Washington University in St. Louis hepatobiliary-pancreatic and gastrointestinal (HPB-GI) surgeons offer a treatment called irreversible electroporation (IRE) for patients with liver tumors considered inoperable because of their location near delicate structures like major blood vessels or bile ducts.
IRE involves placement of electrodes around a tumor and using high-voltage direct current to create holes in the cell membrane to irreversibly damage cancer cells, while leaving surrounding veins, nerves and ducts largely unaffected. With the cancer cells destroyed, healthy tissue can then grow and repopulate the area.
This procedure offers an alternative to patients when radiofrequency (RF) ablation, cryotherapy (freezing tissue) or open surgery are considered too risky.
How IRE Works
At the beginning of the IRE procedure, an MRI is used to locate the tumor specifically within the liver. Then, with the patient under anesthesia, the liver is surgically exposed to place the needle electrodes in the correct locations under ultrasound guidance. The needles must be at a specific depth, parallel to each other and a specific distance apart. From three to five needles are used, depending on the size and configuration of the tumor, so mostly cancer cells are killed and nearby healthy tissue is spared.
Once the electrodes are placed, the surgeon inputs the information into a machine, which confirms correct placement. Delivery of the electrical current is then done automatically by the machine at a specific time, coordinated with the patient’s EKG pattern and heartbeat.
The current is delivered during the 10 millisecond period of cardiac rhythm rest to avoid interfering with the heart’s electrical system. By treating during this refractory period, the current cannot go down the heart and interfere with normal heart rhythms.
Delivery of the current takes about 10 to 15 minutes, but the whole surgical procedure can take a couple of hours. Six weeks after IRE, the patient has another MRI to confirm tumor destruction.
IRE can be used in any part of the liver.
Contraindications for IRE
Patients who aren’t eligible for IRE fall into several categories:
- Those whose tumors are too large or who have many tumors
- Those who have implanted pacemakers or defibrillators, devices not currently included in FDA approvals
- Those who have very fast or irregular heartbeats: Because of the safety factors built into the system, if it can’t detect the heart signal and identify the refractive period, either because the heartbeat is erratic or too fast, the machine won’t deliver the current.
Our surgeons also perform IRE for pancreatic tumors using the same method as for liver tumors. Locally advanced tumors that have failed first-line therapy may be considered for pancreatic IRE
Washington University HPB-GI surgeons who perform IRE:
Steven M. Strasberg, MD
For physicians to refer a patient, or to make an appointment, call 314-362-7147.