Influence of acidic metabolic environment on differentiation of stem cell-derived cardiomyocytes.

Stem cell-based myocardial regeneration is a frontier topic in the treatment of myocardial infarction. Manipulating the metabolic microenvironment of stem cells can influence their differentiation into cardiomyocytes, which have promising clinical applications. pH is an important indicator of the metabolic environment during cardiomyocyte development. And lactate, as one of the main acidic metabolites, is a major regulator of the acidic metabolic environment during early cardiomyocyte development. Here, we summarize the progress of research into the influence of pH value and lactate on cardiomyocyte survival and differentiation, as well as related mechanisms.

Mid- and long-term efficacy of off-pump coronary artery bypass grafting in elderly patients with coronary artery disease complicated with moderate ischemic mitral regurgitation / 中国胸心血管外科临床杂志

@# Objective     To analyze the efficacy of off-pump coronary artery bypass grafting (OPCABG) in elderly patients with coronary artery disease complicated with moderate ischemic mitral regurgitation. Methods     The clinical data of patients aged≥70 years with coronary artery disease complicated with moderate mitral regurgitation, and undergoing OPCABG from January 2009 to January 2020 in Beijing Anzhen Hospital were retrospectively analyzed. The echocardiographic indicators of the patients were compared preoperatively, postoperatively before discharge and during the follow-up. Results     Finally 239 patients were enrolled. There were 136 males and 103 females, aged 74.1±3.2 years. Before postoperative discharge, 49 (20.5%) patients had no mitral regurgitation, 144 (60.3%) mild regurgitation, 46 (19.2%) moderate regurgitation, and 0 severe regurgitation. The area of mitral regurgitation was significantly improved (2.5±1.8 cm2 vs. 5.6±1.0 cm2, P<0.001). There were 10 (4.2%) patients of hospital death, 23 (9.6%) of low cardiac output, 3 (1.3%) of myocardial infarction, and 8 (3.3%) of nervous system injury after operation. As a result, 208 (90.8%) patients were followed up and the mean follow-up time was 3.4 years (range 1-9 years). The cumulative survival rates at postoperative 2, 4, 6, and 8 years were 95.8%, 88.0%, 78.4%, and 73.1%, respectively. Postoperative follow-up showed significant improvements compared with those before surgery in the area of mitral regurgitation, left ventricular ejection fraction, left ventricular end-diastolic and left ventricular end-systolic diameters (all P<0.05). Duirng the follow-up, the major adverse cardiac and cerebrovascular events were all cause death in 22 (10.6%) patients, including cardiac death in 17 (8.2%) patients, myocardial infarction in 7 (3.4%) patients, heart failure in 24 (11.5%) patients, cerebrovascular events in 11 (5.3%) patients, re-hospitalization due to heart disease in 23 (11.1%) patients, and none of the patients with myocardial infarction were revascularized. Conclusion     The mid- and long-term outcomes of OPCABG in the treatment for elderly patients with coronary artery disease complicated with moderate ischemic mitral regurgitation is good.

Effect of CDM3 on the co-culture of human induced pluripotent stem cells with matrigel-coated polycaprolactone to make cardiac patch / 中国胸心血管外科临床杂志

