Assessment of atria function after percutaneous closure of atrial septal defect using 2D speckle tracking echocardiography.

BACKGROUND: Percutaneous occlusion of atrial septal defect (ASD) has recently become a standard therapeutic strategy, but little is known about atria function thereafter. Strain analysis by two-dimensional speckle tracking echocardiography (2D-STE) is considered to be a new tool to assess myocardial function. METHODS: This study aimed to evaluate atria function by quantifying longitudinal strain in patients with chronic RV volume overload due to ASD before and after percutaneous closure using 2D-STE. 28 consecutive patients underwent percutaneous closure of ASD (18 female, 10 male) were examined, clinical and echocardiographic evaluation one day before, 1 day, and one month after percutaneous closure of ASD. Peak longitudinal systolic strain and strain rate of both atria were analyzed by 2D-STE. RESULTS: Mean age of the patients was 15.07 ± 8.39 years; mean diameter of ASD was 16.01 ± 2.78 mm; left atrium (LA) diameter significantly increased after ASD closure; and peak longitudinal strain of RA increased significantly one day and one month after ASD closure (48. 77 ± 4.40, vs.55.36 ± 3.70 and, vs. 62.13 ± 3.81%, p = 0.001). LA longitudinal strain significantly decreased after ASD closure (42.55 ± 4.57, vs. 34.79 ± 3.20%, p = 0.001). Furthermore, negative correlation was found between the size of the ASD and delta LA systolic strain and strain rate. CONCLUSIONS: 2D-STE can be considered a feasible and simple technique for assessment of atrial deformation in ASD patients, and it useful to assess the effect of percutaneous ASD closure on atrial reservoir function by measuring peak atrial longitudinal strain.

The Genetic Architecture of a Congenital Heart Defect Is Related to Its Fitness Cost.

In newborns, severe congenital heart defects are rarer than mild ones. This epidemiological relationship between heart defect severity and incidence lacks explanation. Here, an analysis of ~10,000 Nkx2-5+/- mice from two inbred strain crosses illustrates the fundamental role of epistasis. Modifier genes raise or lower the risk of specific defects via pairwise (G×GNkx) and higher-order (G×G×GNkx) interactions with Nkx2-5. Their effect sizes correlate with the severity of a defect. The risk loci for mild, atrial septal defects exert predominantly small G×GNkx effects, while the loci for severe, atrioventricular septal defects exert large G×GNkx and G×G×GNkx effects. The loci for moderately severe ventricular septal defects have intermediate effects. Interestingly, G×G×GNkx effects are three times more likely to suppress risk when the genotypes at the first two loci are from the same rather than different parental inbred strains. This suggests the genetic coadaptation of interacting G×G×GNkx loci, a phenomenon that Dobzhansky first described in Drosophila. Thus, epistasis plays dual roles in the pathogenesis of congenital heart disease and the robustness of cardiac development. The empirical results suggest a relationship between the fitness cost and genetic architecture of a disease phenotype and a means for phenotypic robustness to have evolved.

Resource utilisation in paediatric patients with secundum atrial septal defects.

BACKGROUND: There is variation in care of secundum atrial septal defects. Defects <3 mm and patent foramen ovale are not clinically significant. Defects >3 mm are often followed clinically and may require closure. Variation in how these lesions are monitored may result in over-utilisation of routine studies and higher than necessary patient charges. PURPOSE: To determine utilisation patterns for patients with secundum atrial septal defects diagnosed within the first year of life and compare to locally developed optimal utilisation standard to assess charge savings. METHODS: This was a retrospective chart review of patients with secundum atrial septal defects diagnosed within the first year of life. Patients with co-existing cardiac lesions were excluded. Total number of clinic visits, electrocardiograms, and echocardiograms were recorded. Total charge was calculated based on our standard institutional charges. Patients were stratified based on lesion and provider type and then compared to "optimal utilisation" using analysis of variance statistical analysis. RESULTS: Ninety-seven patients were included, 40 had patent foramen ovale (or atrial septal defect <3 mm), 43 had atrial septal defects not requiring intervention and 14 had atrial septal defects requiring intervention. There was a statistically significant difference in mean charge above optimal for these lesions of $1033, $2885, and $5722 (p < 0.02), respectively. There was statistically significant variation of charge among types of provider as well. Average charge savings per patient would be $2530 with total charge savings of $242,472 if the optimal utilisation pathway was followed. CONCLUSION: Using optimal utilisation and decreasing variation could save the patient significant unnecessary charges.

