Numerical analysis of blood flow distribution in 4- and 3-branch vascular grafts

Trifurcated arch grafts (3-branch grafts) are now being used to repair the thoracic aorta in addition to conventional arch grafts (4-branch grafts). The anatomical shape of the 3-branch graft is different from the original vessel, so it is necessary for clinical application to evaluate blood flow distribution in the graft to assess whether there is adequate blood flow to the target organs. To achieve this, we developed a computational fluid dynamics (CFD) method to evaluate blood flow distribution in the grafts. Aortic blood flow was measured by phase-contrast magnetic resonance imaging (PC-MRI), and flow distribution into the branched vessels was obtained. The MRI image was used to create a patient-specific image model that represents the geometry of the aortic arch. The CFD analysis method was employed to determine a boundary condition of the blood flow analysis in the aorta using a patient-specific image model. We also created simplified models of 4-branch and 3-branch grafts and used our CFD analysis method to compare blood flow distribution among simplified models. It was found that blood flow distribution in the descending aorta was 71.3 % for the 4-branch graft and 67.7 % for the 3-branch graft, indicating that a sum of branching flow in the 3-branch graft was almost the same as the one in the 4-branch graft. Therefore, there is no major concern about implanting a new 3-branch graft. Our CFD analysis method may be applied to estimate blood flow distribution of a newly developed vascular graft prior to its clinical use and provide useful information for safe use of the graft.     

Changes in plasma atrial natriuretic peptide after angiocardiography

BACKGROUND:

Angiocardiography is an important diagnostic modality for evaluation of heart disease. It is well known that the concentration of plasma atrial natriuretic peptide (ANP) increases after injection of contrast medium. On the other hand, some patients with hypertension, heart failure or cardiac hypertrophy have an increased plasma ANP concentration at baseline; however, whether ANP increases after angiography in these patients is unknown.

OBJECTIVES:

To investigate changes in plasma ANP concentrations after angiocardiography in patients with high ANP concentrations at baseline.

PATIENTS AND METHODS:

Plasma ANP concentrations of 32 patients with angina pectoris were measured before and after angiocardiography. They were then classified into two groups according to their ANP concentration before examination.

RESULTS:

ANP concentration after the injection of contrast medium increased significantly in patients with normal ANP concentrations before angiography but did not change in patients with high ANP concentrations at rest.

CONCLUSIONS:

These results suggest that the absence of an increase in ANP after angiography may in part be due to reduced sensitivity to the angiography stimulus or to an already maximal activation of ANP secretion at baseline.     

Involvement of gonadotrophin and steroid hormones in spermiation in the amago salmon, Oncorhynchus rhodurus, and goldfish, Carassius auratus

Effects of intraperitoneal injections of chum salmon gonadotrophin (SGA) and various steroid hormones (17α,20β-dihydroxy-4-pregnen-3-one; 17α,20β-diOHprog, 17α-hydroxy-progesterone, testosterone, 11-ketotestosterone) on the induction of in vivo spermiation were examined in nonspermiating amago salmon (Oncorhynchus rhodurus) and goldfish (Carassius auratus). A single injection of SGA to amago salmon and two successive injections to goldfish induced strong spermiation responses. Similarly two successive injections of 17α, 20β-diOHprog caused precocious spermiation in both species; however, the response to 17α,20β-diOHprog was of lesser magnitude than that to SGA. The spermiation response of goldfish to 17α-hydroxyprogesterone was similar to that of 17α,20β-diOHprog. Neither testosterone nor 11-ketotestosterone were effective in inducing spermiation in amago salmon, but these steroids were found to be slightly effective in goldfish. Effects of a single injection of SGA on changes in serum levels of 17α,20β-diOHprog and 11-ketotestosterone were also examined in nonspermiating amago salmon. Serum levels of 17α,20β-diOHprog dramatically increased after treatment and peaked on Day 2 and thereafter declined quickly. Similarly, 11-ketotestosterone peaked on Day 2, but the levels remained high throughout the experimental period. Considered together, these findings are consistent with the suggestion that 17α,20β-diOHprog is involved in the process of spermiation in teleosts. It is further suggested that this hormone is a testicular steroidal mediator of gonadotrophin-induced spermiation in amago salmon.     

