clavien_atlas_of_upper_gastrointestinal_and_hepato-pancreato-biliary_surgery2007-10-01_3540200045_springer
.pdf
404 |
SECTION 3 |
Liver |
|
|
|
|
Procedure |
|
|
|
|
STEP 1 |
Evaluation of the tumor |
|
|
In order to exclude extrahepatic disease, the procedure is started with a diagnostic |
|
|
|
|
|
laparoscopy or a mini-laparotomy. The liver is examined bimanually and the tumors are |
|
|
investigated by ultrasound with respect to number, size and distance of bile ducts and |
|
|
vascular structures. Next, the lesser sac is opened and suspicious lymph nodes are sent |
|
|
for histological examination. Heated bed blankets should be used to prevent |
|
|
hypothermia. |
|
|
|
|
STEP 2 |
Insertion of the probe and applying cryotherapy |
|
|
Access to the liver is gained by a bilateral subcostal or triradiate incision. For safety |
|
|
|
|
reasons, the probes need to be checked for leaks under water with liquid N2 running. Using ultrasound guidance (A-1), the probes (3–10mm in diameter) can be inserted at the center of the tumor (A-2).
A-1
A-2
Cryosurgery |
405 |
|
|
STEP 2 (continued) |
Insertion of the probe and applying cryotherapy |
|
For larger tumors multiple probes in a predetermined relationship are used (B). |
|
|
|
Cryosurgery can also be combined with a partial hepatectomy. In such cases an edge |
|
probe is used to destroy the remnant tumor at the resection surface. This probe does not |
|
need to be inserted into the liver (C). |
|
The iceball made by cryoablation should extend ≥1cm beyond the tumor margin. |
|
This should be demonstrated with ultrasound guidance. Since it is not possible to see |
|
through the ice, the posterior margin is visualized by ultrasound from behind the liver. |
|
After demonstration of a 1-cm margin, we thaw passively and wait for 1cm to thaw |
|
out and then refreeze. Twin freeze-thaw cryotherapy lowers local recurrence rate. |
|
A single cryoablation cycle takes approximately 7–10min, depending on the size |
|
of the lesion. |
B
C
406 |
SECTION 3 |
Liver |
|
|
|
STEP 3 |
Removing the probes |
|
|
Before the probe can be taken out, it has to be rewarmed with warmed nitrogen gas. |
|
|
|
|
|
Then, the probe can gently be pulled out of the liver, and the tract can be filled with |
|
|
surgical or alternate hemostatic foams. |
|
|
|
|
STEP 4 |
Cracks |
|
|
The changes in temperature can cause fractures in the liver which can cause bleeding. |
|
|
||
|
These “cracks” need to be managed by liver sutures and packs. |
|
Cryosurgery |
407 |
|
|
Postoperative Tests
Prediction of Cryoshock
■Full blood count (FBC), looking for thrombocytopenia particularly on day 3
■Liver function test (LFT), especially aspartate aminotransferase (AST), highest rise day 1
■Kidney function tests
Postoperative Complications
Cryoshock
Cryoshock is a syndrome of multiorgan failure including renal impairment, pulmonary edema, coagulopathy, and disseminated intravascular coagulation. The incidence of cryoshock is around 1% and is only seen with large volume distraction and especially with the complete twin freeze-thaw technique.
Hepatic Abscess
Very rare, except with synchronous bowel resection and cryoablation.
Pleural Effusion
Common, especially during right-sided hepatic ablation.
Biloma or Biliary Leak
Biliary Strictures
Biliary strictures can occur but are very rare within the liver. The main risk is for large lesions in segment IV lying at the bifurcation of the PVS.
408 |
SECTION 3 |
Liver |
|
|
|
|
Tricks of the Senior Surgeon |
|
■Do not wash the lesion or the abdominal cavity with warm saline to speed thawing, as this can result in dramatic cracking.
■Make sure there is liquid N2 in the machine before you start the procedure.
■Use multiple probes for multiple lesions simultaneously to increase the speed of procedure. However, single lesions are better treated by one large probe than several small probes due to the risk of cracking between small probes.
■Large lesions need more than one probe.
■Before closing the abdomen, make sure the iceball has thawed completely and there is no bleeding from any cracks.
■Aim for a high urine output (intraand postoperatively) to prevent kidney failure.
