Diagnosis and quantification of patent foramen ovale. Which is the reference technique? Simultaneous study with transcranial Doppler, transthoracic and transesophageal echocardiography

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Synchronous multimode ultrasound for assessing right-to-left shunt: a prospective clinical study

Background

Right-to-left shunt (RLS) is associated with several conditions and causes morbidity. In this study, we aimed to evaluate the effectiveness of synchronous multimode ultrasonography in detecting RLS.

Methods

We prospectively enrolled 423 patients with high clinical suspicion of RLS and divided them into the contrast transcranial Doppler (cTCD) group and synchronous multimode ultrasound group, in which both cTCD and contrast transthoracic echocardiography (cTTE) were performed during the same process of contrast-enhanced ultrasound imaging. The simultaneous test results were compared with those of cTCD alone.

Results

The positive rates of grade II (22.0%:10.0%) and III (12.7%:10.8%) shunts and the total positive rate (82.1748%) in the synchronous multimode ultrasound group were higher than those in the cTCD alone group. Among patients with RLS grade I in the synchronous multimode ultrasound group, 23 had RLS grade I in cTCD but grade 0 in synchronous cTTE, whereas four had grade I in cTCD but grade 0 in synchronous cTTE. Among patients with RLS grade II in the synchronous multimode ultrasound group, 28 had RLS grade I in cTCD but grade II in synchronous cTTE. Among patients with RLS grade III in the synchronous multimode ultrasound group, four had RLS grade I in cTCD but grade III in synchronous cTTE. Synchronous multimode ultrasound had a sensitivity of 87.5% and specificity of 60.6% in the patent foramen ovale (PFO) diagnosis. Binary logistic regression analyses showed that age (odds ratio [OR] = 1.041) and risk of paradoxical embolism score ≥ 7 (OR = 7.798) were risk factors for stroke recurrence, whereas antiplatelets (OR = 0.590) and PFO closure with antiplatelets (OR = 0.109) were protective factors.

Conclusion

Synchronous multimodal ultrasound significantly improves the detection rate and test efficiency, quantifies RLS more accurately, and reduces testing risks and medical costs. We conclude that synchronous multimodal ultrasound has significant potential for clinical applications.

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.

Echocardiographic characteristics of transcatheter closure of patent foramen ovale with mallow biodegradable occluder: A single-center, phase III clinical study

Background

Transcatheter occlusion of patent foramen ovale (PFO) has become a recognized treatment option for high-risk PFO-related diseases. However, traditional metal occluders have some disadvantages, such as permanent retention in the body, abrasion of tissues, and obstruction of access to the left side of the heart for interventional procedures. With biodegradable occluders that release non-toxic degradation products and are absorbable by the body, the risk of long-term complications could be greatly reduced. The experimental results of using a PFO-degradable occluder in beagle dogs in early stages, independently developed by Shanghai Mallow Medical Instrument Co., Ltd., showed that the occluding umbrella disc network was degraded 6 months after occlusion. The occluder also showed good memory, biocompatibility, and mechanical properties.

Methods

As one of the multi-center research units, this prospective Phase III clinical trial study included 16 patients with PFO-related complications who were treated with a degradable occluder. The follow-up period lasted for 12 months to analyze the echocardiographic characteristics and procedural feasibility.

Results

The immediate success rate of the procedure was 100% with no serious complications. Postoperative color Doppler transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) at 12 months showed that one patient with atrial septal aneurysm (ASA) had a residual shunt at the edge of the occluder, and contrast transcranial Doppler (cTCD) showed that all patients were grade I or 0 right-to-left shunts (RLS), indicating that the occlusion success rate was 100%. The occluder gradually degraded after the procedure, particularly when the umbrella disc structure became vague, and the size of the occluder decreased significantly 6 months after occlusion.

Conclusions

PFO closure with a Mallow degradable occluder has a high plugging success rate, is safe and effective, and has no serious complications. However, for PFO closure with special anatomical features, further research with a larger sample size is required. TTE can dynamically, conveniently, and accurately observe the entire degradation process of the occluder.

