Prospective randomized comparison of CarboMedics and St. Jude Medical bileaflet mechanical heart valve prostheses: Ten-year follow-up

OBJECTIVE

This is the final report of a randomized controlled trial comparing the performance of CarboMedics (CarboMedics Inc., Austin, Tex) and St. Jude Medical (St. Jude Medical Inc, St Paul, Minn) bileaflet mechanical heart valve prostheses 10 years after surgery.

METHODS

Between 1992 and 1996, 485 patients undergoing mechanical heart valve replacement were randomized to receive CarboMedics (n = 234) or St. Jude Medical (n = 251) prostheses for aortic (n = 288), mitral (n = 160), or double (n = 37) valve replacements. Patients were followed annually to the end of 2004.

RESULTS

Demographic, preoperative, and operative characteristics were similar between the 2 groups. The median follow-up was 10 years in both groups (CarboMedics 99% complete, St. Jude Medical 98% complete; 3879 patient-years of follow-up). Overall, 165 patients died, 25 of valve-related causes. Ten-year survivals were 66.4% (95% confidence interval: 59.6%-72.3%) and 64.7% (95% confidence interval: 58.0%-70.6%) in the CarboMedics and St. Jude Medical groups, respectively (P = .94). Freedom at 10 years from valve-related mortality was 95.0% (95% confidence interval: 90.8%-97.3%) in the CarboMedics group and 93.0% (95% confidence interval: 88.3%-95.9%) in the St. Jude Medical group. During follow-up, 34 patients had a thromboembolic event, 79 patients had at least 1 bleeding event, and 14 patients required reoperation. There were no significant differences between the groups with respect to freedom from complications (P > or = .12); freedom from thromboembolism at 10 years (CarboMedics: 91.5%, 95% confidence interval: 86.5%-94.7%; St. Jude Medical: 92.2%, 95% confidence interval: 87.5%-95.2%); freedom from bleeding events (CarboMedics: 83.0%, 95% confidence interval: 76.6%-87.8%; St. Jude Medical: 77.5%, 95% confidence interval: 71.1%-82.7%); and freedom from death or valve-related complication (CarboMedics: 51.6%, 95% confidence interval: 44.7%-58.0%; St. Jude Medical: 46.2%, 95% confidence interval: 39.7%-52.4%). Linearized rates per patient-year were 1.1% in the CarboMedics group and 0.8% in the St. Jude Medical group for thromboembolism; 2.3% in the CarboMedics group and 3.2% in the St. Jude Medical group for bleeding events; and 0.72% in the CarboMedics group and 0.47% in the St. Jude Medical group for nonstructural valve dysfunction. International normalized ratio values were similar between the 2 groups throughout the study period.

CONCLUSION

At 10 years, the clinical outcome was similar with respect to these 2 mechanical bileaflet prostheses.

Orally administered penicillamine is a potent inhibitor of neointimal and medial thickening in porcine saphenous vein–carotid artery interposition grafts

OBJECTIVE

In patients who have undergone coronary artery bypass grafting, blood copper levels are elevated for 6 weeks after surgery. Copper is an established risk factor for cardiovascular disease and atherogenesis and promotes oxidative stress, lipid oxidation, cell proliferation, and matrix formation, all components of vein graft disease. This project therefore examined the effect of the copper chelator penicillamine on saphenous vein graft thickening in a pig model.

METHODS

Saphenous vein-carotid artery interposition grafts were carried out in Landrace pigs. Penicillamine (10 mg/kg once daily, n = 8) was administered orally incorporated into small amounts of mashed potato for 1 month (n = 8 controls). Vein grafts were then excised and fixed at 100 mm Hg, histologic sections were prepared, and morphometry and measurement of proliferating cell nuclear antigen count were carried out. In vitro studies on the effect of copper or penicillamine on human vascular smooth muscle cell replication was carried out with bromodeoxyuridine incorporation.

RESULTS

Administration of penicillamine had a potent inhibitory effect on both neointimal and medial thickness and proliferating cell nuclear antigen count but elicited a marked increase in luminal area and reduced serum copper concentrations. In vitro, copper augmented vascular smooth muscle cell proliferation, an effect blocked by penicillamine. Penicillamine alone also inhibited in vitro vascular smooth muscle cell replication.

CONCLUSION

The administration of penicillamine reduces vein graft thickening and promotes positive remodeling through negation of copper-induced cell proliferation. Copper chelators may therefore be therapeutically useful in preventing late vein graft failure in patients undergoing reconstructive arterial surgery.

