Supraventricular Arrhythmias

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Supraventricular Arrhythmias

• Mohamed Hamdan, MD
• Professor of Internal Medicine
• Director, Clinical Cardiac Electrophysiology

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Definition

• Rapid heart rhythm during which the electrical
  impulse propagates down the normal His Purkinje
  system similar to normal sinus rhythm
• Distinct from ventricular tachycardia which only
  originates in the ventricles

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Mechanisms of Arrhythmia

• Automaticity
• Enhanced automaticity
• Abnormal automaticity

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Mechanisms of Arrhythmia

• Triggered Activity
• Small depolarizations during or just after
  repolarization (phases 3 or 4) which can trigger
  a new depolarization.

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Mechanisms of Arrhythmia

• Reentry-most common mechanism
• Short circuit that forms between two pathways
  that are either anatomically or functionally
  distinct
• Typically
• Path 1 Slow conduction, short refractory period
• Path 2 Rapid conduction, long refractory period

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Reentry
Panel A Most impulses conduct down both pathways.
Panel B Unidirectional block, due to longer
refractoriness in one pathway.
Panel C Potential to have reentry back up the
previously refractory pathway
Panel D Reentry then can persist.
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Supraventricular Arrhythmias

• Atrial arrhythmias (AT, AFL and AF)
• Atrioventricular nodal reentrant tachycardia
  (AVNRT) and junctional ectopic tachycardia (JET)
• Atrioventricular reentrant tachycardia (AVRT)
• Wolf-Parkinson-White Syndrome
• Orthodromic AVRT
• Antidromic AVRT

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SVT Symptoms

• May be variable
• Palpitations, chest pounding, neck pounding
• Weakness/malaise
• Dyspnea
• Chest pain
• Lightheadedness
• Near syncope/syncope
• Symptoms usually abrupt in onset and termination
• May have history of symptoms since childhood or
  have a positive FHx

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SVT Physical Exam

• In absence of tachycardia, usually normal
• Rapid heart rate (150-250)
• May be irregular or regular (mechanism)
• BP may be low or with narrow pulse pressure
• Neck veins may reveal cannon waves.

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Supraventricular Arrhythmias

• Atrial arrhythmias (AT, AFL and AF)
• Atrioventricular nodal reentrant tachycardia
  (AVNRT) and junctional ectopic tachycardia (JET)
• Atrioventricular reentrant tachycardia (AVRT)
• Wolf-Parkinson-White Syndrome
• Orthodromic AVRT
• Antidromic AVRT

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Sinus Rhythm

• Originates in sinus node (automaticity)
• 50-100 bpm resting
• Up to 200 bpm
• Conduction through normal AV axis
• P wave morphology reflects site of onset

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Atrial Tachycardia

• Ectopic atrial focus
• Reentrant, automatic or triggered
• 150-250 bpm
• 11 AV conduction
• Paroxysmal or warm up
• P wave morphology variable

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(No Transcript)
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20 yr woman with post-partum congestive heart
failure
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Adenosine Injection
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Post- Adenosine Injection
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Catheter location Right atrial appendage
LAO
RAO
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Earliest Atrial Activation Right Atrial
Appendage
- 23 msec
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Atrial Tachycardia
Sinus Rhythm
RF on
1.9 sec
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-38 ms
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II
III
V1
V6
RA
Atrial Tachycardia
Sinus Rhythm
RF On
ABL
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Atrial Flutter

• Reentrant circuit localized to the RA
• 250-350 bpm
• 21 or variable AV block
• Classic saw-tooth P waves

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Typical Counterclockwise
V1
II
aVF
TA 19,20
TA 1,2
TA 9,10
TA 3,4
TA 5,6
TA 7,8
TA 9,10
CS Os
TA 1,2
TA 11,12
TA 13,14
TA 17,18
TA 19,20
CS Os
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Atypical Clockwise
TA 19,20
TA 9,10
CS Os
TA 1,2
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Atrial Fibrillation

• Chaotic atrial rhythm due to multiple reentrant
  wavelets
• 350-500 bpm
• Ventricular rate irregular and rapid due to
  variable AV block
• HTN, valvular dz., metabolic dz., CMP, EtOH

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Atrial Fibrillation

• The rapid atrial activity results in
• Increased risk of thrombus formation and stroke
• Rapid and irregular ventricular rate
• The treatment is aimed at
• Decreasing the risk of stroke (coumadin, ASA)
• Decreasing the ventricular rate (beta-blockers,
  calcium channel blockers, digoxin)
• Restoring the rhythm to sinus (drug therapy,
  catheter ablation, surgical Maze)

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Atrial Fibrillation

• Advantages of rhythm control
• Abolition of symptoms
• Halting atrial enlargement
• Improvement in left ventricular function and
  exercise capacity
• Disadvantages of rhythm control
• Subjecting patients to drug therapy and/or
  procedure that might be associated with
  complications

