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BACKGROUND: Left ventricular myocytes are arranged in a complex three-dimensional mesh. Since all myocytes contract approximately to the same degree, mechanisms must exist to enable force transfer from each of these onto the framework as a whole, despite the transmural differences in deformation strain. This process has hitherto not been clarified in detail. OBJECTIVE: To present a geometrical model that establishes a mechanical link between the three-dimensional architecture and the function of the left ventricular myocardium. METHODS: The left ventricular equator was modeled as a cylindrical tube of deformable but incompressible material, composed of virtual cardiomyocytes with known diastolic helical and transmural angles. By imposing reference circumferential, longitudinal, and torsional strains onto the model, we created a three-dimensional deformation field to calculate passive shortening of the myocyte surrogates. We tested two diastolic architectures: 1) a simple model with longitudinal myocyte surrogates in the endo- and epicardium, and circular ones in the midwall, and 2) a more accurate architecture, with progressive helical angle distribution varying from -60° in the epicardium to 60° in the endocardium, with or without torsion and transmural cardiomyocyte angulation. RESULTS: The simple model caused great transmural unevenness in cardiomyocyte shortening; longitudinal surrogates shortened by 15% at all depths equal to the imposed longitudinal strain, whereas circular surrogates exhibited a maximum shortening of 23.0%. The accurate model exhibited a smooth transmural distribution of cardiomyocyte shortening, with a mean (range) of 17.0 (13.2-20.8)%. Torsion caused a shortening of 17.0 (15.2-18.9)% and transmural angulation caused a shortening of 15.2 (12.4-18.2)%. Combining the effects of transmural angulation and torsion caused a change of 15.2 (13.2-16.5)%. CONCLUSION: A continuous transmural distribution of the helical angle is obligatory for smooth shortening of the cardiomyocytes, but a combination of torsional and transmural angulation changes is necessary to execute systolic mural thickening whilst keeping shortening of the cardiomyocytes within its physiological range. [ABSTRACT FROM AUTHOR]

The components that define cereal-grain yield potential have not been well defined. The objective of this study was to collect many differing biological measurements from a long-term winter wheat ( Triticum aestivum L.) study in an attempt to better define yield potential. Four treatments were sampled that annually received 0, 45, 90, and 135 kg N ha -1 at fixed rates of phosphorus (P) (30 kg ha -1 ) and potassium (K) (37 kg ha -1 ). Mid-season measurements of leaf color, chlorophyll, normalized difference vegetative index (NDVI), plant height, canopy temperature, tiller density, plant density, soil moisture, soil NH 4 -N, NO 3 -N, organic carbon (C), total nitrogen (N), pH, and N mineralization potential were collected. In addition, soil texture and bulk density were determined to characterize each plot. Correlations and multiple linear-regression analyses were used to determine those variables that can predict final winter wheat grain yield. Both the correlation and regression analyses suggested mid-season NDVI, chlorophyll content, plant height, and total N uptake to be good predictors of final winter wheat grain yield. [ABSTRACT FROM AUTHOR]

Fermi-liquid theory is adapted to describe the effective interactions of ³He adsorbed to a thin superfiuid 4He film in an external magnetic field. We treat the SHe as a two-dimensional Fermi-liquid with both direct interactions and indirect interactions mediated by the film excitations, the ripplons. The Landau f-functions are state and field dependent. In this manuscript, we report on a calculation of the SHe magnetization as a function of coverage. We show that the magnetization is given as an integral over the magnetic field strength with the integrand expressed in terms of the Landau interaction functions fkf↑,kf↑; fkf↑,kf↓;; fkf↓,kf↓ for clarity, we have suppressed the transverse state indices). A few concluding comments are made about the contributions to the Landau f-functions from the direct and from the surface mediated indirect interactions as compared with the bulk situation. [ABSTRACT FROM AUTHOR]

Investigates the detailed anatomy of the terminal crest and its junctional regions with the pectinate muscles and intercaval area to provide the yardstick for structural normality. Normal anatomy of the muscle fibers and connective tissue in the junctional area of the terminal crest/pectinate muscles and terminal crest/intercaval bundle; Scanning electron microscopy and histology; Implications on cardiology.

