4D modelling for rapid assessment of biventricular function in congenital heart disease.

Although more patients with congenital heart disease (CHD) are now living longer due to better surgical interventions, they require regular imaging to monitor cardiac performance. There is a need for robust clinical tools which can accurately assess cardiac function of both the left and right ventricles in these patients. We have developed methods to rapidly quantify 4D (3D + time) biventricular function from standard cardiac MRI examinations. A finite element model was interactively customized to patient images using guide-point modelling. Computational efficiency and ability to model large deformations was improved by predicting cardiac motion for the left ventricle and epicardium with a polar model. In addition, large deformations through the cycle were more accurately modeled using a Cartesian deformation penalty term. The model was fitted to user-defined guide points and image feature tracking displacements throughout the cardiac cycle. We tested the methods in 60 cases comprising a variety of congenital heart diseases and showed good correlation with the gold standard manual analysis, with acceptable inter-observer error. The algorithm was considerably faster than standard analysis and shows promise as a clinical tool for patients with CHD.

An interactive tool for rapid biventricular analysis of congenital heart disease.

Cardiac malformations are the most common birth defect. Better interventions in early life have improved mortality for children with congenital heart disease, but heart failure is a significant problem in adulthood. These patients require regular imaging and analysis of biventricular (left and right ventricular) function. In this study, we describe a rapid method to analyse left and right ventricular shape and function from cardiac MRI examinations. A 4D (3D+time) finite element model template is interactively customized to the anatomy and motion of the biventricular unit. The method was validated in 17 patients and 10 ex-vivo hearts. Interactive model updates were achieved through preconditioned conjugate gradient optimization on a multithread system, and by precomputing points predicted from a coarse mesh optimization.

A copper(II)-selective chelator ameliorates left-ventricular hypertrophy in type 2 diabetic patients: a randomised placebo-controlled study.

AIMS/HYPOTHESIS: Cu(II)-selective chelation with trientine ameliorates cardiovascular and renal disease in a model of diabetes in rats. Here, we tested the hypothesis that Cu(II)-selective chelation might improve left ventricular hypertrophy (LVH) in type 2 diabetic patients. METHODS: We performed a 12 month randomised placebo-controlled study of the effects of treatment with the Cu(II)-selective chelator trientine (triethylenetetramine dihydrochloride, 600 mg given orally twice daily) on LVH in diabetic patients (n = 15/group at baseline) in an outpatient setting wherein participants, caregivers and those assessing outcomes were blinded to group assignment. Using MRI, we measured left ventricular variables at baseline, and at months 6 and 12. The change from baseline in left ventricular mass indexed to body surface area (LVM(bsa)) was the primary endpoint variable. RESULTS: Diabetic patients had LVH with preserved ejection fraction at baseline. Trientine treatment decreased LVM(bsa) by 5.0 +/- 7.2 g/m(2) (mean +/- SD) at month 6 (when 14 trientine-treated and 14 placebo-treated participants were analysed; p = 0.0056 compared with placebo) and by 10.6 +/- 7.6 g/m(2) at month 12 (when nine trientine-treated and 13 placebo-treated participants were analysed; p = 0.0088), whereas LVM(bsa) was unchanged by placebo treatment. In a multiple-regression model that explained ~75% of variation (R (2) = 0.748, p = 0.001), cumulative urinary Cu excretion over 12 months was positively associated with trientine-evoked decreases in LVM(bsa). CONCLUSIONS/INTERPRETATION: Cu(II)-selective chelation merits further exploration as a potential pharmacotherapy for diabetic heart disease. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN 12609000053224 FUNDING: The Endocore Research Trust; Lottery Health New Zealand; the Maurice and Phyllis Paykel Trust; the Foundation of Research, Science and Technology (New Zealand); the Health Research Council of New Zealand; the Ministry of Education (New Zealand) through the Maurice Wilkins Centre for Molecular Biodiscovery; and the Protemix Corporation.

Occlusion of a giant saphenous vein graft aneurysm using distal coil embolisation and a proximal vascular plug.

An asymptomatic giant true saphenous vein graft aneurysm was successfully occluded by percutaneous distal coil embolisation combined with deployment of a proximal Amplatzer vascular occlusion plug. The aneurysm cavity was excluded from both antegrade flow via the aortosaphenous anastamosis and retrograde flow via the distal left anterior descending coronary artery (supplied by a left internal mammary artery graft), to reduce the risk of subsequent aneurysm rupture.

Wall shear stress is the primary mechanism of energy loss in the Fontan connection.

Long-term outcome following the Fontan operation may be affected by the amount of energy lost as blood flows through the anastomosis geometry. A method for detailed quantification of energy loss is applied to computational simulations of the flow in an atriopulmonary and a total cavopulmonary model. Five types of flow (near wall, slow recirculation, medium speed vortices, collision, and streamlined flow) are identified and their energy losses quantified. The presence of recirculation regions decreases the efficiency of the atriopulmonary model, and a region of increased energy loss is seen in the collision region in the total cavopulmonary model. However, the most significant energy loss is through wall shear stress, which is maximal in areas where there is rapid, near wall flow.

Subclinical aortic perforation with the infant double-button patent ductus arteriosus occluder.

Modification of the double-button (Sideris) patent ductus arteriosus (PDA) occluder has resulted in a single-strut aortic component rather than the conventional cross-strut design. We report the use of this infant PDA occluder for transcatheter closure in three patients with PDA measuring 2 mm, 3.7 mm, and 4 mm. Subclinical aortic perforation with a small aortic aneurysm developed in two patients 1 year after occluder implantation. The third patient had developed a small aortic aneurysm without perforation at 3-month follow-up. All three patients had a residual shunt and underwent successful PDA surgical closure with aortic aneurysmal repair. Single-strut umbrella designs are not recommended for PDA transcatheter closure.

Depth of central venous catheterization: an audit of practice in a cardiac surgical unit.

Central venous catheter (CVC) depth relative to the cephalic limit of the pericardial reflection (CLPR) was assessed retrospectively in 100 adult patients from chest radiographs taken after admission to the intensive care unit. A well known landmark proved to be considerably influenced by parallax; therefore we located the CLPR by a new landmark, the junction of the azygos vein and the superior vena cava, identified by the angle of the right main bronchus and the trachea. The majority (58) of CVC tips lay below the pericardial reflection on the first chest radiograph (CXR). Of these only two had been corrected by the time of the next routine CXR. No case of cardiac tamponade secondary to erosion by a CVC could be remembered, or identified from records of routine departmental audit meetings, for the last ten years. Nevertheless, reported incidents of this complication have often been fatal and vigilance is necessary in any patient with a CVC.

Can a calcaneal morphologic index determine the degree of osteoporosis?

The proposal that a scoring system of the radiographic trabecular patterns of the os calcis could be related to degree of osteoporosis was tested. The technique fails as it showed no correlation with actual bone density determined by a Compton scatter technique and because of a low level of observer concordance. Possible reasons for the poor performance of the index developed in India when applied to North Americans are discussed.