Biomedical subjects

Jae Won Lee

Publications and source records attributed to Jae Won Lee.

At least 19 recordsLinked to original sources

PubMed2006

Differential expression profiling of genes in a complete hydatidiform mole using cDNA microarray analysis.

OBJECTIVES: To gain a better understanding of the genes involved in the pathogenesis of gestational trophoblastic diseases, we evaluated the genome-wide expression levels of genes in complete hydatidiform mole (H-mole) as compared to normal placenta using cDNA microarray technique. METHODS: The expression profiles of complete H-mole tissues were compared with those of normal placenta using cDNA microarray technique. The data obtained from 10,305 human genes were normalized by the print-tip-based LOWESS method. Significance analysis of microarray (SAM) was used to identify genes with statistically significant changes in expression. The expression levels of genes which showed significant differences between normal early placenta and complete H-mole tissues were further confirmed by RT-PCR. RESULTS: A cDNA microarray analysis consisting of 10,305 human genes revealed significant changes in the expression of 213 genes, with 91 genes being upregulated and 122 being downregulated. SAM revealed significant changes in gene expression, including those associated with signal transduction, cell structure, transcription, and apoptosis. Further RT-PCR analysis of altered gene expression in mole tissues supported the microarray analysis results. We confirmed the upregulation of TLE4, CAPZA1, PRSS25, RNF130, and USP1 in complete H-mole tissues. Moreover, our study provides the first evidence that ELK3, LAMA3, LNK, STAT2, and TNFRSF25 are downregulated in complete H-mole compared to normal early placenta tissues. CONCLUSIONS: These findings provide a large body of information regarding gene expression profiles associated with complete H-mole tumorigenesis and allow the identification of potential targets for tumor prevention or therapy.

DNA, Complementary↗

PubMed2006

Factors associated with in-hospital mortality in patients with acute aortic syndrome involving the ascending aorta.

BACKGROUND: Aortic intramural hematoma (IMH), a variant form of classic dissection (AD), is an increasingly recognized and potentially fatal entity of acute aortic syndrome (AAS). We sought to assess the real impact of increased recognition of IMH on mortality of AAS involving the ascending aorta. METHODS: We evaluated 186 consecutive patients with AAS involving the ascending aorta (57.0+/-13.5 years, 95 females) admitted between January 1993 and March 2003. RESULTS: Final diagnosis was AD in 135 patients and IMH in 51 (27%). Patients with AD were younger (54.0+/-13 vs. 65.6+/-10.7 years, p<0.05) and surgery was more frequently performed (82% vs. 31%, p<0.001). Overall in-hospital mortality was 16% (30/186); both total mortality (19% vs. 8%, p=0.059) and mortality without surgery (71% vs. 9%, p<0.001) was higher in AD. Logistic regression identified the following presenting variables as predictors of mortality: AD (OR 53.0; 95% CI, 6.6-425.4; p<0.001), confusion/coma (OR 20.1; 95% CI, 3.8-107.8; p<0.001), tamponade (OR 5.3; 95% CI, 1.2-24.3; p=0.031), heart failure (OR 8.1; 95% CI, 1.1-61.0; p=0.043), and medical treatment only (OR 17.6; 95% CI, 4.6-67.6, p<0.001). Tamponade was more prevalent in IMH (25% vs. 11%, p=0.038), and was a predictor of higher mortality in both groups. CONCLUSION: IMH comprises of significant proportion of AAS involving the ascending aorta and is an independent variable associated with lower mortality despite lower frequency of surgery. Treatment option including optimal timing of surgery can be individualized based on underlying disease entity of AAS and some clinical features at the initial presentation.

Acute Disease↗

PubMed2006

Effect of data normalization on fuzzy clustering of DNA microarray data.

