What is indicated when pathologic Q waves are present on an ECG?

The presence of pathologic Q waves on an electrocardiogram (ECG) indicates necrosis of heart cells, which typically occurs as a consequence of a myocardial infarction (heart attack). Pathologic Q waves are wider and deeper than normal Q waves and represent an area of infarcted myocardium that has undergone irreversible damage.

When heart cells are necrotic, they do not conduct electrical impulses effectively, which alters the shape of the ECG waveform. This change is a hallmark of myocardial injury that has progressed to the point of causing cellular death. Recognizing pathologic Q waves is crucial for diagnosing prior heart attacks and assessing the extent of damage to the heart muscle.

In contrast, reversible ischemia would not cause pathologic Q waves because the myocardial tissue is still viable, and normal myocardial function would present with a different ECG morphology. Transient angina also does not cause pathological Q waves since it involves temporary reductions in blood flow without resulting in cell death. Understanding these distinctions is vital for interpreting ECG findings and determining appropriate patient management in cardiovascular care.