Determine the following:
Rhythm: _______________________________________
Rate: ___________________________________________
P waves: _______________________________________
PR interval: ____________________________________
QRS complex: __________________________________
What's your interpretation?
(Answers on next page)
Name that strip: Answers
Rhythm: Regular
Rate: 107 beats/minute
P waves: Inverted before QRS complex
PR interval: 0.08 second
QRS complex: 0.08 to 0.10 second
Interpretation: Paroxysmal junctional tachycardia
Paroxysmal junctional tachycardia (PJT) is a dysrhythmia originating in the AV junction with a heart rate exceeding 100 beats/minute. PJT commonly starts and stops abruptly (like paroxysmal atrial tachycardia) and is often precipitated by a premature junctional complex (PJC). Three or more PJCs in a row at a rate exceeding 100 per minute constitute a run of junctional tachycardia.
PJT is regular with a heart rate exceeding 100 beats/minute. The P waves are inverted in lead II (a positive lead) and occur immediately before or after or hide within the QRS complex. The PR interval, when present, is short (0.10 second or less). The QRS duration is usually normal. PJT has the same ECG features as junctional rhythm and accelerated junctional rhythm. This rhythm is differentiated from the other junctional rhythms by the heart rate, and its abrupt beginning and end. PJT is not a common rhythm.
PJT may result from enhanced automaticity of the AV junction caused by digitalis toxicity, which is the most common cause. The rhythm may also be caused by damage to the AV junction from myocardial infarction (MI), especially inferior wall MI.
PJT may lead to a decrease in cardiac output related to the faster heart rate as well as the loss of the atrial kick secondary to retrograde depolarization of the atria. Treatment is directed at reversing the consequences of reduced cardiac output as well as identifying and correcting the underlying cause of the dysrhythmia. All medications should be reviewed and discontinued if indicated as prescribed.
Paroxysmal junctional tachycardia: Identifying ECG features
Rhythm: Regular
Rate: >100 beats/minute
P waves: Inverted in lead II and occurs immediately before or after or hides within the QRS complex
PR interval: Short, if present, (0.10 second or less)
QRS complex: Usually normal (0.10 second or less)