CASE OF INFLAMMATORY FIBROID POLYP OF THE ESOPHAGOGASTRIC JUNCTION

Upper gastrointestinal endoscopy of a 25‐year‐old man with heartburn revealed an elevated lesion in the esophagogastric junction (EGJ). Piecemeal endoscopic mucosal resection (EMR) followed by histopathological examination led to a diagnosis of inflammatory fibroid polyp (IFP). After EMR, the heartburn persisted despite giving a proton pump inhibitor (PPI), and the residual lesion gradually enlarged and a transverse mucosal break developed on the esophageal side of it. However, the combined administration of the PPI and an H2 receptor antagonist reduced the heartburn, and led to endoscopic regression of the lesion and disappearance of the transverse mucosal break. IFP of the esophagogastric junction is extremely rare, and this case is interesting in that potent inhibition of gastric acid secretion resulted in the regression of the lesion.     

Pouch operation for rectal cancer

Many retrospective studies have found that the functional outcome after a low anterior resection for rectal cancer is better with colonic J-pouch reconstruction than with conventional straight anastomosis. This advantage was demonstrated in prospective, randomized trials and meta-analyses. However, despite its increasing popularity there are several areas of controversy about the use of the colonic J-pouch reconstruction. These issues include anastomotic leaks, the part of the colon used for the pouch, the pouch size, causes of difficulty in evacuation, indications (the optimum level of anastomosis), appropriateness for the elderly, and long-term (2 years or more after surgery) functional outcome. All relevant articles identified from MEDLINE databases were reviewed. The incidence of anastomotic leaks is apparently reduced by colonic J-pouch reconstruction. A 5-cm colonic J-pouch using the sigmoid colon increases the reservoir function without compromising evacuation, and provides better functional outcome than straight anastomosis, even 2 years or more after surgery, in patients whose anastomosis is less than 8 cm from the anal verge. Patients with ultralow anastomoses, less than 4 cm from the verge, appear to benefit the most. At a time when the indications for abdominoperineal excision appear to be reduced for low rectal cancer, the demand for colonic J-pouch reconstruction (the best technique in pouch operations) is therefore likely to increase.     

Factors on delayed recovery of otitis media with effusion in children--clinical and bacteriological study

The resolution of middle ear effusions (MEE) of children with otitis media with effusion (OME) who underwent myringotomy for the bacteriological examination was analyzed in terms of the culture results and the clinical features. The present study consisted of 193 children (258 ears), and the MEE from 77 ears (30%) were culture positive and the respiratory pathogens were detected from 44 ears (17%). Each child was then assigned to receive either a more than two-week course of antibiotics, cefaclor (CCL) or not. At one month following entry, 53 (55%) out of 97 ears in CCL-treated group were effusion-free compared with 31 (40%) out of 78 ears in the control group (P less than 0.05). In the control group, the resolution of MEE was significantly poor in the recurrent cases and the cases with pathogen positive-MEE. The presence of accompanying diseases such as adenoid vegetation, chronic sinusitis and allergy, however, was not related to the resolution of MEE. On the other hand, the cure rate of the cases with pathogen positive-MEE and recurrent cases in the CCL-treated group showed significant improvement. Furthermore, the cases accompanying adenoid vegetation and chronic sinusitis tended to become effusion-free after the antibiotic treatment. Therefore, the persistent bacterial infection in the middle ear and/or surrounding organs such as adenoid plays possibly an important role in the delayed recovery of OME. Antibiotics treatment could increase, to some extent, the resolution of MEE in cases with OME.     

Chronic evaluation of the Cleveland Clinic CorAide left ventricular assist system in calves

The Cleveland Clinic CorAide left ventricular assist system is based on a third-generation, implantable, centrifugal pump in which a rotating assembly is suspended fully. To evaluate chronic in vivo system performance and biocompatibility, the CorAide blood pump was implanted in 18 calves for either 1 month or 3 months. Hemodynamics were stable in all calves with a mean pump flow of 5.9 +/- 1.2 L/min and a mean systemic arterial pressure of 98 +/- 5 mm Hg. There were no incidences of bleeding, organ dysfunction, or mechanical failure in any of the 18 calves. Hemolysis occurred in only 1 calf due to outflow graft stenosis. Thrombus inside the pump, seen in 4 of the first 6 cases, was totally eliminated by a final redesign in the remaining cases, including the last 6 implants conducted without anticoagulation therapy. The CorAide blood pump demonstrated good biocompatibility and reliable, effective system performance.