Stanford Cardiac Arrhythmia Service

Epicardial Ablation

Epicardial ablation – or ablation of cells on the outside the heart muscle – is used when standard catheter ablation from inside the heart is not successful in identifying the region of heart tissue responsible for the heart rhythm problem and the critical region of heart tissue is found to be on the outside of the heart.  

How it works

In order to perform catheter ablation on the outside of the heart, it is first necessary to find a route to the outside of the heart without requiring surgery.   The most direct and safest route to the space outside the heart is the region just under the breastbone at the bottom of the rib cage.  A special needle that is selected to make entry as safe as possible, is used. This needle enters to space around the heart- the space is called the pericardial space since the pericardium is the sack surrounding the heart.  A special wire is inserted into the pericardial space and the needle is removed and a plastic tube is inserted over the wire.  This plastic tube is used during the procedure to allow the ablation catheter to be safely inserted into the pericardial space.  Once the ablation catheter is positioned in the pericardial space the exact site of the heart rhythm problem may be identified from the outside of the heart and it treated with ablation. 

Following epicardial ablation, often a small plastic tube like a long intravenous catheter may be left in place overnight to drain any fluid that may accumulate in the pericardial space. It is removed as soon as this drainage becomes minimal.  Patients may experience chest discomfort after the epicardial ablation because some degree of irritation of the pericardium, called pericarditis, usually occurs.  Patients are often given medications that reduce the degree of pericarditis.

Selecting patients for epicardial ablation

Most patients being considered for epicardial ablation have already had an attempted catheter ablation procedure.  During this ablation there is usually evidence that the arrhythmia focus is not located on the inside of the heart.   In some patients there may be ECG clues that the focus is more likely to be epicardial in location.   Statistically most heart rhythm problems originate closer to the inside of the heart, a major reason that standard catheter ablation from within the heart is attempted first.  Patients with ventricular tachycardia without coronary artery disease are statistically frequently found to have the heart rhythm problem on the outside of the heart.   When considering all ablation procedures, supraventricular tachycardias are least likely to be treated epicardially and a modest number of ventricular tachycardias are treated epicardially.  At most centers, epicardial ablation is not usually performed and selected centers, including Stanford, have the greatest experience with the technique. 

For patients with prior heart surgery, such as coronary artery bypass surgery (CABG) or heart valve surgery, the procedure for epicardial ablation must be modified.   Because patients develop significant fibrous tissue due to healing after heart surgery, the standard approach to obtaining access to the pericardial space is usually not possible.  In these cases, a cardiac surgeon works with the cardiac electrophysiologist performing the catheter ablation in order to create an opening to the pericardial space.  The same site of access, the region under the breastbone at the bottom of the rib cage, called the subxiphoid region, is used for the surgical access. Once the access is obtained, a plastic tube is inserted and the epicardial catheter ablation is performed in the same manner as other epicardial ablations.   This combination of a surgical approach and epicardial approach has been performed only at selected centers including Stanford.  The team at Stanford was the first to report use of a irrigated tip radiofrequency ablation catheter with this combined surgical-epicardial ablation procedure.

 

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