Prediction value study of breast cancer tumor infiltrating lymphocyte levels based on ultrasound imaging radiomics.

Objective: Construct models based on grayscale ultrasound and radiomics and compare the efficacy of different models in preoperatively predicting the level of tumor-infiltrating lymphocytes in breast cancer. Materials and methods: This study retrospectively collected clinical data and preoperative ultrasound images from 185 breast cancer patients confirmed by surgical pathology. Patients were randomly divided into a training set (n=111) and a testing set (n=74) using a 6:4 ratio. Based on a 10% threshold for tumor-infiltrating lymphocytes (TIL) levels, patients were classified into low-level and high-level groups. Radiomic features were extracted and selected using the training set. The evaluation included assessing the relationship between TIL levels and both radiomic features and grayscale ultrasound features. Subsequently, grayscale ultrasound models, radiomic models, and nomograms combining radiomics score (Rad-score) and grayscale ultrasound features were established. The predictive performance of different models was evaluated through receiver operating characteristic (ROC) analysis. Calibration curves assessed the fit of the nomograms, and decision curve analysis (DCA) evaluated the clinical effectiveness of the models. Results: Univariate analyses and multivariate logistic regression analyses revealed that indistinct margin (P<0.001, Odds Ratio [OR]=0.214, 95% Confidence Interval [CI]: 0.103-1.026), posterior acoustic enhancement (P=0.027, OR=2.585, 95% CI: 1.116-5.987), and ipsilateral axillary lymph node enlargement (P=0.001, OR=4.214, 95% CI: 1.798-9.875) were independent predictive factors for high levels of TIL in breast cancer. In comparison to grayscale ultrasound model (Training set: Area under curve [AUC] 0.795; Testing set: AUC 0.720) and radiomics model (Training set: AUC 0.803; Testing set: AUC 0.759), the nomogram demonstrated superior discriminative ability on both the training (AUC 0.884) and testing (AUC 0.820) datasets. Calibration curves indicated high consistency between the nomogram model's predicted probability of breast cancer TIL levels and the actual occurrence probability. DCA revealed that the radiomics model and the nomogram model achieved higher clinical net benefits compared to the grayscale ultrasound model. Conclusion: The nomogram based on preoperative ultrasound radiomics features exhibits robust predictive capacity for the non-invasive evaluation of breast cancer TIL levels, potentially providing a significant basis for individualized treatment decisions in breast cancer.

Subclinical left ventricular systolic dysfunction detected in obstructive sleep apnea with automated function imaging and its association with nocturnal hypoxia.

BACKGROUND: Early detection of left ventricular (LV) dysfunction is crucial in obstructive sleep apnea (OSA) due to its close relationship with cardiovascular diseases. Global longitudinal strain (GLS) derived from automated function imaging (AFI) can precisely assess global longitudinal function. The aim of this study was to determine if LV GLS was reduced in patients with OSA and a normal LV ejection fraction (LVEF) and to assess any associated determinants. METHODS: Polysomnography (PSG) and echocardiography were done in consecutive patients with suspected OSA and normal LVEF in this prospective study. Patients were divided into two groups according to apnea-hypopnea index (AHI) (Group 1, normal or mild OSA: AHI < 15/h; Group 2, moderate-to-severe OSA: AHI ≥ 15/h). Clinical, PSG, and echocardiographic parameters were compared between the two groups and the associated factors were investigated. RESULTS: Of 425 consecutive patients, 244 were analyzed after exclusions. Patients in Group 2 had significantly worse GLS than those in Group 1 (p < 0.001). The prevalence of GLS reduction (defined as < - 19.7%) was 25% and 76%, respectively (χ2 = 34.19, p < 0.001). Nocturnal lowest pulse oxygen saturation (SpO2), AHI, body mass index (BMI), and gender were associated with GLS reduction (all p < 0.05). Further multivariate analysis showed that the lowest SpO2 (OR: 2.15), gender (OR: 2.45), and BMI (OR: 2.66) remained independent (all p < 0.05), and the lowest SpO2 was the most powerful determinant (χ2 = 33.0, p < 0.001) in forward regression analysis. The intra- and inter-operator variability for AFI and coefficient of repeatability was low even in those with relatively poor images. CONCLUSIONS: In patients with normal LVEF, more severe OSA was associated with a worse GLS. The major determinants were lowest nocturnal SpO2, gender, and obesity, but not AHI. GLS can be rapidly and reliably assessed using AFI.

