Systemic diseases:
Sinus bradycardia can be caused by influenza, typhoid, hypothyroidism, the convalescence of diphtheria, obstructive jaundice, increased intracranial pressure, some infections (leptospirosis and infectious mononucleosis), hypopituitarism, hyperkalemia, alkalosis, esophageal diverticulum, and depression.
Drug-induced diseases:
Sinus bradycardia can be induced by some drugs, including the beta-blocker, reserpine, lidocaine, amiodarone, guanethidine, morphine, digitalis, quinidine, verapamil, neostigmine, and anesthetic agents.
Cardiovascular diseases:
Bradycardia can also be triggered by acute myocardial infarction, myocarditis, endocarditis, sinoatrial node invaded by pericarditis, chronic ischemic cardiac disease, sinoatrial node inflammation, as well as the thrombosis, dilation, and inflammation of sinoatrial node arteries.
Bradycardia can induce many symptoms or severe consequences in multiple body organs, like ischemia, hypoxia, dizziness, fatigue, palpitation, chest tightness, shortness of breath, vertigo, amaurosis, syncope, and even death in severe cases.
Adverse effects on cardiac functions: patients with long-term bradycardia can easily suffer insufficient blood pumped by the heart, ultimately causing myocardial ischemia.
Frequent accidental injuries: patients with bradycardia are more likely to fall and hurt themselves or cause fractures and other injuries in physical exercise.
More brain damage: bradycardia often poses ischemia to patients, especially on the brain. Many patients with bradycardia will suffer from the diseases of brain hypoxia and damage.
Threats of renal failure: bradycardia will adversely affect patients' endocrine environment and even their metabolism of toxins. Some patients may be attacked by renal failure.
Patients suffering from sinus bradycardia without symptoms are not necessary to be treated if their heart rates are not less than 50 beats per minute.
For patients with symptoms and heart rates below 50 beats, heartbeat-enhancing drugs (such as atropine or isoproterenol) or pacemakers can be applied.
Patients should be implanted with artificial pacemakers if they appear noticeable symptoms of bradycardia and can confirm that the clinical symptoms are caused by sinus bradycardia, sinus arrest, atrioventricular block, or chronotropic incompetence.
Bradycardia is an important sub-type of arrhythmia. A healthy adult's heart rate ranges from 60 to 100 beats per minute. The one with a heart rate lower than 60 beats per minute suffers from bradycardia. Types of bradycardia include sick sinus syndrome, atrioventricular block, and bundle branch block.
