This discussion of arrhythmia terminology attempts to classify rhythm disorders for which surgical therapy may be necessary. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery, for the purpose of establishing a unified reporting system. Efforts were made to include all relevant nomenclature categories, using synonyms where appropriate. Extant surgical ablative procedures, detailed methods of pacemaker insertion, and AICD technology are discussed. A comprehensive database set is presented that is based on a hierarchical scheme. Data are entered at various levels of complexity and detail, which can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented, which will allow for data sharing and will lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.