Clinical Trial Registration

ChiCTR1900024036.

Comparison of right-to-left shunt characteristics in cryptogenic embolic ischemic stroke and non-cardioembolic ischemic stroke

BACKGROUND

Patent foramen ovale (PFO) has been considered a potential mechanism of embolic stroke of undetermined origin.

OBJECTIVE

The aim of the present study was to identify the features of the right-to-left shunt (RLS) in patients with undetermined embolic ischemic stroke and compare them with those of patients with non-cardioembolic ischemic stroke.

METHODS

A retrospective study was conducted with 168 patients with stroke and RLS separated into the following two groups: the undetermined embolic stroke group (UES group) and non-cardioembolic stroke group (NCES group). All patients were assessed by transcranial Doppler to evaluate the presence and quantification of microembolic signals (MES) at rest and under Valsalva maneuver.

RESULTS

Of all patients evaluated in the current study, 96 were included in the UES group and 72 in the NCES group. In the UES group, 65 patients had RLS with ≥10 MES (67.7%), which was higher than that observed in the NCES group (51.4%, p=0.038). According to the moment of the cardiac cycle, 75 patients (78.1%) in the UES group had a positive test at rest compared to 42 (58.3%) in the NCES group (p=0.007).

CONCLUSIONS

The current study demonstrated that almost 70% of patients with undetermined embolic stroke and PFO presented a large RLS and more than 75% had RLS at rest. These findings suggest that the size of the shunt should be taken into account when evaluating whether PFO could be a possible mechanism underlying cryptogenic stroke.

Multidisciplinary assessment of patients with ischemic stroke, the structure of a stroke team, and first Egyptian experience in adults undergoing transcatheter PFO closure for PFO-related stroke

Background

Patent foramen ovale closure in the setting of stroke was debatable until the recent data from the long-term follow-up of multiple randomized control trials. These recent data have led to increase the number of the procedure worldwide.

To our knowledge, there was no previous formal structured program in Egypt between cardiologists and neurologists for investigation and management of patients with cryptogenic stroke.

The first Egyptian-dedicated stroke team was created in two large tertiary centers with collaboration between cardiologists, dedicated cardiac imagers, and neurologists for investigation and management of patients with cryptogenic stroke.

Results

Sixty-three patients with cryptogenic stroke were identified from a total of 520 patients admitted to the stroke units between 2016 and 2019. Twenty-five patients had a proven PFO-related stroke. Three patients were referred for surgical closure, 19 patients underwent transcatheter PFO closure, and procedural success was met in 18 patients (94.7%). We did not experience any major procedure-related complication. Complete closure was achieved in 83.3% of patients at 6 months. One patient had a single attack TIA within the first 3 months after device closure; one patient had a device-related thrombosis; both were managed successfully.

Conclusion

Our initial experience in collaboration between cardiologist and neurologist with the establishment of a dedicated cryptogenic stroke team added significantly to the management of patients with stroke.

The results of the first Egyptian cohort who underwent transcatheter PFO closure demonstrated procedural feasibility, safety, and efficacy with very low incidence of major complications.

A nationwide program is needed to reduce the ischemic stroke disease burden and the risk of recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00139-8.

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.

The Presence of Patent Foramen Ovale in the Superior Type of Sinus Venosus Atrial Septal Defect

Background: The superior type of sinus venosus atrial septal defect (SVASD) is a rare form of the atrial septal defect (ASD) in which the upper part of the atrial septum does not exist. The presence of other cardiac anomalies such as anomalous pulmonary venous connections has been reported in this type of congenital heart disease. This study aimed to assess the presence of the patent foramen ovale (PFO) in patients with the superior type of SVASD.

Methods: This retrospective case-control study on 387 patients, consisting of 187 patients with a definite SVASD and 200 patients with problems other than the ASD, was conducted in Rajaie Cardiovascular Medical and Research Center between February 2005 and July 2014. Seven patients with inadequate data were excluded from the analysis. The presence/absence of the PFO was also evaluated in the case and control groups.

