Transesophageal ultrasound offers imaging through the esophagus on the surface of the heart, with good image quality and unique advantages. However, no studies to date have examined its effect in critically ill patients in China.Therefore, the investigators aimed to compare the efficacy and safety of TEE with TTE. the investigators will conducte a Multi-center, prospective observational control study enrolling critically ill adult patients in several ICU in China .

Patients in ICU were assessed for the need for TEE by trained researcher. Eligible patients would be conducted tee examination by researcher A, TTE by the researcher B ,at the same time, researcher C records the basic condition and clinical data of patientsand carried out micro-enlargement test.The examination results are judged by A and B respectively and provided to the physician of this patient, and A return visit to the physician wold be conducted by researcher D to evaluate the acceptance of TTE and TEE results and judge the clinical effects. The primary outcome is the clinical effects.

Inclusion Criteria:

1. The quality of Transthoracic echocardiography is poor ( >3 sections cannot be obtained or the inner membrane is not clear)
2. The diagnosis of the etiology by Transthoracic ultrasonography is still unclear
3. The results of Transthoracic ultrasonography are inconsistent with clinical judgment or cannot explain the existing signs.
4. No obvious improvement or even aggravation after thoracic examination and corresponding treatment
5. Special conditions or clinical scenarios
6. Other clinicians think a TEE check is required.

Exclusion Criteria:

1. There is a tee test taboo and clinicians evaluate the risk over benefit
2. Did not sign an informed consent form