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

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

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

Diagnostic value of contrast-enhanced ultrasonography for patent foramen ovale detection

Background

Patent foramen ovale (PFO) has been associated with migraine, cryptogenic stroke (CS), and hypoxemia. However, which examination method is most reliable remains controversial. This study sought to investigate the diagnostic value of contrast-enhanced ultrasonography (cU), including contrast-enhanced transcranial Doppler (cTCD), contrast transthoracic echocardiography (cTTE), and contrast transesophageal echocardiography (cTEE), for PFO; and to determine the best diagnostic strategy.

Methods

This retrospective observational study included a total of 147 consecutive patients suspected PFO at The First Hospital of Shanxi Medical University between October 2019 and January 2022. The patients also underwent cTCD, cTTE, and cTEE examinations. The standard for the diagnosis of PFO was confirmation of the presence of PFO by color Doppler flow signals or contrast microbubbles (MBs) passing through the foramen ovale.

Results

A total of 123 patients were diagnosed with PFO and 24 patients without PFO during the study period. The detectable rates of cTCD, cTTE, and cTEE were 120 (97.56%), 110 (89.43%), and 121 (98.37%), respectively. The sensitivity between cTCD and cTEE for PFO were comparable [97.56%, 95% confidence interval (CI): 92.5% to 99.4% vs. 98.37%, 95% CI: 93.7% to 99.7%; P>0.99], and the sensitivity of both were higher than that of cTTE (89.43%, 95% CI: 82.3% to 94.0%; P=0.02 and P=0.001, respectively). In addition, the specificity of cTEE for PFO was significantly higher than that of cTCD (100%, 95% CI: 82.3% to 100.0% vs. 75.00%, 95% CI: 53.0% to 89.4%; P<0.001) and cTTE (100%, 95% CI: 82.3% to 100.0% vs. 75.00%, 95% CI: 53.0% to 89.4%; P<0.001). Further, the semi-quantitative classification ability of cTCD for PFO with right-to-left shunt (RLS) was significantly higher than that of cTTE and cTEE (P=0.02 and P<0.001, respectively), and that of cTTE was significantly higher than that of cTEE (P=0.01). The Spearman analysis showed that the degree of RLS was positively correlated with the inner diameter of the PFO (r=0.695, P<0.001).

Conclusions

The combination of cTCD and cTEE may provide a favorable strategy for the diagnosis of PFO.

The predictive value of abnormal electrocardiogram for patent foramen ovale: A retrospective study

BACKGROUND AND HYPOTHESIS

The objective of this study was to identify the characteristics of electrocardiogram (ECG) in adult patients with patent foramen ovale (PFO) and to analyze the predictive value of the characteristics of ECG for PFO in adult patients.

METHODS

Retrospectively, 267 patients who had undergone ECG, transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) with agitated saline contrast echocardiography in our hospital, were recruited continuously from January 2021 to March 2023. Electrocardiographs were analyzed to investigate the presence of right bundle branch block (RBBB) and crochetage R wave.

RESULTS

The ratio of crochetage R wave in inferior leads in patients with PFO was 45.3% and 21.2% without PFO. There were 17 (6.4%) patients with coexistence of crochetage R wave and RBBB, including 13 (6.5%) patients with PFO and four (6.1%) patients without PFO. The accuracies of TTE, crochetage R wave, and RBBB were 0.637, 0.535, and 0.314, respectively. A combination of crochetage R wave and RBBB demonstrated a sensitivity of 0.507 and a specificity of 0.758. When TTE, crochetage R wave, and RBBB were combined, the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 0.712, 0.801, 0.439, 0.813, and 0.420, respectively. Logistic regression analysis revealed a correlation between PFO and the presence of crochetage R wave (odds ratio [OR]: 3.073, 95% confidence interval [CI]: 1.601-5.899, p < 0.001), and also a combination between crochetage R wave and RBBB (OR: 3.220, 95% CI: 1.720-6.028, p < 0.001).

CONCLUSIONS

Crochetage R wave in ECG was associated with PFO. Crochetage R wave, especially combined with RBBB and TTE, may be helpful in the early detection of patients with PFO.

Contrast-enhanced transcranial doppler versus contrast transthoracic echocardiography for right-to-left shunt diagnosis

RLS can be diagnosed using US, CT angiography, and right heart catheterization. However, most reliable diagnostic modality remains undetermined. c-TCD was more sensitive than c-TTE in the diagnosis of RLS. This was true especially for the detection of provoked shunts or mild shunts. c-TCD can be used as the preferred screening method for RLS.

Predictive value of transesophageal echocardiography combined with contrast transthoracic echocardiography for embolic stroke of undetermined source

OBJECTIVE

In this study, we aimed to assess the predictive value of transesophageal echocardiography (TEE) combined with contrast transthoracic echocardiography (cTTE) for embolic stroke of undetermined source (ESUS).

METHODS

A total of 52 patients with ESUS were examined by TEE and cTTE. The detection rate of patent foramen ovale (PFO) and right-to-left shunt (RLS) grade were compared in patients with ESUS between cTTE alone and cTTE combined with TEE. The Risk of Paradoxical Embolism (RoPE) score, PFO diameter, and PFO length of patients with PFO-associated ESUS and non-PFO-associated ESUS were compared by cTTE alone and cTTE combined with TEE. The receiver operating characteristic (ROC) curve was utilized to determine the effect of RoPE score and PFO diameter on patients with PFO-associated ESUS.

