Synonyms in the broadest sense
Sinus node syndrome, bradycardic arrhythmia, bradycardia–tachycardia syndrome.
Definition
The sinus node is not able to generate potentials in a sufficient frequency and/or pass them on to the AV node. Cause: In sinus node disease, either the function of the pacemaker cells is disturbed or the stimulation conduction system is blocked so that the electrical potentials cannot reach the AV node.
Symptoms
The symptoms are similar to those of 2nd and 3rd degree AV block. Click here for the symptoms: AV-Block
Causes
The sick sinus syndrome mainly affects elderly patients and is only in part due to organic heart disease. Often, the use of certain drugs that slow down the heartbeat is a potentially reversible cause. Such medications would be, for example, digitalis preparations, which are often used for heart failure (cardiac insufficiency), or antiarrhythmic drugs.
However, other substances may also be considered. A special form of sinus node syndrome is bradycardia–tachycardia syndrome. Synonym: Paroxymal supraventricular tachycardia.
At this point it is useful to also take a look at the main page on bradycardia: What is bradycardia? After the onset of tachycardia (abnormally fast pulse) there is an asystolic pause (no heartbeat) until the then bradycardic sinus rhythm (slow heartbeat) resumes. So it is actually a constant change between a too fast and a too slow rhythm. In the tachycardic phases: Palpitations, dyspnoea (shortness of breath), angina pectoris (anxiety of the heart) In the bradycardic (slow) phases: Dizziness, syncope (fainting fits) and Adam Stokes fits (see above)
Diagnosis
The long-term ECG is used for diagnosis. In addition to recording the reduced heart rate, it also serves to quantify the disorder, i.e. to estimate the extent of the arrhythmia. The diagnosis can also be made using the exercise ECG. It shows that the inability to achieve more than 70% of the age-related increase in heart rate during exercise on an ergometer is not possible.
