Transesophageal echocardiography for perioperative management in thoracic surgery

PURPOSE OF REVIEW

Perioperative transesophageal echocardiography (TEE) is most often employed during cardiac surgery. This review will summarize some of the recent findings relevant to TEE utilization during thoracic surgical procedures.

RECENT FINDINGS

Hemodynamic monitoring is a key component of goal-directed fluid therapy, which is also becoming more common for management of thoracic surgical procedures. Although usually not required for the anesthetic management of common thoracic surgeries, TEE is frequently used during lung transplantation and pulmonary thromboendarterectomy. Few clinical studies support current practice patterns, and most recommendations are based on expert opinion.

SUMMARY

Currently, routine use of TEE in thoracic surgery is often limited to specific high-risk patients and/or procedures. As in other perioperative settings, TEE may be utilized to elucidate the reasons for acute hemodynamic instability without apparent cause. Contraindications to TEE apply and have to be taken into consideration before performing a TEE on a thoracic surgical patient.

Right Ventricular Systolic Assessment by Transesophageal Versus Transthoracic Echocardiography: Displacement, Velocity, and Myocardial Deformation

OBJECTIVE

First, to compare tricuspid annular displacement and velocity in transthoracic and transesophageal echocardiography (TTE, TEE) using conventional angle-dependent technologies. Second, to evaluate both alternative TEE views as well as an alternative technology (speckle tracking) for overcoming proposed differences in TTE and TEE.

DESIGN

Prospective, comparative, cross-over study with a randomized order of image acquisition.

SETTING

University hospital.

PARTICIPANTS

Adults undergoing cardiac surgery.

INTERVENTIONS

Postinduction standardized image acquisition and analysis in TTE and TEE by 2 echocardiographers.

MEASUREMENTS AND MAIN RESULTS

The authors measured tricuspid annular plane systolic excursion (TAPSE) by M-mode and velocity by tissue Doppler (S') in the apical 4-chamber TTE view and midesophageal 4-chamber TEE view (AP4C, ME4C). They then examined (1) the same measurements in alternative TEE views with proposed better ultrasound angulation; and (2) speckle tracking-based endpoints (TAPSE by speckle tracking, strain, and strain rate). Data were available in 24 of 25 patients. Conventional TAPSE by M-mode and velocity by tissue Doppler (TDI) were underestimated in the ME4C compared with the AP4C reference (mean ± standard deviation: TAPSE: 13.1 ± 3.8 mm v 17.3 ± 4.0 mm; S': 6.7 ± 2.1 cm/s v 9.1 ± 2.2 cm/s; both p < 0.001). Neither a modified deep transgastric view (TAPSE 14.5 ± 4.7 mm, p = 0.017; S' 6.8 ± 1.8 cm/s, p < 0.001) nor a transgastric right ventricular inflow view (TAPSE 12.3 ± 4.0 mm, p = 0.001; S' 6.0 ± 1.3 cm/s, p < 0.001) was similar to the AP4C. Speckle tracking TAPSE was unbiased but with high variability (mean bias = -0.3 mm, 95% limits of agreement = -9.1 to 8.4); strain and strain rate were higher in TEE than for TTE (-17.7 ± 3.6 v -12.6 ± 2.1, p < 0.001; -1.0 ± 0.2/s v -0.7 ± 0.1/s, p < 0.001).

CONCLUSIONS

Right ventricular displacement, velocity, and myocardial deformation measured by TEE versus TTE are different. Neither alternative transesophageal echocardiography views nor speckle tracking-based deformation is promising; TAPSE by speckle tracking is unbiased but imprecise.

Assessing Right Ventricular Function in the Perioperative Setting, Part II: What About Catheters?

An-depth assessment of right ventricular function is important in a many perioperative settings. After exploring 2-dimensional echo-based evaluation, other proposed monitoring modalities are discussed. Pressure-based methods of right ventricular appraisal is discussed. Flow-based assessment is reviewed. An overview of the state of current right ventricular 3-dimensional echocardiography and its potential to construct clinical pressure-volume loops in conjunction with pressure measurements is provided. An overview of right ventricular assessment modalities that do not rely on 2-dimensional echocardiography is discussed. Tailored selection of monitoring modalities can be of great benefit for the perioperative physician. Integrating modalities offers optimal estimations of right ventricular function.

