Page 345 - Cardiac Nursing

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■ Figure 15-32 (A) Acute RVMI. ST elevation is present in leads II, III, aVF, and V 1 ; recip- V5 R R R R R R R R
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rocal ST depression in all other leads. Note the discordant ST elevation in V 1 and depression in
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V 2 . (B) Acute inferior MI with probable right ventricular involvement. Large ST elevations in
leads II, III, and aVF with reciprocal depression in I and aVL indicates the inferior MI. Note
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minor ST elevation in V 1 with minor ST depression in V 2 , raising suspicion about right ven-
tricular involvement. (C) Right-sided leads from the patient in (B) showing ST elevation in V6 R R R R R R R R
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ECG Diagnosis of UA/NSTEMI is NSTEMI. The two conditions share the same pathophysiol-
ogy and differ only in degree of severity, and they appear identi-
UA and NSTEMI are subsets of ACS and are diagnosed when cal on the ECG.
the ECG shows ST depression or prominent T-wave inversion The terms Q-wave MI and non–Q-wave MI are used to describe
without the presence of ST elevation in patients with chest pain the presence or absence of Q waves on the ECG when the diagno-
typical of ACS. 10,19 The differential diagnosis is made based on sis of MI has been established. Non–Q-wave MI has traditionally
the presence or absence of cardiac biomarkers, specifically tro- been considered to involve necrosis of the subendocardial layer of
ponin and/or creatine kinase MB isoenzyme (CK-MB). If is- the ventricle and not the entire thickness of the ventricular wall.
chemia is present without resulting myocardial injury, biomark- Necrosis of sufficient myocardium can lead to loss of R-wave am-
ers are negative and the diagnosis is UA. If ischemia is severe plitude rather than to development of Q waves in leads facing the
enough to result in injury with biomarker release, the diagnosis infarcted area (see Fig. 15-24). Most patients who present with