Comparison of transthoracic echocardiography with second harmonic imaging with transesophageal echocardiography in the detection of right to left shunts

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.

Transcranial Doppler ultrasound: Clinical applications from neurological to cardiological setting

Transcranial Doppler (TCD) ultrasonography is a rapid, noninvasive, real-time, and low-cost imaging technique. It is performed with a low-frequency (2 MHz) probe in order to evaluate the cerebral blood flow (CBF) and its pathological alterations, through specific acoustic windows. In the recent years, TCD use has been expanded across many clinical settings. Actually, the most widespread indication for TCD exam is represented by the diagnosis of paradoxical embolism, due to patent foramen ovale, in young patients with cryptogenic stroke. In addition, TCD has also found useful applications in neurological care setting, including the following: cerebral vasospasm following acute subarachnoid hemorrhage, brain trauma, cerebrovascular atherosclerosis, and evaluation of CBF and cerebral autoregulation after an ischemic stroke event. The present review aimed to describe the most recent evidences of TCD utilization from neurological to cardiological setting.

A Review of Transcatheter Closure of Patent Foramen Ovale

A patent foramen ovale (PFO) is a common variant in cardiac anatomy found in 25% to 30% of U.S. adults. While PFOs are a normal part of fetal development and commonly seen in asymptomatic adults, they have been implicated in a variety of pathophysiologic conditions. The most clinically important of these is paradoxical embolization of venous thrombus resulting in stroke or systemic embolism. Various devices can be used to close PFOs via a transcatheter approach to prevent recurrent stroke. Data regarding the safety and effectiveness of these devices is rapidly evolving, with recent long-term results suggesting efficacy in preventing secondary stroke in carefully selected patients. This review discusses historical data on PFO occurrence and treatment, a risk score that can assess the likelihood of a stroke being attributable to a PFO, a variety of other conditions that may be linked to PFOs, and current research regarding the role transcatheter closure plays in their treatment.

[Paradoxical embolism: Myth or reality?]

Paradoxical embolism should be suspected in front of a clinical phenomenon of thromboembolism associated with an anatomical right-to-left shunt. Others potential cardiac sources of thromboembolism must be ruled out. Strokes constitute the most frequent clinical manifestations of paradoxical embolism. Right-to-left left shunts are in connection with intracardiac defects (atrial septal defect and patent foramen ovale) or pulmonary arteriovenous malformations. The probability that a discovered PFO is stroke-related can be evaluated by a score. Therapeutic approaches for secondary prevention of recurrent stroke include antithrombotic and/or percutaneous treatments. The choice strategy begins to be clearer with the recent results of randomized controlled studies.

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.

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.

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.”

Importance of an adequately performed Valsalva maneuver for detecting a right-to-left shunt indicating foramen ovale reopening

OBJECTIVES

The purpose of this study was to investigate the importance of an adequately performed Valsalva maneuver for detecting a right-to-left shunt indicating reopening of the functional closure of the foramen ovale.

METHODS

We prospectively analyzed 260 patients (102 women and 158 men; mean age ± SD, 41 ± 19 years; range, 13-83 years) who underwent transesophageal echocardiography and agitated saline injection. Two-dimensional echocardiography, color Doppler imaging, and microbubbles were used to detect right-to-left shunts, and the Valsalva maneuver was performed to determine whether the functional closure of the foramen ovale had reopened.

RESULTS

Transesophageal echocardiography with color Doppler imaging identified a patent foramen ovale in 20 patients: 18 patients with a patent foramen ovale had left-to-right shunts, and 2 patients with atrial septal defects had bidirectional shunts. Both patients with atrial septal defects showed right-to-left shunt microbubbles without and with the Valsalva maneuver, whereas all 18 patients with a patent foramen ovale showed right-to-left shunt microbubbles only after the Valsalva maneuver. Foramen ovale reopening was identified by transesophageal echocardiography in an additional 40 patients with no shunt during rest on agitated saline injection and in whom the right-to-left shunt appeared only after the Valsalva maneuver. The Valsalva maneuver could cause an atrial septal swing, and its sensitivity and specificity were 100%.

