Supraventricular Tachycardia

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 lt 100
  beats/min
• Uncontrolled rate ventricular rate gt 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 wavesthink 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-blockersIV dig does not work
• If the A-fib is chronic (gt 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.
199219(3)41A.
7
Classification of Atrial FibrillationThe 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 199720381
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 1995155469
Wolf PA et al. Stroke199122983
9
AF Anticoagulation - General Points

• Anticoagulation (INR 2.0 - 3.0) 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
1994120897 2 Hylek EM et al. New Engl J Med
1966335540 3 The Atrial Fibrillation
Investigators. Arch Intern Med 19971571237
10
Risk Factors for Stroke in AF

• Risk Factor
• Prior stroke
• Age
• Hypertension
• Diabetes

• Relative Risk (multivariate)
• 2.5
• 1.4 (per decade)
• 1.6
• 1.7

Absolute Risk Age lt 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 19941541449
11
Elective Cardioversion of AFAnticoagulation

• 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 2 - 3 for 3 weeks before and
• INR 2 - 3 for 4 weeks after NSR
• IF AF lt 2 days duration, no anticoagulation

Laupacle A et al. Chest 1995108 Prystowsky EN et
al. Circulation 19961262
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
19961995
14
Preference for Acute Cardioversion

• DC Cardioversion
• i.v. Ibutilide
• Other
• Oral Flecainide
• Oral Propafenone
• i.v. Procainamide

15
Preference for Acute Cardioversioni.v. Ibutilide

• QTc ? 460 msec
• Short duration of AF (lt30 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 941613-1621
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 250-350 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. 199371705-709.
20
Diagram of Atrial Flutter Circuit Within Right
Atrium
Inferior vena cava - tricuspid valve isthmus
Cosio FG. Am J Cardiol. 199371705-709.
21
Differential Diagnosis ofWide-Complex Tachycardia

• VT
• 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
Narrow QRS
Wide QRS - BBB(Aberrant conduction)
AVN
A
B
HB
RB
LB
Wide QRS - VT
Wide QRS - Preexcitation(Conduction via AP)
C
D
Akhtar M. InZipes and Jalife. Cardiac
Electrophysiology from Cell to Bedside. 1990636.
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
V1
E
F
C
ECTOPY
FUSION
CAPTURE
Fisch C. Electrocardiography of Arrhythmias.
1990134.
28
ECG Distinction of VT from SVT with Aberrancy

• Favors VT Favors SVT with Aberrancy

Duration RBBB QRS gt 0.14 sec. lt 0.14
sec. LBBB QRS gt 0.16 sec. lt 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 gt 30 ms S wave gt 70 ms S wave notched
or slurred V6 qR or QR R wave If
RBBB V1 monophasic R wave qR If triphasic,
R gt R1 R lt R1 V6 R lt S
30
Sinus Tachycardia

• Sinus node is still the pacemaker, but the rate
  is accelerated for some physiologic reason
• Rhythm is regular
• Rate gt 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 PSVTs

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 140-220 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
  (6-12-18)do not repeat the same dose. (If given
  via central line then 3-6-9-12)
• Adenosine may put the patient in AFBbe 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 11 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