Cardiac arrhythmia
Description
Cardiac arrhythmia is defined as a heart rhythm that differs from the normal sinus rhythm. Those affected experience this as palpitations (extrasystole), a racing heart (tachycardia), dizziness, loss of consciousness or cardiac insufficiency. The doctor can detect whether arrhythmia is present based on the electrocardiogram results. If the cause of the complaints is a heart rhythm that is too rapid, this is called tachycardia. A heartbeat that is too slow is called bradycardia.
The most common persistent form of cardiac arrhythmia is atrial fibrillation. This is tachycardia in which the pulse is generally too rapid and arrhythmic.
Symptoms
Possible symptoms of cardiac arrhythmia include: palpitations, rapid heartbeat, dizziness, drowsiness, confusion, fainting, brief loss of consciousness, seizures, chest pain and angina.
Rare but dreaded complications of cardiac arrhythmia may be: embolism (vascular occlusion by loose blood clots), stroke (cerebral infarction, apoplexy), heart attack (myocardial infarction), congestive heart failure, sudden cardiac death.
Causes and Risks
External causes of cardiac arrhythmia include: nervousness, agitation and anxiety, excessive consumption of caffeine (e.g. coffee or cola), excessive alcohol consumption, use of drugs and toxins, side effects of some drugs (e.g. thyroid hormones or antidepressants) , febrile infections, irritation of the carotid sinus nodes (carotid sinus syndrome).
Organic causes of cardiac arrhythmia include: coronary artery disease (CAD), heart attack, heart muscle disease (cardiomyopathy), heart muscle inflammation (myocarditis), heart disease or valvular heart disease, congenital or acquired cardiac excitation disorders (e.g. Wolff-Parkinson-White or WPW syndrome), high blood pressure (hypertension), electrolyte disturbances (e.g. potassium deficiency), hyper- or hypothyroidism.
Examples of tachycardic arrhythmia include atrial fibrillation and atrial flutter: fast, irregular impulses in the atrium that lead to irregular heartbeat. Extrasystole: extra heartbeats that can emanate from either the atrium (supraventricular arrhythmia) or from the ventricle (premature ventricular contraction). Supraventricular tachycardia: rapid heartbeat that begins with impulses in the atrium. WPW syndrome: congenital additional conduction between the atrium and ventricle, which can lead to a racing heart (tachycardia). Ventricular tachycardia: tachycardia due to additional impulses in the ventricle. Ventricular tachycardia is serious because it can transition to life-threatening ventricular flutter or fibrillation. Ventricular fibrillation, ventricular flutter: rapid electrical impulses and contractions in the heart chamber. The problem is that the pumping performance of the heart rapidly declines, producing a functional cardiac arrest. Without immediate treatment, ventricular fibrillation will be deadly within a few minutes.
Examples of bradycardic arrhythmia include: AV (atrioventricular) block: delayed or blocked excitation transmission between atrium and ventricle of varying (I, II, III) degree leads to a slowed heart rate (bradycardia). If the transmission is completely blocked this can lead to cardiac arrest. In most cases a pacemaker implant is necessary. SA (sinoatrial) block: delayed or blocked excitation transmission between the sinoatrial node and atrium. Sick sinus syndrome: slowed heartbeat, sometimes also alternating tachycardia and bradycardia due to impaired function of the sinus node.
Examination and Diagnosis
Non-invasive diagnostics include: Electrocardiogram (ECG), stress ECG (ergometry), Holter (long-term) ECG, ECG mapping, cardiac event recorder, echocardiography, magnetic resonance imaging (MRI).
Invasive diagnosis is performed via electrophysiological examination (EPU) with catheter ablation preparation.
Treatment
Medicines that control heart rhythm are called antiarrhythmics. There are a variety of active agents and active agent groups. The classic antiarrhythmics include sodium channel blockers, beta receptor blockers, potassium channel blockers and calcium antagonists. They act on the conduction system of the heart and thus affect the heart rhythm. Medicines that control heart rhythm in the broader sense include cardiac glycosides (e.g. digoxin and digitoxin) which are primarily used in atrial fibrillation and atrial flutter with rapid conduction to the ventricles. Cardioversion is the restoration of normal sinus rhythm, which can be achieved with medications or using a defibrillator. Synchronized electrical cardioversion is used as emergency treatment of ventricular flutter, ventricular fibrillation and (supra-) ventricular tachycardia.
Another option for treatment of tachycardia is catheter ablation. This is useful if heart rhythm medications are unsuccessful. This is the targeted removal of heart muscle tissue in the atrium or ventricle, which was determined to be the origin of cardiac arrhythmia. This treatment is carried out via a cardiac catheter and can used with all forms of tachycardia (atrial fibrillation, atrial flutter, atrio-ventricular nodal re-entrant tachycardia, WPW syndrome, ventricular tachycardia).
If cardiac arrest threatens, the implantation of a pacemaker or defibrillator (electric shock device) may be the only alternative. A pacemaker is a small, battery-operated device that sends electrical impulses to the heart and thus normalizes the heart rhythm. In a minor surgical procedure it is implanted under the clavicle in the vicinity of the heart. An implantable cardioverter defibrillator (ICD) is particularly suitable for individuals with a high risk of ventricular fibrillation. In a cardiac emergency it generates an electrical surge which restores regular heart action.
Course and Prognosis
Not every cardiac arrhythmia requires treatment, and if external causes are responsible for its emergence, these should of course be eliminated first. An especially urgent priority is the treatment of diseases that contribute to the development of cardiac arrhythmia, such as high blood pressure, coronary heart disease or thyroid dysfunction.