Lu Yeh

Hemodynamic Testing of Patient-Specific Mitral Valves Using a Pulse Duplicator: A Clinical Application of Three-Dimensional Printing

OBJECTIVE To evaluate the feasibility of obtaining hemodynamic metrics of echocardiographically derived 3-dimensional printed mitral valve models deployed in a pulse-duplicator chamber. DESIGN Exploratory study. SETTING Tertiary-care university hospital. PARTICIPANTS Percutaneous MitraClip procedure patient. INTERVENTIONS Three-dimensional R-wave gated, full-volume transesophageal echocardiography images were obtained after deployment of the MitraClip device. A high-quality diastolic frame of the mitral valve was segmented using Mimics Innovation Suite and merged with a flange. The data were exported as a stereolithography (.stl) file, and a rigid 3-dimensional model was printed using a MakerBot Replicator 2 printer. A flexible silicone cast then was created and deployed in the pulse-duplicator chamber filled with a blood-mimicking fluid. MEASUREMENTS AND MAIN RESULTS The authors were able to obtain continuous-wave Doppler tracings of the valve inflow with a transesophageal echocardiography transducer. They also were able to generate diastolic ventricular and atrial pressure tracings. Pressure half-time and mitral valve area were computed from these measurements. CONCLUSION This pulse duplicator shows promising applications in hemodynamic testing of patient-specific anatomy. Future modifications to the system may allow for visualization and data collection of gradients across the aortic valve.

Making three-dimensional echocardiography more tangible: a workflow for three-dimensional printing with echocardiographic data

Three-dimensional (3D) printing is a rapidly evolving technology with several potential applications in the diagnosis and management of cardiac disease. Recently, 3D printing (i.e. rapid prototyping) derived from 3D transesophageal echocardiography (TEE) has become possible. Due to the multiple steps involved and the specific equipment required for each step, it might be difficult to start implementing echocardiography-derived 3D printing in a clinical setting. In this review, we provide an overview of this process, including its logistics and organization of tools and materials, 3D TEE image acquisition strategies, data export, format conversion, segmentation, and printing. Generation of patient-specific models of cardiac anatomy from echocardiographic data is a feasible, practical application of 3D printing technology.

Tricuspid annulus: A spatial and temporal analysis

Background: Traditional two-dimensional (2D) echocardiographic evaluation of tricuspid annulus (TA) dilation is based on single-frame measurements of the septolateral (S-L) dimension. This may not represent either the axis or the extent of dynamism through the entire cardiac cycle. In this study, we used real-time 3D transesophageal echocardiography (TEE) to analyze geometric changes in multiple axes of the TA throughout the cardiac cycle in patients without right ventricular abnormalities. Materials and Methods: R-wave-gated 3D TEE images of the TA were acquired in 39 patients undergoing cardiovascular surgery. The patients with abnormal right ventricular/tricuspid structure or function were excluded from the study. For each patient, eight points along the TA were traced in the 3D dataset and used to reconstruct the TA at four stages of the cardiac cycle (end- and mid-systole, end- and mid-diastole). Statistical analyses were applied to determine whether TA area, perimeter, axes, and planarity changed significantly over each stage of the cardiac cycle. Results: TA area (P = 0.012) and perimeter (P = 0.024) both changed significantly over the cardiac cycle. Of all the axes, only the posterolateral-anteroseptal demonstrated significant dynamism (P < 0.001). There was also a significant displacement in the vertical axis between the points and the regression plane in end-systole (P < 0.001), mid-diastole (P = 0.014), and mid-systole (P < 0.001). Conclusions: The TA demonstrates selective dynamism over the cardiac cycle, and its axis of maximal dynamism is different from the axis (S-L) that is routinely measured with 2D TEE.

Assessment of Perioperative Ultrasound Workflow Understanding: A Consensus

OBJECTIVES Understanding of the workflow of perioperative ultrasound (US) examination is an integral component of proficiency. Workflow consists of the practical steps prior to executing an US examination (eg, equipment operation). Whereas other proficiency components (ie, cognitive knowledge and manual dexterity) can be tested, workflow understanding is difficult to define and assess due to its contextual and institution-specific nature. The objective was to define the workflow components of specific perioperative US applications using an iterative process to reach a consensus opinion. DESIGN Expert consensus, survey study. SETTING Tertiary university hospital. PARTICIPANTS This study sought expert consensus among a focus group of 9 members of an anesthesia department with experience in perioperative US. Afterward, 257 anesthesia faculty members from 133 academic centers across the United States were surveyed. INTERVENTIONS A preliminary list of tasks was designed to establish the expectations of workflow understanding by an anesthesiology resident prior to clinical exposure to perioperative US. This list was modified by a focus group through an iterative process. Afterwards, a survey was sent to faculty members nationwide, and Likert scale ratings for each task were obtained and reviewed during a second round. MEASUREMENTS AND MAIN RESULTS Consensus among members of the focus group was reached after 2 iterations. 72 participants responded to the nationwide survey (28%), and consensus was reached after the second round (Cronbachs α = 0.99, ICC = 0.99) on a final list of 46 workflow-related tasks. CONCLUSIONS Specific components of perioperative US workflow were identified. Evaluation of workflow understanding may be combined with cognitive knowledge and manual dexterity testing for assessing proficiency in perioperative US.

