[Paroxysmal sinoatrial tachycardia. Apropos of 44 cases].

44 cases of paroxysmal sinoatrial tachycardia (PAT) due to reentry within the sinus node or between the sinus node and the atrium are reported; these tachycardias are usually quite well tolerated clinically as the rhythm is rarely faster than 140/min and they are often degraded by functional AV block. They can be triggered and terminated by one (or two) atrial stimuli, and reduced by carotid sinus massage but relapse in the short term. They often alternate with a disturbance of atrial excitability in patients who also have binodal disease. Their diagnosis implies endocavitary investigation showing sinusal anterograde atrial activation and atrial and ventricular stimulation to differentiate them from other types of paroxysmal tachycardia, especially those due to reentry involving concealed right sided Kent bundles. Studies of sinus node function by atrial extrastimulus techniques in 38 patients usually showed an isolated and prolonged Zone I followed, without a transitional plateau, by a Zone IV of sinus echos during which the tachycardia could be triggered. This type of tachycardia, without doubt as common as junctional tachycardia, may respond to treatment with Quinidine, Amiodarone, Verapamil, or beta-blockers, associated with permanent pacing in cases of binodal block.