Imaging the dynamics and microstructure of fibrin clot polymerization in cardiac surgical patients using spectrally encoded confocal microscopy.

During cardiac surgery with cardiopulmonary bypass (CPB), altered hemostatic balance may disrupt fibrin assembly, predisposing patients to perioperative hemorrhage. We investigated the utility of a novel device termed spectrally-encoded confocal microscopy (SECM) for assessing fibrin clot polymerization following heparin and protamine administration in CPB patients. SECM is a novel, high-speed optical approach to visualize and quantify fibrin clot formation in three dimensions with high spatial resolution (1.0 µm) over a volumetric field-of-view (165 × 4000 × 36 µm). The measurement sensitivity of SECM was first determined using plasma samples from normal subjects spiked with heparin and protamine. Next, SECM was performed in plasma samples from patients on CPB to quantify the extent to which fibrin clot dynamics and microstructure were altered by CPB exposure. In spiked samples, prolonged fibrin time (4.4 ± 1.8 to 49.3 ± 16.8 min, p < 0.001) and diminished fibrin network density (0.079 ± 0.010 to 0.001 ± 0.002 A.U, p < 0.001) with increasing heparin concentration were reported by SECM. Furthermore, fibrin network density was not restored to baseline levels in protamine-treated samples. In CPB patients, SECM reported lower fibrin network density in protaminized samples (0.055 ± 0.01 A.U. [Arbitrary units]) vs baseline values (0.066 ± 0.009 A.U.) (p = 0.03) despite comparable fibrin time (baseline = 6.0 ± 1.3, protamine = 6.4 ± 1.6 min, p = 0.5). In these patients, additional metrics including fibrin heterogeneity, length and straightness were quantified. Note, SECM revealed that following protamine administration with CPB exposure, fibrin clots were more heterogeneous (baseline = 0.11 ± 0.02 A.U, protamine = 0.08 ± 0.01 A.U, p = 0.008) with straighter fibers (baseline = 0.918 ± 0.003A.U, protamine = 0.928 ± 0.0006A.U. p < 0.001). By providing the capability to rapidly visualize and quantify fibrin clot microstructure, SECM could furnish a new approach for assessing clot stability and hemostasis in cardiac surgical patients.

Agreement Between Transesophageal Echocardiographic Tricuspid Annular Plane Systolic Excursion Measurement Methods in Cardiac Surgery Patients.

OBJECTIVE: To assess the agreement between 2-dimensional tricuspid annular plane systolic excursion (2D-TAPSE), 2D-TAPSE-apex, and 2D speckle tracking echocardiography (STE-TAPSE) in a cross-section of routine cardiac surgery patients. DESIGN: Retrospective, observational study. SETTING: Tertiary, academic referral hospital. PARTICIPANTS: Patients undergoing elective cardiac surgery with intraoperative transesophageal echocardiography (TEE) imaging. INTERVENTIONS: TEE imaging was reviewed and evaluated for the following three different measurements of transthoracic echocardiography-TAPSE surrogates: 2D-TAPSE, 2D-TAPSE-apex, and STE-TAPSE. Statistical analyses, including 2-sample t tests, linear regression, and agreement using the Bland-Altman methods, were performed. MEASUREMENTS AND MAIN RESULTS: Modest correlation was demonstrated between STE-TAPSE and 2D-TAPSE (R2 = 0.37; p < 0.001) and between STE-TAPSE and 2D-TAPSE-apex (R2 = 0.34; p < 0.001). There was good correlation between 2D-TAPSE and 2D-TAPSE-apex (R2 = 0.77, p < 0.001). The Bland-Altman analysis between these methods showed minimal bias: STE-TAPSE and 2D-TAPSE 0.84 mm, STE-TAPSE and 2D-TAPSE-apex 0.14 mm, and 2D-TAPSE and 2D-TAPSE-apex 0.98 mm. However, the agreement was poor, with 95% limits of agreement of -10.67 to 8.99 mm, -10.67 to 10.96 mm, and -4.91 to 6.88 mm, respectively. CONCLUSIONS: Correlation and minimal bias were found between the several proposed TEE surrogates of transthoracic echocardiography-TAPSE; however, there was poor agreement. Therefore, these surrogates are not interchangeable, and each method needs to be separately validated for clinical use to relevant perioperative outcomes.

Assessment of Tricuspid Annular Motion by Speckle Tracking in Anesthetized Patients Using Transesophageal Echocardiography.

