The cardiac anesthesiologist must constantly be on the look-out for adverse changes in physiology, and must be particularly vigilant during the transition on and off cardiopulmonary bypass. Even during bypass potential complications may arise that require acute intervention.
Transesophageal echocardiography is particularly useful during bypass to watch for ventricular distension. Dr. Michael A. Fierro, Loyola University Medical Center, Maywood, Illinois, and coauthors describe how transesophageal echocardiography was used to help explain the reason for left ventricular distension at the end of cardiopulmonary bypass for an 80-year-old patient undergoing aortic valve replacement and cardiac artery bypass graft in the article titled “Intraoperative Transesophageal Echocardiography to Evaluate Acute Cessation of Venous Inflow During Cardiopulmonary Bypass,” which is featured in the current edition of A&A Case Reports.
In this case the aortotomy was closed after the aortic valve was placed. The surgeon then turned to the anastomosis of the posterior descending artery to the saphenous vein graft. Concurrently, the right atrium and ventricle became distended, and flow from the venous cannula to the cardiopulmonary bypass circuit decreased. Repositioning of the cannula did not relieve the obstructed flow.
TEE revealed an echogenic mass occluding the venous cannula. The appearance suggested clot. The right atrium was opened and the clot was removed. Because of concern about additional clotting, bypass of the left main coronary artery as aborted. The remainder of the case was uneventful.
The most likely source of clot was from a distal vein. Indeed, a soleal vein thrombus in the mid-calf was subsequently identified postoperatively.
This case demonstrates the value of TEE to help make clinical decisions during cardiopulmonary bypass, even though there is no net cardiac blood flow.
Dr. Martin London, Department of Anesthesia and Perioperative Care, UCSF VA Medical Center, San Francisco, California, notes in his accompanying editorial, “In many practices the TEE image is ‘frozen’ as soon as CPB commences.” In the editorial comment he describes how the TEE can be used to assess that cardiopulmonary bypass is proceeding unremarkably. “Detection of thromboembolism by capture into the venous cannula appears to be quite a unique way to make this diagnosis as these authors so well describe.”