Physiological Basis of ECG part 1

Question 1

When the SA nodes causes atria to depolarize from right to left this creates what part of the ECG?

Answer 1

P wave

Question 2

When the AV node delays signal this creates what part of the ECG?

Answer 2

PR Interval

Question 3

When the ventricles depolarize generally from right to left, form apex to base, from interior to exterior this creates what part of the ECG?

Answer 3

QRS complex

Question 4

When the AP phase 2 delayed repolarization of ventricles this creates what part of the ECG?

Answer 4

ST segment

Question 5

When the ventricles repolarize generally from left to right, base to apex this creates what part of the ECG?

Answer 5

T wave

Question 6

The p wave represents what phase of AP in atrial muscle?

Answer 6

Phase 0

Question 7

At the end of P wave and at the ST segment, all cells are?

Answer 7

Depolarized

Question 8

The QRS complex represents what phase of AP in ventricular muscle?

Answer 8

Phase 0

Question 9

The T wave represents what phase of AP in ventricular muscle?

Answer 9

Phase 3

Question 10

How long is the PR interval?

It should not be longer than?

Answer 10

1) 0.16 s

2) 0.2 s

Question 11

How long is the QT interval?

Answer 11

0.35 ms

Question 12

What is the trick to approximating HR on an ECG?

Answer 12

Start at QRS complex and count the boxes to the next QRS complex and start from 300, 150, 100, 75, 60, 50

Question 13

Where is the placement for lead 1?
Lead 2?
Lead 3?

Answer 13

1) RA to LA
2) RA to LL
3) LA to LL

Question 14

The augmented vector, foot lead (aVF), is placed?
aVR?
aVL?

Answer 14

1) RA+LA to LL
2) LL+LA to RA
3) LL+RA to LA

Question 15

V1 and V2 are mainly?

V4, V5, V6 are mainly?

Answer 15

1) Negative

2) Positive

Question 16

The mean electrical axis is the average direction of spreading AP in ventricles, where does it use the average amplitude of QRS?

Answer 16

Leads 1 and aVF

Question 17

On a mean electrical axis, when going from right to left lead I is?
When going from left to right?

Answer 17

1) Positive

2) Negative

Question 18

On a mean electrical axis, when going from top to bottom the aVF lead is?
When going from bottom to top?

Answer 18

1) Positive

2) Negative

Question 19

On a mean electrical axis, when both leads I and aVF are positive then there is?
If only lead I is negative?
If only aVF lead is negative?

Answer 19

1) Normal mean electrical axis
2) Right axis deviation
3) Left axis deviation

Question 20

Right axis deviation usually is present with?

Left axis deviation?

Answer 20

1) Right ventricular hypertrophy

2) Left ventricular hypertrophy

Question 21

Atrial repolarization occurs during?

Answer 21

QRS complex

Question 22

What is the state of the atrial myocytes at the peak of the T wave?
Ventricular myocytes?

Answer 22

1) Fully replarized

2) Partially repolarized

Question 23

When is the calcium influx greatest for atrial myocytes?

Answer 23

PR interval

Question 24

There are three pacemaker nodes within the heart, what are the bpm for:
SA node?
AV node?
Purkinje fibers?

Answer 24

1) 60-100
2) 40-60
3) 15-40

Question 25

What lead do we see the most electrical activity within the heart?

Answer 25

Lead II

Question 26

If there is a P wave on an ECG, then we have what type of rthythm?

Answer 26

Sinus rhythm (started in SA node)

Question 27

How does the cellular composition of the atrial myocytes change with the beginning of the P wave?

Answer 27

Rapid increase in Na

Question 28

On an ECG the ST segment should be?

Answer 28

Isoelectronic (at baseline)

Question 29

Where are the leads in relation to coronary arteries?
Inferior?
Septal?
Anterior?
Lateral?

Answer 29

1) II, III, aVF
2) V1, V2
3) V3, V4
4) I, aVL, V5, V6

Question 30

What is the criteria for a STEMI?

Answer 30

ST elevation in two or more contiguous leads

Question 31

What is the criteria for a pathological Q wave?

Answer 31

Wide, inverted Q wave in two or more contiguous leads

Question 32

What artery is associated with anterior and septal leads?
Inferior leads?
Lateral leads?

Answer 32

1) Left anterior descending
2) Right coronary artery
3) Circumflex artery