Sunday, December 19, 2010

ECG Interpretation Review - #5 (T Wave Inversion, Ischemia, Juvenile T Wave Variant)

QUESTION: Interpret the 12-lead ECG below.
  • Clinically - How would you interpret the anterior T wave inversion (arrows) if this ECG was obtained from a middle-aged adult with chest pain?  Are these changes likely to be acute?
  • How would you interpret this same ECG if instead it was obtained from a healthy 5 year-old?
Figure 1 (ECG reproduced from ECG PB book - pg 2)
Note - Enlarge by clicking on Figures -
INTERPRETATION:  The rhythm is sinus arrhythmia at a rate between 60-70/minute. All intervals (PR, QRS, QT) are normal.  There is RAD (Right Axis Deviation) with a mean QRS axis of about +100 degrees. There is no chamber enlargement.
  •  Q-R-S-T Changes:  - There are small Q waves in the inferolateral leads. R wave progression is normal (with transition occurring between leads V3-to-V4).  Assessment of ST-T wave changes reveals deep symmetric T wave inversion in the anterior precordial leads (arrows in V1,V2,V3).
COMMENT:  - Symmetric T wave inversion will often be seen in the anterior leads (V1,V2,V3) of pediatric patients.  In an otherwise healthy child (with no heart murmur) - this finding represents a benign normal variant (referred to as a "Juvenile" T Wave Pattern).  However, the same ECG (with identical T wave inversion) would have to be interpreted very differently IF the patient in question was an older adult with chest pain (in which case ischemia would be suggested).
  • PEARL:  - Shape of the ST-T wave segment often provides an important clue to clinical significance (Figure 2). Thus, in an older adult with chest discomfort - symmetric T wave inversion (as highlighted by arrows in Figure 1 ) suggests ischemia
  • In contrast - asymmetric ST depression (left panel in Figure 2 ) is much more suggestive of "strain" that accompanies LVH.
Figure 2 - T Wave Morphology - 'Strain" vs Ischemia.
(ECG reproduced from ECG PB book - pg 47)
BOTTOM Line:  Interpretation of the ECG shown in Figure 1 can not be done without provision of at least a brief clinical scenario.
  • Scenario #1 (the patient is a healthy 5-year-old with no heart murmur) - in which case sinus arrhythmia, RAD of this degree, and symmetric T wave inversion in leads V1,V2,V3 are all within the range of normal for the age of the child.
  • Scenario #2 (the patient is a middle-aged adult with chest pain) - in which case one has to be concerned about the possibility of ischemia.  More history and comparison with prior tracings would be needed to determine if these changes are likely to be acute.
NOTE - The Descriptive Analysis for our interpretation is the same in both clinical scenarios (ie, "sinus arrhythmia, RAD, symmetric T wave inversion in V1-to-V3" ) - but our Clinical Impression will be very different depending on whether the patient is a healthy child or an adult with chest pain!
  • P.S. The ECG in Figure 1 might yet be interpreted differently if we had but another setting (ie, ongoing shortness of breath of uncertain etiology). In this instance - one would have to consider pulmonary embolism (despite the relatively slow heart rate) in view of: i) RAD; plus ii) Anterior symmetric T wave inversion, which could be a manifestation of acute right heart "strain" (sometimes seen with acute PE).

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