Other Tachycardias
Other Tachycardia Rhythms
There are several other tachycardia rhythms that can be seen with both stable and unstable tachycardia. These rhythms include monomorphic ventricular tachycardia and polymorphic ventricular tachycardia both of which are wide-complex tachycardias.
Wide complex tachycardias are defined as a QRS of ≥ 0.12 second. Expert consultation should be considered with these rhythms.
These wide-complex tachycardias are the most common forms of tachycardia that will deteriorate to ventricular fibrillation.
Monomorphic Ventricular Tachycardia
With monomorphic VT all of the QRS waves will be symmetrical. Each ventricular impulse is being generated from the same place in the ventricles thus all of the QRS waves look the same.
Treatment of monomorphic VT is dependent upon whether the patient is stable or unstable. Expert consultation is always advised, and if unstable, the ACLS tachycardia algorithm should be followed.
Polymorphic Ventricular Tachycardia
With polymorphic ventricular tachycardia, the QRS waves will not be symmetrical. This is because each ventricular impulse can be generated from a different location. On the rhythm strip, the QRS might be somewhat taller or wider.
One commonly seen type of polymorphic ventricular tachycardia is torsades de pointes. Torsades and other polymorphic VT are advanced rhythms which require additional expertise and expert consultation is advised.
If polymorphic VT is stable the ACLS tachycardia algorithm should be used to treat the patient. Unstable polymorphic ventricular tachycardia is treated with unsynchronized shocks (defibrillation). Defibrillation is used because synchronization is not possible.
These wide complex tachycardias tend to originate in the ventricles rather than like a normal rhythm which originates in the atria.
Regarding the term ‘VT’ – how do you differentiate VT rhythm and polymorphic VT rhythm when looking for a few seconds on the monitor?
Actually VT is a general term. Polymorphic VT and Monomorphic VT would both fall in the category of VT and in particular will be seen with pulseless VT. If you look at this link it explains the difference and gives a couple of rhythm strip examples.
Kind regards,
Jeff
Jeff,
I understand that Mg is the drug of choice in polymorphic v-tach if the q-t interval is prolonged.
I do not see a q-t interval. Do you need to see the rhythm prior to the tachy-dysrrhymia?
Yes. you need to see the rhythm prior to torsades. If a patient is on telemetry, the QT interval should be be measured at least once per shift. The QT interval is dependent on the heart rate and must correct based on the heart rate using the following formula.
1. Bazett HC. An analysis of the time relationships of electrocardiograms. Heart. 1920;7:355-70.
RRInterval = 60 / HeartRate
QTICorrected = QTInterval / sqr(RRInterval)
Kind regards,
Chris Jack
2 questions:
1) What sort of a pulse would you be feeling with a polymorphic vt ?
2) Which tachycardias would you use a amioderone infusion?
Thanks
1.)You may feel a weak pulse or a strong pulse depending on how long the polymorphic VT has been going on. One thing is for sure….You won’t be feeling a pulse for very long if this rhythm continues.
2.)You will use the amiodarone for pulseless VT/VF, and other recurrent hemodynamically unstable VT (monomorphic or polymorphic); probably won’t use it on narrow complex tachycardias.
Kind regards,
Jeff
When would see torsades? with pulse w/o pulse . Magnesium would be your drug of choice if QT was prolonged. How would you give Mg with pulse w/o pulse? (dose, time and dilution) Thanks
Common causes for torsades de pointes include diarrhea, hypomagnesemia and hypokalemia. It is commonly seen in malnourished individuals and chronic alcoholics.
Correct, magnesium would be your drug of choice if the QT is prolonged.
For torsades de pointes with cardiac arrest, give 1 to 2 g of MgSO4 IV push over 5 to 20 minutes. If torsades de pointes is intermittent and not associated with arrest, administer the magnesium over 5 to 60 minutes IV. If seizures are present, give 2 g IV MgSO4 over 10 minutes. Administration of calcium is usually appropriate because most patients with hypomagnesemia are also hypocalcemic.
Kind regards,
Jeff
With a pt in polymorphic v tach who is stable and experiencing long periods of this ( 12 seconds and longer) who states he “feels ok” what is the best first and second course of action?
1. Get a crash cart next to him with the defibrillator attached.
2. Consult a cardiologist ASAP
(ECG, O2, Labs esp. metabolic panel, and all of the routine stuff would be good also)
Kind regards,
Jeff
AGAIN THANK YOU SO MUCH!!
wow evergrowing website.i would like to become a member.I am an RN and craving to work for cardiology unit and like to get a. handy(really small) ecg book in the pocket for reference
This site has been more helpful to me than anything I have ever studied! Thank you!
Agreed!
Totally Agree. Lynda
I love this site! I have been ACLS certified for many years but I have to start studying at least one month prior. I work in an outpatient setting and do not have the opportunity to even see rhythms anymore. I hate reading the book every 2 years. I am going to use everything on your site. In what order do you suggest I begin this endeavor? Thanks, Old but not dead yet.
Here is a link to the “study guide” for the site. Hope it helps. Kind regards, Jeff
For Monomorphic VT would that pt be stable? what do you do for stable pt. Loving the site thanks so much!!!!
Monomorphic VT can be stable or unstable. It would depend on the patients signs and symptoms.
Treatment for both stable and unstable tachycardia can be found on this page:
Click where it says “Tachycardia Algorithm Diagram” and you can look at a flowchart that shows interventions.
Kind regards,
Jeff
Fantastic site for people who can speak english and can also read and understand english. Well worth every penny is costs. Thank you guys from all who have gained so much from this entire experience!
Hi Jeff,
What is the difference between cardioversion, defibrillation, and synchronization?
Thanks,
Beth
This web page, “synchronized vs. unsynchronized cardioversion“, covers your question.
As a physician working on a rapid response team I could say this is the best acls review website ever. Keep up the good work guys!!
I know that I will be well prepared for my ACLS exam great learning environment
This site is so helpful and comprehensive, really great site.