Radiofrequency Ablation of Liver Tumors
Michael M. Awad, Michael A. Choti
Indications and Contraindications
Indications |
■ |
Unresectable malignant tumors of the liver (e.g., hepatocellular carcinoma, colorectal |
|
|
|
metastases, neuroendocrine tumors, selected other types of metastases) |
|
|
■ |
Tumors <5cm in size (most effective for lesions <3cm) |
|
|
■ |
Palliative treatment of symptomatic tumors (e.g., neuroendocrine metastases) |
|
|
■ |
Bridge to liver transplantation (hepatocellular carcinoma) |
|
|
■ |
Access: |
|
|
|
– |
Open: |
|
|
|
– In combination with resection |
|
|
|
– When resection is planned, but unresectability is found at time of laparotomy |
|
|
|
– In difficult locations or selected cases when multiple ablations are required |
|
|
|
– percutaneus: not discussed in this atlas |
|
|
– |
Laparoscopic: |
|
|
|
– Patient fulfills basic requirements to undergo surgery |
|
|
|
– Lesion(s) amenable to laparoscopic approach |
|
|
|
– percutaneus: not discussed in this atlas |
|
|
Extrahepatic disease (unless extrahepatic sites are resectable or when there is |
|
Contraindications |
■ |
||
|
|
palliative indication) |
|
|
■ |
Perihilar tumor location |
|
|
■ |
Significant coagulopathy or thrombocytopenia |
|
|
■ |
Ascites |
|
|
■ |
Previous bilio-enteric anastomosis (relative contraindication due to the increased |
|
|
|
risk of hepatic abscess following radiofrequency ablation, RFA) |
|
Preoperative Investigation and Preparation for the Procedure
CT or MRI: |
Assessment to rule out resectability and determine if lesions are |
|
ablatable |
PET: |
Evaluation for presence of extrahepatic disease (e.g., colorectal |
|
metastases) |
In operating |
Grounding pads (varies depending on RFA manufacturer) |
room: |
– Place greater than 50cm from electrode |
|
– Orient pads with long axis perpendicular to body axis |
|
– Use multiple pads when indicated |
410 |
SECTION 3 |
Liver |
|
|
|
|
Guidance Imaging Modality |
|
Imaging is used for lesion localization, probe guidance, and ablation monitoring.
The following features of each imaging modality must be considered.
■Ultrasound
–Most common method used
–Inexpensive and real time feedback
–Sometimes difficult to visualize lesion adequately
–Increased echogenicity from microbubbles
–Microbubbles are not a true representation of zone of coagulation necrosis
–Echogenicity may obscure further needle positioning
■Alternatives: CT or MRI
–Transaxial needle track required
–CT fluoroscopy is a useful adjunct
–For MRI, a compatible RFA needle is required
Probe Selection
A number of different probes are commercially available for performing RFA (A-1, A-2, A3). Probes are typically 14–17.5gauge, 15–25cm long, insulated cannulas containing one to three straight needle electrodes (ValleyLab) or five to ten individual hook-shaped electrode arms or tines (RITA Medical, Boston Scientific). Some of the newer probes have a cooled-tip system utilizing circulating saline (ValleyLab, Berchtold), or local saline infusion (RTA Medical).
A-1 |
|
A-2 |
|
A-3 |
Radiofrequency Ablation of Liver Tumors |
411 |
|
|
Procedures
|
Open Technique |
|
|
STEP 1 |
Access and assessment of tumors |
|
Incision, evaluation, palpation and mobilization of the liver are performed as for a liver |
|
|
|
resection. The abdomen is explored for the presence of extrahepatic disease and the |
|
evaluation is completed by intraoperative ultrasound (IOUS) to identify/confirm the |
|
location and the size of the lesions (A). The feasibility of the ablation is determined and |
|
the number of needed ablations is calculated. |
|
|
STEP 2 |
Placement of the probe and ablation of tumors |
|
The probe is aligned so that its trajectory lies in the plane of the ultrasound image and |
|
|
|
does not intersect vital structures such as blood vessels and bile ducts. It is advanced |
|
under image guidance until the tip is either close to the proximal edge of the tumor |
|
or near the distal edge, depending on the probe type (B-1). The deployed probe is |
|
visualized in perpendicular view to confirm adequate tip position and deployment (A). |
|
The probe tines are deployed and radiofrequency energy is applied according to the |
|
manufacturer’s directions (B-2, B-3). |
412 |
SECTION 3 |
Liver |
|
|
|
STEP 3 |
Ablation of large or irregularly shaped lesions and tract ablation |
|
|
|
|
For large or irregularly shaped lesions, multiple ablations may be needed (Step 2 is repeated as necessary). A pattern of overlapping spheres or cylinders is used to cover the lesion while maintaining adequate margins.
With some devices, tract ablation is performed to cauterize the tract and to minimize seeding. The probe is withdrawn 1cm at a time in tract ablation mode on the radiofrequency generator, allowing temperature to reach >70°C at each step. This is continued until the probe is completely removed.
Radiofrequency Ablation of Liver Tumors |
413 |
|
|
|
|
|
Laparoscopic Approach |
|
|
|
|
STEP 1 |
Positioning of the patient and access |
|
|
Depending on the location of the tumor(s), the patient is placed in the supine or left |
|
|
|
|
lateral decubitus position. A minimum of two laparoscopic trocars are placed: a 12-mm periumbilical camera port and a 12-mm laparoscopic ultrasound port in the right flank. The radiofrequency probe can be placed percutaneously, through a sheath, or through a 5-mm right subcostal port. More ports may be required if additional procedures are to be performed (e.g., liver mobilization, partial resection) (A-1).
A-1