Biomedical subjects

Nathan E Green

Publications and source records attributed to Nathan E Green.

4 recordsLinked to original sources

PubMed2005

Angiographic views used for percutaneous coronary interventions: a three-dimensional analysis of physician-determined vs. computer-generated views.

The goal of this study was to determine the severity of vessel foreshortening in standard angiographic views used during percutaneous coronary intervention (PCI). Coronary angiography is limited by its two-dimensional (2D) representation of three-dimensional (3D) structures. Vessel foreshortening in angiographic images may cause errors in the assessment of lesions or the selection and placement of stents. To date, no technique has existed to quantify these 2D limitations or the performance of physicians in selecting angiographic views. Stent deployment was performed in 156 vessel segments in 149 patients. Using 3D reconstruction models of each patient's coronary tree, vessel foreshortening was measured in the actual working view used for stent deployment. A computer-generated optimal view was then identified for each vessel segment and compared to the working view. Vessel foreshortening ranged from 0 to 50% in the 156 working views used for stent deployment and varied by coronary artery and by vessel segment within each artery. In general, views of the mid circumflex artery were the most foreshortened and views of the right coronary artery were the least foreshortened. Expert-recommended views frequently resulted in more foreshortening than computer-generated optimal views, which had only 0.5% +/- 1.2% foreshortening with < 2% overlap for the same 156 segments. Optimal views differed from the operator-selected working views by > or = 10 degrees in over 90% of vessels and frequently occurred in entirely different imaging quadrants. Vessel foreshortening occurs frequently in standard angiographic projections during stent deployment. If unrecognized by the operator, vessel foreshortening may result in suboptimal clinical results. Modifications to expert-recommended views using 3D reconstruction may improve visualization and the accuracy of stent deployment. These results highlight the limitations of 2D angiography and support the development of real-time 3D techniques to improve visualization during PCI.

Adult↗

PubMed2004

Initial clinical experience with intracardiac echocardiography in guiding balloon mitral valvuloplasty: technique, safety, utility, and limitations.

The objective of this study was to examine the feasibility and technique of intracardiac echocardiography during percutaneous balloon mitral valvuloplasty. Echocardiographic imaging is commonly used during mitral valvuloplasty. Intracardiac echocardiography is a newer technology that may provide superior imaging during complex valvular interventions. Intracardiac echocardiography and transthoracic echocardiography were performed in 19 patients undergoing percutaneous balloon mitral valvuloplasty. Intracardiac ultrasound images were obtained via the femoral vein in all patients. Imaging projections and catheter locations that were useful for the performance of mitral valvuloplasty were defined. Intracardiac echocardiography guided transseptal puncture, augmented the assessment of valve apparatus deformity, facilitated balloon positioning across the mitral valve, and permitted postprocedural valvular assessment including identification of mitral regurgitation with color Doppler. Intracardiac echocardiography provided essential imaging guidance and procedural monitoring during percutaneous mitral valvuloplasty.

Adult↗

PubMed2004

Three-dimensional vascular angiography.

Traditional angiography of the vasculature is limited by its 2-dimensional projection of complex 3-dimensional structures and the consequent imaging artifacts that interfere with visualization. During the last 10 years, technologies capable of minimizing the shortcomings of traditional angiography have been developed and are now in clinical use. Rotational angiography and 3-dimensional imaging are 2 of these powerful tools and, together, represent a major advance in the angiographic diagnosis and treatment of patients with coronary, cerebral, and peripheral vascular disease.

Cardiovascular Diseases↗

PubMed2004

Three-dimensional analysis of in vivo coronary stent--coronary artery interactions.

Stent implantation results in important three-dimensional (3D) changes in arterial geometry which may be associated with adverse events. Previous attempts to quantify these 3D changes have been limited by two-dimensional techniques. Using a 3D reconstruction technique, vessel curvatures at end-diastole (ED) and end-systole (ES) were measured before and after stent placement of 100 stents (3 stent cell designs, 6 stent types). After stenting, the mean curvature at ED and ES decreased by 22 and 21%, respectively, and represents a straightening effect on the treated vessel. This effect was proportional to the amount of baseline curvature as high vessel curvature predicted more profound vessel straightening. When analyzed by stent cell design, closed-cell stents resulted in more vessel straightening than other designs (open cell or modified slotted tubes). Stent implantation resulted in the transmission of shape changes to stent ends and generated hinge points or buckling. Stent implantation creates 3D changes in arterial geometry which can be quantified using a 3D reconstruction technique.

Blood Vessel Prosthesis Implantation↗