Rib fracture is a common injury resulting from a blow to the thoracic cavity. The 1st rib is rarely broken, but when it is the result can be damage of the subclavian vessels and nerves of the brachial plexus. The ribs in the middle portion of the thoracic cage are most often broken due to trauma or crushing injury. Fracture of these ribs may result in injuries to vital organs (spleen or lung). Sometimes multiple ribs are fractured in the same incident, which can enable the free movement of a large portion of the anterior thoracic wall (a condition known as flail chest--seen in the image on the left). Such an injury would be very painful and impair ventilation.
The pericardium is a double-layered, fibrous sac that contains the heart and the roots of the great vessels (superior and inferior vena cavae, aorta, pulmonary trunk, pulmonary veins). The two layers are the fibrous pericardium and the serous pericardium. The serous pericardium is further divided into the parietal and visceral layers. These layers function to lubricate the heart, preventing friction during the organ's activity . The fibrous pericardium is composed of connective tissue, which also protects the heart by attaching it to the surrounding walls (including the diaphragm via the central tendon). It also acts to help prevent blood overflow.
Fluid can accumulate in the limited space of the pericardium (pericardial effusion), which can lead to a limitation of the expansion of heart, which can be thought of as increased pressure on or compression of the organ. If the heart cannot reach its full expansion, blood flow to the heart itself will be limited, which can result in a decrease in cardiac output. This heart compression is known as Cardiac tamponade, and can be deadly because of the reduction of blood flow to the heart, as well as the rest of the body. The solution is immediate pericardiocentesis, in which the fluid is removed from the pericardium, allowing the heart to expand normally, and for the ventricles to output sufficient amounts of blood.
The valves of the heart prevent back-flow of blood during the cardiac cycle. The are four valves in the human heart, two atrioventricular valves and two semilunar valves. The atrioventricular valves prevent backwards flow from the ventricles into the atria, and are known as the tricupside valve (right) and mitral valve (left). The semilunar valves prevent back-flow of blood from the arteries leaving the heart into the ventricles from which they came, and these are known as the aortic valve (left) and pulmonary valve (right).
Some individuals experience valvular heart disease, which is either a narrowing (stenosis) or insufficiency of the valve itself. These defects can reduce the heart's ability to pump blood efficiently. In stenosis, the heart valve does not open fully, which results in sluggish blood flow from chamber to chamber. Insufficiency of the valve is the opposite in that it occurs when the valve does not close fully, which allows some blood to flow back into the chamber from which it came. Depending of the degree of severity, duration, and location of these valvular problems, they can run the gambit from basically harmless to potentially fatal. If other treatment options fail, the defective valve can be replaced through valvuloplasty, in which synthetic material or xenografts (from other animals) are used to replace the faulty valve.
References
Moore et al. "Clinically Oriented Anatomy" (2010) 6th ed
http://www.ambulancetechnicianstudy.co.uk/chestinj.html
http://www.healthcentral.com/heart-disease/h/minimally-invasive-aortic-valve-replacement.html
http://www.nlm.nih.gov/medlineplus/ency/imagepages/18123.htm
Well Gavinator, what an interesting and disjointed post. I'm going to highlight something that you are probably already familiar with, Pericarditis.
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Interestingly, Pericarditis is often thought to be a precursor to pericardial effusion. Therefore, if there was a specific diagnostic tool for percarditis, it might be possible to prevent or at least halt the progression to percardial effusion and cardiac tamponade. Something to think about.
One common valve disease is mitral valve prolapse. Valves associated with this condition are either enlarged or "floppy". During systole, the insufficient valve allows blood to flow back into the left atrium. The most common characteristic of this condition is a heart murmur when listening to heart sounds. It occurs in 1 our of every 20 people and more commonly found in young females. It can become a burden on patients if they are experiencing chest pain and fatigue.
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