Cardiac resynchronization therapy - CRT for short - is a treatment method that can be used for severe heart failure.
Cardiac is the medical term for heart, synchronous means simultaneously. Normally, the right and left heart beat at the same time, which is the only way to ensure an orderly blood flow. If both ventricles are activated at different times or irregularly, heart failure occurs, which can cause severe discomfort and in extreme cases can even lead to cardiac arrest.
The most common cause of irregular excitation of the ventricles is an acute heart attack or the consequences of a heart attack. A heart attack damages not only the heart muscles, but also the conduction system. The latter is largely responsible for the regular and orderly activity of the heart, which always correlates closely with the current state of stress. For example, the heart has to beat faster and more strongly during physical exertion, it slows down during sleep and the volume of blood ejected from it is significantly lower. All of this is controlled and regulated by the conduction system.
Cardiac resynchronization attempts to get both ventricles to beat at the same time again using targeted electrical stimuli. This is achieved by supporting the heart's actions with a pacemaker. This can measure the right atrium's own impulse activity and excite the right and left ventricle simultaneously (at the same time). As a result of this simultaneous excitation and impulse delivery, both ventricles beat in unison again and heart function improves noticeably.
The probes of this type of pacemaker are located in three places:
- the right atrium as the pacemaker (= sinus node)
- the right and
- the left ventricle
As the probes are located in both ventricles and the right atrium, this type of pacemaker is also known as a "three-chamber pacemaker". Another term that is also often used is biventricular pacemaker, as both ventricles are excited (bi = two; ventricular = relating to the chamber). This is to be distinguished from a dual-chamber pacemaker, in which one probe is placed in the right atrium and the second in the right ventricle. However, resynchronization is not possible with this device.
Anatomy of the heart © designua / Fotolia
In heart failure, the two chambers of the heart no longer work in the same rhythm. This is particularly the case if there is a so-called left bundle branch block . This is a specific conduction disorder of the heart. The greater the imbalance in the rhythm of the ventricles, the worse the heart's performance. The consequence for patients is that they experience shortness of breath even with slight exertion. In addition, the unnatural strain further weakens the already impaired heart, which can become life-threatening. If the symptoms of severe heart failure do not improve significantly even with optimal treatment with medication, cardiac resynchronization therapy (CRT) may be an option.
In addition to these factors, there are other criteria for the use of CRT:
- there is dilated cardiomyopathy, i.e. a significant enlargement of the heart chambers
- the left ventricle is restricted in its performance
- certain changes in the ECG indicate a left bundle branch block, i.e. a disturbance of conduction in the left ventricle
Whether CRT is suitable for you must be decided on a case-by-case basis by the doctors treating you.
In order to insert the three-chamber pacemaker, an operation is necessary, which should preferably take place in a specialized cardiology clinic. This type of pacemaker ensures that the individual parts of the heart work in unison again. Sometimes a general anesthetic is necessary, but in most cases the operation can and should be performed under local anesthesia. The patient is given a sleep-inducing drug.
As with other pacemakers, one electrode is placed in the right ventricle and one in the right atrium of the heart. To do this, fine wires are pushed forward in a vein and then fixed in the right place. With CRT, a third electrode is then attached to the left ventricle. A combination with an implantable defibrillator is also possible. This can be particularly life-saving if the heart develops dangerous arrhythmias, e.g. ventricular fibrillation.
The pacemaker itself is placed near and slightly below the collarbone, where it is inserted under the skin, which is then sutured shut after a function test. The operation often takes about 30 to 60 minutes. In rare exceptional cases, e.g. if the probes are difficult to place, it may take longer. Depending on the clinic, the procedure is planned as an outpatient or short inpatient procedure. Most patients can leave the hospital after three days at the latest.
You will be given precise instructions on how to use your CRT device at the clinic. During the first few days, you must observe the surgical wound and have the wound checked if there are any abnormalities (e.g. fever, redness or chest pain). Redness and swelling may be due to a harmless allergic reaction to the suture material, but may also be caused by a wound healing disorder or even a deep-seated infection in the pacemaker pocket. In the latter case, it may even be necessary to open the wound surgically.
Fortunately, however, this complication is very rare. Nevertheless, a wound check is always necessary after around 10 to 14 days, when the suture material is removed if the wound conditions are normal. In some cases, the wound is also sutured intracutaneously, which means that the suture material lies under the skin, is not visible from the outside and dissolves itself. As soon as the wound has healed, you will be able to bear some weight again. You should only rest the arm on the side of the operation for around 4 to 6 weeks.
Make sure that you do not overexert yourself at first, but only slowly resume weight-bearing. In order to program the CRT device exactly to your needs, you will usually need to stay in hospital again. Your heart rate and heart rhythm will be closely monitored before the pacemaker receives its final programming. The pacemaker can now begin its work and compensate for irregularities with targeted electrical impulses.
At regular follow-up appointments, the doctor checks whether there is still enough energy in the pacemaker battery. This check can be carried out externally by placing a programming head on the skin. How long the battery lasts depends on the individual settings, which are also made using the programming head. If the energy in the battery decreases too much, it must be replaced. This is done by means of a minor operation. The skin pocket with the CRT device is opened and the device is replaced with a new one. The electrodes on the heart can usually remain in place during this procedure so that the operation can be carried out quickly.
Once cardiac resynchronization therapy has been started, you will receive a pacemaker card. This contains all the information about the pacemaker that may be important for other medical treatments. Always carry the pacemaker card with you and inform other medical professionals about your CRT device before starting treatment.
The first follow-up with the exact programming takes place directly after implantation. After about three months, the settings should be checked again and adjusted if necessary. If everything is in order, check-ups every six months are sufficient, under certain circumstances even every twelve months. The intervals between follow-up appointments must be shortened if
- the replacement date is expected soon
- certain special functions need to be adjusted or
- the measured values are unstable
In most cases, patients tolerate cardiac resynchronization therapy well and the operation runs smoothly. However, a small number of patients may experience complications, for example infections in the wound area or injuries to blood vessels or even the heart wall. Some patients find the CRT device under the skin uncomfortable even during the recovery period. Often, reassuring words from the treating doctors that the device is inconspicuous and has healed well are sufficient. In the past, pacemaker units were much larger than today's modern devices. They are very flat and sometimes only the size of a €2 coin. If you still develop symptoms, it is highly recommended that you have a medical check-up, preferably by the surgeon who performed the operation.
The CRT device increases the blood flow and the performance of the heart. This significantly improves the symptoms of heart failure in most patients. Physical resilience increases, shortness of breath, dizziness and excessive tiredness decrease. As a result, many patients regain a completely new quality of life . At the same time, the risk of hospitalization and life-threatening emergencies is significantly reduced. In many cases, CRT improves both the lifespan and the quality of life of patients.
