B4.017 Prework 1 Labeling an Abnormal Rhythm

Question 1

what is a conduction block

Answer 1

delay in normal propagation of depolarizing myocardium

Question 2

normal atrial conduction velocity

Answer 2

PR interval
time between start of SA node and AV node firing, this occurs due to a “pause” effect of the AV node
time = 0.2 s, 200 mS, 5 small boxes

Question 3

normal ventricular depolarization velocity

Answer 3

QRS interval
time to depolarize all of the ventricular myocardium
time = 0.12s, 120 mS, 3 small boxes

Question 4

normal ventricular repolarization velocity

Answer 4

QT interval
time to repolarize all of the ventricular myocardium
time = 0.44 s, should shorten with tachycardia

Question 5

features of a 1st degree AV block

Answer 5

regular rate and rhythm, doesn’t change over the course of the strip
long PR segment (more than 5 small boxes)
can be caused by antiarrhythmics or ischemic heart disease

Question 6

features of 2nd degree AV block: Mobitz type 1

Answer 6

PR interval progressively longer, followed by a nonconducting P wave (not followed by a QRS)
low grade
treated medically
usually no worsening

Question 7

features of 2nd degree AV block: Mobitz type 2

Answer 7

consistent PR intervals, followed by a nonconducting P wave
can advance to unstable rhythm
can lead to heart failure
pacemaker candidate

Question 8

features of a “complete” or 3rd degree AV block

Answer 8

dissociation between electrical activity of atria and ventricles
both regular, but not in relation with one another
unstable conduction block
need pacemaker
can cause bradycardia

Question 9

asystole

Answer 9

no electrical activity
check leads
check gain

Question 10

some causes of sinus tachycardia

Answer 10

anemia
anxiety
infection
exercise
hypoxemia
etc

Question 11

what are supraventricular tachycardias?

Answer 11

originate above the AV node

-narrow QRS, so you know they don’t originate in ventricles

Question 12

features of atrial flutter

Answer 12

cyclical depolarization wave in atria

sawtooth baseline pattern

Question 13

features of atrial fibrillation

Answer 13

more common than atrial flutter
irregularly irregular R-R interval (pulse)
increases incidence of thromboembolic stroke
require blood thinner therapy

Question 14

if you can’t determine the cause of a supraventricular tachycardia, how can you possibly get more clues?

Answer 14

give adenosine
slows conduction through AV node
helps you get a better look at the rhythm on ECG

Question 15

features of monomorphic ventricular tachycardia

Answer 15

QRS wider than 120 mS

• depolarization wave through ventricle moves outside of the normal His/Purkinje system of conductance
• originated in ventricle, likely from the same place since all regular and look the same

Question 16

features of polymorphic ventricular tachycardias

Answer 16

QRS variable shapes and sizes

Question 17

features of ventricular fibrillation

Answer 17

nonperfusing rhythm
cardiac collapse
no pulse

Question 18

features of torsades de Pointes

Answer 18

twists around 3D plane
can be caused by meds that prolong QT interval
can degrade into v-fib or asystole