05b: Arrhythmia

Question 1

In EKG, PR-interval starts at (X) and ends at (Y).

Answer 1

X = beginning of P wave
Y = beginning of QRS

Question 2

In EKG, PR-segment starts at (X) and ends at (Y).

Answer 2

X = end of P wave
Y = beginning of QRS

Question 3

Normal range of PR interval.

Answer 3

3-5 small boxes (0.12-0.2s)

Question 4

Normal range of QRS.

Answer 4

Less than 2.5 small boxes (under 0.1s)

Question 5

A sinus arrhythmia is present if shortest and longest (X) interval/segment varies by more than (Y) sec.

Answer 5

X = P-P interval
Y = 0.16s (4 small boxes)

Question 6

EKG: The normal P wave contour is replaced by high frequency, undulating, and often saw tooth appearing waves. Which condition is this?

Answer 6

Atrial flutter

Question 7

In atrial flutter, the cause of the oscillating waves on EKG is considered to result from (X).

Answer 7

X = a reentrant rhythm

Question 8

(X) atria, that be a consequence of stenotic AV valves, would be more likely to develop a reentrant rhythm. Why?

Answer 8

X = Dilated;

The longer it takes for the wave of depolarization to spread, the more likely the tissue initiating the excitation can be excited again (out of refractory period)

Question 9

It has been observed that an abnormal impulse reaching nodal tissue during its refractory period tends to (increase/decrease) the refractory state.

Answer 9

Increase (prolong) - safety mechanism

Question 10

Atrial fibrillation is similar to (X) condition, but the (higher/lower) amplitude waves have (lower/higher) frequency and lack the (Y) seen in (X).

Answer 10

X = atrial flutter
Lower;
Higher;
Y = regularity

Question 11

Explain why atrial flutter and A-fib (do/don’t) seriously hamper cardiac output at rest.

Answer 11

Don’t;

Most ventricular filling is passive, so the lack of productive atrial contraction doesn’t impact CO at rest

Question 12

List some conditions under which atrial flutter/fib would especially impact CO.

Answer 12

1. Exercise (passive fill time of ventricles reduced)

2. AV valve stenosis (high flow resistance)

Question 13

PACs (premature atrial contractions) are common and can be caused by:

Answer 13

alcohol, caffeine, stress or lack of sleep

Question 14

Where would you expect to see the (X) wave in spontaneous, premature junctional excitation that originates in the AV node and spreading to ventricles first?

Answer 14

X = P

After QRS (atria excited after ventricles)

Question 15

First-degree (X) block is identified by:

Answer 15

X = AV

a lengthening of the PR interval

Question 16

Second-degree (X) block is identified by:

Answer 16

X = AV

the failure of some but not all P-waves to be conducted into the ventricle

Question 17

Third-degree (X) block is identified by:

Answer 17

X = AV

complete dissociation of electrical activity in the atria and ventricles (SA an AV nodes fire at their own rhythms)

Question 18

In (X) degree heart block, the (SA/AV) node fires at significantly lower frequency than (SA/AV) node.

Answer 18

X = third;
AV;
SA

Question 19

Mobitz type 1 or Wenckebach (X) degree block displays which phenomenon?

Answer 19

X = second

PR intervals increase with each subsequent impulse until one beat (QRS) “dropped” (P not conducted); then rhythm reset and cycle repeats

Question 20

Mobitz type 2 (X) degree block differs from Mobitz type 1 in that:`Which is more common?

Answer 20

X = second

P wave is dropped but is not preceded by complexes with progressively prolonged PR intervals

Type 1 more common

Question 21

EKG: A constant, prolonged QRS, period of ventricular depolarization, can be explained by (X).

Answer 21

X = of conduction in one of the bundle branches

Question 22

In EKG, you see two random odd-shaped QRS complexes, not preceded by P wave. It’s likely that these were triggered spontaneously from a(n) (X) in the (atria/ventricles).

Answer 22

X = irritable focus

Ventricles

Question 23

In EKG, you see two random odd-shaped QRS complexes, not preceded by P wave. If the contours of the two waves are different, it is likely that there were (X) number of (Y) that led to depolarizations travelling along (same/different) routes.

Answer 23

X = at least 2
Y = irritable foci (in ventricles)
Different

Question 24

Ventricular (X) presages sudden cardiac death

Answer 24

X = fibrillation

Question 25

Ventricular (tachycardia/fibrillation) can deteriorate to ventricular (tachycardia/fibrillation).

Answer 25

Tachycardia;

Fibrillation