Review: Detection of patient foramen ovale using transcranial Doppler or standard echocardiography

Enhancing the diagnostic efficacy of right-to-left shunt using robot-assisted transcranial Doppler: a quality improvement project

Background

Stroke is the leading cause of adult disability worldwide, with approximately 30% of strokes remaining cryptogenic. One potential important etiology is a patent foramen ovale (PFO), which may contribute to stroke through paradoxical thromboembolism or in situ thromboembolus formation. Recent advancements in robot-assisted transcranial Doppler (raTCD) have shown increased sensitivity in detecting right-to-left shunt (RLS) compared to transthoracic echocardiography (TTE), particularly in detecting the large shunts which are associated with higher stroke risk.

Methods

We conducted a retrospective quality improvement project at our regional stroke center to compare the performance of TTE and raTCD in identifying RLS in ischemic stroke patients. The study involved 148 patients admitted between February 2021 and February 2023. All patients underwent TTE and raTCD with agitated saline bubble contrast, with additional transesophageal echocardiography (TEE) at the treatment team's discretion. The primary metrics analyzed included differences in overall RLS detection and large RLS detection rates for raTCD, TTE and TEE.

Results

raTCD detected RLS in 60.1% of patients compared to 37.2% with TTE (p < 0.001), with a 42.6% detection rate for large shunts on raTCD versus 23.0% on TTE (p < 0.001). The sensitivity and specificity of raTCD were 92 and 87.5%, respectively, compared to 78.57 and 71.43% for TTE, using TEE as the gold standard. Nine patients underwent PFO closure, all correctly identified with large shunts by raTCD, while TTE missed or underestimated the PFO size in 44% of the cases.

Conclusion

raTCD significantly outperforms TTE in detecting RLS and large shunts, suggesting its integration into standard PFO workup protocols may enhance secondary stroke prevention. These findings support the adoption of raTCD as a complementary diagnostic tool alongside TTE and TEE for more accurate PFO detection and risk stratification.

Genetic variation in patent foramen ovale: a case-control genome-wide association study

Background

Patent foramen ovale (PFO) is a congenital defect between the atria, resulting in abnormal hemodynamics. We conducted a genome-wide association study (GWAS) to identify common genetic variants associated with PFO.

Methods

We performed a whole genome sequencing in a discovery cohort of 3,227 unrelated Chinese participants screened for PFO via contrast transthoracic echocardiography (cTTE). Single-nucleotide polymorphisms (SNPs) associated with PFO were further validated by Sanger sequencing and subsequently were evaluated in a validation cohort. Expression quantitative trait loci (eQTL) analysis was conducted using the GTEx database. Single-cell sequencing analyses with pseudotime trajectory modeling were employed to evaluate their expression in human fetal hearts.

Results

The case-control GWAS of discovery cohort ultimately included 517 cases and 517 demographically matched controls. Of the 7,040,407 variants assessed, we identified rs1227675732 (OR = 2.903; 95% CI, 1.961 to 4.297; p = 3.05 × 10-8), rs62206790 (OR = 2.780; 95% CI, 1.864 to 4.146; p = 2.02 × 10-7), rs879176184 (OR = 2.724; 95% CI, 1.822 to 4.073; p = 4.30 × 10-7) and rs13115019 (OR = 2.437; 95% CI, 1.702 to 3.488; p = 5.80 × 10-7) as high-risk variants for PFO, while rs57922961 (OR = 0.5081; 95% CI, 0.388 to 0.666; p = 6.82 × 10-7) was identified as protective variant. These variations were replicated in the validation cohort (111 cases and 152 controls). Single-cell sequencing showed that CNOT2, KCNMB4, MLLT10, IGBP1, and FRG1 were highly expressed with significant changes during heart development.

Conclusion

The identification of susceptible loci for PFO might provide insights into the pathogenesis of PFO and contribute to understanding heart development.

Clinical Trial Registration

https://www.chictr.org.cn/showproj.html?proj=40590, identifier ChiCTR1900024623.

Techniques for Identifying a Patent Foramen Ovale: Transthoracic Echocardiography, Transesophageal Echocardiography, Transcranial Doppler, Right Heart Catheterization

Noninvasive and invasive imaging modalities play important roles for the detection of patent foramen ovale (PFO). Transthoracic echocardiography or transcranial Doppler bubble study can be used for initial noninvasive PFO screening. For diagnostic confirmation, transesophageal echocardiography bubble study can be utilized, a semiinvasive confirmatory test that can directly visualize a PFO. In selective cases when the diagnosis is in doubt, PFO can be accurately diagnosed invasively with right heart catheterization. Understanding the advantages and limitations of each diagnostic option will help clinicians choose the appropriate test for patients presenting with a PFO-associated condition who may benefit from percutaneous device closure.