Indications for Blood Transfusion in Cardiac Surgery

In addition to its life-saving effect in hemorrhagic shock, transfusion of allogenic packed red blood cells can be beneficial in situations where a critically low hematocrit is contributing to a state of oxygen-supply dependency. These benefits are countered by the risks of transfusion-associated lung injury, transfusion-associated immunomodulation, and cellular hypoxia after RBC transfusion. The critical hematocrit is patient and organ specific, and varies intraoperatively according to the duration and temperature of bypass, as well as for a variable postoperative period. Future randomized studies must prospectively evaluate regional indicators of tissue oxygenation in transfusion algorithms.

On the biology of saphenous vein grafts fitted with external synthetic sheaths and stents

Autologous saphenous vein is used as a conduit to bypass atherosclerotic lesions in both the coronary artery (coronary artery bypass graft surgery [CABG]) and in femoral arteries (infrainguinal bypass graft surgery [IIBS]). Despite the undoubted success and benefits of the procedures, graft failure occurs in 50% of cases within 10 years after surgery. A principal cause of late vein graft failure is intimal and medial hyperplasia and superimposed atherogenesis. Apart from lipid lowering therapy, no intervention has hitherto proved clinically effective in preventing late vein graft failure which clearly constitutes a major clinical and economic problem that needs to be urgently resolved. However, we have studied the effect of external synthetic stents and sheaths in pig models of vein into artery interposition grafting and found them to have a profound effect on vein graft remodelling and thickening. In this review, therefore, we will summarise the mechanisms underlying vein graft failure and how these stents influence these processes and the possible mechanisms involved as well as the application of these devices in preventing vein graft failure clinically.

Short- and long-term effects of cytochalasin D, paclitaxel and rapamycin on wall thickening in experimental porcine vein grafts

OBJECTIVES

Neointima formation and wall thickening caused by smooth muscle cell proliferation compromise long-term patency of human aorto-coronary vein-grafts. We investigated short- and long-term effects of anti-proliferative pharmacological agents on experimental pig vein-grafts with similar dimensions and kinetics to human coronary grafts.

METHODS AND RESULTS

Saphenous veins were treated for 1 h ex vivo with vehicle or concentrations of cytochalasin D, paclitaxel or rapamycin found to be anti-proliferative in preliminary studies. Vehicle and treated veins were implanted contralaterally, end-to-end into the carotid arteries of pigs. Cytochalasin D 2.5 mug/ml non-significantly reduced neointima formation in 4-week vein-grafts (mean+/-standard error, 2.5+/-0.6 vs. 3.3+/-0.6 mm2, n = 10, p = NS), whilst paclitaxel 10 microM produced significant inhibition (1.7+/-0.2 vs. 3.0+/-0.3 mm2, n = 8, p < 0.01) as did rapamycin 0.1 mg/ml (0.6+/-0.3 vs. 1.7+/-0.5 mm(2), n = 8, p < 0.02). Similar effects were found on total wall cross-sectional area but medial area was unaffected. PCNA staining of 1-week vein grafts confirmed in vivo anti-proliferative effects of paclitaxel (21+/-2 vs. 36+/-3%, n = 5, p < 0.01) and rapamycin (32+/-1 vs. 57+/-6%, n = 6, p < 0.005); neither agent stimulated loss of endothelium at these concentrations. Neointima and total wall area increased significantly between 4- and 12-weeks in all vein-grafts such that there was no longer a significant effect on neointima formation of either paclitaxel (7.5+/-1.3 vs. 8.9+/-1.9 mm2 in control, n = 5, p = NS) or rapamycin (6.0+/-0.9 vs. 7.9+/-1.1 mm2 in control, n = 9, p = NS) or on total wall area in 12-week grafts.

CONCLUSIONS

Pre-treatment of saphenous vein with anti-proliferative agents paclitaxel or rapamycin reduced neointima and total wall area after 4 weeks but continued growth abolished differences by 12 weeks. These results may help to understand the failure of clinical studies using anti-proliferative treatments in vein-grafts.

