257 research outputs found
Editorial: Partial left ventriculectomy for dilated cardiomyopathy in children
AbstractJ Thorac Cardiovasc Surg 1999;117:918–91
Recommended from our members
Robotics and imaging in congenital heart surgery
The initial success seen in adult cardiac surgery with the application of available robotic systems has not been realized as broadly in pediatric cardiac surgery. The main obstacles include extended set-up time and complexity of the procedures, as well as the large size of the instruments with respect to the size of the child. Moreover, while the main advantage of robotic systems is the ability to minimize incision size, for intracardiac repairs, cardiopulmonary bypass is still required. Catheter-based interventions, on the other hand, have expanded rapidly in both application as well as the complexity of procedures and lesions being treated. However, despite the development of sophisticated devices, robotic systems to aid catheter procedures have not been commonly applied in children. In this article, we describe new catheter-like robotic delivery platforms, which facilitate safe navigation and enable complex repairs, such as tissue approximation and fixation, and tissue removal, inside the beating heart. Additional features including the tracking of rapidly moving tissue targets and novel imaging approaches are described, along with a discussion of future prospects for steerable robotic systems
Recommended from our members
3D Ultrasound-Guided Motion Compensation System for Beating Heart Mitral Valve Repair
Beating heart intracardiac procedures promise significant benefits for patients, however, the fast motion of the heart poses serious challenges to surgeons. We present a new 3D ultrasound-guided motion (3DUS) compensation system that synchronizes instrument motion with the heart. The system utilizes the fact that the motion of some intracardiac structures, including the mitral valve annulus, is largely constrained to translation along one axis. This allows the development of a real-time 3DUS tissue tracker which we integrate with a 1 degree-of-freedom actuated surgical instrument, real-time 3DUS instrument tracker, and predictive filter to devise a system with synchronization accuracy of 1.8 mm RMSE. User studies involving the deployment of surgical anchors in a simulated mitral annuloplasty procedure demonstrate that the system increases success rates by over 100%. Furthermore, it enables more careful anchor deployment by reducing forces to the tissue by 50% while allowing instruments to remain in contact with the tissue for longer periods.Engineering and Applied Science
Recommended from our members
Fast Image-Based Model of Mitral Valve Closure for Surgical Planning
Surgical repair of the mitral valve results in better
outcomes than valve replacement, yet diseased valves
are often replaced due to the technical difficulty of the
repair process. A surgical planning system based on
patient-specific medical images that allows surgeons to
simulate and compare potential repair strategies could
greatly improve surgical outcomes. The system must
simulate valve closure quickly and handle the complex
boundary conditions imposed by the chords that tether
the valve leaflets. We have developed a process for
generating a triangulated mesh of the valve surface
from volumetric image data of the opened valve. The
closed position of the mesh is then computed using a
mass-spring model of dynamics. In the mass-spring
model, triangle sides are treated as linear springs
supporting only tension. Chords are also treated as
linear springs, and self-collisions are detected and
handled inelastically. The equations of motion are
solved using implicit numerical integration. The
simulated closed state is compared with an image of the
same valve taken in the closed state to assess accuracy
of the model. The model exhibits rapid valve closure
and is able to predict the closed state of the valve with
reasonable accuracy.Engineering and Applied Science
Late left ventricular dysfunction after anatomic repair of congenitally corrected transposition of the great arteries
ObjectiveEarly results for anatomic repair of congenitally corrected transposition of the great arteries (ccTGA) are excellent. However, the development of left ventricular dysfunction late after repair remains a concern. In this study we sought to determine factors leading to late left ventricular dysfunction and the impact of cardiac resynchronization as a primary and secondary (upgrade) mode of pacing.MethodsFrom 1992 to 2012, 106 patients (median age at surgery, 1.2 years; range, 2 months to 43 years) with ccTGA had anatomic repair. A retrospective review of preoperative variables, surgical procedures, and postoperative outcomes was performed.ResultsIn-hospital deaths occurred in 5.7% (n = 6), and there were 3 postdischarge deaths during a mean follow-up period of 5.2 years (range, 7 days to 18.2 years). Twelve patients (12%) developed moderate or severe left ventricular dysfunction. Thirty-eight patients (38%) were being paced at latest follow-up evaluation. Seventeen patients had resynchronization therapy, 9 as an upgrade from a prior dual-chamber system (8.5%) and 8 as a primary pacemaker (7.5%). Factors associated with left ventricular dysfunction were age at repair older than 10 years, weight greater than 20 kg, pacemaker implantation, and severe neo-aortic regurgitation. Eight of 9 patients undergoing secondary cardiac resynchronization therapy (upgrade) improved left ventricular function. None of the 8 patients undergoing primary resynchronization developed left ventricular dysfunction.ConclusionsLate left ventricular dysfunction after anatomic repair of ccTGA is not uncommon, occurring most often in older patients and in those requiring pacing. Early anatomic repair and cardiac resynchronization therapy in patients requiring a pacemaker could preclude the development of left ventricular dysfunction
Valve-sparing aortic root replacement and remodeling with complex aortic valve reconstruction in children and young adults with moderate or severe aortic regurgitation
