Clinicopathologic effects of cryotherapy on hepatic vessels and bile ducts in a porcine model

Endoscopic cryotherapy: Indications, techniques, and outcomes involving the gastrointestinal tract

Endoscopic cryotherapy is a technique utilized for the ablation of target tissue within the gastrointestinal tract. A cryotherapy system utilizes the endoscopic application of cryogen such as liquid nitrogen, carbon dioxide or liquid nitrous oxide. This leads to disruption of cell membranes, apoptosis, and thrombosis of local blood vessels within the target tissue. Several trials utilizing cryotherapy for Barrett's esophagus (BE) with variable dysplasia, gastric antral vascular ectasia (GAVE), esophageal carcinoma, radiation proctitis, and metastatic esophageal carcinomas have shown safety and efficacy. More recently, liquid nitrogen cryotherapy (cryodilation) was shown to be safe and effective for the treatment of a benign esophageal stricture which was refractory to dilations, steroid injections, and stenting. Moreover, liquid nitrogen cryotherapy is associated with less post procedure pain as compared to radiofrequency ablation in BE with comparable ablation rates. In patients with GAVE, cryotherapy was found to be less tedious as compared to argon plasma coagulation. Adverse events from cryotherapy most commonly include chest pain, esophageal strictures, and bleeding. Gastric perforations did occur as well, but less often. In summary, endoscopic cryotherapy is a promising and growing field, which was first demonstrated in BE, but the use now spans for several other disease processes. Larger randomized controlled trials are needed before its role can be established for these different diseases.

Cryosurgery: early ultrastructural changes in liver tissue in vivo

BACKGROUND

Experimental observations with regard to freezing in vitro cell lines and fluid systems led to the application of low temperatures to in vivo biological systems. For the first time, this report describes the cryosurgical response of liver parenchyma and the early ultrastructural cellular changes in liver tissue, i.e., cryosurgery, in vivo.

MATERIALS AND METHODS

Forty-eight animals were used for the experiment. The dogs were divided into four groups. In group A, the liver tissue was frozen to -80 degrees C and in group B, to -180 degrees C. Temperatures of -80 degrees C and -180 degrees C in contact with liver tissue was selected for cryosurgical exposure. For transmission electron microscopy, the specimens were taken immediately and 1 h after the finishing of the freeze-thaw cycles intraoperatively. Further, the next specimens were taken in 24 h, this time also intraoperatively.

RESULTS

The electronic microscopic analysis showed that, after local cryodestruction at temperatures of -80 degrees C and -180 degrees C, similar processes occurred within the liver tissue in the early postcryosurgical phase-immediately and 1 h after cryosurgical session. The hepatocytes in the center of the cryozone changed upon thawing. Ultrastructural changes in the hepatic cells, where the first signs of dystrophic processes had been noticed, were increased.

CONCLUSIONS

Our new insights prove on the cell level that suddenly and progressively damaged liver cells in the postcryosurgical zone lead to aseptic cryoaponecrosis and then to aseptic cryoapoptosis of vital normal tissue. The vascular capillary changes and circulatory stagnation demonstrate together with cryoaponecrosis and cryoapoptosis the anti-angiogenesis mechanisms, which are some of the main mechanisms of biological tissue injury following the low temperature exposure.

Cryoablation of liver tumours -- a review of mechanisms, techniques and clinical outcome

Several techniques exist for in situ destruction or ablation of liver tumours not eligible for resection. Cryoablation, i.e. the use of low temperatures to induce local tissue necrosis, was among the first of the thermal ablative techniques widely used. The procedures have typically been performed by surgeons during laparotomy, but recently minimally invasive cryoablation has been reported feasible. The present review focuses on mechanisms of tissue destruction, techniques of ablation including procedural monitoring, and clinical outcome following cryoablation of liver tumours. Plausible causes of tumour persistence at the site of ablation, i.e. local treatment failure, are discussed. Shortcomings exist in monitoring of the freezing process and may be a main cause. The evidence for the long-term outcome following liver tumour cryoablation needs to be improved. Cryoablation has been challenged by other techniques of tumour ablation such as radiofrequency ablation. Randomised trials against these modern techniques may define the role of cryoablation in the treatment of liver tumours. With improved imaging technology and patient selection, cryoablation of liver tumours may hold promise for selected patients.

Cryotherapy for liver tumors: current status, perspectives, clinical results, and review of literature

Cryotherapy has gained importance as a locally ablative treatment option for patients with non-resectable liver tumors, especially metastases from colorectal cancer. We have used this technique since 1996 for the treatment of 77 patients with malignant liver tumors. Patient data was prospectively recorded and follow-up was until September 2002 or death. Fifty-five patients had colorectal cancer liver metastases, 16 metastases from other primaries and 6 had hepatoma. Forty patients had cryotherapy only and 37 had an additional liver resection. Morbidity and mortality were 22% and 1.3%, respectively. In 68% of patients with colorectal liver metastases and an elevated serum carcinoembryonic antigen-level preoperatively, it returned to the normal range following cryosurgery. For all 77 patients, median survival was 28 months with a 3- and 5-year-survival rate of 39% and 26%, respectively, and median survival was 29 months with a 3- and 5-year-survival rate of 44% and 26%, respectively, for the 55 patients with colorectal liver metastases. Local recurrence at the cryosite was observed in 13 of 65 patients (20%) with initially complete treatment. For cryotherapy to further establish as a treatment for malignant liver tumors in a time where many new local ablative techniques are developing, different goals need to be achieved. The trauma of the procedure and local treatment failure need to be minimized and survival results need to be optimized. Published studies and new possible fields of research regarding these goals are discussed.

