Narrowing of the Pulmonary valve. This may be often associated with other heart defects. The ensuing impairment is in blood flow from the right atrium into the Pulmonary artery during systole. A systolic murmur ensues.
Because there is impaired blood flow into the lungs, symptoms will usually be such of insufficient oxygenation of tissues, resulting in cyanosis, weakness, fainting etc. The solution of the problem is surgical correction.