Mirosław Kowalski

Transvenous closure of moderate and large secundum atrial septal defects in adults using the Amplatzer septal occluder

The aim was to determine the feasibility of using the Amplatzer septal occluder for closure of moderate and large secundum atrial septal defects in adults. Fifty patients aged 16–76 years (mean ± SD, 40 ± 15.5), underwent successful device implantation. Flow ratios of 1.4–8.5 (mean ± SD, 2.6 ± 1.6) were calculated. The defects were: centrally placed (n = 31), antero‐superior with partial or total deficiency of aortic rim (n = 19), multiple (n = 3) and with aneurysmal septum (n = 23). They measured 4–25 mm (median 14) on echocardiography and balloon sized 7–31 mm (median 19.5). Devices of 7–34 mm (median 20) were implanted. Patient follow up for 1 month (50/50 patients), 3 months (40/50) and 12 months (13/50), achieved respective rates of 90%, 92% and 98% of complete occlusion. In one patient a transient atrioventricular block (2:1) developed, and one had a transient STT elevation. One female had an episode of 30 min loss of vision over the lateral aspect of the left eye 3 months after implantation. In conclusion, transvenous occlusion of secundum atrial septal defects with the Amplatzer septal occluder in adults is safe, and can be performed without significant complications. Large defects, defects with a very deficient or absent aortic rim, defects with an aneurysmal septum as well as some multiple defects can be closed with an almost 100% early complete occlusion rate. This makes the procedure an alternative to surgery for selected adult patients. Cathet Cardiovasc Intervent 2001;52:188–193.

Clinical and echocardiographic assessment of a right-to-left shunt across an atrial septal defect secondary to tricuspid regurgitation.

Objective — Cyanosis in conjunction with atrial septal defect does not necessarily indicate the Eisenmenger syndrome. Exceptionally, the right-to-left shunt may result from tricuspid regurgitant flow and its unusual direction. Methods — We describe thirteen patients with atrial septal defect and accompanying tricuspid regurgitation. In all of them, the tricuspid regurgitant jet was oriented towards the interatrial septum. This was found on the basis of echocardiographic examination and subsequent frame-by-frame analysis of videotape. Results — Of thirteen patients, cyanosis was observed in 7 (53%). Among those seven, three had moderate pulmonary hypertension (pulmonary artery systolic pressure (PASP) between 40 and 60 mm Hg).The remaining four patients with marked pulmonary hypertension (PASP > 60 mm Hg) underwent cardiac catheterization, which demonstrated low values of pulmonary artery resistance. Except for the one patient with a history of the cerebral embolic event, all were qualified for cardiac surgery. In the postoperative observation they were uneventful and showed clinical recovery and echocardiographic improvement. Conclusions — Appreciable arterial desaturation and cyanosis in patients with ASD, regarded as uncomplicated, should be followed by careful investigation for the direction of tricuspid regurgitant flow.

Left ventricular phantoms with inclusions simulating transmural and non-transmural infarctions: FEM and EchoPAC study

The cardiac elastography evolves to enable local strain estimation and identification of non-transmural infarctions. Below we compare the strain values obtained using EchoPAC in physical left ventricular phantoms made of PVA with results of the Finite Element Modelling (FEM) studies on their counterparts. Models had the form of half of an ellipsoid with 15 mm wall thickness. The homogenous model, transmural inclusion model and nontransmural inclusion (5mm thickness) model were designed. The inclusions were located in the mid segment. The material of the ventricle in the FEM studies was modeled as a hyperelastic, isotropic one. The material parameters came from measurements of the PVA samples for the homogenous case and were extrapolated to obtain stiffer inclusions. The model was deformed by applying 36 kPa pressure load to its inner surface. Peak systolic strain values were close to those observed in healthy subjects. A dedicated setup, the Vivid 6 scanner, probe M4S-RS and EchoPAC BT13 software were used in experiments. The values of strains from FEM models were averaged over nodes corresponding to the layers used in the EchoPAC software. The circumferential strain (CS) values from the FEM simulation and the physical experiment are qualitatively very close and correlate well with the clinical data. The experimental CS results also agree with expectations in terms of slope across the wall and effect of the inclusion. Segmental radial strains obtained from EchoPAC and FEM are close. The proposed approach (phantoms, setup) may be used for development of methods for identification of nontransmural infarctions.

Block matching and B-spline methods in deformation estimation in synthetic left ventricular model with nontransmural infarction

The cardiac elastography aims at identification of non-transmural infarctions. Two displacement estimation methods in such an application using synthetic ultrasonic data are studied. Reference was obtained from Finite Element Modelling. Models had the form of half of an ellipsoid with 15 mm wall thickness. The homogenous model, models with transmural and nontransmural inclusion were designed. Deformation of the models was simulated using Abaqus. Ultrasonic data of LAX and SAX views were generated using Field II. Radial (dR) and lateral (dL) displacements were estimated using a 2D correlation search with 2D stretching (2DCS) and B-spline (BS) method. Strains were estimated using least squares estimator. Mean Absolute Error (MAE) of the dR in the LAX view was approx. 6[μm] for 2DCS and 8[μm] for BS, that of the dL 30 and 24[μm] respectively. MAE of the second component of the principal strain (epsilon)2 was 0.10 and 0.14[%], respectively. Corresponding values for SAX view were 7, 10, 42, 52[μm] and 0.47 and 1.08[%]. In the LAX view both estimation methods result in the (epsilon)2 behavior coherent with the presence of the inclusion, with the 2DCS results closer to the reference. In the SAX view the BS approach results in high errors of the estimate. The (epsilon)2 profiles, LAX view, show minor discrepancies with respect to the reference and show the effect of the inclusion. The (epsilon)2 profiles, SAX view, obtained from displacements estimated using the BS method strongly deviate from the reference. Block matching performs better in application to the local strain estimation.