Chapter 191 - Erectile dysfunction Flashcards
Prevalence of erectile dysfunction
50% of men > 40
Erectile dysfunction definition
recurrent or consistent inability to maintain penile erection for satisfactory sexual performance
Anatomy of the penis
1) paired dorsal corpora cavernosa - supported by tunica albuginea
2) ventral corpus spongiosum (urethra)
Blood flow to penis
internal pudendal artery –> common penile artery –>
1) dorsal
2) cavernosal
3) bulbourethral
Accessory pudendal artery origin
1) EIA
2) obturator
3) vesicle
4) femoral
Cavernosal arteries terminate at what
helicine arteries
provide tumescence of penis
Venous drainage of the penis
DEEP VEIN
Lacunar space –> subtunical venules –> emissary veins –>
1) cavernosal veins
2) deep dorsal vein
3) spongiosal veins
–> prostatic venous plexus or internal pudendal veins
SUPERFICIAL VEIN
Superficial dorsal vein –> saphenous vein
Innervation of the penis
1) somatic nerve
2) parasympathetic nerve
3) sympathetic nerve
Somatic nerve function for the penis
1) sensory
2) contraction of bulbocavernosus and ischiocavernosus muscle
Parasympathetic nerve for penis origin
S2-S4 - hypogastric plexus
Sympathetic nerve for penis origin
T12-L2 - pelvic plexus
Autonomic nerves coalesce into this nerve before entering penis
Cavernous nerve
Pathway of the cavernous nerve into penis
Posterolateral aspect of prostate –> urogenital diaphragm along with urethra
Innervation of the cavernous nerve
Helicine arteries
Trabecular smooth muscle
Physiology of erection
1) sexual stimulation
2) increase parasympathetic activity
3) cavenous nerve stimulation
4) penile smooth muscle relaxation (NO pathway)
5) increase bloodflow through penile arteries
6) sinusoid expansion
7) compressiong of subtunical venules (veno-occlusive mechanism)
8) increase intracavernous pressure
Cellular mechanism of nitric oxide in erection
NO –> cAMP and cGMP –> decrease Ca2+ intracellular –> smooth muscle relaxation
Causes of erectile dysfunction
1) psychogenic (10-15%)
2) neurogenic (uncomon)
3) endocrinologic
4) vasculogenic
5) drug-induced
Psychogenic ED feature
1) good nocturnal erection
2) sudden-onset ED with intermittency
Neurogenic ED subclassification
1) supraspinal
2) spinal
3) peripheral
Supraspinal ED causes
1) tumor
2) stroke
3) Parkinson
4) dementia
5) temporal lobe epilepsy
Spinal ED causes
1) MS
2) spinal cord injury
3) transverse myelitis
4) myelodysplasia
5) lumbar disc disease/surgery
Peripheral neurogenic ED causes
1) lower motor neuron lesion
2) trauma
3) pelvic pathology
4) pelvic surgery (radical prostatectomy)
Endocrine ED causes
1) androgen ? no clear link
2) hyperprolactinemia –> inhibit LH –> low libido
3) hypothyroidism –> low LH
4) hyperthyroidism –> high estradiol
Vasculogenic ED risk factors
1) CAD
2) DM
3) HTN
Vasculogenic ED theoretical mechanisms
1) flow-limiting stenosis
2) lower oxygen tension (low PGE1, high E2, high TGF beta1 (collagenization of cavenous smooth muscle)
3) endothelial dysfunction lack of NO
4) Corporal veno-occlusive dysfunction
Rate of abnormal ECHO in patients with vasculogenic ED
20%
5 year risk of cardiovascular events in patients with ED
45%
Peyronie disease in ED
scar tissue resulting in deranged drainage of the cavernous tissue
Drugs associated with ED
1) thiazide
2) non-selective beta blocker
3) ARB
4) SSRI
5) antiandrogen (prostate cancer use)
6) 5-alpha reductase inhibitor (finasterid, dutasteride)
7) digoxin
Penile brachial index
Cuff at base of flaccid penis
no evidence
not used
Intracavernosal injection testing
Vasodilatory meds (PGE1, papaverine, phentolamine) injected test for erection and detumesce
if no relaxation after 1 hour then phenylephrine given
no evidence largely unused
Duplex ultrasound of the penis how its done
vasodilator use
erection obtained then measure velocities
transducer frequency 7.5 - 12 MHz
Duplex of penis cutoffs
PSV < 25 cm/s = arteriogenic ED
sen 100
spe 86
> 10 cm/s difference between sides = atherosclerotic lesion
EDV > 5cm/s = CVOD
RI < 0.75 = abnormal
Dynamic infusion cavernosometry and cavernosography indications
1) young men with trauma for revascularization
2) young men failed pharmacotherapy to rule out CVOD