Acquiring proficiency in off-pump surgery: traversing the learning curve, reproducibility, and quality control

As the risk profile of patients considered for surgical revascularization worsens, the cumulative benefit of off-pump coronary artery bypass (OPCAB) over conventional coronary artery bypass grafting, in terms of lower morbidity and reduced healthcare costs, may increase. There is still resistance to the introduction of OPCAB surgery however, its practice is variable and surgical residents are rarely trained in these techniques. This article considers how the learning curve in OPCAB may be negotiated and prospectively monitored to ensure quality control. The evidence suggests that situations in which suitable senior expertise exists, OPCAB surgery can be introduced into surgical practice and safely taught to trainees without detriment to patients. This is achieved by a progressive increase in the complexity of the case mix and careful early supervision. The introduction of OPCAB has coincided with the increasing use of control charts as quality control tools. Performance monitoring provides reassurance that patients are not being put at risk during the introduction of OPCAB; control chart methods can be used prospectively for real time performance monitoring by consultant surgeons and residents alike. These techniques may ultimately be used to determine proficiency and accreditation. Increasing use of parallel training techniques, the development of structured training programs that encompass OPCAB and other new technologies in cardiac surgery, coupled with objective performance monitoring are warranted to meet the needs of a changing patient population.

Reactive oxygen species and erectile dysfunction: possible role of NADPH oxidase

Erectile dysfunction (ED) is a widespread condition, the incidence of which is increasing globally. ED is also indicative of underlying vasculopathy and represents a predictor of more serious cardiovascular disorders. Understanding the aetiology of ED may therefore provide invaluable pointers to the pathobiology of other cardiovascular diseases (CVDs) and syndromes. It follows, too, that therapeutic interventions that are successful in treating ED may, ipso facto, be effective in treating the early stages of conditions that include atherosclerosis, angina, plaque rupture and diabetic angiopathy. One common pathological denominator in both CVD and ED is oxidative stress, that is, the overproduction of reactive oxygen species (ROS), in particular, superoxide (O(2)(*-)) and hydrogen peroxide (H(2)O(2)). In this review, therefore, we consider the aetiology and pathobiology of O(2)(*-) in promoting ED and focus on NADPH oxidase as an inducible source of O(2)(*-) and H(2)O(2). Therapeutic strategies aimed at reducing oxidative stress to improve erectile function are also discussed.

The effect of diabetes mellitus on patients undergoing coronary surgery: a risk-adjusted analysis

BACKGROUND

Surgical case-mix is seriously worsening, and the results of surgical revascularization on high-risk cohorts should be continuously evaluated. This study investigates the influence of diabetes mellitus on the short and midterm outcome in the modern era of coronary surgery.

METHODS AND RESULTS

Patients who underwent first-time coronary artery bypass grafting from April 1996 to October 2003 were classified into diabetic and nondiabetic groups. Data were prospectively collected and retrospectively analyzed. A total of 5259 patients were studied, and of these 877 (17%) were diabetic. Patients with diabetes were more likely to be female, have a higher body mass index, be in an advanced New York Heart Association class and Canadian Cardiovascular Society class, have a history of congestive heart failure, have a poor ejection fraction, renal failure, and more extensive coronary artery disease than the nondiabetic group (P < .001 for all). In-hospital mortality was 2.2% and 1% for diabetic and nondiabetic patients, respectively; however, diabetes was not found to be an independent risk factor for in-hospital mortality (odds ratio = 1.63; 95% confidence interval 0.92-2.88; P = .089). Postoperative complications were comparable in the two groups, with only renal, neurologic, and gastrointestinal complications significantly associated with diabetes (all P < or = .05). There was no association between diabetes mellitus and postoperative infective complications. Diabetes remained an independent predictor of 5-year mortality (hazard ratio 1.55; 95% confidence interval 1.22-1.96; P < .001) and of lower 5-year cardiac-related event-free survival.

CONCLUSION

Despite a worsening cohort, diabetic patients could be surgically revascularized with low morbidity and mortality, comparable with control patients. The negative effect of diabetes mellitus on the longer-term mortality and morbidity remains a problem.

A randomized trial of tranexamic acid in combination with cell salvage plus a meta-analysis of randomized trials evaluating tranexamic acid in off-pump coronary artery bypass grafting

OBJECTIVES

We sought to evaluate the effectiveness of tranexamic acid in off-pump coronary artery bypass grafting surgery, either when used in combination with mechanical cell salvage or when used alone.

METHODS

One hundred patients were randomized to either 2 g of tranexamic acid as an intravenous bolus before sternotomy or to placebo. Intraoperative and postoperative cell salvage was used in all patients. The primary end point was early postoperative blood loss (within 4 hours). To evaluate the efficacy of tranexamic acid in isolation, we also performed a meta-analysis of 4 randomized trials identified from a systematic literature search. The primary end point of the meta-analysis was red cell transfusion.