Endothelialization of an Amplatzer Septal Occluder Device 6 Months Post Implantation: Is This Enough Time? An In Vivo Angioscopic Assessment.

The current guidelines recommend a minimum of 6 months of antithrombotic and antibiotic prophylaxis following septal occluding device placement for transcatheter closure of atrial septal defect. Full neoendothelialization is thought to be completed within 6 months of device implantation; however, there is no method available that can assess the level of neoendothelialization in vivo. This report therefore evaluates endothelialization in vivo and demonstrates that 6 months of postimplantation prophylactic therapy may not provide sufficient time for adequate endothelialization. Further investigations are warranted to determine the optimal duration of these treatments after atrial septal defect closure.

[Demographic analysis of a congenital heart disease clinic of the Mexican Institute of Social Security, with special interest in the adult]. / Análisis demográfico de una clínica de cardiopatías congénitas del Instituto Mexicano del Seguro Social, con interés en el adulto.

INTRODUCTION: Congenital heart disease (CHD) has an incidence of 8-10 cases per 1000 live births. In Mexico, there are 18,000-20,000 new cases per year. Most tertiary care centers for CHD attend only pediatric population; the Mexican Institute of Social Security (IMSS) has a clinic that attends pediatric and adult population. OBJECTIVE: To analyze the demographic aspects of the CHD clinic of IMSS. METHODS: From 2011 to 2016 a cross-sectional study of the CC clinic of a third level hospital of the IMSS, including all patients with confirmed structural heart disease of recent diagnosis was carried out. The sex, age, reference entity, antecedent of pregnancy and treatment were registered. The population was divided into age ranges (<2 years, 2.1-6 years, 6.1-10 years, 10.1-17 years and >17.1 years). Descriptive statistics and χ2 test were used in qualitative variables. RESULTS: 3,483 patients with CHD (male:female ratio, 0.8:1.2) were included. Increased pulmonary flow acyanogenic cardiopathies were the most frequent CHD group (47.2%), with atrial septal defect being the most frequent diagnosis overall; 25.6% were adults and 35% of women with a history of pregnancy. Chiapas was Federal entity with greater proportion of patients diagnosed in the adult stage (33.82%); 7% were not candidates for any treatment for complications of the disease. CONCLUSIONS: CHD is a late diagnosis; it is necessary to create a national register to promote new health policies and a rational distribution of resources for these patients.

Análisis demográfico de una clínica de cardiopatías congénitas del Instituto Mexicano del Seguro Social, con interés en el adulto / Demographic analysis of a congenital heart disease clinic of the Mexican Institute of Social Security, with special interest in the adult

Resumen Introducción: Las cardiopatías congénitas (CC) en México se presentan con una cifra estimada entre 18,000-20,000 nuevos casos por año. La mayor parte de los centros que atienden a estos enfermos son exclusivamente pediátricos y el Instituto Mexicano del Seguro Social (IMSS) cuenta con una clínica que atiende a todas las edades. Objetivo: Analizar los aspectos demográficos de una clínica de CC del niño y del adulto del IMSS. Métodos: De 2011 a 2016 se realizó un estudio transversal de la clínica de CC de un hospital de tercer nivel del IMSS, incluyendo todos los pacientes con cardiopatía estructural confirmada de reciente diagnóstico. Se registró el sexo, la edad, la entidad federativa de referencia, el antecedente de embarazo y el tratamiento. Se dividió a la población en rangos de edades (< 2 años, 2.1-6 años, 6.1-10 años, 10.1-17 años y > 17.1 años). Se empleó estadística descriptiva y prueba de y2 en las variables cualitativas. Resultados: Tres mil cuatrocientos ochenta y tres enfermos con CC (relación hombre:mujer,0.8:1.2), las cardiopatías acianógenas de flujo pulmonar aumentado son el grupo más grande (47.2%); 25.6% fueron adultos y 35% de las mujeres con antecedente de al menos una gesta. En general la cardiopatía más frecuente fue la comunicación interauricular. La entidad federativa con mayor frecuencia de adultos de reciente diagnóstico fue Chiapas (33.82%); el 7% no fueron candidatos a ningún tratamiento por complicaciones inherentes a la cardiopatía. Conclusiones: Existe un diagnóstico tardío de la atención de las CC en la etapa adulta. Es necesario crear un registro nacional para promover nuevas políticas de salud y distribución de recursos destinados a estos pacientes.

