Outer-Surface Approach
Epicardial Ablation
Some arrhythmias originate on the outer surface of the heart, out of reach from the inside. Epicardial ablation reaches that surface through the pericardial space, and is used in selected, mostly ventricular, cases.
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Understanding the Approach
What Is Epicardial Ablation?
Most catheter ablation is carried out from inside the heart chambers, treating the inner surface, the endocardium. The heart wall has layers, and in some conditions the arrhythmia circuit lies in the outer layer, the epicardium.
In epicardial ablation, a catheter is placed into the thin space around the heart, the pericardial space, so the outer surface can be mapped and treated.
It is a specialised addition to standard catheter ablation and is only used when a clear reason exists.
Indications
When It May Be Considered
Ventricular tachycardia from an epicardial origin
Some scar-related and idiopathic VT arises on the outer surface and cannot be fully treated from inside.
After an unsuccessful endocardial attempt
If mapping suggests the circuit lies outside the reach of inner-surface ablation.
Certain cardiomyopathies
Some forms of heart muscle disease produce arrhythmias with predominantly epicardial substrate.
Suitability depends on ECG and imaging findings, previous cardiac surgery and the individual anatomy.
The Procedure
How Access Is Obtained
The procedure is typically performed in specialised centres, often under general anaesthesia or deep sedation.
Planning
Imaging and 3D mapping decide whether an epicardial approach is needed.
Access
A needle is guided below the breastbone into the pericardial space under imaging, and a catheter is passed through it.
Mapping
The outer surface is mapped and the position of coronary arteries and the phrenic nerve is checked.
Ablation
Energy is applied where safe, away from critical structures.
Completion
The access is managed and the patient monitored for bleeding or inflammation.
Context
Relationship to Endocardial Ablation
Epicardial ablation is usually an addition to, not a replacement for, mapping and ablation from inside the heart. Most procedures begin with the inner surface, and the epicardial approach is added when findings or earlier results suggest a source on the outer surface.
Both surfaces may be mapped in the same procedure. Whether epicardial access is needed is sometimes decided beforehand from the ECG and imaging, and sometimes during the procedure. See VT Ablation and Catheter Ablation.
Safety
Benefits and Risks
Epicardial ablation can make it possible to treat arrhythmias that endocardial ablation cannot reach.
It is more demanding than conventional ablation and is only appropriate when expected benefit justifies the additional risk.
Specific risks include bleeding into the pericardial space, which may need drainage, pericardial inflammation and rarely injury to coronary vessels or the phrenic nerve.
Your electrophysiologist will explain which risks apply to you.
Safety
Specific Risks and How They Are Managed
Bleeding into the pericardial space
The access needle or catheter can injure a small vessel or the heart wall, causing bleeding around the heart. If the blood collects and presses on the heart (cardiac tamponade), it may need to be drained. The team watches for this during and after the procedure and is prepared to treat it.
Pericardial inflammation
The lining around the heart can become irritated, causing chest discomfort that may be worse when breathing in or lying flat. It is monitored and treated as needed.
Injury to surrounding structures
The phrenic nerve and coronary arteries lie close to the outer surface of the heart, and nearby structures can rarely be injured during access. Imaging of the coronary arteries and checking the position of the phrenic nerve are used to reduce this risk, and energy is not applied where it would be unsafe.
After discharge
Report increasing chest pain, fever, breathlessness or faintness promptly. Follow-up covers rhythm, heart function and the underlying condition.
After the Procedure
Recovery and Follow-Up
Patients are usually observed for a longer period than after routine ablation, and may have chest discomfort related to pericardial irritation.
Follow-up focuses on rhythm control, heart function and the underlying disease.
Questions
Frequently Asked Questions
Is epicardial ablation open-heart surgery?
Who needs this approach?
Is it done as a first-line option?
Is it painful?
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