BACKGROUND: Microarray technology has made it possible to simultaneously measure the expression levels of large numbers of genes in a short time. Gene expression data is information rich; however, extensive data mining is required to identify the patterns that characterize the underlying mechanisms of action. Clustering is an important tool for finding groups of genes with similar expression patterns in microarray data analysis. However, hard clustering methods, which assign each gene exactly to one cluster, are poorly suited to the analysis of microarray datasets because in such datasets the clusters of genes frequently overlap. RESULTS: In this study we applied the fuzzy partitional clustering method known as Fuzzy C-Means (FCM) to overcome the limitations of hard clustering. To identify the effect of data normalization, we used three normalization methods, the two common scale and location transformations and Lowess normalization methods, to normalize three microarray datasets and three simulated datasets. First we determined the optimal parameters for FCM clustering. We found that the optimal fuzzification parameter in the FCM analysis of a microarray dataset depended on the normalization method applied to the dataset during preprocessing. We additionally evaluated the effect of normalization of noisy datasets on the results obtained when hard clustering or FCM clustering was applied to those datasets. The effects of normalization were evaluated using both simulated datasets and microarray datasets. A comparative analysis showed that the clustering results depended on the normalization method used and the noisiness of the data. In particular, the selection of the fuzzification parameter value for the FCM method was sensitive to the normalization method used for datasets with large variations across samples. CONCLUSION: Lowess normalization is more robust for clustering of genes from general microarray data than the two common scale and location adjustment methods when samples have varying expression patterns or are noisy. In particular, the FCM method slightly outperformed the hard clustering methods when the expression patterns of genes overlapped and was advantageous in finding co-regulated genes. Thus, the FCM approach offers a convenient method for finding subsets of genes that are strongly associated to a given cluster.

Algorithms↗

PubMed2006

Novel technique of aortic valvuloplasty.

OBJECTIVE: The present study was aimed to assess the results of newly developed aortic valve repair technique. METHODS: Between 1997 and 2004, 69 aortic valvuloplasties were performed with a new technique addressing the three main components of the aortic root; leaflets (L), sinotubular junction (STJ), and aortic annulus (A). For leaflet correction, additional leaflets were implanted and for STJ and annular reduction, an internal synthetic ring and strip along the fibrous annulus were implanted, respectively. The patients were divided into two groups: 30 patients with isolated aortic regurgitation (group IAR) were treated by correction of STJ+L (n=21) and STJ+A+L (n=9), and 39 aortic regurgitation patients with annuloaortic ectasia or ascending aortic aneurysm (group AAR) were treated with STJ correction only (n=16), STJ+A (n=6), STJ+L (n=9), and STJ+A+L (n=8). RESULTS: The mean age was 43.4 and 49.5 years for groups IAR and AAR, respectively. There was neither operative nor follow-up death in either group. Suture breakage caused one reoperation in group IAR. Mean follow-up was 13.8 and 20.3 months in groups IAR and AAR, respectively. The preoperative aortic regurgitation grade was 3.67 in group IAR and 2.67 in group AAR. The last follow-up aortic regurgitation grade was 1.1 in group IAR and 1.05 in group AAR. No patient, except for the reoperated patient had AR greater than grade 2. The postoperative pressure gradient was 19.3 mmHg in group IAR and 8. 4mmHg in group AAR. CONCLUSIONS: The results showed this technique to be safe and effective. Thus far broad application of this repair technique has been demonstrated to be highly feasible.

Adult↗

PubMed2006

Structured polychotomous machine diagnosis of multiple cancer types using gene expression.

MOTIVATION: The problem of class prediction has received a tremendous amount of attention in the literature recently. In the context of DNA microarrays, where the task is to classify and predict the diagnostic category of a sample on the basis of its gene expression profile, a problem of particular importance is the diagnosis of cancer type based on microarray data. One method of classification which has been very successful in cancer diagnosis is the support vector machine (SVM). The latter has been shown (through simulations) to be superior in comparison with other methods, such as classical discriminant analysis, however, SVM suffers from the drawback that the solution is implicit and therefore is difficult to interpret. In order to remedy this difficulty, an analysis of variance decomposition using structured kernels is proposed and is referred to as the structured polychotomous machine. This technique utilizes Newton-Raphson to find estimates of coefficients followed by the Rao and Wald tests, respectively, for addition and deletion of import vectors. RESULTS: The proposed method is applied to microarray data and simulation data. The major breakthrough of our method is efficiency in that only a minimal number of genes that accurately predict the classes are selected. It has been verified that the selected genes serve as legitimate markers for cancer classification from a biological point of view. AVAILABILITY: All source codes used are available on request from the authors.

Algorithms↗

PubMed2006

Single nucleotide polymorphisms of the TGFB1 gene and lung cancer risk in a Korean population.

