Michael S. Kim

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.

Percutaneous Transcatheter Closure of Prosthetic Mitral Paravalvular Leaks : Are We There Yet?

A potential complication of mitral valve replacement surgery is the development of a paravalvular leak (PVL). Percutaneous transcatheter closures of PVLs using a wide array of devices have been reported in the literature, although the procedural success rate of this approach remains variable. One major challenge of transcatheter mitral PVL closure lies in the ability to adequately visualize the area of interest to facilitate defect crossing and equipment selection. Furthermore, the current spectrum of devices available for off-label use in the closure of these unique defects remains limited. This review examines the current state of transcatheter prosthetic mitral PVL closure, describes our institutions experience using advanced imaging modalities for procedural guidance, and illustrates some of the limitations associated with using existing devices in transcatheter PVL closure.

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.

Clinical Feasibility of a Fully Automated 3D Reconstruction of Rotational Coronary X-Ray Angiograms

Background—Although fixed view x-ray angiography remains the primary technique for anatomic imaging of coronary artery disease, the known shortcomings of 2D projection imaging may limit accurate 3D vessel and lesion definition and characterization. A recently developed method to create 3D images of the coronary arteries uses x-ray projection images acquired during a 180° C-arm rotation and continuous contrast injection followed by ECG-gated iterative reconstruction. This method shows promise for providing high-quality 3D reconstructions of the coronary arteries with no user interaction but requires clinical evaluation. Methods and Results—The reconstruction strategy was evaluated by comparing the reconstructed 3D volumetric images with the 2D angiographic projection images from the same 23 patients to ascertain overall image quality, lesion visibility, and a comparison of 3D quantitative coronary analysis with 2D quantitative coronary analysis. The majority of the resulting 3D volume images were rated as having high image quality (66%) and provided the physician with additional clinical information such as complete visualization of bifurcations and unobtainable views of the coronary tree. True-positive lesion detection rates were high (90 to 100%), whereas false-positive detection rates were low (0 to 8.1%). Finally, 3D quantitative coronary analysis showed significant similarity with 2D quantitative coronary analysis in terms of lumen diameters and provided vessel segment length free from the errors of foreshortening. Conclusions—Fully automated reconstruction of rotational coronary x-ray angiograms is feasible, produces 3D volumetric images that overcome some of the limitations of standard 2D angiography, and is ready for further implementation and study in the clinical environment.

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.

Association of prior coronary artery bypass graft surgery with quality of care of patients with non-ST-segment elevation myocardial infarction: a report from the National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With the Guidelines.

BACKGROUND The American College of Cardiology/American Health Association guidelines recommend both an early invasive strategy and administration of antiplatelet/anticoagulant therapy for high-risk patients in the absence of contraindications. Little is known about adherence to guideline recommendations in patients with prior coronary artery bypass graft (CABG) surgery presenting with non-ST-segment elevation myocardial infarction (NSTEMI). METHODS We analyzed 47,557 patients with NSTEMI in the 2007-2008 National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With The Guidelines. Treatment patterns were compared between patients with and without prior CABG surgery. Multivariable regression with generalized estimating equations evaluated the association between prior CABG and in-hospital outcomes. RESULTS In this study, 8,790 NSTEMI patients (18.5%) had a history of CABG surgery. Prior CABG surgery was associated with a significantly lower adjusted likelihood of early cardiac catheterization (adjusted odds ratio [OR] 0.88, 95% CI 0.83-0.92), higher rates of short-term clopidogrel use (adjusted OR 1.08, 95% CI 1.02-1.14), and comparable use of anticoagulant therapy (adjusted OR 0.96, 95% CI 0.88-1.04). Adjusted risks of bleeding and in-hospital mortality did not differ significantly between the 2 groups (adjusted ORs 1.00, 95% CI 0.92-1.11 and 0.99, 95% CI 0.87-1.11, respectively). CONCLUSIONS Patients with prior CABG surgery presenting with NSTEMI are often felt to be at high risk for adverse outcomes and therefore require aggressive treatment. Our study indicates that they are less likely to undergo guideline-recommended early cardiac catheterization but equally or more likely to receive guideline-recommended antiplatelet and anticoagulant therapy. This risk-treatment paradox, however, does not appear to negatively influence short-term clinical outcomes.

The missing leak: a case report of a baffle-leak closure using real-time 3D transoesophageal guidance

Brady-arrhythmias in patients undergone atrial switch procedures (Mustard or Senning procedure) for complete transposition of the great arteries (TGA) are common and often require implantation of permanent pacemakers. It has been shown that in patients with palliated congenital cardiac defects with residual intra-cardiac shunts, permanent pacemaker implantation is associated with an increased risk of thrombo-embolism. Patients with TGA and concomitant baffle leaks may have an even further increased thrombo-embolic risk, given that the leaks can provide the conduit for venous to systemic thrombo-embolism. In order to decrease this risk, all TGA patients who require pacemaker implantation typically undergo a thorough pre-procedural evaluation to assess for the presence of a baffle leak. Traditional imaging modalities, however, are often limited in their ability to detect and/or properly locate small baffle leaks. We report a case of a patient with TGA and a baffle leak that was both identified and percutaneously closed with the assistance of real-time 3D transoesophageal echocardiography.

Left ventricular outflow tract obstruction in the presence of asymmetric septal hypertrophy and accessory mitral valve tissue treated with alcohol septal ablation.

Redundant or accessory mitral valve tissue (AMVT) is a rare clinical condition. It is an even rarer cause of left ventricular outflow tract obstruction. We report a case of an adult male with medically unresponsive hypertrophic obstructive cardiomyopathy in whom real-time three-dimensional transesophageal echocardiography was used to both diagnose the presence of coexistent asymmetric septal hypertrophy and AMVT as well as confirm the safety and efficacy of treatment with alcohol septal ablation.

Coronary Stent Fracture : Clinical Use of Image Enhancement

Standard angiography and intravascular ultrasound (IVUS) have limited ability to visualize stent struts and their integrity over time. While it is thought that stent fracture is associated with high incidence of restenosis or thrombosis, the true incidence of stent fracture is difficult to ascertain

Integrated 3D Echo-X-Ray Navigation to Predict Optimal Angiographic Deployment Projections for TAVR

Transcatheter aortic valve replacement (TAVR) is an established and accepted therapeutic option for both inoperable and high-risk surgical patients with severe aortic stenosis. Precise prosthetic valve positioning in the 3-dimensional (3D) aortic annulus is a critical component of a successful TAVR