Abstract Introduction: Congenital heart disease (CHD) has an incidence of 8-10 cases per 1000 live births. In Mexico, there are 18,000-20,000 new cases per year. Most tertiary care centers for CHD attend only pediatric population; the Mexican Institute of Social Security (IMSS) has a clinic that attends pediatric and adult population. Objective: To analyze the demographic aspects of the CHD clinic of IMSS. Methods: From 2011 to 2016 a cross-sectional study of the CC clinic of a third level hospital of the IMSS, including all patients with confirmed structural heart disease of recent diagnosis was carried out. The sex, age, reference entity, antecedent of pregnancy and treatment were registered. The population was divided into age ranges (< 2 years, 2.1-6 years, 6.1-10 years, 10.1-17 years and > 17.1 years). Descriptive statistics and y2 test were used in qualitative variables. Results: 3,483 patients with CHD (male:female ratio, 0.8:1.2) were included. Increased pulmonary flow acyanogenic cardiopathies were the most frequent CHD group (47.2%), with atrial septal defect being the most frequent diagnosis overall; 25.6% were adults and 35% of women with a history of pregnancy. Chiapas was Federal entity with greater proportion of patients diagnosed in the adult stage (33.82%); 7% were not candidates for any treatment for complications of the disease. Conclusions: CHD is a late diagnosis; it is necessary to create a national register to promote new health policies and a rational distribution of resources for these patients.

Transcatheter Versus Surgical Closure of Atrial Septal Defects in Children: A Value Comparison.

OBJECTIVES: The purpose of this study was to determine whether a transcatheter procedure or surgical closure offers a better value proposition for atrial septal defect (ASD) closure. BACKGROUND: Secundum ASDs are common congenital heart defects with both transcatheter and surgical treatment options. Although both options have been shown to have excellent results in children, the relative value of the 2 procedures is unclear. METHODS: Using data from the Pediatric Hospital Information System for 2004 to 2012, we compared the value of transcatheter versus surgical ASD closure for children ages 1 to 17 years, with value being defined as outcomes relative to costs. Total charges for procedure-related encounters were converted to costs using hospital-specific cost-to-charge ratios, and all costs were adjusted for inflation to reflect 2012 dollars. RESULTS: There were 4,606 transcatheter procedures and 3,159 surgeries at 35 children's hospitals. Those undergoing transcatheter closure were more likely to be older (5.6 years vs. 4.5 years, p < 0.0001). There was no mortality in either group. Children with a surgical procedure had a longer length of stay (4.0 days vs. 1.5 days, p < 0.0001), were more likely to have an infection (odds ratio: 3.73, p < 0.0001) or procedural complication (odds ratio: 6.66, p < 0.0001). Costs for transcatheter procedure encounters were lower than costs for surgical encounters (mean of $19,128 vs. $25,359, p < 0.0001). CONCLUSIONS: Both transcatheter and surgical ASD closure had excellent short-term outcomes, but transcatheter procedures had lower lengths of stay, rates of infection, and complications, resulting in lower overall costs. For children who are eligible, transcatheter ASD closure provides better short-term value than surgery.

Transcatheter closure of patent ductus arteriosus and atrial septal defect without on-site surgical backup: a two-year experience in an African community.

Congenital heart disease contributes significantly to the health burden of children in Nigeria. Interventions for congenital heart disease have been available in the developed world since the first report on device closure of patent ductus arteriosus (PDA) in 1967 by Porstmann. However, this did not start in Nigeria until October 2010. This study aimed to document the profiles of the patients who had undergone interventions for congenital heart diseases since the availability of the procedure, the challenges encountered, and the prospects associated with the interventions at the study site. All the patients referred to undergo interventions for congenital heart disease at the study center between October 2010 and 2012 were studied. The profile of the patient, including diagnosis at referral, indication for interventions, and interventions performed, were documented. The patients ranged in age from 3 to 62 years (mean age, 13.54 ± 17.7 years), and the male-to-female ratio was 1:3. The diagnosis at referral included PDA in 10 (83 %) of the 12 patients and secundum atrial septal defect in 2 patients (17 %). They all had transcatheter closure of the defects. Interventional procedures for congenital heart diseases currently are available locally, but the high degree of manpower training required, the cost, and the local availability of consumables are major factors limiting their use. Regional and international collaboration could be mutually beneficial.

Prevalence of treatment, risk factors, and management of atrial septal defects in a pediatric Medicaid cohort.

