American Journal of Critical Care. 2004;13: 437-438
A regular feature of the American Journal of Critical Care, the ECG Puzzler addresses ECG interpretation for clinical practice. We welcome letters to the Editors regarding this feature.
An Evolving Myocardial Infarction
By
Mary G. Adams, RN, PhD and
Michele M. Pelter, RN, PhD.
From the School of Nursing at State University of New York at Buffalo (MGA) and Washoe Health System, Reno, NV (MMP).
Scenario: This is a routine postoperative 12-lead ECG waveform. The patient is an 85-year-old white woman who has been admitted to the cardiothoracic intensive care unit (ICU) after undergoing abdominal aortic aneurysm repair. In following with the cardiothoracic ICU’s critical care pathway, the patient should be aroused and extubated within the next 4 hours.
Interpretation: Normal sinus rhythm at 70 beats per minute with an acute inferior lateral myocardial infarction (MI) with evolving T-wave changes.
Rationale
Octogenarian status (age >80 years old) no longer precludes f it patients from aggressive surgeries, including abdominal aortic aneurysm repair. However, the rate of perioperative infarction is significant in this population. Given that cardiac monitoring is the standard of care in the ICU, postoperative complications related to the cardiovascular system can be detected quickly. In this 12-lead ECG waveform, although the ST deviation is not 2 mm, there is at least 1 mm of ST elevation in leads II, III, aVF, V5, and V6, indications of both inferior and lateral wall involvement. All the leads with ST elevation also have q waves greater than 30 ms and T-wave inversion, indicating that this patient is possibly in the evolutionary phase of infarction. Therefore, it is likely that this patient infarcted during the perioperative phase.
Nursing Actions
The acute ST elevation requires immediate attention and consideration of reperfusion therapy. Continued sedation may actually protect the patient’s myocardium, whereas arousing the patient for extubation would only increase her myocardial oxygenation demands, possibly extending the MI. Given the patient had elective surgery, a prior 12-lead ECG waveform should be available for comparison to determine if the q waves of infarction were present before the operation. This patient’s critical care pathway is likely to be delayed given her perioperative complication of an acute MI.
