1. Supraventricular Tachycardia
Teresa Menendez Hood, MD FACC
Presbyterian Hospital of Dallas

2. Supraventricular Tachycardias
AV nodal reentry tachycardia
AV reentry tachycardia - the WPW(Wolff-Parkinson White) Syndrome
Atrial flutter
Atrial Fibrillation
Atrial Tachycardia
Sinus Tachycardia and Sinus Node Reentry

3. Atrial Fibrillation
Unorganized, very rapid electrical foci in the atria
No contraction of the atria as a whole
In order to protect the ventricles, the AV node blocks most of the atrial impulses from conducting through to the ventricles, thus protecting the ventricles
Controlled rate = ventricular rate < 100 beats/min
Uncontrolled rate = ventricular rate > 100 beats/min

4. Atrial Fibrillation Characteristics of atrial fibrillation:
Ventricular rhythm is usually irregularly irregular
Average ventricular rate is 160 – 180 beats/min on no drugs
No P waves seen
QRS interval is usually normal (narrow)
If see discrete P waves…think of MAT
This clinical scenario is a cardiac or pulmonary patient in the ICU. Thought to be due to a hyperadrenergic state and CCB and helpful.

5. Atrial Fibrillation
Control the rate using IV calcium channel blockers or beta-blockers…IV dig does not work
If the A-fib is chronic (> 48 hours)
Chemical cardioversion after a period of anticoagulation
Electrical cardioversion only after anticoagulation

6. Atrial fibrillation accounts for 1/3 of all patient discharges with arrhythmia as principal diagnosis.
6% PSVT
6% PVCs
18% Unspecified
4% Atrial Flutter
9% SSS
34% Atrial Fibrillation
8% Conduction Disease
10% VT
3% SCD
2% VF
Data source: Baily D. J Am Coll Cardiol. 1992;19(3):41A.

7. Classification of Atrial Fibrillation The 3 Ps
Permanent - Conversion to sinus rhythm not possible
Persistent - Capable of being converted to sinus rhythm
Paroxysmal - Converts spontaneously to sinus rhythm
Gallagher MM and Camm AJ Clin Cardiol 1997;20:381

8. AF: Anticoagulation - General Points
AF most common significant rhythm disorder
Prevalence: 1.5%-3% of patients in their 60s 5%-7% of patients in their 70s 15% of patients in their 80s
AF most potent common risk factor for stroke
Relative risk = 5
Patients with AF can be stratified according to risk of stroke
Feinberg WM e al. Arch Intern Med 1995;155:469 Wolf PA et al. Stroke1991;22:983

9. AF: Anticoagulation - General Points
Anticoagulation (INR ) can reduce risk of stroke by 2/3 1,2
Aspirin has little effect on risk of stroke due to AF 3
1 Hylek EM and Singer DE. Arch Intern Med 1994;120:897
2 Hylek EM et al. New Engl J Med 1966;335:540
3 The Atrial Fibrillation Investigators. Arch Intern Med 1997;157:1237
1/98
medslides.com

10. Risk Factors for Stroke in AF
Prior stroke
Age
Hypertension
Diabetes
Relative Risk (multivariate)
2.5
1.4 (per decade)
1.6
1.7
Absolute Risk
Age < 65 years and no risk factors, “lone AF”: 1%/yr.
All others: 3.5%-8+%/yr lowered to ~1.5%/yr by warfarin
The Atrial Fibrillation Investigators Arch Intern Med 1994;154:1449
1/98
medslides.com

11. Elective Cardioversion of AF Anticoagulation
Cardioversion appears to raise risk of embolism
1%-5% emboli within hours to weeks
Anticoagulation well before and after greatly reduces risk
Standard guideline for electrical or drug cardioversion
INR for 3 weeks before; and
INR for 4 weeks after NSR
IF AF < 2 days’ duration, no anticoagulation
Laupacle A et al. Chest 1995;108
Prystowsky EN et al. Circulation 1996;1262

