Cryoablation is a medical procedure that destroys targeted tissue by freezing it. A thin probe delivers extremely cold gas directly into unwanted tissue, forming an ice ball that kills cells through a combination of ice crystal damage and fluid shifts. It’s used to treat certain cancers, heart rhythm disorders, and other conditions where tissue needs to be precisely eliminated without traditional surgery.
How Freezing Destroys Tissue
The procedure works through two connected phases: freezing and thawing. During freezing, the probe pulls heat out of the surrounding tissue, and ice crystals begin forming in the space between cells. These crystals lock up free water, which makes the fluid outside cells much saltier than the fluid inside them. Water gets pulled out of cells to equalize the difference, dehydrating them and concentrating the chemicals inside to toxic levels. This damages internal cell structures and destabilizes the cell membrane.
When cooling happens rapidly, things get even more destructive. Water gets trapped inside cells before it has time to move out, forming ice crystals directly within the cell. These crystals physically tear through internal membranes, killing cells almost immediately.
The thawing phase does its own damage. Extracellular ice melts first, creating the opposite problem: now the space outside the cell is more dilute. Water rushes back into already-damaged cells, causing them to swell and burst. That incoming water can also feed the growth of any remaining intracellular ice crystals, compounding the destruction. This freeze-thaw cycle is typically repeated to maximize cell death in the targeted area.
The Technology Behind the Probe
Modern cryoablation systems use argon gas and a principle from physics called the Joule-Thomson effect. When argon gas is released from high pressure through a tiny opening at the tip of the probe, it expands rapidly and drops in temperature. The higher the starting pressure, the colder the tip gets, the faster temperatures drop, and the larger the resulting ice ball. Doctors can control the size and shape of the frozen zone by adjusting gas pressure and probe placement, which allows them to target tumors or other tissue with precision while limiting damage to surrounding structures.
The probes themselves are needle-thin, often guided into position using real-time imaging like CT scans or ultrasound. Because the ice ball is visible on these scans, the medical team can watch the treatment zone form in real time, something that isn’t possible with heat-based alternatives.
What Cryoablation Treats
Cryoablation has two major areas of use: cancer treatment and heart rhythm correction.
In oncology, it’s used for tumors in the kidneys, liver, lungs, prostate, and bone. It tends to be offered for smaller, localized tumors, particularly when a patient isn’t a good candidate for open surgery. For prostate cancer, the vast majority of procedures (over 75%) are used as a primary treatment rather than a salvage option after other therapies have failed.
In cardiology, cryoballoon ablation has become a mainstream treatment for atrial fibrillation. Instead of a needle-like probe, a balloon catheter is threaded into the heart and inflated at the openings of the pulmonary veins, freezing the tissue that triggers abnormal electrical signals. This creates a ring of scar tissue that blocks those signals from reaching the rest of the heart.
Cryoablation vs. Radiofrequency Ablation
The main alternative to cryoablation is radiofrequency ablation, which uses heat instead of cold to destroy tissue. For atrial fibrillation, a large meta-analysis found the two approaches produce nearly identical results: 47% of patients in both groups remained free of atrial fibrillation at 12 months or longer. Procedure times are also similar, averaging around 162 minutes for cryoballoon and 166 minutes for radiofrequency, a difference that isn’t statistically meaningful.
Where they differ is in practical tradeoffs. Cryoablation’s ice ball is visible on imaging during the procedure, giving the medical team a real-time view of the treatment zone. Cryoablation also tends to cause less pain during the procedure itself, since cold has a natural numbing effect. On the other hand, cryoballoon ablation carries a higher risk of phrenic nerve injury, the nerve that controls your diaphragm. Early studies reported this complication in 4% to 11% of cardiac cryoablation patients, though newer monitoring techniques have brought that rate down to around 1%.
What the Procedure Feels Like
Cryoablation is minimally invasive. For cancer treatment, one or more thin probes are inserted through the skin and guided to the target using imaging. The procedure is done under anesthesia, so you won’t feel the freezing itself. Depending on the location and complexity, you may go home the same day or stay overnight in the hospital.
Afterward, expect some soreness and bruising at the probe insertion site for several days. Most people return to their usual activities within a few days. A subset of patients, particularly after kidney tumor cryoablation, develop what’s called post-ablation syndrome: low-grade fever, fatigue, muscle aches, and nausea that typically peaks in the first one to two days. Patients who develop fever tend to experience more pronounced flu-like symptoms overall, but these resolve on their own within about 10 days.
Risks and Limitations
Cryoablation is generally considered safe, but it carries risks that vary by treatment site. For cardiac cryoballoon procedures, phrenic nerve injury is the most notable concern. The phrenic nerve runs close to the veins being treated, and freezing can damage it, potentially affecting breathing on one side. Most cases resolve over weeks to months, but permanent injury, marked by irreversible tissue damage, is possible in rare cases.
For tumor treatment, risks include bleeding, infection, and damage to nearby organs or nerves depending on the probe’s location. Because the frozen zone extends in all directions from the probe tip, structures adjacent to the target can sustain unintended injury. The visibility of the ice ball on imaging helps mitigate this, but it doesn’t eliminate the risk entirely.
Cryoablation also has size limitations. It works best on smaller, well-defined targets. Larger tumors may not freeze completely, leaving viable cells at the margins. For this reason, it’s typically reserved for tumors under a certain size threshold, which varies by organ and clinical judgment.