Different electrocardiographic abnormalities can mimic a heart attack or myocardial infarction.
Simulation of an Anterior Myocardial Infarction
Left Bundle Branch Block
- LBBB can cause poor R wave progression. In the presence of LBBB, there is often a decrease in the amplitude of R waves to the mid precordium in the absence of a septal infarct.
- QS complexes are often seen in the right precordial leads in uncomplicated LBBB, and they may even extend as far out as V5 or V6.
- Non infarctional Q waves may be seen in aVL.
- The electrical basis for the appearance of q waves is that LBBB] causes a loss of the normal septal R waves in the right precordial leads. The septum is no longer being depolarized from left to right as it normally does because of the delay in conduction down the left bundle. Therefore, there is a loss of the early R wave.
- There can occasionally be Rs complexes in V1. These unanticipated initial positive forces are due to early RV depolarization and may actually mask the q waves (i.e. loss of initial septal forces) that accompany an anteroseptal MI.
Poor R Wave Progression
Poor R wave progression can mimic an anterior myocardial infarction.