Power M-Mode Transcranial Doppler for Diagnosis of Patent Foramen Ovale and Assessing Transcatheter Closure

European Stroke Organisation (ESO) Guidelines on the diagnosis and management of patent foramen ovale (PFO) after stroke

Patent foramen ovale (PFO) is frequently identified in young patients with cryptogenic ischaemic stroke. Potential stroke mechanisms include paradoxical embolism from a venous clot which traverses the PFO, in situ clot formation within the PFO, and atrial arrhythmias due to electrical signalling disruption. The purpose of this guideline is to provide recommendations for diagnosing, treating, and long-term managing patients with ischaemic stroke and PFO. Conversely, Transient Ischaemic Attack (TIA) was not considered an index event in this context because only one RCT involved TIA patients. However, this subgroup analysis showed no significant differences between TIA and stroke outcomes. The working group identified questions and outcomes, graded evidence, and developed recommendations following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach and the European Stroke Organisation (ESO) standard operating procedure for guideline development. This document underwent peer-review by independent experts and members of the ESO Guideline Board and Executive Committee. The working group acknowledges the current evidentiary gap in delineating an unequivocal diagnostic algorithm for the detection of PFO. Although transoesophageal echocardiography is conventionally held as the most accurate diagnostic tool for PFO identification, its status as the 'gold standard' remains unsubstantiated by rigorously validated evidence. We found high-quality evidence to recommend PFO closure plus antiplatelet therapy in selected patients aged 18-60 years in whom no other evident cause of stroke is found but a PFO (i.e. PFO-associated stroke). The PASCAL classification system can be used to select such candidates for PFO closure. Patients with both a large right-to-left shunt and an atrial septal aneurysm benefit most from PFO closure. There is insufficient evidence to make an evidence-based recommendation on PFO closure in patients older than 60 and younger than 18 years. We found low quality evidence to suggest against PFO closure in patients with unlikely PFO-related stroke according to the PASCAL classification, except in specific scenarios (Expert Consensus). We suggest against long-term anticoagulation in patients with PFO-associated stroke unless anticoagulation is indicated for other medical reasons. Regarding the long-term AF monitoring after PFO closure, the working group concluded that there remains significant uncertainty regarding the risks and benefits associated with the use of long-term cardiac monitoring, such as implantable loop recorders. This document provides additional guidance, in the form of evidence-based recommendations or expert consensus statements, on diagnostic methods for PFO detection, and medical management after PFO closure.

The size distribution of the agitated saline microbubbles for contrast transcranial Doppler generated using standard manual methods

Agitated saline microbubbles (MBs) are a common contrast agent for determining right-to-left shunt (RLS) by the contrast transcranial Doppler (c-TCD). The size of the generated bubbles is not standardized in clinical practice. MBs were generated using the recommended manual method by reciprocating motion through two syringes. The bubble size distributions (BSD) were measured using the microscopic shadow imaging technique. The results show that the diameter of MBs is mainly distributed between 10 and 100 μm, the mean bubble size is between 21 and 34 μm, the Sauter mean diameter (D32) is primarily between 50 and 300 μm, and the standard deviation (SD) is between 6 and 17 μm in 80 experiments. It provides a more accurate basis for the recommended manual method instability. The high variance values of the BSD indicate that the manual method has low stability and repeatability. The results of this study can be useful for further improvement of the reliability of c-TCD in detecting RLS. RESEARCH HIGHLIGHTS: This study provided the first detailed descriptions of the MBs size distribution in a flowing contrast agent by the microscopic shadow imaging technique. It reveals significant differences in the bubble size of manual foaming during repeated manipulations for each individual and between individuals.

Comparative evaluation of intracardiac, transesophageal, and transthoracic echocardiography in the assessment of patent foramen ovale: A retrospective single-center study

INTRODUCTION

Certain patent foramen ovale (PFO) characteristics, such as a large right-to-left shunt (RLS) or atrial septal aneurysm, identify patients who may receive the highest clinical benefit from percutaneous PFO closure. This study aimed to compare intracardiac echocardiography (ICE) with standard echocardiographic imaging in the evaluation of high-risk PFO characteristics and RLS severity in patients with PFO-associated stroke.

METHODS

We conducted a retrospective review of all patients aged ≥18 years who underwent percutaneous PFO closure for PFO-associated stroke and received all three ultrasound-based cardiac imaging modalities and had interpretable results (N = 51). We then compared RLS severity, high-risk PFO characteristics, and the proportion of patients with a higher likelihood of PFO-associated stroke by ICE versus transthoracic echocardiogram (TTE) and transesophageal echocardiogram (TEE).

RESULTS

The final cohort had a mean (±SE) age of 48.4 (±1.8) years and was predominantly female (58.8%). ICE was more likely to identify a large RLS versus TTE/TEE combined (66.7% vs. 45.1%; p = 0.03). The use of ICE resulted in significantly more patients being reclassified as having a higher likelihood of PFO-associated stroke (TTE vs. TEE vs. ICE: 10.4% vs. 14.6% vs. 25%; p = 0.03). A high-quality bubble study was found to be the single most important factor associated with identifying a larger RLS across all modalities (ρ [p]; TTE: 0.49 [<0.001], TEE: 0.60 [<0.001], ICE: 0.32 [0.02]). The presence of a hypermobile septum was associated with significantly greater RLS on ICE (ρ [p]: 0.3 [0.03]), especially with poor quality bubble studies (ρ [p]: 0.49 [0.02]).

