A heart attack (myocardial infarction) occurs when blood flow to a section of the heart muscle is severely reduced or blocked. This lack of oxygen causes tissue damage, which is life-threatening if not treated quickly. A common and confusing aspect is pain felt away from the chest, known as referred pain. This distress signal is often mistakenly perceived by the brain as originating from a different part of the body, most notably the arm.
Referred Pain: Clarifying Left vs. Right Arm Involvement
The classic presentation of heart attack-related arm pain is most frequently associated with the left arm, a detail often highlighted in popular media. However, relying on this single location can be misleading and potentially dangerous, as the pain is highly variable. Discomfort can manifest in the right arm, both arms simultaneously, or radiate into the shoulders and upper back. The location of the pain alone should never be the deciding factor in seeking emergency medical help.
The sensation in the arm is typically described as a deep ache, a feeling of heaviness, or intense pressure, rather than a sharp, localized stab of pain. Individuals may report numbness, tingling, or a squeezing sensation that runs down the arm, often starting in the chest or shoulder. This discomfort is generally persistent, lasting for more than a few minutes. Unlike muscle strain, it does not improve with rest or a change in position, making the overall context of the symptoms important.
Understanding the Neurological Mechanism
The pain caused by a heart attack in the arm is rooted in the shared wiring of the nervous system. The process begins when oxygen-deprived heart tissue releases chemical signals that activate visceral afferent nerves. These nerves transmit sensation from the internal organs back to the spinal cord.
The heart’s sensory nerves enter the spinal cord at the thoracic segments, sharing a common pathway with somatic nerves from the arms and upper body (T1 to T5 dermatomes). When the visceral pain signal reaches the spinal cord, it converges onto the same ascending neurons used by the somatic nerves. The brain misattributes the incoming visceral pain signal to the more familiar location. This neurological cross-talk causes the brain to mistakenly perceive the heart’s distress as pain originating in the arm or shoulder.
Recognizing the Full Spectrum of Heart Attack Symptoms
While arm pain is a known indicator, a heart attack presents with a broader range of signs requiring prompt action. The most common symptom is discomfort in the center or left side of the chest. This is often described as a squeezing, fullness, or pressure that may last for several minutes or return intermittently. This chest discomfort can occur with or without accompanying arm pain.
Other signs include shortness of breath, which may happen before or simultaneously with chest discomfort. Pain or discomfort can also radiate to the jaw, neck, or upper back. Non-classic symptoms are more common in women, older adults, and people with diabetes. These can include unexplained fatigue, a sudden cold sweat, nausea, or lightheadedness. These subtle symptoms are easily mistaken for less serious conditions like indigestion, making awareness of the full spectrum of signs important.
Immediate Action: What to Do in an Emergency
Recognizing the signs of a heart attack requires an immediate and decisive response to prevent permanent damage to the heart muscle. If you or someone else is experiencing any combination of these symptoms, the single most important action is to call emergency services, such as 9-1-1, right away. Do not attempt to drive yourself to the hospital, as emergency medical personnel can provide life-saving care the moment they arrive.
While waiting for the emergency team, the individual should sit down and rest in a comfortable position to minimize the heart’s workload. If there is no known allergy or contraindication, chewing and swallowing a standard dose of aspirin (325 mg) or a few low-dose (81 mg) baby aspirins can be beneficial. Aspirin works to thin the blood, which may help break up the clot causing the blockage. Loosen any tight clothing and remain calm while following the instructions provided by the emergency dispatcher.