TACHYDYSRHYTHMIAS Flashcards
DDx
NARROW REGULAR
Sinus Tachycardia
Orthodromic WPW
SVT (AVNRT)
Atrial Flutter 2:1
NARROW IRREGULAR
Multifocal Atrial Tachycardia
Afib
Atrial Flutter with Variable Block
WIDE REGULAR
Antidromic WPW
Monomorphic VT
SVT with Abberancy
Consider hyperkalemia, acidosis, Na channel blockade
QRS > 140 ms is more likely VT
In the abscence of underlying medical causes, assume VT unless proven otherwise
WIDE IRREGULAR OR POLYMORPHIC COMPLEX (BEAT TO BEAT VARIATION IN QRS)
Afib with Aberrancy (MCC)
Polymorphic V Tachor Torsades
WPW with AFib
SINUS TACHYCARDIA
a. Normal sinus P waves and PR intervals, and
b. Atrial rate between 100 and 160
MULTI FOCAL ATRIAL TACHYCARDIA
a. 3 or more differently shaped P waves
b. Changing PP, PR, and RR intervals
c. Atrial rhythm between 100 and 180 beats / min
ATRIAL FLUTTER
a. A regular atrial rate between 250 and 350 beats / min
b. “Saw tooth” flutter waves directed superiorly and best seen in leads II, III, and aVf
c. AV block, usually 2:1, but occasionally greater or irregular
PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIA
a. Regular, rapid rhythm that arises from impulse re-entry OR an ectopic pacemaker ABOVE the level of the bifurcation of the HIS bundle
b. Narrow complex QRS
c. Rate of 100 to 250 beats / min
d. May have retrograde P waves
AV Nodal Re-Entrant Tachycardia (AVNRT) criteria
Rate 140 - 280 / min
Narrow QRS Complexes (unless abarrent conduction, accessory pathway, or rate-related aberrant conduction)
P waves if visible exhibit retrograde conduction with P-wave inversions in leads (II, III, aVF). Can be buried within qrs (MC), visible after, or rarely visible before the QRS.
If occur at the end of the QRS, may appear as a pseudo R’ in V1 or V2; OR pseudo S in leads II, III, aVF
a/w:
Rate related ST depression is a common abnormality. Unknown clinical significance.
QRS alternans
VENTRICULAR TACHYCARDIA
QRS > 120 ms
Rate > 100 bpm
3 or more consecutive depolarizations from a ventricular ectopic pacemaker
Monomorphic Ventricular Tachycardia
Regular, broad complex tachycardia
Uniform very broad QRS complexes (>160 ms) within each lead — each QRS is identical (except for fusion/capture beats)
Other ECG features suggestive of VT:
Absence of RBBB or LBBB morphology
Extreme “Northwest Axis” deviation
AV Dissociation
Fusion Beats
Captures Beats
Josephson’s sign
Brugada’s sign – The distance from the onset of the QRS complex to the nadir of the S-wave is > 100ms
RSR’ complexes with a taller “left rabbit ear”. This is the most specific finding in favour of VT.
Polymorphic Ventricular Tachycardia
No P waves
Rapid irregular rhythm
Rate usually 140 - 180 b/min (up to 300)
Widened QRS >120 ms with inconsistent beat to beat morphology