Aims Our aim was to clarify the location and structure of the outlet septum relative to the free-standing sub-pulmonary infundibulum in the setting of tetralogy of Fallot and to examine its relationship to the other components of the subpulmonary outflow tract, determining their potential influence on clinical outcome. Methods and Results We studied prospectively 41 patients with tetralogy of Fallot (mean age 14±10·9 months) prior to surgical repair, and compared them with 15 patients undergoing closure of a ventricular septal defect associated with malalignment of the outlet septum but no subpulmonary infundibular stenosis (Eisenmenger ventricular septal defect), and 20 healthy controls. We also examined available autopsied hearts from cases with uncorrected tetralogy of Fallot (8) and Eisenmenger ventricular septal defect (13). Data were indexed for body surface area, and diameter of the tricuspid valve, respectively. The overall length of the subpulmonary infundibulum, including the extent of the muscular outlet septum, was significantly greater for patients with tetralogy of Fallot compared to normals (2·34±0·6 vs 1·46±0·34cm/BSA0·5,P<0·001), whereas the difference between those with tetralogy of Fallot and an Eisenmenger ventricular septal defect was confined to the degree of narrowing of the subpulmonary outlet (0·43±0·22 vs 2·17±0·64cm/BSA0·5,P<0·001). Within the tetralogy of Fallot group, there were linear relationships between deviation of the outlet septum (r=−0·61,P<0·005) and the diameter of the pulmonary valvar orifice (r=0·75,P<0·001), suggesting that growth of the pulmonary arteries may be related to this feature. When patients requiring a transannular patch as part of their surgical repair were compared with those not needing this procedure, differences were found in the diameter of the pulmonary valvar orifice and the pulmonary trunk, but not in the dimensions of the outlet septum. Conclusion The position of the outlet septum in relationship to the remainder of the muscular subpulmonary infundibulum represents a hallmark of tetralogy of Fallot, permitting its differentiation from Eisenmenger ventricular septal defects and normal hearts. [ABSTRACT FROM PUBLISHER]

Focuses on the observation of the neonatal electrocardiogram recorded from April 1975 and April 1976 in Great Britain. Verification of the normal variation of the babies; Manifestation of asymptotic conduction abnormalities; Link of the study in conducting tissue abnormalities and the sudden infant death syndrome.

Objectives: To examine morphological similarities between “classically different” congenital heart lesion types induced in fetal rats by the cardiac teratogen N,N′-bis(dichloroacetyl)-1,8-octamethylenediamine (bis-diamine). Methods: A single 200 mg oral dose of bis-diamine was given to 50 pregnant rats on the 9th gestational day. Eleven controls were fed an inert vehicle. Experimental and control rats were sacrificed from 15.4 days to term and embryos delivered by caesarean section. Age-matched embryos were processed for histology and sectioned at 7 μm. Cardiac morphology was compared between normal and bis-diamine exposed groups. Results: Hearts from control embryos were morphologically normal. Those from bis-diamine treated embryos exhibited common arterial trunk (32%), overriding aortic valve with valvar pulmonary stenosis (40%) or infundibular atresia (4%), or ventricular septal defect (24%). Development of the outlet septum was affected in all hearts and the arterial duct was absent in 72% of cases. Whilst most hearts demonstrated the anatomy expected for their lesion, some with a common arterial valve demonstrated a pulmonary blood supply similar to that in human cases of pulmonary atresia, where, in the absence of an arterial duct, an essential systemic to pulmonary conduit was provided by a “persistent fifth aortic arch artery”. In one such case, the proximal part of the aortopulmonary septum was identified above a common valve. The septum was deviated to the left and was not continuous throughout the length of the arterial trunk, causing atresia of the pulmonary component. Others had muscular infundibular atresia but with a pulmonary blood supply arising directly from the solitary trunk as seen in common arterial trunk “type III”. Conclusions: Bis-diamine consistently affects development of those structures which partition the arterial segment of the developing heart at one or more levels, often coexistent with agenesis of the sixth aortic arch arteries. Whilst the aortopulmonary and outlet septums were absent in most cases of common arterial trunk, some morphological duality was shared by classically different lesion types in these rat hearts, which may suggest a common aetiology for common arterial trunk “type III” and aortic overriding with absence of the outlet septum and pulmonary atresia. [ABSTRACT FROM PUBLISHER]