CONCLUSION

In this observational study of patients with PFO-associated stroke, ICE detected a large RLS more frequently than TTE and TEE; and reclassified some patients as having a higher likelihood of PFO-associated stroke.

The Role of Transcranial Doppler in Detecting Patent Foramen Ovale

Air embolic signals detected in the intracranial arteries using transcranial Doppler after intravenous injection of agitated saline bubbles indicate right-to-left cardiac shunting. They prove that emboli from venous sites can bypass the lungs and flow to the intracranial arteries. The Valsalva maneuver immediately after an intravenous injection of agitated saline bubbles helps the air bubbles pass through the shunt. If the air embolic signal appears in the intracranial arteries without the Valsalva maneuver, the shunting is highly significant to the etiology of embolism. Transcranial Doppler to detect air embolic signals after intravenous injection of agitated saline bubbles may not be mandatory to diagnose and treat patent foramen ovale; however, as with echocardiography, transcranial Doppler is considered a noninvasive, convenient, and low-cost investigation. The test should be helpful to confirm the significance of the corresponding patent foramen ovale.

Association of Shunt Size and Long-Term Clinical Outcomes in Patients with Cryptogenic Ischemic Stroke and Patent Foramen Ovale on Medical Management

INTRODUCTION

Patent foramen ovale (PFO) is a potential source of cardiac embolism in cryptogenic ischemic stroke, but it may also be incidental. Right-to-left shunt (RLS) size may predict PFO-related stroke, but results have been controversial. In this cohort study of medically-managed PFO patients with cryptogenic stroke, we aimed to investigate the association of shunt size with recurrent stroke, mortality, newly detected atrial fibrillation (AF), and to identify predictors of recurrent stroke.

METHODS

Patients with cryptogenic stroke who screened positive for a RLS using a transcranial Doppler bubble study were included. Patients who underwent PFO closure were excluded. Subjects were divided into two groups: small (Spencer Grade 1, 2, or 3; n = 135) and large (Spencer Grade 4 or 5; n = 99) shunts. The primary outcome was risk of recurrent stroke, and the secondary outcomes were all-cause mortality and newly detected AF.

RESULTS

The study cohort included 234 cryptogenic stroke patients with medically-managed PFO. The mean age was 50.5 years, and 31.2% were female. The median period of follow-up was 348 (IQR 147-1096) days. The rate of recurrent ischemic stroke was higher in patients with large shunts than in those with small shunts (8.1% vs. 2.2%, p = 0.036). Multivariate analyses revealed that a large shunt was significantly associated with an increased risk of recurrent ischemic stroke [aOR 4.09 (95% CI 1.04-16.0), p = 0.043].

CONCLUSIONS

In our cohort of cryptogenic stroke patients with medically managed PFOs, those with large shunts were at a higher risk of recurrent stroke events, independently of RoPE score and left atrium diameter.

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.

The Prevalence of Microembolic Signals in Transcranial Doppler Sonography With Bubble Test in Acute Ischemic Stroke

OBJECTIVES

Transcranial Doppler ultrasound (TCD) is noninvasive and highly sensitive and specific for the diagnosis of patent foramen ovale (PFO). We evaluated the diagnostic implications of the TCD with a saline agitation test as a routine work-up for ischemic stroke patients.

METHODS

A TCD bubble study was performed in all consecutive ischemic stroke patients as a routine work-up. We evaluated the prevalence of microembolic signals (MES) for each stroke etiology and the optimal number of MES for predicting the PFO-attributable stroke.

RESULTS

Subjects (N = 499) with acute ischemic stroke were enrolled. A significant fraction of patients had MES during both normal respiration (5.7-44.4%) and the Valsalva maneuver (19.5-55.6%) across all stroke etiology categories. The optimal MES threshold for the diagnosis of PFO-attributable stroke confirmed by transesophageal echocardiography was 46 MES during the Valsalva maneuver (96% sensitivity and 95% specificity). Applying ≥46 MES during the Valsalva maneuver as a threshold effectively increased the ability to differentially diagnose PFO-attributable stroke from other etiologies. The number of MES during the Valsalva maneuver was negatively correlated with increasing age (r = -.108; P = .016).

CONCLUSIONS

A significant fraction of patients had right to left shunt across all Trial of ORG 10172 in Acute Stroke Treatment etiologies. A threshold number of MES facilitated the differential diagnosis of PFO-attributable stroke from other etiologies, and the optimal threshold was 46 MES during the Valsalva maneuver.

Estimation of patent foramen ovale size using transcranial Doppler ultrasound in patients with ischemic stroke

BACKGROUND AND PURPOSE

Patent foramen ovale (PFO)is associated with cryptogenic stroke, especially in young adults. Transcranial Doppler (TCD) ultrasound is used as a screening tool before transesophageal echocardiography (TEE). However, the use of Valsalva maneuver (VM) to identify a right-to-left-shunt underlies interindividual variability. Here, we aimed to assess whether a pressure-controlled standardization of VM is useful to estimate PFO size.

