The application 'Heparin Heuristics'  is  based on the experience gained while providing anaesthetic care to over 1,000 patients undergoing catheter ablation for atrial fibrillation. It was developed during a clinical trial entitled "A Heuristic Approach to determine the optimal method of Heparin Dosing and Reversal in all Patients Undergoing Anaesthesia for Catheter Ablation for Atrial Fibrillation (CA-AF)", ANZCTR  Trial Id: ACTRN12618001489280 (https://www.anzctr.org.au ) and approved by the Ramsay Human Ethics Committee: Clinical trial number 18/38 9th October 2019.