Cardiovascular Critical Care I
Etiologies of tachyarrhythmias
Usually related to enhanced automaticity, reentry, or triggered activity
A history that includes ischemic heart disease or congestive cardiac failure is 90% predictive of
VT.
Evaluate for the presence of P waves.
Evaluate the width of the QRS complex.
2002;324:1264-7; BMJ 2002;324:1201-4; Circulation 2012;125:381-9; Heart Fail Rev 2014;19:285-93; J Am Coll
Cardiol 2018;72:1677-749)
Supraventricular Tachyarrhythmias
Type
Rhythm
P-wave
Attributes
Atrial Rate
(beats/min)
Description
Premature atrial
complexes
(PACs)
Irregular
N/A
N/A
Generally benign but may be more evident with
increased sympathetic tone, stress, and pericardi-
tis or with sympathomimetic use
In some cases, can lead to an AV block or initiate a
reentrant supraventricular tachycardia (SVT) or AF
Supraventricular
tachycardia
(SVT)
Regular
Hidden
or can be
retrograde
140–250
Usually sudden onset/offset with narrow QRS
complexes
Often caused by reentry within the atrium or AV
node or by an accessory conduction pathway
Can be subcategorized as:
AV nodal reentrant tachycardia (AVNRT)
AV reentrant tachycardia (AVRT)
Sinus node reentry tachycardia
Atrial flutter
(AFl)
Regular
Saw-tooth
appearance
180–350
Generally conducts through the ventricles in a 2:1
fashion, resulting in ventricular rates of 100–150
beats/min
In some scenarios, slowing the atrial rate may
increase the number of conducted beats, leading
to rapid ventricular rates and potential hemody-
namic compromise
Associated with increased risk of stroke
Atrial
fibrillation
(AF)
Irregular
No distinct P
wave visible
Unable to
determine
Most common arrhythmia, characterized by irregu-
lar ECG appearance because of multiple reentry
circuits and ectopic foci (“irregularly irregular”)
Often associated with structural heart disease and
potentiated by increased left atrial pressures
among other influencing contributors such as age,
inflammation, and sympathetic tone
Associated with increased risk of stroke