A 67-year-old man complains of dyspnea on exertion, attacks of retrosternal pain, dizziness. He has no history of rheumatism. Objectively: pale skin, acrocyanosis. There are crackles in the lower lungs. There is systolic thrill in the II intercostal space on the right, coarse systolic murmur conducted to the vessels of neck. BP-130/90 mm Hg, heart rate - 90/min., regular rhythm. The liver extends 5 cm from under the edge of costal arch, shin edemas are present. Specify the suspected valvular defect: