Creation of ventricular septal defects on the beating heart in a new pig model

Background/ Aims: So far, surgical and interventional therapies for muscular ventricular septal defects ( mVSDs) beyond the moderator band have had their limitations. Thus, alternative therapeutic strategies should be developed. We present a new animal model for the evaluation of such strategies. Methods: In a pig model ( n = 9), anterolateral thoracotomy was performed for exposure of the left ventricle. mVSDs were created under two- and three- dimensional echocardiography with a 7.5- mm sharp punch instrument, which was forwarded via a left ventricular puncture without extracorporeal circulation. Results: Creation of mVSDs was successful in all animals ( n = 9) confirmed by echocardiography, hemodynamic measurements and autopsy. The defects were located in the midmuscular ( n = 4), apical ( n = 1), inlet ( n = 2) and anterior part ( n = 2) of the muscular septum. All animals were hemodynamically stable for further procedures. The diameter and shunt volume of the mVSDs were 4.8 - 7.3 mm ( mean: 5.9 mm) and 12.9 - 41.3% ( mean: 22.1%), respectively. Autopsy confirmed in all animals the creation of a substantial defect. Conclusion: The described new technique for creation of an mVSD on the beating heart in a pig model is suitable for the evaluation of new therapeutic strategies for mVSD closure. Copyright (C) 2008 S. Karger AG, Basel

Design and Fabrication of Three-Dimensional Scaffolds for Tissue Engineering of Human Heart Valves

We developed a new fabrication technique for 3-dimensional scaffolds for tissue engineering of human heart valve tissue. A human aortic homograft was scanned with an X-ray computer tomograph. The data derived from the X-ray computed tomogram were processed by a computer-aided design program to reconstruct a human heart valve 3-dimensionally. Based on this stereolithographic model, a silicone valve model resembling a human aortic valve was generated. By taking advantage of the thermoplastic properties of polyglycolic acid as scaffold material, we molded a 3-dimensional scaffold for tissue engineering of human heart valves. The valve scaffold showed a deviation of only +/- 3-4% in height, length and inner diameter compared with the homograft. The newly developed technique allows fabricating custom-made, patient-specific polymeric cardiovascular scaffolds for tissue engineering without requiring any suture materials. Copyright (c) 2008 S. Karger AG, Base

Conservative treatment of a left atrial intramural hematoma after left atrial thrombus resection and concomitant mitral valve replacement - case report

Left atrial intramural hematoma is a seldom cause of left atrial mass. It has been described to occur spontaneously, after interventional procedures, after blunt chest trauma, or after aortocoronary bypass surgery. We present a case of mitral valve replacement together with the removal of a large intraatrial space-occupying lesion. Intraoperative transesophageal echocardiography confirmed a successful resection of this mass. Surprisingly, upon admission to ICU, transesophageal and transthoracic echocardiography revealed a recurrence of an intramural lesion, closest matching a hematoma, which was confirmed by contrast-enhanced computed tomography. Surgical intervention was thoroughly discussed but a conservative management was favoured. 3 months after surgery, a reassessed transthoracic echocardiography and computed tomography demonstrated an almost complete resolution of the pre-existing hematoma

The Search for Invariance: Repeated Positive Testing Serves the Goals of Causal Learning

Positive testing is characteristic of exploratory behavior, yet it seems to be at odds with the aim of information seeking. After all, repeated demonstrations of one’s current hypothesis often produce the same evidence and fail to distinguish it from potential alternatives. Research on the development of scientific reasoning and adult rule learning have both documented and attempted to explain this behavior. The current chapter reviews this prior work and introduces a novel theoretical account—the Search for Invariance (SI) hypothesis—which suggests that producing multiple positive examples serves the goals of causal learning. This hypothesis draws on the interventionist framework of causal reasoning, which suggests that causal learners are concerned with the invariance of candidate hypotheses. In a probabilistic and interdependent causal world, our primary goal is to determine whether, and in what contexts, our causal hypotheses provide accurate foundations for inference and intervention—not to disconfirm their alternatives. By recognizing the central role of invariance in causal learning, the phenomenon of positive testing may be reinterpreted as a rational information-seeking strategy

Is It Rational to Assume that Infants Imitate Rationally? A Theoretical Analysis and Critique

It has been suggested that preverbal infants evaluate the efficiency of others' actions (by applying a principle of rational action) and that they imitate others' actions rationally. The present contribution presents a conceptual analysis of the claim that preverbal infants imitate rationally. It shows that this ability rests on at least three assumptions: that infants are able to perceive others' action capabilities, that infants reason about and conceptually represent their own bodies, and that infants are able to think counterfactually. It is argued that none of these three abilities is in place during infancy. Furthermore, it is shown that the idea of a principle of rational action suffers from two fallacies. As a consequence, is it suggested that it is not rational to assume that infants imitate rationally. Copyright (C) 2012 S. Karger AG, Base

Entwicklung und Ungleichheit von Fähigkeiten : Anmerkungen aus ökonomischer Sicht

