instruction: what are the maximum total hospital costs involving a procedure called a tiss adj to valv ops nec?
response: SELECT MAX(t1.c1) FROM (SELECT SUM(cost.cost) AS c1 FROM cost WHERE cost.hadm_id IN (SELECT procedures_icd.hadm_id FROM procedures_icd WHERE procedures_icd.icd9_code = (SELECT d_icd_procedures.icd9_code FROM d_icd_procedures WHERE d_icd_procedures.short_title = 'tiss adj to valv ops nec')) GROUP BY cost.hadm_id) AS t1