cardiophysiology EKG rhythms... yes, now blocks

Question 1

locations for blocks

Answer 1

• sa node
• av node
• his bundle
• bundle branches
• subdivisions of the left bundle branch

Question 2

what is a hemiblock

Answer 2

block in one of the two subdivisions of the L bundle branch

Question 3

sinus block

Answer 3

SA fils to pace for at least one cycle and then it resumes pacing.
you can see this because the cycle has NO P wave

Question 4

sick sinus syndrome

Answer 4

• sinus bradycardia, but without a normal escape

- sometimes this happens in marathon runners because their parasympathetic system suppresses heart rate at rest

Question 5

bradycardia tachycardia syndrome

Answer 5

patients with sick sinus sydrome get episodes of SVT, mingled with sinus bradycardia

Question 6

first degree AV block

Answer 6

retards AV node conduction, prolonging the PR interaval more than one large square
this is consistant in each cardiac cycle

Question 7

second degree AV block

Answer 7

• allow SOME atrial depolarizaitons to conduct to ventricles (with QRS)
• when the atrial depolarizations are blocked, there are naked P waves without a QRS

Question 8

two types of second degree AV blocks

Answer 8

• occurs in the av node (wenckebach)

- occurs below the AV node (mobitz)

Question 9

secondary wenckeback in EKG

Answer 9

prolongs the PR interval in each cycle until the P wave fails to elicit a QRS

Question 10

secondary Mobitz in EKG

Answer 10

2:1 or 3:1 P to QRS ratio

this is a problem because they get slow ventricular rate and can lose consciousness

Question 11

every mobitz cycle without a ____ has ____, but NEVER a ____

Answer 11

every cycle without a QRS has a regular (ON TIME) P wave. it is NEVER a premature P’ wave

Question 12

on every EKG look for what things

Answer 12

PR interval; P without QRS

Question 13

consistantly increased PR interval

Answer 13

primary AV block

Question 14

progressively increasing PR interval

Answer 14

series of Wenckebach secondary AV block

Question 15

decreased PR interval

Answer 15

in WPW and LGL syndromes

Question 16

two cases where you may have a P without QRS response

Answer 16

secondary AV blocks (both wenckebach and mobitz)

tertiary AV block (has independent atrial and vetnricular rates

Question 17

what is a tertiary AV block - 2 things

Answer 17

• TOTAL BLOCK of supraventricular depolarizations to the ventricles
• automaticity focus escapes to pace the ventricles at its intrinsic rate

Question 18

tertiary AV block with a junctional focus -2

Answer 18

• you get normal (narrow QRS

- ventricular rate 40-60 bpm

Question 19

tertiary AV block with a ventricular focus - 2

Answer 19

• PVC-like QRS

- ventricular rate 20-40 bpm

Question 20

stokes - adams syndrome

Answer 20

ventricular rate is SUUUPPER SSSLLLOOWWW.

watch them because they are probably gonna pass out…. they’ll need airway maintenance

Question 21

what will you see with a bundle branch block? why

Answer 21

you will either see two QRS’s out of phase OR a wide, bumpy QRS its becuase the ventricles aren’t depolarizing simultaneously (sometimes they call the extra R bump “R ‘ “

Question 22

Left bundle branch block

Answer 22

left ventricular depolarization is delayed here so the trace goes up, makes a lower-case u, and comes back down

Question 23

Right bundle branch block

Answer 23

left ventricle depolarizes on time, but the right side is slow. you get an M shape trace, but the middle of the M goes negative