A first-in-human trial finds that gallbladder cryoablation to be a promising alternative to long-term cholecystostomy tube drainage for the treatment of cholecystitis in non-operative patients. Presenting this research at the Society of Interventional Radiology (SIR) annual conference (23–28 March, Austin, USA), Hugh McGregor (University of Arizona, Tucson, USA) informed attendees that the minimally invasive treatment may facilitate safe cholecystostomy tube removal in this patient population.
“Gallbladder cryoablation is something we have been working on over the past five years. We have been able to take the idea from conception to animal models, and finally [now] into the clinical realm,” McGregor said.
Gall stone disease affects 20 million patients in the USA, with over 300,000 cholecystostomies performed each year nationally. McGregor explains that “unfortunately, complication rates in elderly and infirm patients can be as high as 31%, and this necessitates percutaneous cholecystostomy as an alternative treatment. This itself is not definitive, with a recurrence rate of calculous cholecystitis up to 46% following tube removal. This leaves high risk patients with gall stone disease with three options: they undergo high risk cholecystectomy, they have their tube removed with a moderate to high risk of recurrent cholecystitis, or they have a tube for life. We all know this [a tube] needs constant, regular changes, and is not good for quality of life. There is definitely a need for a novel treatment option for these patients.”
This was therefore the aim of McGregor et al’s study: seeking an alternative treatment option. Following successful pre-clinical trials in swine models, which proved the safety and efficacy of gallbladder cryoablation, the Arizona investigators set out to determine the procedure’s safety and efficacy in humans.
The first patient treated was a 71-year-old man with obesity, chronic obstructive pulmonary disease, diabetes and ischaemic heart disease. He was admitted for acute calculous cholecystitis and, following surgical consultation, was given a cholecystostomy tube, placed under CT guidance. He was discharged after four days in hospital, and a week after discharge was seen by the interventional radiology team. Twenty-four days after his initial discharge, he underwent CT-guided gallbladder cryoablation with moderate sedation.
This gallbladder cryoablation was successfully performed under CT guidance using three PCS-24 cryoprobes. Two 19-gauge Yueh needles were inserted percutaneously under CT guidance to facilitate hydrodissection of the transverse colon and duodenum. A total of 1,260ml of normal saline was used for hydrodissection. A 10-8-10 minute freeze-thaw cycle with intermittent CT was used to ablate the gallbladder and achieve 5mm ablation margins. The cholecystostomy tube was removed immediately after the procedure, and the patient was discharged one day after the cryoablation with a 10-day course of moxifloxacin.
According to McGregor, laboratory values on post-procedure day 28 were notable for a mildly elevated alkaline phosphatase of 167IU/L, which normalised by three months. An MRI enhanced with the contrast agent eovist at 28 days’ post-procedure demonstrated a thick gall bladder wall with a persistent lumen, a patent common bile duct, and no filling of the cystic duct. MRI at three-months’ post-procedure showed partial collapse of the gall bladder, with early and delayed enhancement suggestive of ongoing inflammation and fibrosis. McGregor described how the imaging at six-months follow-up “really nicely demonstrated the continued involution of the gall bladder”, which then had no lumen: “it is just a completely involuted, collapsed structure, really a scar”. The patient was asymptomatic at all follow-up times.
Summarising this clinical work, McGregor said to the SIR audience: “This is one case, but we feel it may be a promising option for high-risk, tube dependent patients with gall stone disease. Our imaging follow-up demonstrated cystic duct occlusion, as well as involution of the gall bladder, and clearly studies are need to establish the safety and efficacy of the procedure, particularly in patients with bulky gall stone disease. Those are in the pipeline.”
Recently, McGregor and colleagues performed gallbladder cryoablation on a woman with a single large gall stone, and one-month imaging (the latest follow-up imaging available) is promising, with the patient currently asymptomatic. McGregor said at SIR that he is “looking forward to her further follow-up imaging”. To date, the investigators have performed gallbladder cryoablation on five patients, though only the first patient’s experience was presented at SIR.
The procedure involved the off-label use of an FDA approved device, and McGregor disclosed that several authors of the study have a patent pending for a cryoablation device.
Fielding a question from the audience asking how the patient felt following the procedure, McGregor explained: “He [the first patient] was a pretty stoic guy. According to him, he felt great. He was hungry, he wanted to eat immediately afterwards; we kept him in NPO [nil per os] because we were a little concerned about that duodenum there on the first case. But he felt great. We followed him up every day for a week afterwards, and really, there were no complaints.”