A system for implanting an implantable medical device (IMD) within a patient may include an IMD including an attachment member, and a delivery catheter including at least one tethering device having at least a portion positioned within a restrainer. The tethering device(s) is configured to removably tether to the attachment member of the IMD. The restrainer is configured to maintain the tethering device(s) in alignment along a delivery path of the delivery catheter.