Accuracy of transcranial Doppler for the diagnosis of intracardiac right-to-left shunt: a bivariate meta-analysis of prospective studies

Patent Foramen Ovale in Fetal Life, Infancy and Childhood

A patent foramen ovale (PFO) is a common, incidental echocardiographic finding in otherwise healthy and asymptomatic infants and children. However, a variety of clinical conditions have been ascribed to the presence of a PFO in childhood, such as cryptogenic stroke, platypnea-orthodeoxia syndrome, decompression sickness and migraine, although the data on these are controversial and sometimes contradictory. This review discusses embryology and correlation with post-natal anatomy, anatomical variations of the atrial septum, diagnostic modalities in special circumstances of PFO associated clinical syndromes, and the role of PFO in congenital heart disease, pulmonary hypertension, dilated cardiomyopathy and heart failure in children who require an extracorporeal membrane oxygenator or ventricular assist device as life support.

Cardiac Imaging After Ischemic Stroke or Transient Ischemic Attack

PURPOSE OF REVIEW

Cardiac imaging after ischemic stroke or transient ischemic attack (TIA) is used to identify potential sources of cardioembolism, to classify stroke etiology leading to changes in secondary stroke prevention, and to detect frequent comorbidities. This article summarizes the latest research on this topic and provides an approach to clinical practice to use cardiac imaging after stroke.

RECENT FINDINGS

Echocardiography remains the primary imaging method for cardiac work-up after stroke. Recent echocardiography studies further demonstrated promising results regarding the prediction of non-permanent atrial fibrillation after ischemic stroke. Cardiac magnetic resonance imaging and computed tomography have been tested for their diagnostic value, in particular in patients with cryptogenic stroke, and can be considered as second line methods, providing complementary information in selected stroke patients. Cardiac imaging after ischemic stroke or TIA reveals a potential causal condition in a subset of patients. Whether systematic application of cardiac imaging improves outcome after stroke remains to be established.

Platypnea-Orthodeoxia Syndrome: Rare or Under-Diagnosed Syndrome? 3 Case Reports and a Literature Review

Platypnea-Orthodeoxia Syndrome (POS) is dyspnea and hypoxemia in the upright position that improves in the supine position. Cardiac POS is predominantly caused by congenital interatrial communications (CIC) paired with changes in the thoracic anatomy, allowing orthostatic right to left cardiac shunting. High suspicion, especially with hypoxemia without significant pulmonary disease, that does not easily correct with supplemental oxygen, should lead the clinician to obtain echocardiographic imaging, documenting right to left shunting, typically through a patent foramen ovale (PFO). Transcatheter closure of the CIC is highly successful in relieving symptoms of dyspnea and resolving hypoxemia in the majority of patients.

Epidemiology of Patent Foramen Ovale in General Population and in Stroke Patients: A Narrative Review

Introduction: Percutaneous closure of patent foramen ovale (PFO) in selected patients with cryptogenic cerebrovascular ischemic events (CEs) decreases the risk of recurrent stroke; however, optimal patient selection criteria are still under investigation. Candidates for PFO closure are usually selected from the pool of CE patients with a high risk of Paradoxical Embolism (RoPE) score. The RoPE score calculates the probability that PFO is causally related to stroke, based on PFO prevalence in patients with CE compared with that in healthy subjects. The latter has been set at 25% based on the average of autopsy and transesophageal echocardiography (TEE) studies.

Methods: We conducted a comprehensive review of studies investigating PFO prevalence in general population and in patients with CE and non-CE using autopsy, TEE, transcranial Doppler (TCD) or transthoracic echocardiography (TTE). Studies were excluded if they (1) reported data from referred subjects with underlying cerebrovascular disease or (2) did not specify etiologically the events.

Results: In healthy/control subjects, PFO prevalence was 24.2% (1,872/7,747) in autopsy studies, 23.7% (325/1,369) in TEE, 31.3% (111/355) in TCD, and 14.7% (186/1,267) in TTE studies. All diagnostic modalities included PFO prevalence was higher in CE compared with healthy/control population [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 2.5–3.8] and compared with non-CE (OR = 2.3, 95% CI = 2.0–2.6). In patients with CE, PFO prevalence in the young compared to the old was higher when the diagnostic modality was TEE (48.9 vs. 27.3%, p < 0.0001, OR = 2.6 with 95% CI = 2.0–3.3) or TCD (58.1 vs. 41%, OR = 1.9, 95% CI = 1.6–2.5), but not TTE (53.3 vs. 37.5%, p = 0.16). Regarding non-CE, PFO prevalence in the young compared to the old was higher when the diagnostic modality was TEE (20 vs. 12.9%, OR = 1.7, 95% CI = 1.0–2.8) but not TTE (10.4 vs. 7.8%, p = 0.75) or TCD (22.8 vs. 20.1%, p = 0.56).

Conclusions: Given the limitations of autopsy and TEE studies, there is good reason not to take a fixed 25% PFO prevalence for granted. The estimation of degree of causality may be underestimated or overestimated in populations with PFO prevalence significantly lower or higher than the established. Given the high sensitivity, non-invasive nature, low cost, and repeatability of TCD, future large-scale TCD-based studies should investigate potential heterogeneity in PFO prevalence in different healthy racial/ethnic populations.

Patent Foramen Ovale Closure: State of the Art

Patent foramen ovale (PFO) is a common abnormality affecting between 20% and 34% of the adult population. For most people, it is a benign finding; however, in some people, the PFO can open widely to enable paradoxical embolus to transit from the venous to arterial circulation, which is associated with stroke and systemic embolisation. Percutaneous closure of the PFO in patients with cryptogenic stroke has been undertaken for a number of years, and a number of purpose-specific septal occluders have been marketed. Recent randomised control trials have demonstrated that closure of PFO in patients with cryptogenic stroke is associated with reduced rates of recurrent stroke. After a brief overview of the anatomy of a PFO, this article considers the evidence for PFO closure in cryptogenic stroke. The article also addresses other potential indications for closure, including systemic arterial embolisation, decompression sickness, platypnoea-orthodeoxia syndrome and migraine with aura. The article lays out the pre-procedural investigations and preparation for the procedure. Finally, the article gives an overview of the procedure itself, including discussion of closure devices.

