Human Health and Science » Vascular surgery

‘Fountain of youth’ technique rejuvenates aging stem cells

Wed, 28 Nov 2012 02:23:16 +0000

‘Fountain of youth’ technique rejuvenates aging stem cells : Human Health & Science

ScienceDaily (Nov. 27, 2012) A new method of growing cardiac tissue is teaching old stem cells new tricks. The discovery, which transforms aged stem cells into cells that function like much younger ones, may one day enable scientists to grow cardiac patches for damaged or diseased hearts from a patient’s own stem cells — no matter what age the patient — while avoiding the threat of rejection.

Stem cell therapies involving donated bone marrow stem cells run the risk of patient rejection in a portion of the population, argues Milica Radisic, Canada Research Chair in Functional Cardiovascular Tissue Engineering at the Institute of Biomaterials and Biomedical Engineering (IBBME) and Associate Professor in the Department of Chemical Engineering and Applied Chemistry at the University of Toronto.

One method of avoiding the risk of rejection has been to use cells derived from a patient’s own body. But until now, clinical trials of this kind of therapy using elderly patients’ own cells have not been a viable option, since aged cells tend not to function as well as cells from young patients.

“If you want to treat these people with their own cells, how do you do this?”

It’s a problem that Radisic and her co-researcher, Dr. Ren-Ke Li, think they might have an answer for: by creating the conditions for a ‘fountain of youth’ reaction within a tissue culture.

Li holds the Canada Research Chair in Cardiac Regeneration and is a Professor in the Division of Cardiovascular Surgery, cross-appointed to IBBME. He is also a Senior Scientist at the Toronto General Research Institute.

Radisic and Li first create a “micro-environment” that allows heart tissue to grow, with stem cells donated from elderly patients at the Toronto General Hospital.

The cell cultures are then infused with a combination of growth factors — common factors that cause blood vessel growth and cell proliferation — positioned in such a way within the porous scaffolding that the cells are able to be stimulated by these factors.

Dr. Li and his team then tracked the molecular changes in the tissue patch cells. “We saw certain aging factors turned off,” states Li, citing the levels of two molecules in particular, p16 and RGN, which effectively turned back the clock in the cells, returning them to robust and healthy states.

“It’s very exciting research,” says Radisic, who was named one of the top innovators under 35 by MIT in 2008 and winner of the 2012 Young Engineers Canada award.

Li and Radisic hope to continue their goal to create the most effective environment in which cells from older patients can be given new life. “We can create much better tissues which can then be used to repair defects such as aneurysms,” Li says, as well as repairing damage caused by heart attacks.

The study was recently released in the Journal of the American College of Cardiology, the top journal in the field of cardiovascular medicine.

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The above story is reprinted from materials provided by University of Toronto, via EurekAlert!, a service of AAAS.

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Journal Reference:

Kai Kang, Lu Sun, Yun Xiao, Shu-Hong Li, Jun Wu, Jian Guo, Shu-Ling Jiang, Lei Yang, Terrence M. Yau, Richard D. Weisel, Milica Radisic, Ren-Ke Li. Aged Human Cells Rejuvenated by Cytokine Enhancement of Biomaterials for Surgical Ventricular Restoration. Journal of the American College of Cardiology, 2012; 60 (21): 2237 DOI: 10.1016/j.jacc.2012.08.985

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Surgeons pilot expandable prosthetic valves for congenital heart disease

Wed, 03 Oct 2012 13:43:51 +0000

Surgeons pilot expandable prosthetic valves for congenital heart disease : Human Health & Science

ScienceDaily (Oct. 3, 2012) Surgeons at Boston Children’s Hospital have successfully implanted a modified version of a expandable prosthetic heart valve in several children with mitral valve disease. Unlike traditional prosthetic valves that have a fixed diameter, the expandable valve can be enlarged as a child grows, thus potentially avoiding the repeat valve replacement surgeries that are commonly required in a growing child. The new paradigm of expandable mitral valve replacement has potential to revolutionize care for infants and children with complex mitral valve disease.

The surgical team, led by Sitaram M. Emani, MD, and Pedro J. del Nido, MD, of the Department of Cardiac Surgery at Boston Children’s, summarized their outcomes with two patients in the October 2012 edition of Annals of Thoracic Surgery.

The care of patients with disease of the mitral valve — which controls the flow of freshly oxygenated blood from the heart’s left atrium to its left ventricle — can be very complicated. If a child needs a mitral valve replacement, there are only a limited number of options available, all of which have one limitation in common: they have a fixed diameter and cannot grow with a child.

Thus, children who undergo mitral valve replacement must undergo additional future surgeries to have new, larger valves implanted as they outgrow their replacements. However, once implanted, fixed-diameter valves restrict growth of the “annulus” — the backbone — of the mitral valve. This limits the size of the valves that can be implanted in subsequent repeat replacement operations.

