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Feasibility of off-pump ASD closure using real-time 3-D echocardiography
Stephen W Downing1, William R Herzog, Michael C McElroy
1University of Maryland School of Medicine, Baltimore, MD, USA. Sdowning@smail.umaryland.edu
Insights
Real-time 3-D echocardiography offers surgeons a new way to visualize cardiac structures. This technology proved sufficient for guiding atrial septal defect (ASD) closures without traditional open-heart surgery.
Area of Science:
- Cardiovascular Surgery
- Medical Imaging Technology
- Echocardiography
Background:
- Minimally invasive cardiac surgery requires advanced visualization techniques.
- Conventional echocardiography and 3-D CT/echo lack real-time capabilities for surgical guidance.
- Real-time 3-D echocardiography has emerged as a potential solution for intraoperative visualization.
Purpose of the Study:
- To evaluate the efficacy of real-time 3-D echocardiography for surgical visualization.
- To determine if this technology can replace optical visualization during procedures like atrial septal defect (ASD) closure.
- To assess the image quality, depth perception, and resolution for surgical guidance.
Main Methods:
- A prototype real-time 3-D echocardiographic system was tested on a reference model.
- Image resolution and optimal imaging parameters were determined.
- The system was used to guide the closure of five porcine ASDs under echocardiographic visualization.
Main Results:
- Optimal imaging was achieved with the probe 4-6 cm from the target at specific angles.
- The system demonstrated adequate spatial and temporal resolution for surgical tasks.
- All five porcine ASDs were successfully closed using only echo guidance.
Conclusions:
- Real-time 3-D echocardiography provides sufficient anatomical and spatial information for surgical guidance.
- This technology shows promise for enabling minimally invasive cardiac procedures.
- The system can potentially serve as a substitute for optical visualization in specific surgical applications.
Background:
If surgeons could "see " through blood and cardiac chamber walls, it would ultimately be unnecessary to open the heart or use cardiopulmonary bypass to perform procedures such as atrial septal defect (ASD) closure or mitral valve repair. Conventional echocardiography generates cross-sectional images that are not satisfactory as the only visualization for surgical procedures, and current 3-Dimensional (3-D) CT and echo systems take several minutes to compose and process a single still frame. Recently, however, the first system for real-time 3-D echocardiography has been developed. This study examines whether real-time 3-D echocardiography can provide images of sufficient anatomic definition, depth perception, and image resolution to substitute for optical visualization in performing ASD closures.
Methods:
A prototype Volumetrics 3-D echocardiographic system was evaluated in a water bath on a complex-surfaced standard reference model to determine the image resolution and define the ideal imaging parameters. A static image and views of sutures being placed with an endoscopic needle driver and two commercial suture placement devices were evaluated at multiple angles and distances from the target. The resulting images were graded by a blinded reviewer. Once the best imaging parameters were determined, five porcine ASDs were closed with interrupted sutures, running sutures, or a pursestring suture using only echo visualization.
Results:
The highest quality images were obtained with the probe at a distance of 4-6 cm and at angles perpendicular or 45 degrees forward to the target. Spatial and temporal resolutions were adequate to suture all ASDs closed under only echo guidance.
Conclusions:
The evaluated real-time 3-D echo system provided adequate spatial and temporal information to act as a guide for surgical procedures.