The present study was conducted to investigate the association between single nucleotide polymorphisms (SNPs) of the transforming growth factor-beta 1 (TGFB1) gene and susceptibility to lung cancer and the clinical effect of the SNPs on lung cancer progression in a Korean population. Two polymorphisms in the promoter region of the TGFB1 (T-1572C, C-509T), and one SNP in codon 10 (T+869C) were determined using a SNaPshot primer extension assay in 194 Korean lung cancer patients and 283 normal controls. The polymorphic allele frequencies of A-1572G, C-509T, and T+869C were similar among lung cancer patients (0.52, 0.47, and 0.47, respectively) and controls (0.54, 0.46, and 0.44, respectively). When the data was stratified for smoking history, patients who smoked heavily and had heterozygous C-509T and T+869C genotypes showed an increased lung cancer risk (odds ratio OR = 3.77, confidence interval 95% CI = 1.25-11.30, P = 0.017; OR = 3.61, 95% CI = 1.21-10.74, P = 0.021 for each), after adjustment for age and sex. When heterozygous and homozygous variants for each SNPs were analyzed together, patients who were smokers and had variant genotypes also showed increased risk compared to the reference group. Further analyses to test the effect of the SNPs on the clinical parameters did not reveal an association of each polymorphic allele to the tumor stage or response to treatment. In addition, DNA fragments containing polymorphic genotype of the promoter region (-509T) showed increased transcriptional activity in luciferase assays using non-small cell lung cancer cell lines. In conclusion, this study suggests that heavy smokers in this Korean population who have specific polymorphic variants, which have been associated with increased transcriptional activity of TGFB1, might be more vulnerable to lung cancer.

Base Sequence↗

PubMed2006

Comparison of various statistical methods for identifying differential gene expression in replicated microarray data.

DNA microarray is a new tool in biotechnology, which allows the simultaneous monitoring of thousands of gene expression in cells. The goal of differential gene expression analysis is to identify those genes whose expression levels change significantly by the experimental conditions. Although various statistical methods have been suggested to confirm differential gene expression, only a few studies compared the performance of the statistical tests. In our study, we extensively compared three types of parametric methods such as T-test, B-statistic and Bayes T-test and three types of non-parametric methods such as samroc, significance analysis of microarray and a modified mixture model using both the simulated datasets and the three real microarray experiments.

Gene Expression↗

PubMed2006

Mid-term follow up of patients using the St. Jude Medical Aortic Connector System for proximal vein graft in CABG.

The aortic connector system may reduce stroke during proximal venous anastomosis. However, the overall anastomotic patency rate has been generally reported to be low. From October 2002 to March 2004, 68 patients who received proximal anastomosis using the St. Jude Aortic Connector System were included in the study. There were 47 men and 21 women and their mean age was 65.68+/-6.68 yr old (52 to 85 yr). Grafts were evaluated by coronary angiography or multi-slice 16 channel 3-D CT at 6 days and at 6 months postoperatively. In the immediate postoperative period, no stenosis was observed by either angiography (n=22) or 3D CT (n=46). At 6-month postoperatively, we performed either angiography (n=7) or 3-D CT (n=52). Of these patients, 5 patients showed graft stenosis in the midportion, and 3 in the ostium. There were no stroke. Simple, and effective proximal anastomosis with good protection from cerebrovascular accident was achieved especially when calcification or atheromatous plaque was observed at the ascending aorta in the operation room. However, our mid term patency results raise concerns related to venous graft stenosis in the midportion. Therefore, longer follow up is recommended.

Aged↗

PubMed2005

Interleukin-1B (IL-1B) polymorphisms and gastric mucosal levels of IL-1beta cytokine in Korean patients with gastric cancer.

Interleukin-1B and IL-1 receptor antagonist gene polymorphisms are associated with an increased risk of gastric cancer (GC) in Caucasian populations. However, recent studies could not find any association between IL-1B-511T polymorphism and the risk of GC in Asians. We tested for an association between IL-1 loci polymorphisms with increased gastric mucosal levels of IL-1beta and an increased risk of developing GC in a Korean population. Polymorphisms of IL-1A-889, IL-1B-31, IL-1B-511 and IL-1RN were genotyped in 434 controls and 234 patients with GC. Mucosal IL-1beta cytokine was measured using an ELISA. The frequencies of IL-1A, IL-1B-511, IL-1B-31 and IL-1RN were not statistically different between controls and all patients with GC. After subclassification of GC, only patients with intestinal-type GC showed a higher frequency of IL-1B-31T homozygotes (OR = 2.2; 95% CI = 1.1-4.3) compared with controls. Risk was also significantly increased in these patients for IL-1B-31T homozygotes compared with patients with diffuse-type GC (OR = 3.4; 95% CI = 1.5-7.7). As in Caucasian populations, linkage disequilibrium between IL-1B-31 and IL-1B-511 was nearly complete, but the pattern of haplotype related to the risk of GC (IL-1B-31T/IL-1B-511C) was opposite (IL-1B-511T/IL-1B-31C). Mucosal IL-1beta levels in H. pylori-infected GC patients were higher in patients homozygous for IL-1B-31T compared with IL-1B-31C/T and IL-1B-31C/C. Thus, the combined effects of H. pylori infection and IL-1B-31T/IL-1B-511C polymorphisms with enhanced mucosal IL-1beta production contributed to the development of intestinal-type GC in this Korean population.

