Hi! Thank you for your question and welcome to HCM!
is known to have a side effect of tachycardia
or rapid heart beat presenting in ~5% of patients. It also has a potentially serious side effect of cardiac dysrhythmias (irregular heartbeats), which may be the one that you experienced.
I would suggest that you see your physician immediately so that he/she can adjust the dosage appropriately or shift you to a new regimen as needed. He/she may also have to run some tests (including an ECG) on you to check your heart and other exams to check other parts of your body affected by vyvanse.
I hope I was able to answer your query. If you have any further question, please do not hesitate to contact me (http://doctor.healthcaremagic.com/doctors/dr-rene-gerard-cruz-galera-jr/66134). Take care!