Publications

BACKGROUND: Chronic hyperglycemia has been associated with increased oxidative stress in skeletal muscle and sympathetic nerve dysfunction. We investigated the effect of chronic hyperglycemia on the myocardium of patients with uncontrolled diabetes (UD) compared with patients with well-controlled diabetes (CD) and patients without diabetes (ND) after cardioplegic cardiopulmonary bypass (CP/CPB) with acute intraoperative glycemic control.

METHODS: Atrial tissue and serum were collected from 47 patients (ND=18 with glycated hemoglobin [HbA1c] of 5.8±0.2; CD=8 with HbA1c of 6.1±0.1; with UD=21 with HbA1c=9.6±0.5) before and after CP/CPB for immunoblotting, protein oxidation assays, immunohistochemical evaluation, and microarray analysis.

RESULTS: The uncontrolled group had increased total protein oxidation (p<0.05) and decreased levels of antioxidative enzyme manganese superoxide dismutase (MnSOD) (p<0.05) after CP/CPB compared with the controlled group. Collagen staining revealed increased fibrosis in patients with UD (p<0.05) compared with patients with CD and patients without diabetes. The uncontrolled group also showed a decrease in the neurogenic and angiogenic markers nerve growth factor (NGF) (p<0.05), neurotrophin (NT)-3 (p<0.05), and platelet-derived growth factor (PDGF)-β (p<0.05) compared with the other groups after CP/CPB. Atrial and serum microarray analysis showed increased oxidative stress and sympathetic nerve damage, increased fibrosis, and a decrease in angiogenesis in patients with UD (p<0.03) compared with patients without diabetes.

CONCLUSIONS: CP/CPB led to higher oxidative stress in patients with UD before surgical intervention, even after normal glucose levels were maintained intraoperatively. Thus, controlled HbA1C in addition to acute intraoperative glucose control may be a more suitable end point for patients with diabetes undergoing cardiac operations.

BACKGROUND: Transesophageal echocardiography (TEE) is a complex endeavor involving both motor and cognitive skills. Current training requires extended time in the clinical setting. Application of an integrated approach for TEE training including simulation could facilitate acquisition of skills and knowledge.

METHODS: Echo-naive nonattending anesthesia physicians were offered Web-based echo didactics and biweekly hands-on sessions with a TEE simulator for 4 weeks. Manual skills were assessed weekly with kinematic analysis of TEE probe motion and compared with that of experts. Simulator-acquired skills were assessed clinically with the performance of intraoperative TEE examinations after training. Data were presented as median (interquartile range).

RESULTS: The manual skills of 18 trainees were evaluated with kinematic analysis. Peak movements and path length were found to be independent predictors of proficiency (P < 0.01) by multiple regression analysis. Week 1 trainees had longer path length (637 mm [312 to 1,210]) than that of experts (349 mm [179 to 516]); P < 0.01. Week 1 trainees also had more peak movements (17 [9 to 29]) than that of experts (8 [2 to 12]); P < 0.01. Skills acquired from simulator training were assessed clinically with eight additional trainees during intraoperative TEE examinations. Compared with the experts, novice trainees required more time (199 s [193 to 208] vs. 87 s [83 to 16]; P = 0.002) and performed more transitions throughout the examination (43 [36 to 53] vs. 21 [20 to 23]; P = 0.004).

CONCLUSIONS: A simulation-based TEE curriculum can teach knowledge and technical skills to echo-naive learners. Kinematic measures can objectively evaluate the progression of manual TEE skills.

OBJECTIVE: In this study, the authors sought to investigate the extent and timing of changes in mitral annular area during the cardiac cycle. Particularly, the authors assessed whether these changes were limited to the posterior part of the annulus or were more global in nature.

DESIGN: Prospective, observational study

SETTING: Tertiary care university hospital

PARTICIPANTS: Twenty three patients undergoing non-valvular cardiac surgery and 3 patients undergoing vascular procedures.

INTERVENTIONS: Intraoperative 3-dimensional transesophageal echocardiographic data obtained from patients with normal mitral valves undergoing non-valvular cardiac surgery were analyzed geometrically. Annular areas and diameters were measured during various stages of the cardiac cycle. Intertrigonal distance also was measured using 3D data.

MEASUREMENTS AND MAIN RESULTS: Both anterior and posterior portions of the mitral annulus demonstrated dynamism throughout the cardiac cycle. The expansion phase ranged from mid-systole to early-diastole, whereas mid-diastole to early-systole was characterized by an annular contraction phase. Area changes were contributed equally by anterior and posterior parts of the annulus. Annular dimensions increased in accordance with mitral annular area (p<0.05). Echocardiographically-identified intertrigonal distance showed the least delta change.

CONCLUSIONS: Both the anterior and posterior parts of the annulus contribute to changes in mitral annular area, which undergoes discrete expansion and contraction phases that extend into both systole and diastole. Compared to other annular dimensions, the echocardiographically-identified intertrigonal distance does not change significantly during the cardiac cycle.

