These arrhythmia are usually persistent and are called nonparoxysmal.

A. A 20-s continuous recording demonstrates a regular tachycardia at a ventricular rate of approximately 140 per minute. B. During carotid sinus massage, ventricular conduction becomes irregular and diminutive P waves at twice the basic ventricular rate are evident Impaired AV conduction with little or no effect on atrial activity is characteristic of the response of an ectopic atrial tachycardia to carotid sinus massage.

They may be due to reentry or automaticity mechanisms, or could be due to triggered activity.

 

Often a toxic or metabolic cause can be found responsible for the tachycardia.

 

But focal atrial disease may play a part.

 

Digitalis in toxic amounts can cause such an arrhythmia with a rate of 160 to over 200 per minute associated with a 2:1 conduction or variable block (see illustration below).

 

A. Atrial tachycardia with 2:1 AV block due to digitalis intoxication (note diminutive P waves, barely visible even in V1) B. Multifocal atrial tachycardia. Note the constantly changing form of ectopic P waves. Myerburg, R.J., MD, Kessler, K.M., MD, Castellanos, A., MD, Recognition, Clinical Assessment, and Management of Arrhytmias and Conduction Disturbances, Hurst's The Heart, 8th edition, p 705-758.

Decompensated chronic lung disease, acute alcohol abuse, metabolic factors, electrolyte imbalances, and reduced oxygen blood levels (hypoxemia) can cause similar arrhythmias.

 

Also, acute myocardial infarction (heart attack) can be a cause, as well as trauma from prior open heart surgery.

 

The main treatment involves the correction of above causative factors (when identifiable).

 

Since atrial disease is often multicentric, surgical excision is not often used.

 

Antiarrhythmic drugs may help if there is no identifiable cause.