METHODS

We included patients aged 18-80 years with a PFO according to TEE. Subjects underwent TCD with microembolic signals (MES) counted under four pressure conditions (i.e., at rest, 15 mbar, 40 mbar, and maximum expiratory pressure). Findings were correlated with TEE-based PFO size. The predictive value of TCD at rest and VM-based TCD for PFO size estimation was assessed by stepwise multivariate linear regression models and multiple cross-tab-analyses.

RESULTS

We screened 203 subjects after a cerebrovascular event, of which 78 (48 males [61.5%], median age 55 years [22-80]) with PFO were included. We found an association between MES count and expiratory pressure (p < .001). Predefined MES count categories at TCD pressure conditions correlated significantly with PFO size measured by TEE. We propose a PFO size estimation model based on TCD at rest and under VM, which classified PFO size correctly in 64.1% with the highest accuracy for small PFOs.

CONCLUSION

Our data provide evidence that TCD with step-wise barometric standardization allows an estimation of PFO size with good accuracy. Though TCD will not replace TEE in future, this might be of clinical value in circumstances where TEE cannot be easily performed.

Novel robotic TCD ultrasound with bubbles versus standard care to detect right to left shunt: Study methods

BACKGROUND AND PURPOSE

Right to left shunt (RLS), from patent foramen ovale (PFO) or elsewhere, is a recognized risk factor for stroke. Current standard of care for RLS diagnosis includes transthoracic echocardiography (TTE) which is insensitive, transesophageal echocardiography (TEE) which is invasive, and transcranial Doppler (TCD) which has excellent sensitivity and specificity for RLS but is heavily operator dependent and expertise is scarce. The purpose of this study was to evaluate the RLS detection rate of a novel robotic-assisted TCD (ra-TCD) to standard of care diagnostic techniques, including TTE, TEE, and TCD.

METHODS

This is a multicenter, prospective, single-arm, nonsignificant risk device study of ra-TCD versus TTE for RLS diagnosis in adult patients who present with neurological signs and symptoms that include embolic stroke or transient ischemic attack on the differential diagnosis. Up to 150 subjects will be enrolled at up to seven centers considering the prevalence of PFO, suboptimal transtemporal windows, and potential dropouts. Enrolled patients will undergo ra-TCD supine and at 45° in a manner otherwise in line with standard of care TCD bubble technique. The enrolled patients will have undergone TTE, and optionally standard TCD and TEE, per usual care.

RESULTS

The primary efficacy endpoint is percent detection of RLS by ra-TCD compared against TTE. The primary safety endpoint is the incidence of device-related serious adverse events.

CONCLUSIONS

This is the first multicenter, prospective study evaluating the accuracy, feasibility, and safety of novel ra-TCD for the diagnosis of RLS as compared to standard of care diagnostics.

Right-to-left shunt detection using transforaminal insonation of the basilar artery

BACKGROUND AND PURPOSE

Investigation for patent foramen ovale (PFO) is warranted in patients with cryptogenic stroke (CS), as PFO closure is recommended in select CS patients for secondary stroke prevention. Transcranial Doppler (TCD) is noninvasive and has high sensitivity for PFO screening. However, 10% of the population has insufficient temporal bone windows to perform standard TCD monitoring of the middle cerebral arteries (MCAs). Prior reports showed similar diagnostic accuracy between the basilar artery and MCAs insonation. Our objective was to assess the accuracy of transforaminal insonation of the basilar artery (TIBA) in diagnosis of right-to-left shunt (RLS) in patients with inadequate temporal windows.

METHODS

We performed a retrospective, single-center, observational study of TIBA in patients with CS and inadequate temporal windows. We compared the PFO screening accuracy using TIBA versus echocardiogram, either transthoracic (TTE) or transesophageal echocardiogram (TEE).

RESULTS

Sixteen females and four males were included (mean age 63.2). All patients underwent TTE, 10 (50%) underwent gold-standard TEE. Nine patients had positive PFO with both TCD and echocardiogram. Two patients with negative echocardiogram had TCD-positive shunt. Three patients had PFO present on echocardiogram, whereas TCD was negative. Six patients had absent shunt with both TCD and echocardiogram. The sensitivity and specificity of TIBA for RLS detection were 75%, positive predictive value 82%, and negative predictive value 67%.

CONCLUSION

PFO screening accuracy using TIBA was 75%. Prospective evaluation of CS patients with TIBA and comparison to the gold-standard TEE should be performed to further guide clinical practice.

Cerebral Emboli Monitoring Using Transcranial Doppler Ultrasonography in Adults and Children: A Review of the Current Technology and Clinical Applications in the Perioperative and Intensive Care Setting

Transcranial Doppler (TCD) ultrasonography is the only noninvasive bedside technology for the detection and monitoring of cerebral embolism. TCD may identify patients at risk of acute and chronic neurologic injury from gaseous or solid emboli. Importantly, a window of opportunity for intervention-to eliminate the source of the emboli and thereby prevent subsequent development of a clinical or subclinical stroke-may be identified using TCD. In this review, we discuss the application of TCD sonography in the perioperative and intensive care setting in adults and children known to be at increased risk of cerebral embolism. The major challenge for evaluation of emboli, especially in children, is the need to establish the ground truth and define true emboli identified by TCD. This requires the development and validation of a predictive TCD emboli monitoring technique so that appropriately designed clinical studies intended to identify specific modifiable factors and develop potential strategies to reduce pathologic cerebral embolic burden can be performed.