Nirgends sonst im ökonomischen Handeln fallen Kosten und Nutzen im Zeitablauf und aufgeteilt nach Investoren und Nutznießern so eklatant auseinander wie bei Bildungsinvestitionen. In dem vorliegenden Beitrag wird argumentiert, dass in der sozialen Realität die Bildungsungleichheit im Vorschulalter eine der wichtigsten Ursachen für die Ungleichheit von Fähigkeiten und Kompetenzen auch im Schulalter und im Erwerbsleben ist. Für benachteiligte Kinder scheint somit die Bildungsungleichheit vor dem Schulalter bei uns, ebenso wie in anderen Ländern mit hohen Bildungsausgaben und hoher Wirtschaftskraft ihren schicksalhaften Charakter noch keineswegs verloren zu haben. Um dies zu ändern, bleibt es eine vordringliche Aufgabe auch der Bildungspolitik, den Zugang zu einer angemessenen emotionalen Fürsorge von Anfang an weiter zu verbessern. Darüber hinaus ist es notwendig, den betroffenen Kindern bis ins Jugendalter altersgemäß und individuell zur Seite zu stehen

Clinical value of patient-specific three-dimensional printing of congenital heart disease: Quantitative and qualitative assessments

Objective: Current diagnostic assessment tools remain suboptimal in demonstrating complex morphology of congenital heart disease (CHD). This limitation has posed several challenges in preoperative planning, communication in medical practice, and medical education. This study aims to investigate the dimensional accuracy and the clinical value of 3D printed model of CHD in the above three areas. Methods: Using cardiac computed tomography angiography (CCTA) data, a patient-specific 3D model of a 20-month-old boy with double outlet right ventricle was printed in Tango Plus material. Pearson correlation coefficient was used to evaluate correlation of the quantitative measurements taken at analogous anatomical locations between the CCTA images pre- and post-3D printing. Qualitative analysis was conducted by distributing surveys to six health professionals (two radiologists, two cardiologists and two cardiac surgeons) and three medical academics to assess the clinical value of the 3D printed model in these three areas. Results: Excellent correlation (r = 0.99) was noted in the measurements between CCTA and 3D printed model, with a mean difference of 0.23 mm. Four out of six health professionals found the model to be useful in facilitating preoperative planning, while all of them thought that the model would be invaluable in enhancing patient-doctor communication. All three medical academics found the model to be helpful in teaching, and thought that the students will be able to learn the pathology quicker with better understanding. Conclusion: The complex cardiac anatomy can be accurately replicated in flexible material using 3D printing technology. 3D printed heart models could serve as an excellent tool in facilitating preoperative planning, communication in medical practice, and medical education, although further studies with inclusion of more clinical cases are needed

Rationality as a Goal of Education

Abstract Those who believe education should involve more than learning facts often stress either (a) development or (b) thinking skills. A focus on development as a goal of education typically entails a conception of knowledge as organismic, holistic, and internally generated. In contrast, thinking skills programs commonly assume a mechanistic, reductionist perspective in which good thinking consists of some finite number of directly teachable skills. A conception of rationality as a goal of education is proposed that incorporates the complementary strengths and avoids the limitations of the developmental and thinking skills approaches. Rationality is defined as the self-reflective, intentional, and appropriate coordination and use of genuine reasons in generating and justifying beliefs and behavior. Philosophically, rationality is a justifiable goal of education, not only because it is a means to worthwhile ends but because it is an important end in itself and because it can be promoted via non-indoctrinative means. A psychological account of progressive rationality is provided that postulates continuing multiple interactions of (a) domain-specific developmental stages, (b) the learning of specific thinking skills, and (c) content-specific knowledge. Suggestions are made for fostering rationality at various educational levels. Finally, it is argued that the proposed conception of rationality as a goal of education complements and clarifies a variety of other educational goals

Heart Valve Tissue Engineering: Concepts, Approaches, Progress, and Challenges

Potential applications of tissue engineering in regenerative medicine range from structural tissues to organs with complex function. This review focuses on the engineering of heart valve tissue, a goal which involves a unique combination of biological, engineering, and technological hurdles. We emphasize basic concepts, approaches and methods, progress made, and remaining challenges. To provide a framework for understanding the enabling scientific principles, we first examine the elements and features of normal heart valve functional structure, biomechanics, development, maturation, remodeling, and response to injury. Following a discussion of the fundamental principles of tissue engineering applicable to heart valves, we examine three approaches to achieving the goal of an engineered tissue heart valve: (1) cell seeding of biodegradable synthetic scaffolds, (2) cell seeding of processed tissue scaffolds, and (3) in-vivo repopulation by circulating endogenous cells of implanted substrates without prior in-vitro cell seeding. Lastly, we analyze challenges to the field and suggest future directions for both preclinical and translational (clinical) studies that will be needed to address key regulatory issues for safety and efficacy of the application of tissue engineering and regenerative approaches to heart valves. Although modest progress has been made toward the goal of a clinically useful tissue engineered heart valve, further success and ultimate human benefit will be dependent upon advances in biodegradable polymers and other scaffolds, cellular manipulation, strategies for rebuilding the extracellular matrix, and techniques to characterize and potentially non-invasively assess the speed and quality of tissue healing and remodeling