Particulate Air Pollution Increases Risk in Patients With Coronary Heart Disease
Individuals with established coronary artery disease were more likely to exhibit exercise-induced ST-segment depression when the air was polluted with fine and ultra fine particles, according to studies conducted by Finnish and German researchers. In a report in this week’s issue of Circulation (Circulation. 2002;106:933–938), the researchers, led by Julia Pekkanen, MD, of the National Public Health Institute Unit of Environmental Epidemiology in Kupio, Finland, wrote, “We observed an association between fine and ultrafine particulate air pollution and the risk of exercise-induced ST-segment depression among subjects with coronary heart disease. Ambient particles of different sizes might act independently due to their different sources or potentially through different mechanisms. The present results suggest that the effect of particulate air pollution on cardiovascular morbidity is at least partly mediated through increased susceptibility to ischemia and provide a plausible biological link between ambient levels of particulate matter and risk of mortality and mortality attributable ischemic heart disease.”
In their study, 45 subjects with coronary artery disease underwent repeated biweekly submaximal exercise tests over a 6-month period. During this time, 71 exercise-induced ST-segment depressions >0.1 mV occurred. They found that levels of particulate air pollution 2 days before the clinic visit were significantly associated with an increased risk of ST-segment depression during the exercise test.
In an accompanying editorial (Circulation. 2002;106:890–892), Richard L. Verrier, PhD, Murray A. Mittleman, MD, DrPH, and Peter H. Stone, MD, all of Harvard Medical School in Boston, Mass, noted that, “The importance of this observation is that it highlights myocardial ischemia as a significant potential mechanism responsible for the adverse cardiac outcomes associated with poor air quality. It remains unclear whether ischemia contributes to the adverse cardiac outcomes observed in epidemiologic studies through a mechanism related to plaque rupture leading to an acute coronary syndrome and/or to precipitation of life-threatening arrhythmias.”
The authors of the editorial believe the small size of the study makes it less convincing, however, and less applicable to larger populations in various cities in which the mixtures of particular air pollution can differ.
“The problem of particulate air pollution is pervasive and growing. An even greater concomitant toll on public health from this insidious contributor to cardiac disease can be anticipated. The American Heart Association, National Institutes of Health, and regulatory agencies have an important opportunity through education, funding, and regulation of clean air standards to exert a major impact on cardiovascular health,” they wrote.
Congress Works to Reduce Nursing Shortage
A bill passed by the US House and Senate in late July and signed by President Bush on August 1, 2002, is aimed at increasing the amount of people who seek nursing as a career.
The Nurse Reinvestment Act features several grant programs aimed at nursing training and retention, according to an article in the August 12, 2002, issue of American Medical News. The bill received the praise of the American Medical Association’s chair-elect William Plested, III, MD. “This is what has to be done,” he said, “and this is the time to do it. The shortage is absolutely real. It is incredibly important that this type of bill has been passed.”
The need for this kind of investment and more was underscored August 7, 2002, with the release of a report from the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) that noted that the growing shortage of nurses working in US hospitals is putting patients’ lives at risk. A Joint Commission Expert Roundtable proposed solving the problems by changing the workplace in which nurses function, creating a clinical foundation for nursing educational preparation, and making it financially advisable to healthcare organizations to invest in high-quality nursing care.
As indicators that the nursing shortage is becoming critical, the JCAHO group noted that the American Hospital Association reports that there are 126 000 nursing positions currently open in hospitals across the country and that 56% of hospitals report they use agency or traveling nurses—at great expense—to fill vacancies. The Service Employees International Union notes that, on average, nurses work an extra eight-and-a-half weeks of overtime per year.
“The need for solutions to this problem is particularly urgent,” said Dennis S. O’Leary, MD, President of the JCAHO, in a released statement. “We must as a country understand not simply what needs to be done, but who specifically is responsible for getting each task done. Otherwise, we face a future in which patient safety and health care quality will be significantly compromised.”
The full report from the JCAHO Health Care at the Crossroads is available at http://www.jcaho.org/news+room/news+release+ archives/health+care+at+the+crossroads.pdf.
Bioengineered Heart Muscle Beats In Vitro
An experimental, beating model of the heart is the product of collaboration between a cardiologist and an orthopedist at the University of North Carolina (UNC) at Chapel Hill, according to a report presented at the World Congress of Biomechanics in Calgary, Canada, on August 5, 2002.
The new model system is a bioartificial trabeculum that could be a viable tool for exploring cardiac diseases, including electrical and mechanical problems with the heart. In a released statement, Wayne E. Cascio, Associate Professor of Medicine at UNC, said, “The purpose of our study was to explore the possibility that one could take isolated heart cells and under proper conditions allow them to coalesce and attach to each other in a functional way, thereby creating an artificial tissue.”
He said the idea for the bioengineering tissue originated with a lecture given by Albert J. Banes, MD, UNC Professor of Orthopedics, who described his work on the development artificial tendons.
A Better Understanding of Rejection
Skin transplants between unrelated individuals are frequently rejected because new blood vessels that grow into the graft are actually viewed as nonself and destroyed by the immune system, according to researchers from the Cleveland Clinic, Case Western Reserve University School of Medicine, Cleveland, Ohio, the National Institute of Allergy and Infectious Disease in Bethesda, MD, and the Institut Curie in Paris, France, in the September, 2002 issue of Nature Immunology (Nature Imm. http://www.nature.com/cgi-taf/DynaPage.taf?file=/ni/journal/vaop/ncurrent/abs/ni831_fs.htmlls. Published online August 12, 2002.
The researchers used a mouse skin transplantation model and found that donor skin was rejected because the immune system attacks the newly formed blood vessels from the host that grow into the graft to nourish it. The vascular endothelial cells engulfed and displayed bits of the donor histocompatibility complex proteins. This alerted the immune system to the encroachment of the foreign bodies.
The researchers said the results might explain why skin is so difficult to transplant, but that the procedure may be applicable in other areas, such as the treatment of tumors.