Toxic chemical found in medical devices impairs heart function

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Toxic chemical found in medical devices impairs heart function

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es-impairs-heart-function/_

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Researchers at the Johns Hopkins University School of Medicine have found

that a chemical commonly used in the production of such medical plastic

devices as intravenous (IV) bags and catheters can impair heart function in

rats. Reporting online this week in the American Journal of Physiology, these

new findings suggest a possible new reason for some of the common side

effects—loss of taste, short term memory loss–of medical procedures that

require blood to be circulated through plastic tubing outside the body, such as

heart bypass surgery or kidney dialysis. These new findings also have

strong implications for the future of medical plastics manufacturing.

In addition to loss of taste and memory, coronary bypass patients often

complain of swelling and fatigue. These usually resolve within a few months

after surgery, but they are troubling, sometimes hinder recovery, but

generally go away.

His personal experience with coronary bypass surgery propelled his search

for a root cause for the loss of taste phenomenon, reports principal

investigator Artin Shoukas, Ph.D., professor of biomedical engineering,

physiology and anesthesiology and critical care medicine at Johns Hopkins. **

I*m a

chocoholic, and after my bypass surgery everything tasted awful, and

chocolate tasted like charcoal for months.**

Shoukas and Caitlin Thompson-Torgerson, PhD, a postdoctoral fellow in

anesthesiology and critical care medicine suspected the trigger for these side

effects might be a chemical compound of some kind.

To test their theory, Shoukas and his team of researchers took liquid

samples from IV bags and bypass machines before they were used on patients. The

team analyzed the fluids in another machine that can identify unknown

chemicals and found the liquid to contain a chemical compound called

cyclohexanone. The researchers thought that the cyclohexanone in the fluid

samples

might have leached from the plastic. Although the amount of cyclohexanone

leaching from these devices varied greatly, all fluid samples contained at

least some detectable level of the chemical.

The researchers then injected rats with either a salt solution or a salt

solution containing cyclohexanone and measured heart function. Rats that got

only salt solution pumped approximately 200 microliters of blood per

heartbeat and had an average heart rate of 358 beats per minute, while rats

injected with cyclohexanone pumped only about 150 microliters of blood per

heartbeat with an average heart rate of 287 beats per minute.

In addition to pumping less blood more slowly, rats injected with

cyclohexanone had weaker heart contractions. The team calculated that

cyclohexanone

caused a 50 percent reduction in the strength of each heart contraction.

They also found that the reflex that helps control and maintain blood

pressure is much less sensitive after cyclohexanone exposure. Finally, the team

observed increased fluid retention and swelling in the rats after

cyclohexanone injections.

According to Thompson-Torgerson and Shoukas, they would like to figure out

how these side effects—decreased heart function and swelling—occur and to

what degree cyclohexanone is involved. Despite the findings in this study,

they emphasize that patients should listen carefully to the advice of

their physicians. **We would never recommend that patients decline this type of

treatment if they need it,** says Shoukas. **On the contrary, such

technologies are life-saving medical advances, and their benefits still far

outweigh the risks of the associated side effects. As scientists, we are simply

trying to understand how the side effects are triggered and what the best

method will be to mitigate, and ultimately remedy, these morbidities.**

Authors on the paper are

Caitlin S. Thompson-Torgerson, Hunter C. Champion, Lakshmi Santhanam, Z.

Leah Harris and Artin A. Shoukas, all of Johns Hopkins University School of

Medicine.

Reference:

Johns Hopkins, Chemical found in medical devices impairs heart function,

Press Release, May 1, 2009