Hollow Magnetic Nanocatalysts Drive Starvation-Chemodynamic-Hyperthermia Synergistic Therapy for Tumor.

Magnetic hyperthermia therapy (MHT) has been considered as an excellent alternative for treatment of deep tumor tissue; however, up-regulation of heat shock proteins (HSPs) impairs its hyperthermal therapeutic effect. Reactive oxygen species (ROS) and competitive consumption of ATP are important targets that can block excessive HSP generation. We developed a magnetic nanocatalytic system comprised of glucose oxidase (GOD)-loaded hollow iron oxide nanocatalysts (HIONCs) to drive starvation-chemodynamic-hyperthermia synergistic therapy for tumor treatment. The Fe2+ present in HIONCs contributed to ROS generation via the Fenton reaction, relieving thermo-resistance and inducing cell apoptosis by chemodynamic action. The Fenton effect was enhanced through the conditions created by increased MHT-related temperature, GOD-mediated H2O2 accumulation, and elevated tumor microenvironment acidity. The HIONCs catalase-like activity facilitated conversion of H2O2 to oxygen, thereby replenishing the oxygen levels. We further demonstrated that locally injected HIONCs-GOD effectively inhibited tumor growth in PC3 tumor-bearing mice. This study presents a multifunctional nanocarrier system driving starvation-chemodynamic-magnetic-thermal synergistic therapy via ROS and oxygen modulation for prostate tumor treatment.

The role of mitochondrial tRNAPhe C628T variant in deafness expression.

Mutations in mitochondrial genome are one of the most important causes of hearing loss, of these, mitochondrial tRNA (mt-tRNA) genes are the hot spots for mutations associated with deafness. Most recently, a novel mt-tRNA(Phe) C628T variant has been reported to be associated with non-syndromic and sensorineural hearing loss. To test this association, we characterized the C628T variant using a phylogenetic approach; in addition, we employed the bioinformatics tool to predict the thermodynamic change of the mt-tRNA(Phe) gene with and without this variant. Intriguingly, the C628T variant was not evolutionary conserved and had little effect on mt-tRNA(Phe) folding. Moreover, through the application of the pathogenicity scoring system, we classified the C628T variant as a "neutral polymorphism", suggesting that this variant currently lacked sufficient evident to support as a "pathogenic" mutation.

Mammotome® biopsy system for the resection of breast lesions: Clinical experience in two high-volume teaching hospitals.

Ultrasound-guided vacuum-assisted breast biopsy (VABB) is regarded as a feasible, effective, minimally invasive and safe method for the removal of benign breast lesions, without the occurrence of serious complications. The aim of this study was to evaluate the feasibility, efficacy and safety of ultrasound-guided VABB using the Mammotome® biopsy system in the treatment of breast lesions. The clinical outcomes of 3,681 patients with breast lesions were evaluated following excisions by ultrasound-guided VABB in two high-volume teaching hospitals. From January 2008 to December 2012, a total of 4,867 ultrasound-guided VABB procedures were performed in the 3,681 patients, who had a mean age of 37.8 years (range, 16-73 years). The parameters examined in this analysis included lesion size, lesion location in the inner breast, Breast Imaging Reporting and Data System (BI-RADS) ultrasound category and histopathological diagnosis. Ultrasonography follow-up was performed at 3-6 month intervals in order to assess recurrence. The size of the investigated lesions ranged between 6 and 62 mm and a histopathological diagnosis was made in 100% of cases. The results indicated that the majority of specimens (98.89%) were benign. On average, the ultrasound-guided VABB was performed in 10.3 min (range, 7.5-43 min) and the mean number of cores removed in the procedure was 8.1 (range, 3-32). A complete excision was achieved in the majority of cases (99.7%). The presence of a hematoma was the most common complication following the biopsy, and was observed in 27.5% of patients. The mean follow-up period was 25.5 months (range, 1-60 months), during which the rate of recurrence was 4.4%. The results indicated that ultrasound-guided VABB using the Mammotome biopsy system is an effective and safe procedure that is able to rapidly remove the majority of benign breast lesions using a small incision and without the occurrence of scarring or complications.

