[Atrioventricular nodal reentrant tachycardia--arrhythmias mechanism, clinical feature and electrocardiographic recordings].

Atrioventricular nodal reentrant tachycardia (AVNRT) is probably the most common form of paroxysmal supraventricular tachycardia. It has two usual types of surface ECG patterns. In the so-called "common, usual, or typical" form of AVNRT the retrograde P wave is seen in close proximity to the QRS complex. In the "uncommon, unusual, or atypical" form of AVNRT the retrograde P wave occurs late, within or following the T wave. In the common type of AVNRT the reentrant circuit consists of the slow pathway in the anterograde direction and the fast pathway retrogradely. In the uncommon type of AVNRT the slow pathway is utilized retrograde and a relatively fast pathway is utilized in the anterograde direction. Common symptoms include palpitations, nervousness, anxiety, lightheadedness, neck and chest discomfort, and dyspnea. AVNRT may cause or worsen heart failure in patients with poor left ventricular function. It may cause angina or myocardial infarction in patients with coronary artery disease. Syncope may occur in patients with a rapid ventricular rate or prolonged tachycardia due to poor ventricular filling, decreased cardiac output, hypotension, and reduced cerebral circulation.