“We prefer to repair a child’s mitral valve if we can, but patients who are not candidates for repair due to severe deformity of the valve must undergo replacement,” said Emani, a pediatric cardiac surgeon who specializes in cardiovascular surgery for newborns and children with complex congenital heart disease. “One challenge that cardiac surgeons have not been able to overcome is the lack of a replacement valve small enough for mitral valve replacement in newborns, which forces us to perform suboptimal surgical repairs that mandate repeat operations until the child is old enough to get our smallest replacement valve. In addition, children often outgrow a prosthetic valve within months to years after implantation, requiring multiple replacements over time.”

To provide a novel and more permanent option for children needing mitral valve replacement, Emani and his colleagues developed and surgically implanted a modified version of an expandable prosthetic valve available from Medtronic, Inc., called the Melody valve, in two infants with congenital heart disease. The Melody is approved by the US Food and Drug Administration for replacement of the heart’s pulmonary valve, which controls blood flow from the heart to the lungs; this is the first instance of its use as a mitral valve replacement.

“We wanted to find a solution that would allow us to expand a valve as a child grows and avoid taking them back into the operating room,” Emani explained. “This modified valve can be expanded within a patient via cardiac catheterization, potentially allowing us to leave the valve in place until a patient reaches adulthood and reducing the number of operations and the risk of lung swelling related to valve leakage. It opens up the opportunity to carry out mitral valve replacement in more children and at an earlier time point than has historically been possible.”

One of the patients described in the paper, a nine-month-old baby, had a mitral valve that was deemed irreparable and which Emani’s team replaced with a modified Melody valve. Several months later, the team was able to successfully expand the replacement in a cardiac catheterization procedure. When compared to a major repeat chest operation, a cardiac catheterization — which involves insertion of a fine catheter into the heart through a vessel in the groin- is much less invasive and requires less recovery time.

“Since submitting this paper, we’ve carried the procedure out on an additional three patients, all of whom are doing well,” Emani noted. “Two of our patients have already undergone their first growth-related valve dilations, and in both, the procedure went better than expected.

“The others have gone almost a year without the need for additional surgeries, which is remarkable given the level of surgical care small children with mitral valve disease usually need,” he continued.

“This work illustrates perfectly the attitude of innovation that runs deep within our cardiac surgery team,” said del Nido, who is the chief of cardiac surgery at Boston Children’s. “We are striving to bring about better options in every aspect of pediatric cardiac care.

“Valve care is particularly complex, requiring a team approach involving providers from imaging, surgery, intensive care and other medical subspecialties to provide the best care,” del Nido added. “It’s rare for single institutions to have this combination of expertise necessary to bring a novel cardiac technology to pediatric patients.”

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The above story is reprinted from materials provided by Boston Children’s Hospital.

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Journal Reference:

Ibrahim Abdullah, Francisco Boye Ramirez, Doff B. McElhinney, James E. Lock, Pedro J. del Nido, Sitaram Emani. Modification of a Stented Bovine Jugular Vein Conduit (Melody Valve) for Surgical Mitral Valve Replacement. The Annals of Thoracic Surgery, 2012; 94 (4): e97 DOI: 10.1016/j.athoracsur.2012.02.101

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Novel surgery removes rare tumor, rebuilds face and jaw

Sat, 08 Sep 2012 05:29:50 +0000

Novel surgery removes rare tumor, rebuilds face and jaw : Human Health & Science

ScienceDaily (Sep. 7, 2012) Using a novel surgical approach, it’s possible to rebuild a functional lower jaw and mouth, and preserve a patient’s ability to eat and speak after removing an invasive facial tumor, according to a new report from Henry Ford Hospital in Detroit.

This case study not only documents a successful surgical technique to create a fully functional lower jaw, but also reports the rare occurrence of a bone cancer (osteosarcoma) that spread from the patient’s right femur to his jaw bone.

Most commonly, osteosarcoma is found in the long bones of the leg and does not spread to other parts of the body.

“The bone tumor involved nearly all of his jaw bone, lower lip, chin, neck skin, tongue and both cheeks, approximately the lower third of the face and upper half of his neck,” says senior study author Tamer A. Ghanem, M.D., Ph.D., director of the Head and Neck Oncology & Microvascular Surgery Division and division head of the Department of Otolaryngology-Head and Neck Surgery at Henry Ford Hospital.

“We had to think outside the box to not only safely remove the tumor, but to allow for optimum functional outcome.”

Dr. Ghanem will present this unique case study this weekend at the poster session for the American Academy of Facial Plastic and Reconstructive Surgery annual meeting in Washington, D.C.

