Diagnostic criteria of atrial standstill

  Absent P waves both on surface and intracardiac ECG.

  Junctional bradycardia.

  Lack of response of the atria to direct electrical stimulation.



Atrial standstill may be observed in patients with

  Coronary artery disease

  Acute myocardial infarction

  Congestive heart failure

  Amyloidosis

  Drug intoxication (digitalis, verapamil, quinidine, proscillaridin)

  Isolated noncompaction of right ventricular myocardium

  Hypoxia

  SCN5A mutation

  Ebstein's anomaly

  Idiopathic right atrial dilatation

  Emery-Dreyfuss muscular dystrophy

  Kugelberg-Welander syndrome (spinal muscular atrophy Type III)

  Myocarditis



Atrial standstill

  Atrial standstill may be partial or complete.

  Partial atrial standstill: failure of atrial activity either spontaneously or in response to electrical stimulation in restricted site of atria (diagnosed by electrophysiological study).

  On surface ECG, left atrial standstill may be obscured by the right and left atrial electrical dissociation.

  Atrial standstill may be persistent or reversible. Prolonged, but reversible atrial electrical silence may follow abrupt termination of chronic atrial tachycardias (atrial flutter, ectopic atrial tachycardia)

  It has been suggested that endocrinologic silence (disturbed secretion of atrial natriuretic peptide) accompanies electrical and mechanical silence of the atria during atrial standstill.

  It must be differentiated from fine atrial fibrillation. Unlike atrial fibrillation, there is no oscillating baseline in atrial standstill.



Arrhythmia syndromes associated with mutations in the SCN5A gene (encoding the major
sodium channel in heart) are

  Long-QT syndrome type 3 (LQTS3)

  Brugada syndrome

  Sinus node dysfunction

  Conduction disease

  Atrial standstill



References

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  Jpn Circ J 1996;60:382-388.