Final answer:
The Valsalva maneuver is the procedure that forces a patient to strain against a closed glottis to manage stable narrow-complex tachycardia, potentially slowing the heart rate through increased intrathoracic pressure.
Step-by-step explanation:
The procedure used in the management of stable narrow-complex tachycardia that forces a patient to strain a closed glottis is known as the Valsalva maneuver. This maneuver is performed by asking the patient to attempt to exhale forcefully with the airway closed, creating increased pressure in the chest cavity. This temporarily affects the blood flow in the heart and vessels, stimulating the vagus nerve and potentially slowing down the heart rate. It is a non-invasive method that can be attempted before escalating to other interventions such as medication or cardioversion.