ECG II

Question 1

What do you look for regarding sinus rhythm on an ECG?

Answer 1

Every P wave is followed by a QRS?

Every QRS is preceded by a P wave

The P wave is upright in leads I, II, and III

Question 2

How is heart rate determined when the rhythm is regular?

Answer 2

60/R-R interval (sec)

Question 3

What is the sequence for the “count-off” method?

Answer 3

300-150-100-75-60-50

Start at the first QRS and count the number of large boxes between two consecutive beats

Question 4

What is indicated by an isoelectric QRS complex inscribed by a limb lead?

Answer 4

The mean electrical axis of the ventricles is perpendicular to that particular lead

Question 5

How is the mean QRS axis calculated from an ECG?

Answer 5

Inspect limb leads I and II for the QRS to be upward in both, if it is, then axis is normal

Find the most isoelectric QRS in the limb leads, the mean axis is perpendicular to that lead

Inspect the lead perpendicular to that lead. If the QRS is upward, then the mean axis points to the (+) pole, if downward then towards the (-) pole

Question 6

Describe an ECG in right ventricular hypertrophy

Answer 6

Chest leads V1 and V2 record greater than normal upward deflection. R wave becomes taller than S wave in these leads

Causes right axis deviation

Question 7

Describe and ECG in left ventricular hypertrophy

Answer 7

Leads that directly overlie the left ventricle (V5, V6, I, and aVL) show taller than normal R waves

Leads on the other side (V1 and V2) show deepr-than-normal S waves

Question 8

Describe a right bundle branch block

Answer 8

Widened QRS complex

Abnormal terminal upward deflection (R’) in V1

Downward deflection (S wave) in V6

Question 9

Describe a Left Bundle branch block

Answer 9

Widened QRS

Broad, notched R in V6

Absent R and prominent S in V1

Question 10

Where does the left anterior fascicle run?

Answer 10

Anterior, superior, and lateral portion of the left ventricle

Question 11

Where does the left posterior fascicle run?

Answer 11

Through the posterior, inferior, and medial portion of the left ventricle

Question 12

What indicates a left anterior fascicular block?

Answer 12

Left axis deviation of the mean QRS axis

No widening of the QRS

Question 13

What indicates a left posterior fascicular block?

Answer 13

Right axis deviation of the mean QRS axis

No widening of the QRS

Question 14

What is a pathologic Q wave?

Answer 14

More prominent, typically greater than 1 small box in duration and a depth of greater that 25% of the height of the QRS

Indicates myocardial infarction

Question 15

What leads indicate an anteroseptal infarction with the presence of a pathologic Q wave?

Answer 15

V1

V2

Question 16

What leads indicate an anteroapical infarction with the presence of a pathologic Q wave?

Answer 16

V3

V4

Question 17

What leads indicate an anterolateral infarction with the presence of a pathologic Q wave?

Answer 17

I

aVL

V5

V6

Question 18

What leads indicate an inferior infarction with the presence of a pathologic Q wave?

Answer 18

II

III

aVF

Question 19

What indicates transient myocardial ischemia?

Answer 19

Transient ST segment depression and T wave flattening or inversions

Question 20

What results from acute ST segment elevation myocardial infarction (acute STEMI)?

Answer 20

Results in a temporal sequence of ST and T wave abnormalities

Question 21

What is present in an acute non-ST segment elevation myocardial infarction?

Answer 21

ST segment depression an/or T-wave inversion