Information on catheter ablation

Nowadays, almost all tachycardic arrhythmias can be treated sensibly and curatively with catheter ablation. For many tachycardias, it is even the therapy of choice and is superior to drug therapy. This applies, for example, to WPW syndrome, AV nodal re-entry tachycardia and typical atrial flutter. But catheter ablation is also indicated for atrial fibrillation and ventricular tachycardia, especially in symptomatic patients, also because drug therapy strategies are usually not successful in the long term. Catheter ablation is already performed in our centre in children from a body weight of about 20 kg with a very high success rate and low complication rate.

How is an ablation performed?

Ablation using high-frequency alternating current, known as radiofrequency current (RF), is the oldest and most versatile procedure. RF current is delivered via the catheter tip. As the current passes through the cells, they become heated, the tissue denatures and liquefactive necrosis occurs. The size of the lesion corresponds to approximately four to twelve millimetres in diameter, depending on the energy and contact pressure used, although the depth extension can vary considerably from two to 14 millimetres.

Important for safety: flushed catheters

To avoid overheating of the catheter tip when using higher energy, irrigated tip catheters are available, in which the catheter tip is cooled during current delivery by 0.9% NaCl solution pumped through small holes in the electrode.
Such catheters are mainly used when thrombus formation on the catheter tip must be avoided at all costs (ablations in the left heart) or when high-energy RF deliveries are required (ventricular ablation targets). In recent years, laser energy, microwaves and ultrasound have also been used as alternative forms of energy to radiofrequency current, while cryotherapy, ablation via extreme cold, has become the most widespread. For cases where a particularly gentle ablation is necessary, e.g. para-Hisian WPW syndrome, we have this cryo procedure available at the German Heart Centre.

Less radiation exposure: three-dimensional mapping systems improve the chances of success

At the German Heart Centre, the latest versions of 3D mapping systems (Carto3Uniview , NavX Precision and Rhythmia) are available in all three catheter labs used for electrophysiology. They are mainly used for all complex arrhythmias: with them, a detailed 3D reconstruction of the cardiac chamber to be examined can be made in a few minutes, including the representation of the electrical excitation processes; in the further course, the intracardially positioned catheters can be displayed and manoeuvred in these systems in real time. This has dramatically reduced X-ray fluoroscopy times for ablation of atrial fibrillation, for example. Perhaps more importantly, the chances of success of ablation, especially for ventricular tachycardia and atrial fibrillation, have been significantly improved. The creation of a long ablation line is thus much more effective and seamless with these systems, and the “return” to a previously visited site can also be carried out precisely to the millimetre.

Magnetic catheter navigation: high-tech for congenital defects

With magnetic catheter navigation (also called stereotaxy or remote navigation), we have the possibility of controlling a special, very soft ablation catheter in the heart from the outside by means of magnetic force using two very large standing magnets. The two magnets are placed close to the patient at heart level and the magnetic field vector can be controlled from outside using a computer system. The catheter tip always aligns itself parallel to the magnetic field vector and is thus pulled towards the heart wall. This system offers immense advantages, especially in complex congenital heart defects with difficult access to the respective heart cavities, as the catheter tip can still be easily controlled even after many “turns”. We have used magnetic navigation at the German Heart Centre Munich for patients with complex congenitalCongenital. defects and were thus able to significantly improve the success of catheter ablation and at the same time considerably reduce fluoroscopy times.