Adult↗

PubMed2005

Bootstrap tests for overdispersion in a zero-inflated Poisson regression model.

Ridout, Hinde, and Demétrio (2001, Biometrics 57, 219-223) derived a score test for testing a zero-inflated Poisson (ZIP) regression model against zero-inflated negative binomial (ZINB) alternatives. They mentioned that the score test using the normal approximation might underestimate the nominal significance level possibly for small sample cases. To remedy this problem, a parametric bootstrap method is proposed. It is shown that the bootstrap method keeps the significance level close to the nominal one and has greater power uniformly than the existing normal approximation for testing the hypothesis.

Biometry↗

PubMed2005

Analysis of recurrent mitral regurgitation after mitral valve repair.

Mitral valve repair was performed in 437 patients with mitral regurgitation from January 1994 to January 2002. The causes of mitral regurgitation were degenerative in 238 (54%), rheumatic in 134 (31%), and others in 65 (15%). The most frequently employed surgical techniques were ring annuloplasty in 417 (95%) cases, new chordae formation in 216 (50%), and quadrangular resection in 117 (27%). The mean follow-up was 29.04 +/- 22.81 months. There were 5 (1.2%) early and 5 (1.2%) late deaths. The reoperation rate was 1.6% with 41 (9%) cases of recurrent mitral regurgitation. Of these 22 were procedure-related: incomplete repair in 13, discordant new chordal length in 7, suture dehiscence and leaflet perforation in 1 case each. There were 19 cases of valve related failures: progression of rheumatic disease in 18 and subacute infective endocarditis in 1. Valve-related failure strongly correlated with progression of rheumatic disease. As initial operative success was the prime determinant of repair durability, intraoperative repair assessment with transesophageal echocardiography was essential.

Adolescent↗

PubMed2005

Epicardial microwave application in chronic atrial fibrillation surgery.

The search for alternative epicardial energy sources in the treatment of nonvalvular atrial fibrillation (AF) is a relatively new aspect of the evolving spectrum of Maze operations. We tested the hypothesis that epicardial microwave ablation produces identical results to those of the standard cryosurgical Maze. Fourteen consecutive patients with chronic AF underwent on-pump epicardial Maze procedures after routine cardiac surgery. The results were compared with those of 14 control patients selected from our Maze database of 280 patients. There were no differences in age, sex, cardiothoracic ratio, duration of AF, pump time, intensive care unit or hospital stays. The aortic cross clamp time with epicardial microwave was, however, shortened from 110 to 65 minutes (p=0.011). The recurrence rate of AF after discharge showed no significant difference between the two groups (14% vs. 15%, p=0.841). Epicardial microwave ablation might be a valuable alternative to the conventional cryosurgical Maze procedure, especially for those patients without associated mitral valve disease.

Age Distribution↗

PubMed2004

Heart transplantation. A retrospective analysis of the long-term results.

Long-term results of orthotopic heart transplantation vary among different institutions. The purpose of the present study was to assess the factors, which might affect long-term survival and complications. Between November 1992 and July 2003, 112 heart transplantations (M/F=89:23) were performed. The standard technique was used in the first 57 patients and the bicaval technique in the latter 55 patients. Indications for transplantation in decreasing order of frequency were dilated cardiomyopathy (75%), ischemic cardiomyopathy (7%), and others (18%). The mean follow up duration was 51.8 +/- 31.3 months with 98 patients remaining alive. Preoperatively, all patients were either in NYHA functional class III or IV. Postoperatively, all patients showed improvement to functional class II or I, except 3 patients that remained in NYHA class III. The mean number of rejection cases within the first year was 0.6 +/- 0.8, with humoral rejection noted in 3 cases. The graft vascular disease (GVD)-free survival at 3 and 5 years was 96% and 83%, respectively. The 7-year survival after heart transplantation was 84%. There were 16 deaths, of which infection (n=4) was the most common followed by rejection (n=3), and malignancy (n=2). The present long-term results, were relatively superior to those seen in western countries. The relatively low GVD-free survival rate is thought to have contributed. The complications encountered after transplantation were mostly immunosuppressive drug related, suggesting further potentials for improvement in long-term survival.

