A chemical used to join plastic medical device components isthe target of a tough new report from engineering researchers at Johns Hopkins University.

The researchers report a chemical commonly used in the joining ofPVC parts for medical plastic equipment can impair heart function in rats.These findings, the scientists say, suggest a possible new reason for some ofthe common side effects, such as loss of taste and short-term memory loss, frommedical procedures that require blood to be circulated through plastic tubingoutside the body.

"We have tested primarily devices made from PVC, either softor hard," says Artin A. Shoukas, Director of the Center forBioEngineering Innovation and Design at the Johns HopkinsUniversity-School of Medicine. "(These include) cardiopulmonary bypassequipment (heart lung machine), dialysis equipment, ECMO and IV bags." ECMOstands for extracorporeal membrane oxygenation, a technique that provides oxygen to blood for newborns with inadequatelung function.

In a press release issued by Johns Hopkins, the scientists state: "These new findings also have strong implications for the future ofmedical plastics manufacturing."

In addition to loss of taste and memory, the Johns Hopkinsresearchers say coronary bypass patients often complain of swelling andfatigue. These problems usually resolve within a few months after surgery, butthey are troubling and sometimes hinder recovery. These symptoms generally go away, according to the researchers.

Dr. Shoukas's personal experience with coronary bypasssurgery propelled his search for a root cause for the loss-of-taste phenomenon."I'm a chocoholic, and after my bypass surgery everything tasted awful, andchocolate tasted like charcoal for months," he says. Shoukas and CaitlinThompson-Torgerson, a postdoctoral fellow in anesthesiology and critical caremedicine, say they suspected the trigger for these side effects might be achemical compound.

The researchers took liquid samples from IV bags and bypassmachines and analyzed the fluids in another machine. They found cyclohexanoneleaching from these devices. All fluid samples contained at least somedetectable level of the chemical. Cyclohexanone is commonly used joining PVCcomponents in medical tubing and devices.

The researchers then injected rats with either a saltsolution or a salt solution containing cyclohexanone and measured heartfunction. Rats that got only salt solution pumped approximately 200 mLof blood per heartbeat and had an average heart rate of 358 beats per minute,while rats injected with cyclohexanone pumped only about 150 mL ofblood per heartbeat with an average heart rate of 287 beats per minute.

The team calculated cyclohexanone caused a 50-percentreduction in the strength of each heart contraction. They also found thereflex that helps control and maintain blood pressure is much less sensitiveafter cyclohexanone exposure. Finally, the team observed increased fluidretention and swelling in the rats after cyclohexanone injections.

"We would neverrecommend that patients decline this type of treatment if they need it," saysShoukas. "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 aretriggered and what the best method will be to mitigate and ultimately remedythese morbidities."

This study was funded by the Bernard A. & Rebecca S.Bernard Foundation, the American Heart Association, the W.W. Smith Foundation,the National Institutes of Health, the Pulmonary Vascular Research Institute,the American College of Cardiology, the ShinChun-Wang Young Investigator Award, the American Physiological Society, theJoyce Koons Family Cardiac Endowment Fund and funds from Dr. Shoukas.

A spokesman for the American Chemistry Council had nocomment on the report.  A spokesman forthe Society of Plastics Industry (SPI) says, "We see this as a non-issue. Theseare life-saving devices."