The case is centered on a 21-year-old African American male with a history of osteosarcoma, the eighth most common childhood cancer. It affects 5 million patients under the age 20 and about 500 adults ages 15-30 each year in the U.S.

The patient’s osteosarcoma spread to his jaw bone about three years after the initial diagnosis. The facial tumor soon grew to nearly 10 lbs. of tissue and bone, making it difficult for him to speak and eat. The patient required a feeding tube.

Only three months after the surgery, the patient was able to talk and eat without assistance.

Prior to coming to Henry Ford Hospital, the patient underwent multiple treatments including mandible resection, radiation, chemotherapy and cryosurgery at another institution. All treatments were unsuccessful.

Dr. Ghanem and his colleague Francis Hall, M.D., devised a plan that would not only surgically remove the tumor and oral tongue, but rebuild the lower third of the patient’s face — all during a 20-hour surgical procedure.

The surgeons performed a near total mandibulectomy (surgical removal of the bone from the lower jaw), and removal of the tongue, mucous membrane from the inside of both cheeks and lower lip.

Dr. Ghanem performed the complex reconstruction of the face and jaw using dual microvascular free flaps from the fibula and shoulder areas.

“The reconstruction involved bone and skin transplanted from the patient’s left leg, and a tissue complex from his shoulder blade area with its feeding blood supply compromised of multiple islands of skin and muscles to reconstruct all of the tissues,” says Dr. Ghanem.

The subscapular free flap (skin and muscle from the shoulder) is a versatile donor system that offers distinct advantages in the reconstruction of head and neck defects. The shoulder’s soft tissue offers mobility, while this area also has a diverse range of skin, bone and muscle available for use in reconstruction of massive facial defects.

Along with Dr. Ghanem and Dr. Hall, Henry Ford Hospital co-authors are Robert Deeb, M.D., and Linda Hsu.

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Study questions technique to repair ruptured abdominal aortic aneurysms

Mon, 27 Aug 2012 23:38:30 +0000

Study questions technique to repair ruptured abdominal aortic aneurysms : Human Health & Science

ScienceDaily (Aug. 27, 2012) A new study raises a cautionary note about the increasing use of a minimally invasive procedure to repair ruptured abdominal aortic aneurysms, according to vascular surgeon Dr. Jae Sung Cho of Loyola University Medical Center.

A ruptured abdominal aortic aneurysm (AAA) causes massive internal bleeding that requires immediate emergency surgery to save the patient.

The rupture can be repaired either with an open surgery or with a newer, less-invasive endovascular technique that involves the use of a catheter.

At first glance, the endovascular technique would appear to be a better option because it is minimally invasive and has lower complication rates. It’s being increasingly used to repair ruptured AAAs.

But a study in the Journal of Vascular Surgery, published online ahead of print, found that the endovascular technique does not conclusively improve survival.

In the retrospective study, Cho and colleagues compared 37 patients with ruptured AAAs who underwent emergency endovascular surgery and 241 patients with ruptured AAAs who underwent open surgery. The groups were matched by sex, age, surgeon experience, patient condition and other factors. The average age was 74.9 in the endovascular group and 75.6 in the open surgery group. The endovascular group’s probability of survival was 50 percent after the first year and 42 percent after three years. By comparison, the open surgery group’s probability of surviving was 54 percent after the first year and 47 percent after three years.

The overall complication rate was 66 percent in the open surgery group and 54 percent in the endovascular surgery group, but this difference was not statistically significant.

Cho and colleagues wrote that preferential use of the endovascular technique “should be deferred until results of prospective, randomized trials are available and predictive factors for its success are identified. Some patients may be harmed by indiscriminate insistence on (the endovascular technique).”

The study was conducted at the University of Pittsburgh Medical Center, where Cho practiced before recently joining Loyola as chief of vascular surgery. Cho is a professor in the Department of Surgery, Division of Vascular Surgery and Endovascular Therapy at Loyola University Chicago Stritch School of Medicine.

An AAA is a bulge in the large blood vessel that supplies blood to the abdomen and legs. Risk factors for AAAs include smoking, high blood pressure, high cholesterol, male gender, emphysema, genetic factors, obesity and increasing age. The bulge typically develops slowly over many years. The larger the aneurysm, the more likely it is to rupture and cause massive bleeding. About 15,000 people per year die from ruptured AAAs. Many die before getting to the hospital. But certain patients can be saved if they make it to the hospital on time.

In the open surgery technique, the surgeon makes a large incision and opens up the abdomen. The surgeon clamps the aorta to stop the bleeding, then replaces or bypasses the ruptured section with an artificial blood vessel.

