A pledge may be established over all or part of the leases of an immovable, including those not yet in existence, without the necessity of specific description of the leases in the contract establishing the pledge. If the pledge is established over leases not yet in existence, the pledge encumbers future leases as they come into existence. The pledge has effect as to third persons, even with respect to leases not in existence at the time of formation of the contract establishing the pledge, from the time that the contract establishing the pledge is recorded in the manner prescribed by law.
La. C.C. § 3171