Adult↗

PubMed2004

Excellent results for atrial fibrillation surgery in the presence of giant left atrium and mitral valve disease.

OBJECTIVE: The incidence of sinus conversion in the enlarged left atrium after atrial fibrillation surgery is reported to be low. The purpose of the current study was to investigate the effects of atrial fibrillation surgery on mitral valve disease associated with a giant left atrium (GLA). METHOD: From July of 1997 to February of 2002, 188 patients received mitral valve and atrial fibrillation surgery. The patients were placed in either GLA group (n = 94), or NGLA group (n = 94), based on LA size. The presence and onset of sinus rhythm and the incidence and velocity of transmitral A waves were monitored during the early postoperative period and throughout the follow up period of 42 months. RESULTS: The onset of postoperative sinus rhythm was slightly earlier in the NGLA group than in the GLA group at 1.3+/-0.4 days versus 3.1+/-1.2 days, respectively, (P = 0.008). The sinus conversion rates in the GLA and the NGLA groups were 91.5 and 97.9% in the early postoperative period, and 94.7 and 95.7% at 6 months after surgery, respectively. A wave appearance rates in the early postoperative period in the GLA and the NGLA groups were 62.2 and 71.7%, and continued to improve over time to 94 and 95% by 36 months, respectively. Peak A wave velocities in the early postoperative period in GLA and NGLA groups were 67.4+/-34.0 and 61.1+/-29.5 cm/s without significant change during the follow up. CONCLUSION: The results suggest that atrial fibrillation surgery is effective at inducing sinus rhythm and restoring left atrial contractile function after concomitant mitral valve surgery regardless of LA size.

Atrial Fibrillation↗

PubMed2004

Clinical significance of variceal hemorrhage in recent years in patients with liver cirrhosis and esophageal varices.

BACKGROUND AND AIMS: Recent progress in the treatment of variceal bleeding might have reduced the impact of variceal bleeding on survival in patients with esophageal varices. We conducted a retrospective cohort study in an attempt to re-evaluate the clinical significance of variceal bleeding. METHODS: A cohort of 304 patients with liver cirrhosis and esophageal varices, who had no previous history of variceal bleeding and no prophylactic therapy, was studied. RESULTS: During a median follow-up period of 32 months, 55 patients (18%) bled from varices and 111 (37%) died. Variceal hemorrhages accounted for 15% of total deaths. The mortality of first variceal bleeding was 25% in the whole group, but was remarkably different depending on liver function at the time of bleeding (0% in grade Child A vs 55% in grade C; P < 0.05). Among the survivors of first bleeding, 30% experienced rebleeding. Form of varix, red color sign and heavy drinking were the independent risk factors for first variceal bleeding. Multivariate analysis revealed that variceal bleeding still had a significant (P < 0.001) impact on death in the whole cohort, when other independent prognostic factors such as age, ascites, encephalopathy, platelet count, serum albumin level and hepatocellular carcinoma were adjusted. Furthermore, in subgroup analyses, variceal bleeding was more strongly (P < 0.001) linked to death in patients with alcoholic cirrhosis than in those with non-alcoholic cirrhosis, and showed a significant association with survival only for the patients in Child grade B. CONCLUSIONS: Variceal bleeding has various prognostic impacts depending on the etiology of cirrhosis or on the degree of liver dysfunction, and this needs to be taken into account in the prophylaxis against first variceal bleeding.

Adult↗

PubMed2004

Peroxynitrite scavenging mode of alaternin isolated from Cassia tora.

