Pathologies

Question 1

Sinus tachycardia

Answer 1

> 100 bpm

Due to sympathetic stimulation, hypoxia

Question 2

Sinus bradycardia

Answer 2

<60 bpm

Due to parasympathetic stimulation, high CV fitness

Question 3

Sinus arrhythmia

Answer 3

Regularly irregular rhythm associated with changes in vagal tone due to inspiration and expiration (increase, decrease in rate respectively)

Question 4

Sinus arrest

Answer 4

Pause in rhythm that is not a multiple of the sinus interval.
Due to failure of pacemaker cells.

Question 5

Wandering pacemaker

Answer 5

Irregular rate with variable P-waves due to altering site of pacemaker
Due to inflamed atria or digitalis toxicity

Question 6

Premature atrial contraction

Answer 6

P-wave appears different from normal since it arises from an ectopic pacemaker.
Ectopic beats may have a different P-R interval than sinus beats.
Normal; sometimes caused by alcohol, smoking, caffeine

Question 7

Paroxysmal atrial tachycardia

Answer 7

140-220 bpm
P-wave may be obscured by previous T-waves
May be caused by excess caffeine, smoking, alcohol

Question 8

Atrial flutter

Answer 8

Atrial rate ~300 bpm
Saw-tooth P-wave pattern
Due to atrial macro-reentry

Question 9

Atrial fibrillation

Answer 9

Atrial rate >400 bpm
P-wave not discernable due to high rate
Irregularly irregular rhythm
Due to atrial micro-reentry

Question 10

A-V nodal (Junctional rhythm)

Answer 10

Inverted P-wave either before, during, or after QRS
“Cannon” a-waves if atria contract during/after ventricular contraction
Regular rhythm (distinguishes this from AFIB)
Due to SA node failure and AV node retrogradely conducting to atria.

Question 11

Premature ventricular contractions (PVC)

Answer 11

Wide QRS without preceding P-wave
Different shapes indicate different ectopic sites of origination
Due to ectopic ventricular conduction sources

Question 12

Bigeminy

Answer 12

PVC follows every normal QRS

Question 13

Ventricular tachycardia

Answer 13

Sudden rapid ventricular beat

Usually due to PVC in the vulnerable period (depolarization during normal T-wave) causing macro-reentry

Question 14

Torsade de pointes

Answer 14

Polymorphic ventricular tachycardia

Due to low potassium, long-QT syndrome

Question 15

Ventricular fibrillation

Answer 15

Due to micro-reentry

Defibrillator needed to simultaneously depolarize all tissue and “reset” the heart

Question 16

1st degree A-V block

Answer 16

Long P-R interval

Question 17

2nd degree A-V block

Answer 17

P-R interval lengthens until a QRS is dropped, then repeats cycle
OR
QRS periodically drops without warning

Question 18

3rd degree A-V block

Answer 18

Ventricles and atria beat at unrelated rates

Question 19

Signs of myocardial infarction

Answer 19

Hyperacute T-wave, (Hyperkalemia if present in all leads)
ST-elevation
Early/delayed Q-wave
T-wave inversion

Question 20

Wolff-Parkinson-White syndrome

Answer 20

Short P-R interval

Pre-excitation wave before QRS

Question 21

Lown-Ganong-Levine syndrome

Answer 21

Short P-R

Normal width QRS

Question 22

Causes of abnormally increased voltages

Answer 22

Ventricular hypertrophy due to hypertension, stenosis

Question 23

Causes of abnormally decreased voltages

Answer 23

Decreased muscle mass (old MI), pericarditis, emphysema