The Feasibility of Measuring Renal Blood Flow Using Transesophageal Echocardiography in Patients Undergoing Cardiac Surgery

Transgastric Abdominal Ultrasonography in Anesthesia and Critical Care: Review and Proposed Approach

The use of transesophageal echocardiography (TEE) in the operating room and intensive care unit can provide invaluable information on cardiac as well as abdominal organ structures and function. This approach may be particularly useful when the transabdominal ultrasound examination is not possible during intraoperative procedures or for anatomical reasons. This review explores the role of transgastric abdominal ultrasonography (TGAUS) in perioperative medicine. We describe several reported applications using 10 views that can be used in the diagnosis of relevant abdominal conditions associated with organ dysfunction and hemodynamic instability in the operating room and the intensive care unit.

Feasibility of measuring superior mesenteric artery blood flow during cardiac surgery under hypothermic cardiopulmonary bypass using transesophageal echocardiography: An observational study

Background:

Abdominal complications being rare but results in high mortality, commonly due to splanchnic organ hypoperfusion during the perioperative period of cardiac surgery. There are no feasible methods to monitor intraoperative superior mesenteric artery blood flow (SMABF). Hence, the aim of this study was to evaluate the feasibility and to measure SMABF using transesophageal echocardiography (TEE) during cardiac surgery under hypothermic cardiopulmonary bypass (CPB).

Methodology:

Thirty-five patients undergoing elective cardiac surgery under CPB were enrolled. Heart rate, mean arterial pressure (MAP), cardiac output (CO), SMABF, superior mesenteric artery (SMA) diameter, superior mesentric artery blood flow over cardiac output (SMA/CO) ratio and arterial blood lactates were recorded at three time intervals. T0: before sternotomy, T1: 30 min after initiation of CPB and T2: after sternal closure.

Results:

SMA was demonstrated in 32 patients. SMABF, SMA diameter, SMA/CO, MAP and CO decreased significantly (P < 0.0001) between T0 and T1, increased significantly (P ≤ 0.001) between T0 and T2. Lactates increased progressively from T0 to T2.

Conclusion:

Study shows that there is decrease in SMABF during CPB and returns to baseline after CPB. Hence, it is feasible to measure SMABF using TEE in patients undergoing cardiac surgery under hypothermic CPB. TEE can be a promising tool in detecting and preventing splanchnic hypoperfusion during perioperative period.

Doppler-based renal resistance index for the detection of acute kidney injury and the non-invasive evaluation of paravalvular aortic regurgitation after transcatheter aortic valve implantation

AIMS

Acute kidney injury (AKI) is a strong but rather late predictor of mortality after transcatheter aortic valve implantation (TAVI). Early clinically useful markers for the detection of AKI and prediction of outcome are needed in order to control and improve management of periprocedural complications after TAVI. The aim of our study was to assess the predictive value of the Doppler-based renal resistance index (RRI), which correlates inversely with effective renal blood flow and creatinine clearance, for AKI in patients undergoing TAVI and to evaluate its association with paravalvular aortic regurgitation (PAR).

METHODS AND RESULTS

TAVI was performed with the Medtronic CoreValve prosthesis in 132 consecutive high-risk patients (mean logistic EuroSCORE: 30.3±18.2%). RRI, serum creatinine and cystatin C level were determined before, and 4 hrs, 24 hrs, 48 hrs, 72 hrs, and 7 days after TAVI. AKI occurred in 32/132 patients (24.2%). While serum creatinine and cystatin C levels decreased at first after TAVI (also in most patients developing AKI), the RRI increased significantly immediately after the procedure from 0.79±0.09 to 0.87±0.12 in patients developing AKI (p=0.003). A RRI >0.85 predicted post-interventional AKI with a sensitivity of 58% and specificity of 86%, and was superior to the serum creatinine level (p<0.001). In addition, an elevated RRI was significantly related to haemodynamic changes after TAVI and was associated with the occurrence of moderate/severe PAR (p<0.001).

CONCLUSIONS

Measurement of the Doppler-based RRI predicts risk for AKI and increased mortality rates at an early post-procedural time point and is related to the occurrence of more-than-mild paravalvular aortic regurgitation after TAVI.

Unexpected co-arctation of aorta detected by transesophageal echocardiography during patent ductus arteriosus ligation

In the presence of a large patent ductus arteriosus (PDA), aortic co-arctation (CoA) cannot be diagnosed clinically because PDA masks the clinical features. This condition impedes the identification of CoA by transthoracic echcocardiography. However, the closure of PDA can result in a severe clinical condition that causes a patient with undiagnosed CoA to suffer from shock and multi-organ failure. In this article, a case of PDA was presented, in which transesophageal echocardiography provided full information that could be used as reference to identify and define CoA during PDA ligation surgery.