12. Adequate Rate Control At office visits
Apical (not radial) heart rate (sitting):  80 / min
On 24-hour Holter monitor
Goal: average hourly heart rate  80 / min
Exercise testing
Inadequate:  85% age-predicated maximum heart rate in stage I (Bruce) or 3 min of exercise
Digoxin alone will never control the rate unless the patient has intrinsic AVN conduction system disease

13. Tachycardia - Induced Cardiomyopathy
Chronic tachycardia in otherwise structurally normal heart as the sole cause of developing ventricular dysfunction
Can follow any chronic cardiac tachyarrhythmia
Fenelon G et al. Pacing Clinical Electrophysiol 1996;19:95

14. Preference for Acute Cardioversion
DC Cardioversion
i.v. Ibutilide
Other:
Oral Flecainide
Oral Propafenone
i.v. Procainamide

15. Preference for Acute Cardioversion i.v. Ibutilide
QTc  460 msec
Short duration of AF (<30 days)
No clinical CHF. K and Mg levels OK
Anesthesia risk (e.g., COPD)
Patient preference
Acute efficacy - flutter (63%), fib (31%)
Caution: risk of polymorphic VT (8%)
Stambler BS, et al. Circulation 1996; 94:

16. Long term treatment Beyond the scope of this talk
Guided by patient symptoms
AFFIRM trial did not show any benefit of NORMAL SINUS RHYTHM versus AFIB with rate control in patients who had minimal symptoms
Ablation for AFIB is guided by patients’ symptoms and drug failures

17. Atrial Flutter Usually a single, irritable foci in the atria (right)
AV node protects the ventricles by blocking some of the atrial impulses (decremental conduction)
P waves take on a “sawtooth” appearance and are called F waves or flutter waves
Atrial rhythm and ventricular response are usually regular
Atrial rate beats/min. Ventricular rate varies depending on the number of impulses the AV node is blocking
No P waves or PR interval
QRS normal width or with aberrancy

18. Atrial Flutter Treatment:
Same as atrial fibrillation but often harder to slow the ventricular rate
Long term treatment is ablation and NOT drugs!

19. RF Ablation of Atrial Flutter
Atrial flutter involves a macro-reentry circuit within the right atrium.
Critical areas of conduction within the right atrium are necessary to sustain atrial flutter.
RF ablation of conduction within such critical sites (most commonly the inferior vena cava-tricuspid valve isthmus) abolishes atrial flutter in 85% of cases.
Cosio FG. Am J Cardiol. 1993;71:

20. Diagram of Atrial Flutter Circuit Within Right Atrium
Inferior vena cava - tricuspid valve isthmus
Cosio FG. Am J Cardiol. 1993;71:

21. Differential Diagnosis of Wide-Complex TachycardiaVT
SVT with aberrancy (atrial fibrillation/flutter)-i.e. BB Block
Antidromic AV reentry –i.e. antegrade via WPW accessory pathway
Atrial fibrillation, atrial flutter, atrial tachycardia, or AV nodal reentry in setting of WPW with rapid conduction down accessory pathway that is activated as a bystander-I.e. not an integral part of the circuit.

22. Wide QRS - BBB (Aberrant conduction)
Narrow QRS
Wide QRS - BBB (Aberrant conduction)
AVN A B HB RB LB
Wide QRS - Preexcitation (Conduction via AP)
Wide QRS - VT C D
Akhtar M. In:Zipes and Jalife. Cardiac Electrophysiology from Cell to Bedside :636.

23. Key ECG Signs Atrial activity QRS configuration R-R cycle length
Aberrant ventricular conduction
Response to vagal maneuvers

24. An EKG you will see on the Boards………..
This has been on every Board exam I have ever taken. Please do give AVN blockers for this!When in doubt, treat as if you thought this was VT.