Image-guided ablation of renal cell carcinoma

An increasing number of small asymptomatic renal cell carcinomas (RCCs) are being detected by cross-sectional imaging. Because of the nonaggressive biologic behavior of many of these tumors, there is increasing interest in minimally invasive treatment modalities,particularly for the elderly, infirm, and patients with comorbid conditions. Radiofrequency(RF) ablation, cryoablation, microwave ablation, and laser ablation have all shown promise for the treatment of RCC, with high local control and low complication rates for RF ablation and cryoablation. However, the clinical trial data remain early, and survival data are not yet available for a definitive comparison with conventional surgical techniques for removal of RCC.

Advanced hepatic tissue destruction in ablative cryosurgery: potentials of intermittent freezing and selective vascular inflow occlusion

Recent studies indicate that cryosurgery represents a promising approach to treat non-resectable liver tumors. To improve parenchymal tissue destruction, a variety of modifications of the freeze-thaw procedure have been suggested, including repetitive freezing and portal-triad cross-clamping. The aim of the present study was to analyze whether intermittent freezing by application of a double freeze-thaw procedure or selective vascular inflow occlusion are more effective than a single freeze-thaw cycle to achieve complete hepatic tissue destruction. Using a porcine model, intrahepatic cryolesions were induced by freezing the hepatic tissue for a total of 15 min (n=6, SF). Additional animals (n=6) underwent a double freeze-thaw cycle of 7.5 min each (DF). A third group of animals (n=6) was treated by a single 15-min freeze-thaw cycle during selective vascular inflow occlusion (VO-SF). Seven days after freezing, DF did not change the volume of the cryolesion (25.4+/-1.7 cm(3)) compared to SF (29.9+/-3.7 cm(3)), however, resulted in enhanced destruction of hepatocyte nuclear morphology (DF-score: 2.4+/-0.2 versus SF-score: 1.1+/-0.3; p<0.05) and attenuated leukocyte infiltration within the margin of the cryolesion (DF-score: 1.5+/-0.2 versus SF-score: 2.8+/-0.1; p<0.05). VO-SF was also effective to significantly enhance destruction of hepatocyte nuclear morphology (2.8+/-0.1; p<0.05 versus SF), but, additionally, markedly increased the volume of the cryolesions (43.3+/-5.3 cm(3); p<0.05 versus SF and DF). Interestingly, VO-SF further increased the number of apoptotic cells, while leukocyte infiltration (2.3+/-0.3) was not affected compared to that after SF-treatment. Thus, our data indicate that both DF and VO-SF are effective to enhance parenchymal cell destruction within the margin of the cryolesion. VO-SF additionally increases the volume of the lesion and may therefore be most attractive for successful clinical application.

Significance of total vascular exclusion for hepatic cryotherapy: an experimental study

BACKGROUND

In the liver, efficacy of cryosurgical ablation of tumors located near the retrohepatic vena cava is impaired by the heat-sink effect. This could be overcome by total vascular exclusion (TVE) of the liver. In this study, the effect of TVE on cryosurgical ablation of liver tissue close to the retrohepatic vena cava was investigated with regard to the extent of the cryolesion and complications arising from necrosis of the caval wall.

METHODS

Of a total of 28 pigs, 14 underwent cryotherapy with TVE compared to 14 without TVE, both involving the vena cava. 7 animals in each group were subjected to one freeze cycle and 7 in each group to two freeze cycles. Temperatures in the cryolesion were monitored and cryolesions were documented sonographically. Laboratory parameters were determined pre- and postoperatively. Follow-up was 14 days. Morphology, extent of the cryolesion, damage to the vena cava and complications were assessed after autopsy.

RESULTS

With TVE, freezing rates were increased and cryolesions were significantly larger than without TVE. Transmural necroses of the vena cava with complete necrosis of the intima occurred significantly more frequently after TVE. Macro- and microscopically, the damage to the caval wall was considerably more marked after cryotherapy under TVE but in all cases the continuity of the vessel wall remained intact. There were no ruptures, thrombosis, or strictures of the vena cava.

CONCLUSIONS

The combination of cryotherapy and TVE increases the effectiveness of cryoablation in the liver involving the retrohepatic vena cava without any severe vascular complications occurring in the pig.

