ECG Review: How Many Early/Blocked Findings?
ECG Review
How Many Early/Blocked Findings?
By Ken Grauer, MD, Professor, Department of Community Health and Family Medicine, University of Florida. Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
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Scenario: The ECG shown above was obtained from a 72-year-old woman as a baseline. How would you interpret her ECG? How many blocked and early findings can you identify?
Interpretation: The underlying mechanism of the rhythm in the 12-lead ECG shown above is sinus, as confirmed by the upright P waves with fixed PR interval for the 2nd and 4th beats in lead II. There is variability in the overall ventricular response, in part due to sinus arrhythmia and in part due to the 3 premature atrial contractions (PACs) that are seen on the tracing. Lack of a lead II rhythm strip makes it more difficult to identify these rhythm characteristics, but the 3rd beat in lead II, the 3rd beat in lead aVL, and the 4th beat in lead V2 (that occurs just before the lead change) are all early beats that are preceded by a premature P wave that notches the preceding T wave. Looking at simultaneously occurring leads aVF (under lead aVL) and V3 (under lead V2) facilitates recognizing the telltale notch in the T waves that precede the PACs in these leads. There is complete right bundle branch block (RBBB), as evidenced by QRS widening, the rsR' in lead V1, and the wide, terminal S waves in leads I and V6. In addition, there is left posterior hemiblock (LPHB), making the conduction disturbance a bifascicular block (RBBB plus LPHB). Because the posterior hemifascicle of the left bundle branch receives a dual blood supply and is much thicker than the anterior hemifascicle, LPHB is far less common than LAHB. The diagnosis is made by the finding of a disproportionately deep S wave in lead I as is seen here, in a patient with underlying RBBB. The occurrence of bifascicular block with LPHB is often associated with more extensive underlying cardiac disease - and the inferior and lateral precordial Q waves seen on this tracing may be indicative of prior infarction in these areas. It is difficult to tell if the ST coving and shallow T wave inversion seen in lead aVL and for the first complex in leads V3,V4 are cause for concern or not.
The ECG shown above was obtained from a 72-year-old woman as a baseline. How would you interpret her ECG? How many blocked and early findings can you identify?Subscribe Now for Access
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