The study will recruit 20 patients divided into; 10 patients undergoing PFO/ASD occlusion and 10 patients undergoing LAA occlusion. EPC will be measured on the day of the device implantation, day 0 and prior to discharge on day 1, then on subsequent follow up appointments on days (3-4) and (7-8). Blood samples of 3-5ml will be taken to allow flow cytometric analysis for EPCs.