Rapid prototyping: a new tool in understanding and treating structural heart disease.

As the appreciation of structural heart disease in children and adults has increased and as catheter-based closure procedures are now being performed in clinical practice, cardiovascular physicians have multiple compelling new reasons to better understand cardiac anatomic and spatial relationships. Current 2-dimensional imaging techniques remain limited both in their ability to represent the complex 3-dimensional relationships present in structural heart disease and in their capacity to adequately facilitate often complex corrective procedures. This review discusses the cardiovascular applications of rapid prototyping, a new technology that may not only play a significant role in the planning of catheter-based interventions but also may serve as a valuable educational tool to enhance the medical community's understanding of the many forms of structural heart disease.

Quantitative assessment of the conformational change in the femoropopliteal artery with leg movement.

BACKGROUND: The unique physical forces exerted on the femoropopliteal (FP) artery during movement have been implicated in the high rates of restenosis and stent fracture in this artery. Conformational changes in the FP artery during movement are important surrogates of these forces. This study sought to quantify the conformational change in the FP artery between the straight-leg (SL) and crossed-leg (CL) positions. METHODS: Using paired angiographic images of overlapping segments of the FP artery in SL and CL positions from patients with peripheral arterial disease, 3-D models of individual segments were generated and subsequently fused to create a 3-D model of the entire FP artery in both leg positions. Based on these 3-D models, the following parameters in the SL and CL positions were quantitatively assessed for the superficial femoral artery (SFA), popliteal artery (PA), and FP artery (i.e., SFA and PA): length, curvature, torsion, twist angle, and development of new flexion angles = 15 degrees. RESULTS: In nine male patients with a mean age of 57 +/- 10.2 years, angiography was performed in 10 FP arteries, with successful generation of 3-D models for all vessels. Movement from the SL to the CL position for the SFA, PA, and FP artery was associated with (a) a mean shortening of 18.2 mm (P = 0.002), 32.2 mm (P < 0.001), and 50.3 mm (P < 0.001), respectively; (b) a mean increase in curvature of 0.04 cm(-1) (P = 0.012), 0.2 cm(-1) (P < 0.001), and 0.11 cm(-1) (P < 0.001), respectively; (c) and small absolute changes in mean torsion of 0.034 cm(-1) (P = 0.48), 0.006 cm(-1) (P < 0.001), and 0.057 cm(-1) (P < 0.001), respectively. The same leg movement was associated with a mean twist angle of 45.6 degrees +/- 27.9 degrees (range of 17.4 degrees-103.4 degrees ) and 61.1 degrees +/- 31.9 degrees (range of 20.5 degrees-101.1 degrees ) for the SFA and PA, respectively. Compared to the SL position, the CL position induced a single flexion point (FxP) =15 degrees in the SFA in two patients, and a mean of 2.4 FxPs =15 degrees (range 1-5) in the PA. CONCLUSIONS: Significant changes in length, curvature, and twist occur in the PA and significant but more modest changes in length and twist occur in the SFA during movement from the SL to the CL position. This data has important implications for endovascular therapies that are used to treat disease in the FP artery.

The future cardiac catheterization laboratory.

This article describes the major components in the future cardiac catheterization laboratory to facilitate cardiac interventions for both coronary artery and structural heart diseases.

Use of rapid prototyping in the care of patients with structural heart disease.

Advances in surgery, interventional techniques, and critical care have allowed more than 90% of children born with structural heart defects to survive into adulthood. In addition, advances in imaging technology continue to raise awareness of hemodynamically significant intracardiac shunt lesions in both adults and children. Adult cardiologists are now faced with the daunting task of caring for patients with complex structural heart lesions, a population subset that at one time was exclusively cared for by pediatric cardiologists and congenital heart disease specialists. Given the wide range of anatomic complexity present in patients with structural heart disease, the definition and anatomic clarification of their structural abnormalities through high-quality noninvasive imaging has become paramount. Current two-dimensional imaging techniques, however, remain limited in their ability to effectively illustrate the complex three-dimensional relationships present in structural heart disease. Rapid prototyping, a process by which three-dimensional digital surface models are converted into physical models, represents the next evolution in advanced image processing and may serve as a means to improve our understanding of the many forms of structural heart disease. Ultimately, the technology may be used to enhance the level of care provided to the growing number of patients with structural heart defects. We recently reviewed the novel cardiovascular application of rapid prototyping. This review examines the expanded applications of rapid prototyping in the care and treatment of adult patients with structural heart disease.

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.

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.

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.