Final answer:
It is generally true that tachycardia rates below 150 bpm do not usually cause serious symptoms, but this can vary depending on individual health and underlying causes.
Step-by-step explanation:
The statement that tachycardia rates less than 150 per minute usually do not cause serious signs or symptoms is largely true, but with some important considerations. Tachycardia is defined as a heart rate (HR) above 100 beats per minute (bpm), and while it is not normal in a resting patient.
It can be relatively harmless in certain situations such as in pregnancy or during stress when it may occur due to limbic system stimulation or autonomic nervous system disorders. However, symptoms like dizziness, shortness of breath, or fainting can occur depending on the underlying causes and the individual's health condition.
Common causes of tachycardia include fever, anemia, hypoxia, hyperthyroidism, and certain heart-related issues. It is critical to determine the cause of the elevated heart rate to decide on the appropriate treatment, which could range from medications to surgery.