2007 ICD-9-CM Procedure 89.50 Ambulatory cardiac monitoring 89.50 is a specific code that can be used to specify a procedure 89.50 contains 4 index entries View the full Volume 3 89.* hierarchy 89.50 also known as: Analog devices [Holter-type] Index entries containing 89.50: Ambulatory cardiac monitoring (ACM) 89.50 Monitoring cardiac output (by) ambulatory (ACM) 89.50 Holter-type device 89.50 Holter-type device (cardiac) 89.50