English to French Medical Medical: Cardiology

What would mean "24-hour" in this conetxt?

Any clinically significant disorder of rhythm or conduction requires evaluation by a cardiologist acceptable to the AMS. Such evaluation may include the following, on clinical indication:
(1) resting and exercise electrocardiography;
(2) 24-hour ambulatory electrocardiography;
(3) 2D Doppler echocardiography;
(4) coronary angiography;
(5) electrophysiological investigation.