Percutaneous Epicardial Access for Ventricular Tachycardia After Bypass Surgery

Ventricular tachycardia (VT) in a patient with previous coronary artery bypass grafting presents a distinctive electrophysiology problem. Ischaemic scar may involve the subendocardium, intramural myocardium, and epicardial surface, while the operation itself can create dense pericardial adhesions. A catheter route that is routine in an untouched pericardium may therefore become hazardous after median sternotomy.

Percutaneous epicardial access can provide essential mapping and ablation options when endocardial treatment cannot reach the clinical substrate. The procedure requires detailed anatomical planning, careful needle and wire control, appropriate anticoagulation timing, and immediate access to surgical or interventional rescue. Patient selection should be discussed by an experienced ventricular arrhythmia team rather than decided during an unexpectedly difficult endocardial procedure.

Selecting patients and defining the substrate

The strongest indication is recurrent monomorphic VT, electrical storm, or implantable cardioverter-defibrillator (ICD) therapy in which imaging, prior ablation, or electrocardiographic features suggest an epicardial component. Inferolateral and inferobasal infarct scars are common areas of concern, although the distribution depends on the original coronary disease, graft patency, infarct territory, and subsequent remodelling. A failed endocardial ablation does not automatically prove that epicardial access will succeed; it should prompt a review of the mechanism, lesion depth, and procedural risk.

Preprocedural imaging should combine contrast-enhanced cardiac CT or magnetic resonance imaging with coronary angiography when appropriate. CT can identify the position of the right ventricle, left ventricular apex, diaphragm, liver, stomach, sternum, and bypass grafts in relation to the intended puncture path. The operative report is valuable: the location of a left internal mammary artery graft, saphenous vein graft anastomoses, prior pericardial openings, and any documented postoperative complications may change the access plan.

Risk assessment should include ventricular function, renal function, pulmonary disease, anticoagulant use, platelet count, and the likelihood of needing mechanical circulatory support. Structured approaches to clinical risk assessment are also relevant to arrhythmia care; the Journal’s Shanghai score story is a useful example of how a risk tool can support, rather than replace, specialist judgement. The Shanghai score is not a substitute for VT-specific planning, but it reinforces the value of documenting the clinical context behind an invasive decision.

Planning the percutaneous route after sternotomy

The usual route is subxiphoid, using a long needle directed toward the left shoulder or left midclavicular region under fluoroscopic and, where available, ultrasound guidance. The operator seeks a shallow trajectory beneath the xiphoid or lower costal margin, avoiding the liver and the right ventricle. A soft-tipped guidewire should enter the pericardial space freely before dilation and sheath placement. Small-volume contrast injection can confirm an extravascular, nonmyocardial position, although contrast patterns must be interpreted cautiously in an altered pericardium.

Previous bypass surgery can obliterate the accessible pericardial space. Adhesions may tether the heart to the sternum, diaphragm, or posterior tissues, leaving no broad fluid-filled plane for a guidewire to occupy. The needle may enter myocardium, a loculated pocket, or a narrow tract between adhesions. Repeated probing increases the risk of lacerating the right ventricle or a graft. A low threshold for stopping, obtaining additional imaging, or involving a cardiac surgeon is safer than escalating blind needle manipulation.

Some centres use a surgical subxiphoid window or limited thoracoscopic approach when percutaneous access is considered unsuitable. This may permit controlled adhesiolysis and placement of an epicardial sheath, although it converts a catheter procedure into a surgical intervention with its own anaesthetic and wound-related risks. A hybrid strategy can be particularly useful when the expected ablation target is lateral or posterolateral and the patient has extensive anterior adhesions.

Mapping and ablation in a scarred pericardium

Once access is established, a steerable sheath and multipolar catheter can define the epicardial substrate. Mapping should cover areas of low voltage, abnormal electrograms, late potentials, fractionation, and diastolic activity during tachycardia or pacing. Epicardial signals may be attenuated by fat, and the presence of epicardial adipose tissue can produce apparently low voltage without representing ablatable scar. Integration with CT or MRI helps distinguish fat, scar, coronary arteries, and phrenic nerve territory.