Contrast-enhanced transcranial Doppler for the detection of right-to-left shunt: A new provocation method with a syringe-modified Valsalva maneuver

BACKGROUND

Contrast-enhanced transcranial Doppler (cTCD) study has been established as one of the most common investigations for detecting right-to-left shunt (RLS). Although the conventional Valsalva maneuver (c-VM) has been used to increase the sensitivity of cTCD for RLS, efforts are still needed to improve the detection rate further. We proposed a new provocation method with a syringe-modified Valsalva maneuver (sm-VM) during cTCD and compared the efficacy of this strategy with cTCD measured at resting and with the provocation of c-VM.

METHODS

Consecutive patients with suspicion of RLS who underwent cTCD in our institution between September 27, 2021, and April 1, 2022, were included in this study. Examination of cTCD was performed separately at the resting state and provoked with c-VM and sm-VM. The overall proportion of patients with RLS and their distribution with different RLS grades were compared.

RESULTS

A total of 389 patients (mean age: 49.37 years, male: 52.2%) were included in this study. The positive rate for RLS was significantly higher for cTCD detected with sm-VM than those detected at resting state and with c-VM (46.8% vs. 21.6% and 34.2%, all p < .05). Besides, cTCD detected with sm-VM was also associated with a higher proportion of patients with grade III RLS than those detected at resting state and with c-VM (11.3% vs. 1.8% and 0%, all p < .05).

CONCLUSIONS

Compared to cTCD detected at resting state and with c-VM, cTCD with sm-VM could further increase the positive detection rate of RLS.

Comparison of echocardiographic and clinical characteristics in embolic stroke and migraine patients with patent foramen ovale

BACKGROUND

This single-center observational study aimed to compare the echocardiographic and clinical features in patients diagnosed with migraine and embolic stroke of undetermined source (ESUS) who presented with a known patent foramen ovale (PFO).

METHODS

Two-dimensional and color Doppler images were obtained using various transthoracic echocardiography views for both migraine and ESUS patients. Suspected PFO cases underwent further assessment through contrast echocardiography and transesophageal echocardiography (TEE). High-risk PFO characteristics were evaluated using TEE, and the Risk of Paradoxical Embolism (RoPe) score was calculated.

RESULTS

The study included 310 participants (age range: 18-60, 73.2% female), with 43.5% diagnosed with migraine and 56.5% with ESUS. Common comorbidities included diabetes (26.1%). High-velocity shunting through the interatrial septum was observed in 35.5% of patients. ESUS patients were older, with higher rates of diabetes and hypertension, while active smoking was more prevalent among migraine patients. Basic echocardiographic parameters were mostly similar, except for elevated pulmonary artery systolic pressure in ESUS. ESUS patients exhibited a greater occurrence of large microbubble passage through the interatrial septum and longer PFO lengths compared to migraine patients. However, the RoPe and High-risk PFO scores were similar between the groups.

CONCLUSIONS

ESUS patients, characterized by older age and higher rates of diabetes and hypertension, demonstrated increased pulmonary artery pressure, more significant microbubble crossings, and longer PFO lengths. Conversely, migraine patients had a higher prevalence of active smoking. Despite differing clinical profiles, the risk scores for PFO-related embolic events were comparable between the groups. These findings underscore potential distinctions between ESUS and migraine patients with PFO and their implications for management strategies.

Right-to-Left Shunt Evaluation in Cardiac Patent Foramen Ovale Using Bubble Contrast Transcranial Color-Coded Doppler: A Cryptogenic Stroke Case

Traditional diagnosis of patent foramen ovale (PFO) in the heart has involved the use of transcranial Doppler (TCD). However, TCD is essentially a blind test that cannot directly visualize the location of blood vessels. Since TCD relies on qualitative assessments by examiners, there is room for errors, such as misalignment of the ultrasound's angle of incidence with the actual blood vessels. This limitation affects the reproducibility and consistency of the examination. In this study, we presented an alternative approach for assessing right-to-left shunt (RLS) associated with PFO using contrast transcranial color-coded Doppler (C-TCCD) with bubble contrast. The patient under consideration had been diagnosed with an ischemic stroke through imaging, but the subsequent cardiac work-up failed to determine the cause. Employing C-TCCD for RLS screening revealed a confirmed RLS of Spencer's three grades. Subsequently, transesophageal echocardiography (TEE) was conducted to evaluate PFO risk factors, confirming an 8 mm PFO size, a 21 mm tunnel length, a hypermobile interatrial septum, and persistent RLS. The calculated high-risk PFO score was 4 points, categorizing it as a very high risk PFO. This case underscores the importance of C-TCCD screening in detecting RLS associated with PFO, especially in cryptogenic stroke patients, when identifying the underlying cause of ischemic stroke becomes challenging.

