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Arrhythmia Recognition Webcast Series
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Practice ECG 23
This is another tough ECG to interpret, but have faith. Be systematic in your approach.
This one shows evidence of LAE with a large, wide terminal portion of the biphasic P wave in V1. In addition, there is evidence of RAE with the initial portion taller in V1 than in V6. There is also evidence of LVH: the sum of the S wave in V2 and the R wave in V3 is more than 35 mm.
In what quadrant is the axis located? It will be found in the right quadrant, so this patient has a right axis deviation. Whenever we have an axis in the right quadrant we need to consider an LPH. Does this patient have an LPH? Well, the axis is in the right quadrant. Are any of the exclusionary criteria met? Yes, the patient has RAE, so this could not be an LPH. Then why does this patient with significant LVH have a right axis deviation? Take a close look at leads I and III. You will see an S wave in lead I, a Q wave in III, and a flipped T in III-an S1Q3T3 pattern. This is found in patients with right ventricular strain from various sources-pulmonary embolus, right ventricular hypertrophy, and so on. In general, the S1Q3T3 pattern produced by an acute process will not show RAE because the atrium has not had time to enlarge or hypertrophy. The presence of RAE, therefore, leads one to believe that this patient probably has a chronic right ventricular strain pattern, commonly caused by right ventricular hypertrophy. Putting it all together, we have a patient with four-chamber enlargement, most probably a cardiomyopathy. Not bad for a noninvasive bedside test that takes only a few minutes to obtain with no risk to the patient . All of this for a very nominal cost!
By the way, this is sinus tachycardia, and there is a VPC present. The QT interval is prolonged for a patient that is tachycardic.
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