Liver resection is still a surgical challenge, due to the high risk of hemorrhage during the transection and the complicated biliary and vascular anatomy of the organ.
The history of the development of surgical techniques for liver resection had it’s main goal, the fight against bleeding. Before 1980’s, liver resection was associated to 10-20% mortality rates.
Currently the in hospital mortality nears 5% in specialized centers. Even though there is a better patient selection, the reduction in blood loss and perioperative transfusions have contributed to the better patient survival. Massive bleeding and transusions not only rise the morbi-mortality risk, but also compromise long term survival after resection of liver tumors, due to the associated immunesuppression, which leads to recurrence.
Finger fracture of the liver parenchyma has been the classic technique for liver resection. During the last 20 years, technological advances have lead to the development of specific instruments such as the compact ultrasonic surgical aspirator, water jet, harmonic scalpel, Ligasure®, and TissuLink®. Another thing that has reduced intraoperative blood loss is the better delineation of the transection plane with the use of IOUS.
Delineation of the Proper Transection Plane
This is not only important to achieve an adequate margin for resection of liver tumors, but also to avoid inadvertent injuries to major hepatic vessels or ducts.
This delineation starts with an adequate knowledge of the computed tomography, to define the different relationships of the tumor and the hepatic veins and biliary pedicles. This can be evaluated transoperatively by IOUS.
Without this knowledge inadvertend injuries may occur during transection, which can lead to massive bleeding or biliary injuries. In some occasions tumor exposition during transection can happen. Generally a 1cm margin is required, but this is still controversial for HCC (Ann Surg 2000; 231: 544-551).
IOUS allows localization of the portal pedicle of each liver segment. Some surgeons perform the liver tattoing with blue dye, injected directly to one portal branch to delineate the segment that is going to be resected.
Techniques of Liver Transection
Finger fracture/clamp crushing
Vacular control is very important to hepatobiliary surgeons. Transection is particularly difficult in cirrhotic livers due to fibrosis. The risk of bleeding is also high in this pathology.
Finger fracture involves crushing the liver parenchyma while under inflow occlusion. This technique was introduced by Lin in 1958 (J Formosa Med Assoc 1958; 57: 742-749). Subsequently was perfected by the introduction of other instruments such as the Kelly clamp (Ann Surg 1974; 180: 285-290). Currently is one of the most widely used techniques today.
Ultrasonic Dissection
In a lot of centers, the use of Cavitron® CUSA (Compact Ultrasonic Surgical Aspirator) has been the standard for liver resection. With this technology, liver parenchyma is fragmented by means of ultrasonic energy and aspirated exposing the vascular and ductal structures, which can be clipped or ligated.
This technique has demonstrated reduction in blood loss, morbidity, when compared with finger crushing. The surgical margin is also wider with this technique (Br J Surg 1996; 83: 117-120).
Water Jet
The water propulsion dissector uses a water jet instead of ultrasonic energy to fragment liver parenchyma and expose vascular and biliary structures. This technique is not as popular as CUSA. Currently only one study showed the results with this technique (Zentralbl Chir 2001; 126: 586-590).
Harmonic Scalpel
More recently, newer technologies have allowed sealing of lesser vessels during liver transection. This technique can be used alone or in conjuction with others, such as finger crushing or CUSA.
It uses ultrasonicaly activated shears to seal small vessels that stand between the vibrating blades. The blades vibrate at 55.5 kHz and can easily dissect parenchyma. The coagulative effect is caused by protein denaturalization that occurs due to destruction of hydrogen bonds and heat generation. The tissue cutting effect derives from a saw mechanism.
It has been used in laparoscopic and open procedures, without reported biliary leaks in Schmidbaier’s study in 2002 (Ann Surg 2002; 235: 27-30).
One disadvantage of this technique is it’s capacity to dissect the liver parenchyma around the hepatic veins, because of its difficulty in controlin large vessels. Even though, it is widely used in laparoscopy.
Ligasure
Another instrumet designed for sealing small vessels using a different principle. Combining compression and bipolar radiofrequency energy, a change in the vessel wall’s collagen and elastin, sealing of vessels as large as 7 mm can be achieved.
Doubts concernig its capacity of sealing large bile ducts persist, and ths was reafirmed in a recent study (World J Surg 2005; 29: 110-112). It is useful for laparoscopic procedures.
TissueLink
A new technology using saline-linked radiofrequency energy has been developed. The saline runs towards the tip of the instrument to link the radiofrequency energy with liver surface, achieving coagulation.
