Question 59

Changes in the ECG are typically used for diagnosis of abnormal cardiac rhythm.

This statement is not mentioned in the passage, which focuses on the mechanics of the electrocardiogram (ECG) and the heart's electrical activity without explicitly linking changes in the ECG to the diagnosis of abnormalities.

A) Changes in the ECG are typically used for diagnosis of abnormal cardiac rhythm.

This option is correct as it is not referenced in the provided extract. While the passage discusses the ECG and its relation to heart activity, it does not address the use of ECG changes for diagnosing abnormal cardiac rhythms.

B) The signal has a characteristic record called the electrocardiogram.

This statement is accurate according to the passage, which clearly defines the electrocardiogram (ECG) as the record of the heart's rhythmic electrical signals. Thus, it is a detail included in the text.

C) The "wave of excitation" starts at the SA node.

This statement is also accurate and explicitly mentioned in the extract. It describes the initiation of the heart's electrical impulses, confirming that the SA node is the source of the "wave of excitation."

D) The "wave of excitation" spreads through the heart wall and is accompanied by electric changes.

This option is a true statement found in the passage. It describes the propagation of electrical activity throughout the heart wall, including the associated electrical changes, making it a detail included in the text.

Conclusion

The correct answer is A, as it is the only statement not found in the passage. Options B, C, and D are detailed elements of the ECG's function and the heart's electrical activity, clearly supported by the provided text. Thus, A stands out as the only assertion that lacks backing from the passage.