Jelliffe Jeganathan

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.

Now You See Me, Now You Don't

A 60-YEAR-OLD MALE was undergoing radical nephrectomy under transesophageal echocardiographic (TEE) guidance for renal cell carcinoma. The tumor was known to extend to the lumen of the inferior vena cava through the renal vein (Fig 1). During extraction, a large portion of the tumor was dislodged inadvertently and embolized to the superior vena cava. There was immediate significant hemodynamic instability. The patient was resuscitated with multiple bolus doses of inotropes (epinephrine). At the same time, a large and mobile echodensity was visualized in the right atrium (RA) (Fig 2).

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.

Dynamic changes in the ischemic mitral annulus: Implications for ring sizing

Objectives: Contrary to the rest of the mitral annulus, inter-trigonal distance is known to be relatively less dynamic during the cardiac cycle. Therefore, intertrigonal distance is considered a suitable benchmark for annuloplasty ring sizing during mitral valve (MV) surgery. The entire mitral annulus dilates and flattens in patients with ischemic mitral regurgitation (IMR). It is assumed that the fibrous trigone of the heart and the intertrigonal distance does not dilate. In this study, we sought to demonstrate the changes in mitral annular geometry in patients with IMR and specifically analyze the changes in intertrigonal distance during the cardiac cycle. Methods: Intraoperative three-dimensional transesophageal echocardiographic data obtained from 26 patients with normal MVs undergoing nonvalvular cardiac surgery and 36 patients with IMR undergoing valve repair were dynamically analyzed using Philips Qlab ® software. Results: Overall, regurgitant valves were larger in area and less dynamic than normal valves. Both normal and regurgitant groups displayed a significant change in annular area (AA) during the cardiac cycle (P < 0.01 and P < 0.05, respectively). Anteroposterior and anterolateral-posteromedial diameters and inter-trigonal distance increased through systole (P < 0.05 for all) in accordance with the AAs in both groups. However, inter-trigonal distance showed the least percentage change across the cardiac cycle and its reduced dynamism was validated in both cohorts (P > 0.05). Conclusions: Annular dimensions in regurgitant valves are dynamic and can be measured feasibly and accurately using echocardiography. The echocardiographically identified inter-trigonal distance does not change significantly during the cardiac cycle.

Artificial Intelligence in Mitral Valve Analysis

Background: Echocardiographic analysis of mitral valve (MV) has become essential for diagnosis and management of patients with MV disease. Currently, the various software used for MV analysis require manual input and are prone to interobserver variability in the measurements. Aim: The aim of this study is to determine the interobserver variability in an automated software that uses artificial intelligence for MV analysis. Settings and Design: Retrospective analysis of intraoperative three-dimensional transesophageal echocardiography data acquired from four patients with normal MV undergoing coronary artery bypass graft surgery in a tertiary hospital. Materials and Methods: Echocardiographic data were analyzed using the eSie Valve Software (Siemens Healthcare, Mountain View, CA, USA). Three examiners analyzed three end-systolic (ES) frames from each of the four patients. A total of 36 ES frames were analyzed and included in the study. Statistical Analysis: A multiple mixed-effects ANOVA model was constructed to determine if the examiner, the patient, and the loop had a significant effect on the average value of each parameter. A Bonferroni correction was used to correct for multiple comparisons, and P = 0.0083 was considered to be significant. Results: Examiners did not have an effect on any of the six parameters tested. Patient and loop had an effect on the average parameter value for each of the six parameters as expected (P < 0.0083 for both). Conclusion: We were able to conclude that using automated analysis, it is possible to obtain results with good reproducibility, which only requires minimal user intervention.

Recurrent Pulmonary Vein Stenosis After Pulmonary Vein Isolation

Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA Department of Cardio-Thoracic Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands Department of Anesthesia, Peking University Peoples Hospital, Beijing, China Department of Anesthesia, Hospital México, Universidad de Costa Rica, San José, Costa Rica

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.

Neuropeptide Y3-36 incorporated into PVAX nanoparticle improves functional blood flow in a murine model of hind limb ischemia

We generated a novel nanoparticle called PVAX, which has intrinsic antiapoptotic and anti-inflammatory properties. This nanoparticle was loaded with neuropeptide Y3-36 (NPY3-36), an angiogenic neurohormone that plays a central role in angiogenesis. Subsequently, we investigated whether PVAX-NPY3-36 could act as a therapeutic agent and induce angiogenesis and vascular remodeling in a murine model of hind limb ischemia. Adult C57BL/J6 mice (n = 40) were assigned to treatment groups: control, ischemia PBS, ischemia PVAX, ischemia NPY3-36, and Ischemia PVAX-NPY3-36 Ischemia was induced by ligation of the femoral artery in all groups except control and given relevant treatments (PBS, PVAX, NPY3-36, and PVAX-NPY3-36). Blood flow was quantified using laser Doppler imaging. On days 3 and 14 posttreatment, mice were euthanized to harvest gastrocnemius muscle for immunohistochemistry and immunoblotting. Blood flow was significantly improved in the PVAX-NPY3-36 group after 14 days. Western blot showed an increase in angiogenic factors VEGF-R2 and PDGF-β (P = 0.0035 and P = 0.031, respectively) and antiapoptotic marker Bcl-2 in the PVAX-NPY3-36 group compared with ischemia PBS group (P = 0.023). Proapoptotic marker Smad5 was significantly decreased in the PVAX-NPY3-36 group as compared with the ischemia PBS group (P = 0.028). Furthermore, Y2 receptors were visualized in endothelial cells of newly formed arteries in the PVAX-NPY3-36 group. In conclusion, we were able to show that PVAX-NPY3-36 can induce angiogenesis and arteriogenesis as well as improve functional blood flow in a murine model of hind limb ischemia.NEW & NOTEWORTHY Our research project proposes a novel method for drug delivery. Our patented PVAX nanoparticle can detect areas of ischemia and oxidative stress. Although there have been studies about delivering angiogenic molecules to areas of ischemic injury, there are drawbacks of nonspecific delivery as well as short half-lives. Our study is unique because it can specifically deliver NPY3-36 to ischemic tissue and appears to extend the amount of time therapy is available, despite NPY3-36s short half-life.

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

Valvular Heart Disease

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.