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

A patent foramen ovale (PFO) is a common remnant of fetal circulation present in up to 25% of the worldwide adult population. Paradoxical embolism occurs when venous blood crosses the PFO into the arterial system, bypassing the pulmonary circulation. This allows for the direct passage of microemboli into cerebral blood vessels, increasing the risk of cryptogenic stroke. This review investigates the current diagnostic procedures used to detect and grade a PFO, including transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE) and transcranial Doppler (TCD). Only a few studies have directly compared the use of TTE with TCD for PFO detection but several have compared TTE and TCD independently against the clinical gold standard TOE. Known pitfalls of TTE and TCD are also discussed, including the difficulty of differentiating between intracardiac shunts and intrapulmonary shunts. This review also discusses methods to optimise imaging, such as performing an adequate Valsalva manoeuvre, the role of abdominal compression and the choice of the injection site for the contrast agent and how these may increase the diagnostic success of detecting a right-to-left shunt when prompted by a clinician.

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.

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.

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.

Recurrent Stroke after Transcatheter PFO Closure in Cryptogenic Stroke or Tia: Long-Term Follow-Up

Background

There are few data on the mechanism of recurrent neurological events after transcatheter closure of patent foramen ovale (PFO) in cryptogenic stroke or TIA.

Methods

We retrospectively reviewed PFO closure procedures for the secondary prevention of cryptogenic stroke/TIA performed between 1999 and 2014 in Bologna, Italy.

Results

Written questionnaires were completed by 402 patients. Mean follow-up was 7 ± 3 years. Stroke recurred in 3.2% (0.5/100 patients-year) and TIA in 2.7% (0.4/100 patients-year). Ninety-two percent of recurrent strokes were not cryptogenic. Recurrent stroke was noncardioembolic in 69% of patients, AF related in 15% of patients, device related in 1 patient, and cryptogenic in 1 patient. AF was diagnosed after the procedure in 21 patients (5.2%). Multivariate Cox's proportion hazard model identified age ≥ 55 years at the time of closure (OR 3.16, p=0.007) and RoPE score < 7 (OR 3.21, p=0.03) as predictors of recurrent neurological events.

Conclusion

Recurrent neurological events after PFO closure are rare, usually noncryptogenic and associated with conventional vascular risk factors or AF related. Patients older than 55 years of age and those with a RoPE score < 7 are likely to get less benefit from PFO closure. After transcatheter PFO closure, lifelong strict vascular risk factor control is warranted.

Comprehensive Ultrasound Assessment of the Craniocervical Circulation in Transient Global Amnesia

OBJECTIVES

Structural changes and metabolic stress have been reported on diffusion-weighted magnetic resonance imaging in the cornu ammonis 1 area of the hippocampus in patients with transient global amnesia (TGA), but a consensus on pathogenesis is still lacking. The aim of our study was to perform a comprehensive ultrasound analysis of the cerebrovascular circulation in our population of patients with TGA.

METHODS

One hundred patients with TGA and 50 age- and sex-matched control participants underwent ultrasound examinations of the cervicocranial circulation.

RESULTS

The most significant risk factor for TGA was arterial hypertension (P < .01). There were no significant atherosclerotic lesions on the large arteries of the neck (mean internal carotid artery stenosis ± SD, 28.7% ± 11.7%) or on the large intracerebral arteries (good structural and hemodynamic status; P > .05). Rarely detected microembolic signals or a right-left cardiopulmonary shunt excluded an emboligenic mechanism of TGA (P > .05). The internal jugular vein valves were incompetent in 54% of patients with TGA, and this condition was associated with an increased risk of TGA (odds ratio, 4.16; 95% confidence interval, 1.91-9.04). The mean values of the breath holding index and pulsatility index, as parameters of small-vessel function, were within normal ranges and without differences between the TGA and control groups (P > .05).

CONCLUSIONS

Our ultrasound examination did not detect significant structural atherosclerotic changes of cervicocranial arteries, and an emboligenic mechanism was excluded. Only a significant rise of blood pressure in TGA and significant valvular insufficiency of the internal jugular vein were established. New research should clarify whether these simultaneous functional circulatory changes have relevance for metabolic stress in the cornu ammonis of the hippocampus.

Percutaneous Closure of Patent Foramen Ovale in Patients With Migraine: The PREMIUM Trial

BACKGROUND

Migraine is a prevalent and disabling disorder. Patent foramen ovale (PFO) has been associated with migraine, but its role in the disorder remains poorly understood.

OBJECTIVES

This study examined the efficacy of percutaneous PFO closure as a therapy for migraine with or without aura.

