Foramen ovale insufficiency can cause stroke, which in turn can lead to weakness in the left limb. Foramen ovale insufficiency is a congenital heart defect. The foramen ovale is the physiologic passageway for the atrial septum of the heart during embryonic life, and in most people it fuses to form a permanent atrial septum in the first 5-7 months of life, or if it does not fuse, then it forms a patent foramen ovale. In patients with a small foramen ovale, the shunt flow between the left and right atria is small and most often asymptomatic. When the foramen ovale is large, there is a significant shunt of blood, and complications such as stroke, migraine, and peripheral arterial embolism can occur, leading to symptoms. Patients with patent foramen ovale need to go to the hospital in time for treatment when they experience weakness of the left side of the limbs and undergo patent foramen ovale blockage if necessary to prevent recurrence of stroke.