After the hospital stay, all participants will attend five study visits that will occur 1 week and 1, 3, 6, and 12 months after the injection procedures. At all study visits, participants will undergo an electrocardiogram, lab tests, and a review of adverse health events. On all but the last study visit, participants will have cardiac markers assessed, and they will wear a 24-hour Holter monitor to track heart activity. At the last three visits, participants will also complete quality of life questionnaires. All participants will then receive four follow-up telephone calls that will occur 2, 3, 4, and 5 years after the injection procedures.