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D Shum-Tim

Publications and source records attributed to D Shum-Tim.

At least 19 recordsLinked to original sources
PubMed2001

Dynamics of extracellular matrix production and turnover in tissue engineered cardiovascular structures.

Appropriate matrix formation, turnover and remodeling in tissue-engineered small diameter vascular conduits are crucial requirements for their long-term patency and function. This complex process requires the deposition and accumulation of extracellular matrix molecules as well as the remodeling of this extracellular matrix (ECM) by matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs). In this study, we have investigated the dynamics of ECM production and the activity of MMPs and TIMPs in long-term tissue-engineered vascular conduits using quantitative ECM analysis, substrate gel electrophoresis, radiometric enzyme assays and Western blot analyses. Over a time period of 169 days in vivo, levels of elastin and proteoglycans/glycosaminoglycans in tissue-engineered constructs came to approximate those of their native tissue counter parts. The kinetics of collagen deposition and remodeling, however, apparently require a much longer time period. Through the use of substrate gel electrophoresis, proteolytic bands whose molecular weight was consistent with their identification as the active form of MMP-2 (approximately 64--66 kDa) were detected in all native and tissue-engineered samples. Additional proteolytic bands migrating at approximately 72 kDa representing the latent form of MMP-2 were detected in tissue-engineered samples at time points from 5 throughout 55 days. Radiometric assays of MMP-1 activity demonstrated no significant differences between the native and tissue-engineered samples. This study determines the dynamics of ECM production and turnover in a long-term tissue-engineered vascular tissue and highlights the importance of ECM remodeling in the development of successful tissue-engineered vascular structures.

Animals↗
PubMed2001

Neonatal aortic arch reconstruction avoiding circulatory arrest and direct arch vessel cannulation.

BACKGROUND: Aortic arch reconstruction in neonates routinely requires deep hypothermic circulatory arrest. We reviewed our experience with techniques of continuous low-flow cerebral perfusion (LFCP) avoiding direct arch vessel cannulation. METHODS: Eighteen patients, with a median age of 11 days (range 1 to 85 days) and a mean weight of 3.2 +/- 0.8 kg, underwent aortic arch reconstruction with LFCP. Seven had biventricular repairs with arch reconstruction, 9 underwent the Norwood operation and 2 had isolated arch repairs. In 1 Norwood and 7 biventricular repair patients, LFCP was maintained by advancing the cannula from the distal ascending aorta into the innominate artery. In 8 of 9 Norwood patients, LFCP was maintained by directing the arterial cannula into the pulmonary artery confluence and perfusing the innominate artery through the right modified Blalock-Taussig shunt fully constructed before cannulation for cardiopulmonary bypass. In 2 patients requiring isolated arch reconstruction, the ascending aorta was cannulated and the cross-clamp was applied just distal to the innominate artery. RESULTS: LFCP was maintained at 0.6 +/- 0.2 L x min(-1) x m(-2) for 41.0 +/- 13.9 minutes at 18.5 degrees C +/- 1.1 degrees C. In 10 of the 18 patients, blood pressure during LFCP was 15 +/- 8 mm Hg remote from the innominate artery (left radial, umbilical or femoral arteries). In 8 of the 18 patients, right radial pressure during LFCP was 24 +/- 10 mm Hg. The mean mixed-venous saturation was 79.8% +/- 10% during LFCP. Two patients had preoperative seizures, whereas none had seizures postoperatively. One patient died. CONCLUSIONS: Neonatal aortic arch reconstruction is possible without circulatory arrest or direct arch vessel cannulation. These techniques maintained adequate mixed-venous oxygen saturations with no associated adverse neurologic outcomes.

Aorta, Thoracic↗
PubMed2001

Systemic steroid pretreatment improves cerebral protection after circulatory arrest.

