Tachycardia
Understanding Tachycardia
SVT: symptomatic / asymptomatic - wide Complex or not - Narrow Complex - regular or not - Heart Rate - Then Rapidity of onset - presence or absence of P-Wave - response to vagal maneuvers and adenosine (if given) - most likely etiology -- your plan
  Bhargava - CCF: Expert Approach to SVT   Bhargava - CCF: Expert Approach to SVT   Reference below is from uptodate RP relationship — In patients with a retrograde P wave, the temporal relationship between the P wave and the R wave divides narrow complex tachycardias into two categories: short RP and long RP tachycardias. Short RP tachycardias — If the RP interval is less than one-half of the RR interval, the tachycardia is considered a short RP tachycardia. The differential diagnosis of a short RP tachycardia is generated by considering the P wave morphology. ●Abnormal P wave – The combination of abnormal P waves and a short RP interval is most often seen in the setting of an atrial tachycardia with AV nodal conduction delay. ●Retrograde P wave – The combination of retrograde P waves and a short RP interval is typical of the "common" form of AVNRT and of AVRT utilizing an accessory pathway. In the "common" form of AVNRT (which accounts for 90 percent of AVNRT), reentry occurs in the AV node and perinodal tissues. Antegrade conduction occurs down the slow pathway and retrograde conduction up the fast pathway. This slow-fast pattern gives rise to retrograde P waves that may be inapparent if obscured by the QRS complex AVRT utilizing an accessory pathway can be either orthodromic or antidromic. Orthodromic AVRT is more common, and in this form of the arrhythmia, antegrade conduction occurs through the AV node, producing a narrow QRS complex, and retrograde conduction to the atrium occurs over an AV bypass tract In contrast, during antidromic AVRT, antegrade conduction occurs through the AV bypass tract and retrograde conduction occurs through the AV node or a second accessory pathway. This pattern of activation results in a wide QRS complex (thus, antidromic AVRT is not a narrow QRS complex tachycardia) Long RP tachycardias — If the RP interval is more than one-half of the RR interval, the tachycardia is considered a long RP tachycardia. As with short RP tachycardias, the differential diagnosis is generated by combining the PR relationship with the P wave morphology. ●Retrograde P waves – The combination of retrograde P waves and a long RP interval is usually caused by either "atypical" AVNRT or by AVRT with a slowly conducting accessory pathway; this combination can also be seen in atrial tachycardia with a focus that is close to the AV node ●Abnormal P waves – The combination of abnormal P wave morphology and a long RP interval usually suggests some form of atrial tachycardia. However, this pattern can also occur in the atypical or uncommon form of AVNRT and in AVRT with a slowly conducting accessory pathway (also called "permanent junctional reciprocating tachycardia" or PJRT) The atypical form of AVNRT, which accounts for 10 percent of AVNRT, is characterized by antegrade conduction down a fast pathway and retrograde conduction through a slow pathway. As a result, the P wave occurs very late in the cardiac cycle (positioning it near to the next QRS complex) In AVRT with a slowly conducting accessory pathway (also called "permanent junctional reciprocating tachycardia" or PJRT), antegrade conduction probably occurs through the AV node, and retrograde conduction through a slowly conducting accessory pathway Because of slow conduction through the retrograde limb of the circuit, the retrograde P wave occurs late in the cardiac cycle. Reference above is from uptodate NARROW COMPLEX TACHYCARDIA (QRS <120 ms; HR > 100 bpm)
Pathophysiological Classification. Understanding this is Important in selecting treatment mechanism
Involving SA Node
Involving Atrium
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