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Biomedical subjects

J E Mayer

Publications and source records attributed to J E Mayer.

At least 55 records · Page 3Linked to original sources
PubMed2000

Fabrication of a trileaflet heart valve scaffold from a polyhydroxyalkanoate biopolyester for use in tissue engineering.

Previously, we reported the implantation of a single tissue engineered leaflet in the posterior position of the pulmonary valve in a lamb model. The major problems with this leaflet replacement were the scaffold's inherent stiffness, thickness, and nonpliability. We have now created a scaffold for a trileaflet heart valve using a thermoplastic polyester. In this experiment, we show the suitability of this material in the production of a biodegradable, biocompatible scaffold for tissue engineered heart valves. A heart valve scaffold was constructed from a thermoplastic elastomer. The elastomer belongs to a class of biodegradable, biocompatible polyesters known as polyhydroxyalkanoates (PHAs) and is produced by fermentation (Metabolix Inc., Cambridge, MA). It was modified by a salt leaching technique to create a porous, three-dimensional structure, suitable for tissue engineering. The trileaflet heart valve scaffold consisted of a cylindrical stent (1 mm X 15 mm X 20 mm I.D.) containing three valve leaflets. The leaflets were formed from a single piece of PHA (0.3 mm thick), and were attached to the outside of the stent by thermal processing techniques, which required no suturing. After fabrication, the heart valve construct was allowed to crystallize (4 degrees C for 24 h), and salt particles were leached into doubly distilled water over a period of 5 days to yield pore sizes ranging from 80 to 200 microns. Ten heart valve scaffolds were fabricated and seeded with vascular cells from an ovine carotid artery. After 4 days of incubation, the constructs were examined by scanning electron microscopy. The heart valve scaffold was tested in a pulsatile flow bioreactor and it was noted that the leaflets opened and closed. Cells attached to the polymer and formed a confluent layer after incubation. One advantage of this material is the ability to mold a complete trileaflet heart valve scaffold without the need for suturing leaflets to the conduit. Second advantage is the use of only one polymer material (PHA) as opposed to hybridized polymer scaffolds. Furthermore, the mechanical properties of PHA, such as elasticity and mechanical strength, exceed those of the previously utilized material. This experiment shows that PHAs can be used to fabricate a three-dimensional, biodegradable heart valve scaffold.

Animals↗
PubMed2000

New pulsatile bioreactor for in vitro formation of tissue engineered heart valves.

Two potential obstacles to the creation of implantable tissue engineered heart valves are inadequate mechanical properties (ability to withstand hemodynamic stresses) and adverse host-tissue reactions due to the presence of residual nondegraded polymer scaffold. In an attempt to address these problems, we developed an in vitro cell culture system that provides physiological pressure and flow of nutrient medium to the developing valve constructs. It is anticipated that in vitro physical stress will stimulate the tissue engineered heart valve construct to develop adequate strength prior to a possible implantation. Long-term in vitro development will be realized by an isolated and thereby contamination-resistant system. Longer in vitro development will potentially enable more complete biodegradation of the polymeric scaffold during in vitro cultivation. This new dynamic bioreactor allows for adjustable pulsatile flow and varying levels of pressure. The system is compact and easily fits into a standard cell incubator, representing a highly isolated dynamic cell culture setting with maximum sterility, optimal gas supply and stable temperature conditions especially suited for long-term experiments.

Animals↗
PubMed1999

Repair of tetralogy of Fallot in neonates and young infants.

