ECG Challenge: A 56-year-old man with a history of prostatic hypertrophy presents to the emergency department with a concern about the inability to void. He is observed to have urinary retention and a Foley catheter is inserted. He is admitted to the hospital and placed on telemetry. An ECG is obtained (ECG A). Several hours after admission he spikes a temperature to 102°F and is felt to have a urinary tract infection and antibiotics are begun. The nurse notes a change in his QRS complexes on telemetry and an ECG is repeated (ECG B).
ECG A shows a regular rhythm with a rate of 64 bpm. There is a P wave before each QRS complex (+) with a stable PR interval (0.18 second). The P waves are positive in leads I, II, aVF, and V4 through V6. Hence, this is a normal sinus rhythm. The QRS complexes are narrow (0.08 second) and have a physiological left axis between 0° and –30° (positive QRS complex in leads I and II and negative in aVF). The morphology is normal except for a positive waveform noted at the end of the QRS complex in lead V1 (↓). This is suggestive of either early repolarization or possibly an R′, consistent with an intraventricular conduction delay to the right ventricle. In addition, there is J-point elevation in lead V2 (^) that is suggestive of early repolarization. There is early transition with a tall R wave in lead V2 (←); this is termed counterclockwise rotation of the electric axis in the horizontal plane. This is established by imagining the heart as if viewed under the diaphragm. With early transition, the left ventricular forces develop early and appear in the right precordial leads. The QT/QTc intervals are normal (400/415 ms).
ECG B was obtained several hours later when the patient was febrile. There is a regular rhythm at a rate of 100 bpm. There is a P wave before each QRS complex (+) with a stable PR interval (0.16 second). The P waves are positive in leads I, II, aVF, and V4 through V5. Thus, this is a sinus tachycardia. The QRS complex duration and axis are the same as seen in ECG A. The QT/QTc intervals are the same (320/415 ms). Although the QRS complex morphology is similar to the QRS complexes in ECG A, there are changes in leads V1 through V2. Lead V1 shows marked J-point and ST-segment elevation (v). This has been termed a pseudo right bundle-branch block, and it may also be confused with ST-segment elevation because of an acute myocardial infarction. However, the J point is elevated and there is a slowly downsloping ST segment that merges with an inverted T wave. In V2, there is J-point and ST-segment elevation (↓). The ST segment is notched. This has been called saddle back ST elevation. The abnormalities seen in leads V1 through V2 are typical for a Brugada pattern (type 2). Although ECG A has an abnormality noted in lead V1 through V2, this is not a typical Brugada pattern, although it is suggestive. However, with an elevated temperature, a typical Brugada pattern is exposed.
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- © 2014 American Heart Association, Inc.