Decades-old artificial heart valves still going strong
Two video clips of two Starr-Edwards artificial valves can be seen in action in this week’s online issue of the New England Journal of Medicine. The video was taken by doctors at the Montreal Heart Institute in Quebec during a cardiac catheterization procedure of a 67-year old woman. What is amazing is the fact that these valves, which are working properly and in tip top shape, were implanted 38 years ago [1].
In another case study, a 74-year old man had a double valve replacement with Smeloff-Cutter aortic and Starr-Edwards mitral prostheses 40 years ago. No additional surgery except a pacemaker implantation has been required during the last 4 decades. The latest ECG showed the valves to be intact [2].
Other follow-up studies indicate that the Starr-Edwards valve “represents a standard that still needs to be achieved by newer prostheses.” [3]
This is the lasting legacy of the retired engineer Lowell Edwards who, together with the surgeon Albert Starr, developed the valves almost 50 years ago. The first valve was successfully implanted in 1960. Edwards then founded Edwards Lifesciences, which today remains as one of the world’s leading manufacturer of medical devices. According to Nature News,, over a quarter of a million people received Starr-Edwards artificial valves until last year when the company stopped their manufacturing in favour of newer models.
Lowell Edwards was awarded the American Medical Association’s Layman’s Citation for Distinguished Service in 1982, only the 6th person so far to receive the honor. The citation described the innovator as
“a man of honor and courage whose inventive genius brought about the development of the artificial heart valve and whose long devotion to human welfare in the science of medicine has given new life and hope to victims of heart disease throughout the world.”
References:
1. Piazza N, Gregoire J. Images in clinical medicines. Starr-Edwards heart valves. N Engl J Med. 2008 May 22;358(21):e24.
2. Gödje OL et al. Thirty-year results of Starr-Edwards prostheses in the aortic and mitral position. Ann Thorac Surg. 1997 Mar;63(3):613-9.
3. Suezawa T et al. Forty-year survival with Smeloff-Cutter and Starr-Edwards prostheses. Ann Thorac Surg. 2008 Mar;85(3):e14-6.
The First Rapid Blood Test for MRSA is in the Market
In recent years, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection have been on the rise. This has especially become a problem in hospitals where MRSA infections have become synonymous to healthcare-associated infections.
S. aureus is a very common bacterial species that causes pimples and mild skin and wound infections. However, years of antibiotic use gave rise to strains which are resistant to the antibiotic methicillin as well as to other drugs. The MRSA strains can cause life-threatening conditions such as sepsis, infections of surgical sites, and pneumonia.
The US FDA has recently approved the first quick test to identify MRSA in the blood. Using molecular methods, the BD GeneOhm StaphSR Assay can detect genetic material from the common, less dangerous methicillin-sensitive S. aureus (MSSA) as well as the drug-resistant deadly MRSA strains [1, 2]
Early detection of MRSA infections is crucial in their treatment and management. Using standard diagnostic laboratory tests, it takes 2 days to identify MRSA in blood samples. With the new rapid test, results are available within 2 hours. This is especially good news to the public health community which had to deal with the rapid rise in the incidence of MRSA infections in hospitals and clinics. Immunocompromised patients are especially susceptible.
The BD GeneOhm StaphSR test is manufactured by BD Diagnostics, a subsidiary of BD of Franklin Lakes, N.J.
[1] FDA News, 2 Jan 2008. FDA Clears First Quick Test For Drug-Resistant Staph Infections.
Symposium on antiviral applications of RNAi
The European Science Foundation (ESF) and the European Molecular Biology Organization (EMBO) are organizing a symposium on “Antiviral Applications of RNA Interference” on 5 to 10 April 2008.
The symposium will take place in Sant Feliu de Guixols, Spain, located 120 km north of Barcelona.
RNA interference (RNAi) is a promising new technology with a great potential for use as an antiviral tool. The approach allows specific inhibition of gene expression either through the degradation of specific RNA molecules or hindering of transcription of certain genes. The first clinical trials to evaluate the efficacy and safety RNAi technologies have recently been started.
The symposium will mainly focus on human pathogenic viruses and “will be the first comprehensive meeting combining RNAi and antiviral research.”
“The meeting will cover the most recent progress in the field by 22 invited presentations of internationally renowned researchers, complemented by shorter contributed oral presentations of young scientists and by poster presentations.”
Nonclinical Studies: The Latest in Adult Stem Cell Research in Mice
In the latest issues of Nature and Science, two articles report on promising therapies using adult stem cells.
American and German researchers demonstrated that embryonic stem cells can mend post-infarction heart muscles without causing ventricular tachyarrhythmias. Following cardiomyocyte implantation, mice were protected against the induction of ventricular tachycardia. This was not evident when adult and bone marrow stem cells were used in the engraftment. The reason may be the fact that embryonic heart stem cells have a high degree of expression of the gap-junction protein connexin 43. Bone marrow stem cells engineered to express this protein afforded similar protection [1].
In another in vivo study, researchers successfully treated sickle-cell anemic mice using adult murine stem cell lines. The test mice were genetically-engineered to have a sickle-cell hemoglobin allelle, producing a “humanized sickle cell anemia mouse model.” The adult stem cells from these animals were reprogrammed to become pluripotent and their faulty allele was corrected by gene-specific targeting. Following transplantation of these reprogrammed and corrected cells, treated mice exhibited higher RBC counts and hemoglobin levels than control mice [2].
The results of these studies demonstrate potential cell-based therapies using adult stem cells.
[1] Roell, W. et al. Nature 450, 819-824 (6 December 2007)
[2] Hanna, J. et al. Science doi:10.1126/science.1152092 (6 December 2007)
Limits on MRI Use in the EU postponed
The EU decided to postpone introducing a law regulating workers’ exposure to electromagnetic fields [1]. The decision is based on the fact that such as legislation would place serious limits on the use of magnetic resonance imaging (MRIs).
Directive 2004/40/EC was aimed to protect workers against the occupational hazard of electromagnetic field exposure and was to take effect in April 2008 [2]. However, the high occupational limit values set by the directive would inadvertently put a ban on the use of MRI in diagnostic medicine.
“MRI is currently the leading technique for detecting brain tumours and many other serious conditions. It allows doctors to help 8 million patients each year…[the EC] is well aware of the enormous benefits of MRI and of its immense value for public health.” [1]
Other international agencies such as the International Commission on Non-Ionising Radiation Protection (ICNIRP) and the World Health Organisation (WHO) are looking into revising the current occupational limit values for electromagnetic fields [1]. The EU will probably introduce a revised directive based on similar limits in 2012.
In the meantime, the EU is pushing for more research in this field. It is funding projects under the 7th Framework Programme for Research to explore hybrid imaging systems such as MRI/PET and MRI/Ultrasound [1].
Sources:
[1] EU Press Release 26/10/2007. Commission to postpone and amend electromagnetic fields legislation to protect MRI Reference: IP/07/1610.
[2] Directive 2004/40/EC of the European Parliament and of the Council of 29 April 2004. Official Journal of the European Union L 159.