Atrial septal defects (ASDs) vary greatly depending on their size, age at closure, and clinical management. This report characterizes the prevalence, complexity, and clinical management of these lesions in a statewide pediatric cohort and examines predictors for receiving closures. A 15-year Medicaid data set (1996-2010) from one state was analyzed. The selection criteria specified patients 17 years of age or younger with a diagnosis of ASD primum, secundum, or sinus venosus on one or more service visits to a pediatrician or pediatric cardiologist. During the 15-year period, ASDs represented a prevalence rate for treatment of 0.47/1000 CHDs identified, with 61 % presenting as complex lesions. Concomitant cardiac anomalies that might have a negative impact on prognosis were present including patent ductus arteriosus (26.1 %), pulmonary hypertension (3.8 %), and supraventricular tachycardia (2.4 %). Pharmacologic treatments, predominantly diuretics, were prescribed for 21 % of the cohort. Both surgical closures (6.3 %) and transcatheter closures (1.4 %) were used for ASD secundum cases, whereas surgical closures predominated for ASD primum (25.6 %) and sinus venosus (13.5 %) lesions. The postoperative follow-up period was two to three times longer for children with ASD primum or sinus venosus than for those with ASD secundum (average, ~1 year). Factors predicting the likelihood of having ASD closure were older age, having a concomitant patent ductus arteriosus (PDA) repair, treatment with ibuprofen, having two or more concomitant CHDs, and receiving diuretics or preload/afterload-reducing agents. Care of ASDs in routine practice settings involves more complications and appears to be more conservative than portrayed in previous investigations of isolated ASDs.

Lower risk of decompression sickness after recommendation of conservative decompression practices in divers with and without vascular right-to-left shunt.

INTRODUCTION: A vascular right-to-left shunt (r/l shunt) is a well-known risk factor for the development of decompression sickness (DCS). No studies to date have examined whether divers with a history of DCS with or without a r/l shunt have a reduced risk of suffering recurrent DCS when diving more conservative dive profiles (CDP). METHODS: Twenty-seven divers with a history of DCS recommended previously to dive more conservatively were included in this study and retrospectively interviewed by phone to determine the incidence of DCS recurrence. RESULTS: Twenty-seven divers performed 17,851 dives before examination in our department and 9,236 after recommendations for conservative diving. Mean follow up was 5.3 years (range 0-11 years). Thirty-eight events of DCS occurred in total, 34 before and four after recommendation of CDP. Four divers had a closure of their patent foramen ovale (PFO). A highly significant reduction of DCS risk was observed after recommendation of CDP for the whole group as well as for the sub-groups with or without a r/l shunt. A significant reduction of DCS risk in respect to r/l shunt size was also observed. DISCUSSION: This study indicates that recommendations to reduce nitrogen load after DCS appear to reduce the risk of developing subsequent DCS. This finding is independent of whether the divers have a r/l shunt or of shunt size. The risk of suffering recurrent DCS after recommendation for CDP is less than or equal to an unselected cohort of divers. CONCLUSION: Recommendation for CDP seems to significantly reduce the risk of recurrent DCS.

Clinical differentiation of patent foramen ovale and secundum atrial septal defect: a survey of pediatric cardiologists in Dallas, Texas, USA.

BACKGROUND: Public health birth defect surveillance registries rely on health care provider diagnosis and definition of congenital anomalies. Major anomalies are likely to have consistent diagnoses across providers; however, definition of some more common, often minor, defects can be problematic. Of particular frustration are the transient neonatal heart findings: patent ductus arteriosus, patent foramen ovale, and pulmonary artery branch stenosis. Under certain circumstances these findings may be considered true anomalies-patent foramen ovale (PFO) as a clinical finding overlaps significantly with atrial septal defect (ASD) of secundum type, the latter being considered a true congenital malformation. Some criteria must be established to separate these conditions in case ascertainment. It is therefore helpful to understand the clinical definitions of patent foramen ovale and secundum atrial septal defect. METHODS: Pediatric cardiologists in the greater Dallas, Texas metropolitan area were surveyed by telephone, fax, and/or email and asked what criteria they use to distinguish a PFO from a secundum ASD. This was an open-ended question. No baseline parameters were suggested or introduced by the interviewer. Pediatric cardiology fellowship training was identified for each physician to examine the hypothesis that graduates of a given program would use the same diagnostic criteria. RESULTS: Responses were obtained from 22 of 23 pediatric cardiologists. Four measurement criteria were identified: size of the opening, presence or absence of a flap of septal tissue, appearance of the defect on echocardiogram and presence/absence/amount of blood shunting across through the opening. Though there was overlap, diagnostic criteria differentiating PFO and secundum ASD varied among pediatric cardiologists. Two fellowship programs were well represented by the respondent population. Eight respondents were trained at Fellowship 1 and 5 at Fellowship 2. Place of fellowship training was not a strong indicator of which diagnostic criteria were used, even when graduates were in practice together. Physicians in private practice were more likely to report objective measurements as bases for their diagnostic decision. CONCLUSIONS: The pronounced variability in clinical definitions will be a problem for birth defect surveillance and research based upon the resultant database. When different physicians use different diagnostic criteria for borderline defects, it is impossible to know whether a defect ascertained and coded with a standard protocol is the same across the population. Since it is unlikely that consistent diagnostic criteria can be put in place, the surveillance program is burdened with compensating for the variability.

