Why heart attack pain spreads to the arm and jaw, and when it does not

How shared wiring creates referred pain

Heart muscle has sensory nerves but no detailed map in the brain. Cardiac pain fibres travel with sympathetic nerves back to the spinal cord, mainly upper thoracic segments. There they converge on the same second-order neurons that receive signals from the skin and muscle of the chest and inner arm.

The brain is used to interpreting signals on those shared neurons as coming from the body surface, so ischaemic heart pain is projected to the chest wall, shoulder and arm. Visceral pain is also poorly localised, which is why clients often describe pressure, squeezing or heaviness rather than a sharp point of pain. Some clients deny pain entirely but admit to a tightness or discomfort when asked in different words.

Why the jaw, neck and upper abdomen can be involved

Jaw, neck and tooth pain are harder to explain by thoracic segments alone. Cardiac signals also travel in vagal fibres, and one proposed explanation is convergence with nerves that serve the face and jaw, but the exact pathway in humans is not settled. What matters clinically is that angina can be felt as toothache or jaw ache. The same convergence principle explains referred pain elsewhere, such as diaphragmatic irritation felt at the shoulder tip.

NHLBI and CDC list arm, shoulder, back, neck, jaw and upper abdominal discomfort among heart attack symptoms. An exam item describing jaw pain with sweating and nausea is therefore not describing a dental problem by default. Treat the location as a clue to the heart until the cardiac cause has been assessed.

Atypical presentations follow the same physiology

Because perception depends on nerve signalling, anything that changes it alters the presentation. NHLBI notes that people with diabetes are more likely to have silent heart attacks with mild or no symptoms, and older adults may present with shortness of breath rather than pain. Women more often report unusual fatigue, nausea or vomiting.

For assessment, ask about discomfort anywhere from jaw to upper abdomen, breathlessness, sweating, nausea and sudden fatigue, not only chest pain. A client who denies chest pain may still be having an infarction. Record onset, quality, radiation and associated symptoms, and follow the facility chest pain pathway, including prompt electrocardiogram and escalation. Reassess after any intervention, because changing or recurring discomfort is itself information.

What referred pain cannot tell the nurse

Referred pain points toward the heart but does not establish the diagnosis. Musculoskeletal strain, gallbladder disease, oesophageal spasm and anxiety can all cause chest, arm or upper abdominal discomfort. The nurse's job is not to rule these in or out from symptom location, but to recognise when cardiac assessment must come first.

Pain location also does not predict severity. A client with small, vague discomfort can have significant ischaemia, while dramatic pain can have another cause. Trends matter more: discomfort that builds, recurs at rest or comes with breathlessness, sweating, hypotension or a new arrhythmia warrants immediate escalation under the local protocol.

Work a hypothetical scenario

Imagine a hypothetical client with long-standing diabetes who reports aching in the left jaw, nausea and feeling unusually tired, with no chest pain. Options are to suggest a dental review, give an antiemetic and recheck later, or initiate the chest pain protocol, obtain an electrocardiogram and notify the provider.

Initiating the chest pain protocol is the safest choice because jaw pain, nausea and fatigue can all be referred or atypical cardiac symptoms, and diabetes increases the chance of a muted presentation. The dental and antiemetic options treat the symptom while delaying recognition of possible myocardial ischaemia.

Sources and further reading

NHLBI: Heart Attack Symptoms. Arm, jaw, neck, back and upper abdominal symptoms; fatigue in women; silent attacks in older adults and people with diabetes.

CDC: Heart Attack Symptoms, Risk, and Recovery. Jaw, neck, back, arm and shoulder discomfort and other symptoms more common in women.

MSD Manual Professional: Angina pectoris. Radiation to the left shoulder and inner arm, back, throat, jaw, teeth and upper abdomen, and atypical presentations in women and older adults.

Referred pain: characteristics, possible mechanisms, and clinical management. Convergence-projection theory: nociceptive afferents converging on shared second-order spinal neurons so pain is felt in somatic areas.