Lack of independent relationship between the MMP-12 gene polymorphism and carotid plaque susceptibility in the Chinese Han population.

The purpose of this study was to investigate whether a polymorphism in the matrix metalloproteinase-12 gene (MMP-12 -82A/G) is correlated with serum protein levels or with the susceptibility for carotid plaques in the Chinese Han population. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed on the -82A/G polymorphism in the MMP-12 gene for 1314 patients with acute cerebral infarctions; 710 of these cases were diagnosed with stable plaques, 340 cases were diagnosed with vulnerable plaques and 264 cases had no plaques. At the same time, serum MMP-12 levels were measured using the enzyme-linked immunosorbent assay (ELISA). Compared to the AA genotype, the frequency of the AG+GG genotypes was not significantly different between the three groups (χ(2) = 1.242, p = 0.537), and the frequency of the G allele of the MMP-12 gene was not different within the three subgroups (χ(2) = 1.218, p = 0.544). There were no significant differences in MMP-12 protein levels among the three groups (F = 0.675, p = 0.510); similarly, there was no difference in MMP-12 protein levels between the stable plaque group and the vulnerable plaque group (p = 0.755). There was also no difference between the vulnerable plaque group and the no plaque group (p = 0.420). The current data suggest that the inter-individual variability in the MMP-12 gene variation may not be a risk factor for vulnerable plaques in the Chinese Han population.

[Association between matrix metalloproteinase-8 -799C/T polymorphism and instability of carotid plaque].

OBJECTIVE: To investigate the association between a -799C/T polymorphism in the promotor region of matrix metalloproteinase-8 (MMP-8) gene and instability of carotid plaque in Chinese Han population. METHODS: A total of 451 acute infarction patients from the Department of Neurology of Taizhou Hospital were divided into carotid vulnerable plaque group and carotid stable plaque group according to the results of carotid B-mode ultrasonography. Serum MMP -8 level was measured by the means of enzyme-linked immunosorbent assay (ELISA). At the same time, the MMP-8 -799C/T polymorphism was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RESULTS: Serum level of MMP-8 in the carotid vulnerable plaque group was higher than that in the carotid stable plaque group (t= 2.894, P= 0.004). The genotype distribution of -799C/T polymorphism between the two groups was significantly different (Chi-square = 13.65, P= 0.000). Serum level of MMP-8 in patients with TT genotype was higher than that in patients with CC genotype (t= 3.141, P= 0.001). CONCLUSION: The present study suggested that serum level of MMP-8 and the -799C/T polymorphism of MMP-8 gene are associated with carotid vulnerable plaque in Chinese Han population, and the T allele may be a predictor for the susceptibility of carotid vulnerable plaque.

Association of a functional polymorphism in the MMP7 gene promoter with susceptibility to vulnerable carotid plaque in a Han Chinese population.

BACKGROUND: Matrix metalloproteinase-7 (MMP-7) may play an important role in the development of vulnerable carotid plaque. An A-to-G transition (-181A/G) in the promoter region of MMP7 is functional in vitro by altering the transcriptional activity of the gene. The aim of this study was to investigate the association between the MMP7 -181A/G polymorphism and vulnerable carotid plaque formation. METHODS: The authors enrolled 641 patients and divided them into three groups according to the carotid ultrasound examination: vulnerable plaque group (n=118), stable plaque group (n=385) and no plaque group (n=138). Traditional atherosclerosis risk factors were recorded and the MMP7 -181A/G polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: In the multinomial logistic regression analysis, compared to the no plaque group, no relationship between MMP7 -181AG+GG genotypes and stable carotid plaque was observed [odds ratio (OR) 1.50; p=0.239]. However, the frequency of AG+GG genotypes was significantly higher in the vulnerable plaque group (OR 2.74; p=0.008). Age was a risk factor for plaque formation, while statin treatment can reduce the prevalence of atherosclerotic plaque. Additionally, using binary logistic regression analysis between the stable and vulnerable plaque groups, this MMP7 polymorphism was associated with vulnerable plaque independently of other factors [OR 1.83; 95% confidence interval 1.08- 3.11; p=0.026]. CONCLUSIONS: The MMP7 -181A/G polymorphism is associated with the development of vulnerable carotid plaques. Age is a risk factor for plaque formation, while statin therapy is associated with a decreased prevalence of carotid atheromatous plaques.

