Its regularity (or lack thereof) and its response to vagal maneuvers. In this regard:
A regularly irregular tachycardia is a sign of bigeminy or trigeminy. But it can also indicate atrial
flutter with variable atrioventricular block (in this case, look for flutter waves in the neck veins) or a
second-degree heart block in which skipped beats occur at regular intervals.
An irregularly irregular tachycardia is most commonly seen in atrial fibrillation. This is
differentiated from frequent premature contractions because the latter may present with occasional
cannon “A” waves
A regularly regular tachycardia can be due to atrial flutter (with constant A-V block), paroxysmal atrial
tachycardia, ventricular tachycardia, and, of course, sinus tachycardia. Response to vagal maneuvers
might be helpful in separating these entities.
A tachycardia that resolves abruptly after either Valsalva’s maneuver or carotid artery massage is a
paroxysmal atrial tachycardia (typically associated with a unique feeling of “pounding in the neck” due
to the simultaneous occurrence of carotid pulsations and cannon “A” waves).
One that only slows down is usually sinus tachycardia.
One that halves in rate is typically atrial flutter.
Ventricular tachycardia is usually unchanged by vagal maneuvers. Ventricular tachycardia, however,
typically presents with findings of atrioventricular dissociation, such as cannon “A” waves, and variable
intensity of S1.
A regularly irregular tachycardia is a sign of bigeminy or trigeminy. But it can also indicate atrial
flutter with variable atrioventricular block (in this case, look for flutter waves in the neck veins) or a
second-degree heart block in which skipped beats occur at regular intervals.
An irregularly irregular tachycardia is most commonly seen in atrial fibrillation. This is
differentiated from frequent premature contractions because the latter may present with occasional
cannon “A” waves
A regularly regular tachycardia can be due to atrial flutter (with constant A-V block), paroxysmal atrial
tachycardia, ventricular tachycardia, and, of course, sinus tachycardia. Response to vagal maneuvers
might be helpful in separating these entities.
A tachycardia that resolves abruptly after either Valsalva’s maneuver or carotid artery massage is a
paroxysmal atrial tachycardia (typically associated with a unique feeling of “pounding in the neck” due
to the simultaneous occurrence of carotid pulsations and cannon “A” waves).
One that only slows down is usually sinus tachycardia.
One that halves in rate is typically atrial flutter.
Ventricular tachycardia is usually unchanged by vagal maneuvers. Ventricular tachycardia, however,
typically presents with findings of atrioventricular dissociation, such as cannon “A” waves, and variable
intensity of S1.