Results: The analyses were performed on 182 male and 198 female patients at a mean age of 39.07±14.41 and 51.01±15.80 years in the case and control groups, respectively. The PFO was significantly more frequent in the patients with the superior type of SVASD than in those without the condition (P<0.001). The persistence of the left superior vena cava was seen in 34 out of 180 patients with SVASD and in 1 out of 200 patients without the condition (18.9% vs 0.5%; P<0.001).

Conclusion: This study was the first to highlight the coexistence of the PFO and the superior type of SVASD. Physiological, genetic, or fetal factors may play an important role in the association between the PFO and the SVASD.

Modified Method of Contrast Transthoracic Echocardiography for the Diagnosis of Patent Foramen Ovale

Purpose

To compare the sensitivity and specificity of modified and traditional methods of contrast echocardiography of the right portion of the heart in patients with a suspicion of patent foramen ovale (PFO).

Methods

The study population consisted of 506 patients with high clinical suspicion of PFO. The traditional Valsalva maneuver consists of expiration against a closed glottis after a full inspiration. A modified Valsalva maneuver was performed with a handmade pressure monitoring device, which measured pressure during performance of the Valsalva maneuver. Modified and traditional methods of contrast echocardiography were performed among all patients. Contrast transesophageal echocardiography (TEE) was regarded as the gold standard.

Results

A total of 279 patients with PFO were confirmed by TEE. 259 cases (sensitivity: 92.83%) were detected by a modified method of contrast echocardiography of the right portion of the heart, while 234 cases were detected using the traditional method (sensitivity: 83.87%). The sensitivity of modified contrast echocardiography of the right portion of the heart was significantly higher than that of the traditional method (92.83% vs. 83.87%, P=0.001). However, there was no significant difference in the specificity of the two methods for the diagnosis of PFO (97.35% vs. 96.03%, P=0.431). Additionally, the results of semiquantitative evaluation of PFO using modified method failed to show a more positive rate than shown by the traditional method (Z=−1.782, P=0.075).

Conclusions

Modified contrast echocardiography of the right portion of the heart yielded a higher sensitivity than the traditional method, which contributed to the diagnosis of cardiac PFO. The research was a part of a register study (https://register.clinicaltrials.gov/ ClinicalTrials ID: NCT02777359).

A comparison of contrast transthoracic echocardiography and contrast transcranial Doppler in cryptogenic stroke patients with patent foramen ovale

OBJECTIVE

In recent years, increasing attention has been paid to cryptogenic stroke (CS) caused by the patent foramen ovale (PFO). This study aims to compare contrast transthoracic echocardiography (cTTE) and contrast transcranial Doppler (cTCD) to determine whether cTTE is more suitable and reliable than cTCD for clinical use.

METHODS

From March 2017 to May 2018, patients who suffered from migraines, stroke, hypomnesis, or asymptomatic stroke found casually were included in our study. Patients with CS were semirandomly divided into two groups (cTTE and cTCD) according to the date of the outpatient visit. Patients with either of the examination above found positive were selected to finish transesophageal echocardiography (TEE).

RESULTS

In our study, the sensitivities of group cTTE positive (group cTTE+) and group cTCD positive (group cTCD+) did not have any statistical difference (89% vs. 80%, p = 0.236). Focusing on group cTCD+, we discovered that the semiquantitative shunt grading was not correlated with whether a PFO was present or not (p = 0.194). However, once the PFO has been diagnosed, the shunt grading was shown to be related to the width of the gaps (p = 0.032, p_deviation  = 0.03).

CONCLUSION

Both cTTE and the cTCD can be used for preliminary PFO findings. The semiquantitative shunt grading of cTCD and cTTE can suggest the size of the PFO and the next course of treatment. The cTTE may be more significant to a safe PFO (a PFO does not have right-to-left shunts, RLSs). Combining cTTE and TEE could help diagnose PFO and assess CS risk.

