PANCE Blueprint Genitourinary (5%)

Erectile dysfunction (Lecture)

Patient will present as → a 60-year-old man who presents to your clinic for evaluation of erectile dysfunction. His wife died 5 years ago and he would like to start dating again. He denies having any life stressors. He reports having no morning or night-time erections. His past medical history includes hyperlipidemia managed with medication and pre-diabetes managed with an active lifestyle and diet.

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Erectile dysfunction is the recurring inability to achieve and maintain an erection sufficient for satisfactory sexual performance

  • It is thought that up to half of all men in the United States between the ages of 40 and 70 have some form of erectile dysfunction. Prevalence increases with age

Risk factors

  • The most important risk factors are those that contribute to atherosclerosis (e.g., HTN, smoking, hyperlipidemia, diabetes)
  • Medications—antihypertensives (may indirectly lower intracavernosal pressure by virtue of lowering systemic BP)
  • Hematologic—sickle cell disease
  • History of pelvic surgery or perineal trauma
  • Alcohol abuse
  • Any cause of hypogonadism/low testosterone state, including hypothyroidism
  • Congenital penile curvature

The major organic causes of ED are

  • Vascular disorders
  • Neurologic disorders
  • Psychological
  • Hormonal
  • Drugs

The most common vascular cause is atherosclerosis of cavernous arteries of the penis, often caused by smoking and diabetes. Atherosclerosis and aging decrease the capacity for dilation of arterial blood vessels and smooth muscle relaxation, limiting the amount of blood that can enter the penis. Veno-occlusive dysfunction permits venous leakage, which results in an inability to maintain an erection.

  • Priapism: usually associated with trazodone use, cocaine abuse, and sickle cell disease, may cause penile fibrosis and lead to ED by causing fibrosis of penile veins that interfere with drainage.
  • Neurologic causes: Include stroke, partial complex seizures, multiple sclerosis, peripheral and autonomic neuropathies, and spinal cord injuries. Diabetic neuropathy and surgical injury are particularly common causes.
  • A psychological cause should be suspected in young healthy men with abrupt onset of ED, particularly if onset is associated with a specific emotional event or if the dysfunction occurs only in certain settings. A history of ED with spontaneous improvement also suggests psychologic origin (psychogenic ED). Men with psychogenic ED usually have normal nocturnal erections and erections upon awakening, whereas men with organic ED often do not.
  • Complications of pelvic surgery (eg, radical prostatectomy [even with nerve-sparing techniques], radical cystectomy, transurethral resection of the prostate, rectal cancer surgery) are other common causes. Other causes include hormonal disorders, drugs, pelvic radiation, and structural disorders of the penis (eg, Peyronie disease). Prolonged perineal pressure (as occurs during bicycle riding) or pelvic or perineal trauma can cause ED.
  • Any endocrinopathy or aging associated with testosterone deficiency ( hypogonadism) may decrease libido and cause ED. However, erectile function only rarely improves with normalization of serum testosterone levels because most affected men also have neurovascular causes of ED.

Detailed history and examination, including a digital rectal examination and neurologic examination. Assess for signs of PAD

  • Laboratory tests—Obtain a CBC, chemistry panel, fasting glucose, and lipid profile
  • If there is hypogonadism or loss of libido, order serum testosterone, prolactin levels, and thyroid profile
  • Nocturnal penile tumescence—If normal erections occur during sleep, a psychogenic cause is likely. If not, the cause is probably organic.
  • Consider vascular testing—Evaluate arterial inflow and venous trapping of blood. Tests include intracavernosal injection of vasoactive substances, duplex ultrasound, and arteriography
  • Psychologic testing may be appropriate in some cases

Treat the underlying cause. Address atherosclerotic risk factors (weight loss and smoking cessation in all patients)

First-line treatment is with phosphodiesterase inhibitors such as sildenafil citrate (Viagra), which acts by increasing cGMP levels causing increased nitric oxide release and penile smooth muscle relaxation. It can be taken 30 to 60 minutes before anticipated intercourse. It is contraindicated with use of nitrates because together they can cause profound hypotension.

