Catheter ablation for ventricular tachycardia (VT) is a method of cardiology that can be used to eliminate this cardiac arrhythmia after an electrophysiological study (EPU). Catheter ablation (lat. ablatio “ablation, detachment”) of the tissue parts that send pathological (diseased) electrical impulses is performed using a catheter-based procedure by inducing a scar. The local destruction of the tissue (= scar) can interrupt the incorrect transmission of the electrical impulses. Ablation of the tissue is then performed at the EPU, in which electrical signals are registered at various points in the heart via the electrode catheters and any cardiac arrhythmia present is triggered by inducing pacemaker pulses. For ablation of the tissue, radiofrequency ablation (RF ablation) is the most commonly used method, in which the use of electricity heats the tissue in the heart, creating a scar that no longer has electrical activity. Catheter ablation of VT in structurally healthy hearts can now be considered a possible primary and curative form of therapy. VT belongs to the group of ventricular arrhythmias – which include ventricular flutter and ventricular fibrillation in addition to ventricular tachycardia. Ventricular tachycardias (VT) are the most common cause of wide-complex tachycardia (heart rate: > 120/min; QRS complex: duration: ≥ 120 ms). They are considered potentially life-threatening. Sustained ventricular tachycardia (VT) is when it lasts longer than 30 seconds or requires a more rapid interruption for hemodynamic reasons. In most cases, ventricular tachycardia (VT) occurs as a result of structural heart disease, such as coronary artery disease (CAD; coronary artery disease) or myocardial infarction (heart attack). Rarely, VT occurs in patients without heart disease. Prognosis depends on the underlying cardiac disease. Patients who have persistent (ongoing) ventricular tachycardia in the first three months after a myocardial infarction have the worst prognosis. In this case, lethality (mortality relative to the total number of people with the disease) is as high as 85% within the first year. If persistent ventricular tachycardia is detected after myocardial infarction, those affected have a threefold increased risk of lethality compared to similar patients without these arrhythmias. Patients without heart disease do not have an increased risk of lethality compared with the normal population. Note: Catheter ablation is also the most effective method for suppressing monomorphic ventricular extrasystoles (VES). For example, catheter ablation may be useful for >6-10% VES within 24 hours or >10,000 VES in 24 hours plus reduced left ventricular ejection fraction (LVEF; blood volume ejected from the left ventricle during a cardiac action).
Indications (areas of application)
- Ventricular arrhythmias (cardiac arrhythmias originating in the ventricles).
- Idiopathic ventricular tachycardia (VT; chamber-related tachycardia) – VT in which a structural anatomic cause has been ruled out can also be treated in part by catheter ablation:
- When a monomorphic VT causes pronounced symptoms.
- When antiarrhythmic drugs are not effective, not tolerated, or not desired
- Frequent ventricular extrasystoles (VES), nonsustained VT (nsVT from non-sustained), or VT thought to cause LV dysfunction
- Recurrent sustained polymorphic VT or ventricular fibrillation (VF) not suppressed by antiarrhythmic therapy when an underlying trigger can be addressed by ablation
- Structural ventricular tachycardia – myocardial infarction is considered the most common cause of structural ventricular tachycardia requiring ablation.
- Idiopathic ventricular tachycardia (VT; chamber-related tachycardia) – VT in which a structural anatomic cause has been ruled out can also be treated in part by catheter ablation:
Contraindications
Absolute contraindications
- Coagulation disorders – a coagulation disorder that has not been treated or is considered untreatable is an absolute contraindication to the procedure.
- Infections – in the presence of acute generalized infectious disease or infections of the heart in the form of endocarditis (endocarditis) or myocarditis (inflammation of the heart muscle) are also absolute contraindications.
- Allergy – in the case of an existing allergy to a drug that is used in the treatment, this is to be considered an absolute contraindication.
Relative contraindications
- Reduced general condition – if the risk for the procedure is too great due to reduced general condition, the procedure should not be performed.
Before therapy
Differentiation of various tachycardic arrhythmias is often very difficult in practice. However, an exact differentiation of the arrhythmias is mandatory, because the therapeutic measures sometimes differ fundamentally and an incorrect treatment can cause an aggravation of an existing disease.
- Anamnesis – during the anamnesis, the triggers of the arrhythmias, duration and first occurrence, symptoms, occurrence in the family, and the patient’s own measures to improve the symptoms, among other things, must be addressed. As a rule, no diagnosis can be derived from the history alone.
