Certified Medical-Surgical Registered Nurse Practice Exam 2025 - Free Practice Questions and Study Guide

Tall, tented T waves on an ECG are characteristic changes associated with hyperkalemia, which refers to elevated levels of potassium in the blood. Potassium plays a crucial role in maintaining the electrical stability of the heart. When potassium levels are high, the normal repolarization process is altered, leading to the characteristic tall, tented appearance of the T waves. This occurs due to the prolonged action potential, which affects the way the heart muscles contract and relax.

In contrast, the other conditions mentioned impact the ECG differently. For instance, hypokalemia, or low potassium levels, typically manifests as flattened T waves and the presence of U waves. Hypocalcemia can lead to prolonged QT intervals and a variety of other changes, while hypercalcemia may shorten the QT interval and alter T wave morphology but does not produce tall, tented T waves. Thus, the presence of tall, tented T waves is a key indicator of hyperkalemia, allowing healthcare providers to identify and address this potentially life-threatening condition promptly.

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