Psvt

narrow complex tachycardias are difficult to handle on surface ekg

1. NARROW COMPLEX TACHYCARDIA

2. 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?

3. Initial approach Stable or unstable Wide or narrow Regular or irregular

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

5. Narrow complex tachycardias “SVTs”

6. 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…….

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

8. SVT:IRREGULAR

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

10. 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

11. 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.

12. 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.

13. 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

14. 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.

15. 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

16. NCT NCT can be Irregular Regular Irregular Atrial fibrillation Atrial flutter with variable block MAT

17. 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

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

19. 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 )

20. 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

21. SVT:REGULAR: A:V > 1 ATRIAL FLUTTER

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

23. 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.

24. 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

25. 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)

26. 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

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

28. 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