Assessment of atrial septal defects in adults comparing cardiovascular magnetic resonance with transoesophageal echocardiography.

BACKGROUND: Many adult patients with secundum-type atrial septal defects (ASDs) are able to have these defects fixed percutaneously. Traditionally, this has involved an assessment of ASD size, geometry and atrial septal margins by transoesophageal echocardiography (TOE) prior to percutaneous closure. This is a semi-invasive technique, and all of the information obtained could potentially be obtained by non-invasive cardiovascular magnetic resonance (CMR). We compared the assessment of ASDs in consecutive patients being considered for percutaneous ASD closure using CMR and TOE. METHODS: Consecutive patients with ASDs diagnosed on transthoracic echocardiography (TTE) were invited to undergo both CMR and TOE. Assessment of atrial septal margins, maximal and minimal defect dimensions was performed with both techniques. Analyses between CMR and TOE were made using simple linear regression and Bland Altman Analyses. RESULTS: Total CMR scan time was 20 minutes, and comparable to the TOE examination time. A total of 20 patients (M:F = 5:15, mean age 42.8 years +/- 15.7) were included in the analyses. There was an excellent agreement between CMR and TOE for estimation of maximum defect size (R = 0.87). The anterior inferior, anterior superior and posterior inferior margins could be assessed in all patients with CMR. The posterior superior margin could not be assessed in only one patient. Furthermore, in 1 patient in whom TOE was unable to be performed, CMR was used to successfully direct percutaneous ASD closure. CONCLUSIONS: CMR agrees with TOE assessment of ASDs in the work-up for percutaneous closure. Potentially CMR could be used instead of TOE for this purpose.

Electrocardiographic screening in children with attention-deficit hyperactivity disorder.

Some investigators have suggested that children receiving stimulant medications to manage attention-deficit hyperactivity disorder should undergo screening electrocardiography to identify asymptomatic cardiac disease. However, no study to date has examined the efficacy and costs of this strategy. In the present study we sought to determine the utility of electrocardiographic screening in children with attention-deficit hyperactivity disorder. We reviewed the clinical experience of electrocardiographic screening of subjects with attention-deficit hyperactivity disorder <21 years of age from April to September 2008. Additional cardiac care and testing that resulted from an abnormal initial electrocardiogram were recorded. Screening electrocardiograms were obtained in 1,470 children with attention-deficit hyperactivity disorder and were interpreted as abnormal in 119 subjects (8.1%). Further evaluation of these 119 subjects included 63 transthoracic echocardiograms, 5 stress tests, and 9 Holter monitor studies. Cardiac disease was identified in 5 subjects (0.3% of entire cohort), yielding a positive predictive value of 4.2%. Cardiac diagnoses included ventricular pre-excitation syndrome (n = 2), bicuspid aortic valve (n = 2), and moderate secundum atrial septal defect (n = 1). The mean cost of electrocardiographic screening including further testing for subjects with abnormal initial screen results was $58 per child. The mean cost to identify a true-positive result was $17,162. In conclusion, electrocardiographic screening for children with attention-deficit hyperactivity disorder can successfully identify cardiac disease in otherwise asymptomatic subjects, although the positive predictive value is low. Ongoing studies are needed to know what role electrocardiographic screening should play in the management of children with attention-deficit hyperactivity disorder.

An assessment of the electrocardiogram as a screening test for large atrial septal defects in children.