A combined endocardial–epicardial strategy is frequently necessary. The operator should compare activation, pace maps, entrainment findings, and unipolar abnormalities rather than treating every epicardial abnormality. Epicardial ablation near a coronary artery requires angiographic definition of the vessel and an adequate safety margin. Radiofrequency delivery close to a graft, native coronary artery, or phrenic nerve may cause irreversible injury. High-output pacing can help identify phrenic nerve capture, but a negative test is not an absolute guarantee of safety.

Irrigated radiofrequency energy is commonly used, with power and duration adjusted for tissue thickness, impedance, proximity to structures, and the risk of steam formation. Excessive energy can damage the myocardium or nearby organs, while inadequate energy may leave deep channels untreated. After ablation, repeat mapping and programmed stimulation should be interpreted alongside the clinical endpoint, since inducibility can be affected by anaesthesia, autonomic tone, haemodynamics, and antiarrhythmic medication.

Recognising and managing complications

Bleeding is the most immediate concern during epicardial puncture. It may result from right ventricular injury, coronary or graft trauma, diaphragmatic vessels, or a laceration concealed by adhesions. A small pericardial effusion can enlarge gradually, especially after systemic heparin is given for endocardial mapping. Continuous haemodynamic observation, repeated echocardiography, and a clear plan for pericardial drainage are essential. In a deteriorating patient, the team must distinguish tamponade from VT-related shock, anaesthetic hypotension, or right ventricular ischaemia without delaying treatment.

Coronary artery injury, graft damage, and phrenic nerve palsy are particularly important after bypass surgery. A left internal mammary artery graft may lie close to the anterior epicardium, while vein grafts can cross regions that appear suitable for ablation. Coronary angiography before energy delivery should be considered when the target is near a vessel. Phrenic nerve mapping and mechanical displacement with air or fluid may reduce risk in selected cases, but displacement techniques are not uniformly effective and can introduce additional complications.

Other recognised problems include pericarditis, pleuropericardial bleeding, pneumothorax, peritoneal entry, liver or gastric puncture, infection, and persistent pain. Epicardial access should be reassessed before sheath removal, with removal performed in a controlled setting after haemostasis and reversal of anticoagulation when clinically appropriate. A pericardial drain is often retained when bleeding risk is material. Postprocedural echocardiography, serial haemoglobin measurement, renal monitoring, and observation for recurrent VT help detect complications that may emerge after the laboratory procedure.

Building an Australian service pathway

In Australia, advanced epicardial VT ablation is concentrated in tertiary electrophysiology services, including major centres in Sydney, Melbourne, Brisbane, Adelaide, and Perth. Patients from regional and remote areas may travel long distances for imaging, consultation, and follow-up, so the referral plan should include local cardiology contacts, ICD interrogation arrangements, and a clear pathway for urgent readmission. The public hospital system and private sector may have different scheduling, funding, and access arrangements, making early coordination important.

Local procurement also influences technique. Mapping platforms, contact-force irrigated catheters, epicardial sheaths, coronary imaging facilities, anaesthetic support, and surgical backup may not be available at every hospital. Australian teams should verify product registration and institutional approval through the Therapeutic Goods Administration framework, as well as local stock and training requirements. A technically attractive approach is of limited value if the required catheter, imaging capability, or rescue service cannot be reliably provided.

Multidisciplinary preparation should include electrophysiology, cardiac anaesthesia, cardiothoracic surgery, imaging, intensive care, and nursing staff. Preprocedure conferences are especially valuable for patients with prior sternotomy, patent grafts, severe left ventricular dysfunction, or a history of electrical storm. The Journal’s special issues provide a useful route to focused literature on ventricular arrhythmia, ablation, devices, and related electrophysiology practice for teams developing local protocols.

Prospective registries and detailed procedural reporting can clarify which patients benefit from a percutaneous approach after bypass surgery and which should proceed directly to a hybrid or surgical strategy. Reports should describe imaging, access attempts, adhesions, graft anatomy, energy delivery, complications, drain management, and late outcomes. These details help Australian services compare practice across metropolitan hospitals and support safer referral pathways for patients outside the major cities.

For clinicians and researchers developing or evaluating an epicardial VT programme, the Journal offers a platform for clinically relevant studies, technical reports, reviews, and guidelines. Review the author guidance before preparing a submission, and use complete procedural descriptions so that readers can assess both the effectiveness and the risks of the technique.