Patent foramen ovale and atrial septal defect closure is a routine procedure to close holes in the upper chambers of the heart. Patent foramen ovale (PFO) is a congenital cardiac lesion which is generally asymptomatic and affects up to a quarter of the population.The foramen ovale is a hole in the wall between the left and right atria of every human fetus. This hole allows blood to bypass the fetal lungs. Percutaneous closure of a patent foramen ovale (PFO) reduces the risk of recurrent cryptogenic stroke specifically in younger patients. As the heart develops in the foetus, the primum and secundum septa grow and overlap. At birth, the PFO should close. Patient characteristics. If you have a PFO and low blood oxygen levels or an unexplained stroke, you may need a procedure to close the hole. RoPE = risk of paradoxical embolism; TIA = transient ischemic attack; VTE = venous thromboembolism.