Clinical value of microemboli combined with cerebrospinal fluid inflammatory factor level monitoring in predicting recurrent stroke of middle cerebral artery stenosis

OBJECTIVE

To evaluate the clinical value of microemboli combined with cerebrospinal fluid inflammatory factor level monitoring in the prediction of recurrent stroke in middle cerebral artery stenosis.

METHODS

This is a retrospective study. Patients (n=170) who were hospitalized in the Department of Neurology of the First People's Hospital of Jiangxia District from June 2019 to January 2021 with cerebral infarction or transient ischemic attack were included in the study. Among them, 85 patients with ischemic attack were divided into the non-recurrent stroke group (primary onset, n=40) and the recurrent stroke group (history of cerebral infarction or transient ischemic attack within 5 years prior to the onset, n=45). Routine blood biochemical tests were performed using the Olympus 5800 automated chemical analyzer. Cerebrospinal fluid levels of inflammatory factors (TNF-α, IL-6) were detected by ELISA kits. Special Doppler hyperintensities for microemboli in cerebral blood flow were tested by transcranial Doppler ultrasound.

RESULTS

The mean age, statins and LDL-C were higher in the recurrent stroke group than the non-recurrent stroke group (P<0.05). The levels of cerebrospinal fluid TNF-α, PCT, CRP and IL-6 in the recurrent stroke group were higher than the non-recurrent stroke group (P<0.05). The proportion of grade 0 microemboli in the recurrent stroke group was lower than the non-recurrent stroke group (P<0.05), and the proportion of grade 1, 2, 3, 4 and 5 microemboli was higher than the non-recurrent stroke group (P<0.05). The positive rate of microemboli in the recurrent stroke group was higher than the non-recurrent stroke group (P<0.05). The accuracy rate of microemboli combined with cerebrospinal fluid inflammatory factor level monitoring in the recurrent stroke group for the prediction of recurrent stroke due to middle cerebral artery stenosis was higher than that in the non-recurrent stroke group (P<0.05). Increased age, statin use, microembolization, and increased LDL-C, TNF-α, PCT, CRP and IL-6 levels were independent risk factors.

CONCLUSION

Microemboli combined with cerebrospinal fluid inflammatory factor level monitoring can increase the detection rate of recurrent stroke in middle cerebral artery stenosis and prevent vascular events to a great extent.

Adjunct Methods for the Detection of Patent Foramen Ovale: The Contribution of Transcranial Doppler and the Valsalva Manoeuvre

A patent foramen ovale (PFO) is present in 25% of the population. In some patients, especially those without traditional stroke risk factors and with no immediately apparent cause, a cryptogenic stroke may be caused by an embolus passing through the PFO to the systemic circulation. The identification, or indeed exclusion, of a PFO is sought in these patients, most commonly using contrast-enhanced transthoracic or transoesophageal echocardiography. Another method for detecting a PFO is transcranial Doppler, which allows the detection of PFO possibly without the need for an echo laboratory, and with arguably improved sensitivity. This review will focus on transcranial Doppler detection of PFO, with a brief summary of echocardiographic techniques and the use of ultrasound contrast agents, and the role of provocations to increase diagnostic accuracy, specifically the Valsalva manoeuvre. We discuss the phases alongside the direct and indirect signs of an adequate Valsalva manoeuvre.

Sonografisches Neuromonitoring auf der Stroke Unit und in der neurologischen Intensivmedizin

Hintergrund Der Artikel gibt einen Überblick über die aktuellen diagnostischen Einsatzmöglichkeiten sonographischer Anwendung in der neurologischen Intensivmedizin.

Methoden Selektive Literaturrecherche mit kritischer Beurteilung ab dem Jahr 1984 sowie nationaler und internationaler Leitlinien sowie Expertenmeinung.

Ergebnisse Neben der raschen validen Abklärung akuter Schlaganfälle bieten verschiedene neurosonografische Monitoring-verfahren gerade in der Intensivmedizin spezifische Vorteile wie die beliebig häufige Wiederholbarkeit am Patientenbett selbst und die Darstellung in Echtzeit. Innovative Entwicklungen machen die Neurosonografie auch wissenschaftlich zu einem interessanten Gebiet.

Schlussfolgerung Die neurosonografische Diagnostik nimmt seit Jahren einen wichtigen Stellenwert in der neurologischen Intensivmedizin ein. Weitere Anstrengungen sind notwendig, um die Verbreitung der Methode zu fördern und durch wissenschaftliche Evidenz zu stärken.