Comparison of Different Contrast Agents in Detecting Cardiac Right-to-Left Shunt in Patients with a Patent Foramen Ovale during Contrast-Transthoracic Echocardiography

The aim of this study is to evaluate the ability of two different contrast agents to detect cardiac right-to-left shunting in patients with a patent foramen ovale during contrast transthoracic echocardiography and transesophageal echocardiography. Eighty-four patients who had migraines or experienced cryptogenic stroke were prospectively enrolled. Contrast echocardiography of the right portion of the heart was performed using an injection of either (i) 8 ml of agitated saline, 1 ml of blood, and 1 ml of air (ASB) or (ii) 4 ml of vitamin B₆ and 6 ml of sodium bicarbonate solution (VSBS). All patients underwent contrast echocardiography with different contrast agents successively before undergoing transesophageal echocardiography. The diagnostic sensitivity of VSBS and ASB for cardiac shunting diagnosis was 94.23% and 78.85%, respectively. The diagnostic sensitivity in the VSBS group was significantly higher than that in the ASB group (χ² = 5.283, P = 0.022). The observed semiquantitative shunt grading suggests that the positive rate in the VSBS group was higher than that in the ASB group (Z = −1.998, P = 0.046). The use of vitamin B₆ and sodium bicarbonate solution as a TTE contrast agent yielded a high sensitivity compared with ASB. However, further trials with large sample size are required to confirm this finding.

Atrial dyssynchrony and left atrial stiffness are risk markers for cryptogenic stroke in patients with patent foramen ovale

OBJECTIVE

The clinical and echocardiographic parameters associated with the risk predictors of cryptogenic stroke (CS) in patients with patent foramen ovale (PFO) still diverse and with a great debate. We hypothesized that left atrial stiffness (LASt) and atrial dyssynchrony may increase the risk of CS in patients with PFO.

METHODS

A total of 129 consecutive patients presented without clinical reasoning of stroke were recruited. Transesophageal echocardiographic assessment was performed to investigate the presence of PFO. PFO was identified in 52% (group I) and absent in 48% (group II). Utilizing speckle-tracking imaging LASt and atrial dyssynchrony was evaluated among patients with PFO (group I) vs those without PFO (group II).

RESULTS

LASt was significantly increased in group I patients compared with group II (P < .001). Likewise patients with PFO had a significant LA dyssynchrony compared with those in group II (P < .001). Interatrial dyssynchrony and left atrial dyssynchrony were correlated with LASt (r = .47 and 0.51, respectively; P < .001). Cardiac arrhythmias were significantly encountered in group I patients (at presentation and with Holter monitoring) P < .001. Besides significantly increase in atrial dyssynchrony and in LASt in patients with arrhythmias compared with those without (P < .001). ROC analysis revealed that LASt index ≥ 0.61 and LA dyssynchrony ≥ 23.5 predicts cardiac arrhythmias in CS patients with PFO with (AUC: 0.85 and 0.87, respectively, P < .001).

CONCLUSION

In conclusion, we demonstrated that LASt and atrial dyssynchrony might be risk markers of cryptogenic stroke in patients with 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.

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.

Transthoracic contrast echocardiography using vitamin B6 and sodium bicarbonate as contrast agents for the diagnosis of patent foramen ovale

To evaluate the utility of transthoracic contrast echocardiography (cTTE) using vitamin B6 and sodium bicarbonate as contrast agents for diagnosing right-to-left shunt (RLS) caused by patent foramen ovale (PFO) compared to that of transesophageal echocardiography (TEE). We investigated 125 patients admitted to our neurology department with unexplained cerebral infarction and migraine. All patients underwent cTTE using vitamin B6 and sodium bicarbonate as contrast agents, after which they underwent transthoracic echocardiography. The Doppler signal was recorded during the Valsalva maneuver, and TEE examinations were performed. The feasibility, diagnostic sensitivity, and safety of cTTE and TEE for PFO recognition were compared. Evidence of PFO was found in 49 (39.20%) patients with cTTE, more than were detected with TEE (39, 31.20%) (χ²=5.0625, P=0.0244). cTTE had a sensitivity of 92.31% and a specificity of 84.88% for diagnosing PFO, showing high concordance with TEE for PFO recognition (κ=0.72). Further, results of a semi-quantitative evaluation of PFO-RLS by cTTE were better than those with TEE (Z=-2.011, P=0.044). No significant adverse reaction was discovered during cTTE examination. cTTE using vitamin B6 and sodium bicarbonate as contrast agents has relatively good sensitivity and specificity for diagnosing RLS caused by PFO when compared with those for TEE. Using vitamin B6 and sodium bicarbonate as contrast agents to perform cTTE is recommended for detecting and diagnosing the PFO due to its simplicity, non-invasive character, low cost, and high feasibility.

