The primary objective of this study is to determine the impact of the shock wave application in renal transplant patients with diagnosis of erectile dysfunction. Secondary objectives are to assess the effects of therapy on quality of life and depression.

It is expected that with the study is defined the usefulness of the therapy and the dissemination of knowledge generated for change in clinical management in renal transplant patients with erectile dysfunction.

The Renal Transplant Unit, performs about 230 kidney transplants per year and has a screening service for registration of candidates for renal transplantation, interviewing about 70 patients a month. Since the potential and likely benefits of extracorporeal shock wave therapy in these patients as well as the anticipation of mild side effects, there is no reason for refusal to participate in the study.

Patients who meet the inclusion criteria will be divided into 2 groups using a randomization table created by computer. Patients will be followed for 2 years.

The study procedure and monitoring will be performed on an outpatient basis.

Patients are divided into a group of extracorporeal shockwave (ESWT) treatment and placebo in a ratio of 1: 1 using a table of random numbers generated by computer.

The ESWT protocol is protocol-based suggested by Vardi et al. 6. Patients will undergo a 2 treatment sessions per week for 3 weeks.

The penis is pulled manually, and shock waves are applied throughout the penile shaft (except the glans) and the crura bilaterally. The duration of each ESWT session will be approximately 10 minutes and 2000 shocks will be applied per session with an intensity of energy of 1 mJ / mm 2. The volume of penile tissue exposed to shock waves at each site will be cilyndric (diameter: 18 mm, height 100 mm). No local or systemic analgesia is required during the procedure.

To placebo therapy will be used the same device. The effective probe will be replaced by a similar one that emits zero energy during each treatment. Local application generates noise and a feeling of popping at the application site which will also be experienced by patients in the placebo group being impossible for the patient to discern which treatment group belongs.

Penile ultrasound Doppler and drug erection will be performed before therapy and after treatment to evaluate the results.

The diameter of the cavernous arteries is measured before and after intracavernosal injection application 20 mcg alprostadil (Caverject ®). In addition, vascular disorders, or stenotic atheromatous lesions will be investigated. The systolic and diastolic velocities of the cavernous arteries are evaluated 5,10 and 15 minutes after drug injection.

After obtaining the patient signed informed consent , will be included in the study. Laboratory tests will be held at the Hospital Laboratory.

Studied variables

The following parameters will be studied during the initial evaluation and follow-up:

1. Clinical

   Quality of life questionnaire -WHO QOL (World Health Organization - Quality of Life) Sexual questionnaire IIEF (International Index of Erectile Function) Comorbidities such as hypertension, diabetes and cardiovascular disease Smoking

2. Laboratory

   Total testosterone, free testosterone, progesterone, albumin, SHBG, FSH, LH, prolactin, complete blood count, urea, creatinine, total cholesterol and fractions, triglycerides, T3, T4F and TSH.

3. Imaging tests

Ultrasound Doppler penile before and 3 months after treatment.

- Calculation sample

To define the sample size, the investigators must take into account: data variability (within each group) and the difference the investigators want to observe the parameters to be studied before and after treatment, beyond the level of significance and power of the test.

The investigators will assume that the data follow a normal distribution and will use the paired t-test methodology, considering that the same patients will be evaluated in both conditions.

The level of significance that work is 5%. Suitable power will be considered to be greater than 80%.

The investigators observe a difference to 5 points required amount of samples is very small, whereas only 3 patients t-test. for the non-parametric test we consider a sample of 4 patients.

Inclusion Criteria:

• Male patients between 40 and 70 years
• Kidney transplant for at least 6 months
• Erectile dysfunction (ED) for at least 6 months.
• Patients with IIEF score <21
• Functioning kidney graft.

Exclusion Criteria:

• ED because of known endocrine disease (e.g., hypogonadism, hypothyroidism)
• ED due to drug treatment (androgen deprivation therapy, for example)
• ED due to neurological disease (spinal cord injury, for example)
• ED due to structural abnormality of the penis
• History of radical prostatectomy or other pelvic surgery
• History of pelvic irradiation
• penile implant
• coagulopathies or on anticoagulants