Management of paradoxical embolism in a patient with coexisting patent foramen ovale and masked pulmonary arteriovenous fistula: A case report

RATIONALE

Paradoxical embolism (PE) is an important cause of cryptogenic stroke, particularly in young patients, which usually have a relation with an unexpected route in circulation. Here we report a rare case of cryptogenic stroke carried 2 uncommon malformations.

PATIENT CONCERNS

A 48-year-old female experienced double neurological events in just 2 months.

DIAGNOSIS

Patent foramen ovale was diagnosed with transesophageal echocardiography and successfully occluded in the first admission due to stroke. In the second admission, chest tomographic angiography found a chordae shadow in the right middle lobe, was the first clue for pulmonary arteriovenous fistula (PAVF), thereafter further confirmed by the enhanced pulmonary computed tomographic angiography.

INTERVENTIONS

This patient then received intervention occlusion therapy with coils for PAVF under the help of microcatheter. Given the possible native origin of the thrombus in PAVF due to the spiral morphology, dual antiplatelet therapy was prescribed for this patient for the first 3 months to prevent device-related embolism after discharge, and the following single antiplatelet therapy was mandated.

OUTCOMES

No recanalization was detected on the follow-up enhanced pulmonary computed tomographic angiography (PCTA), no neurological defect event recurred in the 16 months of follow-up.

LESSONS

Computed tomograph (CT) deserved more value in screening and depicting the morphology of the PAVF, particular in young adults with no apparent arteriosclerotic risk factor. Microcatheter would be helpful for intervention treatment. Antiplatelet therapy might be adequate in specific patients, yet definitely need more evidence to verify.

Diagnosis of Patent Foramen Ovale: The Combination of Contrast Transcranial Doppler, Contrast Transthoracic Echocardiography, and Contrast Transesophageal Echocardiography

Objectives

To access the distinct values of contrast transcranial Doppler (cTCD), contrast transthoracic echocardiography (cTTE), and contrast transesophageal echocardiography (cTEE) in the diagnosis of right-to-left shunt (RLS) due to patent foramen ovale (PFO) and to define the most practical strategy for the diagnosis of PFO.

Methods

102 patients with a high clinical suspicion for PFO had simultaneous cTCD, cTTE, and cTEE performed. The agitated saline mixed with blood was used to detect right-to-left shunt (RLS).

Results

In all 102 patients, the shunt was detected at rest by cTCD in 60.78% of cases, by cTTE in 42.16%, and by cTEE in 47.06%. The positive results of all 3 techniques with Valsalva maneuver (VM) were significantly improved. cTCD showed higher pick-up rate than cTTE (98.04% vs. 89.22%; χ² = 12.452, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm, t = 3.135, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm, t = 3.135, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm, t = 3.135, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm,

Conclusions

The best method to diagnose PFO should be the combination of cTCD, cTTE, and cTEE. And cTCD should be applied as the first choice for screening RLS. Then, cTTE should be performed to quantify the severity of the shunt. Last but not least, cTEE should be performed to assess the morphologies of PFO when the closure is planned. The study provides for clinicians the most practical strategy for diagnosing PFO in the future. However, further trials with a large sample size are required to confirm this finding.

Patent Foramen Ovale, the Role of Antiplatelet Therapy Alone or Anticoagulant Therapy Alone Versus Device Closure for Cryptogenic Stroke: A Review of the Literature and Current Recommendations

Cryptogenic stroke and its relation to the Patent Foramen Ovale (PFO) is a long-debated topic. Recent clinical trials have unequivocally established the relationship between cryptogenic strokes and paradoxical embolism across the PFO. This slit-like communication exists in everyone before birth, but most often closes shortly after birth. PFO may persist as a narrow channel of communication between the right and left atria in approximately 25-27% of adults. In this review, we examine the clinical relevance of the PFO with analysis of the latest trials evaluating catheter-based closure of PFO's for cryptogenic stroke. We also review the current evidence examining the use of antiplatelet medications versus anticoagulants for stroke prevention in those patients with PFO who do not qualify for closure per current guidelines.

The Connection Between Patent Foramen Ovale and Migraine

"Observational studies have identified a relationship between patent foramen ovale (PFO) and migraine headache. In people who have migraine with aura, 40% to 60% have a PFO, compared with 20% to 30% in the general adult population. It is hypothesized that migraine, especially migraine with aura, may be triggered by hypoxemia or vasoactive chemicals (eg, serotonin), which are ordinarily metabolized during passage through the lungs. Although PFO closure is currently not a FDA-approved therapy for migraines, randomized trials suggest that this intervention may benefit a subgroup of migraineurs."

Detection of Patent foramen Ovale with Contrast Enhanced Transcranial Doppler at Divers

Patent foramen ovale (PFO) is a condition present in 25% of the adult population. It is a remnant of fetal foramen ovale which allows blood to pass from the right to the left atrium, bypassing the fetal lungs. In majority adults it does not have any clinical significance, but in some people it may allow shunting of venous blood into the left atrium (right – left – shunt or RLS), circumventing the lung filter, especially during sneezing, cough, lifting heavy equipment. Is such case, PFO may be a route for venous emboli or gas bubbles from veins to the arterial system. It is known as a paradoxical embolism and may be cause of ischaemic stroke or neurologic decompression sickness (DCI), inner-ear DCI and cutis marmorata. Transesophageal echocardiography is considered as a reference standard in detection of intracardial shunts. Its sensitivity and specificity ranges between 94%-100%. However, TEE is an invasive examination with potentially serious side effects. An alternative examination in RLS detection is contrast enhanced Transcranial Doppler (the bubble study or c-TCD). In comparison to TEE, Transcranial Doppler is not invasive, relatively not expensive and save technique. With its high sensitivity and specificity in detection of PFO, 97% and 93% respectively, it may improve detection of RLS and allow to conduct screening examination for PFO in divers.

