the relay system doesn't work properly

Question 31

AV Junctional

Answer 31

Escape rhythm if the block is in the AV node 40-50 bpm Can maintain hemodynamic stability

Question 32

Ventricular (think AV node)

Answer 32

Escape rhythm when block is distal to AV node 30-40 bpm Unstable and slow rhythm

Question 33

What is fibrillation?

Answer 33

Arrhythmia hat prevent effectual contraction of atria/ventricles

Question 34

Atrial Fibrillation (4)

Answer 34

Rapid twitches or contractions of muscle fibrils No discernable P wave Irregularly irregular HR and pulse Lose atrial contribution to CO

Question 35

Ventricular fibrillation

Answer 35

Blood not effectively pumped from the ventricles Apply electric current to defibrillate myocardium for a brief period of refraction Hope to get SA node in control again

Question 36

Bundle branch block

Answer 36

Cause widened QRS | Have to use myocyte-myocyte conduction

Question 37

Premature ventricular contraction (PVC)

Answer 37

Uncoordinated ventricular depol Widened QRS No P wave associated with aberrant QRS

Question 38

Ventricular tachycardia

Answer 38

Wide QRS complex | Vary in shape and rhythm

Question 39

Antiarrhythmic drugs targets _____ and prevents ________

Answer 39

SNS | Activation of Ca, Na or K channels