EKG

Question 1

Analyze on every ECG

Answer 1

1. Rate
2. Rhythm
3. Interval
4. Axis
5. Ischemia
6. Pacemaker

Question 2

one large box represents…

Answer 2

• 0.2 sec of time
• 5mm of amplitude

Question 3

one small box represents…

Answer 3

• 0.04 sec of time
• 1 mm of amplitude

Question 4

high lateral

Answer 4

• I
• aVL

Question 5

lateral

Answer 5

• V5
• V6

Question 6

septal

Answer 6

• Vi
• V2

Question 7

anterior

Answer 7

• V2
• V3
• V4

Question 8

inferior

Answer 8

• II
• III
• aVF

Question 9

rate

Answer 9

• Assume standard paper speed 25 mm/sec
• Regular Rhythm

– Count the number of large boxes between P waves, R waves or pacer spikes

– Beats per minute = 300 / # of large boxes

Question 10

sinus bradycardia

Answer 10

•<60 bpm

Question 11

sinus tachycardia

Answer 11

• >100 bpm
• Sinus tachycardia

– Regular

– P wave before each QRS

Question 12

irregular rate

Answer 12

•differences in bpm across the ECG

Question 13

rhythm

Answer 13

• Most difficult and complex part of ECG interpretation
• Computer interpretation often wrong
• Need to look at:

– P wave morphology

– QRS morphology

– P:QRS relationship

P:QRS = 1

– P wave precedes every QRS

– Sinus rhythm

Question 14

if P wave FOLLOWS every QRS…

Answer 14

P:QRS = 1

– P wave follows every QRS

– Super ventricular tachycardia (SVT)

Question 15

if P:QRS < 1 or NO P waves…

Answer 15

P:QRS < 1 or NO P WAVES

– Atrial fibrillation

– Irregular irregular

Question 16

if P:QRS > 1 or NO P wave…

Answer 16

P:QRS < 1 or NO P WAVES

– Junctional rhythm

– From below the AV node

Question 17

P:QRS < 1 or NO P wave…

Answer 17

P:QRS < 1 or NO P WAVES

– Ventricular rhythm

– From the ventricle, wide complex

Question 18

P:QRS

Answer 18

Question 19

Answer 19

• P wave 0.8 - .10 ms
• PR interval 0.12 - 0.20 ms
• QRS complex 0.06 - 0.10 ms
• QTc <0.44 ms

Question 20

PR interval

Answer 20

• Represents conduction time from the onset of atrial depolarization to onset of ventricular activation
• Measure from beginning of P wave to first deflection of QRS complex
• Normal PR duration 0.12 – 0.20 sec
• Increased PR duration > 0.20 sec

1 big block!

Question 21

1st Degree AV Block

Answer 21

• The distance from the beginning of the P wave until the beginning of the QRS complex is > 0.20 sec.
• This is first degree AV block.

Question 22

QRS interval

Answer 22

•<120 ms

smaller than 3 small boxes!

Question 23

RBBB

Answer 23

• prolonged QRS
• Extra deflection in V1 reflects the rapid depolarization of the left ventricle followed by the slower depolarization of the right ventricle. The last electrical activity is thus to the right, or towards lead V1.

Question 24

LBBB

Answer 24

• prolonged QRS interval
• Normally the septum is activated from left to right.
• In LBBB, the normal direction of septal depolarization is reversed (becomes right to left), as the impulse spreads first to the RV via the right bundle branch and then to the LV via the septum.
• This sequence of activation extends the QRS duration to > 120 ms. The overall direction of depolarization (from right to left) produces tall R waves in the lateral leads (I, V5-6) and deep S waves in the right precordial leads (V1-3), and usually leads to left axis deviation.
• difficult to call ischemia in LBBB
• As the ventricles are activated sequentially (right, then left) rather than simultaneously, this produces a broad or notched (‘M’-shaped) R wave in the lateral leads.

Question 25

QT interval

Answer 25

* Represents total duration of ventricular systole * Measure from beginning of QRS to end of T wave * Normal QT \< 0.35 – 0.43 sec * Increased QT \> 0.44 sec

Question 26

axis

Answer 26

•Represents major vector of ventricular activation

Question 27

Answer 27

Question 28

ST interval

Answer 28

•Abnormalities of the ST segment can suggest ischemia – After depolarization & repolarization period •Normal is to be “isoelectric” – ST depression = ischemia – ST elevation = active infarction

Question 29

ST interval criteria

Answer 29

•Infarction: New ST segment elevation at J-point in two contiguous leads – \> 1 mm in all leads except V1&V2 – In V1&V2, \>2mm in men \> 40 yo, \> 2.5 mm in men \< 40 yo, \> 1.5mm in women •Ischemia: New horizontal or downsloping ST changes \> 0.5 mm in two contiguous leads – And / or T wave inversion \> 1 mm with prominent R wave •The higher the ST segment elevation the clinically more severe the infarction.

Question 30

Other causes of ST changes

Answer 30

* LBBB * RBBB * LVH * RVH * pericarditis * BER

Question 31

old infarctions

Answer 31

* Old infarctions are represented as lack of R waves OR presence of Q waves * No all Q waves are pathologic Q waves can be related to: – Anatomic and positional effects – Myocardial injury or loss (duration, extent, size of MI) – Ventricular enlargement – Altered conduction (LBBB or pre-excitation pattens)

Question 32

2nd Degree AV Block

Answer 32

* not all P waves lead to QRS * Type 1 * Type 2

Question 33

2nd Degree AV block Type 1

Answer 33

* Mobitz I (also known as Wenckebach) * Lesser degree of AVB Variable * PR interval Usually narrow * QRS Usually above the HIS complex in AV node * Usually no pacer needed

Question 34

2nd Degree AV block Type 2

Answer 34

* Mobitz II * Higher degree of AVB * PR interval the same * Can have WIDE QRS complex * Usually below the AV node * Increased incidence of progressing to 3rd degree * May need pacer

Question 35

3rd Degree AV block

Answer 35

* Regular p waves and QRS, but INDEPENDENT of each other * Acquired vs. congenital * Pacer often required * No electrical connection between atrial and ventricles * no P waves lead to QRS

Question 36

supraventricular tachycardia

Answer 36

* Rate 160 bpm --\> tachycardia * No p waves, regular --\> SVT * Normal axis, narrow complex * Non-specific T wave flattening

Question 37

torsades

Answer 37

* Multiple ventricular foci with the resultant QRS complexes varying in amplitude, axis and duration * Torsade de pointes (TdP) – QT prolongation – QRS complexes “twist” around the isoelectric line. (For TdP to be diagnosed, the patient has to have evidence of both VT and QT prolongation)