BACKGROUND: The timing of repair of tetralogy of Fallot (TOF) remains controversial. Advantages to early complete repair include removal of right ventricular outflow tract obstruction, alleviation of systemic hypoxia, and avoidance of palliation with an arteriopulmonary shunt. METHODS AND RESULTS: This is a retrospective review of 99 children with TOF pulmonary stenosis (TOF/PS) or TOF pulmonary atresia (TOF/PA) who were <90 days of age undergoing early complete repair. Fifty-nine were prostaglandin E dependent, and 91% of neonates were symptomatic at the time of repair. Univariate and multivariate analyses of patient characteristics, anatomic features, and operative management showed the diagnosis of TOF/PA and smaller body surface area to be the only independent risk factors for death. Early mortality was 3% (3 of 99), and actuarial survival rates were 94% at 1 year and 91.6% at 5 years. Freedom from catheterization was 86% at 1 year and 73% at 5 years. Patients repaired for TOF/PA had a significantly lower freedom from reoperation than did those repaired for TOF/PS. CONCLUSIONS: Early complete TOF repair can be accomplished with a low mortality. Children with TOF/PA repaired had a lower freedom from reoperation that did those with TOF/PS. Longer follow-up, with emphasis on arrhythmias and right ventricular function, is required to define the long-term benefits of early repair.

Cardiac Surgical Procedures↗
PubMed1999

Left ventricular assist device improves survival in children with left ventricular dysfunction after repair of anomalous origin of the left coronary artery from the pulmonary artery.

BACKGROUND: Repair of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) in infants carries a high operative risk, particularly in infants with myocardial infarction and poor left ventricular function. The marked recovery of left ventricular function reported late after repair, however, suggests that an aggressive approach to repair should be undertaken. METHODS: Of 31 children undergoing primary repair of ALCAPA at our institution from 1987 to 1996, 26 were infants (6 weeks to 9 months old). All but 2 had severe left ventricular dysfunction, and 8 had moderate to severe mitral regurgitation. Seven children were unable to be weaned from cardiopulmonary bypass because of poor left ventricular function and elevated left atrial pressure. These 7 children were placed on mechanical left ventricular support using a centrifugal pump, with support ranging from 2.2 to 70.6 hours. RESULTS: One child died shortly after the start of left ventricular assist (2.2 hours), and another died of arrhythmia within 24 hours after successful decannulation. All 5 survivors had significant improvement in left ventricular function, with 2 requiring late mitral valve repair. CONCLUSIONS: Infants with ALCAPA who have severe left ventricular dysfunction represent a higher risk group for repair. However, with use of mechanical circulatory support in those unable to be weaned from cardiopulmonary bypass, a high survival rate can be achieved with good long-term recovery. We conclude that an aggressive approach to early repair in all children with ALCAPA is warranted, regardless of the degree of left ventricular dysfunction.

Cardiopulmonary Bypass↗
PubMed1999

Valved homograft conduit repair of the right heart in early infancy.

BACKGROUND: Valved homograft conduit repair in neonates and young infants creates a physiologically normal biventricular circulation, and unlike shunts, avoids surgery on the branch pulmonary. METHODS: Retrospective chart review was used for 84 patients operated on between 1990 and 1995 (mean age 26+/-28 days, mean weight 3.3+/-0.8 kg) undergoing homograft conduit repair in the first 3 months of life. Cases were divided into simple and complex, eg, absent pulmonary valve syndrome or associated interrupted arch. Mean homograft size was 9.0+/-2 mm. RESULTS: Early mortality was 4.7% (simple) and 30% (complex). Mean hospital stay was 18 days. Mean follow-up was 34 months. Thirty-seven (47%) patients underwent conduit replacement. Median time to reoperation was 3.1 years. Mean size of replacement homograft was 17+/-2 mm. There were no deaths at reoperation. Mean hospital stay at conduit change was 6.3 days. Probability of survival at 5 years is 75%. CONCLUSIONS: Biventricular repair employing a conduit can be performed safely in noncomplex anomalies in the first 3 months of life. Time interval until repeat surgery is relatively short but equal or greater than that with most palliative procedures.

Bioprosthesis↗
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

Pediatric lung transplantation and "lessons from Green Surgery.".