METHODS

The PREMIUM (Prospective, Randomized Investigation to Evaluate Incidence of Headache Reduction in Subjects With Migraine and PFO Using the AMPLATZER PFO Occluder to Medical Management) was a double-blind study investigating migraine characteristics over 1 year in subjects randomized to medical therapy with a sham procedure (right heart catheterization) versus medical therapy and PFO closure with the Amplatzer PFO Occluder device (St. Jude Medical, St. Paul, Minnesota). Subjects had 6 to 14 days of migraine per month, had failed at least 3 migraine preventive medications, and had significant right-to-left shunt defined by transcranial Doppler. Primary endpoints were responder rate defined as 50% reduction in migraine attacks and adverse events. Secondary endpoints included reduction in migraine days and efficacy in patients with versus without aura.

RESULTS

Of 1,653 subjects consented, 230 were enrolled. There was no difference in responder rate in the PFO closure (45 of 117) versus control (33 of 103) groups. One serious adverse event (transient atrial fibrillation) occurred in 205 subjects who underwent PFO closure. Subjects in the PFO closure group had a significantly greater reduction in headache days (-3.4 vs. -2.0 days/month, p = 0.025). Complete migraine remission for 1 year occurred in 10 patients (8.5%) in the treatment group versus 1 (1%) in the control group (p = 0.01).

CONCLUSIONS

PFO closure did not meet the primary endpoint of reduction in responder rate in patients with frequent migraine. (Prospective, Randomized Investigation to Evaluate Incidence of Headache Reduction in Subjects With Migraine and PFO Using the AMPLATZER PFO Occluder to Medical Management [PREMIUM]; NCT00355056).

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.

Potential Role of Patent Foramen Ovale in Exacerbating Hypoxemia in Chronic Pulmonary Disease

Patent foramen ovale has been associated with multiple pulmonary diseases, such as pulmonary hypertension, platypnea-orthodeoxia syndrome, and chronic obstructive pulmonary disease. A connection between patent foramen ovale and chronic pulmonary disease was first described more than 2 decades ago in case reports associating patent foramen ovale with more severe hypoxemia than that expected based on the severity of the primary pulmonary disease. It has been suggested that patients with both chronic pulmonary disease and patent foramen ovale are subject to severe hypoxemia because of the right-to-left shunt. Furthermore, investigators have reported improved systemic oxygenation after patent foramen ovale closure in some patients with chronic pulmonary disease. This review focuses on the association between chronic pulmonary disease and patent foramen ovale and on the dynamics of a right-to-left shunt, and it considers the potential benefit of patent foramen ovale closure in patients who have hypoxemia that is excessive in relation to the degree of their pulmonary disease.

Patent foramen ovale and stroke in childhood: A systematic review of the literature

BACKGROUND

Stroke in association with a patent foramen ovale (PFO) may be due to paradoxical embolization via a right to left intracardiac shunt but the exact contribution of PFO to stroke or stroke recurrence in childhood remains unclear.

METHODS

To review the relationship of a PFO with stroke, and evaluate associated co-morbidities. An electronic database literature search of Pubmed, Cochrane and EMBASE was performed from January 2000-December 2014.

RESULTS

149 articles were retrieved, with overlap for diagnosis, management, treatment and outcome. 65 reports were utilized for the comprehensive review. Majority of childhood arterial ischemic stroke and transient ischemic attacks are associated with prothrombotic disorders or arteriopathy. Transthoracic echocardiography with a Valsalva maneuver is highly sensitive as a screening tool but may be falsely positive. Transthoracic echocardiography with color Doppler and a concurrent bubble contrast study are excellent for visualizing the atrial septum and PFO and identifying a right to left shunt. Current literature does not support PFO closure for cryptogenic stroke in young adults without an associated risk of thromboembolism.

CONCLUSIONS

High quality research in the pediatric population is lacking and most of the data is extrapolated from adults. Paradoxical embolism from a PFO as a cause of transient ischemic attack or stroke is a diagnosis of exclusion. PFO closure should be individualized based on significant shunting and risk factors such that maximum benefit is derived from the procedure. A young person with a PFO and stroke should be thoroughly investigated to rule out other etiologies.

Usefulness of Transcranial Doppler for Detecting Pulmonary Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia

The aim of this study was to assess transcranial Doppler (TCD) as a screening test for pulmonary arteriovenous malformation (PAVM) in patients with hereditary hemorrhagic telangiectasia (HHT). This retrospective study included suspected patients with HHT who were screened for PAVM with a TCD and a chest computed tomography (CT) study. The results of TCD and CT were compared to evaluate the usefulness of TCD for detecting PAVM. A TCD Spencer grade ≥3 was defined as positive for a significant right-to-left shunt (RLS). The diameter of the pulmonary arteries feeding the PAVM was measured by calipers from the CT study. In 86 subjects from 74 families with HHT, the sensitivity of TCD for identifying a PAVM at rest was 98% and post-Valsalva was 100%. Specificity was 58% and 35%, respectively, presumably due to pulmonary shunts too small to recognize on CT. Of the patients with HHT who were referred for embolization therapy for their PAVMs, all 20 had TCD grade ≥3. In patients who were diagnosed with a PAVM by chest CT, patients with TCD grade ≥5 had a significantly larger sum of artery diameters feeding the PAVMs compared to those with grade ≤4 (5.0 ± 3.2 mm vs 2.6 ± 1.9 mm, p = 0.01). In conclusion, a TCD examination for evaluating RLS is sensitive for identifying PAVM in patients with HHT and is useful in quantitating the degree of RLS flow. The sensitivity of the TCD examination makes it a useful screening test without radiation in HHT subjects to determine which patients need to undergo CT evaluation to identify PAVMs.

