Researchers at the Johns Hopkins University School of Medicine have discovered that a chemical commonly used in making plastic medical devices — from intravenous (IV) bags to catheters — can impair the heart function of rats.
The study, which has serious implications for the manufacturing of medical plastics, appears online this week in the American Journal of Physiology and addresses one of the common complaints from coronary bypass patients, who often report short-term memory loss or a lack of taste function after medical procedures that require blood to circulate in plastic tubing outside the body. Some of these procedures include heart bypass surgery or kidney dialysis, and while side effects usually resolve within a few months of the surgery, they can sometimes hinder patients' recovery.
The researchers suspected that the cause of these side effects might be some kind of chemical compound. So they took liquid samples from IV bags and bypass machines before they were used on patients. This led to the discovery of the presence of cyclohexanone, a chemical compound which researchers thought might have leached into the liquid from the plastic. All fluid samples had 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 tracked their heart function. Rats that received only salt solution pumped more microliters of blood per heartbeat and had a faster average heart rate.
The research team also calculated that cyclohexanone caused a 50 percent reduction in the strength of each heart contraction, while the reflex that helps control blood pressure was much less sensitive after exposure to the chemical compound. The researchers also observed increased fluid retention and swelling in the rats after cyclohexanone injections.
Despite their findings, the researchers take great pains to emphasize that patients should always heed their doctors' advice in relation to medical procedures. And they say more research is needed to fully understand the effects of cyclohexanone. "We would never recommend that patients decline this type of treatment if they need it," said principal investigator Artin Shoukas, professor of biomedical engineering, physiology and anesthesiology and critical care medicine at Johns Hopkins, in a press release announcing the findings.
"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."
And it was Shoukas' personal experience with coronary bypass surgery that caused him to research the root cause for the loss of taste phenomenon. "I'm a chocoholic," he said. "And after my bypass surgery everything tasted awful, and chocolate tasted like charcoal for months."
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