junctional arhythmias

Question 1

what is the AV junction?

Answer 1

AV node and bundle of HIS

Question 2

what are junctional arrhythmias usually caused by?

Answer 2

automaticity or re-entry

Question 3

how does the P wave and QRS appear in junctional arrhythmias ? P interval?

Answer 3

p wave usually appear inverted or oppositely formed from the sinus’ and QRS width is normal

p interval will be < .12 seconds indicating it came from the AV junction and not in the sinus node

Question 4

why is the p wave inverted in junctional arrhythmias?

Answer 4

because the stimulus occurred at the AV junction and gone back up into the atria to depolarize the atria first and has also gone down into the ventricles producing a normal QRS

Question 5

why does the p wave occur before the QRS>? what happens if its after?

Answer 5

because the atria has depolarized first

if its after ventricles depolarize first and then back into the atria in a “retrograde” fashion

Question 6

what are premature junctional contractions/

Answer 6

extra ventricular contractions that originate from an ectopic focus in the AV junction that oct before the next expected beat.

Question 7

what are some ECG clues of premature junctional contractions?

Answer 7

p waves are absent, buried in QRS, opposite deflection of sinus p and interval will be < .12

qrs is usually normal but ay be wide

rhythm is irregular (incomplete pause)

Question 8

what are the possible causes of premature junctional contractions?

Answer 8

can be normal
dig too
inc vagal tone (parasympathetic -n+V, valsalva maneuver, carotid pressure, MI inferior),
inc sympathetic tone (hypoxia, electrolyte imbalance)
excessive dosage of antiarrythmic

Question 9

what are some hemodynamic effects of premature junctional contractions?

Answer 9

asymptomatic

if pt on dig and it is toxic - may lead to serious arrythmias

Question 10

treatment of premature junctional contractions?

Answer 10

treat underlying cause

Question 11

what is a junctional escape?

Answer 11

occurs when there is a delay in an impulse arriving from the SA node and the AV junctional takes over as a back up pacemaker at ar ate of 40-60 bpm

Question 12

clues of junctional escape?

Answer 12

p waves are absent, buried in QRS, opposite deflection of sinus p and interval will be < .12

qrs normal

rhythm regular

Question 13

possible causes of junctional escape?

Answer 13

normal Sinus response when sinus node fails
dig tox
inc vagal tone (N+V, valsalva maneuver, MI, myocardial ischemia)
hypoxia
electrolyte imbalance
dec sympathetic tone (hypothermia, hypothyroidism, beta blocking drugs)
other drugs (anesthesia, morphine, antiarrhythmic drugs)

Question 14

what are the hemodynamic effects of junctional escape?

Answer 14

asymptomatic

symptomatic
-usually if rate is dec or loss of atrial kick
dec SV
dec CO
dec BP (light headedness, dizziness, syncope)

Question 15

treatments for junctional escape?

Answer 15

correct underlying cause
inc heart rate with atropine
pacemaker

Question 16

what is accelerated junctional/junctional tach/paroxysmal junctional tachy?

Answer 16

if rate of the AV junction exceeds 60/min, it is referred to as accelerated. if the rate exceeds 100/min (junctional tacky). when the rate exceeds 160 and the onset is abrupt (paroxysmal junctional tach)

Question 17

what are the clues for accelerated junctional/junctional tach/paroxysmal junctional tachy?

Answer 17

p waves are absent, buried in QRS, opposite deflection of sinus p and interval will be < .12

qrs normal

rhythm regular

Question 18

what are the causes of accelerated junctional/junctional tach/paroxysmal junctional tachy?

Answer 18

inc sympathetic tone - pain/stress/anxiety, hypoxia, myocardial schema/MI
stimulants (coffee/tea, alcohol, nicotine, street drugs), electrolyte abnormalities, dig tox

Question 19

what are some hemodynamic effects of accelerated junctional/junctional tach/paroxysmal junctional tachy?

Answer 19

may be asymptomatic

symptomatic
inc rate
loss of atrial kick
dec SV
dec CO
dec BP (light headedness, dizziness, syncope)

Question 20

treatment of accelerated junctional/junctional tach/paroxysmal junctional tachy?

Answer 20

underlying cause

Question 21

what is a wandering atrial pacemaker?

Answer 21

the focus moves back and forth between the SA node and an ectopic pacemaker in the atria or AV junction resulting in p waves that vary in shape and size

Question 22

what are some clues of wandering atrial pacemakers?

Answer 22

p waves vary in shape and size
QRS rate usually normal
rate slows and picks up so rhythm may be regular

Question 23

cause of wandering atrial pacemaker?

Answer 23

normal phenomenon especially in young and athletic individuals
chronic atrial hypertrophy
vagal effects that vary with respiration

Question 24

hemodynamic effects of wandering atrial pacemaker?

Answer 24

usually asymptomatic or symptomatic if rate slows excessively

Question 25

treatment of wandering atrial pacemaker?

Answer 25

none or atropine if symptomatic