RESULTS

In our randomized trial patients in the tranexamic acid group had a significant reduction in early postoperative blood loss, (median difference, 50 mL; 95% confidence interval, 15-100 mL; P < .01); however, there was no reduction in the frequency of blood component transfusion. Patients in the placebo group received a significantly larger volume of autotransfused red cells (median difference, 120 mL; 95% confidence interval, 0-220 mL; P = .02). The meta-analysis demonstrated a significant reduction in red cell transfusions in patients receiving tranexamic acid compared with those receiving placebo (risk ratio, 0.48; 95% confidence interval, 0.24-0.97; P = .041). There was also a reduction in the frequency of any allogeneic blood component transfusion, as well as a highly significant reduction in postoperative blood loss, in patients receiving tranexamic acid (P < .001).

CONCLUSIONS

Tranexamic acid reduces blood loss and transfusion requirements in off-pump coronary artery bypass grafting surgery. A reduction in allogeneic blood transfusion was not evident in the presence of perioperative cell salvage. These data support the routine use of tranexamic acid in off-pump coronary artery bypass grafting surgery.

Influence of concomitant coronary artery bypass graft on outcome of surgery of the ascending aorta/arch

BACKGROUND

Surgery of the ascending aorta with or without arch is being performed in an increasingly elderly population with risks of coexisting coronary artery disease.

AIM

To define specific groups requiring coronary artery bypass graft (CABG) and to analyse the influence of concomitant CABG on outcome.

DESIGN

Over a 10-year period in a single institution, 296 consecutive procedures on the ascending aorta with or without arch were carried out in 291 patients. CABG was required in 42 (14.2%) procedures. In 24 (57%) patients, CABG was planned preoperatively and in 18 (43%) patients, on a salvage basis.

RESULTS

In-hospital mortality for patients undergoing concomitant CABG was higher (21.4% v 11%, p<0.06). Adjusting for baseline and operative characteristics, this was attributable to operative priority, and was not a consequence of concomitant CABG (adjusted OR 0.30, 95% CI 1.1 to 8.31; p = 0.48). However, in-hospital mortality was significantly higher when CABG was performed as salvage rather than as a planned procedure (38.9% v 8.9%, p = 0.025), and this difference remained after adjusting for confounding variables (adjusted OR 16.2, 95% CI 1.03 to >200; p = 0.047). The 3-year survival was significantly lower with concomitant CABG (59% v 81.9%, p<0.001).

CONCLUSIONS

In association with surgery of the ascending aorta with or without arch planned concomitant CABG did not entail any added operative risk. However, salvage CABG, which occurred almost exclusively in association with emergency cases, was associated with a higher early mortality. Patients needing concomitant CABG had worse survival at 3 years compared with those requiring isolated surgery of the ascending aorta with or without arch.

Reactive oxygen species, vascular disease and cardiovascular surgery

Oxidant stress [ OS ] is a condition in which cells are exposed to excessive levels of either molecular oxygen or chemical derivatives of oxygen called reactive oxygen species [ROS], principal amongst which is superoxide [O2-]. It is becoming increasingly apparent that O2- is a key risk factor for cardiovascular disease [CVD], including atherogenesis, reperfusion injury, angina, restenosis following balloon angioplasty and vein graft failure. When one considers the multiplicity of effects of O2-, this is perhaps not surprising, as it promotes vascular smooth muscle cell proliferation, damages the endothelium, promotes lipid oxidation and activates blood cells. However, perhaps the key reaction of O2- is that with nitric oxide [NO] to form peroxynitrite [ONOO] resulting in a depletion of endogenous vascular NO. Reduced NO formation is also now firmly associated with the aetiology of CVD and as such NO donors may become a major class of drugs. Furthermore, risk factors for CVD, in particular diabetes mellitus [DM], dyslipidaemia, and hyperhomocysteinaemia are all associated with OS. As such, it is becoming increasingly apparent that novel antioxidant therapies, including the gene transfer of antioxidant enzymes, are potentially valuable in the treatment of CVD. In this review, the aetiology of OS and CVD is discussed with particular emphasis on NO. The interactions of risk factors and how this pathophysiology relates to the design of effective novel strategies to treat CVD is also considered. Particular emphasis is also placed on OS and cardiovascular surgery.

Changes in myocardial free amino acids during pediatric cardiac surgery: a randomised controlled trial of three cardioplegic techniques

OBJECTIVE

The developing heart has a much greater dependence on amino acid (AA) metabolism than the adult heart in determining its ischemic tolerance. Blood cardioplegia preserves myocardial free AAs in adult hearts but no clinical studies have looked at the effect of different cardioplegic techniques on intracellular free AAs in the pediatric heart.