CONCLUSIONS

An adequately performed Valsalva maneuver is important for detecting a right-to-left shunt indicating reopening of the functional closure of the foramen ovale.

[Detection of an intrapulmonary shunt in patients with liver cirrhosis through contrast-enhanced transcranial Doppler. A study of prevalence, pattern characterization, and diagnostic validity]

INTRODUCTION

Intrapulmonary vascular dilatations (IPVD) are considered a complication of cirrhosis. The technique of choice for their diagnosis is contrast-enhanced echocardiography (CEE). The aim of this study was to determine the usefulness of contrast-enhanced transcranial Doppler (CETD) in the diagnosis of IPVD.

METHOD

We consecutively included patients evaluated for liver transplantation. A cross-sectional study was conducted. The investigator interpreting CETD was blind to the results of the gold standard (CEE). The accuracy of the diagnostic test was evaluated through sensitivity, specificity, positive and negative predictive values, and likelihood ratio.

RESULTS

CETD (n=43) showed a right-to-left shunt in 23 patients (62.2%): 4 early, 2 indeterminate and 17 late. Nineteen (51,4%) cases were classified as IPVD. With CEE (n=37), 10 procedures (27%) were negative for shunt, 27 (73%) were positive, and 21 (56.8%) were compatible with IPVD. Patients with and without IPVD showed no differences in age, sex, etiology, severity, or MELD score, independently of the diagnostic test. In the diagnostic validity study (n=37) of CETD versus CEE, the AUC for diagnostic yield was 0.813% (95%CI: 0.666-0.959; P=.001), sensitivity was 76.2% (95%CI: 54.9-89.4) and specificity was 90% (95%CI: 63.9-96.5). The positive likelihood ratio was 6.095.

CONCLUSIONS

We found a high prevalence of IPVD in candidates for liver transplantation. When a late right-to-left shunt with recirculation is observed, CETD has a high probability of detecting IPVD, with few false-positive results. Because this technique has not previously been described in this indication, similar studies are needed for comparison.

Patent Foramen Ovale in Recreational and Professional Divers: An Important and Largely Unrecognized Problem

Patent foramen ovale (PFO) is associated with an increased risk of decompression sickness (DCS) in divers that results from a paradoxical embolization of nitrogen bubbles. The number of scuba divers worldwide is estimated in the millions, and the prevalence of PFO is 25%-30% in adults. It is interesting that despite these numbers, many important issues regarding optimal screening, risk stratification, and management strategy still remain to be resolved. Recently published data suggest the possible effectiveness of both PFO closure and conservative diving measures in preventing arterial gas embolization. This review aims to introduce the basic principles of physiology and the pathophysiology of bubble formation and DCS, summarize the current literature on PFO and diving, and review the possibilities of diagnostic workup and management.

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.

How to Understand Patent Foramen Ovale Clinical Significance: Part I

Patent foramen ovale (PFO) is a remnant of fetal circulation commonly found in healthy population. However, a large number of clinical conditions have been linked to PFO, the most important being ischemic strokes of undetermined cause (cryptogenic strokes) and migraine, especially migraine with aura. Coexistent atrial septal aneurysm, size of PFO, degree of the shunt, shunt at rest, pelvic deep vein thrombosis, and prothrombotic states (G20210A prothrombin gene mutation, Factor V Leiden mutation, MTHFR: C677T, basal homocystine, recent surgery, trauma, or use of contraceptives) could enhance stroke risk in subjects with PFO. Owing to the complexity of this issue, for any individual presenting with a PFO, particularly in the setting of cryptogenic stroke, it is not clear whether the PFO is pathogenically related to the neurological event or an incidental finding. Thus, a heart-brain team, which individually plans the best strategy, in accordance with neuroimaging findings and anatomical characteristics of PFO, is strongly recommended. In the first part of this review, we discuss the embryologic and anatomic features of PFO, the diagnostic techniques for its identification and evaluation, and the relationship between PFO and neurological syndromes. A special attention is made to provide some key points, useful in a daily clinical practice, which summarize how better we understand PFO clinical significance

Diagnostic value of transthoracic echocardiography for patent foramen ovale: a meta-analysis