Genotype association of C(-735)T polymorphism of the MMP-2 gene with the risk of carotid atherosclerosis-vulnerable plaque in the Han Chinese population.

The aim of the current study was to explore the possible association of the polymorphism of C(-735)T in MMP-2 with the vulnerable plaque risk in ultrasound-confirmed carotid atherosclerosis cases. Serum MMP-2 levels were measured to investigate the relationship between the MMP-2 level and the genetic variability. The MMP-2 polymorphism was detected by PCR-RFLP in the 243 cases with stable plaque and 221 cases with vulnerable plaque. Serum MMP-2 levels were measured with ELISA. The results showed that MMP-2 was significantly higher in the cases with vulnerable plaque than in the cases with stable plaque. A statistical difference was found between the genotype distributions in the vulnerable plaque cases and that in the stable cases. T-allele frequency was also found to be over-represented in the stable plaque cases than in the vulnerable plaque cases, which might partially explain the observed difference in the serum MMP-2 levels in the different plaque cases. The current results also suggested that MMP-2 was a risk factor in the cases with vulnerable plaques, whereas TT genotype and T allele might be protective factors in the cases with vulnerable plaques.

[Angiogenesis in chronic ischemic porcine myocardium after transfer of VEGF165 and angiopoietin-1 mediated by recombinant adeno-associated viral vector].

OBJECTIVE: To study the effects of combination of angiopoietin-1 (ANG-1) and vascular endothelial growth factor165 (VEGF165) gene transfer mediated by recombinant adeno-associated viral vector on the neovascularization in chronic ischemic porcine myocardium. METHODS: An ameroid constrictor was implanted around the left circumflex coronary artery (LCX) via endoscopy. Six weeks later, coronary angiography revealed that the myocardial ischemia was established by gradual occlusion of the left circumflex coronary artery (LCX). Sixteen swine with the total occlusion or partial stenosis (> 85 %) of the LCX were divided into 4 groups (4 in each group): group I, group II and group IV (control) received direct myocardium injection of rAAV2 VEGF165, rAAV2 ANG-1 or PBS alone, respectively; group III received rAAV2 VEGF165 and rAAV2 ANG-1. Selective coronary angiography and ultrasonography were performed perioperatively to evaluate the cardiac function and the formation of collateral circulation. The expression of VEGF165 and ANG-1 proteins were assessed using ELISA or Western blot. The degree of angiogenesis was assessed by use of immunohistochemical analysis. RESULT: Angiography showed that the occlusion of all LCX was completed or exceeded 95% 6 weeks after ameroid constrictor implantation, indicating the successful establishment of animal model. The expression levels of VEGF165 in group I and III and ANG-1 in groups II and III began to increase at d7 after transfection and reached the peak at d14; then decreased gradually to the normal level after 3 months. The expression levels of VEGF165 in group II and group IV or that of ANG-1 protein in group I and group IV had no markedly changes at different time after transfection. There were significant increase in capillary density and arteriole density and more side branch vessels formed in group III compared with other groups. Echocardiographic measurements showed that the left ventricular systolic function of animals in groups I, II and III increased significantly after gene transfection, especially in group III; but there was no changes in group IV. CONCLUSION: Myocardial perfusion and the left ventricular systolic function are improved after rAAV2 VEGF165 or rAAV2 ANG-1 transfection, which is associated with the angiogenesis in porcine model of chronic myocardial ischemia.

Relation of uric acid levels to aortic root dilatation in hypertensive patients with and without metabolic syndrome.

