Substrate and Circuit Ablation
VT Ablation
Catheter ablation for ventricular tachycardia aims to treat the area of heart tissue that sustains the rhythm. It is used alongside medicines and, where needed, an implantable defibrillator, and is planned individually.
On this page
Rationale
The Role of Ablation in VT
Ventricular tachycardia (VT) may arise in a heart that is structurally normal or in a heart with scar from a previous heart attack, cardiomyopathy or other disease. These situations differ greatly, and so does the role of ablation.
In some people with VT from a single focus in a normal heart, ablation may be a primary treatment. In patients with structural heart disease, ablation is often used to reduce the number of episodes and ICD shocks, usually in combination with medication and, where indicated, an ICD.
Ablation is not a substitute for an ICD in patients who need one for protection from dangerous rhythms.
Two Broad Situations
Which VT Is Being Treated?
Idiopathic VT
Occurs without structural heart disease and often originates from a specific location such as the outflow tract. A focused ablation may be possible.
Scar-related VT
Uses re-entry through channels of surviving tissue within scar. Mapping aims to identify and modify the critical areas, often with substrate-based techniques.
Other mechanisms
Fascicular and papillary muscle VT, and VT linked to inherited or inflammatory conditions, each require tailored strategies.
Indications
When Ablation May Be Considered
Recurrent VT despite medicines
When episodes keep returning, or medicines are not effective or not tolerated, ablation may be discussed as part of the overall plan.
Repeated ICD shocks
Appropriate shocks can be distressing and affect daily life. Ablation may reduce how often they occur.
VT storm or incessant VT
Repeated episodes within a short period are an emergency managed in hospital. Ablation may be considered urgently within a wider treatment plan.
VT from a single focus in a structurally normal heart
Some people with idiopathic VT may be offered ablation as a primary option, depending on symptoms and preference.
Whether ablation is suitable depends on the cause of the VT, the heart condition and the overall risk. It is decided individually by the treating team.
Planning
Preparation and Mapping
ECGs of the VT, device recordings and details of episodes.
Imaging
Echocardiography and, where relevant, cardiac MRI or CT to locate scar.
Treatment of the cause
Coronary disease, heart failure and medicines are optimised.
3D electroanatomical mapping defines the circuit or the scar-related substrate.
Complexity
Scar, Substrate and Procedure Complexity
In scar-related VT the circuit passes through channels of surviving tissue within scar. Voltage maps show where scar lies, and mapping can identify abnormal electrical signals inside it. When VT is not stable enough to be mapped, or cannot be triggered, substrate-based techniques treat these abnormal areas without needing the tachycardia to be running.
Because of this, these procedures are among the more complex catheter ablations. Imaging beforehand, detailed 3D mapping and, in selected patients, additional circulatory support or an arterial route may be used. The length and the risk depend on the type and extent of heart disease, and patients are closely monitored. See 3D Electroanatomical Mapping.
The Procedure
What Happens During VT Ablation
Catheters are placed through blood vessels, usually at the groin, and in some cases through the arterial system to reach the left ventricle. Sedation or general anaesthesia may be used, according to the complexity of the case and patient factors.
The team creates a 3D map, may induce the tachycardia under controlled conditions, and applies radiofrequency energy at the identified targets.
Procedures for scar-related VT can be long and are usually carried out in patients who are closely monitored. Duration varies widely.
When the origin lies on the outer surface of the heart, an epicardial approach may be considered; see Epicardial Ablation.
Expectations
Benefits, Limits and Risks
Potential benefits
Fewer VT episodes and, for some, fewer ICD shocks and improved wellbeing. A cure cannot be promised in structural heart disease.
Limits
New circuits may develop over time and further procedures may be needed. Medication and devices often continue.
Risks
Include vascular injury, bleeding, stroke, injury to the heart or valves and, in sicker patients, worsening of heart failure. Risks are higher in advanced disease and are discussed individually.
After Ablation
Recovery and Follow-Up
After the procedure patients are observed, and those with structural disease may be monitored more closely and for longer.
Follow-up includes rhythm and device checks and review of medicines. Instructions about activity and driving are tailored to the individual and the underlying heart condition.
See also After Your Procedure.
Devices and options
Ablation, the ICD and the Epicardial Option
Ablation aims to reduce VT episodes and ICD shocks. The ICD remains active as protection. After ablation, device recordings help show whether episodes have changed, and the team decides on device settings and medicines. See Implantable Cardioverter-Defibrillator and Ventricular Tachycardia.
When imaging or mapping suggests a circuit on the outer surface of the heart, or an inner-surface approach has not controlled VT, an epicardial approach may be considered. It adds specific risks and is chosen selectively. See Epicardial Ablation.
Medicines may continue alongside ablation. See Antiarrhythmic Medication.
Questions