At Visit 1, patients eligible at the beginning of HD had 2 mL (2 mg) of tenecteplase instilled into each of the two lumens of the HD catheter. After a dwell time of 1 hour, study drug was withdrawn and all subjects underwent HD. The duration of the HD session was not fixed by the study protocol, but rather by the site's HD practice, physician orders, and individual patient response during the session. Patients who did not experience treatment success at the end of Visit 1 had 2 mL (2 mg) of tenecteplase instilled into each lumen of their catheter as part of the initial treatment course. The treatment was left to dwell for an extended time, until the second HD session at Visit 2 (up to 72 hours later). Patients who received extended-dwell tenecteplase had the treatment withdrawn from their catheter at the beginning of Visit 2. Patients underwent HD as prescribed or to the extent possible.