{"69241":{"#nid":"69241","#data":{"type":"news","title":"Study of Tricuspid Valve Mechanics Uncovers Causes for Leakage","body":[{"value":"\u003Cp\u003EA new study into the causes of leakage in one of the heart\u0027s most complex valve structures could lead to improved diagnosis and treatment of the condition.\u003C\/p\u003E\u003Cp\u003EAn estimated 1.6 million Americans suffer moderate to severe leakage through their tricuspid valve, a complex structure that closes off the heart\u0027s right ventricle from the right atrium. Most people have at least some leakage in the valve, but what causes the problem is not well understood.\u003C\/p\u003E\u003Cp\u003EA new study, published online in the journal \u003Cem\u003ECirculation\u003C\/em\u003E on August 1, 2011, found that either dilating the tricuspid valve opening or displacing the papillary muscles that control its operation can cause the valve to leak. A combination of the two actions can increase the severity of the leakage, which is called tricuspid regurgitation.\u003C\/p\u003E\u003Cp\u003E\u0022We think this is the first in vitro investigation into the mechanics of the tricuspid valve, and that our findings into the mechanisms that cause tricuspid regurgitation could lead to improved diagnosis and treatment,\u0022 said Ajit Yoganathan, Regents professor and Wallace H. Coulter Distinguished Faculty Chair in Biomedical Engineering in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.\u003C\/p\u003E\u003Cp\u003EThe tricuspid valve consists of three flaps that open to allow blood to flow from the heart\u0027s upper right chamber to the ventricle. To close the valve, the flaps re-cover the opening, keeping blood from flowing back into the chamber it just left. When the valve is leaky or doesn\u0027t close tightly enough, blood flows backward into the chamber just after the heart contracts.\u003C\/p\u003E\u003Cp\u003ETricuspid regurgitation has been increasingly recognized as a source of disease in patients with chronic mitral valve regurgitation, but surgical repair of the tricuspid valve alone is recommended only in rare cases. If an individual suffers from severe tricuspid regurgitation, surgeons will sometimes repair the tricuspid valve during a surgery to repair other leaky heart valves.\u003C\/p\u003E\u003Cp\u003E\u0022Standard clinical procedures that detail when and how tricuspid valve repairs should be performed need to be developed and this study suggests several items that should be considered,\u0022 said one of the study\u2019s co-authors David H. Adams, chair of the Department of Cardiothoracic Surgery at Mount Sinai Medical Center in New York City. \u0022Current repairs for tricuspid regurgitation focus mainly on remodeling the valve\u0027s opening to correct enlargement, but this study shows that it may also be important to restore the position of the papillary muscles, providing as much overlap as possible, in order to conduct effective and durable tricuspid valve repairs.\u0022\u003C\/p\u003E\u003Cp\u003EWith funding from the American Heart Association, Yoganathan and Coulter Department graduate student Erin Spinner conducted experiments with porcine tricuspid valves to determine possible causes of tricuspid regurgitation. The valves were attached to a plate designed to create physiological dilation and then placed inside a right heart simulator.\u003C\/p\u003E\u003Cp\u003EThe researchers first investigated the effect of dilating the opening of the tricuspid valves. When the openings stretched to an area 40 percent larger than their normal size, a hole appeared in the central region of the valve. The hole caused leakage, and increased in size with further dilatation. This finding surprised the researchers because similar studies using the same method had shown that the heart\u0027s mitral valve could withstand dilation of 75 percent before leaking.\u003C\/p\u003E\u003Cp\u003E\u0022These results tell us that the tricuspid valve is a much more complex valve than the mitral valve, which only has two flaps,\u0022 explained Spinner. \u0022Forming a proper seal over the valve opening might be more difficult with three flaps, which could be why such a large percentage of the population experiences some level of tricuspid regurgitation and why some individuals with annular dilation have tricuspid regurgitation and others do not.\u0022\u003C\/p\u003E\u003Cp\u003EThe research team also investigated the effect of displacing the valve\u0027s three papillary muscles, which attach to the valve via threads. Contraction of the papillary muscles opens the valve and relaxation of the muscles closes the valve. The study showed that papillary displacement alone resulted in significant tricuspid leakage.