During the past decade, lung transplantation has emerged as the definitive treatment for children with end-stage lung disease. Pediatric transplantation presents unique challenges with respect to diagnostic indications, donor-recipient size disparities, perioperative management, and growth. Lessons from the early development of cardiac surgery at the University of Minnesota (Green Surgical Service) provide a useful model for novel surgical challenges. Since 1990, 25 lung transplantations have been performed at our institution, including 4 heart-lung, 3 single-lung, 17 bilateral-lung, and 1 living-related lobar allograft. Age at transplantation ranged from 7 months to 27 years. The most common indication was cystic fibrosis. Given the limited donor pool, size disparities between donor and recipient were frequent. Excessive donor size was addressed by parenchymal reduction. Accommodation of small donor allografts was facilitated by elective cardiopulmonary bypass and pulmonary vasodilation using inhaled nitric oxide. Epidural anesthesia was routinely used for postoperative pain management and to enhance good pulmonary hygiene. Immunosuppression is presently achieved using cyclosporine, mycophenolate mofetil, and corticosteroids. Monitoring for rejection is accomplished with spirometry and transbronchial biopsies. Bronchial complications in 2 patients required placement of Palmaz stents. The living-related allograft was performed in a previous bone marrow transplant recipient obviating the need for long-term immunosuppression. The potential for growth of mature lung parenchyma postoperatively was studied and verified in a sheep model. Our experience parallels that of other frontiers such as early cardiac surgery in which medical and technologic innovations can be applied in a supportive environment to permit surgical progress.

Adolescent↗
PubMed1999

Myocardial self-preservative effect of heat shock protein 70 on an immature lamb heart.

BACKGROUND: Heat shock proteins have been shown to enhance myocardial tolerance of ischemia-reperfusion injury and are induced in the myocardium of many animals by various stressors. METHODS: To assess the effects and time course of the inducible form of heat shock protein 70, we raised the rectal temperature of 15 neonatal lambs to 43 degrees C for 15 minutes. At 15, 30, 60, and 120 minutes and 24 hours after heat shock, hearts were subjected to immunoblot analysis for heat shock protein (hsp 72/73). Twenty-four hours after heat shock, neonatal lamb hearts (n = 8) were subjected to 2 hours of cold cardioplegic ischemia (HSP group). Eight neonatal lamb hearts without heat shock served as control. After 60 minutes of reperfusion, left ventricular systolic and diastolic function, coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and lactate levels were measured. Endothelial function was assessed by measuring in situ coronary vascular resistance response to acetylcholine and trinitroglycerine. RESULTS: The HSP group showed a significantly higher recovery of systolic function as well as MVO, and a lower lactate level compared to the control group at 60 minutes after reperfusion. Recovery of coronary endothelial function was also significantly better in the HSP group than in the control group. Inducible form of HSP 70 was expressed 15 minutes after heat shock and continued to be observed at 24 hours after the stress. CONCLUSIONS: Heat shock stress associated with the production of inducible heat shock proteins improved the recovery of ventricular function as well as endothelial function and aerobic metabolism after hypothermic cardioplegic ischemia. Induction of heat shock proteins by any means prior to planned hypothermic ischemia may lead to a new approach for myocardial protection.

Animals↗
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

Forty-one years of surgical experience with congenital supravalvular aortic stenosis.

OBJECTIVE: Several techniques for symmetric reconstruction of the aortic root in congenital supravalvular aortic stenosis have been developed, but it remains unclear whether these prove superior to patch enlargement of the noncoronary sinus alone. We reviewed our experience with surgical treatment of supravalvular aortic stenosis and investigated the impact of the surgical technique on long-term results. METHODS AND RESULTS: Seventy-five patients underwent operations to treat congenital supravalvular aortic stenosis at our institution between 1957 and 1998. Surgical procedures included patch enlargement of the noncoronary sinus only (n = 34), inverted bifurcated patch plasty (n = 35), and 3-sinus reconstruction of the aortic root (n = 6). There were 7 early deaths. Among those who survived the operation, 100% were alive at 5 years, 96% were alive at 10 years, and 77% were alive at 20 years. According to time-related analysis diffuse stenosis of the ascending aorta proved a risk factor for both survival and reoperation (P <.01 for each). Patients with multiple-sinus reconstructions of the aortic root accounted for only 2 of the 14 reoperations and none of the late deaths (both P <.001). Residual gradients were lower after multiple-sinus reconstruction of the aortic root (median 10 mm Hg vs 20 mm Hg for patch enlargement of the noncoronary sinus only, P =. 008), as was the prevalence of moderate aortic regurgitation at follow-up (3% vs 22%, P =.05). CONCLUSIONS: Results of operations for supravalvular aortic stenosis improved greatly after the introduction of more symmetric reconstructions of the aortic root. Multiple-sinus reconstructions (inverted bifurcated patch plasty and 3-sinus reconstruction) resulted in superior hemodynamics and were associated with reductions in both mortality rate and need for reoperation.