- Physical examination – the physical examination is composed primarily of auscultation of the heart and lungs, assessment of pulse qualities and blood pressure, and detection of possible signs of heart failure.
- Electrocardiogram – of critical importance in the detection of cardiac arrhythmias is electrocardiography using a 12-lead surface electrocardiogram. The number of channels has an important influence on the diagnostic reliability of the procedure. If the treating physician has sufficient experience, the ECG can be used to make the correct diagnosis in more than 90% of cases. Despite this high detection rate, it is inevitable to create a detailed “risk profile” in patients with arrhythmias from anamnestic, clinical and non-invasive examination findings and, if necessary, to expand this with invasive measures such as coronary angiography (radiological procedure that uses contrast agents to visualize the lumen (interior) of the coronary arteries (arteries that surround the heart in a wreath shape and supply the heart muscle with blood) if necessary.
- Cardio-computed tomography (synonyms: cardio-CT; CT-cardio, cardiac computed tomography (CT); coronary CT (CCTA)): radiological examination procedure in which computed tomography (CT) is used to visualize the heart and its supplying vessels; this image data is used, among other things, for three-dimensional electrical reconstruction during examination/treatment.
- Cardio magnetic resonance imaging (synonyms: cardiac magnetic resonance imaging (cMRI), cardio-MRI; cardio-MRI; MRI-cardio; MRI-cardio): this is used to specifically image the heart; method allows motion studies and anatomical sections of the heart.
- Electrophysiological examination (EPU) – this is a special cardiac catheter examination in patients with cardiac arrhythmias. The aim of this examination is to determine the nature and mechanism of the underlying cardiac arrhythmia, as well as to accurately locate the origin of tachycardia (mapping = map-like registration of cardiac action currents). Modern three-dimensional (3-D) mapping techniques offer the opportunity to significantly improve the results of catheter ablation by providing a spatial representation of the activation fronts. The procedure: Two to four electrophysiological cardiac catheters (approximately 2-3 mm in diameter) are inserted into the right heart via the inguinal veins under X-ray fluoroscopy. These electrode catheters are used to derive local electrocardiograms at various points in the heart and to trigger a cardiac arrhythmia with the aid of imperceptible pacemaker pulses. The cardiac arrhythmia triggered in this way can be terminated again via the inserted catheters with pacemaker pulses or by fast-acting drugs. Once the cardiac arrhythmia has been diagnosed, the therapy can be planned.As a result, a three-dimensional image of the right and/or left ventricle (heart chamber) is created as part of the 3-D mapping procedure and the electrical activation during the arrhythmia is recorded.Note: EPU is performed again after ablation has been performed to be sure that complete isolation of the pathogen site has occurred.
The procedure
The procedure is performed under analgesia. According to the above description of the electrophysiological examination, the electrophysiological cardiac catheters are advanced to the heart. After 3-D mapping findings are available, ablation therapy is performed. In ablation, different energy sources are the focus of clinical research in order to achieve optimal complete destruction of the tissue parts that send pathological (diseased) electrical impulses with as few individual applications as possible. Different methods include highly focused sonography, laser energy (laser ablation), radiofrequency current (radiofrequency ablation or radiofrequency ablation), and cryothermia (cryoablation). The majority of cardiac centers use radiofrequency ablation for ablation. After successful ablation, the patient usually waits for some time to see if the atrophy site recovers. Then, the catheters are removed again.
After therapy
After therapy, it is necessary for the patient to observe strict bed rest for 6 (-12) hours. Furthermore, it is useful to perform inpatient monitoring on the first postoperative day to detect possible complication earlier. Showering is generally possible 2 days after therapy. Lifting heavy loads should be avoided for the next 2-3 days. Sexual abstinence is required for one week.Physical rest is advised for the first 10 days after catheter ablation. Sports activities can be taken up after four weeks, as long as there are no other illnesses that would prevent this.In the further course, ECG control examinations are necessary in order to be able to check the lasting success of the therapy. Close follow-up care is initially considered advisable. Further notes
- In ICM (ischemic cardiomyopathy/coronary arteries) patients, efficacy rates (VT-free survival) of about 60% at 1 year seem realistic. Thus, catheter ablation can probably be recommended as a primary therapeutic strategy.
