The amplitude and morphology of the QRS complex provides diagnostic information obtained from which of the following?

The amplitude and morphology of the QRS complex are key components of the electrocardiogram (ECG or EKG). The QRS complex represents ventricular depolarization, and its characteristics are crucial for evaluating cardiac function and diagnosing various heart conditions.

A normal QRS complex indicates that the electrical activity is following the expected pathway through the heart's ventricles. Any changes in amplitude or morphology can reflect underlying issues such as hypertrophy, conduction blocks, or ischemia. For instance, a wide QRS complex may suggest a delay in conduction pathways, while a tall or peaked QRS could indicate ventricular hypertrophy.

In contrast, blood tests, X-rays, and CT scans provide different types of diagnostic information that are not directly related to the electrical activity of the heart. Blood tests measure biochemical markers, imaging studies like X-rays and CT scans focus on anatomical structures and may reveal physical abnormalities but do not assess the heart's electrical function. Thus, the correct answer highlights the specialized utility of the electrocardiogram in cardiac diagnostics.