Heartburn, the sensation caused by acid reflux, occurs when stomach acid flows back into the esophagus. Because the esophagus and the heart are located close together in the chest, the discomfort from acid reflux, known medically as Gastroesophageal Reflux Disease (GERD), can easily mimic the symptoms of a serious cardiac event. This overlap in sensation, especially when it involves radiating pain in areas like the arm, shoulder, or jaw, is why chest pain should never be dismissed. Understanding the underlying physiological mechanisms and distinguishing symptom patterns is important in knowing when to seek urgent medical attention.
The Mechanism of Referred Pain
Pain felt in a location away from its actual source, such as arm discomfort originating from the esophagus, is known as referred pain. This phenomenon occurs because the sensory nerves carrying signals from internal organs (viscera) are not as numerous or precise as those from the skin and muscles. The brain is therefore less skilled at pinpointing the exact location of visceral pain.
The neurobiological explanation involves shared pathways in the spinal cord, known as the convergence-projection theory. Visceral sensory nerves from the esophagus and somatic sensory nerves from the arm and chest wall travel to the same second-order neurons within the spinal cord’s dorsal horn. When acid irritates the esophageal lining, the pain signal travels along the visceral nerves to the shared spinal segment.
The brain, being more accustomed to receiving signals from the somatic nerves, incorrectly interprets the incoming pain signal as originating from the more familiar external location, such as the arm or shoulder. This misinterpretation causes the burning sensation from the esophagus to be perceived as radiating discomfort in the left arm. This mechanism explains why pain from non-cardiac sources like GERD can sometimes imitate the symptoms of a heart attack.
Distinguishing Cardiac Pain from Heartburn
Differentiating between chest pain from a heart attack (myocardial infarction or MI) and pain from severe acid reflux is important. While both conditions cause chest discomfort, the location and quality of the pain often differ significantly. Heartburn typically presents as a burning sensation that travels up the chest and into the throat, sometimes leaving a sour or acidic taste. Cardiac pain, conversely, is frequently described as a severe pressure, tightness, heaviness, or a crushing sensation felt over a broad area of the chest.
The context and triggers surrounding the pain offer further clues to the origin of the discomfort. Heartburn symptoms are often triggered by large meals, consuming specific foods like spicy or fatty items, or lying down too soon after eating. Pain caused by a heart issue, such as angina, often comes on during physical exertion or emotional stress. If the chest discomfort improves rapidly with rest, it suggests a heart-related issue like angina, whereas heartburn may improve with antacids.
Associated symptoms accompanying the chest discomfort provide another layer of distinction. Heartburn is commonly associated with digestive symptoms like burping, bloating, or acid regurgitation. A heart attack is more likely to be accompanied by non-digestive symptoms, including cold sweats, shortness of breath, sudden lightheadedness, and nausea.
The way pain radiates can also be helpful, though not definitive. While heartburn is generally limited to the chest and throat, cardiac pain often spreads to the arm, neck, jaw, or back, particularly the left arm. Because of the shared nerve pathways, however, either condition can cause pain in the left arm, making reliance solely on this symptom inadvisable. Heartburn usually subsides after a few minutes or hours, especially after taking antacids, while cardiac pain tends to persist or worsen.
Urgent Symptoms Requiring Immediate Medical Attention
If chest pain occurs, seeking medical attention immediately is the safest course of action. This is particularly true if the pain is new, unexplained, or severe, as rapid treatment can be life-saving in the event of a heart attack. Any sudden, severe pressure, squeezing, or crushing sensation felt under the breastbone should prompt an immediate call to emergency services.
Do not attempt to self-assess or wait for the pain to subside if the chest discomfort is accompanied by certain warning signs. These include:
- Pain that radiates widely to the jaw, back, or shoulder.
- Shortness of breath.
- Sudden lightheadedness or fainting.
- Cold sweat or excessive sweating.
- Nausea alongside the chest pain.
If the chest pain lasts longer than a few minutes or gradually increases in intensity, seek professional help. Paramedics arriving by ambulance can begin preliminary testing, such as an electrocardiogram (ECG), to check the heart’s rhythm and detect a heart attack faster than if one were to drive to the hospital. When in doubt about the cause of chest pain, the concern for a serious cardiac event must always take priority until medical professionals prove otherwise.