Research Note: Data systems for occupational injury - the current position

Occupational injuries are a major cause of mortality and morbidity in New Zealand. Despite this, existing national data systems are not easily manipulated to produce occupational injury statistics. No detailed national statistics on occupational injuries have been produced since 1983. There is a need for data on these injuries for research, surveillance, intervention, identification and development, evaluation and planning. This paper highlights the limitations of New Zealand's national data systems for the production of occupational injury statistics

An analysis of the spatial arrangement of the myocardial aggregates making up the wall of the left ventricle

Objective: We used the technique of peeling of myocardial aggregates, usually described as ‘fibres', to determine the spatial arrangement of the myocytes in the left ventricular wall of a healthy autopsied human heart. Methods: We digitised the left ventricular outer and inner boundaries, as well as the pathways in space, of almost 3000 aggregates harvested from the left ventricular myocardium. During the process of gradual peeling, we sought to identify the myocardial aggregates as uniformly as possible. Despite this, interpolation was necessary to complete the pattern so as to construct a unit vector field that represented the preferred direction of the myocardial aggregates throughout the entirety of the walls of the left ventricle of this individual human heart. Results: Apart from the overall systematic arrangement of the aggregates necessary to achieve physiologic ventricular contraction, we documented substantial local heterogeneities in the orientation of the myocardial aggregates. In particular, a significant proportion of aggregates was found to intrude obliquely with respect to the ventricular boundaries, with markedly heterogeneous distribution. Moreover, the distribution of the helical angle of the aggregates relative to the ventricular base varied notably throughout the left ventricular free walls and the septum. Within the generally quite uniform and continuous structure of the ventricular mass, we were, however, unable to identify any organised tracts or functional subunits such as a ‘helical ventricular band', nor did we find radial fibrous lamellas coursing across the ventricular wall. Conclusion: We suggest that the impact of local anatomical inhomogeneities, associated with gradients in regional contractile function on global ventricular dynamics, has been systematically underestimated in the past. Our analysis confirms furthermore the continuous nature of the myocardium associated with an overall gross organisation of the fibre direction field; however, there is no evidence of substructures compartmentalising the ventricle

The myocardium and its fibrous matrix working in concert as a spatially netted mesh: a critical review of the purported tertiary structure of the ventricular mass

With the increasing interest now paid to volume reduction surgery, in which the cardiac surgeon is required to resect the ventricular myocardium to an extent unenvisaged in the previous century, it is imperative that we develop as precise knowledge as is possible of the basic structure of the ventricular myocardial mass and its functional correlates. This is the most important in the light of the adoption by some cardiac surgeons of an unvalidated model which hypothesises that the entire myocardial mass can be unravelled to produce one continuous band. It is our opinion that this model, and the phylogenetic and functional correlates derived from it, is incompatible with current concepts of cardiac structure and cardiodynamics. Furthermore, the proponents of the continuous myocardial band have made no effort to demonstrate perceived deficiencies with current concepts, nor have they performed any histological studies to validate their model. Clinical results using modifications of radius reduction surgery based on the concept of the continuous myocardial band show that the procedure essentially becomes ineffective. As we show in this review, if we understand the situation correctly, it was the erstwhile intention of the promoters of the continuous band to elucidate the basic mechanism of diastolic ventricular dilation. Their attempts, however, are doomed to failure, as is any attempt to conceptualise the myocardial mass on the basis of a tertiary structure, because of the underlying three-dimensional netting of the myocardial aggregates and the supporting fibrous tissue to form the myocardial syncytium. Thus, the ventricular myocardium is arranged in the form of a modified blood vessel rather than a skeletal muscle. If an analogy is required with skeletal muscle, then the ventricular myocardium possesses the freedom of motion, and the ability for shaping and conformational self-controlling that is better seen in the tongue. It is part of this ability that contributes to the rapid end-systolic ventricular dilation. Histologic investigations reveal that the fibrous content of the three-dimensional mesh is relatively inhomogeneous through the ventricular walls, particularly when the myocardium is diseased. The regional capacity to control systolic mural thickening, therefore, varies throughout the walls of the ventricular components. The existence of the spatially netted structure of the ventricular mass, therefore, must invalidate any attempt to conceptualise the ventricular myocardium as a tertiary arrangement of individual myocardial bands or tract

Senior Inquiry: Diversity of the Human Experience

This collaboratively created poster summarizes, in graphic form, the Senior Inquiry students\u27 year-long course of study

Ventricular myocardial architecture as visualised in postmortem swine hearts using magnetic resonance diffusion tensor imaging

Objective: The three-dimensional arrangement of the ventricular myocardial architecture remains controversial, in part because histological assessment is difficult to achieve, while anatomic dissections are, of necessity, destructive. In this study, we describe how the use of magnetic resonance diffusion tensor imaging has permitted us to reconstruct with precision the architecture of the ventricular myocardial fibres in the post-mortem swine heart. Methods and Results: We obtained diffusion-weighted spin-echo measurements of autopsied porcine hearts using a whole body MR system. We calculated the diffusion tensor and the corresponding eigenvectors on a voxel-by-voxel basis. This permitted us to colour code the fibres, and reconstruct them by connecting voxels in direction of the largest eigenvector. Such reconstructions show that, in the middle layer of the left ventricle, most of the fibres have a circular orientation, albit that a far from negligible component runs in a transverse direction. With increasing distance from the epicardium, the orientation of the fibres shows a continuous change in angulation with respect to an axis normal to the epicardium. Conclusion: Our data presented here supports the concept that the ventricular mass is arranged as a complex three-dimensional mesh of tangential and intruding fibres. The data offers no support for the concept of a ‘unique myocardial band'. The method has the potential to detecting deviations from this basic normal architecture, being capable of reconstructing the ventricular mass so as to assess the spatial coordinates of any single fibre strand. The technique, therefore, has major potential clinical applications in the setting of the failing or malformed heart, potentially being able to identify either systematic or regional disarray of the myocardial fibre

Terbutaline and the Prevention of Nocturnal Hypoglycemia in Type 1 Diabetes

OBJECTIVE—Bedtime administration of 5.0 mg of the β2-adrenergic agonist terbutaline prevents nocturnal hypoglycemia but causes morning hyperglycemia in type 1 diabetes. We tested the hypothesis that 2.5 mg terbutaline prevents nocturnal hypoglycemia without causing morning hyperglycemia