Cocaine Use and Endocarditis

Cocaine Use and Endocarditis

Endocarditis is an inflammation of the heart’s inner lining, known as the endocardium, which typically occurs as a consequence of some sort of infectious microorganism circulating in the bloodstream. For this reason, doctors and researchers also commonly refer to the condition as infective endocarditis. All intravenous (IV) drug users have increased risks for development of endocarditis-producing infection. However, IV cocaine use typically produces greater risks than other forms of IV drug use. In addition, IV cocaine users develop endocarditis in areas of the heart not usually damaged in people who use other IV drugs.

Endocarditis Basics

The heart is formed from three separate layers of tissue, known respectively as the epicardium, myocardium, and endocardium. The epicardium acts as a protective outer layer and sits adjacent to a larger protective sac, called the pericardium, which surrounds the heart. The myocardium sits beneath the epicardium; it contains the actual muscle that forms the bulk of the heart and gives the organ its pumping power. The endocardium sits beneath the myocardium on the organ’s inner surfaces, where it helps control the regularity of the myocardium’s pumping activities. In addition to the walls of the heart’s four chambers, the endocardium covers the surfaces of the valves between the chambers; it also joins directly to the interior linings of the heart’s blood vessels.

As indicated previously, infective endocarditis sets in when infectious microorganisms travel through the bloodstream and make their way to the endocardium. Under normal circumstances, these microorganisms would have no good way of attaching themselves to this lining while trying to deal with the heart’s chaotic internal environment. However, people who develop infective endocarditis usually have preexisting cases of another form of non-infection-related inflammation, called thrombotic endocarditis, which damages the endocardial surface and provides infectious agents with their required anchor points. Most of the microorganisms that produce infective endocarditis are bacterial agents such as Staphylococcus aureus (the infamous Staph A) and various members of the Streptococcus family. However fungal species can also produce the condition.

Endocarditis can damage the endocardium, myocardium, or the valves that control blood flow within the heart. If left untreated, potential consequences of an endocardial infection include heart failure related to extensive heart valve damage, a stroke caused by migrating blood clots or clumps of infectious material, additional spread of the infectious agent throughout the bloodstream, and the development of abscesses in the brain’s tissues.

Cocaine’s Effects

Endocarditis related to IV drug use is common enough that doctors and researchers have given the condition a separate name: intravenous drug abuse (IVDA) endocarditis. This form of endocarditis typically occurs when an IV drug user shares a single IV needle with other drug users, or fails in any other way to ensure the sterility of a needle prior to drug use. As noted previously, compared to other forms of IV drug use, IV cocaine use has a significantly greater tendency to lead to the onset of IVDA endocarditis.

According to a study published in 2004 in the Postgraduate Medical Journal (as well as a separate entry in the 2008 textbook Acute Coronary Syndrome: Multidisciplinary and Pathway-Based Approach), cocaine’s unique effects apparently stem from the drug’s ability to accelerate a user’s normal heart rate and produce damaging surges in a user’s normal blood pressure levels. Underlying these changes in cardiovascular (heart and blood vessel) health is cocaine’s excessive activation of the sympathetic nervous system, an involuntary system that usually helps the body avoid undue shifts in its internal environment. The heart rate and blood pressure changes associated with cocaine use apparently trigger tissue damage in the endocardium that makes the eventual development of infective endocarditis considerably more likely. In addition, cocaine use suppresses the immune system in ways that may contribute to the risks for infection in the endocardium or elsewhere in the body.

Considerations

In most cases of IVDA endocarditis that don’t involve cocaine use, infection only takes hold on the valves in the right side of the heart. However, people with cocaine-related IVDA endocarditis have a much greater tendency to develop infections in their left-side heart valves. IVDA endocarditis that involves the use of cocaine or any other drug is highly associated with transmission of the HIV virus, according to the authors of a study published in 2003 in the journal Current Infectious Disease Reports. Anywhere between 40 and 90 percent of all IV drug users with infective endocarditis also have an HIV infection.

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