EKG

Question 1

There is an EKG which has a normal PR interval, normal QRS width and magnitude, and it appears there is one dropped beat… What cardiac rhythm is this most likely?

Answer 1

Sinus block (pause)

Entire p, QRS, and T wave are absent.

Result of SA node’s failure to pace for one cycle

Question 2

Why is there a PR interval which takes approximately 0.12 to 0.20 seconds?

Answer 2

Conduction slows through the AV node to allow for the ventricles to fully fill.

Question 3

What are the characteristics of a 1st Degree AV Block?

Answer 3

PR interval >0.20 sec.

The PR Interval is consistently the same elongated time.

Question 4

What are some potential causes of 1st Degree AV Blocks?

Answer 4

"1st Deg. DIVE"
Drugs
Ischemia
Vagal tone
Electrolyte imbalances

Question 5

What are the characteristics of Mobitz 1 (Wenckebach)?

Answer 5

PR interval comes progressively longer with each cycle.

Dropped beat.

Question 6

What is happening in a 3rd Degree AV Block?

Answer 6

Impulses from above AV node cannot make it to the ventricles.

Self-pacing/Automaticity takes over. Junctional (40-60bpm) Ventricular (20-40)

Completely unrelated p-waves and QRS is the result b/c the Atria and Ventricles are not beating in conjunction.

Question 7

What leads will a Right Bundle Branch Block be visualized in? What appearance will it have?

Answer 7

V1 and V2 bunny ear appearance.

Bunny ear appearance because the left vent is beating before the right vent due to the block. The right ventricle is using conduction to from L to stimulate contraction.

Question 8

Where would a Left Bundle Branch Block be visualized in?

What appearance will it have?

Answer 8

V5 and V6 leads.

Appears as a notched R wave.

Question 9

What is the blood supply to each of the bundle branches? Right, L Anterior, and L posterior?

Answer 9

Right (LAD)
L Anterior (LAD)
L Posterior (RCA and LAD)

Question 10

How will a Left Anterior (Fascicular) Block present on an EKG?

Answer 10

L Axis deviation
Prominent S wave in lead 3
Norm/ Slightly Widened QRS complex
Q1S3

Question 11

Left posterior fascicular blocks will present with what axis deviation?

Answer 11

R axis deviation

Q1S3

Question 12

If atrial hypertrophy is present, what will be visualized on EKG?

Answer 12

Biphasic P waves.

RAH:  V1 Pos deflection
           Lead II (Peaked P wave >3mm amplitude) 

LAH: V1 Neg deflection
Lead II Notched P wave
Mitral stenosis

Question 13

Right ventricle hypertrophy is marked by….

Answer 13

Large R wave in V1

R waves progressively smaller V1 to V4

Question 14

Left ventricle hypertrophy is marked by…

Answer 14

Large downward S deflections in V1 to V3.

Large Peaked R waves in V4 and V5.

Question 15

What are some causes of Right Axis Deviation?

Answer 15

RVH: COPD or Pulmonary HTN
Normal in Children and tall/thin adults
Anterolateral MI
Dextrocardia

Question 16

What are some causes of Left Axis Deviation?

Answer 16

Pregnancy, Ascites, or Abd. tumor physically shifting heart position
LVH
Inferior Wall MI
LBBB
Wolff-Parkinson-White