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By Ken Grauer, MD
Figure. 12-lead ECG obtained from a healthy, asymptomatic 42-year-old man. How many findings can you identify?
Clinical Scenario: The ECG in the Figure was obtained from a healthy, asymptomatic 42 year old man. This ECG was done as part of his routine insurance physical examination. How many ECG findings can you identify on this tracing? Given the above scenario, are any of these findings likely to be of clinical significance?
Interpretation/Answer: The underlying rhythm in this tracing is sinus. Two PACs (premature atrial contractions) are seen: beats X and Y. The first PAC (beat X) manifests a different P wave morphology (it is of small amplitude and biphasic). It conducts normally. The second PAC follows the QRS complex labeled Y, and is identified as a subtle notching of the T wave in lead V1 and slight peaking of the T wave in leads V2 and V3. Support that these admittedly subtle alterations in T wave morphology truly reflect a hidden PAC is forthcoming from the relative pause in the rhythm following beat Y. Thus, this second PAC that occurs much earlier in the cycle than the first PAC is "blocked" (ie, not conducted to the ventricles).
The other ECG findings on this tracing include RAD (right axis deviation), small septal q waves in the inferolateral leads, an rSr’ pattern in lead V1, and slight J point ST segment elevation with subtle J point notching in the lateral precordial leads as well as lead II.
Clinical correlation is the key to interpreting the likely significance of the ECG findings seen here. One should inquire if the patient is aware of the "skipped beats" (ie, PACs) seen here, and if potential causes may exist (ie, caffeine consumption or stimulant medications). RAD and the rSr’ in lead V1 are commonly seen normal variants in otherwise healthy young adults, but one should be sure there is no right-sided heart murmur or other evidence of pulmonary or valvular disease. J point ST segment elevation and notching almost certainly reflects a normal variant early repolarization pattern in this asymptomatic patient without any history or symptoms of pericarditis or ischemia.
Dr. Grauer, Professor, Assistant Director, Family Practice Residency Program, University of Florida, is Associate Editor of Internal Medicine Alert.