ECG

Question 1

Which leads are anterior, inferior, lateral & septal?

Answer 1

Question 2

This is a routine preoperative ECG taken on a 66-year-old woman scheduled for cataract surgery. She denies all cardiovascular symptoms.

1. Does her ECG suggest that she has had a “silent” inferior myocardial infarct?
2. Should she have further evaluation, eg: a stress thallium study, prior to operation?

Answer 2

1. Despite the Q wave and the negative T wave in lead III, this ECG would be considered within normal limits.

(This isolated Q wave in lead III with a negative T wave is a common normal variant. Remember that lead III is “BIPOLAR”, that is, it is the instantaneous difference in voltage recorded between the left leg and left arm. Therefore it has no special geographic significance in and of itself e.g.: it does not necessarily reflect the inferior wall of the heart.

Notice that when you record lead III, the positive pole of your galvanometer (or ECG recorder) is attached to the left leg and the negative pole is attached to the left arm. Therefore, lead III represents the instantaneous difference in voltage between these two points of the body.

III = aVF - aVL

The voltage recorded at aVL is being continuously subtracted from aVF)

2. No further cardiac evaluation is needed

Question 3

What is the order of leads that must be looked at to diagnose an inferior MI?

Answer 3

aVF, III, II

(aVF contributes indirectly to leads III and II)

Question 4

59-year-old man with hypertension, CAD and bypass surgery 2-years earlier, complicated by post-operative atrial fibrillation. Presents now with palpitations and pre-syncope.

1. Is this atrial fibrillation?
2. How do you think the rhythm relates to the symptom of pre-syncope?

Answer 4

1. No it’s atrial flutter (saw-toothed waves)
2. Atrial flutter and atrial fibrillation can cause pre-syncope, but it is relatively uncommon. More commonly, the hypoperfusion symptom comes at the time of abrupt spontaneous termination of the arrhythmia.

Question 5

What 3 abnormalities does this ECG show?

Answer 5

• ATRIAL FLUTTER
• LVH
• left anterior fascicular block

Question 6

Which leads can atrial flutter be best identified in?

Answer 6

inferior leads (

Question 7

What is the atrial rate?

Answer 7

Remembering that each small box is 40 msec and each big box is 200 msec, you can use calipers and determine that the atrial cycle length (f-f interval) is ~ 230 msec.

Divide 60 by 0.230 seconds to get the rate.

The answer is 260 bpm.

Therefore the flutter rate is 260.

Atrial flutter is often exactly 300 bpm but can be slower when the atrial size is larger or when the patient is taking an antiarrhythmic drug.

Question 8

What are the typical characteristics of type I atrial flutter?

Answer 8

Question 9

A 57-year-old woman is seen urgently for chest pain of two hours duration. The pain is mild, continuous, aching and localized to the left upper chest and shoulder. No previous cardiovascular problems.

Answer 9

1. no
2. repeat ECG with proper lead placement

(repeat ECG showed chest pain was musculoskeletal)

Question 10

51 yr old male with no prior cardiac history presents with mid-sternal chest discomfort.

1. Is there ECG evidence of injury or ischemia?
2. Is this patient having an MI? If so, in what anatomic distribution?

Answer 10

1. YES
2. Antero-septal

Question 11

What does ST elevation indicate?

Answer 11

current of injury

Question 12

When can MI be inferred?

Answer 12

When there is ECG evidence of necrosis i.e. when pathological P waves develop (??)

Question 13

How are the different types of MI determined? e.g. anterior

Answer 13