ECG Rhythm Strip Quiz 85: Electrical interventions

Identify the rhythm and describe the electrical interventions associated with each rhythm.

1.

a.    Attempted defibrillation of ventricular fibrillation
b.    Attempted transcutaneous pacing of atrial flutter
c.    Attempted cardioversion of atrial fibrillation
d.    Attempted defibrillation of multifocal atrial tachycardia

2.

a.   Unsuccessful defibrillation of ventricular fibrillation
b.   Successufl cardioversion of atrial fibrillation
c.   External pacing of aystole with good electrical capture
d.   Failure to capture complete heart block

3.  Is this the appropriate electrical intervention for this rhythm?

a.   Yes, synchronized cardioversion is an acceptable intervention for polymorphic VT
b.   Yes, overdrive pacing is being attempted for polymorphic ventricular tachycardia
c.   No,  unsynchronized cardioversion is only appropriate this monomorphic VF
d.   No,  only unsynchronized shocks should be used on this rhythm

4.

a.  This strip shows successful cardioversion of ventricular tachycardia
b.  This strip shows unsuccessful cardioversion of ventricular fibrillation
c.  This strip shows ventricular tachycardia refractory to defibrillation
d.  This strip shows ventricular tachycardia refractory to cardioversion

5.





a.   Ventricular fibrillation has been successfully defibrillated to a profusing heart rhythm
b.   Ventricular fibrillation has been defibrillated to aystole
c.   The patient remains in ventricular fibrillation after a 4th shock
d.   The patient is having a very bad day



6.


a.    Successful cardioversion of atrial flutter to 1st degree block
b.    Successful cardioversion of atrial flutter to complete heart block
c.    Unsuccessful cardioversion of atrial fibrillation to normal sinus rhythm
d.    Unsuccessful cardioversion of ventricular fibrillation to Wenkebach

7.  This rhythm strip demonstrates...

a.   External pacing of complete heart block below the pacing threshold
b.   External pacing of Mobitz II with good electrical capture
c.   External pacing 3rd degree heart block with good mechanical capture
d.   External pacing of Mobitz I above the pacing threshold

8.

a.   Successful cardioversion of supraventricular tachycardia
b.   Successful defibrillation of junctional tachycardia
c.   Successful external pacing of ventricular tachycardia
d.   Successful cardioversion of sinus tachycardia

9.

a.   External pacing with good electrical capture
b.   Synchronous pacing below the pacing threshold
c.   Pacing with good mechanical capture
d.   Asynchronous pacing below the pacing threshold


10.




a.   Cardioversion of polymorphic ventricular tachycardia to NSR
b.   Cardioversion of ventricular fibrillation to NSR
c.   Cardioversion of monomorphic ventricular tachycardia to NSR
d.   Cardioversion of NSR to monofocal ventricular fibrillation



Answers
1.  c.    Attempted cardioversion of atrial fibrillation.   The AHA recommends that atrial fibrillation be cardioverted between 120 and 200 J.   A TEE or echocardiogram study and anticoagulation should be performed to rule out the presence of atrial clots before proceeding.

2.  a.   Unsuccessful defibrillation of ventricular fibrillation.   The ACLS algorithm for pulseless VF/VT calls for immediate defibrillation using 200 J biphasic and 360 J monophasic.  It is reasonable to increase the joule setting on subsequent defibrillation attempts.

3.   d.   No,  only unsynchronized shocks should be used on this rhythm.   When you look at the rhythm strip, you can see that the machine is not synchronizing on all of the R waves.   Therefore, the AHA recommends unsynchronized shocks for polymorphic ventricular tachycardias

4.  d.  This strip show ventricular tachycardia refractory to cardioversion.   A patient with symptomatic ventricular tachycardia should received immediate cardioversion.   The markers on the R waves show that this is an attempted cardioversion attempt rather than an unsynchronized defibrillation attempt.

5.  b.   Ventricular fibrillation has been defibrillated to aystole and d, the patient is having a very bad day.   Defibrillation is not recommended once the patient reaches an asystolic state.  At this point you would give vasoconstrictors and look for reversible causes:  the Hs and Ts.

6.   a.    Successful cardioversion of atrial flutter to 1st degree block.   The AHA recommends that atrial flutter be cardioverted at an initial joule setting of 50 J.  If unsuccessful  it is appropriate to increase the joule setting on subsequent attempts.

7.  a.   External pacing of complete heart block below the pacing threshold.   The 40mA setting on the external pacer is below the pacing threshold.  You can see that there are pacer spikes which are not immediately followed by a QRS complex.  On this patient you would continue to increase you miliamps until electrical capture is achieved.   Once the pacing threshold is obtained, then assess the patient for mechanical capture by palpating a pulse and obtaining a blood pressure.   The pulse rate should match the rate setting on the external pacer.

8.  a.   Successful cardioversion of supraventricular tachycardia.   The AHA recommends that an unstable patient in SVT receive immediate synchronized cardioversion.   A symptomatic patient that remains in SVT after vagal maneuver attempts and medications is also a candidate for synchronized cardioversion.   Expert consultation is recommended for the symptomatic patient who remains in refractory SVT for the following reasons:

Stable patients may await expert consultation because treatment has the potential for harm.
Sequential use of 2 or more drugs may have adverse effects: bradycardia, hypotension, and torsades de pointes
Expert consultation will be needed for long term management


9.  a.   External pacing with good electrical capture.   The demand pacing rate is 100 bpm with a miliamp setting of 155.  A QRS complex follows each pacer spike.   External pacing is painful so consider analgesics and sedation.  As an alternative to external pacing, the AHA also recommends the use of Dopamine, Dobutamine, and Epinephrine infusions.

10.  c.   Cardioversion of monomorphic ventricular tachycardia to NSR.   The lower joule setting and the presence of the synch markers differentiate this from defibrillation.   For synchronized cardioversion, the AHA recommends the following initial joule settings:
·         SVT, Atrial flutter         50-100 J  
·         Stable VT                      100 J 
·         Atrial fibrillation           120-200 J 
·         Polymorphic VT           200 J (unsynchronized) 

In contrast, the  initial joule for early defibrillation is 200 J biphasic and 360 monophasic.


Reviewed 6/4/13

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