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ELECTROCARDIOGRAPHIC REPORT
Use of indicative and reciprocal electrocardiographic
changes to help localize the site of coronary occlusion
D. LUKE GLANCY, MD, AND WALEED DOGHMI, MD
Figure 1. The electrocardiogram recorded when the patient arrived in the emergency department.
A
61-year-old man came to the emergency department
complaining of chest pain, and an electrocardiogram
was recorded (Figure 1). Acute inferior myocardial infarction is indicated by ST-segment elevation and broad upright
T waves in leads II, III, and aVF. These changes are mirrored
perfectly by reciprocal ST depression and T-wave inversion in
leads I and aVL. Both indicative and reciprocal changes are striking in this electrocardiogram, but at times, reciprocal or mirrorimage changes are more easily recognized than indicative
changes and are the clue to the correct diagnosis (1). Reciprocity works both ways, and reciprocal ST depression may be seen
in the inferior leads in high lateral myocardial infarction when
ST elevation occurs in leads I and aVL.
The standard 12-lead electrocardiogram does not record from
the back of the chest or the right side of the chest, and as a consequence, important information may go undetected (2, 3). The
anterior chest leads (V1 through V3), however, are the reciprocals of leads on the back of the chest. Thus, early in posterior
myocardial infarction when ST elevation and broad upright T
waves would be recorded on the back of the chest, ST depression and T-wave inversion can be recorded in the anterior precordial leads (4). Such a reciprocal change is seen in lead V2 of
this electrocardiogram.
Why is there no ST depression or T inversion in lead V1? In
fact, there is ST elevation with an upright T in V1 because right
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ventricular infarction coexists. Its anteriorly directed current of
injury obscures the changes of posterior infarction. This patient’s
right ventricle lies more squarely beneath lead V1 than V2, and
the reverse is true for the posterior wall of the left ventricle. In
the presence of changes of acute inferior myocardial infarction,
ST elevation in V1 with depression in V2 is a quite specific (virtually pathognomonic), but rather insensitive, marker of right
ventricular as well as posterior infarction (5).
Other electrocardiographic signs of right ventricular infarction in patients with acute inferior infarction are ST elevation
in lead III exceeding that in lead II (6) and a ratio of ST depression in V2 to ST elevation in aVF of ≤50% (7). The best electrocardiographic guide to right ventricular infarction is an
electrocardiogram with right precordial leads (Figure 2). The
electrocardiogram recorded at 12:34, after initiation of thrombolytic therapy, shows ST elevation in right precordial leads V3R
through V6R, indicating right ventricular infarction, and further
evolution of the changes of inferior myocardial infarction in leads
II, III, and aVF. Persistent ST depression is seen in V1R (left-sided
From the Section of Cardiology, Department of Medicine, Louisiana State University Health Sciences Center and University Hospital, New Orleans, Louisiana.
Corresponding author: D. Luke Glancy, MD, Section of Cardiology, Department
of Medicine, Louisiana State University Health Sciences Center, 1542 Tulane Avenue, Room 441, New Orleans, Louisiana 70112.
BUMC PROCEEDINGS 2001;14:104–105
Figure 2. The electrocardiogram recorded 2 hours later during thrombolytic therapy. The precordial leads were recorded on the right side of
the chest.
V2), and T waves are upright. These reciprocal changes of ST
elevation and T inversion on the back of the chest indicate further evolution of posterior infarction.
Small portions of the right ventricle may receive blood supply from the left anterior descending and/or left circumflex coronary arteries, but most right ventricular blood supply is from the
right coronary artery. Consequently, all clinically significant right
ventricular infarcts are due to occlusion of the right coronary
artery, usually in its proximal portion. Such is the case in this
patient, whose right coronary arteriogram, performed a week
later, reveals severe narrowing proximal to any right ventricular
branch except the conus branch (Figure 3). The right coronary
artery also gives rise to the posterior descending artery and left
ventricular branches, accounting for the inferior and posterior
distributions, respectively, of this patient’s infarction.
Figure 3. Right coronary cinearteriograms recorded a week later in the
cranial (a) left anterior and (b) right anterior oblique projections. In each,
the culprit lesion is seen as an irregular, hazy narrowing (arrow) just
proximal to the first of 3 right ventricular branches. l indicates left ventricular branches; p, posterior descending artery.
JANUARY 2001
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depression in aVL: a sensitive marker for acute inferior myocardial infarction. Eur Heart J 1993;14:4–7.
2. Casas RE, Marriott HJ, Glancy DL. Value of leads V7–V9 in diagnosing posterior wall acute myocardial infarction and other causes of tall R waves in
V1–V2. Am J Cardiol 1997;80:508–509.
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diagnostic value of an ECG containing leads V4R, V8, and V9: the 15-lead
ECG. Ann Emerg Med 1993;22:786–793.
4. Boden WE, Kleiger RE, Gibson RS, Schwartz DJ, Schechtman KB, Capone
RJ, Roberts R. Electrocardiographic evolution of posterior acute myocardial
infarction: importance of early precordial ST-segment depression. Am J
Cardiol 1987;59:782–787.
5. Marriott HJL. Pearls and Pitfalls in Electrocardiography. Philadelphia: Lea and
Febiger, 1990.
6. Andersen HR, Nielsen D, Falk E. Right ventricular infarction: diagnostic
value of ST elevation in lead III exceeding that of lead II during inferior/
posterior infarction and comparison with right-chest leads V3R to V7R. Am
Heart J 1989;117:82–86.
7. Lew AS, Laramee P, Shah PK, Maddahi J, Peter T, Ganz W. Ratio of STsegment depression in lead V2 to ST-segment elevation in lead aVF in evolving inferior acute myocardial infarction: an aid to the early recognition of
right ventricular ischemia. Am J Cardiol 1986;57:1047–1051.
USE OF INDICATIVE AND RECIPROCAL ELECTROCARDIOGRAPHIC CHANGES
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