OBJECTIVE: Uric acid (UA) is considered to be a powerful predictor of cardiovascular risk and hyperuricemia might be involved in the metabolic syndrome (MS). This study aims to investigate the relation between UA levels and aortic root dilatation. METHODS: A total of 348 hypertensive patients [age (67.5+/-9.8) years] with or without MS were included in the study. The aortic root diameters at the aortic annulus, the sinuses of Valsalva, the sinotubular junction, and the proximal part of the ascending aorta were measured using a two-dimensional (2D) echocardiography. Serum UA levels were also measured for all patients. RESULTS: A high UA level is independently associated with aortic root diameters at the sinuses of Valsalva (P=0.001) and the proximal ascending aorta (P<0.0001) in the hypertensive patients without MS. In contrast, aortic root diameters were not significantly related to UA levels in the hypertensive patients with MS. Furthermore, increased UA levels were associated with an increased risk for aortic root dilatation in the patients without MS (sex-adjusted hazard ratio 1.75, 95% confidence intervals (CI) 1.27-2.41), but not in those with MS. CONCLUSIONS: This study demonstrated an independent relationship between the aortic root dimensions and increased levels of serum UA in the hypertensive patients without MS. Further understanding of the mechanisms underlying these associations may allow a clearer interpretation of the potential value of specific urate-lowering treatment on cardiovascular disease.

[Association of the ALOX5AP gene SG13S114 A/T polymorphism with atherosclerosis].

OBJECTIVE: To investigate the relationship between the polymorphism of SG13S114 A/T in the 5-lipoxygenase-activating protein (ALOX5AP) gene and the stability of carotid atherosclerosis. METHODS: Polymorphism of SG13S114 A/T in the ALOX5AP gene was analyzed in 152 cases of acute infarction with stable plaque, and 132 cases of acute infarction with vulnerable plaques, by using polymerase chain reaction and restriction fragment length polymorphism. Carotid artery plaque was analyzed by carotid artery color ultrasound. RESULTS: The frequencies of SG13S114 AA genotype and the A allele in the vulnerable plaque group were higher than that in the stable plaque group (P< 0.01). CONCLUSION: The polymorphism of SG13S114 A/T in the ALOX5AP gene may be associated with the instability of atherosclerosis. And the SG13S114 A allele may be a risk factor of vulnerable plaques.

The relationship between the polymorphism of SG13S114 A/T in ALOX5AP gene and the vulnerability of carotid atherosclerosis in Chinese Han population.

The purpose of this study was to determine the relationship between the polymorphism of SG13S114 A/T in ALOX5AP gene and the vulnerability of carotid atherosclerosis in Chinese Han population. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) of SG13S114 A/T in ALOX5AP gene was performed for 284 patients with atherothrombotic cerebral infarction, of which 152 cases were diagnosed with stable plaque and the other 132 cases had vulnerable plaques. We found that the frequency of SG13S114 AA genotype and A allele of ALOX5AP gene in the cases with vulnerable plaques was significantly higher than those in the cases with stable plaques. These results suggested that high expression of SG13S114 AA genotype was related to the vulnerability of carotid atherosclerosis. SG13S114 A allele may be a risk factor of vulnerable plaques.

Relationship of heavy drinking, lipoprotein (a) and lipid profile to infrarenal aortic diameter.

The objective of this study was to examine the association of alcohol drinking and lipid profile with infrarenal aortic dimension. The diameter of the infrarenal aorta was measured using ultrasound in 395 individuals (mean 66.6 +/- 10.3 years) with atherosclerotic diseases or risk factors. The associations between heavy drinking, serum lipoprotein (a) levels, lipid profile and infrarenal aorta diameters were examined. Heavy drinking and lipoprotein (a) were positively related with infrarenal aortic dimension, while low-density lipoprotein cholesterol (LDL-C)/high-density lipoprotein cholesterol (HDL-C), LDL-C and total cholesterol (TC)/HDL-C were negatively associated with infrarenal aortic diameter (p < 0.05). In addition, there were negative associations of LDL-C/HDL-C, TC/HDL-C and positive associations of HDL-C and apolipoprotein AI (Apo AI) with heavy drinking (p < 0.05). In conclusion, there was a positive association between infrarenal aortic diameters and heavy drinking, as well as lipoprotein (a) levels. Furthermore, the novel and unexpected inverse association between LDL-C/HDL-C, LDL-C, TC/HDL-C and abdominal aortic diameter may suggest a possible role for anti-atherogenic lipid profile (characterized by a higher level of HDL-C and lower level of LDL-C) in aortic dilatation processes, which need to be clarified by further studies.

Diabetes mellitus: is it protective against aortic root dilatation?