METHODS

Pediatric patients were randomised to receive intermittent antegrade cold crystalloid (CC), cold blood (CB) or cold blood cardioplegia with a 'hot shot' (CB+HS). Right ventricular biopsies were collected prior to ischemia, at the end of ischemia and 20 min after reperfusion. Amino acid levels were analysed as repeated measures, adjusting for baseline levels. Data were analysed separately for acyanotic and cyanotic patients.

RESULTS

Of 103 patients recruited, 32 (22 acyanotic and 10 cyanotic), 36 (24/12) and 35 (25/10), respectively were allocated to CC, CB and CB+HS groups. Cyanotic patients were significantly younger with longer cross-clamp times. In acyanotic patients, there were no significant effects of cardioplegic method on aspartate, glutamine, taurine, alanine or branched chain AA levels (all p>0.05). However, in cyanotic patients, there were significant interactions of cardioplegic method and time (all p<0.05) for all amino acids, with patients allocated to CB+HS having higher levels after reperfusion compared with CC, and patients allocated to CB having intermediate levels.

CONCLUSIONS

For cyanotic patients (younger, longer cross-clamp times), CB+HS preserves myocardial free AAs better than CC; CB gives an intermediate effect. In acyanotic patients, AA levels (all p>0.15) and group means were similar both at the end of ischemia and after reperfusion.

Morbidity and mortality following acute conversion from off-pump to on-pump coronary surgery

OBJECTIVE

Many studies have described reduced morbidity in hospital and equivalent midterm outcomes with off-pump coronary artery bypass (OPCAB) surgery compared to conventional CABG (CABG-CPB). However, OPCAB is sometimes converted acutely to CABG-CPB. We describe the risk of acute conversion and compare patients' outcomes for acutely converted OPCAB with unconverted OPCAB and CABG-CPB.

METHODS

Consecutive acute conversions, i.e. OPCAB patients in whom CPB was instituted urgently for hemodynamic or electrical instability, cardiac arrest or uncontrolled bleeding, were compared with propensity-matched unconverted OPCAB and CABG-CPB patients. Relative risks of death and complications in hospital, and subsequent survival were estimated.

RESULTS

The risk of acute conversion between 1996 and 2004 was 1.1% (27/2492): 5.1% in the first 2 years, 2.2% in the third year and 0.8% subsequently. Odds ratios for death in hospital compared to unconverted OPCAB and CABG-CPB were 4.4 (95% confidence interval (CI) 0.67-29.1) and 4.7 (95% CI 1.03-21.1), respectively, and ranged from 0 to 4.5 for serious complications. Converted patients had an increased hazard of death for 3 years after surgery compared to unconverted OPCAB (hazard ratio 3.21, 95% CI 1.20-8.59) and CABG-CPB patients (hazard ratio 3.23, 95% CI 1.41-7.39).

CONCLUSIONS

Experienced OPCAB surgeons have a low risk of acute conversion. Acutely converted patients have a moderately increased risk of death and serious complications in hospital. These risks are difficult to quantify precisely because conversion is rare.

Coronary surgery in patients with preexisting chronic atrial fibrillation: early and midterm clinical outcome

BACKGROUND

The purpose of this study was to investigate the effect of preexisting atrial fibrillation on early and midterm clinical outcome in patients undergoing coronary surgery.

METHODS

All elective patients undergoing coronary artery bypass grafting surgery between April 1996 and September 2002 were investigated. Patients were grouped according to their preoperative cardiac rhythm: sinus rhythm (SR) or preexisting atrial fibrillation (AF). In-hospital clinical outcomes and 5-year patient survival and cardiac-related event-free survival were compared using regression methods to adjust for differences between the groups. In all, 5,092 patients were identified, 175 (3.4%) with a history of preexisting AF. These patients were older (median, 64 versus 68 years) and had higher Parsonnet scores (median, 4 versus 8) than the SR group. Previous myocardial infarction, cerebrovascular accident, hypertension, diabetes mellitus, renal impairment, peripheral vascular disease, ejection fraction less than 50%, previous surgery, congestive heart failure, and use of angiotensin-converting enzyme inhibitors were also more common in the AF group.

RESULTS

There were 60 in-hospital deaths (1.2%), with no difference between the two groups (odds ratio 1.02, 95% CI: 0.35 to 2.94). Atrial fibrillation patients were more likely to need intraoperative inotropes (p = 0.044), postoperative intra-aortic balloon pump (p = 0.038), and were less likely to be discharged within 6 days (p = 0.017). The risk of death in the 5 years after surgery was higher in the AF group (relative risk 1.49, 95% CI: 1.06 to 2.08, p = 0.020). In the AF group, 109 (62.2%) patients were cardioverted spontaneously by surgery, but only 69 (39.4%) remained in SR until discharge. Longer-term rhythm follow-up data were available for 48 of these 69 patients, and only 36 remained in SR at a median follow-up of 1,483 days (interquartile range, 1,120 to 2,209). Spontaneous conversion to SR after surgery did not confer a midterm survival benefit (p = 0.91).

