Transesophageal echocardiography: normal variants and mimickers

Fact or Artifact in Two-Dimensional Echocardiography: Avoiding Misdiagnosis and Missed Diagnosis

Two-dimensional transthoracic echocardiography is the most widely used noninvasive imaging modality for the evaluation and diagnosis of cardiac pathology. However, because of the physical properties of ultrasound waves and specifics in ultrasound image reconstruction, cardiologists are often confronted with ultrasound image artifacts. It is particularly important to recognize such artifacts in order to avoid misdiagnosis of conditions ranging from aortic dissection to thrombosis and endocarditis. This overview article summarizes the most common image artifacts encountered in routine clinical practice, along with explanations of their physical mechanisms and guidance in avoiding their misinterpretation.

Feasibility of TEE-guided stroke risk assessment in atrial fibrillation-background, aims, design and baseline data of the TIARA pilot study

Background

Antithrombotic management in atrial fibrillation (AF) is currently based on clinical characteristics, despite evidence of potential fine-tuning with transoesophageal echocardiography (TEE). This open, randomised, multicentre study addresses the hypothesis that a comprehensive strategy of TEE-based aspirin treatment in AF patients is feasible and safe.

Methods

Between 2005 and 2009, ten large hospitals in the Netherlands enrolled AF patients with a moderate risk of stroke. Patients without thrombogenic TEE characteristics were randomised to aspirin or vitamin K antagonists (VKA). The primary objective is to show that TEE-based aspirin treatment is safe compared with VKA therapy. The secondary objective tests feasibility of TEE as a tool to detect echocardiographic features of high stroke risk. This report compares randomised to non-randomised patients and describes the feasibility of a TEE-based approach.

Results

In total, 310 patients were included. Sixty-nine patients were not randomised because of non-visualisation (n = 6) or TEE risk factors (n = 63). Compared with non-randomised patients, randomised patients (n = 241) were younger (65 ± 11 vs. 69 ± 9 years, p = 0.004), had less coronary artery disease (9 vs. 20%, p = 0.018), previous TIA (1.7 vs. 7.2%, p = 0.029), AF during TEE (25 vs. 54%, p < 0.001), mitral incompetence (55 vs. 70%, p = 0.038), VKA use (69 vs. 82%, p = 0.032), had a lower mean CHADS₂ score (1.2 ± 0.6 vs. 1.6 ± 1.0, p = 0.004), and left ventricular ejection fraction (59 ± 8 vs. 56 ± 8%, p = 0.016).

Conclusions

This study shows that a TEE-based approach for fine-tuning stroke risk in AF patients with a moderate risk for stroke is feasible. Follow-up data will address the safety of this TEE-based approach.

Normal anatomic variants on transthoracic echocardiogram

Apart from their existence as medical curiosities, anatomic variants also double as diagnostic dilemmas. In the heart, more than in any other location in the body, misinterpretation of normal anatomic variants as pathologic entities can have a profound impact on treatment decisions and clinical consequences. Echocardiography is an easily accessible tool these days and is used routinely in most cardiac evaluations. Thus it becomes imperative for the echocardiographer to be cognizant of normal anatomic variants. Furthermore, echocardiographic findings should always be evaluated in their proper clinical context and diagnoses should never be entertained in a clinical vacuum. The literature is replete with numerous case reports and vignettes on these fascinating structures but is lacking in a formal review of normal anatomic variants. In this article, we have attempted a systemic review of normal variants, their embryologic origins, echocardiographic characteristics, and common pitfalls encountered in their evaluation.

Cardiovascular death in patients with atrial fibrillation is better predicted by left atrial thrombus and spontaneous echocardiographic contrast as compared with clinical parameters

We hypothesized that altered intra-atrial thrombogenicity, as reflected by the presence of left atrial (LA) thrombus or spontaneous echocardiographic contrast (SEC), would predict cardiovascular death in patients with atrial fibrillation (AF). In 175 patients with AF and no more than mild mitral regurgitation as detected by transesophageal echocardiography (TEE), 13 cardiovascular deaths occurred during a mean follow-up of 31 +/- 20 months. Multivariate logistic regression analysis using clinical variables identified the presence of congestive heart failure (relative risk [RR] = 4.22; P = .02) as the only positive predictor of cardiovascular death. However, when the TEE variables were added to the model, LA thrombus (RR = 5.52; P = .024) and LA SEC (RR = 7.96; P = .013) emerged as the only positive predictors of cardiovascular death. Kaplan-Meier analysis demonstrated a lower event-free survival from cardiovascular death in patients with LA thrombus and/or SEC ( P = .0013). These findings support AF as a contributing cause of cardiovascular death independent of clinically associated risk factors, such as hypertension, diabetes mellitus, smoking, congestive heart failure, and prior myocardial infarction.