AIMS AND OBJECTIVES: The objective of this study was to assess the clinical feasibility of using echocardiographic data to generate three-dimensional models of normal and pathologic mitral valve annuli before and after repair procedures.

MATERIALS AND METHODS: High-resolution transesophageal echocardiographic data from five patients was analyzed to delineate and track the mitral annulus (MA) using Tom Tec Image-Arena software. Coordinates representing the annulus were imported into Solidworks software for constructing solid models. These solid models were converted to stereolithographic (STL) file format and three-dimensionally printed by a commercially available Maker Bot Replicator 2 three-dimensional printer. Total time from image acquisition to printing was approximately 30 min.

RESULTS: Models created were highly reflective of known geometry, shape and size of normal and pathologic mitral annuli. Post-repair models also closely resembled shapes of the rings they were implanted with. Compared to echocardiographic images of annuli seen on a computer screen, physical models were able to convey clinical information more comprehensively, making them helpful in appreciating pathology, as well as post-repair changes.

CONCLUSIONS: Three-dimensional printing of the MA is possible and clinically feasible using routinely obtained echocardiographic images. Given the short turn-around time and the lack of need for additional imaging, a technique we describe here has the potential for rapid integration into clinical practice to assist with surgical education, planning and decision-making.

OBJECTIVES: Web and simulation technology may help in creating a transesophageal echocardiography (TEE) curriculum. The authors discuss the educational principles applied to developing and implementing a multimodal TEE curriculum.

DESIGN AND SETTING: The authors modified a pilot course based on principles for effective simulation-based education. Key curricular elements were consistent with principles for effective simulation-based education: (1) clear goals and carefully structured objectives, (2) conveniently accessed, graduated, longitudinal instruction, (3) a protected and optimal learning environment, (4) repetition of concepts and technical skills, (5) progressive expectations for understanding and skill development, (6) introduction of abnormalities after understanding of normal anatomy and probe manipulation is achieved, (7) live learning sessions that are customizable to meet learner needs and individualized proctoring in skill sessions, (8) use of multiple approaches to teaching, (9) regular and relevant feedback, and (10) application of performance and compliance measures.

PARTICIPANTS: Fifty-five learners participated in a curriculum with web-based modules, live teaching, and simulation practice between August 2011 and May 2013.

CONCLUSION: It is possible to develop and implement an integrated, multimodal TEE curriculum supported by educational theory. The authors will explore the transferability of this approach to intraoperative TEE on live patients.

BACKGROUND: Before clinical manifestation of regurgitation, the tricuspid annulus dilates and flattens when right ventricular dysfunction is potentially reversible. That makes the case for a prophylactic tricuspid annuloplasty even in the absence of significant tricuspid regurgitation. Owing to the appreciation of the favorable prognostic value of tricuspid annuloplasty, the geometry of the normal tricuspid annulus merits critical analysis.

METHODS: Three-dimensional transesophageal echocardiographic data from 26 patients were analyzed using Image Arena (TomTec, Munich, Germany) software. Cartesian coordinate data from tricuspid annuli were exported to MATLAB (Mathworks, Natick, MA) for further processing. Annular metrics related to size, shape, and motion were computed.

RESULTS: The tricuspid annulus demonstrated significant changes in area (p<0.01) and perimeter (p<0.03) during the cardiac cycle, with maximum values attained at end diastole. There was significant correlation between two- and three-dimensional area changes, indicating true expansion in the annulus. The anterolateral region of the annulus demonstrated the greatest dynamism (p<0.01), and the anteroseptal region showed the least. The anteroseptal region also displayed the most nonplanarity in the annulus. In addition, vertical translational motion was observed, with a mean distance of 11.3±3.7 mm between end systolic and end diastolic annular centroids.

CONCLUSIONS: The tricuspid annulus is a dynamic, multiplanar structure with heterogeneous regional behavior. These characteristics should be taken into account for optimal annuloplasty device design and efficacy.

OBJECTIVE: To compare the determination of stroke volume (SV) and cardiac output (CO) using 2-dimensional (2D) versus 3-dimensional (3D) transesophageal echocardiography (TEE).

DESIGN: Prospective observational study.

SETTING: Tertiary care university hospital.

PARTICIPANTS: 35 patients without structural valve abnormalities undergoing isolated coronary artery bypass grafting.

INTERVENTIONS: Left ventricular outflow tract (LVOT) diameter determined with 2D TEE was used to estimate LVOT cross-sectional area (CSALVOT). LVOT area was measured directly with 3D TEE by planimetry on an en face view. SV and CO were calculated for both methods using the continuity equation.

MEASUREMENTS AND MAIN RESULTS: The area of the LVOT differed significantly between methods, being significantly larger in the 3D method (3.57±0.70 cm(2)v 3.98±0.93 cm(2)) . This resulted in a 10% lower CO with the 2D method of LVOT area estimation.

CONCLUSIONS: LVOT area is underestimated with the single- axis 2D method when compared with 3D planimetered area. This results in a CO that is approximately 10% lower with the 2D method.