OBJECTIVES: There is evidence of a negative association between diabetes and both abdominal aortic aneurysm and aortic diameter. However, little information is available on the relation between diabetes and aortic root diameter. METHODS: We studied 109 patients with type 2 diabetes. Two-dimensional echocardiography was used to measure the aortic root at the aortic annulus, the sinus of Valsalva, the sinotubular junction and the proximal part of the ascending aorta. Measured mean values were compared with 218 age- and sex-matched patients without diabetes. A comparison of the prevalence of aortic regurgitation between the 2 groups was also performed. RESULTS: In patients with diabetes, the mean aortic root dimensions were significantly smaller than in nondiabetic patients (p < 0.05). The prevalence of aortic root dilatation was significantly higher in nondiabetic subjects than in patients with diabetes (9.63 vs. 2.75%; p = 0.025). In the multivariable regression model, diabetes was a significant negative determinant of aortic root size at all measured sites. The prevalence of aortic regurgitation tended to be higher in nondiabetic subjects than in diabetic participants (11 vs. 18.8%); however, the difference did not achieve statistical significance (p = 0.071). CONCLUSIONS: In patients with diabetes, the aortic root dimension is significantly smaller than in patients without diabetes.

Aortic root dilatation is associated with carotid intima-media thickness but not with carotid plaque in hypertensive men.

BACKGROUND: The role of atherosclerosis-related processes in aortic root dilatation (ARD) has not been fully determined. The present study was to assess the relationship between carotid IMT, carotid plaque, and ARD. METHODS: Hypertensive men with ARD (n = 30) were compared with hypertensive men without ARD (n = 52) and normal control subjects (n = 29). Two-dimensional echocardiography was used to measure the aortic root at the aortic annulus, the sinus of Valsalva, the sinotubular junction and the proximal part of the ascending aorta. Carotid IMT and carotid plaque were also assessed by ultrasound. RESULTS: The measured mean carotid IMT was significantly increased in patients with ARD (1.37 +/- 0.80 mm) compared to the subjects without ARD (1.06 +/- 0.54 mm) and healthy control subjects (0.84 +/- 0.44 mm) (P < 0.05). However, no significant differences of the prevalence of carotid plaque were found in the three groups (P > 0.05). Aortic diameters at all levels except for the diameter of the supra-aortic ridge were significantly related to carotid IMT when the hypertensive population was considered (P < 0.05). No significant correlation was found between carotid plaque and aortic root dimension (P > 0.05). CONCLUSION: This study shows that carotid intima-media thickening, but not carotid atherosclerotic plaque, is positively associated with ARD. Further studies to explore the underlying mechanism are awaited.

[Create a standard mini-swine model of chronic ischemic myocardium by thoracoscopy].

OBJECTIVE: To create a standard mini-swine model of chronic ischemic myocardium by endoscopy for the research of gene transfer and stem cell. METHODS: Twenty-three male China experimental minipigs were used, aged from 8 to 11 months with a mean of (9.3 +/- 1.8) months and weighed from 20 to 30 kg with a mean of (29.3 +/- 4.3) kg. The myocardial ischemia was established by gradual occlusion of the left circumflex coronary artery (LCX) with an Ameroid constrictor. The Ameroid constrictor was implanted around LCX by endoscopy. Selective coronary angiography, electrocardiogram and Echo-Doppler study were performed perioperatively to evaluate the degree of stenosis. RESULTS: Chronic ischemic myocardial models were successfully generated in 20 of 23 swine by full-endoscopy. Ameroid constrictors were placed at the LCX accurately. Three swine died of anesthetic accident, cardiac arrhythmia at secondary coronary angiography, and pulmonary infection within 6 weeks after operation respectively. Operation time was 25 to 65 min with a mean of (46 +/- 9) min. The blood loss was 30 to 60 ml with a mean of (55 +/- 12) ml. Six weeks later, coronary angiography revealed the total occlusion and partial stenosis (> 85%) of the LCX occurred in 7 and 13 swine respectively. Cardiac systolic and diastolic dysfunction were found in all swine. The ejection fraction value was (65.0 +/- 6.3)% before operation and (41.0 +/- 9.3)% after operation (P = 0.008). The fractional shortening value was (36.2 +/- 4.3)% before operation and (34.2 +/- 2.3)% after operation (P = 0.027). CONCLUSION: The endoscopic surgery is a less invasive way to create a standard mini-swine model of chronic ischemic myocardium with effective results.