As a non-invasive and convenient modality, transthoracic echocardiography (TTE) has been widely recommended for the diagnosis of patent foramen ovale (PFO). In this study our aim was to systematically review the diagnostic accuracy of TTE in detection of PFO. We conducted comprehensive searches in PubMed, Embase and the Cochrane Library to the end of September 1, 2012. Sixteen studies comprising 1831 patients were included in the meta-analysis. The quality of reported studies was modest. The summary sensitivity and specificity of TTE in diagnosis of PFO were 88% (95% confidence interval [CI], 79-94) and 97% (95% CI, 92-99), respectively. The positive likelihood ratio was 27.1 (95% CI, 11.2-65.1), and the negative likelihood ratio was 0.12 (95% CI, 0.07-0.22). The summary diagnostic odds ratio was 221 (95% CI, 95-518). Subgroup analyses suggested that age and initial disease may affect the accuracy of TTE in detection of PFO. The meta-analysis suggested that TTE is a test with high sensitivity and specificity in detection of PFO, but it may not be appropriate for screening for PFO in all patients, especially patients with a small right-left shunt.

Determination of the optimum number of cardiac cycles to differentiate intra-pulmonary shunt and patent foramen ovale by saline contrast two- and three-dimensional echocardiography

INTRODUCTION

Patent foramen ovale (PFO) and intra-pulmonary shunt (IPS) are potential causes of stroke. The most optimum cardiac cycle cutoff for bubbles to appear in the left heart on saline contrast transthoracic echocardiography (TTE) as criteria to differentiate the 2 entities is unknown.

METHODS

Ninety-five adult patients had saline contrast transesophageal echocardiography (TEE), two-dimensional (2D) and 3DTTE. Sensitivity and specificity of each cardiac cycle as cutoff to differentiate a PFO and IPS were obtained.

RESULTS

Transesophageal echocardiography showed IPS in 28 and PFO in 15 patients. If bubbles appeared in the left heart within the first 4 cardiac cycles (the 4th cardiac cycle rule) as compared to alternate cutoffs, a PFO was most accurately diagnosed by both 2D and 3DTTE. Bubbles appearing at or after the 5th cardiac cycle most accurately determined an IPS. 3D versus 2DTTE had a trend for a higher sensitivity (61% vs. 36%, P = 0.06), but similar specificity (94% vs. 91%) for IPS. Accuracy of 3DTTE was 84% and 2DTTE was 75% (P = 0.08) for IPS. For PFO, 2DTTE sensitivity (87%) and specificity (98%) did not differ (P = NS) from that of 3DTTE sensitivity (73%) and specificity (100%).

CONCLUSIONS

This study demonstrates for the first time that the 4th cardiac cycle rule differentiates PFO and IPS most optimally by 2D and 3DTTE. 3DTTE appears to have higher sensitivity for diagnosing IPS. These data suggest that 3DTTE is preferable when IPS is to be diagnosed. Both methods are similar for diagnosing PFO.

[Low sensitivity of the echocardiograph compared with contrast transcranial Doppler in right-to-left shunt]

BACKGROUND

Contrast transcranial Doppler (c-TCD) has a high sensitivity for detecting right-to-left shunt (RLS), and is probably higher than transthoracic echocardiography (TTE) and comparable with transesophageal echocardiography (TEE).

OBJECTIVE

To evaluate the accuracy of echocardiography (TTE and TEE) to detect RLS compared to c-TCD.

MATERIAL AND METHODS

Observational study of patients <55 years old with cerebral ischaemia of undetermined origin (2007-2009). All underwent c-TCD monitoring to detect RLS, at rest and after Valsalva manoeuvre (VM). The TTE and TEE were performed when indicated by our cerebrovascular protocol. The accuracy of TTE and TEE for detecting RLS was calculated by comparing them with c-TCD.

RESULTS

A total of 115 patients with c-TCD, mean age 43.3 (SD 10.3) years, 51.3% male. The TTE was performed in 102, and TEE in 81, patients. RLS detection was higher with c-TCD than with TTE (67.6% vs. 22.5%, P=.001) or TEE (77.8% vs. 53.1%, P=.001). The TTE, compared with c-TCD after MV showed: sensitivity 31.8%, specificity 96.9%, positive predictive value (PPV) 95.6%, negative predictive value (NPV) 40.5% and accuracy 52.9% to detect RLS. TEE, compared with c-TCD after MV showed: sensitivity 63.4%, specificity 83.3%, PPV 93%, NPV 39.4% and accuracy 67.9%. The accuracy of TTE and TEE improved when they were compared with c-TCD at rest.

