Chemical found in medical devices weakens heartbeat

May 1st, 2009 - 5:51 pm ICT by IANS  

Washington, May 1 (IANS) Cyclohexanone, a chemical commonly used in the production of plastic devices like intravenous (IV) bags and catheters, weakened heart beats by 50 percent in rats.
Artin Shoukas’ personal experience with coronary bypass propelled his search for a root cause for the loss of taste. “I’m a chocoholic, and after my bypass surgery everything tasted awful, and chocolate tasted like charcoal for months,” he said.

Shoukas is professor of biomedical engineering, physiology and anesthesiology at Johns Hopkins.

Shoukas and Caitlin Thompson-Torgerson, postdoctoral fellow in anesthesiology and critical care medicine, suspected that the trigger for these side-effects might be a chemical compound of some kind.

Accordingly, Shoukas and his team took liquid samples from IV bags and bypass machines before they were used on patients.

The team analysed 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 leaked from the plastic.

Although the amount of cyclohexanone leaking 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 micro-litres of blood per heartbeat and had an average heart rate of 358 beats per minute, while rats injected with cyclohexanone pumped only about 150 micro-liters of blood per heartbeat with an average heart rate of 287 beats per minute.

Besides 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, said a Johns Hopkins release.

They also found that the reflex that helps control and maintain blood pressure is less sensitive after cyclohexanone exposure. Finally, the team observed increased fluid retention and swelling in the rats after cyclohexanone injections.

These new findings also suggest a possible new reason for common side-effects like loss of taste, short term memory loss linked with procedures that require blood to be circulated through plastic tubing outside the body, such as in cases of bypass surgery or kidney dialysis.

These findings appeared online this week in the American Journal of Physiology.

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