17.8: Heart Abnormalities and Treatments
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Heart Abnormalities and Treatments
Coronary Artery Disease
Coronary artery disease is the leading cause of death worldwide. It occurs when there is a buildup of plaque (a fatty material including cholesterol, connective tissue, white blood cells, and some smooth muscle cell) within the walls of the arteries that serve the myocardium of the heart. This buildup obstructs the flow of blood and decreases the flexibility or compliance of the blood vessels serving the heart tissue. This condition is called atherosclerosis, a hardening of the arteries that involves the accumulation of plaque. As the coronary blood vessels become occluded, the flow of blood to the tissues of the heart becomes restricted, a condition called ischemia that causes the cells to receive insufficient amounts of oxygen, called hypoxia. If untreated, coronary artery disease can lead to myocardial infarction, also known as a heart attack (death of cardiac muscle as a result of ischemia and hypoxia).
Above: (Left) Illustration of normal blood flow through the coronary arteries versus abnormal blood flow through coronary arteries with coronary artery disease. (Right) Following an angioplasty procedure to remove plague blockage from a coronary artery, a stent is often used to hold the artery open to maximize blood flow through the vessel to prevent ischemia, hypoxia, and myocardial infarction.
Angioplasty is a procedure in which the occlusion is mechanically widened with a balloon. A specialized catheter with an expandable tip is inserted into a superficial vessel, normally in the leg, and then directed to the site of the occlusion. At this point, the balloon is inflated to compress the plaque material and to open the vessel to increase blood flow. Then, the balloon is deflated and retracted. A stent consisting of a specialized mesh is typically inserted at the site of occlusion to reinforce the weakened and damaged walls. Stent insertions have been routine in cardiology for more than 40 years.
Coronary Artery Bypass
Another treatment for coronary artery disease is coronary bypass surgery. This surgical procedure grafts a replacement vessel obtained from another, less vital portion of the patient's body to bypass the occluded area. This procedure is clearly effective in treating patients experiencing myocardial infarction, but overall does not increase longevity. Nor does it seem advisable in patients with stable although diminished cardiac capacity since frequently loss of mental acuity occurs following the procedure.
Above: Diagram of single, double, triple, and quadruple coronary artery bypass grafts.
Atrial Septal Defect
Above: (Left) Diagram of patent foramen ovale where foramen ovale is not fully covered at birth and (right) a catheter procedure can be used to insert a device to cover foramen ovale.
One very common form of interatrial septum pathology is patent foramen ovale, which occurs when foramen ovale does not close at birth, and the fossa ovalis is unable to fuse. The word "patent" is from the Latin root patens for “open.” It may be benign or asymptomatic, perhaps never being diagnosed, or in extreme cases, it may require surgical repair to close the opening permanently. As much as 20–25% of the general population may have a patent foramen ovale, but fortunately, most have the benign, asymptomatic version. Patent foramen ovale is normally detected by auscultation of a heart murmur (an abnormal heart sound) and confirmed by imaging with an echocardiogram. Despite its prevalence in the general population, the causes of patent ovale are unknown, and there are no known risk factors. In nonlife-threatening cases, it is better to monitor the condition than to risk heart surgery to repair and seal the opening.
Where medical interventions are necessary to correct patent foramen ovale, a catheter procedure may be used to implant a device to close the foramen in the interatrial septum. Device closure involves threading the device, attached to a catheter, into a vein in the groin and through the blood vessels until it reaches the heart and can be implanted over the foramen. Another more invasive procedure would involve surgically opening the heart and stitching up the foramen in the interatrial septum.
Attributions
- "Anatomy and Physiology" by J. Gordon Betts et al., OpenStax is licensed under CC BY 4.0
- "Medical gallery of Blausen Medical 2014" by Blausen.com staff is licensed under CC BY 3.0