Effect of Fibrin Glue on the Biomechanical Properties of Human Descemet's Membrane

10.1371/journal.pone.0037456PLoS ONE75

Pulmonary and caval flow dynamics after total cavopulmonary connection

Objective—To assess flow dynamics after total cavopulmonary connection (TCPC).
Design—Cross-sectional study.
Setting—Aarhus University Hospital. 
Patients—Seven patients (mean age 9 (4-18) years) who had previously undergone a lateral tunnel TCPC mean 2 (0.3-5) years earlier. 
Interventions—Pressure recordings (cardiac catheterisation), flow volume, and temporal changes of flow in the lateral tunnel, superior vena cava, and right and left pulmonary arteries (magnetic resonance velocity mapping).
Results—Superior vena cava flow was similar to lateral tunnel flow (1.7 (0.6-1.9) v 1.3 (0.9-2.4) l/min*m(2)) (NS), and right pulmonary artery flow was higher than left pulmonary artery flow (1.7 (0.6-4.3) v 1.1 (0.8-2.5) l/min*m(2), p < 0.05). The flow pulsatility index was highest in the lateral tunnel (2.0 (1.1-8.5)), lowest in the superior vena cava (0.8( )(0.5-2.4)), and intermediate in the left and right pulmonary arteries (1.6 (0.9-2.0) and 1.2 (0.4-1.9), respectively). Flow and pressure waveforms were biphasic with maxima in atrial systole and late ventricular systole.
Conclusions—Following a standard lateral tunnel TCPC, flow returning via the superior vena cava is not lower than flow returning via the inferior vena cava as otherwise seen in healthy subjects; flow distribution to the pulmonary arteries is optimal; and some pulsatility is preserved primarily in the lateral tunnel and the corresponding pulmonary artery. This study provides in vivo data for future in vitro and computer model studies.

 Keywords: blood flow dynamics;  total cavopulmonary connection;  congenital heart diseas

Increased platelet reactivity and significant changes in coagulation markers after cavopulmonary connection

OBJECTIVE—To evaluate platelet reactivity and coagulation markers after surgical palliation of univentricular hearts.
DESIGN AND PATIENTS—Cross sectional survey of 24 patients, median age 11 (range 4-22) years, at 2 (range 0.5-6) years after a total cavopulmonary connection (TCPC; n = 14) or a bidirectional Glenn anastomosis (Glenn; n = 10).
MAIN OUTCOME MEASURES—Platelet reactivity and/or coagulation markers were measured in 20 patients (four excluded because of anticoagulant treatment) and compared with 33 healthy controls, median age 12 (range 6-16) years.
RESULTS—None of the patients had clinically apparent thromboembolic events. However, increased platelet reactivity was observed ex vivo both after collagen induced platelet aggregation (median 73% (interquartile range 61-84%) in patients, and 61% (47-69%) in controls; p < 0.01), and after ADP induced platelet aggregation (69% (53-77%) in patients, and 56% (40-66%) in controls; p < 0.05). Concentrations of protein S antigen, antithrombin III, and protein C activity were reduced after both TCPC and Glenn. A concomitant decrease was seen in coagulation factor II, VII, X, and factor VII clot activity.
CONCLUSIONS—Several abnormalities in the coagulation system were observed after bidirectional Glenn anastomosis, similar to alterations previously described in Fontan operated and TCPC patients. Antithrombotic treatment in these patients is still an unresolved issue, but aspirin is often recommended. This study shows that such a strategy is rational and the results suggest that antiplatelet treatment may be advantageous, either alone or in combination with oral anticoagulant treatment.


Keywords: Fontan procedure; thrombosis; platelets; coagulatio

Application of structural analysis to the mechanical behaviour of the cornea.

Structural engineering analysis tools have been used to improve the understanding of the biomechanical behaviour of the cornea. The research is a multi-disciplinary collaboration between structural engineers, mathematical and numerical analysts, ophthalmologists and clinicians. Mathematical shell analysis and nonlinear finite-element modelling have been used in conjunction with laboratory experiments to study the behaviour of the cornea under different loading states and to provide improved predictions of the mechanical response to disease and injury. The initial study involved laboratory tests and mathematical back analysis to determine the corneal material properties and topography. These data were then used to facilitate the construction of accurate finite-element models that are able to reliably trace the performance of cornea upon exposure to disease, injury or elevated intra-ocular pressure. The models are being adapted to study the response to keratoconus (a disease causing loss of corneal tissue) and to tonometry procedures, which are used to measure the intra-ocular pressure. This paper introduces these efforts as examples of the application of structural engineering analysis tools and shows their potential in the field of corneal biomechanics