deck 4

Question 1

How does AC electrical interference usually appear on EKG (frequency and morphology)?

Answer 1

1. very high frequency background noise → cycle length of 16 ms (60 cycles per second)
2. morphology is ~sine wave

Question 2

Which type of ATach may appear similar to sinus tachycardia?

Answer 2

crista terminalis Atach

• crista terminalis AT may look like sinus tach because it has same p wave axis

Question 3

P wave axis for coronary sinus AT? (2)

Answer 3

IVC is relatively right-sided & low → P axis is:

1. Superior (negative in II, III, aVF)
2. leftward/posterior (negative in V1)

Question 4

P wave characteristics for SVC AT?

Answer 4

same axis as for SR but w/ p-pulmonale morphology

Question 5

P wave morphology for pulmonary vein AT? (2)

Answer 5

PVs are left-sided and posterior → P axis is:

1. rightward (negative or biphasic in lead I)
2. anterior (positive in V1)

Question 6

Appropriate anatomic location for posterior EKG leads?

Answer 6

All 3 leads should be placed 5th intercostal space posteriorally:

• V7 - left posterior axillary line
• V8 - left midscapular line
• V9 - just left of spine

Question 7

EKG shows the following:

• inferior wall injury pattern
• 1-2 mm ST depression in V1-V3
• normal R wave progression

What can you do next to further characterize extent of injury?

Answer 7

place posterior leads

• DDx of ST depressions in V1-V3: ISCHEMIA, POSTERIOR INJURY, or RECIPROCAL CHANGES from inferior injury
• posterior leads will help diagnose posterior injury in pt w/ Rt precordial ST depressions

Question 8

Pt with SSCP has EKG w/ following properties:

• normal 12 lead EKG
• Q waves in leads V7 and V8 on posterior EKG

Name 3 non-angiographic findings that are associated with this presentation.

Answer 8

presentation = “silent MI” w/ posterior infarct → is a/w:

1. elevated biomarkers
2. inferolateral hypokinesis on echo
3. ischemic MR on echo

Question 9

Which drug is most commonly associated with MAT?

Answer 9

aminophyilline

Question 10

2 potential cardiac effects of atropine?

Answer 10

1. sinus tachycardia
2. paradoxical sinus bradycardia (only with low-doses)

Question 11

Name 4 causes of AIVR.

Answer 11

All the following causes of AIVR involve increased extracellular K+:

1. dig toxicity
2. hyperkalemia
3. reperfusion injury
4. ischemia

Question 12

Best way to approach unknown rhythm on EKG board exam?

Answer 12

four step process for determining unknown rhythm:

1. determine ventricular rate & morphology
2. determine atrial rate & morphology
3. AV dissociation present?
4. determine the pacemaker cell location based on above

Question 13

Which 2 things should you look for when assessing ventricular morphology of unknown rhythm?

Answer 13

1. width of QRS: narrow-complex vs. wide complex
2. bundle branch block patterns: right bundle vs. left bundle