Which test measures the electrical activity of the heart over a 24-hour period?

The Holter monitor is a device specifically designed to continuously record the electrical activity of the heart over a 24-hour period or longer. This test is particularly useful for detecting irregular heart rhythms (arrhythmias) that may not be present during a standard electrocardiogram (ECG) due to the brief nature of that test.

Patients wear the Holter monitor, which consists of electrodes attached to the chest that connect to a portable recording device. This allows for continuous monitoring of the heart's electrical signals while the person goes about their daily activities, providing a more comprehensive look at heart activity over time.

In contrast, an echocardiogram uses ultrasound waves to create images of the heart's structure and function, focusing on its physical properties rather than its electrical activity. An electrocardiogram provides a snapshot of heart activity at a single moment in time, making it less effective for ongoing monitoring. A stress test typically evaluates heart function under physical exertion, but does not measure electrical activity continuously throughout the day.

Therefore, the Holter monitor stands out as the accurate choice for a test that measures the electrical activity of the heart over an extended period.