CONCLUSIONS

TTE and TEE show a considerable number of false negatives for RLS detection. Clinical studies should consider the c-TCD as the best technique to diagnose RLS when a paradoxical embolism is suspected.

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

INTRODUCTION AND OBJECTIVES

Patent foramen ovale (PFO) is the most common cause of cryptogenic stroke in patients younger than 55. Transesophageal echocardiography (TEE) has been accepted as the reference diagnostic technique. The purpose of this study was to compare the accuracy of transthoracic echocardiography (TTE), TEE and transcranial Doppler (TCD) in the diagnosis and quantification of patent foramen ovale.

METHODS

We studied 134 patients prospectively. Simultaneous TTE with TCD and TEE with TCD were performed, using agitated saline solution to detect right to left shunt.

RESULTS

In 93 patients diagnosed with PFO, the shunt was visualized at baseline by TCD in 69% of cases, by TTE in 74% and by TEE in 58%. The Valsalva maneuver produced a similar improvement in shunt diagnosis with all 3 techniques (26%-28%). TTE and TCD showed higher sensitivity (100% vs 97%; non significant difference) than TEE in the diagnosis of PFO (86%; P<.001). TCD performed during TEE did not diagnose 12 (13%) shunts previously diagnosed during TTE. Similarly, TEE underestimated shunt severity.

CONCLUSIONS

TTE enables adequate diagnosis and quantification of PFO. TEE is less sensitive and tends to underestimate the severity of the shunt.

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.

Patent foramen ovale in cerebral infarction

Recent studies support the hypothesis of a close aetiological and pathogenic association between the presence of patent foramen ovale (PFO) and cryptogenic stroke. The therapeutic options currently used in the treatment of these patients range from standard antiaggregation and standard-dose anticoagulation to the percutaneous occlusion of the PFO. The use or recommendation of treatment is based both on clinical risk factors associated with PFO, such as age, detection of states of hypercoagulability and previous history of stroke, and on the risks associated to right-to-left shunt (RLSh) and PFO, such as the size of PFO, magnitude of RLSh and the presence of atrial septal aneurysm (ASA). However, there is currently no consensus regarding the most suitable treatment and it is surprising to observe the widespread use of certain therapeutic approaches which are not supported by clinical evidence. In this revision, we analyse the relevance of PFO in cryptogenic stroke, consider the main evidence available for determining the best management of these patients and make diagnostic and therapeutic management recommendations.

Prevalence of patent foramen ovale determined by transesophageal echocardiography in patients with cryptogenic stroke aged 55 years or older. Same as younger patients?

INTRODUCTION AND OBJECTIVES

To investigate the relationship between patent foramen ovale and cryptogenic stroke in patients aged > or =55 years.

METHODS

This prospective study determined the presence of patent foramen ovale and atrial septal aneurysm using transesophageal echocardiography in 262 consecutive patients with a diagnosis of probable cryptogenic stroke. Data from 44 patients aged > or =55 years with cryptogenic stroke (Group A) were compared with those from two other groups: 194 patients aged <55 years with cryptogenic stroke (Group B) and 24 control patients aged > or =55 years with stroke of known origin, namely grade III-V aortic atheromatosis (Group C).

RESULTS

The frequency of patent foramen ovale in Group A was similar to that in Group B (38% vs. 36%; P=.85) but significantly higher than that in Group C (38% vs. 8%; P=.029). The frequency of patent foramen ovale with concomitant atrial septal aneurysm was significantly higher in the study group (Group A) than in the control Group C (18% vs. 0; P=.039) and non-significantly higher than in Group B (18% vs. 11%; P=.11).

CONCLUSIONS

The frequency of patent foramen ovale alone or in association with atrial septal aneurysm in patients with cryptogenic stroke aged > or =55 years was similar to that in those aged <55 years, but higher than that in patients aged > or =55 years with stroke of atherosclerotic origin. These data suggest that paradoxical embolism could be a cause of stroke in both age groups.

