Diagnosis: Normal sinus rhythm, interpolated junctional premature complexes in a bigeminal pattern.
Circulation ECG Challenge Response! Regarding the 57 year old man with a cough and fever:
Diagnosis: Normal sinus rhythm, interpolated junctional premature complexes in a bigeminal pattern.
There is an irregular rhythm, although there is group beating, with long intervals that are all the same (↔) and short RR intervals that are the same. The average rate is 120 bpm. The short intervals are the result of premature complexes. There are 4 much longer RR interval (↔) and there a distinct P waves at the end of each of these longer intervals (+). The P waves are positive in leads I, II, aVF and V4-V6. Hence these are sinus P waves and they are associated with a stable PR interval (0.16 sec). Complexes 5-6 are two sequential sinus complexes; the rate is 76 bpm. Based on this PP interval it can be seen that there are P waves (*) seen before every other QRS complex and the PP interval is stable (└┘) at a rate of 76 bpm. Therefore there is an underlying sinus rhythm. The QRS morphology of the sinus complexes is normal and there is a normal duration (0.08 sec). The axis is leftward at approximately -30° (positive QRS complex in lead I, negative QRS complex in lead aVF and biphasic in lead II. There are nonspecific ST-T wave abnormalities (^) in leads I, aVL, and V6 (^). The QT/QTc intervals are normal (320/450 msec). The premature QRS complex has the same morphology as the sinus complex but there is no preceding P wave. Therefore these are premature junctional complexes. As every other QRS complex is a premature junctional complex, this is junctional bigeminy. Additionally there is no pause following the premature complex and the PP interval surround the premature complex is the same as the sinus interval. Hence these are interpolated premature junctional complexes in a bigeminal pattern. Also supporting the junctional etiology is that the junctional complexes have a different amplitude compared to the sinus complexes. This is due to the fact that the impulse generated from a junctional focus enters the bundle of His at a different location compared to impulses coming though the AV node. Conduction through the Purkinje system therefore is different.
