ECG Review: Best Obtainable Tracing

By Ken Grauer, MD

Figure. Best quality tracing obtainable from this 59-year-old
woman with acute dyspnea and chest pain.

Clinical Scenario: The tracing in the Figure was obtained from a 59-year-old woman with a long history of smoking. She presented with acute dyspnea and atypical chest pain. Because of moderate respiratory difficulty, this was the best quality tracing obtainable. In full acknowledgment of its suboptimal technical quality, how would you interpret this ECG? What findings may be of potential concern?

Interpretation/Answer: As stated, the technical shortcomings of this tracing make accurate interpretation problematic. The clinical reality, however, is that optimal quality tracings may not always be obtainable in acutely ill patients, especially when there is respiratory distress.

What can be said about this tracing is that the QRS complex is narrow and that the rhythm is regular at a rate of approximately 150 beats/minute. Upright (sinus) P waves appear to precede each QRS complex in lead II, suggesting that the rhythm probably is sinus tachycardia. There is marked left axis deviation. An rSR' pattern is seen in several of the complexes in lead V1. Precision beyond this point is difficult to attain.

The overall pattern of this ECG is most suggestive of pulmonary disease. If new, these findings could be consistent with acute pulmonary embolism, although they more often reflect the long-standing existence of chronic obstructive pulmonary disease. The finding of a "null vector" (flat complex) in lead I is an interesting manifestation that when seen supports the ECG diagnosis of a pulmonary pattern. Additional findings that further support this impression are the incomplete right bundle branch block (rSR') pattern in lead V1, the relatively tall and somewhat peaked P waves in the inferior leads, and the dropoff in QRS amplitude with minimal R waves and persistent S waves in the lateral precordial leads. Findings of potential concern (especially in view of the history of chest pain on presentation) are apparent small q waves that occur in association with a difficult-to-assess ST segment appearance in each of the inferior leads. The possibility of acute ST segment elevation also exists in leads V3 - V5. Clearly, the patient needs to be monitored, acute serum markers (troponin, CK-MB) should be obtained, and a follow-up ECG should be done as soon as the patient’s clinical condition allows, to confirm sinus tachycardia and rule out the possibility of acute infarction.

Dr. Grauer, Professor and Associate Director, Family Practice Residency Program, Department of Community Health and Family Medicine, College of Medicine, University of Florida, Gainesville, is on the Editorial Board of Emergency Medicine Alert.