What Is Bradycardia?
A heart rate that is too slow is called bradycardia. In some cases, it may seem like the heart is skipping a beat from time to time. The heart rhythm of well-trained athletes may be very slow without any underlying health problem as their hearts are more efficient than the hearts of non-athletes. They are able to pump the same amount of blood into the body with fewer heartbeats. If the heart rate fails to supply the body with the needed blood and oxygen, bradycardia can be a severe health issue. In some types of bradycardia, the blood supply is sufficient at rest, but the heart rate isn´t able to adapt to situations of physical or emotional stress. This failure to adapt the heart rate is known as chronotropic incompetence.
Diseases, injuries or scar/cicatricle tissue may damage the heart’s natural pacemaker, the sinus node , causing the heartbeat to slowdown. This disorder of the impulse generating system is called sick-sinus-syndrome. In sick-sinus syndrome, bradycardia (a heart beat which is too slow) and tachycardia (heart beat which is too fast) may alternate, especially in the atria, or upper chambers of the heart.
If the heart rate doesn´t accelerate in stressful situations due to chronotropic incompetence, this is also usually a consequence of a damaged sinus node. Another potential cause of bradycardia is a disorder of the impulse conduction system, e.g., so-called heart block or atrioventricular block . In an atrioventricular block the impulse conduction between atrium and ventricle is delayed or blocked, resulting in a heartbeat which too slow. Risk factors for bradycardia increase with age and coronary artery disease progression.
Patients with chronic bradycardia complain of decreasing strength and endurance, poor concentration, temporary disorientation and dizziness. Dizziness, the feeling of being near a blackout and even fainting (syncope) may occur suddenly.
The physician makes a diagnosis on the basis of the patient´s symptoms, the findings of a physical exam and the results of an electrocardiogram (ECG or EKG). The ECG measures the heart’s activity and is used to diagnose episodes of bradycardia. In case of doubt or if the safety of the patient requires it, long-term monitoring of the heart’s activity may be indicated. If the findings of a long-term ECG (Holter monitoring) aren´t sufficient, the implant of a subcutaneous cardiac monitor may be useful to monitor the heart over a longer period of time. The procedure to implant this small device is ambulatory, very short and enables continuous remote monitoring of the heart’s activity. The physician is able to detect whether the patient suffers from an arrhythmia and to identify causes for as yet undiagnosable fainting (syncope).
Click here to learn more about therapy options for bradycardia .