Exam 2: EKG

Question 1

What is the total number of leads in a 12 Lead EKG?

Answer 1

10 leads: 4 Limb and 6 Chest leads

Question 2

Which leads represent the right ventricle?

Answer 2

V1, V2

Question 3

Which leads represent the left side of the heart?

Answer 3

V5, V6, Lead I, aVL

Question 4

What does the P-wave represent?

Answer 4

Atrial contraction

Question 5

What does the PR interval represent?

Answer 5

Time taken for excitation to spread from the SA node across the atrium to the ventricular muscle

Question 6

What does the QRS complex represent?

Answer 6

Ventricular contraction

Question 7

What does the ST segment represent?

Answer 7

Ventricular relaxation

Question 8

What does the T-wave represent?

Answer 8

Ventricular repolarization

Question 9

What patient details are important when reading an ECG?

Answer 9

Patient’s name, date of birth, hospital number, and location

Question 10

What situation details should be noted when reading an ECG?

Answer 10

Time of ECG, number of ECG in series, presence of chest pain, relevant clinical details

Question 11

How can the rate on an ECG be calculated?

Answer 11

• Count QRSs on one line and multiply by six
• Count large squares between R waves and divide 300 by this number

Question 12

What is the method to assess rhythm on an ECG?

Answer 12

Check if the rhythm is regular or irregular using the ‘paper test’
Dot next to QRS, see if marches out to next QRS etc

Question 13

What does axis represent in an ECG?

Answer 13

Sum of all electrical activity in the heart
The contraction travels from the atria to the R and L ventricles. As the LV is larger and more muscular, normal axis lies to the left.

Question 14

What indicates a normal axis in leads I and aVF?

Answer 14

Both have positive net deflections

Question 15

What causes left axis deviation?

Answer 15

Can be normal if the diaphragms are raised -Ascites, pregnancy
LVH
Left anterior hemiblock (see notes on heart block)
Inferior MI
Hyperkalaemia
VT
Paced rhythm

Question 16

What causes right axis deviation?

Answer 16

Normal in children or young thin adults.
Right ventricular hypertrophy (RVH) - Often due to respiratory disease
Pulmonary embolism (PE)
Anterolateral myocardial infarction
Left posterior hemiblock (rare)
Septal defect

Question 17

What can indicate complete heart block in P-waves?

Answer 17

P-waves not associated with QRS complexes

Question 18

What is ‘p mitral’ indicative of?

Answer 18

notched (or bifid) p-wave
Left atrial hypertrophy (can be caused by mitral stenosis)

Question 19

What can cause a prolonged PR interval?

Answer 19

First degree heart block

Question 20

What is a q-wave?

Answer 20

An initial downward deflection in the QRS complex
NORMAL –> in L-side chest leads (V5, 6, lead I, aVL) as they represent septal depolarization from L to R AND <0.04secs long (1 small square) and <2mm deep.
PATHOLOGICAL –> q-waves larger than this or present in other leads

Question 21

What is the normal width of a QRS complex?

Answer 21

< 0.12 secs (3 small squares)

Question 22

What can cause a wide QRS complex?

Answer 22

Bundle branch blocks
Hyperkalemia
Paced rhythm
Ventricular pre-excitation (WPW)
Ventricular rhythm
TCA poisoning

Question 23

What indicates ST segment elevation?

Answer 23

Infarction

Question 24

What indicates ST segment depression?

Answer 24

Ischemia

Question 25

What does the QT interval measure?

Answer 25

Time between the start of the q-wave and the end of the t-wave

Question 26

What are some causes of long QT?

Answer 26

MEDS: TCAs, Terfenadine, Erythromycin, Amiodarone, Phenothiazines, Quinidine METABOLIC: Hypothermia, Hypokalaemia, Hypocalcaemia, Hypothyroidism FAMILIAL: Long QT syndrome, Brugada syndrome, Arrhythmogenic RV dysplasia, IHD, Myocarditis

Question 27

What changes can hyperkalemia cause in T-waves?

Answer 27

Peaked T waves

Question 28

What is a classic presentation of hyperkalemia on an ECG?

Answer 28

Small p-wave Tall, tented (peaked) t-wave Wide QRS ***Widening of the QRS indicates severe cardiac toxicity

Question 29

What is a common normal variant for T-wave inversion?

Answer 29

Commonly inverted in aVR and V1

Question 30

What is indicated by tall R waves in V6 plus the depth of S waves in V1 greater than 35mm?

Answer 30

Left ventricular hypertrophy (LVH)

Question 31

Right Axis Deviation on EKG

Answer 31

lead I has a net negative deflection & aVF is positive

Question 32

Left Axis Deviation on EKG

Answer 32

lead I has a positive deflection and aVF has a negative deflection

Question 33

Tall Teaked P-waves

Answer 33

“p-pulmonale” and is indicative of right atrial hypertrophy often secondary to tricuspid stenosis or pulmonary hypertension. OR hypokalemia (known as “pseudo p-pulmonale”).

Question 34

PR interval may be shortened when

Answer 34

rapid conduction via an accessory pathway (WPW syndrome)

Question 35

QRS small or low voltage if

Answer 35

pericardial effusion, high BMI, emphysema, cardiomyopathy and cardiac amyloid.

Question 36

QRS tall if

Answer 36

LVH can also be tall in young, fit people (especially if thin)

Question 37

Criteria Suggestive of LVH

Answer 37

Height of R wave in V6 + the depth of the S wave in V1 --> If this value is >35mm = LVH.

Question 38

What is important to identify in patients with a history of collapse or transient loss of consciousness?

Answer 38

long QTc interval

Question 39

ST depression with down sloping is seen in

Answer 39

digoxin toxicity

Question 40

Significant ST-Segment Elevation/Depression

Answer 40

**S-T segment must be depressed or elevated by 1 or more millimeters in 2 consecutive limb leads OR **2 or more millimeters in 2 consecutive chest leads

Question 41

Reasons for Inverted/Flattened T-Wave

Answer 41

- Normal variant - Commonly inverted in aVR and V1 and often in V2 and V3 in people of Afro-Caribbean. - Ischemia - Ventricular hypertrophy (strain pattern) usually in lateral leads - LBBB (t-wave inversion in the anterolateral leads) - Digoxin - Hypokalemia (can cause flattened t-waves)