Correspondence

Right Ventricular Infarction

N Engl J Med 1994; 331:681September 8, 1994

Article

To the Editor:

Kinch and Ryan (April 28 issue) present an excellent review of the pathogenesis, pathophysiology, diagnosis, complications, and treatment of the right ventricular infarction that commonly accompanies inferior myocardial infarction1. I would like to point out that it is not necessary to use lead V_4R or any additional precordial leads to make an electrocardiographic diagnosis of right ventricular infarction if the Grant method of electrocardiographic interpretation is used. The routine 12-lead electrocardiogram is sufficient2-5.

The mean ST-segment vector is directed toward the epicardial injury that surrounds the dead zone of infarction. When the mean ST-segment vector is directed inferiorly, to the right, and anteriorly, one should be concerned about the possible presence of right ventricular infarction. The farther the mean ST-segment vector is directed to the right and anteriorly, the more likely it is that the body of the right ventricle is infarcted.

One should realize that the electrocardiographic abnormalities produced by myocardial infarction may be recorded in lead V_4R or some other right precordial leads when the right ventricle is not infarcted. This can occur when the mean ST-segment vector is directed to the left and markedly anteriorly, as it often is with an anterior infarct. This error can be made if one ignores the frontal-plane direction of the electrical forces produced by the infarction.

I believe, as Grant did, that it is important to identify the direction and magnitude of the electrical forces that are responsible for electrocardiographic abnormalities2. When this is done and when one considers the anatomical location of the left ventricle (including the septum) and the right ventricle, one is able to deduce with reasonable accuracy the location of epicardial injury associated with infarction.

It is time to reemphasize Grant's concepts2-4.

J. Willis Hurst, M.D.
Emory University School of Medicine, Atlanta, GA 30322

5 References

1. 1

   Kinch JW, Ryan TJ. Right ventricular infarction. N Engl J Med 1994;330:1211-1217
   Full Text | Web of Science | Medline

2. 2

   Grant RP. Clinical electrocardiography: the spatial vector approach. New York: McGraw-Hill, 1957.
   

3. 3

   Hurst JW. Ventricular electrocardiography. New York: Gower Medical Publishing, 1991.
   

4. 4

   Hurst JW. Cardiovascular diagnosis: the initial examination. St. Louis: Mosby-Year Book, 1993.
   

5. 5

   Hurst JW. Detection of right ventricular myocardial infarction associated with inferior myocardial infarction from the standard 12-lead electrocardiogram. Heart Dis Stroke 1993;2:464-467
   Medline

Author/Editor Response

The authors reply:

To the Editor: We agree with Dr. Hurst that it is important to reemphasize Grant's concepts of spatial-vector electrocardiography and that there is a role for these concepts when interpreting the routine electrocardiogram to diagnose right ventricular infarction.

Dr. Hurst states that when the mean ST-segment vector is directed inferiorly, to the right, and anteriorly, one should be concerned that right ventricular infarction may be present. More important, he also suggests that the extent of right ventricular infarction may be estimated, with an ST-segment vector from 90 degrees to 120 degrees indicating a small right ventricular infarct, whereas an ST-segment vector of 150 degrees to 180 degrees indicates a large right ventricular infarct1. This is consistent with the principles of spatial-vector electrocardiography; however, to our knowledge the diagnostic accuracy of this method for assessing right ventricular infarction has not been determined.

Andersen and colleagues2 did examine the diagnostic value of an ST-segment elevation ≥ 1 mm in lead II, with an ST-segment elevation in lead III exceeding that in lead II, to determine right ventricular infarction. This is indicative of an ST-segment vector of 90 degrees directed inferiorly and to the right. Using postmortem determination of infarction as the diagnostic gold standard, Andersen et al. determined that this method is 63 percent sensitive and 88 percent specific in diagnosing right ventricular infarction, which is slightly more sensitive but less specific than the right-sided chest leads. The investigators concluded that this method can be used to diagnose right ventricular infarction but that the diagnosis may be made more readily with right-sided chest leads2.

There is some advantage to the simplicity of determining the absence or presence of a 1-mm elevation in the ST segment in lead V_4R, a pattern that can easily be interpreted by cardiologists, internists, and emergency department staff. However, we do agree with Dr. Hurst that recognizing the direction and magnitude of an electrocardiographic vector provides more insight into the physiologic process than simply recognizing a pattern on the electrocardiogram. Unquestionably, there is much to be gained from Grant's approach to understanding the electrocardiogram, and we thank Dr. Hurst for pointing us in that direction3.

Jack W. Kinch, M.D.
Thomas J. Ryan, M.D.
Boston University Medical Center, Boston, MA 02118

3 References

1. 1

   Hurst JW. Detection of right ventricular myocardial infarction associated with inferior myocardial infarction from the standard 12-lead electrocardiogram. Heart Dis Stroke 1993;2:464-467
   Medline

2. 2

   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
   CrossRef | Web of Science | Medline

3. 3

   Grant RP. Clinical electrocardiography: the spatial vector approach. New York: McGraw-Hill, 1957.