Transcranial Doppler is Complementary to Echocardiography for Detection and Risk Stratification of Patent Foramen Ovale

BACKGROUND

In patients with patent foramen ovale (PFO), strategies are needed to identify patients at higher risk, who might benefit from PFO closure.

METHODS

We studied the frequency of detection of a right-to-left shunt (RLS) using transesophageal echocardiography (TEE) among patients with cryptogenic stroke and transcranial Doppler (TCD) to detect RLS, and analyzed the prediction of recurrent stroke according to TCD shunt grade, by detection of RLS on TEE, and by atrial septal aneurysm or mobility.

RESULTS

Among 334 patients with TCD, 69.8% were female, with a mean (SD) age of 53 (14) years, with a median follow-up of 420 days. There were 284 cases with TCD and TEE; 54 (19%) had atrial septal aneurysm or mobility. Echocardiography failed to show a RLS in 43 (15.1%) of the patients who had TCD and TEE, even in some patients with high-grade shunts on TCD: 18 (42%) were grade 3 or higher on TCD. Survival free of stroke or transient ischemic attack was predicted significantly by TCD shunt grade < 2 (P = 0.028), shunt grade < 3 (P = 0.03), and shunt grade < 4 (P < 0.0001); this was attenuated by adjustment for risk factors in Cox regression (P = 0.08). Neither RLS on TEE (P = 0.47), or atrial septal aneurysm or mobility (P = 0.08), predicted events.

CONCLUSIONS

Our findings suggest that TCD might be more sensitive than TEE for detection of RLS, which misses some cases with substantial RLS, and might be valuable for prediction of recurrent stroke or transient ischemic attack in patients with PFO. TCD complements TEE for management of suspected paradoxical embolism.

Ischemic stroke patients with active malignancy or extracardiac shunts are more likely to have a right-to-left shunt found by TCD than echocardiogram

Although the association between patent foramen ovale and ischemic stroke is controversial, the evaluation for a right-to-left shunt remains part of the standard workup for cryptogenic stroke. Transthoracic and transesophageal echocardiogram (TTE and TEE) are the screening test and gold standard to evaluate for right-to-left shunt, respectively. Studies comparing TTE or TEE to transcranial Doppler (TCD) have shown that 15-25 % of patients test positive for right-to-left shunt on TCD but are negative on TTE or TEE. We sought to further explore this phenomenon in patients with recent ischemic stroke. Between 2011 and 2013, 109 ischemic stroke patients had both a TCD and TTE or TEE bubble study. We abstracted 12 comorbid medical conditions and stroke subtype according to the TOAST classification. The majority of TCD and TTE or TEE showed agreement on right-to-left shunt status (80/109, 73 %). Two percent (2/109) of patients were negative on TCD and positive on TTE or TEE, while 25 % (27/109) had a positive TCD and negative TTE or TEE (TCD+Echo-). The TCD+Echo- patients were more likely to have active malignancy and the delayed arrival of contrast bubbles than the remainder of the cohort (15 vs. 2 %, p = 0.032; 51 vs. 18 %, p = 0.001). Our results confirm previous reports that TCD is superior to echocardiography in the detection of right-to-left shunt. The TCD+Echo- patients were more likely to have active malignancy and findings suggestive of an extracardiac shunt. These results could lead to more comprehensive evaluation for occult malignancy or a pulmonary arteriovenous malformation, both potentially treatable etiologies of ischemic stroke.

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

OBJECTIVES

The aim of this meta-analysis was to determine the accuracy of transcranial Doppler (TCD) compared with transesophageal echocardiography (TEE) as the reference.

BACKGROUND

Right-to-left shunting (RLS), usually through a patent foramen ovale (PFO), has been associated with migraine, cryptogenic stroke, and hypoxemia. With emerging observational studies and clinical trials on the subject of PFO, there is a need for accurate diagnosis of PFO in patients with these conditions, and those being considered for transcatheter closure. Although a TEE bubble study is the current standard reference for diagnosing PFO, the TCD bubble study may be a preferable alternative test for RLS because of its high sensitivity and specificity, noninvasive nature, and low cost.

METHODS

A systematic review of Medline, the Cochrane Library, and Embase was done to look for all the prospective studies assessing intracardiac RLS using TCD compared with TEE as the reference; both tests were performed with a contrast agent and a maneuver to provoke RLS in all studies.

RESULTS

A total of 27 studies (29 comparisons) with 1,968 patients (mean age 47.8 ± 5.7 years; 51% male) fulfilled the inclusion criteria. The weighted mean sensitivity and specificity for TCD were 97% and 93%, respectively. Likewise, the positive and negative likelihood ratios were 13.51 and 0.04, respectively. When 10 microbubbles was used as the embolic cutoff for a positive TCD study, TCD produced a higher specificity compared with when 1 microbubble was used as the cutoff (p = 0.04); there was, however, no significant change in sensitivity (p = 0.29).