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Atrial FibrillationTreatment

• In patients with minimal symptoms and normal left
  ventricular function
• Coumadin/ASA
• Rate control (drugs, AVJ ablation BV pacing)
• In patients with significant symptoms and/or left
  ventricular dysfunction
• Coumadin/ASA
• Rate control (drugs, AVJ ablation BV pacing)
• Rhythm control (anti-arrhytmic drugs, catheter
  ablation)

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Drug Therapy to Maintain Sinus Rhythm in Patients
with Recurrent Paroxysmal or Persistent Atrial
Fibrillation ACC/AHA/ESC Guidelines
Heart Disease
No (or minimal)
Yes
Heart Failure
CAD
Hypertension
FlecainidePropafenoneSotalol
LVH greater than or equal to 1.4 cm
Sotalol
Amiodarone Dofetilide
Amiodarone Dofetilide
Yes
No
Amiodarone, Dofetilide
Flecainide Propafenone
Disopyramide Procainamide Quinidine
Considernonpharmacologicaloptions
Disopyramide Procainamide Quinidine
Amiodarone Dofetilide Sotalol
Amiodarone
Fuster et al. J Am Coll Cardiol.
2001381231-1265.
Disopyramide, Procainamide, Quinidine
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Atrial FibrillationCatheter Ablation
Ablate PV potentials PV Isolation
Pappone
(circumferential LA ablation)
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Supraventricular Arrhythmias

• Atrial arrhythmias (AT, AFL and AF)
• Atrioventricular nodal reentrant tachycardia
  (AVNRT) and junctional ectopic tachycardia (JET)
• Wolf-Parkinson-White Syndrome
• Orthodromic AVRT
• Antidromic AVRT
• Atrial fibrillation with preexcitation

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AV Nodal Reentrant Tachycardia
Morphology and location of P wave relative to QRS
distinct
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27 y.o with palpitations
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Pseudo R in V1 during tachycardia
NSR
AVNRT
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Junctional Ectopic Tachycardia
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Normal sinus rhythm
Junctional tachycardia
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Supraventricular Arrhythmias

• Atrial arrhythmias (AT, AFL and AF)
• Atrioventricular nodal reentrant tachycardia
  (AVNRT) and junctional ectopic tachycardia (JET)
• Atrioventricular reentrant tachycardia (AVRT)
• Wolf-Parkinson-White Syndrome
• Orthodromic AVRT
• Antidromic AVRT

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Wolff-Parkinson-White Syndrome

• Second electrical connection exists between the
  atria and ventricles (accessory pathway)
• Resemble atrial tissue
• Results in a short PR and
• Delta wave (pre-excitation)
• Some AP conducts only retrograde (concealed)

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Arrythmias in WPW

• The most common arrhythmia is orthodromic AV
  reentrant tachycardia (narrow QRS)
• Less common are pre-excited tachcyardias (wide
  QRS)
• Antidromic AV reentrant tachycardia
• Atrial tachycardia/flutter with pre-excitation
• AVNRT with pre-excitation
• Atrial fibrillation with pre-excitation (most
  life threatening due to rapid ventricular
  response)

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Orthodromic AVRT
Conduction down AV axis during tachycardia gives
NARROW QRS complex
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Pre-excited Tachycardia Mechanisms
AT
AVRT
AVNRT
Conduction down AP during tachycardia gives WIDE
QRS complex
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Atrial Fibrillation
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RF Ablation in WPW
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Supraventricular Arrhythmias

• Atrial arrhythmias (AT, AFL and AF)
• Atrioventricular nodal reentrant tachycardia
  (AVNRT) and junctional ectopic tachycardia (JET)
• Atrioventricular reentrant tachycardia (AVRT)
• Wolf-Parkinson-White Syndrome
• Orthodromic AVRT
• Antidromic AVRT

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SUMMARY Mechanisms of SVT
FP
SP
AVNRT
Atrial Tachycardia
AVRT
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Differential Diagnosis of NCT

• Short RP
• AVRT
• AT
• Slow-Slow AVNRT

• Long RP
• AT
• Atypical AVNRT
• PJRT

• P buried in QRS
• Typical AVNRT
• AT
• JET

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SUMMARY

• Obtain a 12 lead ECG. The location of the P wave
  will dictate the differential diagnosis
• If hemodynamically unstable (chest pain, heart
  failure, hypotension) CARDIOVERSION
• If hemodynamically stable AV NODAL AGENT
• Long term therapy depends on mechanism and can be
  conservative, pharmacologic or invasive
• EP study often needed for definitive
  characterization of mechanism and can cure most
  SVTs with 90 success rate