This instrument has a tip that allows transection and vessel sealing simultaneously. Can be used during laparoscopic surgery. You can watch a video here.
Radiofrequency Assisted Liver Transection
Radiofrequency ablation is a good technoque for the treatment of liver tumors. With this technique, a Cool-tip® electrode is inserted in the transection plane serially every 1-2 cm, applying energy for 1-2 minutes, to create coagulated cylinders, that then can be cut by a scalpel.
The advantage of this technique is its simplicity, when compared to the other techniques. One of the potential disadvantages is the sacrifice of liver prenchyma that is coagulated, leaving up to 1 cm of necrotic tissue, which can be critical in cirrhotic patients.
There exists the concern for damage to the hilar structures and hepati veins. The use of this device has to be evaluated. You can watch a video here.
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2007/10/10
Surgical Techniques for Liver Transection
2007/10/09
A Comparative Study with the Typical Mass Forming Intrahepatic Cholangiocarcinoma
The Department of Hepatobiliary and Pancreatic Surgery, Tokyo, Japan, published in this month's issue of WJS an very interesting study comparing the mass forming cholangiocarcinoma vs the intrahepatic cholangiocarcinoma with periductal invasion.
Between January 1, 1998, and December 31, 2004, a total of 94 patients with ICC underwent macroscopic curative resection, and the macroscopic type of the tumors was assessed prospectively. Seventy four patients presented with the MF type. A multivariate analysis was conducted to identify the potential prognostic factors.
involvement, and positive surgical margin.
They concluded that identification of the macroscopic type of the tumor is useful for predicting survival after hepatectomy in patients with ICC. The MF plus PI type of ICC appears to have a more unfavorable prognosis, even after radical surgery, than the MF type of ICC.
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2007/10/08
Hepatocellular Carcinoma: Early Diagnosis
In patients with a sympromatic HCC, the overall survival doesn’t exceed several months. Multiple treatments have been proposed: Resection, liver transplantation, chemoembolization, and alcoholization. Independetly of the treatment, the efficacity of each one depends on the size of the tumor. That is the main reason why early diagnosis palys an important part in the management.
Lots of diagnostic methods have been developed for the diagnosis of HCC: Ultrasund, CT scan, MRI. Each one has it’s own problems, because none of them can diagnose the small nodules of hepatocellular carcinoma, and sometimes cannot differentiate regeneration nodules from HCC.
In the corrhotic patient, one can find a great amount of regeneration nodules. In the past, these nodules had different denominations, and that was the reason why the terminology was simplified in an international consensus (Hepatology 1995; 22: 992-993).
The dysplastic nodule is a lesion made up of hepatocytes surrounded by fibrosis with signs of dysplasia, but without crtieria of malignity. It’s size is usually inferior to 10 mm, but can reach 20 mm. One must not call them “ adenomatous hyperplasia “ or regeneration macronodule”. They must be classified as low or high grade dysplasia.
The third type of nodule is the HCC nodule. It is a nodule with cytological and hystological atypias, with crteria of malignity. There seems to be a relation between the cirrhotic nodule, the dysplastic nodule, the small HCC, and the sever HCC (Semin Liver Dis 1995; 15: 360-371; Hepatology 1992; 16: 949-955).
The smallest the nodule, more the chances of it being benign. This doesn’t exclude the possibility of HCC in small nodules. That is why size is not an absolut criteria. A criteria to differentiate between a cirrhotic nodule and HCC is the vascularization. The hepatic sinusoidal capillaries are irrigated by portal vein and branches or the hepatic artery. A benign nodule has a mixed vascularization, with a predomination of the portal flow. An HCC doesn’t have portal vascularization, but it’s irrigation depends on the arterial flow (neoangiogenesis). This is something that helps in their diagnosis (Radiology 1991; 178: 493-497).
The time for an HCC to double its size is about 112 days (Hepatogastroenterology 1993; 40: 311-315). It may occur soonr (<40 days) or much later (400 days). All these can make us understand why the difficulty of making an early diagnosis, specially in cirrhotic livers, and liver with an important amount of preserved architecture.
Imaging Studies
Ultrasound
Minimally invasive technique, with a low cost and common use. Has been used for more that 2 decades in the diagnosis of HCC. Small HCC’s are frequently hyperechogenic. But they may be hypo or isoechogenic.