@#Objective    To provide experimental data and theoretical support for further studying the maturity of cardiac patches in other in vitro experiments and the safety in other in vivo animal experiments, through standard chemically defined and small molecule-based induction protocol (CDM3) for promoting the differentiation of human induced pluripotent stem cells (hiPSCs) into myocardium, and preliminarily preparing cardiac patches. Methods    After resuscitation, culture and identification of hiPSCs, they were inoculated on the matrigel-coated polycaprolactone (PCL). After 24 hours, the cell growth was observed by DAPI fluorescence under a fluorescence microscope, and the stemness of hiPSCs was identified by OCT4 fluorescence. After fixation, electron microscope scanning was performed to observe the cell morphology on the surface of the patch. On the 1st, 3rd, 5th, and 7th days of culture, the cell viability was determined by CCK-8 method, and the growth curve was drawn to observe the cell growth and proliferation. After co-cultured with matrigel-coated PCL for 24 hours, hiPSCs were divided into a control group and a CDM3 group, and continued to culture for 6 days. On the 8th day, the cell growth was observed by DAPI fluorescence under a fluorescence microscope, and hiPSCs stemness was identified by OCT4 fluorescence, and cTnT and α-actin for cardiomyocyte marker identification. Results    Immunofluorescence of hiPSCs co-cultured with matrigel-coated PCL for 24 hours showed that OCT4 emitted green fluorescence, and hiPSCs remained stemness on matrigel-coated PCL scaffolds. DAPI emitted blue fluorescence: cells grew clonally with uniform cell morphology. Scanning electron microscope showed that hiPSCs adhered and grew on matrigel-coated PCL, the cell outline was clearly visible, and the morphology was normal. The cell viability assay by CCK-8 method showed that hiPSCs proliferated and grew on PCL scaffolds coated with matrigel. After 6 days of culture in the control group and the CDM3 group, immunofluorescence showed that the hiPSCs in the control group highly expressed the stem cell stemness marker OCT4, but did not express the cardiac markers cTnT and α-actin. The CDM3 group obviously expressed the cardiac markers cTnT and α-actin, but did not express the stem cell stemness marker OCT4. Conclusion    hiPSCs can proliferate and grow on matrigel-coated PCL. Under the influence of CDM3, hiPSCs can be differentiated into cardiomyocyte-like cells, and the preliminary preparation of cardiac patch can provide a better treatment method for further clinical treatment of cardiac infarction.

Experimental study on co-culture of DiI labeled rat bone marrow mesenchymal stem cells and polycaprolactone film in vitro to make a cell patch.

BACKGROUND: In stem cell therapy, due to the lack of an effective carrier, a large number of transplanted stem cells are lost and die. Therefore, finding a suitable carrier has become a further direction of stem cell therapy. OBJECTIVE: In research on the co-culture of polycaprolactone (PCL) with 1,1'-Dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiI) labeled bone marrow mesenchymal stem cells (BMSCs), we observe the effect of materials on the growth and proliferation of DiI labeled stem cells, and the effect of DiI labeling on patch preparation, so as to find a kind of biomaterial suitable for the growth and proliferation of BMSCs, and find a suitable cell carrier for stem cell therapy of myocardial infarction and in vivo tracing. METHODS: Clean grade Sprague Dawley rats were selected as experimental objects, BMSCs were isolated and cultured, and the surface markers were identified by flow cytometry. After the BMSCs were cultured for 3 passages, the BMSCs were stained with DiI dye, and the BMSCs DiI and PCL biomaterial film were co-cultured. After 24 hours, the cell growth was observed under fluorescence microscope, and fixed for scanning under electron microscope. The cell proliferation was detected by CCK-8 at 1, 4, 7, 10 days of culture. The measurement data conforming to normal distribution are expressed in the form of mean ± standard deviation (X¯± s). One way ANOVA was used for comparison among groups, LSD analysis was used for pairwise comparison. The difference was statistically significant (P < 0.05). RESULTS: BMSCs were strongly positive for CD90, CD44H, but negative for CD11b/c, CD45. Under fluorescence microscope, BMSCs DiI showed red light, fusiform or polygonal. Under the scanning electron microscope, the cell patch formed by co-culture of PCL film and DiI-BMSCs had a large number of cells on the surface and normal cell state. CCK-8 assay showed that the OD value on the first day was 0.330 ± 0.025; The OD value was 0.620 ± 0.012 on the 4th day, 1.033 ± 0.144 on the 7th day and 1.223 ± 0.133 on the 10th day. There was significant difference among the time points (P < 0.05). CONCLUSIONS: The cell patch made of PCL film and DiI labeled BMSCs can survive and proliferate on the surface, so it can be used as a scaffold material for stem cell therapy in vivo.

