Treatment of cardiac dysrhythmia

When the heart loses its rhythm

A healthy heart beats approx. 60 to 80 times a minute, which adds up to about 100,000 beats a day. In doing so, occasionally the heart may lose its rhythm. Many cardiac dysrhythmias are harmless but other types might assume life-threatening proportions or cause considerable discomfort. For this reason it is advisable to have a cardiac dysrhythmia and any underlying heart disease medically examined as a matter of principle.

Typical symptoms for cardiac dysrhythmia are heart palpitation, tachycardia or irregular heart rhythm. In addition to these symptoms, it is possible that the patient suffers from vertigo, vitality deficiency, fear and nervousness, short fainting fits (syncopes), temporarily impaired vision or disorder of articulation as well as cardialgia.

Cardiac dysrhythmia in need of treatment is mostly caused by a defective electrical impulse formation and impulse conduction of the heart. Electrical impulses provide for the atria and ventricles of the heart to beat in a concerted rhythm. For this purpose the heart has in its right atrium a small natural "pacemaker", the sino-atrial node. It spontaneously produces electrical impulses which disperse over the atria and stimulate the myocardial tissue to contract.

The atria are electrically insulated from the ventricles, so that they do not contract simultaneously but shortly one after the other - first the atria and then the ventricles. This sequence is controlled by the AV node (short for atrioventricular, between atrium and ventricle). It is this node only which ensures that the electrical signal from the heart's atrium will properly reach the ventricle. From the AV node the electrical excitation is distributed via a fine impulse-conducting system (HIS-Purkinje system) into the two ventricles.

Subsequently the myocardial cells will contract and the heart will pump. Outside the body it is possible to display this complex sequence of impulse formation and conduction by means of an ECG

Das Reizbildungs- und Reizleitungssystem des Herzens

The impulse-forming and impulse-conducting system of the heart


Various heart diseases can cause a disturbance of the impulse-forming and impulse-conducting system and consequently a cardiac dysrhythmia:

  • coronary heart disease
  • heart attack
  • cardiac insufficiency
  • myocarditis
  • valvular diseases
  • congenital or age-related defects or overexcitability of parts of the mpulse-forming and impulse-conducting system

In principle, we distinguish between various types of cardiac dysrhythmia:

  • tachycardia (too fast heart rate, > 100 beats/min.)
  • bradycardia (too slow heart rate, < 60 beats/min.)
  • extrasystoles (individual extra heartbeats) which cause arrhythmia in the form of irregular heartbeat and/or missing or excessive beating of the heart

Depending on the location of the fault in the impulse-forming and impulse-conducting system the result is a variety of manifestations of cardiac dysrhythmia:

  • inadequate function of the sino-atrial node
  • atrioventricular (AV) block
  • atrial flutter or atrial fibrillation
  • ventricular or supraventricular extrasystoles
  • ventricular or supraventricular tachycardia
  • ventricular flutter and ventricular fibrillation

Some cardiac dysrhythmias, for instance the ventricular flutter, ventricular fibrillation or occasionally also a severe AV block are life-threatening as they are accompanied by a cardiocirculatory arrest. The output performance of the heart is reduced to zero and the body is no longer supplied with blood. In such cases it is necessary that those present - albeit laypersons - immediately provide resuscitative measures and call an emergency physician.


We can help the heart to regain its rhythm

The therapy of a cardiac dysrhythmia essentially depends on the underlying cause. If there is a basic disease (e g. high blood pressure, disturbed thyroid function) resulting in cardiac dysrhythmia, it will be necessary to first of all treat this basic disease in an optimized fashion.

For a targeted medication of acute or chronic cardiac dysrhythmias a variety of different drugs is available. Some types of cardiac dysrhythmia (e.g. atrial fibrillation) require the patient to additionally take specific anticoagulants (such as, e.g., Marcumar®) to prevent the formation of blood clots. Such blood clots might lead to embolism and clog the vessels of other organs thus, for instance, triggering a stroke.

