cardiovascular disorders
Ectopic Supraventricular Arrhythmias
Nonparoxysmal junctional tachycardia
Nonparoxysmal junctional tachycardia is caused by abnormal automaticity in the AV node or adjacent tissue, which typically follows open heart surgery, acute inferior myocardial infarction, myocarditis, or digitalis toxicity. Heart rate is 60 to 120 beats/minute; thus, symptoms are usually absent. ECG shows regular, normal-appearing QRS complexes without identifiable P waves or with retrograde P waves (inverted in the inferior leads) that occur shortly before (<0.1 second) or after the QRS complex. The rhythm is distinguished from paroxysmal supraventricular tachycardia by the lower heart rate and gradual onset and offset. Treatment is directed at causes. 