CONCLUSIONS

TCD is a reliable, noninvasive test with excellent diagnostic accuracies, making it a proficient test for detecting RLS. TCD can be used as a part of the stroke workup and for patients being considered for PFO closure. If knowledge of the precise anatomy is required, then TEE can be obtained before scheduling a patient for transcatheter PFO closure.

Patent foramen ovale in severe obstructive sleep apnea: clinical features and effects of closure

BACKGROUND

Patent foramen ovale (PFO) may contribute to nocturnal desaturation in patients with obstructive sleep apnea (OSA), and the effect of PFO closure in OSA is unknown. Our study tested the hypotheses that: (1) patients with severe OSA have a higher prevalence of PFO compared with healthy control subjects, (2) patients with severe OSA with clinically significant PFO experience more nocturnal desaturation than those without, and (3) PFO closure reduces nocturnal desaturation.

METHODS

Patients with severe OSA and healthy control subjects underwent contrast transthoracic echocardiography and transcranial Doppler to detect PFO and determine shunt size. A subgroup of patients with OSA with large shunts underwent percutaneous PFO closure. Polysomnography was performed at baseline and 1, 6, and 12 months postclosure.

RESULTS

One hundred patients with OSA (mean [SD] age, 52 [10] years; apnea-hypopnea index [AHI], 54 [18] events/h) and 50 control subjects (age, 52 [11] years; AHI, 2 [2] events/h) were studied. PFO prevalence was 43% in patients with OSA and 30% in control subjects ( P = .16). Large shunts were detected in 18% of patients with OSA and 6% of control subjects ( P = .049). Patients with OSA with clinically significant shunts had higher oxygen-desaturation index (ODI)/AHI ratios than patients without (ratio, 1.05 [0.27] vs 0.86 [0.26], P = .004). Six patients with OSA underwent PFO closure, which was not associated with a reduction in ODI (baseline, 48 [18]; 12 months, 51 [19] events/h; P = .92) or percentage of the night with arterial oxygen saturation , 90% (baseline, 23% [16%]; 12 months, 20% [22%]; P = .35).

CONCLUSIONS

Patients with severe OSA have a higher prevalence of PFO with large shunts compared with control subjects. The ODI/AHI ratio is increased in patients with OSA with clinically significant shunts. PFO closure does not reduce nocturnal desaturation.

The effect of patent foramen ovale closure on visual aura without headache or typical aura with migraine headache

OBJECTIVES

The aim of this study was to assess the prevalence of right-to-left (R to L) shunt in patients with visual aura and evaluate the effect of shunt closure on resolution of aura.

BACKGROUND

Right-to-left shunting is associated with migraine headache (MH) with aura. Some patients present with visual aura without headaches. It is unclear whether visual aura without headache is a form of migraine or a transient neurologic dysfunction.

METHODS

Of patients referred to the University of California, Los Angeles for suspected patent foramen ovale (PFO), 225 had visual aura with or without MH. Patients were assessed for a shunt and evaluated for MH and/or visual aura. They were divided into 3 groups: 1) visual aura associated with MH; 2) visual aura unrelated in time to MH; and 3) visual aura without MH. The frequency of R to L shunt was compared with a control group of 200 patients. Eighty patients underwent PFO closure. Residual shunts, MH, and visual aura were reassessed after 3 and 12 months.

RESULTS

The prevalence of R to L shunt in Groups A, B, and C was 96%, 72%, and 67%, respectively, versus 18% in the control group (p < 0.0001). The frequency of shunting was similar in Group B versus Group C, but much higher in all 3 groups compared with control subjects. Twelve months after PFO closure, symptoms of aura were resolved in 52%, 75%, and 80% of patients in Groups A, B, and C, respectively (p = NS).

CONCLUSIONS

The similar distribution of R to L shunting in all 3 patient groups and the correlation between PFO closure and improvement of aura suggests a similar pathophysiology between the presence of PFO and the visual aura phenomenon, whether or not headache is present in the symptom complex.

Paradoxical embolism, stroke and sclerotherapy

Sclerotherapy has been associated with 13 published cases of stroke since 1994. Four earlier reports implicated liquid sclerosants while nine recent cases have followed foam sclerotherapy. This adverse event represents a very rare complication of a very popular procedure. Ten of the 13 reported patients recovered completely with no long-term sequelae. A right-to-left shunt and in particular a patent foramen ovale (PFO) was the most consistent risk factor. Paradoxical gas emboli were observed in the brain-supplying or the intra-cranial arteries of five patients with an immediate onset of stroke after foam sclerotherapy. Paradoxical clot embolism was suspected in three patients with a delayed onset of stroke and concurrent venous thrombosis. In the remaining five cases, which included two cases with an immediate onset after liquid sclerotherapy, no specific cause was identified. Patients with a past history of cryptogenic stroke or a long life history of recurrent classic migraine attacks (with aura) have a higher risk of neurological adverse events and may benefit from preoperative screening and percutaneous closure of PFO.