Hepatic vascular inflow occlusion enhances tissue destruction during cryoablation of porcine liver1

BACKGROUND

Local recurrences after cryoablation of liver tumors have been reported at rates from 5% to 44% and can be caused by inadequate coverage of the tumor by the frozen region. Hepatic vascular inflow occlusion may facilitate ablation by enlarging the size of the frozen region and the tissue necrosis induced by freezing. Few studies have documented these effects of inflow occlusion during liver cryoablation.

MATERIALS AND METHODS

Two cryolesions were induced in the liver of 12 pigs in a standardized set-up. Vascular inflow occlusion was used in six pigs during freezing. Two freeze cycles were performed at each location. Ice-ball volume was estimated by intraoperative magnetic resonance imaging. Cryolesion volume was estimated from histopathologic examination of the lesions 4 days after ablation.

RESULTS

The median volume of ice-balls produced during inflow occlusion was 107% larger than for ice-balls produced without occlusion (P < 0.001). The median volume of cryolesions made during inflow occlusion was 195% larger than for cryolesions induced without occlusion (P < 0.001). The geometry of the ice-balls was more regular if produced during inflow occlusion than if not. The ice-balls produced during the second freeze cycle were 17% and 20% larger than the ice-ball produced during the first freeze for lesions made with (P = 0.01) and without (P = 0.03) inflow occlusion.

CONCLUSIONS

Hepatic vascular inflow occlusion enables freezing of larger volumes of liver tissue andincreases the volume of tissue necrosis induced during cryoablation of porcine liver.

[Cryosurgery of primary and metastatic cancers of the liver]

Cryosurgery is a method of in situ destruction of tissue by a freezing process. Results of hepatic cryosurgery are now available for more than 2100 patients and allow to assess its place in the treatment of hepatic malignancies. Mechanisms of tissue destruction and indications of cryosurgery are detailed. With a peri-operative mortality rate of 1.5%, the safety of hepatic cryosurgery is now admitted. Cryosurgery has its own morbidity: increase of transaminases levels, platelets drop, myoglobinuria and rarely renal failure or cryoshock. In selected patients, hepatic cryosurgery is feasible with a laparoscopic or percutaneous approach. Long term results do not support cryosurgery as an alternative to liver resection. This technique enlarges possibilities of surgical treatment for patients with primary and metastatic liver cancers.

Magnetic resonance imaging-estimated three-dimensional temperature distribution in liver cryolesions: a study of cryolesion characteristics assumed necessary for tumor ablation

The goal of this study was to estimate the three-dimensional (3D) temperature distribution in liver cryolesions and assess the margin of the transition zone between the tumoricidal core of the lesion and the surrounding unfrozen tissue, using criteria proposed in the literature. Local recurrences after liver tumor cryoablation are frequent. Temperatures below -40 degrees C and a 1-cm zone of normal tissue included in the cryolesion are considered necessary for adequate ablation. The 3D temperature distribution in 10 pig cryolesions was estimated by numerical solution of a simplified bioheat equation using magnetic resonance imaging data to establish cryolesion border conditions. Volumes encompassed by the -20, -40, and -60 degrees C isotherms were estimated. The shortest distance from every voxel on the -40 degrees C isotherm to the cryolesion edge was calculated and the mean and the maximal of these distances were defined for each cryolesion. Median cryolesion volumes with temperatures of -20, -40, and -60 degrees C or colder were 53, 26, and 14% of the total cryolesion volume, respectively. The median cryolesion volume was 12.3 cm(3). The median of the mean distances calculated between the -40 degrees C isotherm and the cryolesion edge was 4.1 mm and increased with increasing cryolesion volume. The median of the largest of these distances calculated for each cryolesion was 8.1 mm. Temperatures claimed to be adequate for tumor destruction were obtained only in parts of the cryolesion. The adequacy of a 1-cm zone of normal liver tissue included in the cryolesion to ensure tumor ablation is questioned.

Haemobilia

BACKGROUND

This review aims to establish whether increased use of invasive procedures and the trend toward conservative management of major trauma has resulted in an increased incidence of haemobilia.

METHOD

A Medline (http://igm.nlm.nih.gov/)-based search of the English language literature from January 1996 to December 1999 inclusive was performed using the keywords haemobilia, hemobilia, haematobilia and hematobilia. The presentation, aetiology, investigation, management and outcome of 222 cases were reviewed.

RESULTS

Two-thirds of cases were iatrogenic while accidental trauma accounted for 5 per cent. Haemobilia may be major, constituting life-threatening haemorrhage, or minor; it may present many weeks after the initial injury. Diagnosis is most commonly confirmed by angiography. Management is aimed at stopping bleeding and relieving biliary obstruction; 43 per cent of cases were managed conservatively and 36 per cent were managed by transarterial embolization (TAE). Surgery was indicated when laparotomy was performed for other reasons and for failed TAE. The mortality rate was 5 per cent.

CONCLUSIONS

Although the incidence of iatrogenic haemobilia has risen considerably, the bleeding is often minor and can be managed conservatively. When more urgent intervention is required, TAE is usually the treatment of choice. There is no evidence that the conservative management of accidental liver trauma increases the risk of haemobilia.