What do you find on the EKG of a patient with Paroxysmal Supraventricular Tachycardia

1.

Kalman, Jonathan M., Sanders, Prashanthan (2022). In Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine (pp. 1245). DOI: 10.1016/B978-0-323-72219-3.00065-7

SVT is most classically a regular narrow-complex tachycardia with a wide rate range from just in excess of 100 bpm to over 250 bpm in some patients (Fig. 65.18). In some patients bundle branch aberrancy may be present during tachycardia. This is more commonly right bundle aberrancy due to the longer refractory period of the right bundle compared with the left bundle (Fig 65.18A). Occasionally, patients with SVT may have a preexisting bundle branch block even in sinus rhythm, resulting in a wide complex tachycardia that nevertheless has a typical bundle branch block appearance (Fig. 65.19). In cases of aberrancy, the differential diagnosis may include some forms of VT such as a fascicular VT (Fig. 65.20). The ECG of PSVT can be classified according to the VA relationship (Fig. 65.21). When there are more atrial than ventricular complexesthe possibilities include focal AT (seeFig. 65.5), AV node reentry with block (Fig. 65.22) or AFL (seeFig. 65.11B, C). When there are fewer atrial than ventricular complexes during a narrow-complex tachycardia, the differential diagnosis includes only quite rare entities, including junctional ectopic tachycardia (JET), a concealed nodofascicular pathway and high septal fascicular VT (seeFig. 65.21). Most commonly, when the atrial and ventricular complexes occur 1:1, the tachycardia can be further defined in terms of whether the P wave falls in the first half of the R-R interval (short RP tachycardia) or the second half of the R-R interval (long RP tachycardia).

2.

Supraventricular Tachycardia (SVT), Elsevier ClinicalKey Clinical Overview

Diagnosis Diagnostic ECG findings: Atrial and/or ventricular rate greater than 100 bpm though often the rate exceeds 150 bpm Narrow complex QRS with underlying association of atrial and ventricular activity OR Wide QRS tachycardia with underlying association of atrial and ventricular activity and thus, not consistent with VT (ventricular tachycardia) SVT with a wide QRS may result from: Aberrant conduction Preexisting bundle branch block Ventricular preexcitation, such as that seen in WPW (Wolff-Parkinson-White) The absence of ECG findings consistent with atrial fibrillation or atrial flutter

Basic Information AVNRT can have either of the following: Short RP tachycardia occurs when the R-P interval is less than 50% of R-R interval Long RP tachycardia occurs when the R-P interval is greater than 50% of R-R interval See Figure 3 for ECG demonstrating typical AVNRT AVRT: second most common type of SVT; results from the formation of a reentrant circuit involving the normal AV conduction system and an AV accessory pathway The common (orthodromic) form of AVRT uses the AV node for antegrade conduction and the accessory pathway for retrograde conduction The uncommon (antidromic) form of AVRT uses an accessory pathway for antegrade conduction and the AV node for retrograde conduction AVRT accounts for 30% of SVT cases Key ECG features Regular SVT Typically narrow complex QRS Atrial activity visible Fixed QRS to P wave (R-P) interval Short RP tachycardia occurs when the R-P interval is less than 50% of R-R interval Long RP tachycardia occurs when the R-P interval is greater than 50% of R-R interval See Figure 4 for ECG demonstrating typical AVRT WPW (Wolff-Parkinson-White) syndrome is a constellation of the presence of an accessory pathway and symptoms of arrhythmia AT: typically a focal arrhythmia originating from a location distinct from the sinus node; can also arise from multiple locations in the right or left atria Mechanism may be automatic, triggered, or reentrant Age-related changes to the atrial myocardium and autonomic influences facilitate AT in older adults Accounts for 10% of cases Key ECG features May be irregular P wave may differ from sinus rhythm AV relationship as measured by the PR and RP intervals may vary Ventricular conduction can be variable and the atrioventricular conduction ratio may be higher than 1 to 1

3.

Elsevier ClinicalKey Clinical Overview

Terminology Atrioventricular nodal reentry tachycardia is the most common type of paroxysmal supraventricular tachycardia; it is due to a reentry circuit (via a functionally and anatomically distinct pathway) in or around the atrioventricular node Most common ECG pattern is a narrow QRS complex tachycardia without visible P waves (hidden within the QRS complex) and with a regular RR interval