Transcatheter Closure of Patent Foramen Ovale: Randomized Trial Update

A patent foramen ovale (PFO) is found in about one-quarter of all adults, but the prevalence increases to approximately half of those with a history of a so-called cryptogenic stroke. The true efficacy of PFO closure for prevention of recurrent paradoxical embolism has been debated for years, as the early 3 randomized trials did not show a statistically significant benefit of PFO closure over standard-of-care medical therapy. However, 3 recent randomized trials along with the long-term follow-up data from the largest early trial demonstrated superiority of device closure for secondary stroke prevention.

Patent Foramen Ovale: Pivotal Role of Transesophageal Echocardiography in the Indications for Closure, Assessment of Varying Anatomies and Post-procedure Follow-up

Patent foramen ovale (PFO) is present in 15%-30% of the general population and has been associated with various pathologic states, including cryptogenic stroke, platypnea-orthodeoxia syndrome, decompression sickness and migraine with auras. Transesophageal echocardiography (TEE) has a major role in the diagnostic evaluation of PFO, as well as in the post-procedural assessment after transcatheter closure. The goals of this article were to synthesize the echocardiographic transesophageal techniques required for accurate PFO diagnosis and careful anatomic assessment of its anatomic variants, to focus TEE indications for device closure as complementary to clinical indications and to assess the role of TEE in the post-procedure follow-up.

Cryptogenic Stroke and Patent Foramen Ovale

Nearly one-half of patients with cryptogenic stroke have a patent foramen ovale (PFO). The dilemma of whether to close these PFOs percutaneously, in an effort to reduce the risk of recurrent paradoxical embolism, has been a matter of ongoing debate for more than a decade. Early randomized clinical trials failed to demonstrate a significant benefit of percutaneous PFO closure for secondary prevention of cryptogenic stroke in an intention-to-treat analysis. The long-term follow-up data from the RESPECT trial and 2 new randomized trials (CLOSE and REDUCE) have clarified these findings. They showed that with good patient selection, transcatheter PFO closure significantly reduces the risk of recurrent stroke compared with medical therapy in patients with cryptogenic stroke, with no increased risk of serious adverse events or influence on major bleeding.

Patent foramen ovale and embolic cryptogenic stroke

The paper considers the actual problem of cryptogenic stroke and patent foramen ovale (PFO). It highlights the issues of pathogenesis and role of paradoxical embolism in the development of cerebral circulation disorders. The features of clinical manifestations and neuroimaging pattern of stroke in the presence of PFO are described. Ultrasound diagnostic techniques used to verify a cardiac anomaly are characterized. Approaches to establishing a cause-and-effect relationship between the presence of PFO and the development of stroke are presented. The current possibilities of secondary prevention in this category of patients, in particular the results of studies of percutaneous PFO occlusion, are discussed.

Relation of Patent Foramen Ovale to Acute Mountain Sickness

Over 50% of patients who rapidly ascend to extreme altitudes develop various symptoms known as acute mountain sickness (AMS), which rarely can be life threatening. It is unclear why some patients are more susceptible to AMS than others. Our objective was to determine whether patent foramen ovale (PFO) is a risk factor for AMS. Subjects who had hiked to altitudes above 10,000' (∼3,000 meters) on the John Muir Trail in California were recruited. Participants completed a questionnaire and 2-physician adjudication was performed in regard to AMS status. A transcranial Doppler with agitated saline contrast injection was performed to evaluate the presence or absence of PFO. The primary outcome was the development of AMS. From 2016 to 2018, 137 hikers were recruited into the study. There was a higher prevalence of PFO in hikers with AMS 15 of 24 (63%) compared with hikers without AMS 44 of 113 (39%); p = 0.034. In the multivariate model, the presence of a PFO significantly increased the risk for developing AMS: odds ratio 4.15, 95% confidence intervals 1.14 to 15.05; p = 0.030. In conclusion, hikers with a PFO had significantly higher risk of developing AMS relative to hikers without a PFO. Clinicians should consider PFO a risk factor in patients who plan to hike to high altitudes.

Persistent hypoxemia after an asthma attack

The presence of an unknown intracardiac shunt due to a patent foramen ovale may be an unusual cause of hypoxemia. We report the case of a patient who presented persistent hypoxemia after an adequate treatment for a severe asthma attack requiring intensive care unit admission. The patient underwent a transthoracic microbubbles contrast echocardiography that showed a massive patent foramen ovale. The favorable clinical course and the absence of major signs and symptoms related to patent foramen ovale allowed a conservative approach with a follow-up program. Patent foramen ovale should be suspected in case of persistent hypoxemia after a severe asthma attack had resolved.

Patent Foramen Ovale and Hypoxemia

Patent foramen ovale (PFO), an embryonic remnant of the fetal circulation, is present in 20-25% of adults. Although recent observational studies and clinical trials have established the link between PFO-mediated right-to-left shunting with cryptogenic stroke and migraine with aura, the role of a PFO in exacerbating hypoxemic medical conditions (ie, sleep apnea, chronic obstructive pulmonary disease, pulmonary hypertension, platypnea-orthodeoxia, pulmonary arteriovenous malformation, high-altitude pulmonary edema, and exercise desaturation) remains less understood. PFO-mediated hypoxemia occurs when deoxygenated venous blood from the right atrium enters and mixes with oxygenated arterial blood in the left atrium. Patients with an intracardiac right-to-left shunt may have profound hypoxemia out of proportion to underlying primary lung disease, even in the presence of normal right-sided pressures. The presence of right-to-left cardiac shunting can exacerbate the degree of hypoxemia in patients with underlying pulmonary disorders. In a subset of these patients, percutaneous PFO closure may result in marked improvement in dyspnea and hypoxemia. This review discusses the association between PFO-mediated right-to-left shunting with medical conditions associated with hypoxemia and explores the role of percutaneous PFO closure in alleviating the hypoxemia.