3) primary ED to rule out CVOD
4) medicolegal case
5) Peyronie disease with ED to rule out CVOD
DICC steps
CAVERNOSOMETRY
1) butterfly needle in each corporal body - one to pressure transducer, one to heparin
2) inject vasoactive drugs
3) record 4 things:
1) equilibrium pressure in corpus cavernosum
- assessment of intracavernosal pressure 10-15 min after vasoactive agent
2) cavernosal artery inflow gradient for both sides
- difference between brachial artery SBP and cavernosal artery occlusion pressure
3) flow to maintain a given intracavernosal pressure
4) pressure decay in mmHg/30s = pressure drop after raising intracavernosal pressure to 150 mmHg
CAVERNOSOGRAPHY
1) radioopaque non-ionic dye into intracavernosally
2) rule out CVOD
DICC normal values
1) cavernosal artery occlusion pressure < 30 mmHg
2) flow to maintain ICP < 5 ml/min
3) pressure decay < 45 mmHg/30 seconds
DICC result interpretation
Plot flow to maintain against ICP
1) curvilinear pattern = CVOD
2) parabolic pattern = excessive sympathetic tone
Selective internal pudendal angiography indication
1) arterial insufficiency without CVOD
2) focal occlusion in one or both common penile or cavernosal arteries
3) perforating branches traveling from dorsal to cavernosal artery
4) at least one patent inferior epigastric artery as donor artery
5) at least one patent dorsal artery as recipient artery
6) patient with high flow priapism
Treatment of ED algorithm
1) lifestyle
2) PDE5 inhibitor + psychosocial
3) intracavernosal injection, intraurethral suppository, vacuum constriction device
4) penile implant surgery, vascular surgery
PDE5 inhibitor types, Tmax and half life
Sildenafil (1998) Viagra
- Tmax 60 min; half life 4 hours
vardenafil (Levitra)
- Tmax 42 min; half life 4.5 hours
tadalafil (Cialis)
- Tmax 120 min; half life 17.5 hours
Avanafil (Standra)
- Tmax 45 min; half life 5.1 hours
PDE5 inhibitor mechanism of action
PDE5 normally degrades cGMP
Prolonged cGMP –> decrease intracellular calcium –> smooth muscle relaxation
Side effects of PDE5 inhibitors
1) headache
2) flushing
3) nasal congestion
4) heartburn
5) altered color vision
6) n/v
7) cardiovascular
8) diarrhea
9) dizziness
10) myalgia
Contraindication of PDE5 inhibitors
1) nitrate use
2) antiarrhythmic (Type 1A or 3) for vardenafil only = long QT
Intracavernosal injection therapy types
1) PGE1 (alprostadil/Caverject)
2) phentolamine
3) papaverine
Trimix has all 3
Bimix doesn’t have PGE1
Mechanism of PGE1
Activate prostaglandin receptor –> increase cAMP
Mechanism of phentolamine
non-selective alpha antagonist –> relax SMC
Mechanism of papaverine
nonspecific PDE inhibitor –> increase cAMP and cGMP –> erection
Response time of ICI
5-10 minutes
Success rate of PDE5
69%
Success rate of ICI
89%
Complication of ICI
Priapism 0.25 - 7.3%
Reversal of prolonged erection
Alpha-adrenergic agonist Phenylephrine - intracavernosal administration
Intraurethral PGE1 suppository steps, success and complication
1) small plastic device into urethral meatus
2) pellet deposited into urethra
variable efficacy
33% get pain
5% get bleeding
Maximum time of vacuum constriction device with compression ring
30 min
Implantable penile devices
1) malleable
2) hydrualic (two piece or three piece)
Satisfaction after penile implant
75-97%
Infection after penile implant
0.7-3%
Surgical revascularization in ED
Inferior epigastric artery to dorsal artery bypass
Success after surgical revascularization in ED
55%
Key selection for surgical revascularization in ED
young < 40 focal lesion otherwise healthy no other underlying disease no CVOD
Complication after surgical revascularization in ED
1) failure to improve
2) inguinal hernia
3) penile shortening
4) loss of penile sensation
5) glans hyperemia if dorsal vein used
Venous ligation in crural enous leaks success rate
82-93%
Rate of ED preop in AAA and AIOD
22-39% historically
higher in contemporary data with better definition
Aneurysm detection and management ADAM study on ED
1136 patients with 4-5.4 cm AAA
surveillance vs immediate open repair
Impotence higher in immediate repair 18months to 4 years
higher ED over time also noted = progression of disease