Objectives: To study the development of aortic to mitral fibrous continuity in the normal rat heart. Methods: The hearts and great vessels of normally developed rat embryos and fetuses aged between 13.25 and 19.75 days of gestation were studied in conjunction with those of newborns aged 2 and 7 days post-partum. Standard histological methods and monoclonal antibodies raised against alpha smooth muscle actin (clone 1A4) and ventricular beta myosin heavy chain were used to demonstrate the ventricular outlets, ventriculo-arterial junction, inner heart curve and aortic infundibulum from the early stages of aortopulmonary septation to attainment of their definitive morphology. Results: The two antibodies demonstrated temporal specificity (actin specificity increased post-partum; myosin specificity maximal during fetal period) in the labelling of their intended structures which correlated with their known developmental profile. Full-thickness fibrous continuity between aortic and mitral valves was not complete until 1 week after birth. After ventricular septation was complete, and thereafter towards the end of fetal life and beyond, separation was maintained by a muscular structure histologically identical to the vestigial netro-aortic root branch of the conduction tissue, a structure known to be derived from the primitive ventricular myocardium within the environs of the inner heart curve. Conclusions: Ventricular septation (occurring relatively early) and the attainment of fibrous continuity (occurring relatively late in development) are two independent processes. Muscular tissue separating left-sided arterial and atrioventricular valves is not derived from the aortic infundibulum but from the inner heart curve. Persistence of this structure is a feature of normal rat heart development and needs to be recognised when working with rodent-based animal models of congenital heart disease aimed at studying the disruption of the development of the ventricular outflow tracts. [ABSTRACT FROM PUBLISHER]

Investigates cardiac arrhythmias and other forms of conduction abnormalities in newborn infants through electrocardiography (ECG). Exanimation on 2030 infants through ECG between April 1975 and April 1977; Existence of serious arrhythmias on infants without clinical disturbance; Analysis on the ECG appearance of some arrhythmias.

Presents cases on cardiac conduction disorders in six infants. Characteristic of cardiac conduction disorders; Association of the disorder to sudden death of infants; Illustration of long-term effect of the cardiac conduction disorders; Detection of cardiac conduction disorder through electrocardiograph screening.

Objective: To determine the incidence of postoperative junctional ectopic tachycardia (JET), we reviewed 343 consecutive patients undergoing surgery between 1997 and 1999. The impact of this arrhythmia on inhospital morbidity and our protocol for treatment were assessed. Methods: We reviewed the postoperative course of patients undergoing surgery for ventricular septal defect (VSD; n=161), tetralogy of Fallot (TOF; n=114), atrioventricular septal defect (AVSD; n=58) and common arterial trunk (n=10). All patients with JET received treatment, in a stepwise manner, beginning with surface cooling, continuous intravenous amiodarone, and/or atrial pacing if the haemodynamics proved unstable. A linear regression model assessed the effect of these treatments upon hours of mechanical ventilation, and stay on the cardiac intensive care unit (CICU). Results: Overall mortality was 2.9% (n=10), with three of these patients having JET and TOF. JET occurred in 37 patients (10.8%), most frequently after TOF repair (21.9%), followed by AVSD (10.3%), VSD (3.7%), and with no occurrence after repair of common arterial trunk. Mean ventilation time increased from 83 to 187 h amongst patients without and with JET patients (P<0.0001). Accordingly, CICU stay increased from 107 to 210 h when JET occurred (P<0.0001). Surface cooling was associated with a prolongation of ventilation and CICU stay, by 74 and 81 h, respectively (P<0.02; P<0.02). Amiodarone prolonged ventilation and CICU stay, respectively, by 274 and 275 h (P<0.05; P<0.06). Conclusions: Postoperative JET adds considerably to morbidity after congenital cardiac surgery, and is particularly frequent after TOF repair. Aggressive treatment with cooling and/or amiodarone is mandatory, but correlates with increased mechanical ventilation time and CICU stay. Better understanding of the mechanism underlying JET is required to achieve prevention, faster arrhythmic conversion, and reduction of associated inhospital morbidity. [Copyright &y& Elsevier]