CONCLUSIONS

Preexisting AF in patients undergoing coronary artery bypass graft surgery is not associated with increased in-hospital mortality and major morbidity; however, it is a risk factor for reduced 5-year survival. Spontaneous cardioversion to SR during surgery is transient in the majority of patients and is not associated with midterm survival benefit.

Superoxide auto-augments superoxide formation and upregulates gp91phox expression in porcine pulmonary artery endothelial cells: Inhibition by iloprost

Central to the aetiology of Acute Respiratory Distress Syndrome (ARDS) is superoxide, the principal source of which is nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase). To test whether superoxide may influence NADPH oxidase expression directly, the effect of incubation of superoxide with porcine pulmonary arterial endothelial cells on the expression of gp91(phox) (a catalytic subunit of NADPH oxidase) and superoxide formation was investigated. Since iloprost has been purported to be potentially effective in treating ARDS, the effect of iloprost on superoxide-mediated effects was also studied. Pulmonary artery endothelial cells were incubated with xanthine/xanthine oxidase which generates superoxide, or tumour necrosis factor alpha (TNFalpha) or thromboxane A(2) analogue, U46619 (+/- superoxide dismutase [SOD] or catalase or iloprost) for 16 h. Cells were then washed and superoxide formation assessed spectrophometrically and gp91(phox) expression using Western blotting. The role of NADPH oxidase was also studied in the above settings using apocynin, an NADPH oxidase inhibitor. Superoxide, TNFalpha and U46619 elicited an increase in the formation of superoxide and induced gp91(phox) expression in pulmonary artery endothelial cells following a 16 h incubation an effect blocked by the continual presence of SOD and apocynin but not catalase. Apocynin completely inhibited superoxide formation induced with xanthine/xanthine oxidase after the 16 h incubation. Rotenone and allopurinol were without effect. Iloprost inhibited the formation of superoxide and gp91(phox) expression. These data demonstrate that superoxide upregulates gp91(phox) expression in pulmonary artery endothelial cells and thus augments superoxide formation, an effect blocked by iloprost. This constitutes a novel mechanism by which vascular superoxide creates a self-perpetuating cascade that may be of importance to the etiology of ARDS and other vasculopathies.

Free Amino Acids in Hearts of Pediatric Patients With Congenital Heart Disease: The Effects of Cyanosis, Age, and Pathology

BACKGROUND

The immature heart has a much greater dependence than the adult heart on amino acid transamination in determining its ischemic tolerance. Compared with adult hearts, experimental models of the immature heart have quantified higher resting concentrations of free amino acids (AA) which are depleted by acute hypoxia. However, we have found no clinical studies that have looked at the free AA profile of the immature human heart or the effects of cyanosis, age, and pathology upon this.

METHODS

One hundred eighty-one pediatric patients (37 cyanotic, 144 acyanotic) undergoing open-heart surgery were recruited. Myocardial biopsies were collected prior to ischemia and analyzed for free AAs (eg, glutamate, aspartate) using high-performance liquid chromatography. The effects of cyanosis, age, and pathology on amino acid concentrations were estimated by multiple regression modeling with and without controlling for diagnosis; the effects of age and pathology were estimated only in acyanotic children.

RESULTS

Alanine concentrations were about 20% higher in cyanotic than acyanotic patients (p = 0.04). Cyanosis was not associated with any other amino acid levels. In acyanotic patients, after controlling for diagnosis, concentrations of glutamate, aspartate, and alanine decreased from birth to about 8 to 10 years, then started to increase again (p < 0.05 for both linear and quadratic terms); concentrations of taurine and the branched chain AAs decreased steadily with increasing age (p < 0.05). There were significant effects of pathology on glutamate (p = 0.006), glutamine (p = 0.003), and branched chain AA (p = 0.004) levels.

CONCLUSIONS

There is no evidence that chronic hypoxia depletes endogenous AAs. Young age is associated with higher resting AA levels.