BACKGROUND: This study evaluates whether systemic steroid pretreatment enhances neuroprotection during deep hypothermic circulatory arrest (DHCA) compared with steroid in cardiopulmonary bypass (CPB) prime. METHODS: Four-week-old piglets randomly placed into two groups (n = 5 per group) were given methylprednisolone (30 mg/kg) into the pump prime (group PP), or pretreated intravenously 4 hours before CPB (group PT). All animals underwent 100 minutes of DHCA (15 degrees C), were weaned off CPB, and were sacrificed 6 hours later. Postoperative changes in body weight, bioimpedance, and colloid oncotic pressure (COP) were measured. Cerebral trypan blue content, immunohistochemical evaluation of transforming growth factor-beta1 (TGF-beta1) expression, and caspase-3 activity were performed. RESULTS: Percentage weight gain (group PP 25.0% +/- 10.4% versus group PT 12.5% +/- 4.0%; p = 0.036), and percentage decrease in bioimpedance (PP 37.2% +/- 14.5% versus PT 15.6% +/- 7.9%; p = 0.019) were significantly lower, whereas postoperative COP was significantly higher in group PT versus group PP (PT 15.3 +/- 1.8 mm Hg versus PP 11.6 +/- 0.8 mm Hg; p = 0.003). Cerebral trypan blue (ng/g dry tissue) was significantly lower in group PT (PT 5.6 x 10(-3) +/- 1.1 x 10(-3) versus PP 9.1 x 10(-3) +/- 5.7 x 10(-4); p = 0.001). Increased TGF-beta1 expression and decreased caspase-3 activity were shown in group PT. CONCLUSIONS: Systemic steroid pretreatment significantly reduced total body edema and cerebral vascular leak and was associated with better immunohistochemical indices of neuroprotection after DHCA.

Animals↗
PubMed2001

Surgical technique to avoid circulatory arrest and direct arch vessel cannulation during neonatal aortic arch reconstruction.

Deep hypothermic circulatory arrest (DHCA) has been used routinely for surgery involving the aortic arch. Recently, techniques have been developed that avoid circulatory arrest and maintain low-flow cerebral perfusion (LFCP) in an attempt to avoid the potential neurological sequelae associated with DHCA. We describe a technique of LFCP that avoids circulatory arrest and direct cannulation of the arch vessels. Five patients underwent reconstruction of the aortic arch with concomitant biventricular intracardiac repair. The distal ascending aorta was cannulated and patients were systemically cooled. The cannula was advanced into the innominate artery and snared in place prior to opening and reconstructing the aorta with continuous LFCP. In all five patients, we completely avoided circulatory arrest and direct cannulation of the arch vessels. All patients survived and there were no adverse neurological outcomes.

Aorta, Thoracic↗
PubMed2001

Single ventricle with systemic obstruction in early life: comparison of initial pulmonary artery banding versus the Norwood operation.

OBJECTIVES: The outcomes of initial pulmonary artery banding (PAB)+/-coarctation repair are compared with the Norwood operation in newborns with single ventricle (SV) and systemic obstruction (SO). METHODS: Between January 1987 and July 2000, 22 patients (median age, 12 days) with SV and aortic arch obstruction (AAO), subaortic stenosis (SAS), or both underwent surgery. Two initial surgical approaches were used: PAB+/-coarctation repair (group I, seven patients); Norwood type operation (group II, 15 patients). RESULTS: The overall mortality was 32% (seven of 22 patients). There was no late mortality. The mortality in group I was 43% versus 27% in group II. Recently, there has been no mortality following the Norwood operation in the last eight patients operated since 1995. Of the survivors, nine patients have undergone the Fontan operation and four patients have had the bidirectional Glenn (BDG) with no deaths. There was one repair of supravalvar aortic stenosis at the time of BDG in group II as opposed to eight reinterventions for SAS and/or AAO in four patients in group I (P=0.01). CONCLUSIONS: PAB+/-coarctation repair for SV and SO is associated with a high mortality and a high reoperation rate for SAS or recurrent AAO. Although the Norwood operation was also associated with a high mortality early on, it can now be performed with excellent outcome. This improvement, combined with a low reintervention rate for SAS or AAO, suggests that the Norwood operation is likely to emerge as the procedure of choice for SV and SO.

Aortic Coarctation↗
PubMed2001

The coronary delivery of marrow stromal cells for myocardial regeneration: pathophysiologic and therapeutic implications.