In the endovascular technique, the surgeon inserts a catheter in a groin artery and guides the catheter through blood vessels to the site of the burst aneurysm. The surgeon deploys a device called a stent graft. The device, shaped like an inverted Y, is made of GoreTex® or Dacron®, and is supported by metal webbing. After it is deployed from the catheter, the stent graft expands outward to the walls of the artery. This allows blood to flow safely through the stent graft, rather than gushing into the abdominal cavity.

While much less invasive than open surgery, the endovascular technique has drawbacks, Cho said. There can be more internal bleeding because of a delay in clamping the aorta. And even after a successful stent graft placement, there may be ongoing blood loss. Also, the large amount of blood left in the abdomen can compress other organs and the chest cavity and may require surgery to remove the blood.

The endovascular technique also can put a significant strain on hospital resources. The hospital must stock various sizes of stent grafts, which cost at least $12,000 each. And skilled endovascular, radiologic and nursing teams must be available around the clock. “It is not pragmatic to undertake such systemic and systematic changes in the absence of clear evidence of (the endovascular technique’s) superiority,” Cho and colleagues wrote.

Cho is a nationally known expert in the treatment of AAAs and other vascular diseases. He said he uses his best judgment to decide whether a particular patient should undergo endovascular surgery or open surgery.

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The above story is reprinted from materials provided by Loyola University Health System.

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Naveed Saqib, Sun Cheol Park, Taeyoung Park, Robert Y. Rhee, Rabih A. Chaer, Michel S. Makaroun, Jae-Sung Cho. Endovascular repair of ruptured abdominal aortic aneurysm does not confer survival benefits over open repair. Journal of Vascular Surgery, 2012; DOI: 10.1016/j.jvs.2012.01.081

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Study questions technique to repair ruptured abdominal aortic aneurysms

Mon, 27 Aug 2012 23:34:18 +0000

Study questions technique to repair ruptured abdominal aortic aneurysms : Human Health & Science

A ruptured abdominal aortic aneurysm (AAA) causes massive internal bleeding that requires immediate emergency surgery to save the patient.

The rupture can be repaired either with an open surgery or with a newer, less-invasive endovascular technique that involves the use of a catheter.

But a study in the Journal of Vascular Surgery, published online ahead of print, found that the endovascular technique does not conclusively improve survival.

The overall complication rate was 66 percent in the open surgery group and 54 percent in the endovascular surgery group, but this difference was not statistically significant.

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The above story is reprinted from materials provided by Loyola University Health System.

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Journal Reference:

Naveed Saqib, Sun Cheol Park, Taeyoung Park, Robert Y. Rhee, Rabih A. Chaer, Michel S. Makaroun, Jae-Sung Cho. Endovascular repair of ruptured abdominal aortic aneurysm does not confer survival benefits over open repair. Journal of Vascular Surgery, 2012; DOI: 10.1016/j.jvs.2012.01.081

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

New aortic valve replacement procedure

Wed, 04 Jan 2012 12:53:30 +0000

New aortic valve replacement procedure : Human Health & Science

ScienceDaily (Jan. 3, 2012) Some individuals with severe aortic stenosis — also known as narrowing of the aortic valve in the heart — who are not well enough to undergo open heart surgery have a new treatment option thanks to a groundbreaking procedure now available in Kentucky from UofL physicians at Jewish Hospital.

A team that included University of Louisville cardiologists Michael Flaherty, M.D, Ph.D., Naresh Solankhi, M.D., and UofL cardiothoracic surgeon Matthew Williams, M.D., performed the first transcatheter aortic-valve replacement (TAVR) procedure on a 47-year-old male patient on Dec. 21, 2011.

During the procedure a biological valve was inserted through a catheter and implanted within a diseased aortic valve. The procedure allows for valve replacement without traditional open-heart surgery and while the heart is beating, therefore avoiding cardiopulmonary bypass.

It is the only valve replacement option for patients with severe aortic stenosis who are not well enough to undergo traditional open-heart surgery. Most patients will avoid any surgery in their chest.

“For patients who qualify, the TAVR procedure is often their last hope for treatment of their heart disease,” said Flaherty, who is assistant professor of medicine, physiology and biophysics and director of research-interventional cardiology in the Department of Medicine at the University of Louisville. “It’s a unique procedure, and we are once again proud to be on the cutting edge of heart care in the region.”

During the TAVR procedure, a cardiologist and cardiothoracic surgeon work together to implant the new heart valve, called the Edwards SAPIEN valve, which is made from cow tissue and developed by Edwards Lifesciences.

The valve is inserted into the body through a small cut in the leg. Once delivered to the site of the patient’s diseased valve, the Edwards SAPIEN valve is expanded with a balloon and immediately functions in place of the patient’s valve.