Risk factors of early death and long-term outcomes in myocardial infarction complicated with ventricular septal rupture / 中华老年医学杂志

Objective:To analysis the risk factors of early death and long-term outcomes of myocardial infarction complicated with ventricular septal rupture.Methods:A total of 135 patients with myocardial infarction complicated with ventricular septal rupture in Beijing Anzhen Hospital from January 2008 to December 2020 were retrospectively analyzed.According to the survival or death within 30 days after ventricular septal rupture, the patients were divided into the early survival group(n=71)and the early death group(n=64). The clinical characteristics of the two groups were observed, and the risk factors for early death group were analyzed.The long-term outcomes of the surgery group(n=69)and the non-surgery group(n=66)was analyzed.Results:The early mortality rate of patients with myocardial infarction complicated with ventricular septal rupture was 47.4%(64/135). Univariate analysis showed that age, sex, white blood cell count, platelet count, C-reactive protein level, left ventricular end-diastolic diameter, abnormal liver function, pulmonary infection, no surgery repair and Killip grade ≥3 were associated with early death as compared with the early survival group(all P<0.05). Multivariate regression analysis showed that no surgery repair( OR=16.103, 95% CI: 4.400-58.930, P<0.001)and Killip≥3 grade( OR=9.014, 95% CI: 2.506-32.428, P=0.001)and abnormal liver function( OR=5.171, 95% CI: 1.388-19.264, P=0.014)were independent risk factors for early death in patients with myocardial infarction complicated with ventricular septal rupture.During follow-up of 1.0 to 11.8(median 3.2)years, the 2-year and 10-year cumulative survival rates were significantly higher in the surgery group than in the non-surgery group(76.7% vs.16.7%, P<0.001; 73.1% vs.16.7%, P<0.001). Conclusions:No surgical repair, Killip grade ≥3 and abnormal liver function are independent risk factors for early death in patients with myocardial infarction complicated with ventricular septal rupture.The long-term outcomes of surgical treatment for myocardial infarction complicated with ventricular septal rupture is good.

Advances in research on the effects of microenvironment on the differentiation of stem cells into cardiomyocytes / 中华胸心血管外科杂志

Microenvironment has a major impact on stem-cell differentiation. Stem-cell differentiation achieved by controlling the microenvironment is more similar to physiological characteristic than the traditional chemical induction, which will undoubtedly have a broader clinical application prospect. The impact of microenvironment on stem cell to cardiomyocyte differentiation is reviewed in this paper.

In vitro three-dimensional coculturing poly3-hydroxybutyrate-co-3-hydroxyhexanoate with mouse-induced pluripotent stem cells for myocardial patch application.

Identifying a suitable polymeric biomaterial for myocardial patch repair following myocardial infarction, cerebral infarction, and cartilage injury is essential. This study aimed to investigate the effect of the novel polymer material, poly3-hydroxybutyrate-co-3-hydroxyhexanoate, on the adhesion, proliferation, and differentiation of mouse-induced pluripotent stem cells in vitro. Mouse-induced pluripotent stem cells were isolated, expanded, and cultured on either two-dimensional or three-dimensional poly3-hydroxybutyrate-co-3-hydroxyhexanoate films (membranes were perforated to imitate three-dimensional space). Following attachment onto the films, mouse-induced pluripotent stem cell morphology was visualized using scanning electron microscopy. Cell vitality was detected using the Cell Counting Kit-8 assay and cell proliferation was observed using fluorescent 4',6-diamidino-2-phenylindole (DAPI) staining. Mouse-induced pluripotent stem cells were induced into cardiomyocytes by differentiation medium containing vitamin C. A control group in the absence of an inducer was included. Mouse-induced pluripotent stem cell survival and differentiation were observed using immunofluorescence and flow cytometry, respectively. Mouse-induced pluripotent stem cells growth, proliferation, and differentiation were observed on both two-dimensional and three-dimensional poly3-hydroxybutyrate-co-3-hydroxyhexanoate films. Vitamin C markedly improved the efficiency of mouse-induced pluripotent stem cells differentiation into cardiomyocytes on poly3-hydroxybutyrate-co-3-hydroxyhexanoate films. Three-dimensional culture was better at promoting mouse-induced pluripotent stem cell proliferation and differentiation compared with two-dimensional culture.

Meta-Analysis of Medium and Long-Term Efficacy of Loading Statins After Coronary Artery Bypass Grafting.