Enhanced detection of patent foramen ovale by systematic transthoracic saline contrast echocardiography

OBJECTIVE

We aimed to evaluate the effectiveness of transthoracic saline contrast echocardiography (TSCE) in detecting patent foramen ovale (PFO).

BACKGROUND

Transesophageal echocardiography (TEE) is semi-invasive and not ideal for PFO screening.

METHODS

112 patients (48 males, 46 ± 14 years) with suspected PFO received intravenous agitated-saline contrast at rest and stress (strain and release phases of Valsalva maneuver and coughing). The presence of interatrial shunting was defined as >5 bubbles appearing in the left heart within 3 cardiac cycles. The stage of the maneuver at which interatrial shunting occurred was recorded. The TSCE findings were validated by TEE.

RESULTS

TEE identified PFO in 45% of patients. The sensitivities of TSCE in detecting PFO at rest, during strain and release of Valsalva maneuver, and coughing were 12.0%, 38.0%, 80.0% and 94.0% respectively (each p<0.05 when compared to previous stage). Specificities were similar and >95% for all stages. Moreover, the release phase of the maneuver improved the diagnostic accuracy [defined as (number of true positives+true negatives) divided by total in sample] with incremental value over the preceding strain phase (89.2 vs. 70.5%, p<0.001).

CONCLUSIONS

Patent foramen ovale can be identified confidently with proper conduct of the Valsalva maneuver during the transthoracic saline contrast echocardiography.

Right-to-left shunt with hypoxemia in pulmonary hypertension

BACKGROUND

Hypoxemia is common in pulmonary hypertension (PH) and may be partly related to ventilation/perfusion mismatch, low diffusion capacity, low cardiac output, and/or right-to-left (RL) shunting.

METHODS

To determine whether true RL shunting causing hypoxemia is caused by intracardiac shunting, as classically considered, a retrospective single center study was conducted in consecutive patients with precapillary PH, with hypoxemia at rest (PaO2 < 10 kPa), shunt fraction (Qs/Qt) greater than 5%, elevated alveolar-arterial difference of PO2 (AaPO2), and with transthoracic contrast echocardiography performed within 3 months.

RESULTS

Among 263 patients with precapillary PH, 34 patients were included: pulmonary arterial hypertension, 21%; PH associated with lung disease, 47% (chronic obstructive pulmonary disease, 23%; interstitial lung disease, 9%; other, 15%); chronic thromboembolic PH, 26%; miscellaneous causes, 6%. Mean pulmonary artery pressure, cardiac index, and pulmonary vascular resistance were 45.8 +/- 10.8 mmHg, 2.2 +/- 0.6 L/min/m2, and 469 +/- 275 dyn.s.cm-5, respectively. PaO2 in room air was 6.8 +/- 1.3 kPa. Qs/Qt was 10.2 +/- 4.2%. AaPO2 under 100% oxygen was 32.5 +/- 12.4 kPa. Positive contrast was present at transthoracic contrast echocardiography in 6/34 (18%) of patients, including only 4/34 (12%) with intracardiac RL shunting. Qs/Qt did not correlate with hemodynamic parameters. Patients' characteristics did not differ according to the result of contrast echocardiography.

CONCLUSION

When present in patients with precapillary PH, RL shunting is usually not related to reopening of patent foramen ovale, whatever the etiology of PH.

Is transesophageal echocardiography still necessary to exclude patent foramen ovale?

OBJECTIVES

Current guidelines still recommend transesophageal echocardiography (TEE) as reference method to diagnose interatrial shunts. The aim was to test the accuracy of high-end transthoracal echocardiography (TTE) to exclude inter-atrial shunts.

METHODS

Prospective TTE and TEE study with second harmonic imaging to determine left-to-right shunt (L/R) by both colour Doppler or R/L by contrast echocardiography in patients with unexplained cerebrovascular incidents or newly detected valvular or myocardial disease.

