Comparison of Participants Who Received a CanGaroo® Envelope, TYRX™ Envelope, or no Envelope During CIED Implantation

Inclusion Criteria: 1. Participants who previously underwent one or more prior CIED implantations utilizing a CanGaroo® envelope, TYRX™ envelope, or no envelope and are returning for a CIED change-out or revision procedure at least 4 months or longer from their prior procedure. 2. The following possible scenarios would be eligible for enrollment: a. One prior CIED Implant: i. No envelope ii. CanGaroo® envelope iii. TYRX™ envelope b. Multiple prior CIED Implants (envelope type should remain the same for each participant throughout their implant history): i. No envelope → no envelope ii. No envelope → CanGaroo® envelope iii. No envelope → TYRX™ envelope iv. CanGaroo® envelope → CanGaroo® envelope v. TYRX™ envelope → TYRX™ envelope vi. No envelope → CanGaroo® envelope → CanGaroo® envelope vii. No envelope → no envelope → CanGaroo® envelope viii. No envelope → TYRX™ envelope → TYRX™ envelope ix. No envelope → no envelope → TYRX™ envelope 3. Participants aged 18 years or older at time of enrollment. 4. Participant is able and agrees to provide written informed consent and use of PHI. 5. Participants for whom prior CIED implant history information can be obtained. Exclusion Criteria: 1. Active infection involving the CIED implant site (clinical diagnosis of an active infection at the time of change-out/revision procedure). 2. Participants under the age of 18 at time of enrollment. 3. Participants with a history of multiple prior CIED implants over time using more than one type of envelope will be excluded as well as participants with a history of one type of envelope use, but the current pocket does not have an envelope. Scenarios that would be excluded: 1. CanGaroo® envelope → TYRX™ envelope 2. TYRX™ envelope → CanGaroo® envelope 3. CanGaroo® envelope - no envelope 4. TYRX™ envelope → no envelope 5. No envelope → CanGaroo® envelope → no envelope 6. No envelope → TYRX™ envelope → no envelope 7. No envelope → CanGaroo® envelope → TYRX™ envelope 8. No envelope → TYRX™ envelope → CanGaroo® envelope 9. CanGaroo® envelope → no envelope → TYRX™ envelope 10. TYRX™ envelope → no envelope → CanGaroo® envelope 11. CanGaroo® envelope → TYRX™ envelope → no envelope 12. TYRX™ envelope → CanGaroo® envelope → no envelope 13. CanGaroo® envelope → CanGaroo® envelope → no envelope 14. TYRX™ envelope → TYRX™ envelope → no envelope 4. Participants undergoing a change-out or revision procedure less than 4 months from their prior procedure.