BACKGROUND: The aim of this study was to evaluate the medium- and long-term efficacy of loading statins after coronary artery bypass grafting (CABG) by comparing using a loading dose of statins or a regular dose of statins in patients undergoing CABG. METHODS: We conducted a literature search of numerous databases for randomized controlled trials on the efficacy of a loading dose of statins in patients undergoing CABG. The quality of included studies was evaluated according to the Newcastle-Ottawa Scale. Statistical results of treatment were represented by weighted mean difference, odds ratio, and 95% confidence interval. RESULTS: There were 8 studies including 8,676 patients (4,352 who had a loading dose of statins and 4,324 who had a regular dose). Meta-analysis showed statistically significant differences in the following in patients who took a loading dose of statins: lower level of low-density lipoprotein cholesterol (LDL-C) after CABG (p < 0.00001), fewer deaths caused by myocardial infarction (p = 0.005), fewer patients with myocardial infarction (p = 0.004), fewer patients undergoing secondary CABG (p < 0.00001), and fewer patients undergoing graft restenosis by intravascular ultrasonography (p < 0.0001). CONCLUSIONS: Comparing patients receiving a loading dose of statins with those receiving a regular dose after CABG, the medium- and long-term efficacy of a loading dose showed significant reduction in LDL-C, lower occurrence of adverse cardiac events, and reduction in graft restenosis. Although the incidence of drug-related side effects was slightly higher in the loading-dose group, in the majority of patients they were not serious. Overall, a loading dose of statins is superior to regular dosing of statins after CABG.

Study on PHBHHx co-cultured with mouse induced pluripotent stem cells for use as myocardial patches in vitro / 中华胸心血管外科杂志

Objective To study the effect of polymer material on adhesion , proliferation and differentiation of mouse in-duced pluripotent stem cells via co-culturing in vitro, to find a suitable polymeric biomaterials for miPSCs attachment , prolifera-tion and differentiation , forming myocardial patches as a new repair method for myocardial infarction .Methods miPSCs were recovered, passaged and cultured with PHBHHx two-dimension films and PHBHHx three-dimension films together.The mor-phology of miPSCs attached on the films was visualized under scanning electron microscope ( SEM) .The mouse induced pluri-potent stem cells were induced by differentiation medium that containing vitamin C .Control group did not add any inducer.The survival and differentiation of miPSCs were observed through immunofluorescence and flow cytometry .Results MiPSCs can grow, proliferate and differentiate on PHBHHx films both two-dimension and three-dimension.Vitamin C, as a favourable in-ducer, can markedly improve the efficiency of miPSCs differentiation of cardiomyocytes on PHBHHx films .Immunofluorescence results demonstrated positive cTnT expression.Flow cytometry measured cTnT expression: Vitamin C inducer group(47.54 ± 1.46)%>without any inducer group(7.02 ±0.95)%(PPHBHHx two-dimensional films(53.31 ±1.41)%>traditional cell culture(47.54 ±1.46)%(P<0.05).Conclusion iPSCs can ad-here, survive and differentiate on the PHBHHx film.Vitamin C, as a favourable inducer, can markedly improve the efficiency of miPSCs differentiation of cardiomyocytes .Relative to PHBHHx two-dimensional film culture and traditional culture , the three-dimensional PHBHHx film culture has a great advantage in the process of miPSCs differentiating into myocardial cells .

Meta-analysis of medium-and long-term efficacy of loading statins after coronary artery bypass grafting surgery / 中华胸心血管外科杂志

Objective To evaluate the medium-and long-term efficacy of loading statins after coronary artery bypass grafting surgery by comparing patients undergoing coronary artery bypass grafting surgery(CABG) using a loading dose statins or a regular dose of statins.Methods Cochrane Library, WanFang database etc database web were searched for the efficacy of a loading dose of statins after CABG in randomized controlled trials(RCTs).The quality of included studies was evaluated according to the Newcastle-Ottawa Scale(NOS).The statistical results of treatment were represented by weighted mean difference (WMD) , the odds ratio(OR) and 95％ confidence intervals(CI).Revman 5.2 software was used for data processing and analysis.Results There are eight studies including 8 676 cases, 4 352 cases are in group using a loading dose of statins, 4 324 cases are in group using a regular dose of statins.Meta-analysis showed the level of low-density lipoprotein(LDL-C) in patients who took a loading dose of statins after CABG(WMD =-42.15,95％ CI:-44.45～-39.84, P ＜0.00001);the number of death caused by myocardial infarction (OR =0.74, 95 ％ CI: 0.60～ 0.91, P =0.005);the number of patients occurred myocardial infarction (OR =0.78, 95 ％ CI: 0.66～ 0.92, P =0.004);the number of patients undergoing secondary CABG (OR =0.72, 95％ CI: 0.63～ 0.82, P ＜ 0.00001);the number of patients occurred drug side effects(OR =1.43, 95％ CI: 1.06～ 1.93, P =0.02);the number of patients occurred grafts restenosis by intravascular ultrasound(IVUS) (OR =0.59, 95％ CI: 0.50～0.70, P ＜0.0001).The data above reached statistically significant difference.Conclusion Comparing patients who used a loading dose of statins and those who used a regular dose of statins after CABG.The medium-and long-term efficacy of a loading dose of statins showed significantly reduction of LDL-C;reduction of the occurrence to cardiac events, such as death caused by myocardial infarction, myocardial infarction and secondary CABG;reduction of grafts restenosis.The incidence of drug side effects was a little higher in a loading dose of statin group.But the majority of patients did not show serious drug side effects after using a loading dose of statins.In summary, the medium-and long-term efficacy of a loading dose of statins after CABG is better than that of a regular dose of statins.