Jewish Hospital is one of 29 sites in the United States where researchers are now studying the Edwards SAPIEN transcatheter aortic heart valve and the next-generation Edwards SAPIEN XT valve as part of an ongoing national clinical trial called the PARTNER II Trial. The Edwards SAPIEN valve — studied in the first PARTNER Trial and used in Europe since 2007 — recently received FDA approval for the treatment of inoperable patients in the United States. This is the first U.S. commercial approval for a transcatheter device enabling aortic valve replacement without the need for open-heart surgery.

“The availability of the TAVR procedure marks a major milestone in the treatment of valve-related heart disease,” said Williams, who practices with University Cardiothoracic Surgical Associates and is assistant professor of thoracic and cardiovascular surgery in the Department of Surgery at UofL. “It gives us another tool to help take care of people. Older folks, who would prefer to avoid surgery if they can, will be the patients who will most often benefit.”

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New aortic valve replacement procedure

Wed, 04 Jan 2012 12:46:18 +0000

New aortic valve replacement procedure : Human Health & Science

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Common gene variant associated with aortic dissection: Study reveals risk factor that doubles chance of developing silent killer

Sun, 11 Sep 2011 18:52:52 +0000

Common gene variant associated with aortic dissection: Study reveals risk factor that doubles chance of developing silent killer : Human Health & Science

ScienceDaily (Sep. 11, 2011) Richard Holbrooke, John Ritter, Lucille Ball, Jonathan Larson and Great Britain’s King George II were all taken by the same silent killer: an acute aortic dissection.

Now, scientists led by researchers at The University of Texas Health Science Center at Houston (UTHealth) and Baylor College of Medicine (BCM) have found an association with a common genetic variant in the population that predisposes people to acute dissections and can approximately double a person’s chances of having the disease.

An aortic aneurysm is an enlargement or ballooning of the aorta in the segment where it comes out of the heart (thoracic aortic aneurysm). The natural history of a thoracic aortic aneurysm is to enlarge without symptoms over time, leading to instability of the aorta and ultimately an acute aortic dissection. The dissection is a tear in the aorta that allows blood to flow within its layers. It is a life-threatening event, with up to 40 percent of patients dying suddenly.

Although the average age of a person who suffers an aortic dissection is early 60s, the disease can strike at any age. Since the majority of individuals have an aortic aneurysm prior to dissection, identification of these aneurysms is critical since the aneurysm can be surgically repaired to prevent the aortic dissection, which typically occurs when the diameter of the aneurysm reaches twice that of the normal aorta. Therefore it is important to know who is at risk for this disorder.

The results of the research are published in the Sept. 11, 2011 advance online issue of Nature Genetics. Senior author is Dianna M. Milewicz, M.D., Ph.D., professor and the President George H.W. Bush Chair in Cardiovascular Research at The University of Texas Medical School at Houston, part of UTHealth.

“This is the first time we’ve found an association with a common genetic variant in the population that predisposes people to thoracic aortic aneurysms that cause acute aortic dissections. This variant in the DNA is on chromosome 15 (15q21.1) and involves a gene called FBN1. We already know that mutations in this gene cause Marfan syndrome, which is a genetic syndrome that strongly predisposes individuals to aortic dissections but also causes people to grow tall and have weak eyes,” said Milewicz, who is also director of the Division of Medical Genetics at the UTHealth Medical School and heads the UTHealth John Ritter Research Program in Aortic and Vascular Diseases. “Although patients with aortic dissection in our study did not have Marfan syndrome, this study suggests that the same pathways are involved in causing aortic dissections in patients with and without Marfan syndrome.”

Milewicz said the research has implications for using drugs to treat patients to prevent aortic aneurysms from even forming, such as losartan, which is now being tested in clinical trials for people with Marfan syndrome. “Whether they have Marfan or the common variant in FBN1, it may be the same pathway and we may be able to treat these patients the same way. That means that what we learn in treating patients with Marfan syndrome has implications for this larger group of individuals with thoracic aortic disease,” she said.

“Over the past two decades, there has been remarkable progress in understanding the causes of aortic aneurysms and dissections in patients with inherited disorders, particularly Marfan syndrome. However, up to 80 percent of patients with thoracic aortic aneurysms and dissections do not have a known inherited cause, and the genetic factors that impact susceptibility to aortic disease in these patients are poorly understood,” said the study’s first author Scott A. LeMaire, M.D., professor of surgery and director of research in the Division of Cardiothoracic Surgery at BCM and surgeon at the Texas Heart Institute at St. Luke’s Episcopal Hospital. “This gap in our understanding of ‘sporadic’ disease motivated us to conduct this study, which would not have been possible without the tremendous efforts of a large team of dedicated collaborators.”

