Classification Of Nsvt

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NSVT can be categorized by morphology, clinical presentation, underlying substrate, and symptoms.

Morphology

Nonsustained tachycardias may present many appearances. The possibility that a nonsustained wide-complex tachycardia may be caused by supraventricular tachycardia with aberrancy should also be considered (see Fig. 2B). Multiple algorithms have been proposed to aid in diagnosis; from a practical perspective, wide-complex tachycardia is more likely VT than SVT with aberrancy, particularly in patients with structural heart disease. In addition, motion or tremor artifact can occasionally "masquerade" as

Waves With Wide Complex

Fig. 2. Diagnosis of nonsustained wide-complex tachycardia:

(A) Nonsustained wide-complex tachycardia in a patient with remote MI. Although the tachycardia is relatively narrow and somewhat irregular, dissociated P waves are evident in the lower rhythm strip, making the diagnosis nonsustained VT. Note that this was misdiagnosed as SVT with aberrancy.

(B) Two separate rhythm steps of nonsustained wide-complex tachycardia in a patient 48 hours into MI, with RBBB at baseline. During tachycardia, the QRS complex is slightly wider than at baseline. The tachycardia was initiated by a PAC, and is supraventricular in nature.

(C) On this Holter monitor, the baseline rhythm is sinus with frequent PAC's. Note that during the wide-complex tachycardia there is a narrow complex capture beat, making the tachycardia diagnosis NSVT.

Fig. 2. Diagnosis of nonsustained wide-complex tachycardia:

(A) Nonsustained wide-complex tachycardia in a patient with remote MI. Although the tachycardia is relatively narrow and somewhat irregular, dissociated P waves are evident in the lower rhythm strip, making the diagnosis nonsustained VT. Note that this was misdiagnosed as SVT with aberrancy.

(B) Two separate rhythm steps of nonsustained wide-complex tachycardia in a patient 48 hours into MI, with RBBB at baseline. During tachycardia, the QRS complex is slightly wider than at baseline. The tachycardia was initiated by a PAC, and is supraventricular in nature.

(C) On this Holter monitor, the baseline rhythm is sinus with frequent PAC's. Note that during the wide-complex tachycardia there is a narrow complex capture beat, making the tachycardia diagnosis NSVT.

Capture Beat

Fig. 2. (Continued) Diagnosis of nonsustained wide-complex tachycardia:

(D) An irregular, mostly wide-complex tachycardia. Note the variable QRS width, as well as several narrow beats. This is pre-excited atrial fibrillation (AF) in a young patient with Wolff-Parkinson-White Syndrome (WPW).

(E) Tremor artifact on inpatient telemetry misdiagnosed as NSVT. Note that the narrow QRS complexes march through the "wide-complex tachycardia" at a rate of about 100 BPM.

Fig. 2. (Continued) Diagnosis of nonsustained wide-complex tachycardia:

(D) An irregular, mostly wide-complex tachycardia. Note the variable QRS width, as well as several narrow beats. This is pre-excited atrial fibrillation (AF) in a young patient with Wolff-Parkinson-White Syndrome (WPW).

(E) Tremor artifact on inpatient telemetry misdiagnosed as NSVT. Note that the narrow QRS complexes march through the "wide-complex tachycardia" at a rate of about 100 BPM.

wide-complex tachycardia (see Fig. 2E). The electrocardiographic tracing must be inspected carefully to ascertain the diagnosis. The rate and the regularity of the rhythm does not necessarily help in the diagnosis, since NSVT may be irregular and mono-morphic, irregular and polymorphic, apparently polymorphic (beat-to-beat changes resulting from capture and fusion beats), fast, or relatively slow (see Figs. 3A-3K).

Monomorphic NSVT

Monomorphic NSVT originates from a single focal source or single reentrant circuit (see Figs. 2A,3A,3B,3H,3I,3K). A focal source can be caused by enhanced automaticity, or triggered activity caused by delayed after-depolarizations (DADs) or early after-depolarizations (EADs). Chung and Pogwizd, using a 3-dimensional mapping technique, evaluated the mechanisms of NSVT and compared the initiation of nonsustained tachycardia with sustained VT in the same patients (24,25). The mechanisms of NSVT and sustained VT were different. NSVT was initiated from discordant sites caused by either a macro-reentrant or a focal mechanism. Monomorphic VT can present as a single morphology or as multiple morphologies. Multiple monomorphic morphologies may

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Responses

  • elen
    Is nsvt fast or slow beats?
    7 years ago

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