2007 ICD-9-CM Procedure 35.42 Creation of septal defect in heart 35.42 is a specific code that can be used to specify a procedure 35.42 contains 7 index entries View the full Volume 3 35.* hierarchy 35.42 also known as: Blalock-Hanlon operation Index entries containing 35.42: Blalock-Hanlon operation (creation of atrial septal defect) 35.42 Creation -- see also Formation interatrial fistula 35.42 Formation interatrial fistula 35.42 septal defect, interatrial 35.42 Operation Blalock-Hanlon (creation of atrial septal defect) 35.42 Production -- see also Formation and Creation atrial septal defect 35.42 Septectomy atrial (closed) 35.41 open 35.42