Khurram Owais

Three-Dimensional Printing of Mitral Valve Using Echocardiographic Data

Three-dimensional (3D) printing has steadily gained traction as a clinical tool. Current applications include developing patient-specific implants, prostheses, and realistic anatomic models for surgical education and planning [(1,2)][1]. In cardiac surgery, patient-specific 3D models of hearts with

Echocardiography derived three-dimensional printing of normal and abnormal mitral annuli

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.

Cardiac Output Calculation and Three-Dimensional Echocardiography

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.

Three-Dimensional Printing of the Mitral Annulus Using Echocardiographic Data: Science Fiction or in the Operating Room Next Door?

Address reprint requests to Feroze Mahmood, MD. Beth Israel Deaconess Medical Center One Deaconess Road, CC-470, Boston, MA 02215. E-mail: hwarraic@bidmc.harvard.edu

Oxidative Stress and Nerve Function After Cardiopulmonary Bypass in Patients With Diabetes

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.

Multimodal Perioperative Ultrasound Course for Interns Allows for Enhanced Acquisition and Retention of Skills and Knowledge.

The ability to apply perioperative ultrasound techniques is a desirable skill for clinicians. We implemented a multimodal 13-day basic ultrasound course for 6 anesthesia interns. Their scores on a knowledge test increased after the course and were sustained and similar to those of 6 senior residents 90 days later. The interns acquired images of the heart in volunteers with little assistance after the course. They maintained their ability to acquire echocardiographic images on a simulator 90 days later with kinematic measures superior to the same seniors. Through this course, interns gained knowledge and skills equal to or greater than seniors.

Tricuspid Annulus: A Three-Dimensional Deconstruction and Reconstruction

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.

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.

Left Atrial Appendage, Intraoperative Echocardiography, and the Anesthesiologist.

From the *Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA; and †Department of Surgery, Division of Cardiac Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA. Address reprint requests to Feroze Mahmood, MD, One Deaconess Road, CC 470, Boston, MA 02215. E-mail: fmahmood@bidmc. harvard.edu

Cardiopulmonary Bypass Decreases Activation of the Signal Transducer and Activator of Transcription 3 (STAT3) Pathway in Diabetic Human Myocardium

BACKGROUND Cardiopulmonary bypass (CPB) is associated with increased myocardial oxidative stress and apoptosis in diabetic patients. A mechanistic understanding of this relationship could have therapeutic value. To establish a possible mechanism, we compared the activation of the cardioprotective signal transducer and activator of transcription 3 (STAT3) pathway between patients with uncontrolled diabetes (UD) and nondiabetic (ND) patients. METHODS Right atrial tissue and serum were collected before and after CPB from 80 patients, 39 ND and 41 UD (HbA1c ≥ 6.5), undergoing cardiac operations. The samples were evaluated with Western blotting, immunohistochemistry, and microarray. RESULTS On Western blot, leptin levels were significantly increased in ND post-CPB (p < 0.05). Compared with ND, the expression of Janus kinase 2 and phosphorylation (p-) of STAT3 was significantly decreased in UD (p < 0.05). The apoptotic proteins p-Bc12/Bc12 and caspase 3 were significantly increased (p < 0.05), antiapoptotic proteins Mcl-1, Bcl-2, and p-Akt were significantly decreased (p < 0.05) in UD compared with ND. The microarray data suggested significantly increased expression of interleukin-6 R, proapoptotic p-STAT1, caspase 9, and decreased expression of Bc12 and protein inhibitor of activated STAT1 antiapoptotic genes (p = 0.05) in the UD patients. The oxidative stress marker nuclear factor-κB was significantly higher (p < 0.05) in UD patients post-CPB compared with the pre-CPB value, but was decreased, albeit insignificantly, in ND patients post-CPB. CONCLUSIONS Compared with ND, UD myocardium demonstrated attenuation of the cardioprotective STAT3 pathway. Identification of this mechanism offers a possible target for therapeutic modulation.