Approach to Narrow QRS Complex Tachycardia

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🌱 來自: Huppert’s Notes

Approach to Narrow QRS Complex Tachycardia🚧 施工中

Approach to Narrow QRS Complex Tachycardia

•   UNSTABLE: If sinus tachycardia, treat the underlying cause if present (e.g., treat sepsis). If the tachycardia is due to a tachyarrhythmia, perform synchronized cardioversion.

•   STABLE: Try to identify the rhythm (see rhythm abbreviations on the next few pages). Some clues:

-   Regular vs. irregular

-   Onset: Abrupt onset/offset suggests reentrant circuit (SANRT, AVNRT, AVRT)

-   Atrial rate:

•   Sinus tachycardia: typically 100–150 bpm (max rate = 220 – age)

•   Atrial tachycardia: typically 150–250 bpm

•   Atrial flutter: Atrial rate can be up to 300 bpm (ventricular rate often 150 bpm for 2:1 block)

•   Atrial fibrillation: Atrial rate can be 350+ bpm

-   P-wave morphology:

•   ST, SANRT: Sinus P waves

•   AVNRT: No P waves or distorts QRS (pseudo RSR’ in V1)

•   AVRT: Retrograde or buried P waves

•   MAT: ≥3 P-wave morphologies before the QRS

•   Atrial fibrillation: No P waves

•   Atrial flutter: Flutter waves

-   RP intervals: See Figure 1.15

FIGURE 1.15: Interpretation of the RP interval.

•   Short RP: P wave closer to the preceding R wave than the following R wave (i.e., first half of RR)

-   Ddx short RP: Typical AVNRT, antidromic/orthodromic AVRT, junctional tachycardia, atrial tachycardia with marked PR prolongation

•   Long RP: P wave closer to the following R wave than the preceding R wave

-   Ddx long RP: Sinus tachycardia, atypical AVNRT, orthodromic AVRT, atrial tachycardia

-   Response to vagal stimulation or adenosine (can be both diagnostic and therapeutic, see Table 1.8)

TABLE 1.8 • Adenosine Administration

•   AVNRT, AVRT: Terminates arrhythmia, classically with P wave after the last QRS

•   ST, AT, MAT, atrial flutter: Slows ventricular rate enough to reveal an underlying atrial rhythm, but it doesn’t usually terminate it (Exception: AT sometimes terminates with adenosine)