Valvular heart disease refers to a number of diseases and disorders of one or more of the heart’s valves. The heart’s valves are flaps made of tissue that regulate the flow of blood through the heart’s four chambers by opening and shutting in a timely manner. When functioning properly, they prevent blood from flowing back into a chamber when closed.
The four heart valves are:
- Mitrial valve – located between the left ventricle and left atrium, it is the only valve with two cusps (flaps).
- Tricuspid valve – located between the right ventricle and right atrium, it is made up of three different sized cusps.
- Aortic valve – opens to allow blood to leave from the left ventricle to the aorta (the main artery of the body) and then closes to prevent blood from flowing backward into the left ventricle.
- Pulmonary valve – located between the pulmonary artery and right ventricle, it allows blood to flow out of the heart and into the lungs through the pulmonary artery. It then closes to prevent blood from flowing back into the right ventricle.
There are several heart diseases and other causes that can lead to valvular heart disease. Multivalvular heart disease occurs when more than one of the heart’s valves is involved. In both valvular and multivalvular heart disease, however, at least one of the following specific conditions listed below is present.
Causes range from infections to congenital abnormalities. The most common cause is rheumatic fever, an inflammatory disease that can develop after an infection with Streptococcus bacteria. Other common causes include infective endocarditis, an infection and inflammation of the endocardium (inner layer of heart tissue), heart attacks, deposits of calcium in the heart that occur with aging, connective tissue disorders such as myxomatous degeneration, carcinoid syndrome (in which a tumor secretes large amounts of serotonin), Marfan’s syndrome, and the use of drugs, mainly appetite suppressants.
Drugs that have gained widespread attention for having a potential of causing valvular heart problems include Fenfluramine (Pondimin), dexfenfluramine (Redux), phentermine, cabergoline (Dostinex, Cabaser), pergolide (Permax), ergotamine (Ergomar), and methysergide (Sansert).
Fenfluramine, dexfenfluramine, and phentermine
In 1997, after physicians became concerned that fen-phen (abbreviation for the combination of weight-loss supplements fenfluramine and phentermine) could affect heart valves, the maker of fenfluramine withdrew the drug from the market. Dexfenfluramine, which is also used in drug combinations referred to as fen-phen, was also mentioned in the US Food and Drug Administration (FDA) advisory that prompted its withdrawal.
These drug combinations work by increasing the level of the neurotransmitter serotonin, which regulates appetite and mood. But the same mechanism (activity at the 5-HT2B serotonin receptors of cardiac myocytes) that disrupts the vesicular storage of serotonin and gives a feeling of fullness can also affect blood vessels and heart valves.
Often used to manage prolactinomas (non-cancerous pituitary tumors that produce a hormone called prolactin) when bromocriptine proves ineffective. It is sometimes used off-label together with SSRI antidepressants to counteract some of their side effects, by some bodybuilders to control gynecomastia (excessive development of the male breasts), which can be caused by the use of certain anabolic steroids, and for Parkinson’s disease. Among its many potential side effects, however, cabergoline increases the risk of valvular regurgitation and other valvular dysfunctions when used in the higher doses required for treatment of Parkinson’s.
Like cabergoline, pergolide was also used to treat the tremors, spasms, stiffness, and poor muscle control of Parkinson’s. But unlike cabergoline, pergolide did not have another FDA approved use, so due to the serious valvular damage that was uncovered after its approval, it was withdrawn from the market in March 2007.
Ergotamine and Methysergide
Due to the same mechanism that increases serotonin levels in the blood as activated by the drugs mentioned above, these drugs can also cause proliferative valve disease.
Depending on the type of valvular heart disease, it may be diagnosed using x-rays, echocardiography, which uses sound waves to create inmages of the heart, electrocardiography (EKG), which records electrical charges in the heart during the heartbeat, and/or cardiac catheterization, in which a small tube is inserted into the heart through an artery to measure blood pressure within the heart.
A patient who has a history of using appetite suppressants or other drugs that raise the serotonin level in blood may need to have an EKG taken or undergo further testing if exhibiting symptoms of valvular heart disease. Symptoms may include swelling, shortness of breath, and significant fatigue.
Treatment also varies depending on the specific condition and may involve rest, medication, and/or surgery. Some studies have shown that drug-induced valvular heart problems frequently improve or at least do not worsen some time after discontinuing use of the offending drug.