Principle
Irreversible electroporation (IRE), also known as "nanoknife" treatment, is a minimally invasive ablation method, which destroys tumors using intense bursts of electricity through two- to six-needle electrodes operating in pairs. The electricity causes nano-sized perforations on the membrane of tumor cells, causing a loss of homeostasis. The cells undergo apoptosis and the affected area immediately becomes necrotic. The current flow field is limited by the position and distance between positive and negative electrodes as well as the voltage strength; therefore, the ablation zone remains relatively consistent as long as the treatment conditions remain unchanged. This means that the region peripheral to the ablation zone is largely unaffected and the margin between the two regions is well-defined. Thermal therapy and cryotherapy are unable to achieve this level of specificity. IRE provides unprecedented security when the ablation zone is near important blood vessels or tissues. Unlike thermal and cryotherapy, IRE can be used to treat most organs including the pancreas without causing damage to the intestines, blood vessels, or bile ducts.

Electrode needles are inserted into the body using imaging guidance while the patient is under general anesthesia. The number of needles depends on the volume of the tumor. IRE has been approved by the US FDA for clinical applications as well as EU CE certification. By 2012, more than one hundred cancer hospitals were using this approach for the treatment of lung, kidney, pancreas, and prostate cancers.
 

Benefits of IRE
IRE provides an alternative for patients unable to endure surgery or other conventional ablation due to the proximity of tumors to vital organs or major blood vessels. High-voltage electrical pulses are less likely than thermal treatment or cryotherapy to damage adjacent normal tissues and there is no heat sink effect. The area affected by the charge presents a clear boundary within the distance of one to two cells. The immune system automatically begins clearing apoptotic cells and promoting the regeneration and repair of normal tissues. Tumor lesions can disappear within a few months.
 

Limits of IRE
Electric shocks induced by IRE can induce severe muscle twitching, which can lead to muscle dissolution and kidney failure. Thus, patients are generally given general anesthesia and/or administered drugs to paralyze muscles during treatment. Patients that are unable to undergo general anesthesia are deemed unsuitable for IRE. Every electric shock must be synchronized with the patient's heartbeat, however; this can still lead to arrhythmia or hypertension. Thus, patients with cardiovascular disease, irregular heartbeat, and/or severe hypertension face elevated risk under IRE treatment. Patients with implanted metal objects, such as pacemakers and metal stent implantation, are not candidates for IRE treatment.
 

When to use

1. IRE is used in cases where conventional ablation treatment is inapplicable due to the proximity of tumors to large blood vessels or vulnerable pipeline structures, such as bile ducts, pancreatic ducts, the ureter, or urethra.
2.  IRE is commonly used to treat cancers of the liver, biliary tract, kidney, pancreas, and prostate. Some foreign experts have also used IRE for the treatment of thyroid, breast cancer, and lung cancer.
    

Preoperative considerations of IRE

1. Regular testing of blood, liver and kidney function, and coagulation.
2. Electrocardiogram testing and urinalysis.
3. Patients who receive the CT-guided procedure may need to undergo transcatheter arterial embolization to facilitate positioning. It is not required for patients who receive the ultrasound-guided procedure.
4. Consent forms.
5. Fasting for at least six hours prior to treatment
    

Intraoperative considerations of IRE

1. IRE is performed under general anesthesia and requires the use of muscle relaxants.
2. IRE requires the use of a synchronizer in conjunction with the close monitoring of heart rate and rhythm as well as blood pressure throughout the operation.
3. Use of ultrasound-guided or CT-guided procedures as needed for treatment.
4. Selection of percutaneous treatment, endoscopic therapy, or conventional surgical treatment.
    

Postoperative considerations of IRE

1. Patients that undergo percutaneous treatment should lie down or lie on one side for at least six hours to facilitate hemostasis. This is not necessary for patients that undergo endoscopic or conventional surgery.
2. Patients that undergo percutaneous treatment may begin drinking or eating six hours after treatment. They must continue fasting if vomiting ensues and/or they feel discomfort. Patients that undergo endoscopic or conventional surgery should follow the advice of their physician with regard to the intake of food and liquids.
3. It is normal for a portion of the wound to be painful and/or exhibit signs of bleeding. If the pain becomes too severe, a physician or nurse should be contacted for advice.
4. Routine tests of blood and inflammation should be reviewed the following day to check for complications.
5. The gauze covering the percutaneous wound may be removed after 24 hours.
6. IRE requires the monitoring of cardiac enzymes as well as urinalysis and ECG monitoring 24 hours after treatment.
    

Risks and Complications
The complications of treatment are correlated with the treated organs. Common complications including postoperative bleeding, arrhythmia, hypertension, local infection, and metabolic acidosis. Currently, the number of patients undergoing this treatment is too low to provide reliable statistics with regard to the proportion of complications; however, IRE is generally considered safe.​