Transesophageal two-dimensional echocardiography: current perspectives

Comparison of transesophageal and transthoracic contrast echocardiography for detection of an intrapulmonary shunt in liver disease

STUDY OBJECTIVES

Contrast transthoracic echocardiography (TTE) is currently used to identify intrapulmonary shunt (IPS) in patients with end-stage liver disease. The aim of this study was to compare the use of contrast TTE and transesophageal echocardiography (TEE) in detecting IPS.

DESIGN

Thirty-seven consecutive outpatients with severe liver disease awaiting liver transplantation underwent contrast TEE and TTE. The IPS was assessed semiquantitatively in four grades with TEE and as positive or negative with TTE.

SETTING

ICU.

INTERVENTIONS

Patients underwent contrast TEE after pharyngeal anesthesia alone followed by contrast TTE. Contrast echocardiography was performed with a modified fluid gelatin solution.

RESULTS

Overall detection rate of an IPS was 51% with TEE and 32% with TTE (p < 0.001). Four patients had an IPS detected with TEE but not with TTE. Quality of imaging was poor in 22% with TTE and 0% with TEE (p < 0.001). A PaO2 < 80 mm Hg or a dyspnea was associated with an IPS in 56% and 50% of patients with TEE and in 33% and 25% with TTE, respectively.

CONCLUSION

Contrast-enhanced TEE is superior to TTE for detecting an IPS in patients with severe liver disease awaiting liver transplantation. The use of gelatin contrast solution allows an early detection of IPS. Because of the high sensitivity of TEE, all patients suspected of hepatopulmonary syndrome should undergo TEE in search of an IPS if TTE is normal.

Spontaneous echo contrast and thromboembolism

Spontaneous echocardiographic contrast (a swirling, smokelike haze that appears in blood during imaging) indicates a predisposition to thromboembolism, particularly in patients with atrial fibrillation and elevation of hematocrit, ESR, and serum fibrinogen.

Transesophageal echocardiography

Preview Echocardiography is invaluable in assessing patients with known or suspected cardiac disorders. However, there are often impediments to adequate imaging using the standard transthoracic route (eg, mechanical ventilation, bandages). Transesophageal imaging overcomes many of these technical limitations and, as one researcher notes, provides a "new window to the heart." Drs Peterson and Orsinelli review common clinical applications of the procedure and adjunctive uses.

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.

Setting up a transoesophageal echocardiography service

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