RESULTS

An inter-atrial shunt was diagnosed in 200 of 438 analyzed patients (117 males). Colour Doppler echocardiography visualized a shunt in 67 patients (34%) on TTE vs. 84 (42%) patients on TEE (p <0.0001). However injection of agitated blood with a valsalva maneuver detected 190 (95%) interatrial shunts by both TTE and TEE, but 10 shunts (5%) only by TTE.

CONCLUSIONS

Our study shows that patent foramen ovale can safely be demonstrated with high-end transthoracic contrast- echocardiography. If additional studies confirm our results, TTE has the potential to become the method of choice in the diagnosis of PFO.

Comparison of transthoracic versus transesophageal echocardiography for detection of right-to-left atrial shunting using agitated saline contrast

Agitated saline contrast studies (bubble studies) can be performed with either transthoracic or transesophageal echocardiography for the detection of right-to-left atrial shunts. The echocardiograms of 94 consecutive patients who underwent saline contrast studies with transthoracic and transesophageal approaches were reviewed to compare the ability of these modalities to detect right-to-left atrial shunts.

Detection of cardiac right-to-left shunts by contrast-enhanced harmonic carotid duplex sonography

OBJECTIVE

Paradoxical embolization by cardiac right-to-left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast-enhanced transcranial Doppler sonography (ce-TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS.

METHODS

Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose-based nontranspulmonary contrast agent. The B-mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce-TCDS recordings of high-intensity transient signals from the MCA were analyzed offline.

RESULTS

In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high-intensity transient signals detected on ce-TCDS in the ipsilateral MCA.

CONCLUSIONS

The results of this study indicate that contrast-enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.

Evidence for increasing patency of the foramen ovale in divers

Using a standardized contrast-enhanced transesophageal echocardiographic technique, a group of divers was reexamined for the presence and size of patent foramen ovale (PFO) 7 years after their initial examinations. Unexpected but significant increases in the prevalence and size of PFO were found, suggesting a possible increasing risk for decompression sickness in these divers over time.

Patent foramen ovale and diving

Patency of the foramen ovale is a risk factor for DCS in SCUBA divers, even if they adhere to the currently accepted and used decompression tables. The primary cause of DCS, however, is the nitrogen bubble, not the PFO. There are a number of techniques any diver can use to minimize the occurrence of nitrogen bubbles after a dive. The authors current practice is to inform civilian sports divers of the increased risk and to advise them to adopt conservative dive profiles. This can be achieved by selecting a more conservative dive computer, performing only dives that do not require obligatory decompression stops, or using oxygen-enriched breathing gas mixtures("nitrox") while still diving on "air profiles" [56].Dive-safety organizations are currently under-taking studies aimed at proposing changes in the decompression algorithms to produce low-bubble dive tables [12]. In the meantime, PFO remains a reason for caution. Whether all divers should be screened for PFOis an ongoing discussion [50] in view of methodologic and practical issues outlined in this article. Any definitive recommendations can be made only after a careful, prospective evaluation of the real relative risk for DCS and long-term cerebral damage.

Recurrent transient ischemic attacks in a patient with intrapulmonary arteriovenous shunting detected after closure of a patent foramen ovale

Paradoxical embolism through right-to-left shunts is widely accepted as a potential cause of cerebral ischemia. Contrast echocardiography is an excellent tool for detection of these shunts. The timing of the appearance of bubbles in the left atrium (ie, early vs late) allows differentiation of foramen ovale patency from intrapulmonary shunting as a result of arteriovenous malformations. We report a patient with recurrent neurologic deficit after surgical closure of a patent foramen ovale. Transesophageal echocardiography demonstrated residual right-to-left shunting from previously unrecognized pulmonary arteriovenous malformations associated with hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu). This case illustrates the fact that contrast echocardiography may fail to identify intrapulmonary shunts when a resting patent foramen ovale coexists.

Harmonic Imaging Improves Sensitivity at the Expense of Specificity in the Detection of Patent Foramen Ovale

Contrast echocardiography using agitated saline is widely employed to detect right to left shunt in patients with suspected patent foramen ovale (PFO). The sensitivity of fundamental transthoracic echocardiography (FTTE) is often limited by poor far-field resolution. The purpose of this study was to evaluate the test characteristics of harmonic imaging during transthoracic echocardiography (HTTE) for the detection of PFO.