The study examined more than 1,300 patients who had sporadic thoracic aortic disease, meaning they did not have a known family genetic history or genetic syndrome associated with the disease. The patients came from the Memorial Hermann Heart & Vascular Institute, the Texas Heart Institute and Harvard Medical School, as well as from the National Institutes of Health GenTAC program, which includes the Perelman School of Medicine at the University of Pennsylvania, Johns Hopkins University School of Medicine, Weill Cornell Medical College of Cornell University and Oregon Health and Science University.

The discovery was made possible by a grant from the NIH that funded the Specialized Center for Clinically Oriented Research in Aortic Diseases, a multi-institutional collaboration in the Texas Medical Center. The title of the article is “Genome-wide association study identifies a susceptibility locus for thoracic aortic aneurysms and aortic dissections spanning FBN1 at 15q21.1.” Merry-Lynn N. McDonald, Ph.D., at BCM; and Dong-chuan Guo, Ph.D., assistant professor of internal medicine at UTHealth, contributed equally along with LeMaire as co-first authors on the article.

Other UTHealth co-authors include Charles C. Miller, III, Ph.D., professor of cardiothoracic and vascular surgery; Ralph J. Johnson, Ph.D., assistant professor of internal medicine; Hazim Safi, M.D., professor and chair of the Department of Cardiothoracic and Vascular Surgery; and Anthony L. Estrera, M.D., professor of cardiothoracic and vascular surgery.

BCM co-investigators include Suzanne M. Leal, Ph.D., professor of molecular and human genetics; John W. Belmont, M.D., Ph.D., professor of molecular and human genetics; Ludivine Russell, M.S., cardiothoracic surgery research coordinator; Mir Reza Bekheirnia, M.D., clinical fellow in the Department of Molecular and Human Genetics; Luis M. Franco, M.D., assistant professor of molecular and human genetics; Mary Nguyen, B.S., cardiothoracic surgery laboratory technician; Molly Bray, Ph.D., associate professor of pediatrics; and Joseph S. Coselli, M.D., professor and chief of the Division of Cardiothoracic Surgery. Harvard Medical School co-investigators are Simon C. Body, M.B., Ch.B., M.P.H., associate professor of anesthesia; Christine Seidman, M.D., professor of genetics and medicine; Jonathan G. Seidman, Ph.D., professor of genetics; and Eric M. Isselbacher, M.D., associate professor medicine.

Other co-investigators are Reed E. Pyeritz, M.D., Ph.D., Perelman School of Medicine at the University of Pennsylvania; Joseph E. Bavaria, M.D., Perelman School of Medicine at the University of Pennsylvania; Richard Devereux, M.D., Weill Cornell Medical College; Cheryl Maslen, Ph.D., Oregon Health and Science University; Kathryn W. Holmes, Johns Hopkins University School of Medicine, M.D., M.P.H; and Kim Eagle, M.D., University of Michigan Medical School.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Texas Health Science Center at Houston, via EurekAlert!, a service of AAAS.

Journal Reference:

Scott A LeMaire, Merry-Lynn N McDonald, Dong-chuan Guo, Ludivine Russell, Charles C Miller, Ralph J Johnson, Mir Reza Bekheirnia, Luis M Franco, Mary Nguyen, Reed E Pyeritz, Joseph E Bavaria, Richard Devereux, Cheryl Maslen, Kathryn W Holmes, Kim Eagle, Simon C Body, Christine Seidman, J G Seidman, Eric M Isselbacher, Molly Bray, Joseph S Coselli, Anthony L Estrera, Hazim J Safi, John W Belmont, Suzanne M Leal, Dianna M Milewicz. Genome-wide association study identifies a susceptibility locus for thoracic aortic aneurysms and aortic dissections spanning FBN1 at 15q21.1. Nature Genetics, 2011; DOI: 10.1038/ng.934

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Sutureless method for joining blood vessels invented

Sun, 28 Aug 2011 18:10:10 +0000

Sutureless method for joining blood vessels invented : Human Health & Science

ScienceDaily (Aug. 28, 2011) Reconnecting severed blood vessels is mostly done the same way today — with sutures — as it was 100 years ago, when the French surgeon Alexis Carrel won a Nobel Prize for advancing the technique. Now, a team of researchers at the Stanford University School of Medicine has developed a sutureless method that appears to be a faster, safer and easier alternative.

In animal studies, a team led by Stanford microsurgeon Geoffrey Gurtner, MD, used a poloxamer gel and bioadhesive rather than a needle and thread to join together blood vessels, a procedure called vascular anastomosis. Results of the research will be published online Aug. 28 in Nature Medicine. Lead authors of the study were Stanford postdoctoral scholar Edward Chang, MD, and surgery resident Michael Galvez, MD.