Peroxynitrite (ONOO-), formed from the reaction of superoxide (.O2-) and nitric oxide (NO), is a potent oxidant that contributes to the oxidation of various cellular constituents, including lipids, amino acids, sulfhydryls and nucleotides. It can cause cellular injury, such as DNA fragmentation and apoptotic cell death. ONOO- toxicity is also reported to be involved in inflammatory and neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and atherosclerosis. Moreover, the necessity for a strong ONOO- scavenger is important because of the lack of endogenous enzymes that protect against the damage caused by ONOO-. The aim of this study was to evaluate the ability of natural products to scavenge ONOO-. We tested various plant extracts for their ONOO- scavenging activity. Among them, extract from Cassia tora, which is well known as an oriental herb in traditional medicine, showed potent ONOO- scavenging activity. Further analysis identified the phenolic active components, alaternin and nor-rubrofusarin glucose, as potent ONOO- scavengers. Spectrophotometric analysis demonstrated that alaternin and nor-rubrofusarin glucose led to a decrease in the ONOO- -mediated nitration of tyrosine through electron donation. In bovine serum albumin, alaternin, but not nor-rubrofusarin glucose, showed significant inhibition of ONOO- -mediated nitration in a dose-dependent manner. We believe alaternin can be developed as an effective ONOO- scavenger for the prevention of ONOO- -associated diseases.

Cassia↗

PubMed2004

Evaluation of myocardial flow reserve using pharmacological stress thallium-201 single-photon emission computed tomography: is there a difference between total arterial off-pump coronary artery bypass grafting and conventional coronary artery bypass grafting?

BACKGROUND: The advantage of total arterial off-pump coronary bypass grafting (OPCAB) over conventional onpump coronary artery bypass grafting with 1 internal thoracic artery and veins (CCAB) in terms of myocardial flow reserve has not been studied. We studied these procedures using thallium- 201 perfusion single-photon emission computed tomography (Tl-201 perfusion SPECT). METHODS: Between 1997 and 2001, 152 patients were recruited from our database (OPCAB, n = 100; CCAB, n = 52). All patients underwent pharmacological stress Tl-201 perfusion SPECT 3 to 12 months after bypass surgery. Myocardial perfusion was analyzed semiquantitatively with a 5-point scoring system in a 20-segment model (0, normal, to 4, absence of uptake). Summed stress (SSS), rest (SRS), and difference score (SDS) of the entire myocardium as well as average scores (ASS, ARS, ADS) of individual walls (anterior, septal, lateral, and inferior) were compared by Student t test as well as by repeated-measures analysis of variance with Bonferroni correction. RESULTS: The SSS, SRS, and SDS of OPCAB versus those of CCAB were 6.86 +/- 0.72 versus 7.17 +/- 0.92, 3.95 +/- 0.57 versus 3.75 +/- 0.73, and 2.91 +/- 0.47 versus 3.42 +/- 0.74 (P > .05). However, the lateral wall showed lower scores in OPCAB (ASS, 0.18 versus 0.41, P = .015; ARS, 0.12 versus 0.20, P = .168; ADS, 0.06 versus 0.21, P = .031). The septal wall had higher scores in OPCAB (ASS, 0.33 versus 0.12, P = .003; ARS, 0.18 versus 0.07, P = .037; ADS, 0.14 versus 0.04, P = .030). The anterior and inferior walls were not different between the 2 groups. CONCLUSIONS: OPCAB led to results similar to those of CCAB. The better results in the lateral wall have been the effect of grafting radial artery rather than vein. The similarity in myocardial reserve in the inferior wall between the 2 groups needs further study. There was no deleterious effect of off-pump as opposed to on-pump CAB.

Aged↗

PubMed2004

Development of an animal experimental model for a bileaflet mechanical heart valve prosthesis.

The objective of this study was to develop a pre-clinical large animal model for the in vivo hemodynamic testing of prosthetic valves in the aortic position without the need for cardiopulmonary bypass. Ten male pigs were used. A composite valved conduit was constructed in the operating room by implanting a prosthetic valve between two separate pieces of vascular conduits, which bypassed the ascending aorta to the descending aorta. Prior to applying a side-biting clamp to the ascending aorta for proximal grafting to the aortic anastomosis, an aorta to femoral artery shunt was placed just proximally to this clamp. The heart rate, cardiac output, Vmax, transvalvular pressure gradient, effective orifice area and incremental dobutamine stress response were assessed. A dose-dependent increase with dobutamine was seen in terms of cardiac output, Vmax, and the peak transvalvular pressure gradient both in the native and in the prosthetic valve. However, the increment was much steeper in the prosthetic valve. No significant differences in cardiac output were noted between the native and the prosthetic valves. The described pre-clinical porcine model was found suitable for site-specific in-vivo hemodynamic assessment of aortic valvular prosthesis without cardiopulmonary bypass.

Adrenergic beta-Agonists↗