METHODS

Sixty-four patients referred for transesophageal echo (TEE) for clinical indications underwent FTTE and HTTE during saline contrast injections.

RESULTS

TEE identified nine PFOs. For FTTE, the sensitivity was 78% and the specificity was 100%. For HTTE, the sensitivity was 100% and the specificity was 82%. All ten false positives with HTTE occurred after five cardiac cycles, suggesting transpulmonary transit of the bubbles.

CONCLUSION

In the detection of PFO, HTTE improves sensitivity at the expense of specificity, particularly if the timing of contrast appearance in the left heart is ignored.

Assessment of the effects of various maneuvers on both atrial pressure changes

The aim of the present study was to determine which maneuver causes the greatest pressure difference between both atria by measuring right and left atrial pressures simultaneously after certain maneuvers. Thirty-two coronary care unit patients, whom a Swan-Ganz catheter was inserted because of acute left ventricular dysfunction, hypotension, sinus tachycardia with unknown cause, were included in this study. The basal values of peak right atrium (RA) pressure and corresponding pulmonary capillary wedge pressure (PCWP) were measured via two separated transducers. Patients were tutored with several trials to perform breath holding, successive three strong coughs, Valsalva maneuver, 20 degrees head down, respectively. In the end of these maneuvers, the peak RA pressure and corresponding PCWP were measured simultaneously. All maneuvers caused an increase in RA pressure. The highest peak RA pressure was obtained by means of the Valsalva maneuver (7.6 +/- 5 versus 20.4 +/- 7.6 mmHg before and after Valsalva, respectively; P<0.001). PCWP (18.8 +/- 5.9 mmHg) increased only with coughing (21.2 +/- 6.7 mmHg, P<0.01) and 20 degrees head down maneuver (20 +/- 5.7 mmHg, P<0.05). The highest increase in pressure gradient between peak RA pressure and corresponding PCWP was observed during Valsalva maneuver (-11 +/- 6.6 vs. 2.3 +/- 5.9 mmHg, P<0.001). The lowest increase was obtained in 20 degrees head down maneuver (-11 +/- 6.6 vs. -8.5 +/- 5.8 mmHg, P<0.001). When measuring the pressure of both atria invasively and simultaneously, Valsalva maneuver was the most effective maneuver consistent with pressure difference in favour of RA among all the other maneuvers.

Patent foramen ovale: a review of associated conditions and the impact of physiological size

Patent foramen ovale (PFO) is implicated in platypnea-orthodeoxia, stroke and decompression sickness (DCS) in divers and astronauts. However, PFO size in relation to clinical illness is largely unknown since few studies evaluate PFO, either functionally or anatomically. The autopsy incidence of PFO is approximately 27% and 6% for a large defect (0.6 cm to 1.0 cm). A PFO is often associated with atrial septal aneurysm and Chiari network, although these anatomic variations are uncommon. Methodologies for diagnosis and anatomic and functional sizing of a PFO include transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) and transcranial Doppler (TCD), with saline contrast. Saline injection via the right femoral vein appears to have a higher diagnostic yield for PFO than via the right antecubital vein. Saline contrast with TTE using native tissue harmonics or transmitral pulsed wave Doppler have quantitated PFO functional size, while TEE is presently the reference standard. The platypnea-orthodeoxia syndrome is associated with a large resting PFO shunt. Transthoracic echocardiography, TEE and TCD have been used in an attempt to quantitate PFO in patients with cryptogenic stroke. The larger PFOs (approximately > or =4 mm size) or those with significant resting shunts appear to be clinically significant. Approximately two-thirds of divers with unexplained DCS have a PFO that may be responsible and may be related to PFO size. Limited data are available on the incidence of PFO in high altitude aviators with DCS, but there appears to be a relationship. A large decompression stress is associated with extra vehicular activity (EVA) from spacecraft. After four cases of serious DCS in EVA simulations, a resting PFO was detected by contrast TTE in three cases. Patent foramen ovales vary in both anatomical and functional size, and the clinical impact of a particular PFO in various situations (platypnea-orthodeoxia, thromboembolism, DCS in underwater divers, DCS in high-altitude aviators and astronauts) may be different.