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.

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.

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.

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.”

Detection of Right-to-Left Cardiac Shunt in the Absence of Transcranial Acoustic Bone

PURPOSE

Paradoxical thrombotic embolism via right-to-left cardiac shunt (RLS) is a risk factor of cryptogenic ischemic stroke. Transtemporal Doppler (TTD) is a valid method used in the detection of patent foramen ovale (PFO). Temporal acoustic bone windows are missing with increasing age and in some younger subjects. We studied prospectively whether Doppler ultrasound of the cervical arteries (submandibular internal carotid artery [ICA] and vertebral artery [VA]) is an alternative, when compared to TTD, in the detection and quantification of PFO.

MATERIAL AND METHODS

A total of 94 patients with sufficient temporal bone windows suffering from recent ischemic stroke underwent TTD and ICA (n = 51) or TTD and VA (n = 43). After injection of microbubbles, the numbers of artificial high-intensity signals (HITS) were recorded at rest and after Valsalva maneuver.

RESULTS

For 47 patients in the ICA group, an RLS was found at rest in 23 patients and after Valsalva in 28 patients. At rest, sensitivity was 100%, specificity 96%, positive predictive value (ppv) 95.6%, and negative predictive value (npv) 100%. After Valsalva, sensitivity was 100%, specificity 95%, ppv 96.4%, npv 100%. For 43 patients in the VA group an RLS was found at rest in 14 patients and after Valsalva in 19 patients. At rest, sensitivity was 71.4%, specificity 100%, ppv 100%, and npv 87.8%. After Valsalva, 94.4%, 96%, 94.4%, and 96%, respectively. Pearson's correlations of the number of HITS between TTD and ICA and between TTD and VA were highly significant.

CONCLUSIONS

When transcranial acoustic bone windows are missing, Doppler ultrasound of the cervical submandibular ICA and VAs are valid screening methods to detect RLS due to a PFO.

Transient cerebral ischemia in an elderly patient with patent foramen ovale and atrial septal aneurysm

Cerebrovascular disease is one of the most common causes of cerebrovascular morbidity and mortality in developed countries; up to 40% of acute ischemic strokes in young adults are cryptogenic in nature – that is, no cause is determined. However, in more than half of these patients, patent foramen ovale (PFO) is seen along with an increased incidence of atrial septal aneurysm (ASA). The following is a report of an interesting case: a 68-year-old man with ASA and transient cerebral ischemia. Transesophageal echocardiography (TEE) showed the presence of ASA; a test with microbubbles derived from a mixture of air and saline or colloids pointed out a shunt on the foramen ovale following Valsalva’s maneuver. The patient underwent percutaneous transcatheter closure of the interatrial communication by an interventional cardiologist. TEE and transcranial Doppler or TEE with the microbubbles test are the recommended methods for detecting and quantifying intracardiac shunts, both at rest and following Valsalva’s maneuver. In patients following the first event of transient ischemic attack, and without clinical and anatomical risk factors (such as the presence of ASA, PFO, and basal shunt), pharmacological treatment with antiplatelets or anticoagulants is closely recommended. On the contrary, in patients following the first event of transient ischemic attack, or a recurrent event during antiplatelet treatment, the percutaneous closure of PFO is recommended.

