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.

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.