Arterial erectile dysfunction (ED) refers to the obstructive lesions of the aorta, iliac artery, pudendal artery and its branches that hinder normal blood perfusion in the penis, thereby causing ED. In addition to ED, patients with this condition may also experience intermittent claudication, difficulty walking fast, and leg pain. The causes of this disease could be vascular occlusive arteritis, arteriosclerosis, or embolism. Some patients' arterial ED might likely result from thrombosis caused by varicose veins in the lower extremities partially blocking the aforementioned arteries.
We know that apart from supplying blood to the penis, the internal iliac artery mainly supplies blood to the thigh and buttocks regions. When there is hardening or embolism of the large arteries, it will lead to the "pelvic steal" syndrome. Normally, there are sufficient collateral circulations within the pelvis to compensate for the blockage caused by arteriosclerosis, so patients usually report no issues with morning erections, no problems with initiating sexual activity, and even no issues with penetration. However, once active pelvic thrusting begins, the body's demand for additional blood supply increases sharply due to muscle movement, correspondingly reducing or interrupting blood flow to the penis, which leads to a rapid decline in penile erection. Pelvic steal syndrome is also known as pelvic shunting syndrome, and this might also be what is colloquially referred to as "withering upon encountering stimulation."
The core issue for these patients is not obtaining an erection but maintaining one. This steal phenomenon does not manifest during rest, so a simple test to diagnose the shunting syndrome would be to have the patient do a few minutes of exercise involving the buttocks and legs, and measure the penile and upper arm arterial blood pressure before and after the exercise. Some patients' penile artery index decreases by at least 10% after exercise, whereas this index remains unchanged in normal individuals both before and after exercise. If, for some reason, surgical correction of the vascular embolism is not possible, then the man could adopt a passive position during intercourse (such as female on top or side-lying positions), which might partially address this issue.