Shoulder pain is a common complaint, often dismissed as a minor muscle strain or joint issue. Discomfort originating in the heart can sometimes be perceived in the shoulder or arm, a phenomenon known as referred pain. Recognizing this type of pain is difficult because the source is misleading, but understanding its specific characteristics can be life-saving. This article details the unique sensations of heart-related shoulder pain and how to differentiate it from a simple orthopedic injury.
The Mechanism of Referred Cardiac Pain
Pain signals from internal organs, known as visceral pain, are often poorly localized by the brain. The reason pain from the heart can be felt in the shoulder or arm lies in the shared neural pathways within the spinal cord. Sensory nerves from the heart and the nerves that supply the shoulder and arm converge onto the same second-order neurons in the upper thoracic segments (T1 to T5). When the heart experiences distress, such as during a lack of oxygenated blood flow, the brain misinterprets the resulting electrical activity as coming from the more familiar somatic area, specifically the shoulder or arm. The result is pain perceived in a distant body part, which is why a person may have shoulder pain without any actual problem in the shoulder joint itself.
Specific Sensations of Heart-Related Shoulder Pain
Heart-related shoulder pain, whether from angina or a heart attack, is typically described as a deep, non-localized ache rather than a sharp, stabbing sensation. The discomfort often feels like a heavy weight, tightness, squeezing, or pressure. It is commonly felt in the left shoulder and may radiate down the inside of the left arm, sometimes extending to the back, neck, or jaw. The sensation may not be constant, sometimes going away and then returning over a period of minutes.
This discomfort may also be perceived as a general numbness. While the left side is classic, the pain can occasionally be felt in the right shoulder, both arms, or the upper back, especially in women. Importantly, the pain is not usually intensified by pressing on the shoulder joint or moving the arm in a specific direction.
Distinguishing Cardiac Pain from Musculoskeletal Issues
Differentiating cardiac shoulder pain from common musculoskeletal (MSK) problems, such as a rotator cuff tear or tendonitis, relies on recognizing key differences in how the pain behaves. MSK pain is typically localized, meaning the patient can often point to the exact spot where the pain originates. This type of pain almost always intensifies with certain movements, like lifting the arm overhead, or improves with rest and positional changes. A distinguishing feature is tenderness to touch, or palpation, which is almost always present in MSK injuries but absent in cardiac pain.
In contrast, cardiac pain frequently begins during physical exertion or emotional stress, when the heart’s demand for oxygen increases. Because the origin is the heart muscle, the pain persists regardless of how the shoulder is stretched, rotated, or rested. MSK pain often has a clear cause, such as a specific injury or chronic overuse, which is not the case for cardiac pain.
Cardiac discomfort, unlike a joint injury, is often accompanied by a sense of foreboding or a feeling of being unwell. While MSK pain can be severe, it rarely presents with systemic symptoms like a cold sweat or shortness of breath. MSK pain is also typically absent of the systemic symptoms that accompany cardiac events.
When to Seek Emergency Medical Attention
Shoulder pain that may be heart-related requires immediate emergency medical attention, especially if it is accompanied by other specific symptoms. Warning signs include discomfort in the shoulder, arm, or jaw combined with chest pressure, squeezing, or fullness that lasts for more than a few minutes. Sudden shortness of breath is also a serious symptom, which can occur even without chest discomfort. Pain that rapidly worsens, or that does not go away after a few minutes of rest, should be treated as a medical emergency.
Other signs necessitating emergency services are breaking out in a cold sweat, feeling light-headed or dizzy, and experiencing nausea or vomiting. Seek help right away, even if the shoulder pain is the only symptom or if the discomfort is mild, particularly if heart disease risk factors are present.