Cardiac Cryoablation – Atrial Fibrillation

Anesthesia Implications

Position: Supine, arms tucked
Time: 2-4 hours (long)
Blood Loss: Low (10-50 ml)
Post-op Pain: Zero
Maintenance Paralytic: Ask surgeon

Apply an arterial Line – standard for these cases to monitor for tamponade/hemodynamic instability.

Apply an esophageal temperature monitor – standard for these cases. Because the esophagus can be very close to where cryoablation will be taking place, the doctor is going to want to know if there are sudden changes in the esophageal temperature.

Two large-bore IV’s – ideal in the event the surgeon perforates the heart/over-cauterizes and tamponade ensues. If this happens and large-bore IVs are not present, don’t waste time starting them! Open the fluids and help correct pressures with drugs (ephedrine and phenylephrine).

Patient must remain motionless – Ask the surgeon if paralytics are ok. Phrenic nerve monitoring may be performed by the surgeon and, if this is the case, the surgeon will not want paralytics INITIALLY. The patient may be paralyzed after phrenic nerve monitoring.

Heparin and ACTs – Heparin is regularly given followed by an ACT. Be aware of puncture sites and possible hematomas

Be careful with phenylephrine drips – these can mask the signs of tamponade.

If tamponade occurs – avoid the use of phenylephrine to correct pressures. Use ephedrine or epinephrine. If absolutely necessary, the venous introducers at the groin can be utilized to give fluids. Protamine will be used to reverse the heparin (1 mg/100 u of Heparin previously administered. Give SLOWLY). Blood removed via pericardiocentesis will be reinjected via the femoral line. If bleeding persists (doesn’t clot) an emergency repair of the perforated atrium will have to be performed.

Tucked Arms (general considerations): Consider a second IV – once the procedure has started, it’s going to be VERY difficult to handle IV issues – especially if your only IV has problems. Ensure the IV is running and monitors are still functioning after tucking the patient’s arms

Long procedure (general considerations): Procedures anticipated to last longer than 2 hours generally require a urinary catheter. Also consider checking lines and positioning regularly as the risks of infiltration and nerve damage are increased with procedure time. Consider an IV fluid warmer and a forced air warmer to keep the patient euthermic.

Of the three types of atrial fibrillation (paroxysmal, persistent, and chronic), this procedure is performed for those who have the paroxysmal or persistent type.

After the patient is sedated and monitors applied, the doctor will insert a catheter at the level of the groin to access the femoral vein. The catheter will be threaded through the vein until it reaches the right atrium. The atrial septum will then be punctured to access the left atrium.

The heart will be mapped, locating the ostium (openings) of each of the four pulmonary veins. The ostium of each of the veins will be occluded with a balloon. This is followed by refrigerant being added to the inflated balloon. This “cryoablates”, or freezes the tissues, allowing them to scar and stop the electrical current causing the atrial fibrillation.

The advantage of cryoablation is that while cooling the tissues, the doctor can see whether or not those pathways are responsible for the atrial fibrillation. If not, the tissue is allowed to go back to a normal temperature. Otherwise, the tissue is ablated. This allows for a more precise ablation.