Summary of common controversies in ECG interpretation
Question 1: Q waves are only present in leads V1 and V2. Should myocardial infarction be diagnosed? Recommendation: No. It is important to follow strict interpretation criteria when reading the ECG. To establish an anterior interval myocardial infarction, Q waves must be present in leads V1, V2 and v3. In daily clinical practice, the presence of Q waves in leads v1 and v2 alone is often diagnosed as “probable” anterior wall myocardial infarction or low antegrade potential. Although this statement is accepted in clinical cardiology, Q-wave myocardial infarction should not be diagnosed in standardized tests.
Question 2: Should other ECG diagnoses be made when the ECG suggests acute myocardial infarction? Recommendation: Yes. When acute myocardial infarction is associated with typical ST-segment elevation, the diagnosis should also be made Article 65 (ST-segment and/or t-wave abnormalities suggesting myocardial injury). This diagnosis is also definitely required in posterior wall myocardial infarction with ST-segment depression in leads V1 and V2.
Question 3: Should acute myocardial infarction also be diagnosed in the presence of left bundle branch block? Recommendation: No (controversial). Most ECG reporters are reluctant to diagnose acute myocardial infarction when they have already diagnosed left bundle branch block. However, “the following three indicators can be used as an independent basis for the diagnosis of acute myocardial infarction (Article 65): ST-segment elevation ≥ O.1 mV and consistent with the direction of the main QRS wave; ST-segment depression ≥ O.1 mV in leads V1, v2, or v4; ST-segment elevation ≥ 0.5 mV and inconsistent with the direction of the main QRS wave.
Question 4: In acute myocardial infarction, one part of the ECG shows ST-segment elevation while the other part shows ST-segment depression, is it necessary to diagnose both ST-T changes suggesting myocardial injury and myocardial ischemia? Recommendation: Many acute myocardial infarctions present with ST-segment elevation in some leads and ST-segment depression in other leads; ST-segment depression is usually a sign of ischemia immediately adjacent to or away from the infarcted area. Thus, the correct diagnosis should include article 64 (ST-segment and/or T-wave abnormalities suggesting myocardial ischemia) and article 65 (ST-segment and/or T-wave abnormalities suggesting myocardial injury). To add: the effect of the infarct focus on the dorsal lateral leads should of course be taken into account.
Add: 1. With Q-wave infarct contralateral leads, not only will there be st depression, but theoretically there will also be R elevation, T upright and elevation. ECG is very complex, specific analysis of specific problems, sensitivity specificity than contrast has a certain lack, this article focuses on the positive consideration of ischemic injury around the infarct foci OR beyond. Of course, in the specific analysis, the effect of infarct foci on so leads will certainly be taken into account and discerned in order to make intervention actions as soon as possible. Thank you for adding. The so-called diagnosis is only a ready-made criterion and a clinical necessity, and the controversy is inevitable in terms of its inability to serve as a gold standard.
Question 5: Should a patient with chest pain presenting with ischemic ST-segment elevation without pathological Q waves be diagnosed with acute myocardial infarction? Recommendation: No. The presence of convex upward ST-segment elevation without abnormal Q waves in chest pain should be diagnosed according to Article 65 (ST-segment and/or T-wave abnormalities suggesting myocardial injury). Clinically, this is usually indicative of an early stage of acute infarction (or transient coronary spasm and/or obstruction), and most patients require urgent pharmacologic or mechanical intervention to restore coronary flow to rescue the endangered myocardium. However, the absence of pathologic Q waves (or the absence of pathologic R waves in posterior wall myocardial infarction) should not diagnose acute myocardial infarction.
Question 6: With so many criteria for diagnosing left ventricular hypertrophy, which is the gold standard? Recommendation: Cornell’s criteria (Ravl ten Sv3 > 2.8mV in men > 2.OmV in women) are probably the most accurate voltage criteria. However, many ECGs meet the diagnostic criteria for LV hypertrophy in some parts and not in others, and all diagnostic indicators of LV hypertrophy are only relatively sensitive when considered in isolation. Thus, it is desirable to know most or all of the various indicators for the diagnosis of LV hypertrophy (Article 40). If there is left ventricular hypertrophy with a “strain” pattern, do not forget to diagnose it according to article 67 (ST-segment and/or T-wave abnormalities secondary to hypertrophy).