\u003C\/p\u003E\u003Cp\u003E\u0022While isolated displacement of the papillary muscles is rare, these results are relevant toward understanding what may happen if the size of the valve opening is repaired, but the papillary muscles are left displaced,\u0022 noted Yoganathan.\u003C\/p\u003E\u003Cp\u003EThe study also showed that higher levels of tricuspid leakage resulted when the researchers combined the conditions -- dilation of 40 percent or greater and displacement of all papillary muscles.\u003C\/p\u003E\u003Cp\u003EIn their future work, the Coulter Department researchers plan to look at the effect of pulmonary hypertension on the tricuspid valve, because tricuspid regurgitation usually develops in association with pulmonary hypertension -- which is abnormally high blood pressure in the lungs. They also plan to work with their clinical collaborators to extend their findings to humans.\u003C\/p\u003E\u003Cp\u003E\u0022In our in vitro study we were able to select specific porcine valves, but with human subjects there will be more anatomical variety. For example, two people may have valves of the same diameter, but one person may have longer flaps that are able to compensate for dilation whereas the other might not,\u0022 noted Yoganathan.\u003C\/p\u003E\u003Cp\u003EIn addition to those already mentioned, Pedro del Nido, a professor in the Department of Cardiothoracic Surgery at Children\u0027s Hospital Boston; Emir Veledar, an assistant professor with a joint appointment in the Division of Cardiology and Division of Epidemiology at Emory University; and Coulter Department research engineer Jorge Jimenez and undergraduate students Patrick Shannon and Dana Buice also contributed to this work.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E Georgia Institute of Technology\u003Cbr \/\u003E 75 Fifth Street, N.W., Suite 314\u003Cbr \/\u003E Atlanta, Georgia 30308 USA\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts:\u003C\/strong\u003E Abby Robinson (abby@innovate.gatech.edu; 404-385-3364) or John Toon (jtoon@gatech.edu; 404-894-6986)\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter:\u003C\/strong\u003E Abby Robinson\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EMillions experience leakage from their heart\u0027s tricuspid valve, but what causes it is not well understood. A new study found that either dilating the valve opening or displacing the papillary muscles that control its operation can cause the valve to leak.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Study reports on causes of tricuspid valve leakage."}],"uid":"27206","created_gmt":"2011-08-09 00:00:00","changed_gmt":"2016-10-08 03:09:55","author":"Abby Vogel Robinson","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2011-08-09T00:00:00-04:00","iso_date":"2011-08-09T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"69242":{"id":"69242","type":"image","title":"Tricuspid valve","body":null,"created":"1449177239","gmt_created":"2015-12-03 21:13:59","changed":"1475894606","gmt_changed":"2016-10-08 02:43:26"},"69243":{"id":"69243","type":"image","title":"Right heart simulator","body":null,"created":"1449177239","gmt_created":"2015-12-03 21:13:59","changed":"1475894606","gmt_changed":"2016-10-08 02:43:26"},"69244":{"id":"69244","type":"image","title":"Tricuspid regurgitation","body":null,"created":"1449177239","gmt_created":"2015-12-03 21:13:59","changed":"1475894606","gmt_changed":"2016-10-08 02:43:26"}},"media_ids":["69242","69243","69244"],"related_links":[{"url":"http:\/\/dx.doi.org\/10.1161\/CIRCULATIONAHA.110.003897","title":"Circulation paper"},{"url":"http:\/\/www.bme.gatech.edu\/facultystaff\/faculty_record.php?id=5","title":"Ajit Yoganathan"},{"url":"http:\/\/www.bme.gatech.edu\/","title":"Wallace H. Coulter Department of Biomedical Engineering"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"145","name":"Engineering"},{"id":"146","name":"Life Sciences and Biology"},{"id":"135","name":"Research"}],"keywords":[{"id":"2582","name":"Ajit Yoganathan"},{"id":"594","name":"college of engineering"},{"id":"11533","name":"Department of Biomedical Engineering"},{"id":"13953","name":"Diagnosing"},{"id":"2583","name":"heart"},{"id":"6119","name":"heart valve"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003EAbby Robinson\u003C\/strong\u003E\u003Cbr \/\u003EResearch News and Publications\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=avogel6\u0022\u003EContact Abby Robinson\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-385-3364\u003C\/strong\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["abby@innovate.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}