Supraventricular Arrhythmias
Ira R. Friedlander, M.D.
8/26/14
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
Mechanisms of Arrhythmia
• Automaticity– Enhanced automaticity – Abnormal automaticity
Mechanisms of Arrhythmia
• Triggered Activity– Small depolarizations during or just after
repolarization (phases 3 or 4) which can trigger a new depolarization.
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
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.
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
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
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.
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
Atrial Tachycardia
• Ectopic atrial focus– Reentrant, automatic or
triggered
• 150-250 bpm• 1:1 AV conduction• Paroxysmal or “warm up”• P wave morphology
variable
Focal Atrial TachycardiaFocal Atrial Tachycardia
CSOCSO
IVCIVC
RAFWRAFW
RAARAA LAALAA
LAFWLAFW
PVPV
SNSN
IIA A SS
CTCT
* * ** * *
SVCSVC
20 yr woman with post-partum congestive heart failure20 yr woman with post-partum congestive heart failure
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
Adenosine InjectionAdenosine Injection
III
IIIaVRaVL
aVF
V1
V2
V3
V4
V5V6
I
II
IIIaVR
aVL
aVF
V1
V2
V3
V4
V5V6
Post- Adenosine InjectionPost- Adenosine Injection
Catheter location : Right atrial Catheter location : Right atrial appendageappendage
RAORAO LAOLAO
CT MAP
CS
His
CTMAP
CS
His
IIIII
aVL
I
MAP dist
MAP prox
CT 1,2
CT 5,6
CT 9,10
CT 15,16
CT 3,4
CT 7,8
CT 13,14
CS dist
CS prox
CT 11,12
Earliest Atrial Activation : Right Atrial AppendageEarliest Atrial Activation : Right Atrial Appendage
- 23 msec
IIIII
aVL
I
MAP distMAP prox
CT 1,2
CT 5,6
CT 9,10
CT 15,16
CT 3,4
CT 7,8
CT 13,14
CS distCS prox
CT 11,12
CT 17,18
CT 19,20
Sinus RhythmSinus RhythmAtrial TachycardiaAtrial Tachycardia
RF on 1.9 sec
Atrial Flutter
• Reentrant circuit localized to the RA
• 250-350 bpm
• 2:1 or variable AV block
• Classic “saw-tooth” P waves
Activation on Halo Catheter Activation on Halo Catheter
II
aVF
V1
CS Os
TA 1,2
TA 3,4TA 5,6
TA 7,8
TA 9,10
TA 11,12
TA 13,14
TA 17,18TA 19,20
Typical = CounterclockwiseTypical = Counterclockwise
TA 19,20
CS Os
TA 9,10
TA 1,2
Activation on Halo Catheter Activation on Halo Catheter
Atypical = ClockwiseAtypical = Clockwise
II
aVF
V1
CS Os
TA 1,2
TA 3,4TA 5,6
TA 7,8
TA 9,10
TA 11,12
TA 13,14
TA 17,18 19,20
TA 19,20
CS Os
TA 9,10
TA 1,2
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
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)
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
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)
Drug Therapy to Maintain Sinus Rhythm in Patients with Recurrent Paroxysmal or Persistent Atrial Fibrillation
ACC/AHA/ESC Guidelines
Atrial FibrillationCatheter Ablation
Ablate PV potentials PV Isolation Pappone (circumferential LA ablation)
AV Nodal Reentrant Tachycardia
Morphology and location of P wave relative to QRS distinct
27 y.o with palpitations
Pseudo R’ in V1 during tachycardia
NSR AVNRT
Junctional Ectopic Tachycardia
Normal sinus rhythm
Junctional tachycardia
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)
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)
Orthodromic AVRT
Conduction down AV axis during tachycardia gives NARROW QRS complex
Pre-excited Tachycardia Mechanisms
AVRT AT
AVNRT
Conduction down AP during tachycardia gives WIDE QRS complex
Atrial Fibrillation
RF Ablation in WPW
SUMMARYMechanisms of SVT
Atrial Tachycardia AVNRT AVRT
FPSP
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
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
Top Related