25. Atrial Fibrillation with Preexcitation

26. Electrocardiographic Differentiation of VT vs. SVT with Aberrancy
Clinical history – if the patient has had an MI in the past?…it is VT until proven otherwise
AV dissociation
QRS morphology
QRS axis
Fusion beat
Capture beat

27. A-V Dissociation, Fusion, and Capture Beats in VT
ECTOPY
FUSION
CAPTURE
Fisch C. Electrocardiography of Arrhythmias ;134.

28. ECG Distinction of VT from SVT with Aberrancy
Favors VT Favors SVT with Aberrancy
Duration RBBB: QRS > 0.14 sec. < 0.14 sec. LBBB: QRS > 0.16 sec. < 0.16 sec.
Axis QRS axis -90° to ±180° Normal

29. ECG Distinction of VT from SVT with Aberrancy
Favors VT Favors SVT with Aberrancy
Morphology Precordial concordance
If LBBB: V1 duration > 30 ms S wave > 70 ms S wave notched or slurred V6: qR or QR R wave
If RBBB: V1: monophasic R wave qR If triphasic, R > R1 R < R1 V6: R < S

30. Sinus Tachycardia
Sinus node is still the pacemaker, but the rate is accelerated for some physiologic reason:
Rhythm is regular
Rate > 100 beats/minute
P wave, PR interval, and QRS complex are all normal
Can look like Sinus Node Reentry – paroxysmal and less than 160 BPM; incidence of ~10% of all PSVT’s

31. Sinus Tachycardia Treatment:
Alleviate the underlying cause-anemia, pheo, hyperthyroid…
Could be inappropriate ST- a type of autonomic dysfunction with HR consistently above 120

32. Paroxysmal Supraventricular Tachycardia
Repeated episodes of tachycardia with an abrupt onset and ending (paroxysmal)
SVT is usually due to a reentry mechanism.
Could also be to abnormal automaticity or triggered activity but would have more of a warm-up and cool-down effect.

33. Supraventricular Tachycardia
Characteristics:
Rhythm is regular
Rate beats/minute
P waves may be buried in the QRS or the T wave and may differ in morphology from sinus P waves
PR and QRS interval may be normal or prolonged.

34. Supraventricular Tachycardia
Long term treatment is with ablation in most cases
Response to vagal maneuvers is helpful
Acutely: meds used to decrease the rate or convert the patient to NORMAL SINUS RHYTHM: Adenosine, IV Verapamil or Esmolol
If patient is unstable:
Electrical cardioversion

35. Pearls
ST depression is common during SVT and is not a marker of serious ischemia
If the first dose of Adenosine does not work? Then add 6mg to the amount and give again ( )…do not repeat the same dose. (If given via central line then )
Adenosine may put the patient in AFB…be ready to cardiovert.

36. Classification of PSVT
Short R-P
AVRT(slow-fast)
AVNRT
Long R-P
Atypical forms of the AVNRT (fast-slow)or AVRT(usually will have a negative P wave in 2,3,avf)
Most atrial tachycardias, SNRT
PJRT

37. Atrial Tachycardia
Reentry, Automaticity and Triggered (rare) Activity have been found as causes
Rates 120 to 150
Usually 1:1 AVN conduction and persistence despite AV block
Usually from right atria (Ring of Fire)
Can be seen as an incisional tachycardia from previous surgery..i.e. ASD repair
May see remission in children so do not attempt ablation until adulthood.

38. AVN reentry Most common from of PSVT
Can occur at any age and more common in women
Typical form is down the slow and up the fast pathway in the AVN region.
Adenosine is the drug on choice for conversion. Need to be careful about pts with reactive airway disease and those on persantine. It may not work in pts with theophylline.

39. WPW
Pre-excitation affects 3/1000 patients on routine screening….not all develop PSVT
Antegrade (delta wave) and retrograde conduction
More common in men
Most present in young adulthood
15% incidence of AFIB
Multiple pathways in 10%