narrow complex tachycardias are difficult to handle on surface ekg

1. NARROW COMPLEX TACHYCARDIA

3. Case scenario
• 71 year old female arrives in ED with
palpitations and dizziness.
• Rhythm strip in your hand but not sure what
exactly strip shows????.
• Do u need to act now?
• How do you work on whats happening?

4. Initial approach
• Stable or unstable
• Wide or narrow
• Regular or irregular

5. First things first
• If unstable
• And tachyarrythmia is cause of instability
• Think cardioversion first and diagnosis second

6. Narrow complex tachycardias “SVTs”

7.  NCT - QRS DURATION LESS THAN 120 ms.
 In general if QRS is narrow the ventricle is being
activated via normal his-purkinjie system
thus origin of tachycardia is supraventicular.
 SVT with concurrent bundle branch block or
intraventricular conduction defect can produce WCT
despite supraventricular origin…….

8. NARROW COMPLEX TACHYCARDIAS:SVT
• REGULAR OR IRREGULAR.
• “P” WAVE OR NO “P” WAVE.
• R-P DISTANCE : LONG OR SHORT

10. SVT:IRREGULAR

11. SVT:IRREGULAR
Irregular undulation of ECG baseline
(coarse/medium/fine)
Irr.irregular ventricular rhythm

12. SVT:IRREGULAR: NO P WAVES:AF
• Multiple causes including electrolyte
disturbanc,structural heart disease,
cardiac surgery,“lone”.
• Atrial rhythm rapid,irregular with low amplitude
fibrillary waves,no isoelectric period.
• Usually a reentrant circuit within the atria: ocasionally
a single ectopic focus suitable for ablation.
• Treat the cause : duration known rate control
DCCV to convert to sinus rhythm

13. SVT:IRREGULAR
Multifocal atrial tachycardia.
Commonly in elderly patient with underlying lung disease also in hypomagnesemia.
3 different “p” wave morphologies.
Varying P-P and R-R intervals.

14. SVT:IRREGULAR:P WAVES VARIABLE : MAT
• Heart rate > 100 bpm (usually 100-150 bpm; may be
as high as 250 bpm).
• Irregularly irregular rhythm with varying PP, PR and
RR intervals.
• At least 3 distinct P-wave morphologies in the same
lead.
• Isoelectric baseline between P-waves (i.e. no flutter
waves).
• Absence of a single dominant atrial pacemaker (i.e.
not just sinus rhythm with frequent PACs).
• Some P waves may be nonconducted ; others may be
aberrantly conducted to the ventricles.

15. • Inverted flutter waves in II, III,aVF with atrial rate ~ 300 bpm
• Positive flutter waves in V1 resembling P waves
• The degree of AV block varies from 2:1 to 4:1
• R-R Interval multiple of p rate

16. SVT:IRREGULAR:P WAVES:ATRIAL FLUTTER
WITH VARIABLE BLOCK
• P waves at 300bpm or close to
• Usually d/t re-entry rhythm localised to rt.atrium
which generates impulses at rate of 300bpm.
• The ventricular rate is frequently 150bpm due to 2:1
block with in av node.
• Ventricular rate may be irregular if the conduction is
variable(i.e: if 2:1 alternating with 3:1/4:1).
• Saw tooth appearance.
• Narrow negative flutter waves in inferior leads.

17. SVT : IRREGULAR: SUMMARY
• NO P WAVES,NO ISOELECTRIC BASELINE = AF.
• VARYING P MORPHOLOGY AND P-R,P-P = MAT
• FLUTTER WAVES SEEN = AFL WITH VARIABLE
BLOCK

18. NCT
• NCT can be
▫ Irregular
▫ Regular
• Irregular
▫ Atrial fibrillation
▫ Atrial flutter with variable block
▫ MAT

20. SVT: REGULAR : LOOK FOR-
• A:V RATIO
• P WAVE MORPHOLOGY
• UPRIGHT OR INVERTED
• R-P DISTANCE
• Ps hiding in QRS , ST , T WAVES
• V1 BEST FOR STUDYING P WAVE

21. A: V ratio
NCTs with A : V ratio >1
• Atrial tachycardia
• Atrial flutter
• Some rare cases of AVNRT with 2 : 1 block,
usually in the His bundle

22. ATRIAL TACHYCARDIA
Atrial rate > 100 bpm.
P wave morphology is abnormal when
compared with sinus P wave due to ectopic
origin.
3 ectopics p waves should be identical
There is usually an abnormal P-wave axis
(e.g. inverted in the inferior leads II, III
and aVF)

23. ATRIAL TACHYCARDIA
• Usually due to single ectopic focus.
• The underlying mechanism can involve reentry,
triggered activity or increased automaticity.
• May be paroxysmal or sustained.
• Multiple causes including digoxin toxicity, atrial
scarring, catecholamine excess, congenital
abnormalities; may be idiopathic.
• Sustained atrial tachycardia may rarely be seen and
can progress to tachycardia-induced
cardiomyopathy

24. SVT:REGULAR: A:V > 1
• ATRIAL FLUTTER

25. • NCTs with A : V ratio = 1
▫ Comprise a large and heterogeneous group
▫ AVNRT
▫ AVRT
▫ AT
▫ Automatic junctional tachycardia.
A: V ratio

26. RP INTERVAL
• The location of the P wave on the ECG is best described
by the RP and PR intervals.
• The tachycardias with short RP intervals have a
reentrant mechanism that utilizes the fast pathway of the
circuit for retrograde conduction.
• This causes the P wave on the ECG to appear closer to
the terminal portion of the preceding QRS than to the
beginning of the following QRS or the P wave is masked
within the preceding QRS complex.
• The long RP tachycardias have either a reentrant
mechanism that utilizes a slow pathway of the circuit for
retrograde conduction or they have an automatic
mechanism.

27. R-P interval in cases with 1 : 1 A: V
ratio
• Absence of a visible P wave:
▫ AVNRT
• NCTs with a short R-P interval (P wave in the first one-third of the R-R
interval):
▫ SLOW FAST AVRT, AVNRT (especially in patients >50 years old)
• Intermediate R-P interval NCTs (P wave in middle one-third of the R-R
interval) :
▫ AVNRT (“slow-slow”) and AT are more common than AVRT
• Long R-P NCTs :
▫ ATs predominate AVNRT is of the less common “fast-slow” variety

29. SHORT RP SVT:A:V 1:1
1. SLOW-FAST AVNRT
• No apparent retrograde p wave:50% psuedo R^
in V1 or psuedo S in inferior leads (RP<70ms)

31. AVNRT: MECHANISM
• If a premature atrial contraction (PAC)arrives while the
fast pathway is still refractory, the electrical impulse will
be directed solely down the slow pathway.
• By the time the premature impulse reaches the end of the
slow pathway, the fast pathway is no longer refractory
hence the impulse is permitted to recycle retrogradely up
the fast pathway.
• This creates a circus movement whereby the impulse
continually cycles around the two pathways, activating the
Bundle of His anterogradely and the atria retrogradely.The
short cycle length is responsible for the rapid heart rate.
• This is the most common type of re-entrant circuit and is
termed Slow-Fast AVNRT

32. SHORT RP SVT:A:V 1:1
• Orthodromic AVRT : 70MS<RP<PR.
• Uncommon: AT with PR prolongation: the presence
of favours AT.

34. LONG RP SVT
1. FAST-SLOW AVNRT (ATYPICAL)
positive p waves in v1 and negative p wavses
in inferior leads.
2.Orthodromic AVRT using slow Aps
(ATYPICAL)
3. AT with normal PR interval.
4.SANRT,INAPPROPRIATE ST