QUANG - Are you missing MI

Duy Quang - YC (2007-2013)

Are You Missing an MI?

Duy Quang - YC (2007-2013)

• Most physicians are very comfortable with the classic electrocardiographic (ECG) findings of ST changes, T wave inversions, and Q waves in myocardial ischemia or infarction. However, the subtle myocardial infarction (MI) may be easily overlooked, especially in patients with underlying ECG abnormalities. The tracing shown demonstrates ischemia with an underlying left bundle branch block (LBBB), an abnormality that typically excludes the diagnosis of an MI. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing shows a LBBB with a MI. LBBBs make elevations or depressions in the precordial leads unreliable, often masking an MI. A LBBB can be identified by the widened QRS, notched R wave in V6, and rS complex in V1. Additionally, the T waves should be opposite the terminal deflection of the QRS complex. This tracing demonstrates biphasic and inverted T waves in leads III and aVF (black arrows) that are in the same terminal deflection as the QRS complex, suggesting inferior ischemia. These findings are specific, but not particularly sensitive for ischemia or infarction. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing is another example of a LBBB with a likely prior and ongoing MI. The Q waves in I and V6 (black arrows) and the notched S wave in V2 and V3 (red arrow) suggest prior MI. A notching in the first 0.04 seconds in duration of the ascending limb of the S wave in lead V3 or V4 in a tracing with a LBBB suggests a prior MI and is referred to as Cabrera's sign. The biphasic T waves in leads V2, V3, and V4 with a component in parallel to the terminal deflection of the QRS suggests current ischemia (blue arrows). Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing demonstrates a right bundle branch block (RBBB) with an acute MI. Similar to a LBBB, T waves should be opposite the terminal deflection of the QRS complex. A RBBB can be identified by a widened QRS, an rSR' pattern in V1, and a slurred s wave in the qRs of I and V6. This tracing shows replacement of the rSR' pattern with a qR in V1, V2, and V3 (black arrows), which is pathologic if seen past V2. Upright T waves are seen parallel to the terminal deflection of the QRS complex in V2, V3, and V4 (blue arrows). ST-segment elevations are also seen in V2, V3, and V4 (red arrows). These findings all suggest anterior-septal ischemia or infarction. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• Ventricular paced rhythms, like bundle branch blocks, are often not interpretable for cardiac ischemia. In this tracing, there is complete heart block with a ventricular paced rhythm. ST elevations can still be appreciated in the inferior and lateral leads (black arrows) with concomitant depressions in the anterior leads (blue arrows) consistent with infero-postero-lateral ischemia. Significant elevations in the inferior or right precordial leads and ST depression or T wave inversions in leads with QS or rS complexes suggests ischemia. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing is another example of a paced rhythm with underlying MI. The rhythm strip shows both A-V sequential pacing and A-sensed V-paced rhythms. There are significant elevations in the inferior leads (black arrows), with reciprocal depressions (blue arrows) suggesting an inferior MI. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing shows bigeminal premature ventricular complexes (PVCs) with underlying ischemia. There are ST elevations in leads I and aVL (black arrows) with depressions in III and aVF (blue arrows) consistent with an antero-lateral MI. Because of the bigeminal PVCs, these changes are only appreciated every other beat and could be easily overlooked due to the PVC morphology. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing is another example of ischemia with ventricular premature beats (VPBs) in a bigeminal pattern. The alternating sinus beats show ST elevations in the inferior leads (black arrows) with reciprocal depressions in the antero-lateral leads (blue arrows) consistent with inferior ischemia. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing demonstrates an ongoing or recent anterior myocardial ischemia in a patient with chest pain 2 days earlier and only mildly elevated cardiac markers. There are significant T wave inversions in the anterior precordial leads (black arrows) without Q waves or ST depressions/elevations. Prominent T wave inversions can also be caused by central nervous system disease, apical hypertrophic cardiomyopathy, stress cardiomyopathy, and intermittent right ventricular pacing or LBBB. Other findings on this tracing are mild PR and QT prolongation and left ventricular hypertrophy. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing demonstrates lateral wall ischemia that could easily be confused with normal variant early repolarization. There are ST elevations in V4, V5, and V6 (black arrows) with subtle reciprocal depressions in V2 and V3 (blue arrows). Early repolarization may be found in a similar lead distribution, but there is usually a more prominent concave upward component with larger T waves. There are never reciprocal depressions with early repolarization. The tracing also shows some incidental Q waves in II and aVF suggesting an older MI. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing shows myocardial ischemia from occlusion of the left anterior descending artery. There are T wave inversions in leads V2, V3, and V4 (black arrows) with biphasic T waves in V5, I, and aVL (blue arrows). This pattern is referred to as Wellens’ syndrome or Wellens' T waves which is caused by critical narrowing of the proximal left anterior descending artery. Tracings must show progressive deep T wave inversions in leads V2 and V3, a steep 60°-90° slope to the T waves, no discrete ST-segment elevations, and no loss of the precordial R waves. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing demonstrates an inferior MI with low limb lead voltages. Low voltages can make the findings of an MI much more difficult to detect. In the inferior leads there are slight ST elevations (black arrows) and T wave inversions (blue arrows) with reciprocal depressions in aVL (red arrow). Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• What is the ECG abnormality? Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing demonstrates an infero-lateral MI. There are ST elevations in the inferior and lateral leads (black arrows) with reciprocal depressions in leads aVL, V1, and V2 (blue arrows). Occlusion of the right coronary artery or the left circumflex artery can cause infero-lateral ischemia. A right coronary artery occlusion is more likely when the ST elevations in lead III are greater than lead II and when there are no elevations in lead I. Tracing courtesy of ECG Wave-Maven.

Duy Quang - YC (2007-2013)

• This tracing is another example of an inferior MI from a right coronary artery lesion over a circumflex. The ST elevation in lead III (black arrow) is greater than in lead II (blue arrow) and there is no elevation in lead I (red arrow). Tracing courtesy of ECG Wave-Maven.