Assessing Right Ventricular Function in the Perioperative Setting, Part I: Echo-Based Measurements

This article reviews transesophageal echocardiography-based assessment of perioperative right ventricular function and failure, including catheter-based methods, three-dimensional echocardiography, and their combination to make pressure-volume loops. It outlines right ventricular pathophysiology, multiple assessment methods, and their relationship to analogous transthoracic echocardiogram measurements. technologies used and developed for transthoracic or left ventricular assessment show significant limitations when applied to transesophageal assessment of the right ventricle. The article provides an overview of right ventricular assessment modalities that can be used in transesophageal echocardiography. Ultimately, clinicians must know limitations of measurements, synthesize information, and assess it in the clinical context.

Lung recruitment improves right ventricular performance after cardiopulmonary bypass: A randomised controlled trial

BACKGROUND

Atelectasis after cardiopulmonary bypass (CPB) can affect right ventricular (RV) performance by increasing its outflow impedance.

OBJECTIVE

The aim of this study was to determine whether a lung recruitment manoeuvre improves RV function by re-aerating the lung after CPB.

DESIGN

Randomised controlled study.

SETTING

Single-institution study, community hospital, Córdoba, Argentina.

PATIENTS

Forty anaesthetised patients with New York Heart Association class I or II, preoperative left ventricular ejection fraction at least 50% and Euroscore 6 or less scheduled for cardiac surgery with CPB.

INTERVENTIONS

Patients were assigned to receive either standard ventilation with 6 cmH2O of positive end-expiratory pressure (PEEP; group C, n = 20) or standard ventilation with a recruitment manoeuvre and 10 cmH2O of PEEP after surgery (group RM, n = 20). RV function, left ventricular cardiac index (CI) and lung aeration were assessed by transoesophageal echocardiography (TOE) before, at the end of surgery and 30 min after surgery.

MAIN OUTCOME MEASURES

RV function parameters and atelectasis assessed by TOE.

RESULTS

Haemodynamic data and atelectasis were similar between groups before surgery. At the end of surgery, CI had decreased from 2.9 ± 1.1 to 2.6 ± 0.9 l min m in group C (P = 0.24) and from 2.8 ± 1.0 to 2.6 ± 0.8 l min m in group RM (P = 0.32). TOE-derived RV function parameters confirmed a mild decrease in RV performance in 95% of patients, without significant differences between groups (multivariate Hotelling t-test P = 0.16). Atelectasis was present in 18 patients in group C and 19 patients in group RM (P = 0.88). After surgery, CI decreased further from 2.6 to 2.4 l min m in group C (P = 0.17) but increased from 2.6 to 3.7 l min m in group RM (P < 0.001). TOE-derived RV function parameters improved only in group RM (Hotelling t-test P < 0.001). Atelectasis was present in 100% of patients in group C but only in 10% of those in group RM (P < 0.001).

CONCLUSION

Atelectasis after CPB impairs RV function but this can be resolved by lung recruitment using 10 cmH2O of PEEP.

TRIAL REGISTRATION

Protocol started on October 2014.

Right Ventricular Longitudinal Strain In Left Ventricular Assist Device Surgery-A Retrospective Cohort Study

OBJECTIVES

Right ventricular (RV) failure is common after left ventricular assist device (LVAD) surgery and is associated with higher mortality. Measurement of longitudinal RV strain using speckle-tracking technology is a novel approach to quantify RV function. The authors hypothesized that depressed peak longitudinal RV strain measured by intraoperative transesophageal echocardiography (TEE) examinations would be associated with adverse outcomes after LVAD surgery.

DESIGN

Retrospective cohort study.

SETTING

Tertiary academic medical center.