BACKGROUND: The perioperative assessment of right ventricular (RV) function remains a challenge. Tricuspid annular plane systolic excursion (TAPSE) using M-mode is a widely used measure of RV function. However, accurate alignment of the ultrasound beam with the direction of annular movement can be difficult with transesophageal echocardiography (TEE) to measure TAPSE, precluding effective use of M-mode to measure annular excursion. Tracking of specular reflectors in the myocardium may provide an angle-independent method to assess annular motion with TEE. We hypothesized that TEE speckle tracking of the lateral tricuspid annular motion represents a comparable measurement to the well-validated M-mode TAPSE on transthoracic echocardiogram (TTE), and may be considered as a reasonable alternative to TAPSE. METHODS: This is a prospective, observational cohort study. We included all patients, who were in sinus rhythm, with a preoperative TTE within 3 months of scheduled cardiac surgery that required intraoperative TEE. Tissue motion annular displacements (TMAD) of the lateral (L), septal (S), and midpoint (M) tricuspid annulus were measured (QLAB Cardiac Motion Quantification; Philips Medical, Andover, MA) after induction of general anesthesia. This was compared to the preoperative M-mode TAPSE on TTE. RESULTS: Seventy-two consecutive patients who met eligibility requirements were enrolled from September to November 2016. Twelve were excluded due to poor image quality, allowing TMAD to be analyzed in 60 patients. TMAD was analyzed offline and TMAD analysis was able to track tricuspid annular motion in all patients. The mean TMAD (L), TMAD (S), and TMAD (M) were 17.4 ± 5.2, 10.2 ± 4.8, and 14.2 ± 4.8 mm, respectively. TMAD (L) showed close correlation with M-mode TAPSE on TTE (r = 0.87, 95% confidence interval, 0.79-0.92; P < .01). All patients with a preoperative TAPSE <17 mm had a TMAD (L) <17 mm, while 71% of those with a TAPSE ≥ 17 mm had a TMAD (L) ≥ 17 mm. There was strong positive correlation between TMAD (L) and intraoperative RV fractional area change (r = 0.86, 95% confidence interval, 0.77-0.91; P < .01). Reproducibility analysis of TMAD within and across observers showed excellent correlation. CONCLUSIONS: TMAD is a quick and angle-independent method to quantitatively assess RV longitudinal function by TEE. It correlates strongly with M-mode TAPSE on TTE. Because TMAD and TAPSE were not simultaneously measured in this study, their correlation is subject to differences in loading conditions, general anesthesia, and changes in the disease process. TMAD may be easily applied in routine clinical settings and its role in the perioperative environment deserves to be further explored.

Three-Dimensional Field Optimization Method: Clinical Validation of a Novel Color Doppler Method for Quantifying Mitral Regurgitation.

BACKGROUND: Assessment of mitral regurgitation (MR) severity by echocardiography is important for clinical decision making, but MR severity can be challenging to quantitate accurately and reproducibly. The accuracy of effective regurgitant orifice area (EROA) and regurgitant volume (RVol) calculated using two-dimensional (2D) proximal isovelocity surface area is limited by the geometric assumptions of proximal isovelocity surface area shape, and both variables demonstrate interobserver variability. The aim of this study was to compare a novel automated three-dimensional (3D) echocardiographic method for calculating MR regurgitant flow using standard 2D techniques. METHODS: A sheep model of ischemic MR and patients with MR were prospectively examined. Patients with a range of severity of MR were examined. EROA and RVol were calculated from 3D color Doppler acquisitions using a novel computer-automated algorithm based on the field optimization method to measure EROA and RVol. For an independent comparison group, the 3D field optimization method was compared with 2D methods for grading MR in an experimental ovine model of MR. RESULTS: Fifteen 3D data sets from nine sheep (open-chest transthoracic echocardiographic data sets) and 33 transesophageal data sets from patients with MR were prospectively examined. For sheep data sets, mean 2D EROA was 0.16 ± 0.05 cm2, and mean 2D RVol was 21.84 ± 8.03 mL. Mean 3D EROA was 0.09 ± 0.04 cm2, and mean 3D RVol was 14.40 ± 5.79 cm3. There was good correlation between 2D and 3D EROA (R = 0.70) and RVol (R = 0.80). For patient data sets, mean 2D EROA was 0.35 ± 0.35 cm2, and mean 2D RVol was 58.9 ± 52.9 mL. Mean 3D EROA was 0.34 ± 0.29 cm2, and mean 3D RVol was 54.6 ± 36.5 mL. There was excellent correlation between 2D and 3D EROA (R = 0.94) and RVol (R = 0.84). Bland-Altman analysis revealed greater interobserver variability for 2D RVol measurements compared with 3D RVol using the 3D field optimization method measurements, but variability was statistically significant only for RVol. CONCLUSIONS: Direct automated measurement of proximal isovelocity surface area region for EROA calculation using real-time 3D color Doppler echocardiography is feasible, with a high correlation to current 2D EROA methods but less variability. This novel automated method provides an accurate and highly reproducible method for calculating EROA.

3-dimensional echocardiography and its role in preoperative mitral valve evaluation.

Echocardiography plays a key role in the preoperative evaluation of mitral valve disease. 3-dimensional echocardiography is a relatively new development that is being used more and more frequently in the evaluation of these patients. This article reviews the available literature comparing the use of this new technology to classic techniques in the assessment of mitral valve pathology. The authors also review some of the novel insights learned from 3-dimensional echocardiography and how they may be used in surgical decision making and planning.

3D transesophageal echocardiography: a review of recent literature 2007-2009.

PURPOSE OF REVIEW: The use of two-dimensional (2D) transesophageal echocardiography (TEE) is nearly universal in cardiac surgical operating rooms around the world. Cardiac anesthesiologists or cardiologists perform these examinations, facilitating significant advancements in surgical techniques by the immediacy and accuracy of intra-operative ultrasound imaging. Three-dimensional (3D) TEE capabilities have been available since the 1990s but penetration has been poor. With the advent of real-time 3D TEE, interest in this technology has increased dramatically. This is a comprehensive review of English language publications in the field from 2007 to 2009. RECENT FINDINGS: This review utilized Pubmed databases, with search strategy based on primary key words: 3D echocardiography, transesophageal echocardiography, cardiac surgery, and/or cardiopulmonary bypass. Three major areas of clinical practice are impacted by the findings of these studies: cardiac valve repair and replacement, assessment of ventricular function, and image guidance for percutaneous procedures. SUMMARY: The review resulted in the conclusion that 3D TEE provides unique and dynamic 3D spatial information that cannot be obtained by 2D TEE or fluoroscopy. In addition to technical and process advancements, future studies should address educational value in terms of acceleration of learning curves, and impact on surgical decision making.