Penicillamine administration reverses the inhibitory effect of hyperhomocysteinaemia on endothelium-dependent relaxation and superoxide formation in the aorta of the rabbit

Although hyperhomocysteinaemia is a risk factor for cardiovascular disease, the mechanisms underlying this association have not been elucidated. It has been demonstrated, however, that copper augments the inhibitory effect of homocysteine on nitric oxide (NO)-mediated relaxation of the rat aorta through increased superoxide formation, which reacts with NO thereby reducing the bioavailability of NO. Since it follows that the administration of a copper chelator may blunt the pathogenic impact of hyperhomocysteinaemia, in vivo, the effect of penicillamine administration on NO-dependent relaxation and superoxide formation in the aortae of hyperhomocysteinaemic rabbits was studied. New Zealand White rabbits were fed a methionine-rich (20 g/kg chow) diet for 1 month+/-penicillamine administered orally (10 mg/kg/day) and aortic relaxation elicited with acetylcholine and superoxide measured. The role of NADPH oxidase was also studied using a range of inhibitors and western analysis of gp47(phox) (a catalytic subunit of NADPH oxidase). The methionine-rich diet markedly increased plasma total homocysteine levels. In hyperhomocysteinaemic rabbits there was a marked reduction of acetylcholine-stimulated relaxation and an increase in superoxide formation that were both inhibited with superoxide dismutase and apocynin, an NADPH oxidase inhibitor. Gp47(phox) expression was also increased in aortae from methionine fed rabbits. Penicillamine administration significantly reduced plasma total copper in methionine-fed rabbits compared to controls. Impaired acetylcholine-stimulated relaxation, increased superoxide formation and increased gp47(phox) expression in aortae from methionine-fed rabbits was reversed by penicillamine administration. These data indicate that hyperhomocysteinaemia augments the formation of arterial superoxide through an increase in NADPH oxidase expression/activity which in turn reduces NO bioavailability. Since these effects were reversed by penicillamine, these data consolidate the hypothesis that copper plays a role in mediating homocysteine-induced vasculopathy.

Does oxidative stress change ceruloplasmin from a protective to a vasculopathic factor?

Although ceruloplasmin (CP), a copper containing metalloenzyme, possesses antioxidant properties (e.g. ferroxidase activity), elevated circulating CP is associated with cardiovascular disease (CVD). This ambivalence is possibly due to the capacity of CP, via its coppers, to promote vasculopathic effects that include lipid oxidation, negation of nitric oxide bioactivity and endothelial cell apoptosis. In turn, these effects that are mediated by increased formation of reactive oxygen species (ROS), such as superoxide and hydrogen peroxide. There is also evidence that risk factors for CVD (in particular, diabetes mellitus and hyperhomocysteinaemia) may augment the vasculopathic impact of CP. In turn, it appears that ROS disrupt copper binding to CP, thereby impairing its normal protective function while liberating copper which in turn may promote oxidative pathology. The objective of this review, therefore, is to consider the epidemiology and pathophysiology of CP in relation to CVD, with particular emphasis on the relationship between CP and oxidative stress.

Splanchnic Organ Injury During Coronary Surgery With or Without Cardiopulmonary Bypass: A Randomized, Controlled Trial

BACKGROUND

We investigated the efficacy of coronary surgery with or without cardiopulmonary bypass in protecting the function of the small intestine, liver, and pancreas.

METHODS

Patients were randomized to off-pump coronary artery bypass grafting (OPCAB) or coronary artery bypass grafting with cardiopulmonary bypass (CABG-CPB). Small intestine function was assessed by differential four sugars (O = methyl-D-glucose, D-xylose, L-rhamnose, and lactulose) permeability and absorption tests. Liver function was assessed by monoethylglycinexylidide/lidocaine ratios and by serial measurements of transaminases (aspartate transaminase and alanine-amino transferase), bilirubin, and alkaline phosphatase. Pancreatic function was assessed by serial measurements of insulin/glucagon ratio, amylase, and glucose. Forty patients were recruited (20 per group).

RESULTS

Permeability and absorption were more impaired in the OPCAB group immediately after surgery, but returned to baseline levels in both groups by postoperative day 5 (interaction of surgery type and time; p = 0.05 and p = 0.02, respectively). Monoethylglycinexylidide/lidocaine ratios were not different in the two groups. Aspartate transaminase and alanine-amino transferase levels were higher in the CABG-CPB group for the first postoperative day, but levels converged by day 3 (interaction of surgery type and time; p < 0.0001 and p = 0.04, respectively). The bilirubin level for the OPCAB group overshot the CABG-CPB group at 36 hours before returning to a similar level 60 hours postoperatively. Amylase levels were higher in the CABG-CPB group than in the OPCAB group (1.17 times; p = 0.03); other markers of pancreatic function showed no differences between the groups.

