 Examples include the intraocular lens, intrastromal corneal ring segment, cochlear implant, tympanostomy tube, and neurostimulator.Cardiovascular medical devices are implanted in cases where the heart, its valves, and the rest of the circulatory system is in disorder.They are used to treat conditions such as heart failure, cardiac arrhythmia, ventricular tachycardia, valvular heart disease, angina pectoris, and atherosclerosis.