Asthma is a chronic inflammatory disease that narrows the airways, making breathing difficult. Tachycardia is defined as a resting heart rate exceeding 100 beats per minute. Asthma can cause a rapid heart rate through two primary mechanisms. This link arises either from the body’s physiological response to breathing difficulty or as an expected side effect of the medication used during an acute attack. Understanding these two distinct mechanisms is important for managing this common respiratory condition.
The Body’s Stress Response During an Attack
An asthma exacerbation triggers events that increase heart rate. When airways constrict, the body struggles to take in enough oxygen, leading to hypoxia. To compensate for this lack of oxygen, the heart works harder and faster to circulate limited oxygen to vital organs.
This effort is driven by the sympathetic nervous system, the body’s “fight or flight” response. The nervous system releases stress hormones, primarily adrenaline (epinephrine). These hormones act on the heart to increase the force and speed of its contractions. This rapid pulse rate reflects the body’s attempt to survive respiratory distress by maximizing oxygen delivery.
The severity of the attack correlates directly with the degree of tachycardia experienced. A rapid heart rate, rapid breathing, and sweating are clinical signs of a severe episode. The increased work of breathing and the psychological anxiety of suffocation further intensify this response, pushing the heart rate higher.
The combination of physical struggle and psychological stress elevates the heart rate. While the heart’s increased pumping action is protective, it places strain on the cardiovascular system. This physiological mechanism is separate from medication effects and represents the direct strain of the disease state.
Tachycardia Caused by Asthma Medication
The primary cause of a rapid heart rate in people with asthma is often the treatment itself, specifically rescue inhalers. These quick-relief medications, such as albuterol, are short-acting beta-agonists (SABAs). SABAs are effective sympathomimetics that mimic stress hormones to quickly open the airways.
The therapeutic effect stimulates beta-2 adrenoceptors on the smooth muscles surrounding the bronchi, causing bronchodilation. However, these drugs are not perfectly selective and also activate beta-1 receptors found in the heart. This unintentional stimulation of cardiac receptors directly causes an increase in heart rate and occasionally palpitations.
This side effect is short-lived and dose-dependent. It is most noticeable immediately after use and subsides as the drug concentration decreases. An increase in heart rate after using a rescue inhaler is a common and expected sign that the medication is active. If a patient uses the inhaler more frequently or takes higher doses, the cardiac stimulation is more pronounced.
The transient tachycardia from a SABA is generally safe for most users, but it emphasizes the importance of proper asthma control. Frequent reliance on rescue inhalers suggests that underlying inflammation is poorly managed. Consulting a physician about inhaler frequency helps ensure controller medications are adjusted to minimize the need for quick-relief doses.
When Rapid Heart Rate Requires Medical Attention
A mild, temporary increase in heart rate after using a rescue inhaler is expected. However, sustained heart rhythm changes or those accompanied by concerning symptoms warrant immediate medical evaluation. The expected tachycardia from an inhaler typically resolves quickly, usually within minutes to an hour.
Immediate medical attention is necessary if the rapid heart rate is accompanied by new or worsening chest pain. Urgent assessment is also required if the fast, irregular heartbeat does not quickly return to normal after asthma symptoms are relieved.
Warning Signs Requiring Immediate Care
If the rapid heart rate is present, seek immediate care if you experience:
- New or worsening chest pain.
- Feeling dizzy, lightheaded, or faint, which may indicate poor blood circulation.
- A fast, irregular heartbeat that does not quickly return to normal.
- Severe sweating, or a pale or bluish tint to the lips or face.
- An inability to speak in full sentences.
If the asthma attack itself is severe, a rapid pulse rate that does not improve after using rescue medication signals a medical emergency. In these situations, tachycardia indicates severe respiratory distress, requiring immediate professional intervention.