CPT code 33645 denotes surgical closure of a sinus venosus atrial septal defect, either by direct suture or patch, and may be performed in patients with or without anomalous pulmonary venous drainage. This code captures a specialized cardiothoracic procedure used to correct a congenital interatrial communication that can have significant clinical consequences if left untreated. Nationally, accurate coding for this repair supports clinical quality measurement, appropriate reimbursement for complex cardiac surgery, and tracking of congenital heart defect interventions across hospital systems.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context and procedural scope, payer coverage considerations, and typical billing elements associated with this inpatient surgical service. The publication provides benchmarks and policy-relevant summaries where available, highlights common billing modifiers and payer interactions provided in the input, and outlines areas where additional documentation or coding specificity may affect claims processing. Data not available in the input is identified for items such as associated taxonomies, specific ICD-10 diagnoses, and related codes.