Chronic Mitral Regurgitation
Copyright 2009
Definition
Chronic mitral regurgiation is a disorder in which the mitral valve fails is caused by rheumatic heart disease, mitral valve prolapse, atherosclerosis, hypertension, left ventricular enlargement, Marfan’s syndrome and other connective tissue disorders, endocarditis, cardiac tumors, acute mitral regurgitation, syphilis, or it may be congenital. Since the mitral valve connects the left atrium and ventricle, chronic mitral regurgitation is characterized by blood from the left ventricle back-flowing into the left atrium when the ventricle contracts. Therefore, the body will not receive as much blood as it needs and the heart will have to pump harder. This results in shortness of breath, palpitations, cough, fatigue, trouble breathing at night, syncope, edema (in lungs, legs, and feet), excessive urination at night, lightheadedness, irregular heart rhythms, low blood pressure, and rapid heartbeat. These symptoms devleop gradually; however, sometimes no symptoms are present. Chronic MR is diagnosed by palpation, sthethoscope, echocardiogram, transesophageal echocardiogram (TEE), cardiac color Doppler, MRI, cardiac catherization, chest X-ray, electrocardiogram, and chest CT. It is treated by surgery, anti-arrythmic drugs, vasodilators, diuretics, and digitalis. MedlinePlus Medical Encyclopedia: http://www.nlm.nih.gov/medlineplus/ency/article/000176.htm PeaceHealth: http://www.peacehealth.org/kbase/topic/special/aa143442/sec5.htm PRINCIPLES Blood flow will not stop unless there is a structure stopping it; hence, the concept of valves to allow blood to flow when it should flow and stop it from flowing when it shouldn’t flow. The left ventricle is the part of the heart that pumps blood to the entire body. It has two holes through which blood might flow–the left atrioventricular opening, heading to left atrium, and the aortic opening, heading to the aorta and the rest of the body. When the left ventricle has received blood from the left atrium and is ready to pump it to the body, it only wants the blood to travel through the aortic opening, and not back through the left atrioventricular opening from whence it has just came. Therefore, the valve over the left atrioventricular opening, the mitral valve, closes to block blood from flowing back into the left atrium. As mentioned above, however, blood will flow if not stopped, and thus if the mitral valve does not close properly, blood will flow back into the left atrium. The body’s cells need blood, and the left ventricle must supply them with as much as they need. It is in the best interest of the left ventricule to make as much blood flow through the aortic opening, where it travels to the body’s cells; if some blood doesn’t flow into the aortic opening, this is just wasted blood, and the left ventricle must work harder to compensate for that lost blood. This is the concept behind mitral regurgitation–if the mitral valve is not closing properly and is allowing blood to back-flow into the left atrium, the left ventricle must work harder to compensate for this lost blood which should have flowed into the aorta and from there to the rest of the body. ASSOCIATED DISEASES rheumatic heart disease, mitral valve prolapse, atherosclerosis, hypertension, left ventricular enlargement, Marfan’s syndrome and other connective tissue disorders, endocarditis, cardiac tumors, acute mitral regurgitation, and syphilis can cause chronic MR; diabetes and coronary artery disease can also increase one’s risk of getting it. MedlinePlus Medical Encyclopedia: http://www.nlm.nih.gov/medlineplus/ency/article/000176.htm PeaceHealth: http://www.peacehealth.org/kbase/topic/special/aa143442/sec5.htm PREDISPOSING FACTORS Age and hypertension put greater strain on the mitral valve. In addition, diabetes and Marfan’s syndrome can calcify the mitral valve’s base, rheumatic fever can scar the valve, and coroanry artery disease can affect the valve’s structure and cause cardiomyopathy. PeaceHealth: http://www.peacehealth.org/kbase/topic/special/aa143442/sec1.htm COMPLICATIONS Complications include endocarditis, heart failure, pulmonary emboli, stroke, clots, and arrythmias, including atrial fibrillation and lethal arrhythmias. MedlinePlus Medical Encyclopedia: http://www.nlm.nih.gov/medlineplus/ency/article/000176.htm LABORATORY TESTS Palpations can diagnose chronic mitral regurgiation if there is vibration over the heart, while a sthethoscope can pick up a murmur unique to this disorder. Rales, abnormal breath sounds, ankle swelling, enlarged liver, distended neck veins, and other signs of right-sided heart failure may also be present. MedlinePlus Medical Encyclopedia: http://www.nlm.nih.gov/medlineplus/ency/article/000176.htm IMAGING Imaging used to diagnosed chronic mitral regurgiations includes echocardiogram, transesophageal echocardiogram (TEE), cardiac color Doppler, MRI, cardiac catherization, chest X-ray, electrocardiogram, and chest CT. Enlargement of the left ventricle may also be seen. MedlinePlus Medical Encyclopedia: http://www.nlm.nih.gov/medlineplus/ency/article/000176.htm TREATMENT Surgery may be necessary for poor heart function, severe symptoms, and if the condition deteriorates. Medications used include anti-arrythmic drugs to control irregular heart rhythms, vasodilators to reduce the heart’s workload, digitalis to strengthen heartbeat, diuretics to remove excess fluid from lungs, antiobiotics to treat bacterial infection or to be taken before procedures such as dental work, and antiocoagulants and antiplatelet medications to fight clot formations if there is a possibility of one forming. A diet low in sodium can help. MedlinePlus Medical Encyclopedia: http://www.nlm.nih.gov/medlineplus/ency/article/000176.htm