Computational hemodynamic analysis in congenital heart disease: simulation of the Norwood procedure.

Hypoplastic left heart syndrome (HLHS) is a congenital heart disease which should be treated at neonate. Even now, its operation is one of the greatest challenges. However, currently there are no quantitative standards to evaluate and predict the outcome of the therapy. In this study, computational fluid dynamics (CFD) was used to estimate the performance of first stage HLHS surgery, the Norwood operation. An image data transfer system was developed to convert clinical images into three-dimensional geometry. To confirm software applicability, a validation process was carried out to eliminate any influence of numerical procedures. The velocities derived from echocardiography measurements were used as boundary conditions, and pressure waves measured by a cardiac catheter simultaneous with an electrocardiogram (ECG) were employed to validate the results of CFD simulation. Calculated results were congruent with the in vivo measurement results. The blood flow circulations were successfully simulated and the distribution of blood flow in each vessel was estimated. Time-varying energy losses (EL), local pressure and wall shear stress (WSS) were analyzed to estimate clinical treatment. The results indicated that pulsatile simulation is essential in quantitative evaluation. Computational hemodynamics may be applied in the surgical optimization for the treatment of HLHS.

Development of porous ceramics with well-controlled porosities and pore sizes from apatite fibers and their evaluations.

Porous hydroxyapatite (HAp) ceramics possessing well-controlled porosities and pore sizes were developed by firing apatite-fiber compacts mixed with carbon beads and agar. The total porosities could be controlled in the range from 40 to 85% by varying compaction pressure (20-40 MPa), firing temperature (1000-1300 degrees C) and carbon/HAp ratio (0/10-10/10 (w/w)). Most of the pores were regarded as open pores. The pore sizes were mainly affected by the carbon-bead diameter (5, 20 or 150 microm) and partly by the compaction pressure and the firing temperature. The pore sizes of the porous HAp ceramics derived from the carbon beads of 150 microm in diameter were distributed in the two separate ranges of several micrometers and more than 100 microm.

[Arteriovenous malformation associated with cyst. Case report].

The authors present the fifth reported case of arteriovenous malformation (AVM) associated with cyst formation. Among these five cases, computed tomography has demonstrated two types of cyst: round, and slit-like with low density. The three patients with slit-like cysts experienced sudden, severe headache, probably due to hemorrhage. The two patients with round cystic lesions did not have sudden headache, and at surgery the cysts were found to contain a mural nodule. These facts suggest that there may be two different mechanisms of cyst formation in the vicinity of an AVM: hemorrhage (slit-like cysts) and exudation (round cysts).

Cystic arteriovenous malformation. A case report.

The authors report on a rare case of arteriovenous malformation (AVM) associated with cyst formation. Only five similar cases have been reported. CT findings of the cyst are divided into two types: 1) slit-like low density and 2) round one. Three patients showing slit-like cysts had experienced sudden severe headaches, probably due to haemorrhage. In contrast, two patients showing round cystic lesions had not experienced such sudden headaches and they revealed a nodule in the cyst at surgery. These facts suggest that there may be two different mechanisms for cyst formation in AVM's: haemorrhage and exudation. Slit-like cysts may result from old haemorrhage from the AVM nidus. Round cystic lesions may be due to exudation from the AVM nidus.

Stereotactic operation for brain abscess.

Stereotactic management of brain abscess (stereotactic aspiration with external drainage) was performed in 14 patients. Fifteen abscesses in 14 patients were successfully aspirated by this method. After aspiration of the abscess, all patients underwent external drainage for an average of 14.5 days. No complications during aspiration or during external drainage (such as bleeding or infection, respectively) were encountered in our series. Ten out of 14 patients (71.4%) showed excellent prognosis, and 3 of 14 (21.4%) showed good outcome. Only one patient died after the operation, but this was due to lung cancer. Our operative results are quite satisfactory in comparison with operative results reported by other authors.