eswl
TRANSCRIPT
Extra-corporeal shock wave lithotripsy in chronic pancreatitis
Shankar Zanwar
Pancreatic stones and effects Pancreatic duct stones are found in approximately 22-60% of patients
with CP. Drake DH, SurgeryLarge stones
Obstruction of the PD
Increased intraductal
pressure
Tissue ischemia and hypertension
Pain
Principle of ESWL
ESWL works by producing shockwaves from external source focused on a target in the body.
Shock waves focused on stone, build in strength that cause fragmentation.
ESWL was introduced in 1980s treatment of renal calculi and subsequently used for pancreatic and biliary calculus treatment
Lithotripter's
Three methods of shock wave generation(SW) Spark discharge – Dornier system Piezoelectric elements – Wolf system Electromagnetic deflection of the metal membrane – Siemens system
SW generation occurs in degased water
SW focused by reflection of primary wave using hemispherical disc or an acoustic lens
SW delivery in the body using water cushion or water basin
Patient selection
Indication - in patients with all of the following Recurrent attacks of pancreatic pain Moderate to marked changes in the pancreatic ductal system Obstructing ductal stones
Almost all amenable to lithotripsy – since 95% are composed of calcium carbonate on a protein matrix
Contraindication Coagulation disorders Pregnant women Patients with pacemakers Calcified aneurysms Lung tissue in the path of SW
Methods – Localization
Left and right oblique plain X-rays MRCP (+/- secretin injection) If not available – CT abdomen Intra-procedural imaging US or fluoroscopy
Monitoring was successful in only 14 % of US localization – insufficiently precise Schneider – Am J GE 1994
US better mode of localization if PD dilated
Sedation and antibiotics
Conscious sedation Epidural anesthesia General anesthesia GA more useful when ERCP planned in same session.
Antibiotics recommended if ERCP concomitant
AIG protocol Large calculi in PD >5mm Aim to break to size less than 3mm Avoided
in patients with extensive calculi all over the pancreas Head mass Multiple strictures Pancreatic ascites Isolated calculi in tail area
Application of shock waves
Position : Such that stone is not overlying the spine - right or left lateral decubitus
SWs focused on the most distally located stones first
A total of 3000-5000 SWs are delivered in one session, typical session lasting 45-60mintues
Energy levels used highest upto –0.54mJ/mm2
When concurrent ERCP planned energy level – 0.33 – 0.37mJ/mm2 - avoids duodenal edema.
A caution should be exercised in patient with ventricular extra-systole patients, SWs should delivered only in the refractory period to avoid possible ventricular arrhythmia
Repeat session may be needed if large or multiple stones.
Reported number of session required vary in different studies, mean 5 (range 1-29)
Role of additional ERCP
Various series have reported differently
Japanese series – 24/32(75%) spontaneous stone clearance after 1 or 2 sessions of ESWL alone
Ohara Am J GE 1996
High success rate here was skewed due to selection of patient without severe MPD stricture and good exocrine function
Thus ESWL can be tried alone when there is no associated stricture in the MPD.
In RCT by Costamagna et al, ESWL with ESWL and ERCP combined Pain relief similar in both arms, Rx cost increased 3X
Gut April 2007
Many series have advocated use of sphincterotomy antecedent to ESWL and endoscopic clearance of stones.
But none in RCTs
In series of 48 patients Soehendra et al showed 45% patient had complete pain relief from symptoms when two procedures were combined
This series selected patients with stricture in PDAm J GE 2000
If at all ERCP is planned stone extraction - mini Dormia basket
A 6 Fr naso-pancreatic catheter is left in place for 1-2 days and perfused with NS – 1 liter over 24 hour to eliminate stone fragments
If strictures encountered stents can be placed across in the same sitting.
Efficacy of ESWL
ESWL permits better stone clearance than traditional endoscopic procedures
Multicenter study with 555 patient under going ESWL showed Fragmentation in – 92% Stone clearance (+/- ERCP) – 72% Symptom relief - 91% Recurrence(mean follow-up of 44 month) – 22%
Miyagawa, Pancreas 2005
Technical success
Disintegration considered successful when on plain X-ray Decrease density of stone Increase stone surface area Powdery appearance of stone
These accompanied by successful deep cannulation of MPD
Using these definition success rate of fragmentation is 74-100% (across several series)
But in most reports number and size of stone did not correlate with the success of fragmentation.
GI endoscopy Schneider 2002
Decompression of PD is obtained in 70-96% of patients with ESWL followed by endoscopic drainage
Disappearance of communicating cyst and pseudocysts is seen in 74% of these cases
J of GE and Hep, N Reddy 2006
Clinical results Pain relief
Radiologic success correlates with clinical improvement
Immediate pain relief or improvement was a/w successful decompression of PD.
However complete stone clearance is not required for symptom relief
A considerable increase in wt. gain - decrease in post prandial attacks, improved pancreatic function
Pain relapse factors
Alcohol and smoking increased chances of relapse
High frequency of pain attacks before treatment (>2 attacks/month)
Longer duration of illness
Nonpapillary stenosis of PD
Exocrine and endocrine functions
Early ductal decompression may prevent further fibrosis and thus pancreatic insufficiency.
Long term studies have shown endoscopic ductal drainage can delay development of exocrine insufficiency by about 10 years
By contrast onset of DM can not changed by interventions.
Stone recurrence
Recurrence of pain in most studies was related to recurrence of stones, progressive stricturing of MPD or PD stent obstruction or migration.
In a representative series, stone recurrence developed in 22% with mean time to recurrence – 25 months.
Presence of ductal strictures increased chance of recurrence.Miyagawa, Pancreas 2005
In long term follow up study 1/3rd had relapses over a mean follow – up period of 77 months.
Significantly more when incomplete clearance after initial therapy – HR of 3.7 MPD stricture – HR of 3.4
Clinical GE and Hep, Nakamura 2005
Need for surgery
Pancreatic surgery is required in 1.4-20% of patients Technical failure of stone disintegration Failure of endoscopic ductal drainage Complications of pancreatitis beyond the capability of endoscopic
management. As definitive treatment for biliary drainage (H-J) or pancreatic drainage(P-J)
Complications of ESWL
Noted complications of ESWL Common and mild
Petechiae around area of penetration of SWs Erosions in the gastric antrum at times hemorrhagic
Perirenal hematoma Biliary obstruction Bowel perforation Splenic rupture Lung trauma Necrotising pancreatitis
Summary
ESWL can be 1st line Rx for painful CCP – a/w obstructive ductal calculi leading upstream dilatation – Grade 2B
Best fragmentation rates are obtained when fluoroscopic targeting system used to focus stones
Summary
As general rule endotherapy should be used after ESWL for drainage of calculi in case of strictures in PD – but case based discretion needed
Definitive pain relief can be expected for long term in 2/3 of patients
Best results obtained in non smokers and when ESWL offered early in the course of disease.
Thank you