11.3.5 The role of intraoperative TEE

 Transoesophageal echocardiography (TEE) plays a key role in valve surgery as it has a very significant impact [1,7,8].

• It guides the anaesthetist and surgeon to the best technique to ensure haemodynamic balance and optimise the surgical procedure. In valve surgery, the rate of change in the treatment plan based on intraoperative TEE is 11-14%, compared with an average of 7% in all cardiac surgery [2,4,7,9]. In addition, in 6-8% of cases, TEE revealed a cardiac lesion that had not been suspected at preoperative assessment, justifying an additional unplanned correction [5,13].
• Prior to ECC, the functional anatomy of the heart can be assessed, i.e. how the structures have adapted to the valvular disease and the degree of decompensation of the myocardium (see Figure 11.14). In the case of polyvalvular disease, this examination makes it possible to assess the predominant lesions and helps to define the primary pathology and the secondary or functional lesions.
• After ECC, it allows immediate monitoring of the quality of valve reconstruction and prosthesis function, highlighting any residual defects. In 2-6% of cases, it justifies a return to bypass surgery to correct an anomaly (paravalvular leak, inadequate prosthesis) [2,4,5,7]; this repeat operation also avoids a subsequent reoperation with a higher mortality rate.
• For anaesthetists, TEE offers unrivalled monitoring of blood volume in situations where filling pressures are poor reference points due to diastolic dysfunction and valvular disease. It provides a highly accurate analysis of ventricular function despite caval remodelling and variations in stress and systolic performance during procedures. It can be used to diagnose haemodynamic effects such as dynamic stenosis of the LV outflow tract that cannot be detected by other methods.
• TEE is an integral part of certain procedures, as this imaging is required for the placement of certain cannulae or prostheses and for immediate visualisation of the surgical procedure (implantation of stentless or endovascular prostheses, minimally invasive surgery, percutaneous plasty, etc.).

Intraoperative TEE is a definite recommendation for valve surgery, for the insertion of an unmounted prosthesis or homograft, and in cases of endocarditis; it is desirable, but not essential, for the insertion of a mechanical prosthesis or a mounted bioprosthesis [10,15].

The examination must always be complete: morphology and function of both ventricles, valve anatomy, colour flow and spectral Doppler, calculation of gradients and orifice areas. Any discrepancies between the various elements must be explained. As flow measurements are dynamic, they are dependent on the patient's circulatory state, which is significantly altered by anaesthesia. For example, inadequacy decreases by 1 to 2 degrees on a scale of 4 simply as a result of general anaesthesia [6]. Any quantification of regurgitation must be made after normal haemodynamics have been restored, if necessary with an arterial vasopressor. If the patient is arrhythmic, measurements should be taken over cardiac cycles with a diastolic duration corresponding to a frequency of approximately 70 beats/minute, repeated and averaged over 3-5 measurements.

After valve replacement, TEE is essential to assess the reconstruction: tightness, residual prolapse, restriction to anterograde flow, dynamic obstruction of the LVOT, etc. Residual leak must be tested under severe haemodynamic conditions (MAP 90-100 mmHg). Residual leak must be tested under severe haemodynamic conditions (MAP 90-100 mmHg). Immediate monitoring after mitral valve surgery has excellent predictive value in the medium term, as there is no significant change in the degree of regurgitation between that found at the end of ECC and that diagnosed six months after surgery [3,12]. After prosthetic valve implantation, TEE should answer several questions:

• Is the amount of leakage normal?
• Is there a paravalvular leak?
• Is the orifice free and does the occlusion show normal coaptation?
• Are the flows and gradients within the norms for the type of prosthesis?
• What is the effect of replacing one valve on the function of the others? Is it necessary to work on other valves?
• Is there a dynamic obstruction in the atrial chamber?
• Is the ventricular function adequate?
• Have there been changes in segmental kinetics?

• The right and left upper pulmonary veins;
• The upper part of the left interatrial septum;
• The mitral valve angle;
• The apical septum of the left ventricle (in Trendelenburg position);
• The right aortic sinus of Valsalva;
• To assess the extent of systemic emboli, bubbles can be observed in the descending aorta and the TEE probe can be rotated backwards.

• Continuous suction maintained by the cardioplegia cannula in place at the root of the ascending aorta;
• Shaking and manipulation of the heart;
• Rolling the operating table;
• Trendelenburg position;
• Hyperinflation and lung compression;
• Inotropic stimulation;
• Atrial drainage by direct needle puncture and aspiration;
• Ventricular drainage by apical or transseptal puncture.

 

© CHASSOT PG, BETTEX D, August 2011, last update November 2019