Question 7: What are the most important diagnostic criteria for right ventricular hypertrophy? Recommendation: Right ventricular hypertrophy is as difficult to diagnose as left ventricular hypertrophy because a large number of different diagnostic criteria have been proposed for its diagnosis, and there is no single index that can diagnose right ventricular hypertrophy. Important diagnostic criteria include rightward deviation of the electrical axis and R-wave dominance in leads V1 and V2 with secondary St-segment and or t-wave changes. It is also common to have atrial abnormalities. If repolarization abnormalities are present, remember to diagnose #67 (ST-segment and/or T-wave abnormalities secondary to hypertrophy).
Question 8: In second- or third-degree AV block, if the PR interval is greater than 0.20 seconds, is there also a diagnosis of first-degree AV block? Recommendation: No. It is not necessary to diagnose first degree AV block when a higher degree of AV block is present.
Question 9: In junctional or ventricular rhythm, is it necessary to diagnose the underlying atrial rhythm if it is present? If an atrial rhythm is also present in the presence of a predominant junctional or ventricular rhythm, an atrial rhythm (and AV block, if present) should also be diagnosed (e.g., ventricular escape rhythm and sinus rhythm with third-degree AV block).
Question 1O: Should electrical axis left deviation be diagnosed in the presence of left anterior branch block? Similarly, in the presence of a left posterior branch block, should a rightward deviation of the electrical axis be diagnosed? Recommendation: No. It is redundant to describe the electrical axis in the presence of left anterior branch block or left posterior branch block.
Question 11: When should myocardial infarction be diagnosed in the presence of WPW-type preexcitation? Recommendation: Acute myocardial infarction should not be diagnosed in the presence of WPW-type preexcitation because most Q waves are actually negative delta waves, thus creating a pseudo-infarct pattern.
Question 12: Should the intermittent insertion of atrial flutter graphics (i.e., flutter/flutter waves) in atrial fibrillation be diagnosed as atrial fibrillation or atrial flutter? Suggestion: This is a diagnosis of atrial fibrillation, and atrial flutter should be a continuous flutter wave without scattered insertion of flutter waves.
Question 13: Left ventricular hypertrophy with “strain” pattern (ST-segment depression and T-wave inversion) is evident in the lateral wall leads. Should the diagnosis be Article 64 “ST-segment and/or T-wave abnormalities suggesting myocardial ischemia”. Recommendation: No. When left ventricular hypertrophy with strain is present, the diagnosis should be Article 40 (left ventricular hypertrophy) and Article 67 (ST-segment and/or T-wave abnormalities secondary to hypertrophy).
Question 14: Narrow QRS wave tachycardia without P waves is seen in the whole frame ECG, should it be diagnosed according to Article 15 (atrial tachycardia) or Article 17 (paroxysmal supraventricular tachycardia)? Recommendation: Paroxysmal supraventricular tachycardia should be diagnosed even if the arrhythmia is seen throughout the ECG (Article 17). Atrial tachycardia (Article 15) should be diagnosed in the presence of narrow QRS wave tachycardia with identifiable ectopic P waves. Short PR intervals are common but not always present.
Question 15: Patients with atrial fibrillation or chronic heart failure present with an ECG that demonstrates sagging ST-segment depression, paroxysmal atrial tachycardia with conduction block, or complete heart block with accelerated junctional rhythm. If the history does not specifically mention that the patient is being treated with digoxin, should the diagnosis be Article 70 (digitalis effect) or Article 71 (digitalis toxicity)? Recommendation: Yes. At this time it is appropriate to diagnose the typical ECG manifestations of digitalis effect or intoxication in patients who are likely to be treated with digoxin.