The big drawback of sutures is that they are difficult to use on blood vessels less than 1 millimeter wide. Gurtner began thinking about alternatives to sutures about a decade ago. “Back in 2002, I was chief of microsurgery at Bellevue in New York City, and we had an infant — 10 to 12 months old — who had a finger amputated by the spinning wheel of an indoor exercise bike,” said Gurtner, senior author of the study and professor of surgery. “We struggled with reattaching the digit because the blood vessels were so small — maybe half a millimeter. The surgery took more than five hours, and at the end we were only able to get in three sutures.

“Everything turned out OK in that case,” he continued. “But what struck me was how the whole paradigm of sewing with a needle and thread kind of falls apart at that level of smallness.”

Sutures are troublesome in other ways, too. They can lead to complications, such as intimal hyperplasia, in which cells respond to the trauma of the needle and thread by proliferating on the inside wall of the blood vessel, causing it to narrow at that point. This increases the risk of a blood clot getting stuck and obstructing blood flow. In addition, sutures may trigger an immune response, leading to inflamed tissue that also increases the risk of a blockage.

The new method could sidestep these problems. “Ultimately, this has the potential to improve patient care by decreasing amputations, strokes and heart attacks while reducing health-care costs,” the authors write in the study.

Earlier in his career, as Gurtner contemplated a better way of joining together blood vessels, he considered whether ice could be used to fill the lumen, the inner space of the blood vessel, to keep both ends open to their full diameter long enough to glue them together. Not feasible, he concluded. “Water turns to ice quite slowly and you would have to drop the temperature of the surgical site a lot — from 98.6 degrees to 32 degrees Fahrenheit,” he said.

Shortly after arriving at Stanford in 2005, Gurtner approached fellow faculty member Gerald Fuller, PhD, professor of chemical engineering and the Fletcher Jones II Professor in the School of Engineering, about whether he knew of a substance that could be turned easily from a liquid to a solid and back to a liquid again, and that would also be safe to use in vascular surgery. Fuller immediately suggested a Food and Drug Administration-approved thermoreversible poloxamer called Poloxamer 407. It is constructed of polymer blocks whose properties can be reversed by heating.

Fuller teamed up with Jayakumar Rajadas, PhD, director of the Stanford Biomaterials and Advanced Drug Delivery Laboratory, to modify the poloxamer so that it would become solid and elastic when heated above body temperature but dissolve harmlessly into the bloodstream when cooled. The poloxamer then was used to distend both openings of a severed blood vessel, allowing researchers to glue them together precisely.

The researchers used a simple halogen lamp to heat the gel. In tests on animals, the technique was found to be five times faster than the traditional hand-sewn method, according to the study. It also resulted in considerably less inflammation and scarring after two years. The method even worked on extremely slim blood vessels — those only 0.2 mm wide — which would have been too tiny and delicate for sutures. “That’s where it really shines,” Gurtner said.

Dermabond, a surgical sealant, was used to attach the ends of the blood vessels together.

Poloxamers have been used before as a vehicle for delivering drugs, including chemotherapeutics, vaccines and anti-viral therapies. Researchers have used Poloxamer 407 to occlude blood vessels in experimental animals for the purpose of evaluating the gel’s safety and efficacy in so-called “beating heart surgery,” in which certain vessels need to be temporarily blocked to improve visibility for the surgeons performing a coronary artery bypass.

Although other sutureless methods have been developed, they generally have not produced better outcomes, the authors said. “Often, the use of microclips, staples or magnets is itself traumatic to blood vessels leading to failure rates comparable to or higher than sutured anastomoses,” they wrote.

“This is a novel approach to anastomosis that could play a valuable role in microvascular surgery,” said Frank Sellke, MD, chief of cardiothoracic surgery at Brown University Medical Center and associate editor of the Journal of Thoracic and Cardiovascular Surgery, who was not involved in the study. “But it really needs to show that it holds up in clinical trials.”

The authors say further testing on large animals is needed before human trials can begin, but they note that all of the components used in the technique are already approved by the FDA. “This technology has the potential to progress rapidly from the ‘bench to bedside,’” they write.

Gurtner said he believes the new technique could satisfy a huge unmet need and prove especially useful in minimally invasive surgeries, in which manipulating sutures takes on a whole new level of difficulty.

Michael Longaker, MD, the Deane P. and Louise Mitchell Professor in the School of Medicine and a co-author of the study, called the technique a “potential game-changer.”

“When you’re bringing together hollow tubes, whether they’re large structures, like the colon or the aorta, or a small structure, like a vein in the finger of a child, you’re always worried about lining them up directly and effectively sealing them,” Longaker said. “The technique that Dr. Gurtner has pioneered could allow surgeons to perform anastomosis more quickly and with improved precision.”