The incidence of peripheral arterial embolism in association with a patent foramen ovale (right-to-left shunt)

Objectives

The aim of this study was to examine a cohort of patients who had suffered an arterial embolism to see whether a patent foramen ovale (PFO) was an identifiable cause.

Design

This study was conducted in two parts; a retrospective limb involving an audit of patient records over a period of 10 years, and a prospective limb including selected patients from that audit to search for a PFO using an agitated saline test with transcranial Doppler ultrasound monitoring of the anterior cerebral artery. Data on patients with peripheral vascular disease were collected using a structured questionnaire.

Setting

A clinical vascular department. All patients were seen in the vascular outpatients clinic.

Participants

Patients who had been identified from a retrospective search based on the headline diagnosis of arterial embolus. Collected data on the 71 patients revealed that 75% had predisposing factors for DVT, 70% were male smokers, and 84.4% had a significant past history of vascular symptoms.

Main outcome measures

Whether or not patients identified as having a possible PFO actually had one on objective testing with transcranial Doppler assessment of the cerebral circulation with an agitated saline solution.

Results

Fifteen patients who were suspected of having a PFO were selected from these 71 patients; 12 of these were found to have no PFO on testing, and three had already undergone a percutaneous PFO closure.

Conclusion

The incidence of a PFO in this small study group is no higher than that found in the general population (3/15, 20%). There was high prevalence of male smokers with associated predisposing factors leading to a DVT.

Sensitivity of transcranial Doppler versus intracardiac echocardiography in the detection of right-to-left shunt

OBJECTIVES

The purpose of this study was to understand the reason for variation in the sensitivity of different methods of detecting right-to-left shunts (RLS).

BACKGROUND

Patent foramen ovale (PFO) is implicated in the pathogenesis of cryptogenic stroke, decompression illness, and migraine headaches. Intravenous agitated saline injections with tomographic imaging (transthoracic, transesophageal, and intracardiac echocardiography) has been used for detecting intracardiac shunts. Some patients with a high clinical suspicion of PFO have inconclusive echocardiographic study results. Transcranial Doppler (TCD) is an alternative method for detecting RLS that is not dependent on tomographic imaging.

METHODS

Thirty-eight consecutive patients who were undergoing PFO closure had simultaneous transcranial Doppler and intracardiac echocardiography performed. Agitated saline injections were performed at rest, with Valsalva maneuver, and with forced expiration into a manometer to 40 mm Hg before and after closure, as well as 3 or more months after closure. Right atrial pressures were measured in the periprocedural period, and RLS were graded according to standard methods during these maneuvers.

RESULTS

Right atrial pressures were significantly higher with Valsalva maneuver compared with rest (before closure 21.6 +/- 11.9 mm Hg vs. 6.6 +/- 2.6 mm Hg, p < 0.001; after closure 28.4 +/- 13.9 mm Hg vs. 6.8 +/- 2.6 mm Hg, p < 0.001) and with manometer compared with Valsalva maneuver (before closure 38.7 +/- 6.6 mm Hg vs. 21.6 +/- 11.9 mm Hg, p < 0.001; after closure 44.0 +/- 9.5 mm Hg vs. 28.4 +/- 13.9 mm Hg, p < 0.001). Intracardiac echocardiography underestimated shunting in 34% of patients with Valsalva maneuver or manometer after closure compared with TCD.

CONCLUSIONS

Transcranial Doppler with immediate feedback provided by forced expiration against a manometer to 40 mm Hg is more sensitive than echocardiographic imaging for the detection of RLS. These observations have significant implications for determining the incidence of RLS in patients with stroke or migraine.

Intracranial embolism characteristics in PFO patients: a comparison between positive and negative PFO by transesophageal echocardiography: the rule of nine

BACKGROUND AND PURPOSE

Patent foramen ovale (PFO) can be diagnosed by contrast-enhanced transcranial Doppler (cTCD), but no definitive criteria exist to correlate the results obtained from cTCD with diagnoses of PFO obtained by contrast-enhanced transesophageal echocardiography (cTEE). The aim of the present study was to analyze markers in the positive RLS by cTCD that confirm the PFO by cTEE.

METHODS

Twenty-six stroke patients who had previously submitted to cTEE, 16 with PFO (PFO group) and 10 without PFO (no-PFO group), were evaluated for three markers based on a positive cTCD test. The number of microembolic signs (MES), the latency time (LT) to the first MES and the duration time (DT) of MES were evaluated to look for a difference between the PFO and no-PFO group.

RESULTS

The PFO group had higher MES (80.9+/-124.5 vs. 10.2+/-25.6, p<0.001), shorter LT (12.5+/-6.6 vs. 16.2+/-5.1, p=0.02) and longer DT (21.4+/-17.4 vs. 11.7+/-12.5, p=0.013) compared with the no-PFO group. Considering only MCA tests with more than 9 MES and LT shorter than 9s, 30% of patients from the PFO group had positive tests compared with no patients from the no-PFO group. This cutoff demonstrates a specificity and positive predictive value of 100%.

CONCLUSIONS

The rule of nine (>9 MES and LT <9s) for cTCD can be considered a marker for PFO diagnosis by cTEE.