PARTICIPANTS

Following Institutional Review Board approval, the authors retrospectively identified adult patients who underwent implantation of non-pulsatile LVAD. Exclusion criteria included inadequate TEE images and device explantation within 6 months for heart transplantation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The postoperative adverse event outcome was defined as a composite of one or more of death within 6 months, ≥14 days of inotropes, mechanical RV support, or device thrombosis. Intraoperative TEE images were analyzed for peak RV free wall longitudinal strain by two blinded investigators. Simple logistic regression was used to assess the relationship between adverse outcome and the mean of the strain measurements of the two raters. Agreement between the raters was assessed by intra-class correlation (0.62) and Pearson correlation coefficient (0.63). Of the 57 subjects, 21 (37%) had an adverse outcome. The logistic regression indicated no significant association between RV peak longitudinal strain and adverse events.

CONCLUSIONS

In this retrospective study of patients undergoing non-pulsatile LVAD implantation, peak longitudinal strain of the RV free wall was not associated with adverse outcomes within 6 months after surgery. Additional quantitative echocardiographic measures for intraoperative RV assessment should be explored.

Right Ventricular Longitudinal Strain Is Depressed in a Bovine Model of Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension and resulting right ventricular (RV) dysfunction are associated with significant perioperative morbidity and mortality. Although echocardiography permits real-time, noninvasive assessment of RV function, objective and comparative measures are underdeveloped, and appropriate animal models to study their utility are lacking. Longitudinal strain analysis is a novel echocardiographic method to quantify RV performance. Herein, we hypothesized that peak RV longitudinal strain would worsen in a bovine model of pulmonary hypertension compared with control animals.

METHODS

Newborn Holstein calves were randomly chosen for induction of pulmonary hypertension versus control conditions. Pulmonary hypertension was induced by exposing animals to 14 days of hypoxia (equivalent to 4570 m above sea level or 430 mm Hg barometric pressure). Control animals were kept at ambient pressure/normoxia. At the end of the intervention, transthoracic echocardiography was performed in awake calves. Longitudinal wall strain was analyzed from modified apical 4-chamber views focused on the RV. Comparisons between measurements in hypoxic versus nonhypoxic conditions were performed using Student t test for independent samples and unequal variances.

RESULTS

After 14 days at normoxic versus hypoxic conditions, 15 calves were examined with echocardiography. Pulmonary hypertension was confirmed by right heart catheterization and associated with reduced RV systolic function. Mean systolic strain measurements were compared in normoxia-exposed animals (n = 8) and hypoxia-exposed animals (n = 7). Peak global systolic longitudinal RV strain after hypoxia worsened compared to normoxia (-10.5% vs -16.1%, P = 0.0031). Peak RV free wall strain also worsened after hypoxia compared to normoxia (-9.6% vs -17.3%, P = 0.0031). Findings from strain analysis were confirmed by measurement of tricuspid annular peak systolic excursion.

CONCLUSIONS

Peak longitudinal RV strain detected worsened RV function in animals with hypoxia-induced pulmonary hypertension compared with control animals. This relationship was demonstrated in the transthoracic echocardiographic 4-chamber view independently for the RV free wall and for the combination of the free and septal walls. This innovative model of bovine pulmonary hypertension may prove useful to compare different monitoring technologies for the assessment of early events of RV dysfunction. Further studies linking novel RV imaging applications with mechanistic and therapeutic approaches are needed.

Intraoperative Monitoring of Pulmonary Artery Physiology With Transesophageal Echocardiography in a Patient With an Extensive Pulmonary Aneurysm Undergoing Partial Nephrectomy

Surgical patients with pulmonary hypertension present a significant challenge to the anesthesiologist. Continuous perioperative monitoring of pulmonary artery (PA) pressure is recommended and most often accomplished with a PA catheter. Placement of a PA catheter may be difficult or contraindicated, and in these cases, transesophageal echocardiography is a useful alternative to monitor dynamic PA physiology. In this case, we used intraoperative transesophageal echocardiography to detect changes in peak PA pressure and guide clinical treatment in a patient with pulmonary hypertension and an extensive PA aneurysm undergoing partial nephrectomy.