As an emergency therapy for certain life-threatening cardiac dysrhythmias we use defibrillation and cardioversion. Via two contacts held onto the chest of the patient a strong electrical impulse is given, which, e.g. in a case of ventricular fibrillation, "equalizes" all myocardial cells (defibrillation) and thus enables the heart to restore its coordinated beat. An electrical impulse synchronized with the electrical heart cycle (cardioversion) can be required for cardiac dysrhythmias, e.g. in case of atrial fibrillation. Defibrillation and cardioversion are painful procedures and are therefore performed only while the patient is unconscious or under short anaesthesia.

Where a drug therapy is insufficient regarding the treatment of cardiac dysrhythmia, one can choose between other proven and safe treatment alternatives:

  • catheter ablation
  • implantation of a pacemaker
  • implantation of a cardioverter-defibrillator (ICD)

The trigger of the cardiac dysrhythmia can be switched off specifically by a well directed intervention

During cardiac catheter ablation a specific catheter is used to intervene at that point of the heart where the cardiac arrhythmia is triggered or maintained. This technique is applied for many different cardiac dysrhythmias that severely stress or threaten the patient and where medication is insufficient

An electrophysiological examination (EPE) serves to precisely locate the affected point in the heart. After a local anaesthesia has been applied in both groins the physician introduces a plastic sluice into the respective veins. Subsequently, the electrode catheters required for the intervention are advanced under X-ray control to the right heart. Then - according to the subject of examination - we provoke a programmed excitation of the tissue in order to trigger and analyze the cardiac dysrhythmia. Precisely at the location of the cardiac dysrhythmia the physician places the ablation catheter and obliterates the area causing the arrhythmia by means of high-frequency current which will increase the temperature prevailing in the tissue

After the ablation the physician will try once more to trigger the cardiac dysrhythmia, possibly by administering medication or by stimulating the musculature via electrical impulses, to make sure that the intervention was successful.

A pacemaker can replace the diseased impulse-forming and impulse-conducting system

For certain types of cardiac dysrhythmia it is possible to replace the defective impulse-forming system and/or to bridge the impulse-conducting system by implantation of a pacemaker. In principle, a pacemaker assembly consists of at least two parts, a pacemaker box with battery and a pacemaker probe.


Herzschrittmacher mit zwei Herzschrittmachersonden

Pacemaker with two pacemaker probes

The so-called pacemaker box contains the entire electronics of the pacemaker and the lithium battery which will last for 6 to 10 years, depending on utilization. Nowadays, a common pacemaker box is merely the size of a matchbox. During a comparably small surgical intervention under local anaesthesia the pacemaker box is implanted under the skinin a subclavian position. The pacemaker probe that is required for the stimulation of the heart is advanced into the heart after a vein has been exposed and punctured, the whole procedure being monitored by radioscopy. The pacemaker probe is provided with a small hook or a tiny screw at its tip allowing the probe to be fixed in the heart at a precisely specified point.

There are various types of pacemakers for the different cardiac dysrhythmias

A single-chamber pacemaker serves to stimulate either the right atrium or the right ventricle only. This type of pacemaker requires just one pacemaker probe. Whenever the heart fails to actively stimulate its beating, the pacemaker will send electrical impulses into the heart and induce the atrium or the ventricle to contract.

The dual-chamber pacemaker can stimulate the right atrium and the right ventricle, but in exceptional cases also the left ventricle, and usually requires two pacemaker probes. Dual-chamber pacemakers control the atrium and ventricle in a concerted action.

Specific so-called three-chamber pacemakers for cardiac resynchronization therapy (CRT) have a minimum of three pacemaker probes which facilitate stimulating the right atrium as well as the left and right ventricle. These systems are used for the treatment of cardiac insufficiency, when the heart fails to beat synchronously, i.e. in a concerted action. For more details on this subject please see Treatment of cardiac insufficiency.

