Final answer:
The murmur called Graham Steell murmur is associated with pulmonary insufficiency due to pulmonary hypertension which occurs when pulmonary artery systolic pressure exceeds 70 mmHg.
Step-by-step explanation:
When pulmonary artery systolic pressure exceeds 70 mmHg, the resulting dilation of the pulmonic annulus can lead to a regurgitation jet of high velocity. This phenomenon is responsible for the murmur known as the Graham Steell murmur. The pulmonary semilunar valve, or the pulmonic valve, consists of three endothelial flaps reinforced with connective tissue. Normally, this valve prevents the backflow of blood, but in pulmonary hypertension, the increased pressure can lead to pulmonary insufficiency, and thus, a regurgitation of blood may occur. When the valve cannot close adequately, disrupted blood flow leads to a heart murmur, which can be identified by auscultation using a stethoscope.
The Graham Steell murmur is specifically associated with pulmonary insufficiency due to pulmonary hypertension, and it is distinct from other heart murmurs such as the Austin Flint murmur, Rivero-Carvallo sign, or Lillehei-Kaster murmur, which are related to different cardiac conditions.