Left atrial dissection: pathogenesis, clinical course, and transesophageal echocardiographic recognition

Left atrial dissection is an uncommon entity. It is generally associated with mitral valve replacement, but other predisposing factors should be considered in pathogenesis. We discuss a series of 11 patients with pathologically confirmed left atrial dissection who had been diagnosed previously by transesophageal echocardiography. Predisposing factors and surgical or pathologic findings were reviewed to identify the pathogenic mechanism and to explain the clinical course, hemodynamic disorder, and echocardiographic features. Dissection of the coronary sinus secondary to retrograde cardioplegia, endocarditis, cardiac rupture after myocardial infarction, and blunt chest trauma also could be related to its development. Transesophageal echocardiography identified a mobile intimal flap of the atrial wall that was creating a false chamber and allowed accurate diagnosis of prosthetic mitral valve function, endocarditis complications, and a left ventricular pseudoaneurysm after acute myocardial infarction. Color flow Doppler was particularly useful in identifying complications: communication between the false chamber and true left atria, permitting mitral regurgitation through the periannular route; development of atrial shunts; and severe tricuspid regurgitation caused by disruption of the anterior papillary muscle.

Elevated serum lipoprotein(a) is a risk factor for left atrial thrombus in patients with chronic atrial fibrillation: a transesophageal echocardiographic study

BACKGROUND

Patients with chronic atrial fibrillation have an increased risk of thromboembolism. Apoprotein(a) has a structural homology with plasminogen, suggesting that lipoprotein(a) [Lp(a)] may produce thrombogenic effects by modulating the fibrinolytic system. However, the role of Lp(a) level in the formation of left atrial thrombus has not been studied. We sought to evaluate whether Lp(a) is a risk factor for left atrial thrombus in patients with chronic atrial fibrillation.

METHODS AND RESULTS

The consecutive series of 150 patients (mean age 67 +/- 8 years) with chronic atrial fibrillation underwent transesophageal echocardiography. Left atrial thrombus was diagnosed by transesophageal echocardiography. Clinical, biochemical, and echocardiographic variables were prospectively collected. Univariate analysis showed that patients with left atrial thrombus (n = 29, 19%) had higher frequency of spontaneous echo contrast (93% vs 55%, P <.0001) than patients without left atrial thrombus (n = 121). Patients with left atrial thrombus also had a significantly higher serum concentration of Lp(a) (34.5 +/- 24.1 vs 17.9 +/- 13.5 mg/dL, P <.0001), a larger left atrium (5.4 +/- 0.9 vs 4.8 +/- 0.7 cm, P <.001), and a lower left atrial appendage peak flow velocity (11.1 +/- 5.4 vs 23.5 +/- 14.6 cm/s, P <.0001). Multivariate regression analysis showed that the Lp(a) concentration (P <.0001) was a significant positive predictor and the left atrial appendage peak flow velocity (P =.0125) was a significant negative predictor of left atrial thrombus. Left atrial thrombus was present in 16 (48%) of 33 patients with Lp(a) level >/=30 mg/dL.

CONCLUSIONS

Elevated serum levels of Lp(a) are strongly associated with left atrial thrombus. These findings suggest that Lp(a) level may be a novel risk factor for left atrial thrombus in patients with chronic atrial fibrillation.

