Adam Hansgen

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

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.

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.

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.

Initial clinical experience of selective coronary angiography using one prolonged injection and a 180° rotational trajectory

Evaluate the safety of prolonged coronary injections during a rotational acquisition covering 180°.

Rotational angiography (RA) and three-dimensional imaging (3-DRA): an available clinical tool

Being able to accurately choose an optimal view for stent positioning, non foreshortened length and to avoid side branches is imperative during therapeutic procedures. Traditional imaging limitations may include the selection of an incorrectly sized stent, inaccurate placement, and/or the need for additional stents. With the use of newer acquisition techniques and three-dimensional (3-D) modeling/reconstructions this can be minimized. We present a case in which with the assistance of 3-D and its computer derived optimal view, and optimal length, a significant amount of vessel foreshortening was eliminated therefore improving the procedural outcome.

Safety and efficacy of dual-axis rotational coronary angiography vs. standard coronary angiography.

Objective: To determine the safety and efficacy of dual‐axis rotational coronary angiography (DARCA) by directly comparing it to standard coronary angiography (SA). Background: Standard coronary angiography (SA) requires numerous fixed static images of the coronary tree and has multiple well‐documented limitations. Dual‐axis rotational coronary angiography (DARCA) is a new rotational acquisition technique that entails simultaneous LAO/RAO and cranial/caudal gantry movement. This technological advancement obtains numerous unique images of the left or right coronary tree with a single coronary injection. We sought to assess the safety and efficacy of DARCA as well as determine DARCAs adequacy for CAD screening and assessment. Methods: Thirty patients underwent SA following by DARCA. Contrast volume, radiation dose (DAP) and procedural time were recorded for each method to assess safety. For DARCA acquisitions, blood pressure (BP), heart rate (HR), symptoms and any arrhythmias were recorded. All angiograms were reviewed for CAD screening adequacy by two independent invasive cardiologists. Results: Compared to SA, use of DARCA was associated with a 51% reduction in contrast, 35% less radiation exposure, and 18% shorter procedural time. Both independent reviewers noted DARCA to be at least equivalent to SA with respect to the ability to screen for CAD. Conclusion: DARCA represents a new angiographic technique which is equivalent in terms of image quality and is associated with less contrast use, radiation exposure, and procedural time than SA.

Rotational vs. standard coronary angiography: An image content analysis

Objective: To evaluate the clinical utility of images acquired from rotational coronary angiographic (RA) acquisitions compared to standard “fixed” coronary angiography (SA). Background: RA is a novel angiographic modality that has been enabled by new gantry systems that allow calibrated automatic angiographic rotations and has been shown to reduce radiation and contrast exposure compared to SA. RA provides a dynamic multiple‐angle perspective of the coronaries during a single contrast injection. Methods: The screening adequacy, lesion assessment, and a quantitative coronary analysis (QCA) of both SA and RA were compared by independent blinded review in 100 patients with coronary artery disease (CAD). Results: SA and RA recognize a similar total number of lesions (P = 0.61). The qualitative assessment of lesion characteristics and severity between modalities was comparable and lead to similar clinical decisions. Visualization of several vessel segments (diagonal, distal RCA, postero‐lateral branches and posterior‐descending) was superior with RA when compared to SA (P < 0.05). A QCA comparison (MLD, MLA, LL, % DS) revealed no difference between SA and RA. The volume of contrast (23.5 ± 3.1 mL vs. 39.4 ± 4.1; P = 0.0001), total radiation exposure (27.1 ± 4 vs. 32.1 ± 3.8 Gycm2; P = 0.002) and image acquisition time (54.3 ± 36.8 vs. 77.67 ± 49.64 sec; P = 0.003) all favored RA. Conclusion: Coronary lesion assessment, coronary screening adequacy, and QCA evaluations are comparable in SA and RA acquisition modalities in the diagnosis of CAD however RA decreases contrast volume, image acquisition time, and radiation exposure.

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. Cathet Cardiovasc Interv 2004;63:385–394.

Enhanced stent visualization: A case series demonstrating practical applications during PCI

BACKGROUND Visualization of coronary stents is increasingly challenging due to the reduction in stent strut thickness to improve deliverability. On the other hand stent expansion and precise implantation in the target vessel are important in optimizing short and long-term outcomes of stent-based revascularization. Stentboost Subtract is a novel X-ray technique that improves visualization of deployed stents in the coronary arteries. Using motion compensation and integration of multiple non-contrast projection images from a fixed gantry position, this new technique depicts stent morphology allowing assessment of stent expansion and extent of overlap with adjacent stents. We present a case series in which enhanced stent visualization (ESV) facilitated interventions. METHODS The clinical and angiographic characteristics of 6 cases utilizing ESV were reviewed. All ESV acquisitions in this case series utilized an 8 in. field of view (FOV), 3 ml/sec. for a total of 6 ml of contrast, and placement of balloon markers in the region of interest. RESULTS The cases presented significantly facilitated the identification of bifurcation stenting techniques, precise stent positioning, stent underexpansion and assisted with defining stent-vessel wall relationship that was additive to intravascular ultrasound. CONCLUSIONS ESV is a novel tool used in coronary interventions that facilitates non-invasive assessment of stent positioning, expansion and stent-vessel interactions. This inexpensive ESV technique is complimentary to IVUS and in some cases obviates its need.