What change in ECG can be observed in patients with TCA overdose?

In patients with tricyclic antidepressant (TCA) overdose, the most notable electrocardiogram (ECG) changes include QRS widening and sometimes prolonged PR intervals. QRS widening is particularly significant as it reflects the effects of TCAs on cardiac conduction, especially with their anticholinergic properties and sodium channel blockade, which can disrupt the depolarization process.

Prolonged PR intervals can also occur due to the atrioventricular (AV) conduction system being affected, but it is not as consistently observed as QRS widening in TCA overdose cases.

While QT intervals may also be studied in different settings, in TCA overdose, the trend towards a shortened QT interval is not commonly associated and is not a prominent feature.

Given these considerations, the most relevant observations are that TCA overdose typically presents with both QRS widening and potentially prolonged PR intervals, making the option that includes all these changes appropriate in the context of a comprehensive assessment. Thus, the option indicating all of the changes recognized in the ECG during TCA overdose effectively encapsulates the spectrum of possible findings one might observe in a clinical scenario involving TCA toxicity.