Phosphodiesterase 5 inhibitors:

  • Sildenafil (Viagra) take on empty stomach - take one hour before intercourse - can be effective 6 or 8 hours
  • Tadalafil (Cialis) - may take two hours to work and can be effective for 24 to 36 hours
  • Vardenafil (Levitra) - can be taken with food (avoid fatty foods) - take one hour before intercourse - can be effective 6 or 8 hours

May cause PRIAPISM – remember the commercials = erection longer than 4 hours. Treat with ice and stair walking, may use Sudafed

  • Intracavernosal injections of vasoactive agents (patient learns to self-administer)
  • Vacuum constriction devices are rings placed around the base of the penis that enhance venous trapping of blood; they may interfere with ejaculation
  • Psychologic therapy may be indicated to reduce performance anxiety and address underlying factors that may be causing or contributing to erectile dysfunction
  • Hormonal replacement (e.g., testosterone) in patients with documented hypogonadism
  • Penile implants for patients who have not responded to the above

Question 1
A 63 year-old man comes to the office to discuss treatment for erectile dysfunction. He is interested in learning more about the medication sildenafil (Viagra). He has a history of coronary artery disease, asthma and benign prostatic hyperplasia. Which of the following medications is contraindicated (category X) with Viagra due to the potential drug interaction?
A
Enalapril (Vasotec)
Hint:
The additive effect of sildenafil on enalapril can potentiate the anti-hypertensive effect. This is a category C interaction; monitor therapy as dosage adjustments may be required.
B
Albuterol
Hint:
There is no interaction between albuterol and sildenafil.
C
Finasteride (Proscar)
Hint:
There is no interaction between finasteride and sildenafil.
D
Nitroglycerin
Question 1 Explanation: 
The additive effect of sildenafil on nitrates can amplify cardiac preload reduction and hypotension. Sildenafil is contraindicated in patients taking nitrates.
Question 2
Which of the following is the most common cause of ED in men older than 50 years?
A
Trauma
B
Endocrine disorders
C
Vascular diseases
D
Respiratory diseases
Question 2 Explanation: 
Vascular diseases account for nearly 50% of all cases of ED in men older than 50 years. These diseases include atherosclerosis, peripheral vascular disease, myocardial infarction, and arterial hypertension. Vascular damage may result from radiation therapy to the pelvis and prostate in the treatment of prostate cancer. Both the blood vessels and the nerves to the penis may be affected. Radiation damage to the crura of the penis, which are highly susceptible to radiation damage, can induce ED.
Question 3
Which of the following forms of ED is least likely?
A
Cardiovascular-related ED
B
Smoking-related ED
C
Medication-induced ED
D
Pure psychogenic ED
Question 3 Explanation: 
Pure psychogenic impotence is relatively uncommon. It is characterized objectively by the presence of good nocturnal and morning erections and negative findings on all other tests. However, a psychogenic component is often present in men with organic ED. A history of highly variable erections that can be totally absent one day but virtually normal the next suggests a psychogenic cause. Virtually 100% of men with severe depression have ED.
Question 4
Which of the following tests is most helpful in the diagnosis of vasculogenic ED?
A
Prostate-specific antigen (PSA) screening
B
Lipid profile
C
Hormonal blood testing
D
Direct injection of prostaglandin E1 (PGE1)
Question 4 Explanation: 
A test used to evaluate penile function is the direct injection of prostaglandin E1 (PGE1; alprostadil [Caverject®]) into one of the corpora cavernosa. If the penile vasculature is normal or at least adequate, an erection should develop within several minutes. The patient and the clinician can judge the quality of the erection. If successful, this test also establishes penile injections as a possible therapy.
Question 5
Which of the following treatments is most commonly used to treat ED?
A
Androgen
B
Phosphodiesterase-5 (PDE5) inhibitors
C
Vascular endothelial growth factor (VEGF)
D
Dopamine receptor antagonists
Question 5 Explanation: 
In current practice, PDE5 inhibitors are the most commonly used treatment for ED. This drug class consists of sildenafil [Viagra®], vardenafil [Levitra®], tadalafil [Cialis®], and avanafil [Stendra®]. Sildenafil was the first in this series of PDE inhibitors.
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