The RoPE Score and Right-to-Left Shunt Severity by Transcranial Doppler in the CODICIA Study

BACKGROUND

For patients with cryptogenic stroke (CS) and patent foramen ovale (PFO), it is unknown whether the magnitude of right-to-left shunt (RLSh) measured by contrast transcranial Doppler (c-TCD) is correlated with the likelihood an identified PFO is related to CS as determined by the Risk of Paradoxical Embolism (RoPE) score. Additionally, for patients with CS, it is unknown whether PFO assessment by c-TCD is more sensitive for identifying RLSh compared with transesophageal echocardiography (TEE). Our aim was to determine the significance of RLSh grade by c-TCD in patients with PFO and CS.

METHODS

We evaluated patients with CS who had RLSh quantified by c-TCD in the Multicenter Study into RLSh in Cryptogenic Stroke (CODICIA) to determine whether there is an association between c-TCD shunt grade and the RoPE Score. For patients who underwent c-TCD and TEE, we determined whether there is agreement in identifying and grading RLSh between these two modalities.

RESULTS

The RoPE score predicted the presence versus the absence of RLSh documented by c-TCD (c-statistic = 0.66). For patients with documented RLSh by c-TCD, shunt severity was correlated with increasing RoPE score (rank correlation (r) = 0.15, p = 0.01). Among 293 patients who had both c-TCD and TEE performed, c-TCD was more sensitive (98.7%) for detecting RLSh. Of the 97 patients with no PFO identified on TEE, 28 (29%) had a large amount of RLSh seen on c-TCD.

CONCLUSIONS

For patients with CS, severity of RLSh by c-TCD is positively correlated with the RoPE score, indicating that this technique for shunt grading identifies patients more likely to have pathogenic rather than incidental PFOs. c-TCD is also more sensitive in detecting RLSh than TEE. These findings suggest an important role for c-TCD in the evaluation of PFO in the setting of CS.

Significance of Patent Foramen Ovale in Patients with GOLD Stage II Chronic Obstructive Pulmonary Disease (COPD)

Background: Patent foramen ovale (PFO) is a common finding in adults. A PFO is associated with right to left shunting but its importance in the aetiology of hypoxia in early COPD remains uncertain, although it has not proved possible to demonstrate a role for PFOs in the aetiology of hypoxia in patients with Global Initiative for chronic Obstructive Lung Disease (GOLD) stage III/IV disease. We compared the characteristics of GOLD stage II patients with or without a PFO and assessed its impact on exercise performance. Methods: In 22 GOLD stage II COPD patients we measured exercise performance, arterial oxygen tension and lung function and used contrast transcranial Doppler ultrasonography (TCD) to assess the presence of a PFO. Patients (n=20) underwent TCD measurements during incremental cycle ergometry with respiratory pressures measured using an esophageal balloon catheter (n=13). Results:Twelve individuals (54%) had a PFO. Patients with a PFO were more hypoxic; mean(SD) partial pressure of oxygen in arterial blood (PaO₂)10.2(1.1) kilopascals (kPa) vs. 11.7(0.9)kPa (p<0.01), but the presence of a PFO was not associated with reduced exercise performance either on cycle ergometry or a 6 Minute Walk Test (6MWT). A strong relationship was noted between the esophageal pressure swing (P_SwingEs) and the degree of shunting observed during exercise (r=0.7; p<0.001). Conclusions:The presence of a PFO in GOLD stage II COPD patients does not appear to influence exercise performance despite increased right-to-left shunting.

Update on cardiac imaging techniques 2012

Cardiac imaging is one of the basic pillars of modern cardiology. The potential list of scenarios where cardiac imaging techniques can provide relevant information is simply endless so it is impossible to include all relevant new features of cardiac imaging published in the literature in 2012 in the limited format of a single article. We summarize the year's most relevant news on cardiac imaging, highlighting the ongoing development of myocardial deformation and 3-dimensional echocardiography techniques and the increasing use of magnetic resonance imaging and computed tomography in daily clinical practice.