Current management aspects in adult congenital heart disease: non-surgical closure of patent foramen ovale

A patent foramen ovale (PFO) is a remnant interatrial communication, best diagnosed with transoesophageal echocardiography (TOE) and bubble study. Although quite common and often asymptomatic, PFO is associated with cryptogenic stroke and migraine. Approximately one-half of patients with a cryptogenic stroke have a PFO, and the dilemma regarding whether or not to proceed with percutaneous device closure, to reduce the risk of future recurrent events due to paradoxical embolism, has been subject to debate for nearly two decades. Despite promising observational data, initial randomised clinical trials failed to demonstrate superiority of closure over medical therapy. However, long-term follow-up data from one of these early trials, combined with two new randomised trials, have provided more evidence for the benefits of closure in selected patients. This new evidence suggests that younger patients with high-risk features such as an atrial septal aneurysm (ASA) or large interatrial shunt are more likely to benefit from PFO closure, after fastidious exclusion of an alternative cause for the index stroke. However, issues which require further clarification include whether anticoagulant therapy is preferable to antiplatelet therapy for medical management, and which particular type of closure device is optimal. Finally, despite promising retrospective observational data suggesting improvement in migraine attacks after PFO closure, high quality evidence is lacking in this regard.

Transcranial Doppler findings in antiphospholipid syndrome

INTRODUCTION

Transcranial Doppler is a method that enables the assessment of different cerebral hemodynamic parameters. It also allows for the evaluation of the presence of right-to-left circulation shunts (RLS) and for the detection of microembolic signals (MESs), which might be associated with an increased risk of cerebrovascular events. For instance, the presence of MESs on transcranial Doppler in patients with systemic lupus erythematous (SLE) and antiphospholipid syndrome (APS) is associated with an increased risk of stroke. Therefore, transcranial Doppler could be a useful tool for stroke risk stratification in these patients.

OBJECTIVE

Our objective was to evaluate transcranial Doppler cerebral mean blood flow velocities as well as the presence of MESs and RLS in patients with antiphospholipid syndrome and SLE.

PATIENTS AND METHODS

Twenty-two patients with primary APS (PAPS), 24 patients with secondary APS (SAPS), 27 patients with SLE without APS and 21 healthy controls were evaluated. Clinical and epidemiological data were compiled from medical charts, and all subjects underwent transcranial Doppler examination with breath-holding index calculation. Both middle cerebral arteries were monitored for 60 min for the detection of MESs. RLS was investigated with agitated saline injected as a bolus.

RESULTS

There were no significant differences in mean blood flow velocities among the groups. MESs were more frequently found in patients with SLE when compared with controls and patients with APS (SLE: 17.4%, SAPS: 4.3%, PAPS: 0%, controls: 0%, p = 0.03). Anticoagulant therapy was more frequently used in the APS group (PAPS: 81.8%, SAPS: 75.2%, SLE: 1.7%, p < 0.001). Patients with APS had a higher frequency of RLS when compared with volunteers (63.6% versus 38.1%, p = 0.05). Breath-holding index values tended to be lower in patients with SAPS than in control subjects and patients with PAPS and SLE ( p = 0.06).

CONCLUSIONS

Patients with APS had a higher frequency of RLS than healthy controls. This finding alerts to the importance of cardiac investigation in patients with stroke and APS, because further therapies such as RLS occlusion might eventually add protection. The higher frequency of MES in patients with SLE could suggest an effect of anticoagulant therapy on MES prevention, more frequently used in patients with APS.

Transcranial Doppler to detect right-to-left shunt in cryptogenic acute ischemic stroke

OBJECTIVES

We aimed to confirm the sensitivity and specificity of contrast transcranial Doppler (cTCD) in the detection of right-to-left shunt (RLS) compared to the current reference standard (i.e., transesophageal echocardiography-TEE) in patients aged <55 years with a cryptogenic acute ischemic stroke (AIS) or high-risk (ABCD² score ≥4) transient ischemic attack (TIA), and to calculate the real life delay in detecting RLS by cTCD versus TEE in a tertiary care academic stroke center.

METHODS

Consecutive 16- to 54-year-old patients with AIS or high-risk TIA underwent complete diagnostic workup which included, in case of undetermined etiology, cTCD and TEE. Sensitivity and specificity of cTCD, RLS characteristics, and median delay between the two tests were calculated.

RESULTS

Of the 98 included patients, 52 (53%) had a cryptogenic cerebrovascular ischemic event, which displayed a 56% prevalence of RLS related to a patent foramen ovale (PFO) mainly with a high-grade shunt. When comparing TCD with "bubble test" to TEE, sensitivity and specificity were both 100%. Median delays from symptom onset to examination were 2 (min-max 1-10) and 21 (min-max 1-60) days, respectively, for cTCD and TEE. No adverse event occurred during or after cTDC examination.

CONCLUSIONS

Transcranial Doppler with "bubble test" appears as the best screening test for the detection of RLS in young and middle-aged adults with cryptogenic acute cerebral ischemic events to select patients potentially suitable for closure procedure after TEE confirmation.

Patent foramen ovale in an elderly male with multiple embolic infarcts

Patent foramen ovale (PFO) is associated with embolic stroke, particularly in younger patients. In older patients, atrial fibrillation is a more common cause of embolic stroke. A PFO may be considered culpable at higher age when other potential embolic sources are absent or after recurrent stroke despite prophylactic treatment.

Prevalence of patent foramen ovale in cryptogenic transient ischaemic attack and non-disabling stroke at older ages: a population-based study, systematic review, and meta-analysis

BACKGROUND

Percutaneous closure of patent foramen ovale (PFO) has been shown to be superior to medical treatment alone for prevention of recurrent stroke after cryptogenic transient ischaemic attack or non-disabling stroke in patients aged 60 years or younger. The justification for trials in older patients with transient ischaemic attack or stroke depends on whether PFO is shown to be associated with cryptogenic events at older ages, for which existing evidence is conflicting, and on the population burden of PFO-associated events. Therefore, we did a population-based screening study using contrast-enhanced transcranial Doppler (bubble-TCD) to detect probable PFO as indicated by a right-to-left shunt (RLS); we also did a systematic review and meta-analysis to compare our results with previous studies.