A prospective, randomized, blinded comparison of multiplane and biplane transesophageal echocardiographic techniques

Although multiplane transesophageal echocardiography has become an accepted diagnostic technique, there is a paucity of literature directly comparing the diagnostic yield of multiplane and biplane transesophageal examinations. This study was designed to compare the ability of multiplane and biplane transesophageal echocardiographic techniques to visualize intracardiac structures. Complete multiplane and biplane transesophageal studies were performed on each of 50 patients (100 total studies) referred to the echocardiography laboratory for elective transesophageal echocardiography. The biplane examinations were performed with a multiplane probe with angles only at 0 and 90 degrees. Images of 29 prospectively selected cardiac structures and valvular function parameters were scored as follows: 0 = not visualized, 1 = visualized well enough to identify structure, 2 = diagnostic quality, and 3 = exceptional quality. The scores for the individual structures were combined to identify total structure visualization quality scores for each of the imaging techniques. A separate subjective score was also determined to assess the overall adequacy of each study for addressing the clinical indication. The total structure visualization quality score was significantly higher for multiplane transesophageal echocardiography than for biplane transesophageal echocardiography (49 +/- 7 versus 45 +/- 7; p = 0.0001). Several individual structures were visualized significantly better (p < 0.05) by the multiplane technique, including the left upper pulmonary vein, fossa ovalis, left main coronary artery, and proximal ascending aorta. The subjective score of overall adequacy of the study for addressing the clinical indication showed a strong trend (p < 0.06) in favor of the multiplane technique, with higher scores in 11 of 50 multiplane studies versus three of 50 biplane studies when the two techniques were compared in individual patients. Therefore multiplane transesophageal echocardiography provides superior overall visualization of intracardiac structures compared with biplane studies, particularly for the left upper pulmonary vein, fossa ovalis, left main coronary artery, and ascending aorta.

Transesophageal echocardiographic guidance of cardioversion in patients with atrial fibrillation

The role of TEE in the guidance of cardioversion of atrial fibrillation was studied. Thirty-seven (18%) of 206 patients had left atrial thrombus. Cardioversion was attempted in 153 patients receiving no (n = 107) or < 7 days (n = 46) of anticoagulation prophylaxis, in 27 patients after > or = 3 weeks of anticoagulation, and was cancelled in 26 patients, primarily on the basis of TEE findings. Left atrial thrombus was observed in 37 (18%) of 206 patients. No embolic complications occurred over a 4-week follow-up period. In 7 (41%) of 17 patients new left atrial appendage spontaneous echocardiographic contrast developed immediately after electric cardioversion. In this group, significant decreases occurred in the left atrial appendage maximal emptying shear rate (11.1 +/- 11.1 sec-1 vs 5.0 +/- 5.1 sec-1; p < 0.05), maximal filling shear rate (6.7 +/- 5.9 sec-1 vs 3.7 +/- 3.5 sec-1; p < 0.05), and peak emptying velocity (0.38 +/- 0.29 cm/sec vs 0.19 +/- 0.14 cm/sec; p < 0.05). In one patient a left atrial appendage thrombus formed after electric cardioversion. Left atrial thrombus resolved in 1 (5%) of 21 patients and became immobile in 0 (0%) of 16 patients after 3 to 5 weeks of anticoagulation but resolved (n = 9) or became immobile (n = 6) in 15 (71%) of 21 patients after > 5 weeks of anticoagulation. TEE-guided cardioversion was safely done without or with < 7 days of anticoagulation prophylaxis in selected patients, but the potential for left atrial thrombus to form after electric cardioversion makes anticoagulation advisable in all patients. The conventional recommendation of 3 to 4 weeks of anticoagulation prophylaxis before cardioversion is usually inadequate for left atrial thrombus to resolve or to become immobile.

Echocardiography in the evaluation of thoracic trauma

Echocardiography has become a useful diagnostic modality in the evaluation of cardiovascular injury after thoracic trauma. Valuable information about cardiac wall motion, valvular function, pericardial effusions, and ventricular volume status can be obtained without significant risk. More recent application for the diagnosis of traumatic aortic disruption provides a safer, easier, less expensive, and more accurate method for detecting these injuries. Cardiac evaluation with TTE is unsuccessful in approximately 20% of examinations and is unable to provide the image resolution of the more invasive transesophageal approach.

Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event: a transesophageal echocardiographic study

OBJECTIVES

The objective of this study was to determine the frequency of left atrial thrombus in patients with acute atrial fibrillation.

BACKGROUND

It is commonly assumed but unproved that left atrial thrombus in patients with atrial fibrillation begins to form after the onset of atrial fibrillation and that it requires > or = 3 days to form. Thus, patients with acute atrial fibrillation (i.e., < 3 days) frequently undergo cardioversion without anticoagulation prophylaxis.

