The study began after a previous, randomized, clinical trial of testosterone therapy in men was stopped prematurely "due to adverse cardiovascular events raising concerns about testosterone therapy safety." Prostate cancer
Testosterone in the presence of a slow-growing prostate cancer is assumed to increase its growth rate. However, the association between testosterone supplementation and the development of prostate cancer is unproven. Nevertheless, physicians are cautioned about the cancer risk associated with testosterone supplementation.Testosterone may accelerate pre-existing prostate cancer growth in individuals who have undergone androgen deprivation. It is recommended that physicians screen for prostate cancer with a digital rectal exam and prostate-specific antigen (PSA) level before starting therapy, and monitor PSA and hematocrit levels closely during therapy.Ethnic groups have different rates of prostate cancer. Differences in sex hormones, including testosterone, have been suggested as an explanation for these differences. This apparent paradox can be resolved by noting that prostate cancer is very common. In autopsies, 80% of 80-year-old men have prostate cancer. Pregnancy and breastfeeding
Testosterone is contraindicated in pregnancy and not recommended during breastfeeding. Androgens like testosterone are teratogens and are known to cause fetal harm, such as producing virilization and ambiguous genitalia. Interactions
5α-Reductase inhibitors
5α-Reductase inhibitors like finasteride and dutasteride can slightly increase circulating levels of testosterone by inhibiting its metabolism. However, these drugs do this via prevention of the conversion of testosterone into its more potent metabolite dihydrotestosterone (DHT), and this results in dramatically reduced circulating levels of DHT (which circulates at much lower relative concentrations).
Double balloon dilation involves catheters inserted in the left and right femoral vessels placed parallel to stenotic lesions and inflated simultaneously. The two balloon technique creates a substantial decrease in pressure gradients by achieving greater dilation from the use of two smaller balloons as opposed to a single large balloon. Balloons are inflated and deflated repeatedly to reduce the resistance of the vessels to inflation. Once the balloons are removed an end-hole catheter is passed over the wires to ensure a moderate systemic pressure drop occurs and then a stent is placed. Substantial pressure drops are common following single balloon dilation procedures. Hydrophilic catheter treatments can also be used through placement of the catheter through the femoral veins to access the stenosis in the vena cava to measure haemodynamic and angiography. Angiography allows for visualisation of the stenosis in the vena cava and measurements of the pressures and length of narrowing can be obtained from the technique, including the narrowest diameter of the stenosis. Balloon angioplasties can also be performed in the narrowed vena cava using Sterling balloons. Dilations are also performed with higher pressure Dorado balloons, using the same wire as the Sterling balloon. Sustained results of increased flow and significant reduction in obstructions following stent implantation occurs from balloon angioplasty treatments. Epidemiology
Congenital stenosis of the vena cava is a rare congenital heart disease affecting 0.7 - 8.7% of the population. Vena cava anomalies are very rare and arise from incorrect development in the foetal heart.