CONCLUSIONS

Early small intestine function is worse with OPCAB; all functions recover to similar levels in both groups by day 5. Conversely, pancreatic function is worse with the CABG-CPB group than with the OPCAB group. Hepatic metabolic function does not differ by type of surgery to the end of the operation. Postoperative hepatocellular injury was worse with the CABG-CPB group.

Conventional surgery with aortic cross-clamping

This article provides a brief description of how to perform proximal and distal anastomosis on the arrested empty heart along with the grafting strategy and utilisation of different conduits in coronary artery revascularisation. Sequential grafting and indications of coronary artery revascularisation has also been described.

Novel Repair for Late Posttraumatic Aortic Valve Injury and Root Pseudoaneurysm

We report a case of posttraumatic aortic valve regurgitation and pseudoaneurysm of the aortic root diagnosed 22 months after a road traffic accident. The surgical treatment consisted of exclusion of the pseudoaneurysm with direct closure of the entry tear in the right coronary sinus followed by insertion of a Toronto stentless prosthesis (St. Jude Medical, St. Paul, MN). This surgical approach aimed to cover the repaired entry tear ensuring exclusion of the site. Recovery was uneventful and 12 month follow-up was unremarkable.

Incomplete revascularization during OPCAB surgery is associated with reduced mid-term event-free survival

BACKGROUND

The aim of this study was to compare early and mid-term outcome in patients undergoing off-pump coronary artery bypass surgery who have had complete revascularizations and incomplete revascularizations (IRs).

METHODS

Patient and operative data were collected prospectively for all patients who had off-pump coronary artery bypass surgery. Patients with multivessel disease were classified as having IR if the number of diseased coronary systems (left anterior descending coronary artery, circumflex and right coronary artery) exceeded the number of distal anastomoses. In-hospital outcomes, survival, and event-free survival were compared between patients with complete revascularization and IR using propensity scores to take account of differences in prognostic factors.

RESULTS

There were 1,479 off-pump coronary artery bypass surgery patients between April 1996 and December 2002 (30% of all coronary artery bypass graft patients), and 16.0% (237 patients) had IRs. Patients with IRs tended to be older and were female, had more extensive disease, worse dyspnea, a higher Parsonnet score, poorer ejection fraction, congestive cardiac failure, asthma or chronic obstructive airways disease, and previous cardiac surgery. The adjusted hazard ratio for patient survival with IRs versus complete revascularizations was 1.56 (95% confidence interval, 1.19 to 2.06; p = 0.001). Analyses for multiple time periods confirmed that IRs had a significantly increased risk of death, but also that the risk disappeared after the first 4 to 6 months of follow-up (p < 0.0001).

CONCLUSIONS

Compared with off-pump coronary artery bypass surgery patients with complete revascularizations, those with IRs have reduced survival, but only in the first 4 to 6 months after surgery. Patients' preoperative condition, rather than IR itself, may explain these findings because IRs should have mid-term as well as early effects.

Retinal and Cerebral Microembolization During Coronary Artery Bypass Surgery

Background— We sought to compare the effects on ophthalmic function of coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) and off-pump (OPCAB) grafting and to investigate whether retinal microvascular damage is associated with markers of cerebral injury.

Methods and Results— Retinal microvascular damage was assessed by fluorescein angiography and color fundus photography. Ophthalmic function was tested by the logarithm of the minimum angle of resolution visual acuity (VA), and cerebral injury, by transcranial Doppler ultrasound–detected emboli and S100 protein values. Twenty patients were randomized. Fluorescein angiography and postoperative VA could not be obtained for 1 CABG-CPB patient. Retinal microvascular damage was detected in 5 of 9 CABG-CPB but in none of 10 OPCAB patients (risk difference, 55%; 95% confidence interval [CI], 23% to 88%; P =0.01). Color fundus photography detected microvascular damage in 1 CABG-CPB patient but in no OPCAB patients; this lesion was associated with a field defect, which remained after 3 months of follow-up. There was no difference in postoperative VA. Doppler high-intensity transient signals (HITS) were 20.3 times more frequent in the CABG-CPB than in the OPCAB group (95% CI, 9.1 to 45; P <0.0001). Protein S100 levels were higher in the CABG-CPB than in the OPCAB group 1 hour after surgery ( P <0.001). HITS were 14.7 times more frequent (95% CI, 3.5 to 62; P =0.001) and S100 level 2.1 times higher (95% CI, 1.3 to 3.5; P =0.005) when retinal microvascular damage was present.

Conclusions— The relative frequency of retinal microvascular damage between groups shows the extent to which the risk of cerebral injury is reduced with OPCAB. Imaging of part of the cerebral circulation provides evidence to validate markers of cerebral injury.