He continued: “Coming up with this solution was the result of the classic Stanford model of bringing together researchers from a variety of disciplines.”

Other Stanford co-authors of the study were postdoctoral scholars Jason Glotzbach, MD, Kristin-Maria Sommer, PhD, Oscar Abilez, MD, PhD, and Cynthia Hamou, MD; medical student Samyra El-ftesi; and technician Travis Rappleye.

The work was supported by a Stanford Bio-X Interdisciplinary Initiatives Research Award and the Oak Foundation. Stanford University has patented the technology.

Gurtner and Longaker are also members of the Stanford Cancer Institute.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford University Medical Center, via EurekAlert!, a service of AAAS.

Journal Reference:

Edward I Chang, Michael G Galvez, Jason P Glotzbach, Cynthia D Hamou, Samyra El-ftesi, C Travis Rappleye, Kristin-Maria Sommer, Jayakumar Rajadas, Oscar J Abilez, Gerald G Fuller, Michael T Longaker, Geoffrey C Gurtner. Vascular anastomosis using controlled phase transitions in poloxamer gels. Nature Medicine, 2011; DOI: 10.1038/nm.2424

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Atherosclerosis is not limited to the heart

Fri, 26 Aug 2011 15:15:15 +0000

Atherosclerosis is not limited to the heart : Human Health & Science

ScienceDaily (Aug. 26, 2011) For cardiologists, coronary artery disease is the most important presentation of atherosclerosis. Patients with coronary artery disease may also have symptomatic or asymptomatic atherosclerosis in other vascular areas (peripheral artery disease).

The presence of atherosclerotic disease at one vascular site increases the likelihood of the disease at another site. In the elderly, who constitute the dominant part of patient population, the overlap of coronary artery disease, cerebrovascular disease and lower extremity artery disease is particularly high. In consequence, increasing numbers of patients with heart disease need to be assessed for problems in other vascular sites. On the other hand, a substantial proportion of patients with peripheral artery diseases will die from coronary artery disease.

The Guidelines on peripheral artery disease (PAD) are the first document produced by the ESC to address all aspects — with the exception of the aorta — of peripheral atherosclerotic disease, including disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteries. They are the result of close collaboration between physicians from many different areas of expertise: cardiology, neurology, radiology, vascular surgery, and vascular medicine.

The document covers general issues such as epidemiology, risk factors, diagnostic approaches, and general rules for treatment. The detailed clinical presentations are then discussed in specific sections for each vascular site. Particular emphasis is placed on multisite artery disease, such as patients with coronary artery disease and disease in another vascular bed. The document ends with a list of significant gaps in evidence, which will hopefully stimulate new research.

The section on treatment modalities in patients with carotid artery disease covers medical therapy, surgery, and endovascular techniques. The Guidelines clearly differentiate management of symptomatic and asymptomatic patients. In patients with symptomatic disease, neurological assessment and appropriate treatment should be proposed as soon as possible after the index event.

The document also addresses clinical presentation, diagnostic modalities, prognosis and treatment in patients with upper extremity, mesenteric and renal artery disease.

The Guidelines extensively cover diagnosis (with an emphasis on the importance of the ankle-brachial index) and treatment, with endovascular or surgical techniques, in patients with lower extremity artery disease (LEAD), differentiating between those suffering from claudication and those with critical limb ischaemia. The document emphasises the importance of an adequate balance between supervised exercise and best medical therapy as compared to revascularization in patients with LEAD, taking into account the level of disability and the localisation of disease.

A very important section of these Guidelines concerns the management of patients with multisite artery disease. Indeed, although patients with multisite artery disease are encountered regularly in clinical practice, no randomized trials have been designed to compare different treatment strategies. From a clinical perspective, this document emphasises the need for an increased awareness of the possibility of atherosclerotic disease occurring at sites other than the presenting one. The document also emphasises that, when dealing with a patient with multisite artery disease, the physician must focus attention not only on lesion sites and inherent technical difficulties related to specific treatment options, but also on the overall clinical status of the patient, taking into account the presence of all cardiovascular risk factors and comorbidities.

In conclusion, the new ESC Guidelines on the diagnosis and treatment of peripheral artery disease will help physicians manage most common aspects of PAD from a variety of complex clinical scenarios encountered in clinical practice. These Guidelines emphasise that the management of patients with PAD should always be decided after multidisciplinary discussion, also including specialists beyond the area of cardiovascular medicine, for example neurologists or nephrologists. This was also the way in which current Guidelines were created.

The Guidelines will be formally introduced at a special session of the ESC Congress 2011 in Paris on 29th August.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by European Society of Cardiology (ESC).

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.