The Zio Patch heart rate monitor is a key test for anyone suffering from palpitations, arrhythmias, racing heart, lightheadedness, or fainting. This patch detects atrial fibrillation, irregular heartbeats such as PACs and PVCs, heart blocks, and fast/slow heart rates. It is a test that requires two weeks of monitoring. We send the monitor to you and instruct you on how to apply it. After two weeks, mail in the monitor in the prepaid envelope.