METHODS

In this population-based study, nested in the Oxford Vascular Study (OXVASC), we established the prevalence of any RLS, and of large RLS (>20 microbubbles), in consecutive patients attending a rapid-access transient ischaemic attack and stroke clinic, or at 1-month follow-up after stroke unit admission, with transient ischaemic attack or non-disabling ischaemic stroke, comparing cryptogenic events with those of known cause (according to Trial of Org 10172 in Acute Stroke Treatment [TOAST] criteria). We stratified participants by age, and extrapolated data to the UK population. We also did a systematic review of published studies of PFO prevalence (using transthoracic or transoesophageal echocardiography or bubble-TCD) according to stroke subtype, which included older patients and reported age-specific results, and determined by meta-analysis (including the OXVASC data) the pooled odds ratio (95% CI) of finding PFO of any size in cryptogenic events compared with events of known cause, stratified by screening modality (transthoracic or transoesophageal echocardiography or bubble-TCD). The study protocol is registered with PROSPERO, number CRD42018087074.

FINDINGS

Among 572 consecutive patients with transient ischaemic attack or non-disabling stroke between Sept 1, 2014, and Oct 9, 2017 (439 [77%] patients aged >60 years, mean age 70·0 years [SD 13·7]), bubble-TCD was feasible in 523 patients (91%) of whom 397 were aged older than 60 years. Compared with those with transient ischaemic attack or stroke of known cause, patients with cryptogenic events had a higher prevalence of RLS overall (odds ratio [OR] 1·93, 95% CI 1·32-2·82; p=0·001), and in those aged older than 60 years (2·06, 1·32-3·23; p=0·001). When we pooled the OXVASC data with that from two previous smaller studies of bubble-TCD in patients aged 50 years or older, we found an association between RLS and cryptogenic events (OR 2·35, 95% CI 1·42-3·90; p=0·0009; pheterogeneity=0·15), which was consistent with the equivalent estimate from transoesophageal echocardiography studies (2·20, 1·15-4·22; p=0·02; pheterogeneity=0·02). No data on large RLS in patients with TOAST-defined cryptogenic events compared with other events were available from previous studies, but we found no evidence that the association was diminished in such cases. Of 41 patients with large RLS and cryptogenic transient ischaemic attack or non-disabling stroke in our study, 25 (61%) were aged older than 60 years, which extrapolates to 5951 patients per year in the UK (data from mid-2016).

INTERPRETATION

Bubble-TCD was feasible in most older patients with transient ischaemic attack or non-disabling stroke, the association of RLS with cryptogenic events remained at older ages, and the population burden of PFO-associated events is substantial. Randomised trials of PFO closure at older ages are required and should be feasible.

FUNDING

National Institute for Health Research, Oxford Biomedical Research Centre, Wellcome Trust, and Wolfson Foundation.

Patent foramen ovale and cryptogenic stroke: diagnosis and updates in secondary stroke prevention

The patent foramen ovale (PFO), given its high prevalence in the general population and especially in patients with cryptogenic stroke, has long generated investigation and debate on its propensity for stroke by paradoxical embolism and its management for stroke prevention. The pendulum has swung for percutaneous PFO closure for secondary stroke prevention in cryptogenic stroke. Based on a review of current evidence, the benefit from PFO closure relies on careful patient selection: those under the age of 60 years with few to no vascular risk factors and embolic-appearing stroke deemed cryptogenic after thorough evaluation. As these data look towards influencing guideline statements and device approvals in the future, patient selection remains the crucial ingredient for clinical decision making and future trials.

Patent foramen ovale and stroke

A patent foramen ovale (PFO) is a highly prevalent finding in cryptogenic ischaemic stroke, particularly in young adults. A common challenge in clinical practice is to distinguish between incidental and pathogenic PFO. Some clinical features and tools such as the Risk of Paradoxical Embolism score may help determining the probability of a stroke-related PFO. Nonetheless, the best therapeutic option to reduce stroke recurrence after a cryptogenic stroke with PFO has been a matter of debate for a long time. We review the mechanisms of stroke-related PFO, together with its clinical features and diagnostic criteria. In addition, we focus on the methodological details and results from new studies in the field of secondary prevention. In contrast to prior evidence, the data from three recent clinical trials and an updated meta-analysis favour PFO closure over medical treatment after cryptogenic stroke/TIA for the prevention of stroke recurrence. The PFO closure device procedure is not associated with higher mortality or cardiovascular events, except for a small increase in the occurrence of transient atrial fibrillation. Furthermore, the benefit of PFO closure was higher among those with atrial septal aneurysm and PFO with large right-to-left shunt. Future studies should address pending issues such as the option for anticoagulants or antiplatelet in patients not undergoing closure, the duration of antiplatelet treatment after PFO closure and the role of PFO closure in patients older than 60.

Frequency of Patent Foramen Ovale and Migraine in Patients With Cryptogenic Stroke

BACKGROUND AND PURPOSE

Individuals with migraine are at higher risk for stroke, but the mechanism has not been established. On the basis of the association between migraine and intracardiac right-to-left shunt, it has been proposed that stroke in migraineurs could be caused by a paradoxical embolus passing through a patent foramen ovale (PFO) or pulmonary arteriovenous malformation. The aim of this study was to determine the prevalence of PFO with right-to-left shunt in patients who presented with cryptogenic stroke and had a history of migraine.

METHODS

Patients between 18 and 60 years old who presented with an ischemic stroke were characterized based on ASCOD phenotyping (atherosclerosis; small-vessel disease; cardiac pathology; other causes; dissection). A migraine diagnosis was identified by reviewing physician notes, and frequent aura was defined if present in at least 50% of attacks. A PFO with right-to-left shunt diagnosis was identified by the presence of a positive bubble contrast study with either transcranial Doppler, transthoracic, or transesophageal echocardiography.

