What is ablation?
In cardiac ablation, heat or cold, and rarely ultrasound or laser, are used to cause targeted scarring in those cells of the heart muscle that generate or conduct electrical excitation incorrectly. In this way, muscle excitations that disturb the normal heart rhythm can be suppressed – the heart beats normally again.
This procedure is almost always performed with the help of a catheter, which is advanced to the heart through a blood vessel in the groin. The procedure is therefore also called “catheter ablation”. An electrophysiological study (EPU) usually precedes cardiac ablation. Sometimes doctors combine cardiac ablation with a necessary surgery (then called surgical ablation).
Cardiac arrhythmias
The conduction system in the heart determines the heart rhythm. The main impulse comes from the sinus node, which is located in the wall of the right atrium. From there, the electrical excitation travels via the atria, then – as a switching point between the atria and the ventricles – via the AV node and the His bundle into the ventricular legs (Tawara legs) and finally into the Purkinje fibers. They excite the heart muscle from the apex, triggering its contraction.
If the flow of electrical signals is misdirected or additional impulses are generated in the heart wall, the heart rhythm is disturbed. The heart muscle then works in an uncoordinated manner and the blood is pumped into the bloodstream less effectively or – in the worst case – not at all.
When is a cardiac ablation performed?
Atrial fibrillation
In atrial fibrillation, the atrium is irregularly excited by circular or disordered impulses. Some of the impulses are transmitted to the ventricles, which therefore contract irregularly and often too rapidly (tachyarrhythmia).
This is manifested by symptoms such as a drop in performance, rapid heartbeat, dizziness, shortness of breath, chest pain or feelings of anxiety. In addition, the disturbed blood circulation can cause blood clots to form, especially in the atrium of the heart, which – if they break loose – can trigger a stroke, for example.
The success of cardiac ablation for atrial fibrillation varies depending on the type (seizure-like or persistent) and extent of the disease. In addition, how precisely the treatment is performed plays a role. The physician can sclerotize the tissue in a circular, segmental, punctiform or linear fashion.
Atrial Flutter
Atrial flutter is essentially the same as atrial fibrillation. One difference, however, is that the atrium contracts at frequencies above 250 to 450 beats per minute, whereas in atrial fibrillation it can be 350 to 600 beats. In addition, atrial flutter is regular.
In most cases, the so-called inferior isthmus triggers atrial flutter. This is a section of muscle in the right atrium located between the confluent inferior vena cava and the tricuspid valve. In these cases, ablation is the treatment of choice with a success rate of over 90 percent.
Atrial tachycardia (atrial tachycardia)
Wolff-Parkinson-White syndrome (WPW syndrome).
WPW syndrome is one of the AV reentrant tachycardias (AVRT). In addition to the normal conduction pathway between the atrium and ventricle, this disorder has an additional (accessory) conduction pathway that is a “short circuit” to the myocardium.
This results – usually in attacks – in the impulses reaching the ventricles more quickly and the ventricles then contracting more rapidly (heart rate about 150-220 beats per minute). Cardiac ablation is particularly useful when these arrhythmias occur frequently. The success rate is high (over 95 percent).
AV Nodal Reentry Tachycardia
In AVNRT, electrical impulses circle in the AV node (this has two leads here). This causes sudden heart palpitations that can last minutes to hours, leading to dizziness and fainting. In an EPU, the doctor looks for the slower of the two conduction pathways and obliterates it.
What do you do during a cardiac ablation?
Cardiac ablation is a minimally invasive procedure. This means that the therapy causes only the smallest injuries to the skin and soft tissues. As with any surgery, a few standard examinations are performed beforehand, such as an ECG and a blood sample. In addition, there is a detailed personal consultation and explanation by the attending physician.
Before the actual ablation, an electrophysiological examination (EPU) is performed. This helps the specialist to precisely determine the cardiac arrhythmia and the point of origin.
After a local anesthetic, the physician usually punctures a vein in the groin and places a so-called “lock” there. Like a valve, this prevents blood from escaping from the vessel and at the same time allows the catheter or other instruments to be inserted into the bloodstream.
X-rays and an evaluation of the electrical signals from the catheters are used to determine their location. Now the electrical signals that trigger the cardiac arrhythmia can be registered at various points in the heart. Under certain circumstances, the physician may also apply electrical impulses, for example, in order to trace the origin of a seizure-like cardiac arrhythmia.
For ablation of the heart, the physician now inserts an ablation catheter to obliterate the sites of origin of the interfering signals or faulty leads. Radiofrequency ablation uses a type of high-frequency current.
To monitor success, an attempt is made to stimulate a specific cardiac arrhythmia. If no disturbance occurs, the ablation can be terminated. The catheters are removed and the venous puncture site is closed with a pressure bandage.
Following the ablation of the heart, the cardiac activity is still documented by ECG, blood pressure measurements and an ultrasound examination. After about one to two days, the patient can leave the hospital.
What are the risks of cardiac ablation?
In addition to the general risks of any procedure, such as bleeding and infection, specific complications can occur during cardiac ablation. These are rare, however, because catheter ablation is a fundamentally gentle procedure.
- Pericardial effusion (pericardial effusion to pericardial tamponade) – in this case, a tear in the muscle causes bleeding into the space between the heart and the pericardium
- Destruction of the excitation conduction system – this must then be treated with a pacemaker
- Blood clot formation (thrombosis)
- Constriction/occlusion of the pulmonary veins
- Injury to surrounding structures and organs
- Hemorrhage or post-operative bleeding at the puncture site
- Vascular occlusion
One to two weeks after ablation, you should avoid heavy physical exertion and sports to prevent postoperative bleeding. You should not push hard when having a bowel movement. The medication for arrhythmia treatment that was necessary before the operation is usually taken for another three months. In addition, therapy to inhibit blood clotting is necessary for at least eight to twelve weeks, as otherwise blood clots could form in the scarring areas.
Intensive monitoring with resting ECGs, long-term ECGs and ultrasound examinations enable the physician to reliably detect possible complications and the success of the ablation. If arrhythmias recur, further ablation of the heart may be advisable.