Sometimes they may be surrounded by an hypoechogenic halo corresponding to the pseudocapsule, or may be heterogeneous with hypo or hyperechogenic zones inside the tumor. This characteristics are more frequently found in HCC, but are difficult to see in small nodules. Multiple studies have proposed the bi-annual follow-up with AFP dosages (J Hepatol 1994; 21: 1029-1034; J Hepatol 1994; 20: 65-71; Cancer 1996; 78: 977-985). These studies showed the success of this starategy.
CT scanning
One of the main characteristics of HCC’s is their almost exclusive arterial vascularization. After the contrast injection, during the arterial phase, hypervascular tumors can be easily viewed, when compared to the normal liver, which has mainly portal vascularization.
Hypervascular tumor apear hyperdense during the arterial phase, but in the mixed phase, they become isodense. The typical semiology of a small HCC is that of a small nodule, usually < 3 cm in diameter, visible only during the arterial phase (Radiology 1996; 199: 505-511). There are certain cases, hemochromatosis for example, when these nodules can be hypodense, but the density of the liver parenchyma is augmented.
The sensibility and specificity of this method for tumors 1-2 cm reaches 43%. But it can make the diagnosis of lesions as small as 1 cm.
Magnetic Resonance Imaging
The major interest in this method is due to its contrast potential, and the possibility of dynamic testing that can be repeated continually. The differential diagnosis between a regeneration nodule and a small HCC is difficult, specially in those cases with hyperintense nodules on T1 and not visible on T2. In these cases, a CT scan is recommended.
Follow-up of Patients with Liver Cirrhosis
To impact survival of HCC, one must fight for early diagnosis. This leads to high costs regarding patient management. This follow-up is helpful in patients with small HCC, Child A and some Child B cases, specially hemochromatosis, or patients who may undergo liver transplantation.
An augmentation of the AFP level is an indication for close follow-up. The usual follow-up consists of US and AFP levels every 6 months. We must remember that the size may double in the majority of cases in 4 months, so the follow-up can be performed every 4 months rather than every 6 months.
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2007/10/07
Thymoglobulin Induction Protects Liver Allografts From Ischemia/Reperfusion Injury
Twenty two cadaveric liver transplant recipients were randomized to receive either TG (1,5 mg/kg/dose) during the anhepatic period and QOD x 2 doses, or no TG. Maintenance immunosupression consisted of Tacrolimus (or Cyclosporine) and steroids in both groups. Donor byopsies were taken during the organ procurement, cold storage, and 1 hour after re-vascularization.
Patient survival at 3 months was 100%. There was no incidence of PNF and no need for re-transplantation. The incidence of acute rejection was similar in both groups. Patients with TG had significanly decreases in alanine amino transferase and total bilirubin.
Clin Transplant 2005: 19: 507-511
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2007/10/06
Surgical Management of Colorectal Liver Metastases
The appearance of liver metastases during the evolution of a primary colorectal tumor is a bad prognosis. To prolong the patient's life, many therapies have been proposed, more importantly, chemotherapy.
Today, surgical resection is the only therapeutic option for cure, and attains survival curves at medium and long term, superior to those obtained by other treatments. Resection achieves survival rates of 26 to 45% at 5 years, while it is almost zero in those cases not resected.
Liver resection leads to low morbidity and mortality, close to 1% in specialized centers. It must be emphasized that out of all the patients with colorectal liver metastases, only 10 to 20% can be resected. Today, the challenge is to develop new startegies thatt combine surgical resection with techniques of tumor destruction such as RFA, cryotherapy, portal embolization, and new chemotherapy protocols, with the goal of making those lesions that are initially considered unresectable, resectable.
Principles of Curative Liver Resection
The techniques are divided into 'anatomical' or 'non-anatomical' resections.
Anatomical Resections
They follow the liver segmentation principles described by Couinaud. They are considered as minor, when less than 3 segments are resected, or major, when resection inludes more than 3 segments.
Non-Anatomical Resections
They include the resection of a portion of the liver independently of the liver scisures and glissonian pedicles. They refer mainly to metastasectomies. The liver resection depends on the size of the tumor.
Rules to Respect During Hepatectomy
Independently of the type of liver resection, one must follow these rules in order to avoid postoperative complications:
* Functional liver parenchyma preservation of at least 30% of the total liver mass, to avoid hepatic insufficiency.
* Limit blood loss, in order to avoid transfusions, because it is a known risk factor that favors recurrence.
* Respect the 1 mm margin, to reduce the risk of recurrence.