RESULTS

Of the 712 patients who presented with ischemic stroke, 127 (18%) were diagnosed as cryptogenic; 68 patients had adequate testing for PFO and a documented migraine history. The prevalence of PFO in patients with cryptogenic stroke without migraine was elevated (59%) compared with the general population (18%). Patients with both cryptogenic stroke and migraine had a higher prevalence of PFO (79%). In patients with cryptogenic stroke who had migraine with frequent aura, the prevalence of PFO was 93%. Only 5 patients (4%) had a history compatible with migrainous infarction.

CONCLUSIONS

In patients with cryptogenic stroke who have migraine, there is a high prevalence (79%) of PFO with right-to-left shunt. The timing of the stroke in migraineurs is usually not related to a migraine attack. These observations are consistent with the hypothesis that the mechanism of stroke in migraineurs is most likely because of a paradoxical embolus. Future cryptogenic stroke classification schemes should consider including PFO as a separate etiologic category.

Transcranial Doppler: Uses in Stroke Prevention

Transcranial Doppler (TCD) is useful in stroke prevention for at least three purposes: diagnosis of intracranial stenosis, detection of right-to-left shunt in patients with suspected paradoxical embolism, and detection of microemboli in patients with carotid stenosis. Other uses may include assessment of cerebral blood flow, which is not discussed in this review. TCD saline studies are more sensitive than transesophageal echocardiography, and more strongly predictive of risk of recurrent events. TCD embolus detection is the best-validated method for identifying among patients with asymptomatic carotid stenosis the few who could benefit from carotid endarterectomy or stenting.

Identification and Quantification of Patent Foramen Ovale-Mediated Shunts: Echocardiography and Transcranial Doppler

Once deemed benign, patent foramen ovale (PFO)-mediated right-to-left shunting has now been linked to stroke, migraine, and hypoxemia. Contrast transesophageal echocardiography is considered the standard technique for identifying a PFO, allowing visualization of the atrial septal anatomy and differentiation from non-PFO right-to-left shunts. Transthoracic echocardiography is the most common method for PFO imaging, being cost-effective, but has the lowest sensitivity. Transcranial Doppler is highly sensitive but is unable to differentiate cardiac from pulmonary shunts; it is the best method to quantitate shunt severity, being more sensitive than transthoracic or transesophageal echocardiography so is our preferred screening method for PFO.

Transcranial Doppler to Detect Right to Left Communication: Evaluation Versus Transesophageal Echocardiography in Real Life

We compared transcranial Doppler (TCD) with transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) for the detection of right to left communication (RLC) in the heart. All patients explored from 2013 to 2016 in a vascular medicine unit to detect RLC by TCD were included. Right to left communication was detected by TCD monitoring for microembolic signals after intravenous injection of agitated 5% glucose and air. One hundred one patients were explored for RLC by TCD, 64 by TEE (not possible in 10, bubble injection in 51), and 93 by TTE because of unexplained stroke or arterial thrombosis (51 males, 50 females, age 51.0 ± 15.8 years) (bubble injection in 35). Fifty-three patients were positive after TCD (TEE: 4 negative, TTE: 7 negative). Of the negative patients after TCD, none was positive for TEE and 1 was positive for TTE with no evidence of patent foramen ovale. Transcranial Doppler was sensitive to detect RLC, even in patients with negative TTE or TTE. A negative TEE did not exclude RLC demonstrated by TCD. Transcranial Doppler might be proposed as first line to detect RLC.

PFO Closure for Cryptogenic Stroke: A Review and Clinical Treatment Algorithm

With a high prevalence in the general population of approximately 25%, and a prevalence in the cryptogenic stroke population approaching 40%, the propensity of a patent foramen ovale (PFO) to precipitate or enable stroke, especially in young, otherwise healthy individuals, has been the subject of much debate. With proof of concept achieved via imaging modalities documenting thrombus-in-transit, and the development of minimally-invasive percutaneous approaches to closure, multiple observational studies and, more recently, several completed randomized controlled trials have sought to answer the question of when and in whom PFO closure should occur. We describe the historical context of PFO closure and review the observational and randomized control trial evidence in this field, culminating in the recent Food and Drug Administration approval of the first dedicated closure device for PFO. Guidelines and consensus statements are discussed, and a novel treatment algorithm is proposed. Future directions in PFO closure will include new devices, further data from completed and upcoming clinical trials, and potential expansion into other disease states associated with PFO.

Right-to-left shunt detection sensitivity with air-saline and air-succinil gelatin transcranial Doppler

BACKGROUND

Air-saline transcranial Doppler is nowadays the first-choice examination to identify right-to-left shunt. To increase right-to-left shunt detection in echocardiography, cardiologists also use air-gelatin mixtures, which are more stable, more echogenic, and easier to be prepared.

AIM

We assessed the sensitivity of air-gelatin compared with air-saline for transcranial Doppler right-to-left shunt detection.

METHODS

Air-saline transcranial Doppler, during unilateral middle cerebral artery monitoring at rest and after Valsalva maneuver, was performed in patients referred to our neurosonology laboratory for right-to-left shunt detection. The same transcranial Doppler protocol was repeated with air-gelatin. To consider transcranial Doppler positive for cardiac right-to-left shunt, at least one embolic signal had to be detected within 20″ from contrast injection. Later signals were interpreted of pulmonary origin. Trans-thoracic echocardiography was repeated with both air-saline and air-gelatin.

RESULTS

A total of 97 patients were enrolled; 46 had negative transcranial Doppler for cardiac right-to-left shunt with both air-saline and air-gelatin; out of these, four patients with air-saline plus two more patients with air-gelatin presented late, isolated microemboli, slightly more numerous with air-gelatin: these were interpreted as pulmonary shunts and confirmed with trans-thoracic echocardiography. In 28 patients with already early positive air-saline transcranial Doppler at rest, air-gelatin induced a marked right-to-left shunt increase, facilitating its visualization at trans-thoracic echocardiography. In 23 patients in whom air-saline transcranial Doppler was negative at rest and positive for cardiac right-to-left shunt only after Valsalva maneuver, air-gelatin was able to reveal shunt also at rest.

