ECG Review: A Rhythm "in Hiding"
ECG Review
A Rhythm "in Hiding"
By Ken Grauer, MD, Professor, Assistant Director, Family Practice Residency Program, University of Florida. Dr. Grauer reports no financial relationship to this field of study.
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Figure. 12-lead ECG obtained from a 77-year-old woman with "heart problems." |
Clinical Scenario: The ECG in the Figure was obtained from a 77-year-old. woman with a history of "heart problems." What can (and can not) be said about this tracing?
Interpretation/Answer: Although there is no lead II rhythm strip, it is obvious that the rhythm is irregular. Atrial activity is not seen in lead II. However, regular atrial activity is seen in lead V1 in the form of pointed waveforms spaced at an interval of approximately one large box. Although these pointed waveforms are not seen throughout lead V1 (ie, a "rhythm in hiding")—careful inspection reveals perfectly timed spiking at the beginning or end of QRS complexes plus clear peaking of the T wave of the 3rd QRS complex in lead V1. Regular pointed atrial activity in lead V1 is characteristic of a form of atrial flutter, seen here in association with a slow and variable ventricular response. A PVC (premature ventricular contraction) is seen (the 2nd beat in simultaneously recorded leads aVR, aVL, aVF). QRS complexes in this tracing are wide, with a morphology that defines the conduction defect as complete LBBB (left bundle branch block). Although chamber enlargement is difficult to diagnose in the setting of QRS widening, the very deep S wave in lead V1 (exceeding 25 mm) suggests that LVH (left ventricular hypertrophy) is probably present. There are obvious ST-T wave abnormalities in all lateral leads, however the significance is uncertain in the setting of LBBB.
Elderly patients with LBBB almost always have significant cardiac disease (ie, hypertension, cardiomyopathy, coronary artery and/or valvular heart disease). Of potential concern is the relatively slow ventricular response to this patient’s atrial flutter. The frequency of ventricular ectopy cannot be determined from this single tracing. Clinical correlation is essential to find out if the patient is symptomatic, and if factors such as ischemia, heart failure, electrolyte abnormality, hypoxia, digoxin or other drug toxicity are operative.
The ECG in the Figure was obtained from a 77-year-old. woman with a history of "heart problems." What can (and can not) be said about this tracing?Subscribe Now for Access
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