BACKGROUND AND PURPOSE: The electrocardiogram (ECG) is commonly used as a screening tool for diagnosis of the ostium secundum atrial septal defect (ASD). We sought to analyze the utility of conventional ECG criteria in detecting right ventricular enlargement (RVE) due to the presence of an ASD. METHODS: Patients who underwent transcatheter or surgical closure of an isolated ASD between 1997 and 2004 were included if an ECG was performed less than 9 months before ASD closure and had echocardiographic RVE. RESULTS: Of 99 children (aged 6.8 +/- 4.7 years; range, 1-18 years) with RVE and ASD, 57% had an ECG that met 1 or more RVE criteria. The sensitivity of ECG increased to 70% in younger patients and to 80% for the largest defects. CONCLUSIONS: Electrocardiographic criteria for RVE are present in just more than over half of young patients with large ASDs. Although ECG is more sensitive in younger patients, it is unreliable as a screen for this lesion.

Patent foramen ovale: assessment, clinical significance and therapeutic options.

Foramen ovale plays an important function in the fetus but is of no physiologic significance after birth and closes in most individuals. In about one fourth of the population, however, foramen ovale remains open for life and has been associated with cerebrovascular accidents, especially in younger patients, presumably through paradoxical embolism. Patent foramen ovale (PFO) has also been associated with hypoxia, migraine headaches and neurologic findings of decompression illness in scuba divers. Availability of transesophageal echocardiography and its frequent use in the management of patients with stroke has lead to frequent detection of PFO. In addition, the recent development of devices and techniques for percutaneous closure of PFO has resulted in widespread enthusiasm for such interventions, even when a clear etiologic role for PFO may not be established. In the United States, the Federal Drug Administration (FDA) has approved two such devices through compassionate investigational device exemption without adequate data from large randomized clinical studies. Other such devices are undergoing evaluation in clinical trials. Expert opinions have been helpful for clinical decision making in management of patients with PFO associated with stroke, hypoxia, decompression sickness and migraine headaches.

Long-term outcome after surgical closure of atrial septal defect in childhood with extensive assessment including MRI measurement of the ventricles.

Surgical closure of the secundum type of atrial septal defect (ASD) in childhood leads to excellent survival. However, relevant morbidity has been reported. Transcatheter closure of these defects has now become an alternative approach. To compare the results of the two different interventions, reliable data are needed on the long-term morbidity after defect closure with both methods. Patients were evaluated after a minimum of 10 years after surgical closure of an ASD in childhood. Assessment included analysis of perioperative data, interview, clinical examination, electrocardiogram, (ECG), 24-hour ECG, ergometry, chest radiograph, echocardiography, and MRI. A total of 66 patients underwent operation between 1971 and 1986 at our institution. Forty-eight of them (73%) were interviewed and 38 (58%) participated fully in the study program. Eighteen (27%) either refused to participate or were lost to follow-up. There were no substantial residual disorders, such as arrhythmias, right-sided heart dilatation, pulmonary hypertension, or reduced work capacity. Surgical closure of an ASD in childhood has an excellent long-term outcome. Surgical closure is thus the standard against which transcatheter closure needs to be measured.

Can transcranial Doppler discriminate between solid and gaseous microemboli? Assessment of a dual-frequency transducer system.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasound can reliably detect both gaseous and solid cerebral emboli. However, conventional equipment is unable to discriminate between gaseous and solid emboli. This is a major limitation in situations in which the 2 coexist, because they may have very different clinical relevance. Recently, a novel Embo-Dop system, using insonation at 2 ultrasound transducer frequencies, has been developed. An initial study with a small sample size suggested it provided excellent discrimination. We performed a validation study in subjects with embolic signals of known nature. METHODS: Gaseous embolic signals were obtained in 7 patients with known patient foramen ovale by intravenous injection of agitated saline injections. Solid embolic signals were obtained in patients with symptomatic carotid stenosis (N=23). Discrimination of the 2 using the Embo-Dop system dual-frequency system was assessed. It was compared with discrimination using embolic signal maximum intensity with an intensity threshold. RESULTS: One hundred forty-five solid embolic signals were recorded from carotid stenosis patients. Seventy-three were classified as solid and 72 as gaseous by the Embo-Dop system. Six hundred forty-eight gaseous embolic signals were recorded from 7 patients with patent foramen ovale. Six hundred twenty-five were classified as gaseous and 23 as solid. This gave a sensitivity of 50.3% and specificity of 96.5% for detecting solid embolic signals. Discrimination was better than using a simple intensity threshold. CONCLUSIONS: The Embo-Dop dual-frequency system allows better discrimination than a simple intensity threshold but it is not accurate enough for use in clinical or research studies. Further work is needed to develop reliable clinical systems for discrimination of emboli.