CONCLUSIONS

Air-gelatin increases right-to-left shunt detection sensitivity with transcranial Doppler in particular at rest, even in patients in whom air-saline mixture fails to identify the shunt. The choice of air-gelatin mixture should be considered for multicentric, clinical, and research trials.

Right-to-left shunt detection using contrast-enhanced transcranial Doppler: A comparison of provocation maneuvers between coughing and a modified Valsalva maneuver

Contrast-enhanced transcranial Doppler (c-TCD) has been used to detect right-to-left shunts (RLS) because it is highly sensitive and cost-effective. The use of provocation maneuvers, such as physiologic maneuvers (e.g., coughing) and the Valsalva maneuver (VM) to transiently increase right atrial pressure and induce RLS increases the sensitivity of RLS detection. In this study, we sought to determine whether coughing is as effective as the VM in aiding the detection of RLS. We evaluated 162 subjects for RLS, using c-TCD under three different conditions: (i) resting state, (ii) coughing, and (iii) modified VM (m-VM), which involved blowing into a tube connected to a sphygmomanometer at 40 mmHg for 10 s. The positive rate of RLS detection with the m-VM was significantly higher than that with coughing. In addition, a difference between the two maneuvers was observed in terms of the degree of RLS seen. The m-VM should be widely used to detect RLS, because it is reliable, standardized, and cost-effective.

Guidelines for the Use of Echocardiography in the Evaluation of a Cardiac Source of Embolism

Embolism from the heart or the thoracic aorta often leads to clinically significant morbidity and mortality due to transient ischemic attack, stroke or occlusion of peripheral arteries. Transthoracic and transesophageal echocardiography are the key diagnostic modalities for evaluation, diagnosis, and management of stroke, systemic and pulmonary embolism. This document provides comprehensive American Society of Echocardiography guidelines on the use of echocardiography for evaluation of cardiac sources of embolism. It describes general mechanisms of stroke and systemic embolism; the specific role of cardiac and aortic sources in stroke, and systemic and pulmonary embolism; the role of echocardiography in evaluation, diagnosis, and management of cardiac and aortic sources of emboli including the incremental value of contrast and 3D echocardiography; and a brief description of alternative imaging techniques and their role in the evaluation of cardiac sources of emboli. Specific guidelines are provided for each category of embolic sources including the left atrium and left atrial appendage, left ventricle, heart valves, cardiac tumors, and thoracic aorta. In addition, there are recommendation regarding pulmonary embolism, and embolism related to cardiovascular surgery and percutaneous procedures. The guidelines also include a dedicated section on cardiac sources of embolism in pediatric populations.

Association of Left Atrial Enlargement with Cortical Infarction in Subjects with Patent Foramen Ovale

Background and Purpose

Left atrial dysfunction has been reported in patients with patent foramen ovale (PFO). Here we investigated the role of left atrial dysfunction in the development of embolic stroke in patients with PFO.

Methods

We identified consecutive patients with embolic stroke of undetermined sources except for PFO (PFO+ESUS). Healthy subjects with PFO served as controls (PFO+control). A stratified analysis by 10-year age group and an age- and sex- matching analysis were performed to compare echocardiographic markers between groups. In the PFO+ESUS group, infarct patterns of PFO-related stroke were determined (cortical vs. cortico-subcortical) and analyzed in correlation with left atrial function parameters.

Results

A total of 118 patients and 231 controls were included. The left atrial volume indices (LAVIs) of the PFO+ESUS patients were higher than those of the PFO+controls in age groups of 40–49, 50–59, and 60–69 years (P<0.001, P=0.003, and P=0.027, respectively), and in the age- and sex-matched analysis (P=0.001). In the PFO+ESUS patients, a higher (>28 mL/m²) LAVI was more associated with the cortical infarct pattern (P=0.043 for an acute infarction and P=0.024 for a chronic infarction, both adjusted for age and shunt amount). The degree of right-to-left shunting was not associated with infarct patterns, but with the posterior location of acute infarcts (P=0.028).

Conclusions

Left atrial enlargement was associated with embolic stroke in subjects with PFO. Left atrial physiology might contribute to the development of PFO-related stroke and need to be taken into consideration for optimal prevention of PFO-related stroke.

Transcranial Doppler ultrasonography: From methodology to major clinical applications

Non-invasive Doppler ultrasonographic study of cerebral arteries [transcranial Doppler (TCD)] has been extensively applied on both outpatient and inpatient settings. It is performed placing a low-frequency (≤ 2 MHz) transducer on the scalp of the patient over specific acoustic windows, in order to visualize the intracranial arterial vessels and to evaluate the cerebral blood flow velocity and its alteration in many different conditions. Nowadays the most widespread indication for TCD in outpatient setting is the research of right to left shunting, responsable of so called “paradoxical embolism”, most often due to patency of foramen ovale which is responsable of the majority of cryptogenic strokes occuring in patients younger than 55 years old. TCD also allows to classify the grade of severity of such shunts using the so called “microembolic signal grading score”. In addition TCD has found many useful applications in neurocritical care practice. It is useful on both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoidal haemorrhage (caused by aneurysm rupture or traumatic injury), traumatic brain injury, brain stem death. It is used also to evaluate cerebral hemodynamic changes after stroke. It also allows to investigate cerebral pressure autoregulation and for the clinical evaluation of cerebral autoregulatory reserve.

Stepwise Progression of Right-to-Left Atrial Shunting through a Combination of Patent Foramen Ovale and Tricuspid Regurgitation

Patent foramen ovale is a common clinical finding that generally becomes a concern in the presence of transient ischemic attack or stroke. Rarely, patent foramen ovale is associated with hypoxemia in the presence of substantial right-to-left atrial shunting. We present the case of an 86-year-old woman with a pacemaker, who was initially asymptomatic notwithstanding a patent foramen ovale. Over 1.5 years, her symptoms progressed in a stepwise fashion, in the setting of progressive pacemaker-associated tricuspid regurgitation. Ultimately, the patient's symptoms and her hypoxemia resolved after percutaneous closure of her patent foramen ovale with use of a 25-mm "Cribriform" occluder device. This case highlights the fact that clinically significant right-to-left shunting requires an anatomic lesion, such as patent foramen ovale, together with elevated right atrial pressure, which in this case was contributed by severe tricuspid regurgitation.