RESULTS

The positive rate of PFO detected by cTTE alone (46.15%) was lower than that detected by cTTE combined with TEE (69.23%). The proportion of patients with RLS grade I + II + III detected by cTTE combined with TEE (69.23%) was higher than that detected by cTTE alone (46.15%). Both the RoPE score and PFO diameter were significantly greater in the patients with PFO-associated ESUS than in the patients with non-PFO-associated ESUS (p < .05). The combination of RoPE score and PFO diameter had the largest area under the ROC curve (AUC = 0.875), which was larger than the AUC alone of RoPE score (AUC = 0.819) and PFO diameter (AUC = 0.783) (p < .05).

CONCLUSION

The combination of cTTE and TEE is helpful to the diagnosis of ESUS patients caused by PFO and to judge the degree of RLS.

Diagnostic Accuracy of Transthoracic Echocardiography With Contrast for Detection of Right-to-Left Shunt: A Systematic Review and Meta-analysis

BACKGROUND

The clinical utility of transthoracic echocardiography with contrast (TTE-C) for detection of right-to-left shunt (RLS) remains unknown. In this meta-analysis we evaluated the accuracy of TTE-C for RLS diagnosis compared with transesophageal echocardiography (TEE) as the reference standard.

METHODS

A systematic review and meta-analysis was performed using a search of MEDLINE, EMBASE, PubMed, and Cochrane library databases. Studies that were included provided data to assess sensitivity and specificity of TTE-C compared with TEE for RLS detection.

RESULTS

A total of 35 studies, involving 4209 patients, were analyzed. The average patient age was 49.1 ± 11.2 years and 53.9% were male. For RLS detection in the entire cohort, TTE-C sensitivity was 73% (95% confidence interval [CI], 66%-80%) and specificity was 94% (95% CI, 92%-96%). The sensitivity of TTE-C was 80% (95% CI, 74%-86%) in studies published in 2000 or later compared with 51% (95% CI, 36%-65%) in those published before 2000. In studies that used harmonic imaging, TTE-C sensitivity was 82% (95% CI, 77%-87%) and specificity was 95% (95% CI, 93%-97%). Among those with patent foramen ovale closure indications, TTE-C sensitivity was 74% (95% CI, 59%-89%) and specificity was 98% (95% CI, 95%-100%). In patients in whom RLS was diagnosed using a guideline-suggested 3 cardiac cycle cutoff, TTE-C sensitivity was 75% (95% CI, 66%-83%) and specificity was 94% (95% CI, 92%-97%). Provocative manoeuvres increased sensitivity by approximately 40%.

CONCLUSIONS

TTE-C offers excellent specificity and moderate sensitivity for RLS diagnosis compared with TEE, and it might therefore serve as an initial screening modality for selected patients with a high likelihood of having RLS and for indications for treatment.

A Nomogram for the Prediction of Cessation of Migraine Among Patients With Patent Foramen Ovale After Percutaneous Closure

Objective: This study aimed to develop and validate a nomogram to predict cessation of patent foramen ovale (PFO) patients with migraine headache after percutaneous closure.

Methods: A total of 247 eligible patients with PFO and migraine after percutaneous closure between May, 2016 and May, 2018 were divided into a development cohort (n = 149) and a validation cohort (n = 98). The primary end point was cessation of migraine at follow-up of 1 year after the procedure measured by the Migraine Disability Assessment Score (MIDAS). In the development cohort, the LASSO regression was used data dimension reduction. A multivariable logistic regression analysis was used to develop the predicting nomogram. The performance of the nomogram was assessed by concordance index (C-index), calibration and clinical usefulness. The results were validated in the validation cohort.

Results: Migraine with aura, history of antiplatelet, and the right-to-left shunt (RLS) at rest were identified as significant predictors based on the analysis of multivariate logistic regression. The nomogram incorporating these variables showed good calibration and discrimination in the development cohort with C-index of 0.906 (95% CI: 0.847–0.965), which was confirmed using the validation cohort with C-index of 0.827 (95% CI: 0.751–0.903). The nomogram showed good agreement between prediction by nomogram and actual observation. Furthermore, the decision curve indicated that the novel nomogram was clinically useful.

Conclusion: The novel nomogram showed favorable predictive accuracy for cessation of migraine among patients with PFO after percutaneous closure and might provide constructive guidance in clinical decision making.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

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.

Microbubble Formulations: Synthesis, Stability, Modeling and Biomedical Applications

Microbubbles are increasingly being used in biomedical applications such as ultrasonic imaging and targeted drug delivery. Microbubbles typically range from 0.1 to 10 µm in size and consist of a protective shell made of lipids or proteins. The shell encapsulates a gaseous core containing gases such as oxygen, sulfur hexafluoride or perfluorocarbons. This review is a consolidated account of information available in the literature on research related to microbubbles. Efforts have been made to present an overview of microbubble synthesis techniques; microbubble stability; microbubbles as contrast agents in ultrasonic imaging and drug delivery vehicles; and side effects related to microbubble administration in humans. Developments related to the modeling of microbubble dissolution and stability are also discussed.