Chest pain pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aisha Adigun, B.Sc., M.D.[2]Nuha Al-Howthi, MD[3]

The cardiovascular system, respiratory system, part of the gastrointestinal system, and the great vessels give off afferent visceral input via common thoracic autonomic ganglia. Painful stimuli in any of the aforementioned systems are usually sensed as originating from the chest. However, due to the fact that afferent nerve fibers overlap in the dorsal ganglia, pain in the thorax may be experienced at any point between the umbilicus and the ear, as well as in the upper limbs.

• Chest pain is a warning of injury to a structure in the thoracic cavity.^[1]
• Because of the anatomy of the thoracic cav­ity and the proximity of the structures, locating the exact problem through the characteristics of the pain is diffi­cult. Any struc­ture in the thoracic cavity may be the source of chest pain.^[2]
• The free nerve endings suscepti­ble to multiple stimuli, are found in all the major structures in the thoracic cavity. The peripheral nerves conjugate toward the spinal nerves developing a plexus (cardiac plexus). These plexuses join and share common spinal nerves. Mul­tiple structures share corresponding spinal nerves. An example of this overlap­ping use of spinal nerves is the heart, which is innervated by cervical nerve root 8 through thoracic nerve root 4 and the esoph­agus, innervated by thoracic nerve roots 1 through 4.^[1]
• The cardiovascular system, respiratory system, part of the gastrointestinal system, and the great vessels give off afferent visceral input via common thoracic autonomic ganglia.
• Painful stimuli in any of the aforementioned systems are usually sensed as originating from the chest.
• However, due to the fact that afferent nerve fibers overlap in the dorsal ganglia, pain in the thorax may be experienced at any point between the umbilicus and the ear, as well as in the upper limbs.
• Chest pain due to either endothelial-dependent or independent mechanisms. The endothelium regulates vascular tone and growth by releasing endothelial-derived relaxing factors such as nitric oxide and also by releasing endothelial-derived vasoconstrictive factors such as endothelin. Several observations in the past 2 decades have led to the hypothesis that the endothelium plays an important role in the pathophysiology of angina.^[3]

• The pain could be visceral or somatic; vis­ceral pain is a diffuse, poorly localized pain arising from organs and linings of body cavi­ties, and it is referred to other sites. For instance, cholecystitis pain referred to the chest. Somatic pain from the skin and subcutaneous tissues are usually well localized and is characterized by constant, aching pain.
• Chest pain could be due to angina pectoris that is associated with transient episodes of myocardial ischemia.^[1]

• The ischemia is usually caused by the narrowing of the coronary ar­teries by atherosclerotic plaques. The chest pain is usually transient, lasting from 15 sec­onds to 15 minutes and is frequently associ­ated with activity, exertion, or stress. It is re­lieved with rest or sublingual nitroglycerin.^[1]

• Unstable angina is triggered by severe tran­sient myocardial ischemia that oc­curs because changes to an atherosclerotic plaque in the coronary artery that causes platelet aggregation and vasospasm, decreasing my­ocardial blood supply. There is evidence that suggests unstable angina precedes myocar­dial infarction.^[1]