Transcranial Doppler versus transthoracic echocardiography for the detection of patent foramen ovale in patients with cryptogenic cerebral ischemia: A systematic review and diagnostic test accuracy meta-analysis

OBJECTIVE

Patent foramen ovale (PFO) can be detected in up to 43% of patients with cryptogenic cerebral ischemia undergoing investigation with transesophageal echocardiography (TEE). The diagnostic value of transthoracic echocardiography (TTE) in the detection of PFO in patients with cryptogenic ischemic stroke or transient ischemic attack has not been compared with that of transcranial Doppler (TCD) using a comprehensive meta-analytical approach.

METHODS

We performed a systematic literature review to identify all prospective observational studies of patients with cryptogenic cerebral ischemia that provided both sensitivity and specificity measures of TTE, TCD, or both compared to the gold standard of TEE.

RESULTS

Our literature search identified 35 eligible studies including 3,067 patients. The pooled sensitivity and specificity for TCD was 96.1% (95% confidence interval [CI] = 93.0-97.8%) and 92.4% (95% CI = 85.5-96.1%), whereas the respective measures for TTE were 45.1% (95% CI = 30.8-60.3%) and 99.6% (95% CI = 96.5-99.9%). TTE was superior in terms of higher positive likelihood ratio values (LR+ = 106.61, 95% CI = 15.09-753.30 for TTE vs LR+ = 12.62, 95% CI = 6.52-24.43 for TCD; p = 0.043), whereas TCD demonstrated lower negative likelihood values (LR- = 0.04, 95% CI = 0.02-0.08) compared to TTE (LR- = 0.55, 95% CI = 0.42-0.72; p < 0.001). Finally, the area under the summary receiver operating curve (AUC) was significantly greater (p < 0.001) in TCD (AUC = 0.98, 95% CI = 0.97-0.99) compared to TTE studies (AUC = 0.86, 95% CI = 0.82-0.89).

INTERPRETATION

TCD is more sensitive but less specific compared to TTE for the detection of PFO in patients with cryptogenic cerebral ischemia. The overall diagnostic yield of TCD appears to outweigh that of TTE.

PFO: Button me up, but wait … Comprehensive evaluation of the patient

Patent foramen ovale (PFO) is a slit or tunnel-like communication in the atrial septum occurring in approximately 25% of the population. A wide number of pathological conditions have been linked to its presence, most notably, cryptogenic stroke (CS) and migraine. However, in the setting of a neurological event, it is not often clear whether the PFO is pathogenically related to the index event or an incidental finding. Therefore, a detailed analysis of several clues is needed for understanding PFO's clinical significance, with a frequent case-by-case decision about destination therapy. Indeed, the controversy about PFO's pathogenicity prompted a paradigm shift of research interest from medical therapy with antiplatelets or anticoagulants to percutaneous transcatheter closure, in secondary prevention. Observational data and meta-analysis of observational studies had previously suggested that PFO closure with a device was a safe procedure with a low recurrence rate of stroke. To date, however, recent randomized controlled trials have not shown the superiority of PFO closure over medical therapy. Thus, the optimal strategy for secondary prevention of paradoxical embolism in patients with a PFO remains unclear. Moreover, the latest guidelines for the prevention on stroke restricted indications for PFO closure to patients with deep vein thrombosis and high-risk of its recurrence. Given these recent data, in the present review, we critically discuss current treatment options, pointing out the role of a comprehensive patient evaluation in overcoming PFO closure restrictions and planning the best management for each patient.

Patent foramen ovale

Patent foramen ovale (PFO) is the most common congenital heart abnormality of fetal origin and is present in approximately ∼25% of the worldwide adult population. PFO is the consequence of failed closure of the foramen ovale, a normal structure that exists in the fetus to direct blood flow directly from the right to the left atrium, bypassing the pulmonary circulation. PFO has historically been associated with an increased risk of stroke, the mechanism of which has been attributed to the paradoxical embolism of venous thrombi that shunt through the PFO directly to the left atrium. However, several studies have failed to show an increased risk of stroke in asymptomatic patients with a PFO, and the risk of stroke recurrence is low in patients who have had a stroke that may be attributed to a PFO. With the advent of transoesophageal and transthoracic echocardiography, as well as transcranial Doppler, a PFO can be routinely detected in clinical practice. Medical treatment with either antiplatelet or anticoagulation therapy is recommended. At the current time, closure of the PFO by percutaneous interventional techniques does not appear to reduce the risk of stroke compared to conventional medical treatment, as shown by three large clinical trials. Considerable controversy remains regarding the optimal treatment strategy for patients with both cryptogenic stroke and PFO. This Primer discusses the epidemiology, mechanisms, pathophysiology, diagnosis, screening, management and effects on quality of life of PFO.

Transcranial Doppler Ultrasound: Incremental Diagnostic Role in Cryptogenic Stroke Part II

Transcranial Doppler (TCD) ultrasonography is a noninvasive ultrasound study, which has been extensively applied in both outpatient and inpatient settings. Its main use in current clinical practice is the research for “Paradoxical Embolism,” due to migration of thromboembolic material from systemic venous circulation to the left cardiac chambers and arterial circulation through cardiopulmonary shunts such as patent foramen ovale which represents an important cause of cryptogenic stroke, especially in patients under 55 years of age. In this review, we shall describe the incremental diagnostic role in cryptogenic stroke for this imaging modality. TCD not only can be used to detect right-left cardiopulmonary shunts but it also allows to classify the grade of severity of such shunts using the so-called “Microembolic Signals grading score.”