Showing posts with label angina. Show all posts

Pulmonary, Gastrointestinal, and Musculoskeletal, Not Just Cardiac

Musculoskeletal

Anyone who experiences chest pain often feels a sense of alarm. People have been taught to see a physician for chest pain because it may be a heart attack. There is nothing wrong with such a concern. However, it does not mean that all episodes of chest pain are from coronary artery disease. There are other causes, including non-cardiac ones.

Cardiac Causes

Cardiac chest pain that isn't a heart attack can involve the outside of the heart. Normally, it sits within a fibrous sac called the pericardium. This sac can become inflamed (pericarditis) from various causes, including infection (e.g. virus, tuberculosis), autoimmune conditions (e.g. rheumatoid arthritis, systemic lupus erythematosus), uremia from kidney failure, certain medications, and radiation injury. The pain is usually in the center of the chest and is notably worsened when one takes a deep breath (pleuritic chest pain), swallows, or lies down. In contrast, this same pain can be lessened with sitting up and leaning forward.

A physician may hear a frictional rub when listening to the heart with a stethoscope. In some cases, the physician may order an echocardiogram, ultrasound of the heart, to see if there is fluid accumulation around the heart. It may be a small or large amount. In the worse case scenario, the amount of fluid is large enough to squeeze the heart and impair blood flow. This can be corrected with insertion of a needle through the chest wall and into the pericardium to drain the fluid (pericardiocentesis).

Other cardiac causes for chest pain include angina, myocardial infarction, and aortic dissection, all of which have already been discussed elsewhere.

Pulmonary Causes

Chest pain involving the lungs is uncommon, but it can happen. Occasionally, it can occur with pneumonia, constriction of lung airways (bronchospasm), or a blood clot or other material that travels through the veins and gets stuck in the lung (pulmonary embolism). Another cause is air within the lung cavity (pneumothorax). This can happen with trauma, like from a bullet or knife puncturing the lung, but it can also occur spontaneously, particularly in those with chronic obstructive pulmonary disease (COPD) whose lungs are susceptible to popping at fragile portions. Besides air, fluid can accumulate in the lung cavity (pleural effusion) from various causes. Other conditions involve the lining of the lung cavity (pleura), such as a respiratory infection with coxsackie virus B.

Gastrointestinal Causes

Gastroesophageal reflux disease (GERD) can cause chest pain, particularly one that is more dull and lasts a while. Spasm of the esophagus produces chest pain that feels similar to cardiac angina.

Interestingly, nitroglycerin relieves esophageal spasm pain very much like cardiac anginal pain, which is why esophageal spasm is known to mimic angina. Pancreatitis, cholecystitis, and peptic ulcer disease are rare causes of chest pain.

Musculoskeletal Causes

Muscle strain, rib fracture, and inflammation of the rib cartilage (costochondritis) cause pain from the chest wall itself. This type of pain is worsened with breathing, movement, or pressure over the pain site. However, if it occurs in someone prone to cardiac angina, the clinical picture can become confusing.

Final Words

The purpose of this overview is to clarify that not all chest pain is related to the heart. This does not mean that chest pain can be self-diagnosed. Given the risk taken with ignoring chest pain, it is recommended that a physician evaluate the symptom for a definitive determination.

References

  • Goroll, Allan H. "Evaluation of Chest Pain." Primary Care Medicine: Office Evaluation and Management of the Adult Patient. 5th ed. Ed. Allan H. Goroll and Albert G. Mulley, Jr. Philadelphia: Lippincott, Williams, & Wilkins, 2006. 125-139.

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Nitric Oxide

nitric oxide
Nitric oxide is a very simple molecule consisting of one atom each of oxygen and nitrogen. It should not be confused with nitrous oxide which is made up of two nitrogen atoms and is commonly known as laughing gas – once a common anaesthetic.

Outside of the body it often occurs as a pollutant with the potential for causing illness. Much of this pollution comes from car exhaust.

Chemical Nature of Nitric Oxide

Because it is a small and simple molecule, nitric oxide is particularly suited to its function as a chemical messenger both between cells and within cells, easily passing through cell membranes.

Its chemical structure also includes a double bond, this makes it a reactive compound, which means it reacts with other chemicals easily and breaks down quickly. This is a further attribute of a good chemical messenger in that it can quickly be got rid of. However, it is this reactivity that makes nitric oxide a pollutant in the environment.

Biological Role of Nitric Oxide

There is a great deal of research currently being carried out on the many roles of nitric oxide. Sometimes these roles seem contradictory for example in the case of apoptosis – cell death, with nitric oxide sometimes promoting the process and at other times inhibiting it.

Two major areas of physiological function have emerged as having a particular reliance on nitric oxide. These areas are control of blood vessel action and immune function.

Nitric Acid and Blood Vessels

The walls of blood vessels incorporate a thin layer of muscle. Like other muscles in the body this muscle can contract and relax in response to signals from chemical messengers.

Key among these is nitric acid which causes the muscle to relax and therefore dilates the blood vessel to allow more blood to flow. This is important to maintain adequate glucose and oxygen supply to various tissues and organs and to regulate blood pressure.

This function of nitric acid has therapeutic value. The nitrite drugs such as glyceryl trinitrite are used to treat angina. This drug is converted to nitric oxide in the body which in turn relaxes the blood vessels supplying the heart and thus eases the pain.

Nitric Acid and Immunity

Phagocytes are white cells which are central to immune function. They ingest bacteria and destroy them. Phagocytes can produce nitric oxide which is toxic to bacteria. An unfortunate side-effect of this is damage to the body's own cells as well. This is the one of the reasons that inflammation – an integral part of the immune response – is so painful: there is quite a bit of cell damage going on, our own and bacteria.

The reactivity of nitric oxide comes in here. Because it's so toxic to all cells it needs to be produced quickly when needed and rapidly destroyed when its job is done. The body has a number of control systems that regulate the switching on and off of toxic but necessary substances like nitric oxide.
Because of the central role of nitric oxide in inflammation research has looked at the possibility of using exhaled nitric acid gas as a marker for inflammation in certain conditions such as asthma, atherosclerosis and rheumatoid arthritis.

This article is for information only. If you have any health concerns you should consult your doctor.

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