Perioperative Echokardiographie

[Application fields of intraoperative transesophageal 3D echocardiography]

Intraoperative transesophageal echocardiography (TEE) is an established diagnostic tool and has to be regarded as the standard of care for intraoperative monitoring and cardiac surgical decision-making. Furthermore, intraoperative TEE is also used for monitoring and assessment of hemodynamic changes and the detection of previously unknown pathologies. In the past few years 3D-TEE has extended the spectrum of 2D-TEE by allowing pathomorphological features to be more easily and intuitively linked to the anatomy of the heart and the great vessels. Thus, a comprehensive 2D-TEE examination is favorably complemented by focused 3D-TEE. Especially during mitral valve surgery, 3D-TEE has proven its superiority in the diagnosis of the underlying pathology as demonstrated by a large number of studies in this field. This review presents the available data about the role of intraoperative 3D-TEE echocardiography and introduces practical fields of application.

Evaluation of transmitral pressure gradients in the intraoperative echocardiographic diagnosis of mitral stenosis after mitral valve repair

Objective

Acute mitral stenosis (MS) following mitral valve (MV) repair is a rare but severe complication. We hypothesize that intraoperative echocardiography can be utilized to diagnose iatrogenic MS immediately after MV repair.

Methods

The medical records of 552 consecutive patients undergoing MV repair at a single institution were reviewed. Post-cardiopulmonary bypass peak and mean transmitral pressure gradients (TMPG), and pressure half time (PHT) were obtained from intraoperative transesophageal echocardiographic (TEE) examinations in each patient.

Results

Nine patients (9/552 = 1.6%) received a reoperation for primary MS, prior to hospital discharge. Interestingly, all of these patients already showed intraoperative post-CPB mean and peak TMPGs that were significantly higher compared to values for those who did not: 10.7±4.8 mmHg vs 2.9±1.6 mmHg; p<0.0001 and 22.9±7.9 mmHg vs 7.6±3.7 mmHg; p<0.0001, respectively. However, PHT varied considerably (87±37 ms; range: 20–439 ms) within the entire population, and only weakly predicted the requirement for reoperation (113±56 vs. 87±37 ms, p = 0.034). Receiver operating characteristic curves showed strong discriminating ability for mean gradients (AUC = 0.993) and peak gradients (area under the curve, AUC = 0.996), but poor performance for PHT (AUC = 0.640). A value of ≥7 mmHg for mean, and ≥17 mmHg for peak TMPG, best separated patients who required reoperation for MS from those who did not.

Conclusions

Intraoperative TEE diagnosis of a peak TMPG ≥17 mmHg or mean TMPG ≥7 mmHg immediately following CPB are suggestive of clinically relevant MS after MV repair.

[How should anesthesiologists perform ultrasound examinations? Diagnostic use of ultrasound in emergency and intensive care and medicine]

Ultrasound imaging has attained great significance as a tool for diagnostics in emergency and intensive care medicine. The major advantages of this technique are its instantaneous bedside availability and the possibility to perform repeatable examinations. These advantages are based on recent developments, such as portable ultrasound devices offering excellent imaging quality as well as a quick-start-function. Ultrasound imaging in critically ill patients is frequently performed under pressure of time depending on the current acute physical state. All standard examinations in echocardiography, vascular, abdominal and thoracic ultrasound scanning can be applied in these patients. Based on the clinical scenario the duration of examinations may vary from seconds during cardiopulmonary resuscitations to time-consuming repeated scanning. The transition from basic to subject-specific detailed examinations is flowing and has to be adjusted to local conditions. In the field of emergency and intensive care medicine the technique used is whole-body sonography. The goal is to classify the patient's present physical state and to define a targeted therapeutic approach. The characteristics of whole-body sonography are similar to the field of anesthesiology which is an interdisciplinary one. Currently, these characteristics deserve more attention in training in sonography.

Importance of transesophageal echocardiography in the critically ill and injured patient

Echocardiography, particularly transesophageal echocardiography (TEE), is a vital diagnostic and monitoring imaging modality for the intensivist. The field of echocardiography spans different venues and pathologies, ranging from surface transthoracic echocardiography and portable hand-held echocardiography, to contrast echocardiography, stress echocardiography, and TEE, among others. Numerous investigations have proven the worth of echocardiography, especially TEE, in the critically ill and injured patient, changing lives with the identification of obvious and subtle cardiothoracic diseases. Because this powerful imaging tool is immediately available and portable, crucial delays in diagnosis are not commonplace; rather than echocardiography, TEE, specifically, should be (and is in some institutions) the standard of care and management in assisting the intensivist in diagnosis of a variety of maladies. The effect of TEE technology is quite formidable, and numerous investigations have borne this out. The therapeutic effect of TEE ranges from 10% to 69%, with the majority of investigations falling into the 60% to 65% range. The diagnostic yield of TEE is far greater, approaching 78%. This article will detail the importance of echocardiography, its efficacy, and its high-yield imaging capability, particularly when compared with other imaging modalities, even transthoracic echocardiography.

[Echocardiography during acute hemodynamic instability]

In light of the growing proportion of illness in the general population, the complexity of modern surgery requires precise perioperative hemodynamic monitoring. Echocardiography has emerged over the past 15 years as an especially valuable diagnostic instrument for intensive medicine. No other monitoring technique provides in such a short time, with so little invasiveness, so much additional anatomic information for determining the cause of acute hemodynamic instability. There is of course the possibility of proceeding transthoracally at first, with poor imaging quality but noninvasively, or transesophageally. However, perioperative hemodynamic monitoring allows even less experienced operators to detect the various differential diagnoses of acute hemodynamic instability with an easily managed number of standard images. Starting from the first standard settings, depending on pathology the imaging should continue selectively with transthoracal echocardiography in the short parasternal axis or transesophageal echocardiography in the transgastral short midpapillary axis.