OBJECTIVES: Bone marrow stromal cells contain "adult stem cells." We tested the hypothesis that coronary-infused bone marrow stromal cells may populate the infarcted heart and undergo milieu-dependent differentiation to regenerate functional tissues with different phenotypic features. METHODS: Isogenic adult rats were used as donors and recipients to simulate autologous transplantation clinically. Myocardial infarction was created by proximal occlusion of left coronary artery in 12 recipient rats. Isolated bone marrow stromal cells were purified, expanded, and retrovirally transduced with LacZ reporter gene for cell labeling. Stromal cells were then infused into the briefly distally clamped ascending aorta of recipient rats 2 weeks after left coronary artery ligation. The hearts were harvested immediately (n = 2) or 4 weeks (n = 10) later to trace the implanted cells and identify their phenotypes. RESULTS: Viable cells labeled with LacZ reporter gene were identified in 8 recipient hearts. Immediately after cell infusion, the labeled cells were trapped within the coronary capillaries. After 4 weeks, they could be detected individually or in clusters within myocardial scar expressing fibroblastic phenotype or outside the infarction area with morphologic features of normal cardiomyocytes. Some were incorporated into endocardium and capillary endothelium. CONCLUSIONS: Our findings suggest that bone marrow stromal cells can traffic through the coronary system to the injured heart and form cardiomyocytes or fibroblasts, depending on the specific microenvironment. Endothelial progenitor cells in the stromal cell population may be involved in the postinfarction neovascularization process. Whether therapeutic use of bone marrow stromal cells can improve the myocardial healing and remodeling process after infarction is worthy of further investigation.

Animals↗
PubMed2000

Norwood operation without circulatory arrest: a new surgical technique.

Circulatory arrest (CA) is associated with potential neurologic injury. We have developed a new surgical technique to eliminate CA during the Norwood operation. A modified Blalock-Taussig shunt (BTS) was fully constructed before cannulation for cardiopulmonary bypass. The aortic cannula was inserted in the patent ductus arteriosus to allow systemic cold perfusion. When deep hypothermia was reached, the aortic cannula was redirected into the pulmonary artery (PA) confluence. Both cerebral and systemic perfusion were maintained through the right PA and BTS into the innominate artery.

Cardiac Surgical Procedures↗
PubMed2000

Utility of near-infrared spectroscopic measurements during deep hypothermic circulatory arrest.

BACKGROUND: Near-infrared spectroscopy (NIRS) is used to monitor cerebral oxygenation during cardiac surgery. However, interpretation of the signals is controversial. The aim of the study was to determine which NIRS variable best correlated with brain damage as assessed by animal behavior and neurohistologic score and to compare the accuracy of NIRS and magnetic resonance spectroscopy (MRS) in predicting brain injury. METHODS: Forty 5-week-old piglets underwent 60 minutes of deep hypothermic circulatory arrest (DHCA) at 15 degrees C. Changes in brain adenosine triphosphate (ATP), phosphocreatine (PCr), and intracellular pH (pHi) were determined by MRS and correlated to changes in oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), and oxidized cytochrome a,a3 (CytOx) NIRS signals. Brains were fixed on day 4 and examined using a neurohistologic score. RESULTS: Reductions in CytOx and HbO2 values were correlated closely with decreases in ATP, PCr, and pHi. The changes in CytOx and PCr showed the strongest correlation (r = 0.623). Maximal CytOx reduction during DHCA of more than -25 microM * differential pathlength factor (DPF) predicted brain damage with a sensitivity of 100% and a specificity of 75%. The histologic score was also correlated with a decrease in ATP (r = -0.52 for CytOx; r = -0.32 for ATP); HbO2, PCr, and pHi showed no correlations. CONCLUSIONS: Reduction in CytOx correlates with decreased brain energy state and predicts histologic brain injury after DHCA with a high sensitivity. These data suggest that the level of CytOx could be a very important predictor of brain damage during DHCA.

Adenosine Triphosphate↗
PubMed2000

Primary repair minimizing the use of conduits in neonates and infants with tetralogy or double-outlet right ventricle and anomalous coronary arteries.

OBJECTIVE: The purpose of this study was to review our results with an approach of early primary repair for tetralogy of Fallot or double-outlet right ventricle with anomalous coronary arteries, using several techniques to minimize the use of a conduit. METHODS: Twenty consecutive neonates and infants with anomalous coronary arteries crossing an obstructed right ventricular outflow tract underwent primary repair. Median age was 5.5 months and mean weight 6.22 kg. The anomalous coronary arteries included the left anterior descending from the right coronary artery (n = 10), the right coronary artery from the left anterior descending (n = 1), the left anterior descending from the right sinus (n = 1), and a significant conal branch from the right coronary artery (n = 7) or left anterior descending (n = 1). Two neonates had pulmonary atresia. The right ventricular outflow tract was reconstructed without a conduit in 18 patients, including those with pulmonary atresia. Surgical techniques included main pulmonary artery translocation in 4 patients, transannular repair under a mobilized left anterior descending coronary artery in 2 patients, and displaced ventriculotomy with subcoronary suture lines in 8 patients. In 4 patients the right ventricular outflow tract was repaired via the ventriculotomy and/or pulmonary arteriotomy. A homograft was used as the sole right ventricle-pulmonary artery connection in 1 patient and in another a homograft was added to a hypoplastic native pathway. RESULTS: There have been no early or late deaths. The right ventricular/left ventricular pressure ratio within 48 hours of the operation was 0.47 +/- 0.10. There were 2 reoperations at 8 and 11 years after the operation, during a mean follow-up of 5.2 years (1-11.3 years). CONCLUSIONS: Primary repair of tetralogy of Fallot or double-outlet right ventricle with anomalous coronary arteries can be done in neonates and infants with excellent results. Alternative surgical techniques for right ventricular outflow tract reconstruction, such as main pulmonary artery translocation, can avoid the use of a conduit in most patients.

Angiography↗
PubMed2000

Cardiac performance after deep hypothermic circulatory arrest in chronically cyanotic neonatal lambs.

OBJECTIVES: It is controversial whether immature cyanotic hearts are more susceptible to ischemic injury than normoxemic hearts. Acutely induced alveolar hypoxic stress before cardiopulmonary bypass has been used as a model of cyanosis and is reported to worsen recovery of immature hearts after subsequent ischemic insult by means of a free radical injury mechanism. Because of concerns about the relevance of acute alveolar repair to the chronic cyanosis encountered clinically, we assessed the effects of chronic cyanosis without alveolar hypoxia, acute alveolar hypoxia, and normoxemia on recovery of cardiac function after deep hypothermic circulatory arrest. METHODS: A chronic cyanosis model was created in 8 lambs by an anastomosis between the pulmonary artery and the left atrium (cyanosis group). Eight lambs underwent sham operation (control). One week later, the animals underwent cardiopulmonary bypass with 90 minutes of deep hypothermic circulatory arrest at 18 degrees C. Another 8 lambs underwent 45 minutes of hypoxic ventilation before bypass, with arterial oxygen tension being maintained at 30 mm Hg (acute hypoxia group). Cardiac index, preload recruitable stroke work, and tau were measured. Malondialdehyde and nitrate-nitrite, nitric oxide metabolites, were also measured in the coronary sinus. Myocardial antioxidant reserve capacity at 2 hours of reperfusion was assessed by measuring lipid peroxidation in left ventricular tissue samples incubated with t-butylhydroperoxide at 37 degrees C. RESULTS: Oxygen tension was 35 +/- 3 mm Hg in the acute hypoxia group versus 93 +/- 7 mm Hg in the control group. In the acute hypoxia group the recovery of cardiac index, preload recruitable stroke work, and tau were significantly worse than that found in both the control and cyanosis groups. Preload recruitable stroke work at 2 hours of reperfusion was slightly but significantly lower in the cyanosis group than in the control group. The postischemic level of nitric oxide metabolites was significantly lower in the acute hypoxia group than in the cyanosis and control groups. However, malondialdehyde levels in the coronary sinus and myocardial antioxidant reserve capacity were not significantly different among the groups. CONCLUSION: Recovery of left ventricular function after deep hypothermic circulatory arrest in neonatal lambs with chronic cyanosis was slightly worse than that found in acyanotic animals. Acute hypoxia before bypass was associated with significantly worse recovery of left ventricular function, and the mechanism of injury may be related to an impairment of nitric oxide production. Free radical injury does not appear to explain any differences among cyanotic, acyanotic, and acutely hypoxic animals in recovery of left ventricular function after ischemia.

Analysis of Variance↗
PubMed2000

Marrow stromal cells for cellular cardiomyoplasty: feasibility and potential clinical advantages.

OBJECTIVES: Marrow stromal cells are mesenchymal stem cells able to differentiate into cardiomyocytes in vitro. We tested the hypothesis that marrow stromal cells, when implanted into myocardium, can undergo milieu-dependent differentiation and express cardiomyogenic phenotypes in vivo. METHODS: Isogenic adult rats were used as donors and recipients to simulate autologous transplantation. Marrow stromal cells isolated from donor leg bones were culture-expanded, labeled with 4;,6-diamidino-2-phenylindole, and then injected into the myocardium of the recipients. The hearts were harvested from 4 days to 12 weeks after implantation, and the implant sites were examined to identify the phenotypes of the labeled marrow stromal cells. RESULTS: Viable cells labeled with 4;, 6-diamidino-2-phenylindole can be identified in host myocardium at all time points after implantation. Implanted marrow stromal cells show the growth potential in a myocardial environment. After 4 weeks, donor cells derived from marrow stromal cells demonstrate myogenic differentiation with the expression of sarcomeric myosin heavy chain and organized contractile proteins. Positive staining for connexin 43 indicates the formation of gap junctions, which suggests that cells derived from marrow stromal cells, as well as native cardiomyocytes, are connected by intercalated disks. CONCLUSIONS: Different cell sources have been used as donor cells for cellular cardiomyoplasty. Our findings indicate that marrow stromal cells can also be used as donor cells. In an appropriate microenvironment they will exhibit cardiomyogenic phenotypes and may replace native cardiomyocytes lost by necrosis or apoptosis. Because marrow stromal cells can be obtained repeatedly by bone marrow aspiration and expanded vastly in vitro before being implanted or used as autologous implants, and because their use does not call for immunosuppression, the clinical use of marrow stromal cells for cellular cardiomyoplasty appears to be most advantageous.

Animals↗
PubMed1999

Effects of cyanosis and hypothermic circulatory arrest on lung function in neonatal lambs.

BACKGROUND: Lung function is often impaired after cardiac surgery and cardiopulmonary bypass (CPB), particularly in chronically cyanotic patients. This study aimed to evaluate lung function in a surgically created chronic cyanotic neonatal lamb model after CPB and deep hypothermic circulatory arrest (DHCA) and to assess the role of nitric oxide (NO) in the pathogenesis of increased pulmonary vascular resistance. METHODS: A chronic cyanosis model was surgically created in 7 lambs (4.7+/-0.8 days old) by anastomosing the pulmonary artery (PA) to the left atrium (LA). Another 7 lambs underwent a sham operation (control). One week later, the animals underwent shunt takedown and CPB with 90 minutes of DHCA at 18 degrees C. Cardiac index (CI), pulmonary vascular resistance index (PVRI), lung dynamic compliance (Cdyn), alveolar-arterial oxygen difference (AaDO2), left atrial plasma nitrate/nitrite (NO metabolites) levels, and pulmonary cGMP production (concentration difference between LA and PA) were measured before CPB and at 1 and 2 hours after reperfusion. RESULTS: The cyanosis model consistently produced significantly lower arterial oxygen tension (34.8+/-2.3 vs 93.1+/-8.8 torr in control, p < 0.001) and Qp/Qs (0.6+/-0.1 vs 1.0+/-0.0 in control, p < 0.001) than controls. Postoperative PVRI was significantly lower in the cyanosis group than in controls, although CPB with DHCA significantly elevated PVR in both cyanotic and control animals. There were no significant differences in AaDO2 and Cdyn after CPB between groups. The level of NO metabolites did not change before or after CPB in either cyanotic or acyanotic animals. NO metabolite levels tended to be higher in the cyanotic animals (p = 0.08). There was no significant difference in pulmonary cGMP production between both groups. CONCLUSIONS: These findings suggest that CPB with DHCA, per se, does not affect NO production in cyanotic or acyanotic neonatal lambs but causes increased PVR in both groups. Chronic cyanosis does not result in reduced pulmonary function after CPB with DHCA, and is associated with lower PVR. The mechanism may involve an increased NO production in cyanotic animals.

Animals↗
PubMed1999

Hemolytic anemia after atrioventricular septal defect repair without synthetic material.

We report a rare case of severe hemolytic anemia following repair of a congenital heart defect without the use of prosthetic material. A review of the literature, diagnosis, and management are described. Although this is an unusual complication following congenital heart surgery, a high index of suspicion must be maintained and a possible mechanical cause should be sought and corrected.

Anemia, Hemolytic↗
PubMed1999

Tissue engineering of autologous aorta using a new biodegradable polymer.

BACKGROUND: Ovine pulmonary valve leaflets and pulmonary arteries have been tissue-engineered (TE) from autologous cells and biodegradable polyglycolic acid (PGA)-polyglactin copolymers. Use of this cell-polymer construct in the systemic circulation resulted in aneurysm formation. This study evaluates a TE vascular graft in the systemic circulation which is based on a new copolymer of PGA and polyhydroxyalkanoate (PHA). METHODS: Ovine carotid arteries were harvested, expanded in vitro, and seeded onto 7-mm diameter PHA-PGA tubular scaffolds. The autologous cell-polymer vascular constructs were used to replace 3-4 cm abdominal aortic segments in lambs (group TE, n = 7). In a control group (n = 4), aortic segments were replaced with acellular polymer tubes. Vascular patency was evaluated with echography. All control animals were sacrificed when the grafts became occluded. Animals in TE group were sacrificed at 10 days (n = 1), 3 (n = 3), and 5 months (n = 3). Explanted TE conduits were evaluated for collagen content, deoxyribonucleic acid (DNA) content, structural and ultrastructural examination, mechanical strength, and matrix metalloproteinase (MMP) activity. RESULTS: The 4 control conduits became occluded at 1, 2, 55, and 101 days. All TE grafts remained patent, and no aneurysms developed by the time of sacrifice. There was one mild stenosis at the anastomotic site after 5 months postoperatively. The percent collagen and DNA contents approached the native aorta over time (% collagen = 25.7%+/-3.4 [3 months] vs 99.6%+/-11.7 [5 months], p < 0.05; and % DNA = 30.8%+/-6.0 [3 months] vs 150.5%+/-16.9 [5 months], p < 0.05). Histology demonstrated elastic fibers in the medial layer and endothelial specific von Willebrand factor on the luminal surface. The mechanical strain-stress curve of the TE aorta approached that of the native vessel. A 66 kDa MMP-2 was found in the TE and native aorta but not in control group. CONCLUSIONS: Autologous aortic grafts with biological characteristics resembling the native aorta can be created using TE approach. This may allow the development of "live" vascular grafts.

Animals↗
PubMed1999

A novel sialyl Lewis X analog attenuates cerebral injury after deep hypothermic circulatory arrest.

BACKGROUND: The initial step in the inflammatory process, which can be initiated by cardiopulmonary bypass and by ischemia/reperfusion, is mediated by interactions between selectins on endothelial cells and on neutrophils. We studied the effects of selectin blockade using a novel Sialyl Lewis X analog (CY-1503) on recovery after deep hypothermic circulatory arrest in a piglet model. METHODS: Twelve Yorkshire piglets were subjected to cardiopulmonary bypass, 30 minutes of cooling, 100 minutes of circulatory arrest at 15 degrees C, and 40 minutes of rewarming. Five animals received a bolus of 60 mg/kg of CY-1503 and an infusion (3 mg/kg per hour) for 24 hours from reperfusion (group O), and 7 randomly selected control piglets received saline solution (group C). Body weight and total body water content were evaluated 3 hours and 24 hours after reperfusion by a bio-impedance technique. Neurologic recovery of animals was evaluated daily by neurologic deficit score (0 = normal, 500 = brain death) and overall performance categories (1 = normal, 5 = brain death). The brain was fixed in situ on the fourth postoperative day and examined by histologic score (0 = normal, 5+ = necrosis) in a blinded fashion. RESULTS: Two of 7 animals in group C died. The neurologic deficit score was significantly lower in group O than in group C (postoperative day 1, P <.001; postoperative day 2, P =.02). The overall performance category was significantly lower in group O than in group C on postoperative day 2 (P =.01). Percentage total body water after cardiopulmonary bypass was significantly higher in group C than in group O (P =.03). Histologic score tended to be higher in group C than in group O, but this difference did not reach statistical significance (group O = 0.5 +/- 0.7; group C = 1.3 +/- 1.off CONCLUSION: Blockade of selectin adhesion molecules by saturation with a Sialyl Lewisx analog accelerates recovery after 100 minutes of deep hypothermic circulatory arrest in a piglet survival model.

Animals↗
PubMed1999

Transplantation versus coronary artery bypass in patients with severe ventricular dysfunction. Surgical outcome and quality of life.

BACKGROUND: The purpose of this study is to evaluate the quality of life, functional status and survival rate of patients with left ventricular ejection fraction (LVEF) < or = 20% following coronary bypass (CABG) versus heart transplantation. METHODS EXPERIMENTAL DESIGN: comparative study, mean follow-up of 20 months. SETTING: division of cardiac surgery at a McGill University-based hospital in Montreal, Canada. PATIENTS: the charts of 65 consecutive patients with angiographic LVEF < or = 20% were reviewed. Among these patients, 14/65 were referred for transplantation but instead underwent CABG (Group I) after consultation with the transplant committee. The charts of 14 matched transplant patients (Group II) were reviewed. The SF-36 and Duke's questionnaire forms were mailed to both groups in order to evaluate their quality of life and functional capacity, respectively. INTERVENTIONS: comparison between coronary bypass and heart transplantation. MEASURES: main outcome measures were mortality, quality of life, and functional capacity. RESULTS: Results are expressed as mean+/-SEM. The in-hospital mortality rate of CABG among all patients with LVEF < or = 20% was 4.6% (3/65). Among the 14 CABG patients initially referred for transplantation, perioperative mortality was 1/14 (7.1%), same as in the matched transplant group. Three additional group I patients were reported by family to have died of cardiac events at follow-up period. Postoperative death identified at follow-up was assigned the lowest life quality score. The transformed quality of life scores were as follows: physical functioning: I=42.5+/-10.6, II=73.2+/-7.2, p=0.029; physical role: I=35.0+/-13.5, I=61.4+/-13.2, p=0.180; bodily pain: I=54.0+/-14.0, II=69.8+/-8.5, p=0.349; general health: I=34.7+/-9.2, II=84.6+/-5.2, p=0.0003; vitality: I=36.5+/-9.3, II=60.0+/-5.2, p=0.045; social functioning: I=55.0+/-4.0, II=87.5+/-5.1, p=0.050; emotional role: I=36.7+/-15.3, II=87.9+/-6.8, p=0.009; mental health: I=52.8+/-12.4, II=81.5+/-4.2, p=0.054. Duke's activity status index: I=16.8+/-4.2, II=31.8+/-4.2, p=0.021. CONCLUSIONS: Heart transplant is associated with a significantly superior postoperative quality of life and functional capacity than bypass surgery. However, in patients with LVEF < or = 20%, CABG can be performed with an acceptable perioperative mortality of 4.6%-7.1%, similar to the rate for transplantation.

Activities of Daily Living↗
PubMed1998

High-volume continuous hemofiltration during cardiopulmonary bypass attenuates pulmonary dysfunction in neonatal lambs after deep hypothermic circulatory arrest.

BACKGROUND: Cardiopulmonary bypass (CPB) induces an inflammatory reaction that activates neutrophils and releases free radicals in tissue. Ischemia-reperfusion further aggravates inflammation. Hemofiltration (HF) could potentially remove inflammatory mediators and reduce injury. This study assessed the effect of continuous high-volume HF during CPB on systemic edema formation and pulmonary function after deep hypothermic circulatory arrest (DHCA). METHODS AND RESULTS: Anesthetized lambs (n = 16) underwent CPB with systemic cooling (40 minutes), DHCA (120 minutes at 18 degrees C), and rewarming (40 minutes). All animals were weaned from CPB and observed for 3 hours after reperfusion. Continuous HF was used in 8 lambs at a flow rate of 300 mL/kg per hour throughout CPB, simultaneously replacing hemofiltration volume with a balanced salt solution (HF group). In 8 control animals, no hemofiltration was performed. Hematocrit remained at 23% to 25% during the experiment in both groups. Pulmonary vascular resistance (PVR), lung dynamic compliance (Cdyn), alveolar-arterial oxygen difference (AaDO2), and total body water content (bioimpedance) were measured. Malondialdehyde (MDA), a product of lipid peroxidation, was assayed in lung tissue. Percent increase of body water content at 180 minutes of reperfusion was significantly lower in the HF group than in control (132 +/- 2% vs 152 +/- 5%, P < 0.005). There was less of a rise in PVR compared with baseline at 180 minutes of reperfusion in the HF group than in control (131 +/- 8% vs 238 +/- 26%, P < 0.005). In addition, percent recovery of Cdyn and AaDO2 in the HF group was preserved significantly (respectively, P < 0.05) 2 hours after reperfusion than in the control group. Lung tissue MDA in the HF group (46.2 +/- 12.6 vs 65.3 +/- 17.1 nmol/L per gram of tissue, P < 0.05) was significantly lower than in the control group. CONCLUSIONS: High-volume, continuous hemofiltration during CPB attenuates systemic edema formation, pulmonary hypertension, the extent of lung dysfunction, and depression of cardiac output and reduces free radical-mediated tissue injury after CPB with DHCA. This technique may have a clinical application to reduce the morbidity rate of CPB.

Animals↗