Aortic Valve Stenosis↗
PubMed1999

Improved results with selective management in pulmonary atresia with intact ventricular septum.

OBJECTIVE: Late outcome of neonatal pulmonary atresia with intact ventricular septum remains poor in most reported series. We have followed a selective approach toward either single ventricle repair versus complete or partial biventricular repair based on the presence of right ventricle-dependent coronary circulation and growth of the right ventricle. METHODS: A retrospective chart review was conducted of 47 patients who underwent surgery between January 1991 and September 1998. RESULTS: Sixteen (34%) patients had a right ventricle-dependent coronary circulation, with a tricuspid valve Z-score of -3.0 +/- 0.66 versus -2.0 +/- 0.95 (P =.002) for those without a right ventricle-dependent coronary circulation. A systemic-pulmonary artery shunt only was performed in all patients with a right ventricle-dependent coronary circulation, with 1 death. Fourteen of 16 patients with a right ventricle-dependent coronary circulation underwent a bidirectional Glenn shunt at a median of 9 months after their first operation, 9 of whom have had a Fontan procedure (no deaths). In the 31 (66%) patients without a right ventricle-dependent coronary circulation, 6 patients underwent only a systemic-pulmonary artery shunt, 23 had a shunt and right ventricular decompression, and 2 had only a transannular patch. In this group, 10 patients received a 2-ventricle repair, 6 a 1. 5-ventricle repair, and 8 patients had a Fontan procedure. There was 1 early death and the overall survival was 98% at 1 year, 5 years, and 7 years. CONCLUSIONS: If patients are stratified well, excellent survival can be achieved in the treatment of pulmonary atresia with intact ventricular septum. This result may be at the price of achieving a 1-ventricle as opposed to a 2-ventricle repair.

Actuarial Analysis↗
PubMed1999

Mechanical circulatory support in children with cardiac disease.

OBJECTIVE: To review the experience from a single center that uses both extracorporeal membrane oxygenation and ventricular assist devices for children with cardiac disease requiring mechanical circulatory support. METHODS: A retrospective chart review was performed for all pediatric patients with cardiac disease who required support with extracorporeal membrane oxygenation or ventricular assist devices. Statistical analysis of the impact of multiple clinical parameters on survival was performed. RESULTS: From 1987 through 1996 we provided mechanical circulatory support for children with a primary cardiac diagnosis using extracorporeal membrane oxygenation (67 patients) and ventricular assist devices (29 patients). Twenty-seven of 67 (40.3%) patients supported with extracorporeal membrane oxygenation and 12 of 29 (41.4%) patients supported with ventricular assist devices survived to hospital discharge. Failure of return of ventricular function within 72 hours of the institution of support was an ominous sign in patients supported with either modality. Univariate analysis revealed the serum pH at 24 hours of support, the serum bicarbonate at 24 hours of support, the urine output over the first 24 hours of support, and the development of renal failure to have a statistically significant association with survival in children supported with extracorporeal membrane oxygenation. None of the clinical parameters evaluated by univariate analysis were significantly associated with survival in the patients supported with ventricular assist devices. CONCLUSIONS: Extracorporeal membrane oxygenation and ventricular assist devices represent complementary modalities of mechanical circulatory support that can both be used effectively in children with cardiac disease.

Child↗
PubMed1999

Evolution of risk factors influencing early mortality of the arterial switch operation.

