LAS VEGAS, NV (May 8, 2009) — A new device designed to close a common heart defect known as a patent foramen ovale (PFO) is safe and effective at 90-days follow up, according to a new study released today at the Society for Cardiovascular Angiography and Interventions (SCAI) 32nd Annual Scientific Sessions in Las Vegas.
PFO is a common condition in which a hole that connects the two upper chambers of the heart (atria) during fetal development fails to close properly after birth. About 25 percent of the general population has PFO, which is associated with an increased risk of stroke. PFO may also be associated with migraines and decompression illness in divers.
The FlatStent EF, developed by Coherex Medical,Inc., is unique because it is implanted within the PFO tunnel, leaving a minimal amount of the device exposed to circulation, which could reduce the risk of blood clots. The mechanism of action of the FlatStent EF should limit the incidence of other major complications associated with septal patching devices currently in use, such as erosion, persistent arrhythmia, and valve apparatus distortion.
In the study, 29 of 41 patients (70.7%) who received the FlatStent EF(TM) PFO Closure System had complete PFO closure immediately following implantation. After 90 days, 17 of 19 patients (89%) had complete or clinical closure. The remaining 22 patients had not yet completed the 90-day follow up exam.
“The FlatStent is designed to be safer and easier to use than current PFO closure systems,” said Horst Sievert, MD, professor of internal medicine, cardiology and vascular medicine at the Cardiovascular Center in Frankfurt, Germany, and the study’s principal investigator. “Given the number of patients living with PFO, the results of this study show promise in providing additional treatment options that could help prevent stroke and other conditions associated with PFO.”
In the study, no device-related complications were reported. The 100-patient, multicenter registry study is designed to evaluate 30, 90 and 180-day safety and performance.
Patent Foramen Ovale
Best Publishing Company www.bestpub.com for educational resources for both diving and diving medicine and hyperbaric medicine…. New book PFO and the Diver at www.bestpub.com and Assessment of Diving Medical Fitness for Scuba Divers and Instructors!!!! PFO (Patent foramen ovale) is a persistent opening in the wall of the heart which did not close completely after birth (opening required before birth for transfer of oxygenated blood via the umbilical cord). This opening can cause a shunt of blood from right to left , but more often there is a movement of blood from the left side of the heart (high pressure) to the right side of the heart (low pressure).
People with shunts are less likely to develop fainting or low blood pressure with diving than are obstructive valve lesions (such as mitral valve stenosis or aortic stenosis), but are more likely to develop fluid accumulation in the lungs from heart failure and severe shortness of breath from the effects of combined exercise and water immersion.
Ordinarily, the left to right shunt will cause no problem; the right to left shunt, if large enough, will cause low arterial O2 tension (hypoxia) and severely limited exercise capacity. In divers there is the risk of paradoxical embolism of gas bubbles (passage of bubbles into the arterial circulation) which occur in just about all divers in the venous circulation during decompression.
Blood can flow in both directions with Intra-atrial shunts at various phases of the cardiac cycle and some experts feel that a large atrial septal defect (PFO) is a contra-indication to diving. In addition, a Valsalva maneuver, used by most divers to equalize their ears during descents and ascents, can increase venous atrial pressure to the point that it forces blood containing bubbles across the PFO into the arterial circulation. Thus the usual filtering process of the lungs is by-passed.
Dr. Fred Bove, a Temple University cardiologist, did a search of the literature for patent foramen ovale in relation to diving and diving risks. His conclusion of a meta analysis of 1400 injured divers in about 2.5 million divers (DAN, 1991) in whom the risk of DCS is about 0.05% in the diving population, was that the risk ratio for decompression sickness is increased by a factor of about three for individuals with PFO, and is reduced by a factor of about 2 in individuals who do not have a PFO. It would appear that the risk is low and the significance of the small differences is questionable.
Echocardiography is the tool of choice in making the diagnosis of PFO. However, it’s probably not a good idea to do an echocardiogram on all divers because of the cost/benefit ratio. If you personally are concerned or are having some of the symptoms of decompression illness that are undeserved, then a bubble contrast echocardiogram should be done. Bubble contrast echocardiography appears to be the most sensitive method for detecting a shunt while color flow doppler appeared to be a poor means of detecting the shunt in a transthoracic echo.
There have been recent reports of an association between cerebral emboli, migraines with aura and right to left shunts (PFO).
Philip Foster et al, in the Journal of the Aerospace Medical Association, has an elegant article “Patent Foramen Ovale and paradoxical Systemic Embolism: A Bibliographic Review” in which is presented in a single document a summary of the original findings and views from authors in this field. It is a comprehensive review of 145 peer-reviewed journal articles related to PFO that is intended to encourage reflection on PFO detection methods and on the possible association between PFO and stroke.
The article abstract and related articles can be seen at this address:
http://snipurl.com/4sao
Patent Foramen Ovale Closure - A button closure (Amplatzer) is performed trans venously without entering the chest. About four weeks after the surgery, another echocardiogram is done to verify that the device is still in position.
After two-three weeks there is an overgrowth of endothelial cells covering the device, reducing the risk of infection.
After six to eight weeks the connective tissue has completely filled the spaces in the device and it becomes invisible to ultrasound. Return to diving is usually in six weeks (Wilmshurst), given the full recovery to the satisfaction of the cardiologist/surgeon. Others require a longer wait of twelve weeks.
See article by Wilmshurst, et al at http://heart.bmjjournals.com/cgi/content/full/81/3/257 .
Google Links, PFO and Scuba Diving
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Int J Sports Med. 2009 Feb;30(2):150-3. Epub 2008 Sep 4.
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- Erratum in:
- Int J Sports Med. 2009 Feb;30(2):153.
Relation between right-to-left shunts and spinal cord decompression sickness in divers.
Institute of Naval Medicine, French Navy, Toulon, France. gempp@voila.fr
The role of right-to-left shunting (RLS) in spinal cord decompression sickness (DCS) remains uncertain and could differ according to the distribution of lesion in spinal cord with a higher risk of upper spinal cord involvement in divers presenting a large patent foramen ovale. The aims of this study were to assess the prevalence of RLS with transcranial doppler ultrasonography in 49 divers referred for spinal cord DCS and compare it with the prevalence of RLS in 49 diving controls, and to determine a potential relation between RLS and lesion site of spinal cord. The proportion of large RLS was greater in DCS divers than in healthy control divers (odds ratio, 3.6 [95 % CI, 1.3 to 9.5]; p = 0.017). Shunting was not associated with the increased incidence of cervical spinal cord DCS (OR, 1.1 [95 % CI, 0.3 to 3.9]; p = 0.9) while a significant relationship between large RLS and spinal cord DCS with thoracolumbar involvement was demonstrated (OR, 6.9 [95 % CI, 2.3 to 20.4]; p < 0.001). From the above results, we conclude that the risk of spinal cord DCS in divers with hemodynamically relevant RLS is higher than in divers without RLS, particularly in their lower localization.
PMID: 18773377 [PubMed - indexed for MEDLINE]
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