med 18

 

of gastrointestinal bleeding, and document a thorough

neurologic exam in patients who may require treatment

with anticoagulant or thrombolytic medications.

DIAGNOSTIC STUDIES

� Electrocardiogram

Obtain a 1 2-lead ECG immediately on presentation for

patients with symptoms concerning for ACS. The emergent identification of a STEM! ensures that definitive

therapy can be arranged as quickly as possible to limit

further myocardial loss. The use of prehospital ECG analysis has further reduced any delays in appropriate therapy.

Keep in mind that a single ECG provides only an isolated

snapshot of myocardial electrical activity, and as s uch, any

changes in clinical status should prompt repeat testing. In

addition, fewer than half of all AMis are of the STEM!

variety, and ECG interpretation may be completely normal

in the setting of NSTEMI or UA. ST-segment elevations

suggest the presence of an acute transmural infarction,

whereas ST-segment depressions suggest active myocardial

ischemia. The morphology of the ST-segment elevations

CHAPTER 14

Table 1 4-1. Anatomical reg ions of the hea rt

by ECG ana lysis.

Anatomic occluded Ischemic Reciprocal

Location Artery Leads Leads

Anterior wall LAD V2, V3, V4 II, Ill, aVF

Lateral wall LCX I, aVL, VS, V6 V1, V2

Inferior wall RCA, LCX II, Ill, aVF variable

Posterior RCA, LCX VB, V9 V1, V2

Right ventricle RCA V1, V4R Variable

with AMI is typically straight or convex upward ("tomb ­