when has patient 22315 received the last opn/oth rep aort vlv-tis?
select procedures_icd.charttime from procedures_icd where procedures_icd.icd9_code = ( select d_icd_procedures.icd9_code from d_icd_procedures where d_icd_procedures.short_title = 'opn/oth rep aort vlv-tis' ) and procedures_icd.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 22315 ) order by procedures_icd.charttime desc limit 1