Read more about Complete AV Block With Junctional Escape Rhythm. When R wave progression is not normal, we should also consider electrode misplacement. The QRS complexes in V1 and V2 appear to have pathological Q waves. The R wave progresson on the precordial leads shows a persistently negative QRS with late transition in V5. But, with a normal frontal plane axis, borderline width, and no T wave inversions, the rhythm looks more supraventricular. Some might argue that there is an idioventricular escape mechanism. In this case, the QRS is slightly wide at 112 ms (.11 sec), and the QRS complexes in several leads are fragmented. The junction is the escape focus, producing a narrow-complex rhythm between approximately 40-60 bpm. When there is a third-degree AV block with a narrow-QRS escape rhythm, we can assume the block is in the AV node. We see the classic “AV DISSOCIATION” of complete heart block. There is no irregularity of the QRS rhythm or variation in QRS morphology. Even though some of the P waves LOOK like they have conducted to produce QRS complexes, they have not. The ventricular rhythm, at 40 bpm, is also regular, but is separate from the atrial rhythm. Some of the P waves are “buried” behind QRS or T waves. Here is what we DO see: There is a normal sinus rhythm present, as evidenced by the regular P waves that do not change their morphology. The machine interpretation can serve as a reminder, but should not take the place of human interpretation. ECGs should ALWAYS be interpreted by a knowledgeable person. We break from our usual habit of removing the ECG machine’s interpretation of the ECG to serve as a reminder that the computer interpretation can be wrong. Read more about Junctional or Low Atrial Rhythm. 
Our thanks to Michael Francis and Chris Burden for donating this ECG. He was treated in the hospital and cleared by a cardiologist for discharge two days later. Patient Outcome This patient was diagnosed with orthostatic hypotension, bronchitis, and urinary tract infection. A junctional rhythm may escape when the sinus node fails or there is a complete AV block in the AV node area. The fastest pacemaker controls the heart. When the sinus node speeds up, it may once again take over the heart’s rhythm from the junction. That is, the sinus node begins firing so slowly that the junctional pacemaker “escapes”, and takes control of the heart. There are no T wave inversions, except for aVR, where it is normal.Īssessment One cause of junctional rhythm is sinus brady. There are no premature beats, and the ST segments are not elevated or depressed. This is common in junctional rhythm, as the impulse starts at the AV junction, and travels back through the atria and forward through the ventricles at the same time. The PR interval is on the short side of normal at about. The origin of the P waves has to be the AV junction or the lower atria for this to happen. This is an indication that the P waves are traveling in a “retrograde” fashion – backward. The P waves are negative in Leads II, III, and aVF and positive in aVR. The QRS complexes are narrow, at a little less than. The ECG The 12-lead ECG shows a bradycardia at about 60 beats per minute and regular.
He denied chest pain or shortness of breath. The Patient This ECG was recorded from an 86-year-old man who was weak, pale, and diaphoretic.
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