METHODS

Three hundred seventeen patients (250 men, 67 women; mean [+/- SD] age 64 +/- 12 years) with acute (n = 143) or chronic (n = 174) atrial fibrillation were studied by two-dimensional transesophageal echocardiography.

RESULTS

Left atrial appendage thrombus was present in 20 patients (14%) with acute and 47 patients (27%, p < 0.01) with chronic atrial fibrillation. In patients with a recent embolic event, the frequency of left atrial appendage thrombus did not differ between those with acute (5 [21%] of 24) and those with chronic (12 [23%] of 52, p = NS) atrial fibrillation. Patients with acute versus chronic atrial fibrillation, respectively, did not differ (p = NS) in mean age (64 +/- 13 vs. 65 +/- 11 years), frequency of concentric left ventricular hypertrophy (32% vs. 26%), hypertension (32% vs. 41%), coronary artery disease (35% vs. 39%), congestive heart failure (43% vs. 48%), mitral stenosis (4% vs. 7%) or mitral valve replacement (1.4% vs. 6%). The minimally detectable difference in proportions between patients with acute and chronic atrial fibrillation based on a power of 0.80 and base proportion of 0.20 was 14%.

CONCLUSIONS

Left atrial thrombus does occur in patients with acute atrial fibrillation < 3 days in duration. The frequency of left atrial thrombus in patients with recent emboli is comparable between those with acute and chronic atrial fibrillation. These data suggest that patients with acute atrial fibrillation for < 3 days require anticoagulation prophylaxis or evaluation by transesophageal echocardiography before cardioversion and should not be assumed to be free of left atrial thrombus.

Diagnostic accuracy and therapeutic impact of transthoracic and transesophageal echocardiography in mechanically ventilated patients in the ICU

STUDY OBJECTIVES

To assess the respective diagnostic accuracy of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) and their therapeutic implications in mechanically ventilated patients, in the intensive care unit (ICU).

DESIGN

A prospective study.

SETTINGS

Intensive care units of two tertiary referral teaching hospitals.

PATIENTS

One hundred eleven ICU patients (81 men and 30 women; mean age 57 +/- 16 years). Fifty-seven percent were hospitalized for medical illnesses, 16.5 percent after thoracic surgery, 10.5 percent after other surgery, and 16.0 percent for multiple trauma. Their Simplified Acute Physiologic Score was 16 +/- 5.

INTERVENTIONS

The echocardiograms were performed in order to solve well-defined clinical problems. TTE was the first step of the procedure and TEE was performed only when (1) TTE did not solve the clinical problems, and (2) TTE yielded unsuspected findings requiring TEE. During each echocardiographic study, the following were noted: ventilatory mode, clinical problems, imaging quality, results, consequence on acute care, duration of the procedure, and potential complications of TEE. Diagnostic accuracy was defined as the proportion of solved problems, and therapeutic impact was defined as changes on acute care that resulted directly from the procedure.

MEASUREMENTS AND RESULTS

One hundred twenty-eight consecutive TTE and 96 TEE were performed. TTE solved 60 of 158 clinical problems (38 percent), whether positive end-expiratory pressure (> 4 cm H2O) was present or not (28 of 74 vs 32 of 84: p > 0.50). TTE allowed evaluation of left ventricular function in 77 percent of cases and pericardial effusion in every case, but it did not solve most of the other clinical problems. Indeed, the diagnostic accuracy of TEE was markedly superior (95/98 vs 60/158: p < 0.001), but TEE required a physician's presence longer (43 +/- 17 min vs 27 +/- 12 min: p < 0.001). When TTE and TEE were scheduled (n = 96), TEE yielded an additional diagnosis or excluded with more certitude a suspected diagnosis, except in two cases. TEE had a therapeutic impact more frequently than TTE (35/96 vs 20/128: p < 0.001). Cardiovascular surgery was prompted by echocardiographic findings in ten patients. TEE was well tolerated in all patients; there were no complications.

CONCLUSIONS

TEE is a valuable well-tolerated imaging technique in mechanically ventilated patients. For the assessment of left ventricular systolic function and pericardial effusion; however, TTE continues to be an excellent diagnostic tool, even when positive end-expiratory pressure is present. Both TTE and TEE have a therapeutic impact in approximately 25 percent of cases.