OBJECTIVES: The present study was undertaken to determine the independent risk factors for early mortality in the current era after arterial switch operation (ASO). BACKGROUND: Prior reports on factors affecting outcome of the ASO demonstrated that abnormal coronary arterial patterns were associated with increased risk of early mortality. As diagnostic, surgical and perioperative management techniques continue to evolve, the risk factors for the ASO may have changed. METHODS: All patients who underwent the ASO at Children's Hospital, Boston between January 1, 1992 and December 31, 1996 were included. Hospital charts, echocardiographic and cardiac catheterization data and operative reports of all patients were reviewed. Demographics and preoperative, intraoperative and postoperative variables were recorded. RESULTS: Of the 223 patients included in the study (median age at ASO = 6 days and median weight = 3.5 kg), 26 patients had aortic arch obstruction or interruption, 12 had Taussig-Bing anomaly, 12 had multiple ventricular septal defects, 8 had right ventricular hypoplasia and 6 were premature. There were 16 early deaths (7%), with 3 deaths in the 109 patients considered "low risk" (2.7%). Coronary artery pattern was not associated with an increased risk of death. Compared with usual coronary anatomy pattern, however, inverted coronary patterns and single right coronary patterns were associated with increased incidence of delayed sternal closure (p = 0.003) and longer duration of mechanical ventilation (p = 0.008). In a multivariate logistic regression model using only preoperative variables, aortic arch repair at a separate procedure before ASO and smaller birth weight were independent predictors of early mortality. In a second model that included both pre- and intraoperative variables, circulatory arrest time and right ventricular hypoplasia were independent predictors of early death. CONCLUSIONS: The ASO can be performed in the current era without excess early mortality related to uncommon coronary artery patterns. Aortic arch repair before ASO, right ventricular hypoplasia, lower birth weight and longer intraoperative support continue to be independent risk factors for early mortality after the ASO.

Abnormalities, Multiple↗
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↗
PubMed1998

Effects of a monoclonal antibody to P-selectin on recovery of neonatal lamb hearts after cold cardioplegic ischemia.

BACKGROUND: The interaction between endothelium and leukocytes plays a crucial role in ischemia-reperfusion injury. P-selectin, which is expressed on activated endothelium, mediates the first step in leukocyte adherence to the endothelium. This study examined the effects of a monoclonal antibody (mAb) against P-selectin on the recovery of cardiac function and myocardial neutrophil infiltration after ischemia. METHODS AND RESULTS: Thirteen blood-perfused, isolated neonatal lamb hearts underwent 2 hours of hypothermic cardioplegic arrest and 2 hours of reperfusion. Immediately before reperfusion, mAb to P-selectin was administered to the perfusate (15 micrograms/mL) in 6 hearts (group P-sel). In control (n = 7), the same volume of saline was added. Isovolumic left ventricular function and coronary blood flow were measured. At 2 hours after reperfusion, myocardial myeloperoxidase activity, an index of neutrophil accumulation, was assayed. At 30 minutes of reperfusion, hearts treated with mAb to P-selectin achieved significantly greater recovery of maximum developed pressure (70 +/- 4% in control versus 77 +/- 2% in group P-sel, P < 0.01), maximum positive first derivative of pressure (dP/dt) (64 +/- 7% in control versus 73 +/- 5% in group P-sel, P < 0.05), and maximum negative dP/dt (61 +/- 6% in control versus 70 +/- 6% in group P-sel, P < 0.05) compared with control. Percent baseline of coronary blood flow was also significantly increased in group P-sel (135 +/- 40% in control versus 205 +/- 43% in group P-sel, P < 0.05). Myocardial myeloperoxidase activity was significantly lower (P < 0.05) in group P-sel (4.7 +/- 3.2) versus control (16.0 +/- 10.1). (Units are change in absorbance/min/g tissue.) CONCLUSIONS: The functional blockade of P-selectin resulted in better recovery of cardiac function and attenuated neutrophil accumulation during early reperfusion. Strategies to block P-selectin mediated neutrophil adherence may have clinical application in improving myocardial function at early reperfusion.

Animals↗
PubMed1998

Duration of complete atrioventricular block after congenital heart disease surgery.

Children with complete heart block following surgery for congenital heart diseases were prospectively followed to assess the timing for recovery of atrioventricular conduction, and to determine if there were clinical variables that reliably predict permanent heart block. Recovery of atrioventricular conduction occurred by postoperative day 9 in 97% of patients with transient heart block.

Cardiac Surgical Procedures↗