Today, pacemakers are equipped with specific sensors which automatically adjust the heart rate to the living conditions of the patient. Accordingly, the heart rate will accelerate when the pacemaker wearer, for example, is doing physical exercises as it correspondingly adapts to the individual needs of the person.

An implantable cardioverter-defibrillator (ICD) can prevent sudden cardiac death

If a cardiac dysrhythmia, e.g. with ventricular tachycardia or ventricular fibrillation, is threatening a person's life, an ICD can normally save the patient. The defibrillator controls the heart's activity via the implanted ventricular electrode. As soon as the ICD perceives a dangerous cardiac dysrhythmia, it can emit painless current pulses to stop the tachycardia. If there is a heart arrest following ventricular fibrillation, the ICD will defibrillate automatically. Thus, an ICD protects the patient wearing it effectively against sudden cardiac death.

An ICD consists - just like a common pacemaker - of a box and probes. The box of an ICD, however, is somewhat larger than that of a standard pacemaker since it requires more battery capacity. The lithium battery of an ICD will last for 4 to 8 years, depending on utilization. From a technical point of view, the implantation is comparable to an implantation of a standard pacemaker. The intervention is usually performed under short anaesthesia because after successful implantation the ICD must be tested for functional capability and for this purpose it is necessary to actively trigger a ventricular fibrillation in the patient.


Safety thanks to the most advanced medical equipment

The implantation of a pacemaker is mostly performed under local anaesthesia and when the patient is awake. An ICD is principally implanted under short anaesthesia owing to the testing described above. Before the intervention is commenced, the patient must be covered with a large sterile drape for hygienic reasons. During the intervention the patient is monitored by means of the most advanced circulatory and respiratory monitoring equipment. According to the type of pacemaker to be implanted and the required number of probes the implantation in the Schüchtermann-Klinik will take between 25 and 40 minutes.

Catheter ablation and implantation of a pacemaker: safe and successful

The catheter ablation is classified as a particularly neat and successful treatment approach, as - depending on the present cardiac dysrhythmia - many patients can be discharged as cured or improved. The ablation technique has been considerably refined in the past years and the risk of that intervention is very low. After successful ablation most of the patients can do without any further medication in this respect; many patients are deemed to be cured.

In Germany over 20,000 pacemakers and approx. 6,000 ICDs are implanted every year. Such interventions bear a very low risk as well. The therapeutical success is remarkably higher than with a therapy based on medication. Today's pacemakers are technically so mature that their function can be adapted to the individual patient's needs most precisely. After a short time many pacemaker wearers feel the same as before receiving their pacemaker and can lead a perfectly normal everyday life. They mostly don't even notice that their heart is artificially being maintained in its normal rhythm.

Nevertheless, for a pacemaker patient it is important to observe some safety instructions. The pacemaker identification card should be available at all times and showed to any security staff, e.g. when travelling by plane. Monitored entrance locks and handheld metal detectors disturb the pacemaker performance. Even the electric ignition of an engine will possibly lead to a disturbed functioning of the pacemaker, if the pacemaker wearer leans over the open hood of a running car.

Warnung für Herzschrittmacherträger

Warning sign for pacemaker wearers

Moreover, pacemaker patients should keep off the following potentially electromagnetical sources of interference, in the vicinity of which the respective warning signs are often affixed:

  • electric arc and resistance welding equipment
  • induction furnaces or electrical heating systems
  • electrical furnaces for steel production
  • large generators
  • broadcasting stations

Pacemaker wearers must never be examinedin a magnetic resonance tomograph (MRT) or come near it. The strong magnetical field of the MRT might cause a life-threatening situation for the pacemaker wearer.

The Schüchtermann-Klinik offers to pacemaker patients an outpatient checkup of the pacemaker and its functional performance. In the pacemaker outpatient department we keep several pacemaker information brochures available for our patients. For more details on this subject please see Cardiological outpatient department.

 

 
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