Contrast Transthoracic Echocardiography Using 50% Glucose as a Contrast Agent for Screening of a Patent Foramen Ovale

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.

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.

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.

Supradiaphragmatic central venous catheter malposition detection using the parasternal long-axis echocardiographic view and dextrose 50% contrast solution: A pilot study

Background

Contrast-enhanced ultrasonography (CEUS) using saline was studied to detect supradiaphragmatic central venous catheter malposition. Commonly used echocardiographic views are apical 4-chamber (A4c) and subcostal views. However, this standard method is not feasible in certain situations. We explored the feasibility of the right ventricle inflow parasternal long axis (RVI-PLAX) echocardiographic view and dextrose 50% (D50%) contrast solution for detecting supradiaphragmatic central venous catheter malposition.

Method

This pilot study screened 60 patients who underwent ultrasound-guided supradiaphragmatic central venous catheter insertion. We compared the investigators' guidewire's J-tip detection, D50% rapid atrial swirl sign (RASS) findings on the RVI-PLAX view and the central venous catheter tip on chest radiograph. We also compared the mean capillary blood sugar level before and after the 5 ml D50% flush.

Results

No guidewire J-tips were detected from the RVI-PLAX view. The first and second investigators' diagnosis of central venous catheter malposition detected on RVI-PLAX CEUS achieved an almost perfect agreement (κ = 1.0 (95% confidence interval (CI): 0.90 to 1.0), p < .0001). The RVI-PLAX CEUS was not able to detect two central venous catheter malpositions (one atrial malposition and one left brachiocephalic vein venous catheter malposition). The capillary blood sugar was significantly elevated (8.96 mmol/L vs. 9.75 mmol/L) after D50% flush (p < 0.005) with no complications reported within 30 minutes after the D50% flush.

Conclusion

RVI-PLAX view should not be used for guidewire detection. CEUS using D50% and RVI-PLAX view are potentially useful tools in detecting central venous catheter malposition. Further studies comparing them with conventional methods are needed.

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.

Agitated Saline Contrast Echocardiography in the Identification of Intra- and Extracardiac Shunts: Connecting the Dots

Agitated saline contrast studies are an essential component of contemporary echocardiography. Agitated saline contrast plays a critical role in the elucidation of intracardiac versus intrapulmonary shunting and can have major therapeutic implications, particularly in light of the evolution of percutaneous treatment options for atrial septal defects or a patent foramen ovale. Despite their perceived simplicity, however, there are numerous pitfalls of these investigations that can occur during their performance and interpretation. As such, the authors review the "bubble study" in identifying intracardiac and extracardiac shunts, including the history of its development, the physics and physiology of contrast enhancement, how to optimally perform and interpret an agitated saline contrast study, and its safety in unique populations.

Cough maneuver is superior to Valsalva maneuver for detecting mild-extent right-to-left shunt

Objective: The purpose of this study was to explore the different provocative maneuvers in detecting right-to-left shunt during contrast transthoracic echocardiography (cTTE). Methods: We evaluated 378 patients for right-to-left shunt detection by cTTE at the quiet respiration, during Valsalva maneuver (blowing into a face mask connected to a sphygmomanometer at 40 mmHg for 10 s), and during cough maneuver, performed in random order, and the degree of right-to-left shunt as the number of microbubbles in the left atrium per frame after each provocative maneuver was recorded. Results: The detection rates of right-to-left shunt for quiet respiration, Valsalva maneuver, and cough maneuver were 16%, 33%, and 38%, respectively (p < .001). The detection rate for cough maneuver was significantly higher than that for Valsalva maneuver (p < .001). There was no significant difference between Valsalva maneuver and cough maneuver in terms of detecting moderate- or severe-extent right-to-left shunt (p > .05), but cough maneuver was significantly better than Valsalva maneuver at detecting mild-extent right-to-left shunt (p = .001). Conclusions: Cough maneuver is an effective alternative to Valsalva maneuver, with a higher detection rate for mild-extent right-to-left shunt during cTTE, maybe due to its own mechanical characteristics.