Final answer:
Bradycardia is an abnormal heart condition with a HR below 60 bpm, which can be significant if accompanied by symptoms. It can have inherent or external causes and treatment includes addressing the underlying cause, with a pacemaker for serious cases. Tachycardia involves a HR above 100 bpm, with treatments varying based on the underlying cause.
Step-by-step explanation:
Bradycardia is a condition characterized by a resting heart rate (HR) that drops below 60 beats per minute (bpm) in adults. Although it's not always clinically significant, symptoms such as weakness, fatigue, and dizziness could suggest that the heart isn't supplying enough oxygenated blood to the body. When a patient's HR is normal but they exhibit symptoms, this may be referred to as relative bradycardia. Most individuals remain asymptomatic if the HR stays above 50 bpm.
The condition can be caused by inherent factors such as abnormalities in the sinoatrial (SA) or atrioventricular (AV) nodes, or external factors like metabolic disorders, endocrine system pathologies, electrolyte imbalances, neurological issues, or drug use. In cases of serious bradycardia, a pacemaker might be necessary. Determining and treating the underlying cause is crucial, which may also involve supplemental oxygen.
By contrast, tachycardia is an abnormally high resting HR, defined as above 100 bpm. Factors like stress, certain diseases, and physiological conditions like pregnancy can elevate HR. Treatment for tachycardia varies depending on its cause and may range from medication to procedures like ablation or the introduction of implantable cardioverter defibrillators.