1
Paroxysmal
supraventricular
tachycardia (PSVT)
A clinical syndrome characterized by the presence of a regular
and rapid tachycardia of abrupt onset and termination. ese
features are characteristic of AVNRT or AVRT, and, less
frequently, AT. PSVT represents a subset of SVT.
Atrial fibrillation
(AF)
A supraventricular arrhythmia with uncoordinated atrial
activation and, consequently, ineffective atrial contraction.
ECG characteristics include: 1) irregular atrial activity,
2) absence of distinct P waves, and 3) irregular R-R intervals
(when AV conduction is present). AF is not addressed in this
document.
Sinus tachycardia Rhythm arising from the sinus node in which the rate of
impulses exceeds 100 bpm.
• Physiologic sinus
tachycardia
Appropriate increased sinus rate in response to exercise and
other situations that increase sympathetic tone.
• Inappropriate sinus
tachycardia (IST)
Sinus heart rate >100 bpm at rest, with a mean 24-h heart rate
>90 bpm not due to appropriate physiological responses or
primary causes such as hyperthyroidism or anemia.
Atrial tachycardia (AT)
• Focal AT An SVT arising from a localized atrial site, characterized by
regular, organized atrial activity with discrete P waves and
typically an isoelectric segment between P waves. At times,
irregularity is seen, especially at onset ("warm-up") and
termination ("warm-down"). Atrial mapping reveals a focal
point of origin.
• Sinus node reentry
tachycardia
A specific type of focal AT that is due to microreentry arising
from the sinus node complex, characterized by abrupt onset
and termination, resulting in a P-wave morpholog y that is
indistinguishable from sinus rhythm.
• Multifocal atrial
tachycardia
(MAT)
An irregular SVT characterized by ≥3 distinct P-wave
morphologies and/or patterns of atrial activation at different
rates. e rhythm is always irregular.
Atrial flutter
• Cavotricuspid
isthmus (CTI)–
dependent atrial
flutter: typical
Macroreentrant AT propagating around the tricuspid annulus,
proceeding superiorly along the atrial septum, inferiorly
along the right atrial wall, and through the CTI between the
tricuspid valve annulus and the Eustachian valve and ridge.
is activation sequence produces predominantly negative
"sawtooth" flutter waves on the ECG in leads 2, 3, and aVF and
a late positive deflection in V1. e atrial rate can be
slower than the typical 300 bpm (cycle length 200 ms) in the
presence of antiarrhythmic drugs or scarring. It is also known
as "typical atrial flutter" or "CTI– dependent atrial flutter" or
"counterclockwise atrial flutter."
Table 1. Relevant Terms and Definitions (cont'd)
Arrhythmia/Term Definition
