Tachycardia (fast heart beat) can be related to thyroid issues. The thyroid controls the electrical activity of the heart. You most likely could benefit from the use of iodine added to your supplement regimen. Get Dr. David Brownstein's book, "Iodine: Why You Need It, Why You Can't Live Without It". You start with low dose iodine/iodide of 12.5 mg and work up. Most people in our modern world are iodine deficient because of the depleted soil as well as the addition of bromides to our diet (used in commercial bread making).