* Respecto glissonian pedicles destined to the remaining segments, to avoid segmental exclusion, ischemia and necrosis, and biliary fistulas.
Preoperative Patient Evaluation
Before even thinking on performing a liver resection, it is necessary a thorough oncologic examination, seeking other localizations, and also to verify the absence of contra-indications.
Regarding morphological tests, an abdominal US, CT and afterwards a MRI, allow to acquire a better knowledge regarding number of metastases, precise location, relationship with the portal pedicle and the hepatic veins.
Pulmonary localizations must be ruled out systematically, using CT examination. If these lesions are resectable, they dont constitute a contraindication to liver resection. The same goes for all of the extrahepatic metastases.
A colonoscopy is always performed to rule out recurrence, even if the primary tumor has already been resected. If necessary, a bone scan or a brain CT can be performed.
Regarding the blood chemistry, it consists of liver function tests, tumor markers, coagulation profile and clearance of green indocyanine test, which allows to better evaluate liver function, specially in those patients who received neoafjuvant chemotherapy or those with a preexistent liver pathology (hepatitis, cirrhosis).
Valid Indications and New Operative Strategies
A patient with liver metastases limited to one segment without extrahepatic dissemination is always a candidate for liver resection. The challenge for hepatobiliary surgeons is to achieve the necessary resources and strategies that allow the patients' benefit.
The liver surgical progress and the development of new surgical techniques, like RFA, cryotherapy, new radiological interventions such as portal embolization, and new chemotherapy drugs have permitted the elaboration of this new strategies, which make possible curative resections to patients initially considered unresectable. Patients can be divided into four groups:
1. Patients with a voluminous hepatic metastases in which resection leaves an insufficient amount of functional liver parenchyma.
2. Patients with bilobar metastases.
3. Patients with recurrence after resection.
4. Patients with a primary colorectal tumor and synchronous liver metastases.
Patients with a Voluminous Liver Metastases
Two alternative may be offered: Tumor downsizing with systemic or local chemotherapy, and hypertrophy of the future remaining liver (non-tumoral) by portal embolization.
* Downsizing: Bismuth et al, from the Paul Brousse Hospital in France, showed in a study with 53 patients presenting with liver metastases initially non-resectable, that the use of neoadjuvant chemotherapy with 5-fluorouracyl, folinic acid and oxalyplatin, achieved an adequate tumoral downsizing, with similar results as those patients initially resectable. (Ann Surg 1996; 224: 509-522).
* Portal Embolization: When resection is not viable due to insufficient functional liver parenchyma (usually left lobe), surgeons look for hypertrophy of the non-tumoral liver. Once embolization is performed, hypertrophy is evaluated 5-6 weeks after the procedure. If the future remaining liver is >30%, then hepatectomy can be performed.
Patients with Bilobar Metastases
Many therapeutic options have been described:
* Two-stage Hepatectomy including Portal Embolization: The success seen for one stage hepatectomies after portal embolization, lead surgeons to the two stage procedure. This strategy consists on a first stage of metastases resection in the future remnant, and embolization of the tumoral liver. On a second stage, a right hepatectomy is performed, which can be extended to segment 4, after an adequate hypertrophy is achieved.
* Two-stage Hepatectomy: Described by René Adam, consists on the resction of the majority of the metastases in a first stage. Then resection of the remaining lesions after acquiring liver regeneration. In between, patients receive chemotherapy.
* Hepatectomy associated to resection and tumoral destruction by local treatment: Here, the greater lesions are resected and the lesser ones are destroyed locally by either RFA or cryotherapy.
* Two-stage Hepatectomy after neoadjuvant chemotherapy: The goal is to achieve an adequate downsizing of the tumor that allows for a resection in a one-stage or two-stage procedure.
Patients with Recurrence after Resection
Surgery is the only curative option for these patients. It has been shown that patients with a liver recurrence isolated or associated with a resectable extrahepatic metastases, resection of all the tumoral tissue achieves an overall survival similar to patients without recurrence.
Resection of the recurrence turns the clock back to zero. In these cases, tumor destruction by RFA or cryotherapy extends the indications.
Patients with a Primary Colorectal Tumor and Synchronous Metastases
Surgical startegies remain controversial. Those who favor simultaneous resection, and those who oppose it, differ in terms of oncological basis, immunological techniques and patient comfort. Jaeck showed that there was no difference between the two approaches (Chirurgie 1999; 124: 258-263).
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