Two-dimensional echocardiography using second harmonic imaging for the diagnosis of intracardiac right-to-left shunt: a meta-analysis of prospective studies

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 being considered for transcatheter closure. While transesophageal echo (TEE) bubble study is the current standard reference for diagnosing PFO, transthoracic echo with second harmonic imaging (TTE-HI) may be a preferable screening test for RLS due to its high accuracy and non-invasiveness. The aim of this meta-analysis was to determine the accuracy of TTE-HI compared to TEE as the reference. A systematic review of Medline, Cochrane and Embase was done for all the prospective studies assessing for intracardiac RLS using TTE-HI compared to TEE as the reference; both TTE-HI and TEE were performed with a contrast agent and a maneuver to provoke RLS in all studies. A total of 15 studies with 1995 patients fulfilled the inclusion criteria. The weighted mean sensitivity and specificity for TTE-HI were 91 and 93 % respectively. Likewise, the positive and negative likelihood ratios were 13.52 and 0.13 respectively. TTE-HI is a reliable, non-invasive test with proficient diagnostic accuracies. The high sensitivity and specificity of TTE-HI make it a useful initial screening test for RLS. If the precise anatomy is required, then TEE can be obtained before scheduling a patient for transcatheter PFO closure.

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.

Safety of ultrasound contrast agents in patients with known or suspected cardiac shunts

Contrast-enhanced ultrasound imaging is a radiation-free diagnostic tool that uses biocompatible ultrasound contrast agents (UCAs) to improve image clarity. UCAs, which do not contain dye, often salvage "technically difficult" ultrasound scans, increasing the accuracy and reliability of a front-line ultrasound diagnosis, reducing unnecessary downstream testing, lowering overall health care costs, changing therapy, and improving patient care. Two UCAs currently are approved and regulated by the US Food and Drug Administration. They have favorable safety profiles and risk/benefit ratios in adult and pediatric populations, including compromised patients with severe cardiovascular diseases. Nevertheless, these UCAs are contraindicated in patients with known or suspected right-to-left, bidirectional, or transient right-to-left cardiac shunts. These patients, who constitute 10% to 35% of the general population, typically receive no UCAs when they undergo echocardiography. If their echocardiographic images are suboptimal, they may receive inappropriate diagnosis and treatment, or they may be referred for additional diagnostic testing, including radiation-based procedures that increase their lifetime risk for cancer or procedures that use contrast agents containing dye, which may increase the risk for kidney damage. An exhaustive review of current peer-reviewed research demonstrated no scientific basis for the UCA contraindication in patients with known or suspected cardiac shunts. Initial safety concerns were based on limited rodent data and speculation related to macroaggregated albumin microspheres, a radioactive nuclear imaging agent with different physical and chemical properties and no relation to UCAs. Radioactive macroaggregated albumin is not contraindicated in adult or pediatric patients with cardiac shunts and is routinely used in these populations. In conclusion, the International Contrast Ultrasound Society Board recommends removal of the contraindication to further the public interest in safe, reliable, radiation-free diagnostic imaging options for patients with known or suspected cardiac shunts and to reduce their need for unnecessary downstream testing.

[State of the art: new developments in cardiac imaging]

Cardiac imaging continues to reveal new anatomical and functional insights into heart disease. In echocardiography, both transesophageal and transthoracic three-dimensional imaging have been fully developed and optimized, and the value of the techniques that have increased our understanding of cardiac mechanics and ventricular function is well established. At the same time, the healthcare industry has released new devices onto the market which, although they are easier to use, have limitations that restrict their use for routine assessment. Tomography's diagnostic and prognostic value in coronary artery disease continues to increase while radiation exposure becomes progressively lower. With cardiac magnetic resonance imaging, myocardial injury and recovery in ischemic heart disease and following acute coronary syndrome can be monitored in exquisite detail. The emergence of new combined tomographic and gamma camera techniques, exclusively developed for nuclear cardiology, have improved the quality of investigations and reduced radiation exposure. The hybrid or fusion images produced by combining different techniques, such as nuclear cardiology techniques and tomography, promise an exciting future.