ObjectivesThe durability of valve-sparing aortic root procedures with aortic regurgitation due to leaflet disease is questioned. Here, we review our experience in combined aortic root and valve reconstruction in children and young adults.MethodsAll valve-sparing aortic root procedures from 2000 to 2012 were reviewed, and patients with aortic valve repair beyond resuspension were included. Root procedures were classified as replacement with reimplantation, root remodeling, or aortic annular and sinotubular junction stabilization. The primary end point was structural valve deterioration, a composite of aortic valve reoperation and/or moderate or greater regurgitation at follow-up.ResultsThirty-four patients were included during the study period. The surgery consisted of reimplantation in 13 patients, remodeling in 16 patients, and annular and sinotubular junction stabilization in 5 patients. Valve repair consisted of leaflet procedures in 26 patients and subannular reduction in 15 patients. During a median follow-up of 4.2 months (range, 2 weeks-8 years), there were 5 reoperations for aortic valve replacement due to aortic regurgitation, and 2 patients presented with moderate or greater regurgitation. Freedom from structural valve deterioration was 70.1% ± 10.3% at 1 year and remained stable thereafter, although it was significantly worse in the reimplantation group (P = .039). A more severe degree of preoperative aortic regurgitation (P = .001) and smaller graft to aortic annulus ratio (P = .003) were predictors of structural valve deterioration.ConclusionsValve-sparing root and valve reconstruction can be done with low operative risk and allows valve preservation in most patients. These data should question the assumption that reimplantation is superior when associated with complex valve reconstruction
Recommended from our members
Mitral Annulus Segmentation From Three-Dimensional Ultrasound
An accurate and reproducible segmentation of the mitral valve annulus from 3D ultrasound is useful to clinicians and researchers in applications such as pathology diagnosis and mitral valve modeling. Current segmentation methods, however, are based on 2D information, resulting in inaccuracies and a lack of spatial coherence. We present a segmentation algorithm which, given a single user-specified point near the center of the valve, uses maxflow and active contour methods to delineate the annulus geometry in 3D. Preliminary comparisons to manual segmentations and a sensitivity study show the algorithm is both accurate and robust.Engineering and Applied Science
Recommended from our members
Mass-Spring Model for Simulation of Heart Valve Tissue Mechanical Behavior
Heart valves are functionally complex, making surgical repair difficult. Simulation-based surgical planning could facilitate repair, but current finite element (FE) studies are prohibitively slow for rapid, clinically oriented simulations. Mass-spring (M-S) models are fast but can be inaccurate. We quantify speed and accuracy differences between an anisotropic, nonlinear M-S and an efficient FE membrane model for simulating both biaxial and pressure loading of aortic valve (AV) leaflets. The FE model incurs approximately 10 times the computational cost of the M-S model. For simulated biaxial loading, mean error in normal strains is <1% for both FE and M-S models for equibiaxial loading but increases for non-equibiaxial states for the M-S model (7%). The M-S model was less able to simulate shear behavior, with mean strain error of approximately 80%. For pressurized AV leaflets, the M-S model predicts similar leaflet dimensions to the FE model (within 2.6%), and the coaptation zone is similar between models. The M-S model simulates in-plane behavior of AV leaflets considerably faster than the FE model and with only minor differences in the deformed mesh. While the M-S model does not allow explicit control of shear response, shear does not strongly influence shape of the simulated AV under pressure.Engineering and Applied Science
Recommended from our members
Mitochondrial transplantation for therapeutic use
Mitochondria play a key role in the homeostasis of the vast majority of the body’s cells. In the myocardium where mitochondria constitute 30 % of the total myocardial cell volume, temporary attenuation or obstruction of blood flow and as a result oxygen delivery to myocardial cells (ischemia) severely alters mitochondrial structure and function. These alterations in mitochondrial structure and function occur during ischemia and continue after blood flow and oxygen delivery to the myocardium is restored, and significantly decrease myocardial contractile function and myocardial cell survival. We hypothesized that the augmentation or replacement of mitochondria damaged by ischemia would provide a mechanism to enhance cellular function and cellular rescue following the restoration of blood flow. To test this hypothesis we have used a model of myocardial ischemia and reperfusion. Our studies demonstrate that the transplantation of autologous mitochondria, isolated from the patient’s own body, and then directly injected into the myocardial during early reperfusion augment the function of native mitochondria damaged during ischemia and enhances myocardial post-ischemic functional recovery and cellular viability. The transplanted mitochondria act both extracellularly and intracellularly. Extracellularly, the transplanted mitochondria enhance high energy synthesis and cellular adenosine triphosphate stores and alter the myocardial proteome. Once internalized the transplanted mitochondria rescue cellular function and replace damaged mitochondrial DNA. There is no immune or auto-immune reaction and there is no pro-arrhythmia as a result of the transplanted mitochondria. Our studies and those of others demonstrate that mitochondrial transplantation can be effective in a number of cell types and diseases. These include cardiac and skeletal muscle, pulmonary and hepatic tissue and cells and in neuronal tissue. In this review we discuss the mechanisms leading to mitochondrial dysfunction and the effects on cellular function. We provide a methodology for the isolation of mitochondria to allow for clinical relevance and we discuss the methods we and others have used for the uptake and internalization of mitochondria. We foresee that mitochondrial transplantation will be a valued treatment in the armamentarium of all clinicians and surgeons for the treatment of varied ischemic disorders, mitochondrial diseases and related disorders
- …