Culture effects of mouse induced pluripotent stem cells by three-dimensional films in vitro / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the proliferation and differentiation capacities of mouse induced pluripotent stem cells (miPSCs) cultured in 3-hydroxybutyrate-co-3-hydroxyhexanoate(PHBHHx) three-dimensional films three-dimension films for the purpose of finding a suitable polymeric biomaterials for forming myocardial patches.</p><p><b>METHODS</b>miPSCs were recovered, passaged, cultured and identified, then miPSCs divided into the experimental and control groups. MiPSCs in the experimental group were cultured with PHBHHx three-dimension films. MiPSCs in the control group were cultured with traditional culture dish. Stem cell culture medium or differential medium were added to miPSCs to detecte cell vitality by CCK-8 after 72 hours or to measure the cTnT expression of miPSCs through immunofluorescence or the cTnT expression quantity through flow cytometry after 15 days.</p><p><b>RESULTS</b>Cell activity assay showed that the absorbance values were 0.836 ± 0.038 in the experimental group, 0.312 ± 0.004 in the control group (P<0.05). Scanning electron microscope (SEM) observation showed that miPSCs grew well on the PHBHHx dimensional films with normal shape. Immunofluorescence results demonstrated positive cTnT expression in both groups and flow cytometry measured cTnT expression was (60.32 ± 1.76)% in the experimental group and (47.54 ± 1.46)% in the control group (P<0.05).</p><p><b>CONCLUSIONS</b>miPSCs can survive, proliferate and differentiate on PHBHHx dimensional films. miPSCs proliferation and differentiation capacities are significantly higher in PHBHHx three-dimensional films culture compared with the traditional cell culture.</p>

Comparative study of directional differentiation into cardiomyocytes of human embryonic stem cells and mouse embryonic stem cells / 中华胸心血管外科杂志

Objective Comparatively studying the method,efficiency and anti-hypoxia ability of cardiomyocytes which are directionally induced from human embryonic stem cells and mouse embryonic stem cells in vitro so as to provide an experimental basis for further study of inducing the differentiation of embryonic stem cells into cardiomyocytes in vitro.Methods Human embryonic stem cells are induced into cardiomyocytes by suspension method which dosen't using inducersand adherence method which using inducers respectively.Mouse embryonic stem cells are induced into cardiomyocytes by hanging drop method which dosent using inducers and using inducer respectively.Staining the specific marker cTnT of cardiomyocytes by immunofluorescence.Comparing the time,percentage and beating frequency of cardiomyocytes by counting under the microscope.Using apoptosis-hoechst staining kit to detect the apoptosis ratio of beating cardiomyocytes which have been treated by hypoxia with 24 h.Results The group of hESC without inducers results in that the mean time days of appearing beating cardiomyocytes is (13.9 ± 0.9) days,the percentage is 20.8 ％ and the average frequency of beating is (63.8 ± 5.6) times/min.The group of hESC with inducers results in that the mean time days of appearing beating cardiomyocytes is (13.0 ± 1.1) days,the percentage is 66.7％ and the average frequency of beating is (63.0 ± 7.0) times/min.The group of mESC without inducers results in that the mean time days of appearing beating cardiomyocytes is (14.3 ± 1.0) days,the percentage is 12.5％ and the average frequency of beating is (80.2 ± 3.9) times/min.The group of mESC with inducers results in that the mean time days of appearing beating cardiomyocytes is (12.2 ± 1.2) days,the percentage is 81.3％ and the average frequency of beating is (79.9 ±7.7) times/min.Beating cardiomyocytes of each group are positive to cTnT staining.Different apoptosis ratio are detected of beating cardiomyocytes of each group.Conclusion The four methods can all successfully induce the differentiation of embryonic stem cells into myocardiocytes,and the adherent method of hESC induced with activin A + BMP4 is the first successful induction in China.The groups adding inducers improve the differentiation efficiency more significantly than the groups without adding inducers.Inducing mouse embryonic stem cells into cardiomyocytes is more simple and efficient compared with human embryonic stem cells.Without the presence of other protective factor,anti-hypoxia ability of cardiomyocytes induced from human embryonic stem cells is stronger and the beating time are longer in vitro compared with mouse embryonic stem cells.