An Echodensity in the Sinus of Valsalva

A 60-YEAR-OLD woman was referred to the authors’ institution for surgical treatment of severe aortic valve stenosis with progressive exertional dyspnea. A few months before the current admission, she had been treated in an outside hospital for congestive heart failure. Cardiac catheterization confirmed aortic valve stenosis (aortic valve area 0.9 cm2) and revealed 90% right coronary artery (RCA) ostial stenosis. A bare metal stent was implanted in the RCA. The patient was taken to the operating room for aortic valve replacement.

Low-cost three-dimensional printed phantom for neuraxial anesthesia training: Development and comparison to a commercial model

Neuraxial anesthesia (spinal and epidural anesthesia) procedures have significant learning curves and have been traditionally taught at the bed side, exposing patients to the increased risk associated with procedures done by novices. Simulation based medical education allows trainees to repeatedly practice and hone their skills prior to patient interaction. Wide-spread adoption of simulation-based medical education for procedural teaching has been slow due to the expense and limited variety of commercially available phantoms. Free/Libre/open-source (FLOS) software and desktop 3D printing technologies has enabled the fabrication of low-cost, patient-specific medical phantoms. However, few studies have evaluated the performance of these devices compared to commercially available phantoms. This paper describes the fabrication of a low-cost 3D printed neuraxial phantom based on computed tomorography (CT) scan data, and expert validation data comparing this phantom to a commercially available model. Methods Anonymized CT DICOM data was segmented to create a 3D model of the lumbar spine. The 3D model was modified, placed inside a digitally designed housing unit and fabricated on a desktop 3D printer using polylactic acid (PLA) filament. The model was filled with an echogenic solution of gelatin with psyllium fiber. Twenty-two staff anesthesiologists performed a spinal and epidural on the 3D printed simulator and a commercially available Simulab phantom. Participants evaluated the tactile and ultrasound imaging fidelity of both phantoms via Likert-scale questionnaire. Results The 3D printed neuraxial phantom cost

Evaluation of the quality of transesophageal echocardiography images and verification of proficiency

13 to print and required 25 hours of non-supervised printing and 2 hours of assembly time. The 3D printed phantom was found to be less realistic to surface palpation than the Simulab phantom due to fragility of the silicone but had significantly better fidelity for loss of resistance, dural puncture and ultrasound imaging than the Simulab phantom. Conclusion Low-cost neuraxial phantoms with fidelity comparable to commercial models can be produced using CT data and low-cost infrastructure consisting of FLOS software and desktop 3D printers.

A Tight Spot After Pulmonary Vein Catheter Ablation

Various metrics have been used in curriculum-based TEE training programs to evaluate acquisition of proficiency. However, the quality of task completion, i.e. the final image quality, was subjectively evaluated in these studies. Ideally, the end point metric should be an objective comparison of the trainee-acquired image with a reference ideal image. Therefore, we developed a simulator-based methodology of pre-clinical verification of proficiency (VOP) in trainees by tracking objective evaluation of the final acquired images. We utilized geometric data from the simulator probes to compare image acquisition of anesthesia residents who participated in our structured longitudinal simulator-based TEE educational program in versus ideal image planes determined froma panel of experts. Thirty-three participants completed the study (15 experts, 7 PGY-1, and 11PGY-4). The results of our study demonstrated a significant difference in image capture success rates between learners and experts (X2=14.716, df=2, p<0.001) with the difference between learners (PGY-1 and PGY-4) not being statistically significant (X2=0, df=1, p=1.000). Therefore, our results suggest that novices (i.e. PGY-1 residents) are capable of attaining a level of proficiency comparable to those with modest training (i.e. PGY-4 residents) after completion of a simulation-based training curriculum. However, professionals with years of clinical training (i.e. attending physicians) exhibit a superior mastery of such skills. It is hence feasible to develop a simulator-based VOP program in performance of TEE for junior anesthesia residents.Various metrics have been used in curriculum-based transesophageal echocardiography (TEE) training programs to evaluate acquisition of proficiency. However, the quality of task completion, that is the final image quality, was subjectively evaluated in these studies. Ideally, the endpoint metric should be an objective comparison of the trainee-acquired image with a reference ideal image. Therefore, we developed a simulator-based methodology of preclinical verification of proficiency (VOP) in trainees by tracking objective evaluation of the final acquired images. We utilized geometric data from the simulator probes to compare image acquisition of anesthesia residents who participated in our structured longitudinal simulator-based TEE educational program vs ideal image planes determined from a panel of experts. Thirty-three participants completed the study (15 experts, 7 postgraduate year (PGY)-1 and 11 PGY-4). The results of our study demonstrated a significant difference in image capture success rates between learners and experts (χ2 = 14.716, df = 2, P < 0.001) with the difference between learners (PGY-1 and PGY-4) not being statistically significant (χ2 = 0, df = 1, P = 1.000). Therefore, our results suggest that novices (i.e. PGY-1 residents) are capable of attaining a level of proficiency comparable to those with modest training (i.e. PGY-4 residents) after completion of a simulation-based training curriculum. However, professionals with years of clinical training (i.e. attending physicians) exhibit a superior mastery of such skills. It is hence feasible to develop a simulator-based VOP program in performance of TEE for junior anesthesia residents.

Summative Objective Structured Clinical Examination Assessment at the End of Anesthesia Residency for Perioperative Ultrasound

A 52-YEAR-OLD woman with a history of embolic stroke due to paroxysmal atrial fibrillation was referred to the authors’ institution for epicardial surgical pulmonary vein isolation with left atrial appendage resection. The patient had 2 previous failed pulmonary vein catheter ablations. Dense fibrous tissue surrounding the left upper pulmonary vein was seen during surgery. Transesophageal echocardiography revealed the following image (Fig 1). What is the diagnosis?