The AHA Guidelines and Scientific Statements Handbook

The AHA Guidelines and Scientifi c Statements Handbook

• Regular and recurrent palpitations with a sudden
  onset and termination are defi ned as paroxysmal
  supraventricular tachycardia (referred to as PSVT).
  Termination by vagal manoeuvres supports a re-
  entrant tachycardia involving AV nodal tissue
  (AV nodal reciprocating tachycardia (AVNRT)
  or atrioventricular reciprocating tachycardia
  (AVRT)).


• Sinus tachycardia is nonparoxysmal and acceler-
  ates and terminates gradually.


• Pauses or dropped beats followed by sensation of
  a strong heart beat support presence of premature
  beats.
  Symptoms vary with the ventricular rate, underlying
  heart disease, duration of SVT, and individual
  patient perceptions. Important for clinical decision
  making is to describe the pattern in terms of the
  number of episodes, duration, frequency, mode of
  onset, and possible triggers.
  Arrhythmias associated with bypass tracts may be
  life-threatening. A resting 12-lead electrocardio-
  gram (ECG) should be recorded.

Diagnostic investigations
Electrocardiogram, to identify:

• Presence of abnormal rhythm.


• Preexcitation.


• Long QT interval.


• Evidence of underlying heart disease (myocardial
  infarction, hypertrophy, bundle branch block).

Additional evaluation

• 24-hour Holter monitoring: for frequent but tran-
  sient symptoms of tachycardias (several episodes per
  week).


• Event loop recorder: for less frequent
  arrhythmias.


• Implantable loop recorders: are used for infre-
  quent symptoms.


• Exercise testing: clear history of exercise-induced
  arrhythmia.


• Transesophageal atrial stimulation: to provoke
  paroxysmal tachyarrhythmias if other measures
  have failed to document an arrhythmia.


• Invasive electrophysiological study:
  
  
  • in patients with a clear history of regular and
    paroxysmal palpitations or disabling symptoms;
    
    
    • in cases with preexcitation on the 12-lead ECG
      and any symptoms of arrhythmia;
    
    
    • in patients with wide QRS tachycardia where
      diagnosis is uncertain. In combination with cath-
      eter ablation for treatment.
      If the arrhythmia is paroxysmal in nature and there
      is no further clue for the arrhythmia mechanism, a
      beta-blocking agent may be prescribed empirically.
      Anti-arrhythmic agents with Class I or Class III
      properties should not be initiated without a
      documented arrhythmia, due to the risk of
      proarrhythmia.
    
    
    
    
  
  
  
  

Patients with documented arrhythmia

Classify the tachycardia as a narrow- or wide QRS

complex tachycardia by measuring the QRS

duration.

Differential diagnosis for narrow QRS complex

tachycardia (QRS duration <120 ms)

These tachycardias are almost always supraventricu-

lar tachycardias (SVT). The relationship of the P-

waves to the ventricular complex gives a clue to the

diagnosis (Fig. 16.1). Responses of narrow QRS

complex tachycardia to adenosine or carotid massage

may aid in the differential diagnosis (Fig 16.2)

[1].

Differential diagnosis for wide QRS-complex

tachycardia (QRS duration ≥120 ms)

The differential diagnosis for wide QRS-complex

tachycardia includes (Fig. 16.3):

• Ventricular tachycardia (VT).


• SVT with bundle-branch block or aberration.


• SVT with anterograde conduction over an acces-
  sory pathway.
  If the QRS-complexes are identical to those during
  sinus rhythm consider either SVT with bundle-
  branch block, or antidromic AVRT. A history of
  myocardial infarction or structural heart disease
  supports VT. Ventricular fusion beats indicate a
  ventricular origin of the tachycardia. Ventricu-
  loatrial dissociation with a ventricular rate
  faster than the atrial rate generally proves the diag-
  nosis of VT, but is present in only 30% of all VTs.
  An analysis of QRS width and QRS confi guration