Patients with patent ductus arteriosus should avoid running. The condition can cause a left-to-right shunt, increasing pulmonary circulation and the volume of blood returning to the left heart system, which in turn leads to increased left heart workload and potential left heart dysfunction. In adults with patent ductus arteriosus, the clinical symptoms vary depending on the size of the shunt. Those with very small shunts may exhibit no subjective symptoms clinically. Patients with moderate shunts often experience symptoms such as fatigue, palpitations after activity, shortness of breath, and chest tightness. Those with large shunts, often accompanied by severe secondary pulmonary hypertension, may experience a right-to-left shunt, leading to cyanosis and very severe clinical symptoms.