A Positive Intracavernous Injection Test Implies Normal Veno-Occlusive but Not Necessarily Normal Arterial Function: A Hemodynamic Study

During impotence evaluations a positive intracavernous injection test has been presumed to signify normal erectile hemodynamics. This premise was tested by obtaining hemodynamic data in 80 patients 17 to 65 years old with positive injection tests: patients achieved maximal circumference responses and equilibrium intracavernous pressures of 80 mmHg or more (range 80 to 136) sustained for 30 minutes or longer. Corporeal veno-occlusive testing revealed that flow-to-maintain (0.5 to 3 ml. per minute) and pressure decay (0 to 47 mmHg) values as well as pharmaco-cavernosography findings (absent or minimal contrast medium in venous structures in 92% of the cases) were all consistent with low outflow erection states. Arterial testing revealed right and/or left cavernous systolic arterial blood pressures always at 80 mmHg or more, consistent with a prerequisite cavernous artery pressure value for a positive injection test. Systemic-cavernous systolic arterial blood pressure gradients were 0 to 24 mmHg, 25 to 34 mmHg and 35 mmHg or more in 47 (59%), 18 (22%) and 15 (19%) patients, respectively. Large systemic-cavernous pressure gradients suggested the presence of arterial occlusive disease. In 8 patients with positive injection tests and gradients of 35 mmHg or more pharmaco-arteriography revealed hemodynamically significant arterial occlusions. In conclusion, hemodynamic data in selected patients with positive injection tests revealed low outflow erection states, threshold cavernous artery pressures and disparities in systemic-cavernous systolic pressure gradients that suggested arterial disease in 19% of the cases. The erectile response in a positive test is equal to or greater than a threshold response, not always the maximum response as determined by the systemic blood pressure. A positive intracavernous injection test did not necessarily signify normal erectile hemodynamics.