The management and risk factors of pericardial effusion after cardiac surgery / 中华胸心血管外科杂志

Objective We aimed to recent experience at our hospital in the diagnosis and treatment of pericardial effusion after cardiac surgery and to identify risk factors for its development.Methods We searched our hospital for patient who had cardiac surgery with cardiopulmonary bypass from January 2002 through December 2010.For patient with pericardial effusion,medical records were reviewed to evaluate its manifestations and management.To identify risk factors for effusion,patients with effusions were compared with patients without effusions.All patients had routine postoperative echocardiographic examination.Results Of 22462 patients identified,509 (2.3％) had pericardial effusion.Compared with patients without pericardial effusion,ages,sex,cardiac function and so on were no significant( P ＞ 0.05 ).Body,valve cardiac diseases,and cardiopulmonary bypass time and so on were significant ( P ＜ 0.05 ).Among 509 patients with pericardial effusion,262 patients (51.4％) of whom had specific symptoms.Clinical features of tamponade were documented in 51 patients( 10.1％ ).Pericardial effusions were evacuated by echocardilgraphy-guided pericardiocentesis ( n =27,10.3％ ) or surgical drainage ( n =15,5.7％ ).Pericardial effusion resolved after left thoracocentesis for pleural effusion in 5 patients ( 1.9％ ) ; The Other patients with pericardial effusion were treated conservatively.Indeperdent risk factors for pericardial effusion were large body,valve cardiac operations,and prolonged cardiopulmonsry bypass.Conclusion In our study,pericardial effusion occurred in 2.3％ of patients,and symptoms were nonspecific.Several factors,mainly related to preoperative characteristics and type of operation,predispose patients to effusion,echocardiography-guided pericardiocentesis is effective and safe in these patients with pericardial effusion.

Clinical outcomes after redo coronary artery bypass grafting / 中华胸心血管外科杂志

Objective Evaluate the clinical outcomes of redo coronary revascularization performed with CABG techniques. Methods During the past 10 years, 51 patients (2.5% in the patients who underwent CABG and OPCABG) received redo coronary revascularization in our hospital. The period between the first and the redo surgeries was ( 15.1±5.8)years. Two different procedures were performed with or without cardiopulmonary bypass for the redo CABG: off-pump procedure (OPCABG) in 10 patients and on-pump procedure (CABG) in 41 patients. Two types of surgical approaches were used: me-dian sternotomy in 43 patients and left thoracotomy in 8 patients. Results Respiratory failure requiring mechanical ventilation occurred in 3 of the 51 patients after the operation, as compared with none in the patients who underwent OPCABG. The mean duration treated in the ICU was (2.2±0.7 ) days and that of hospital admission was( 9.2±2.4) days. Two patients (3.9%)died in hospital, one ease was in the off-pump group and the other was in the on-pump group. The causes of death were thought to be acute myocardial infarction with low output syndrome in 1 case and severe respiratory failure in the other. Complications occurred in 11 patients, including re-thoracotomy for hemostasis in 1 patient, respiratory failure in 3 patients and other complications 7. Postoperative EF was 0.60±0. 06. Complete revascularization was achieved in 44 patients, 6 patients in the offpump group and 38 patients in the on-pump group. Partial revascularization was observed in the additional 7 patients. Conclusion Redo CABG performed with or without cardiopuimonary bypass may provide favorable effects with acceptable safety profile and complete revascularization is achievable.