Renal function assessed by two different formulas and incidence of myocardial infarction and death in middle-aged men and women.

BACKGROUND: Chronic kidney disease predicts mortality in the general population, but less is known about the association with incidence of first myocardial infarction. We evaluated glomerular filtration rates (GFR) estimated by the Modification of Diet in Renal Disease study (GFR-MDRD) equation and the Mayo formula (GFR-Mayo) as predictors of myocardial infarction and death. METHODS: In 571 353 Swedish men and women, undergoing health controls, with mean age 45 years, and no previous myocardial infarction, hazard ratios were calculated to assess the association between renal function and incidence of myocardial infarction and all-cause mortality, respectively. Glomerular filtration rate 60-90, 30-60 and <30 mL per minute per 1.73 m(2), was defined as mildly, moderately and severely decreased GFR, respectively. RESULTS: There were 19 510 myocardial infarctions and 56 367 deaths during 11.6 years of follow-up. Hazard ratios (and 95% confidence intervals) for myocardial infarction, using GFR-Mayo were 1.11 (1.06-1.16) for mildly, 1.32 (1.18-1.48) for moderately and 2.54 (1.90-3.40) for severely decreased GFR. The corresponding figures for GFR-MDRD were 1.01 (0.96-1.05), 1.23 (1.14-1.32) and 2.49 (1.85-3.35). Mortality was increased at all levels of reduced GFR-Mayo and at moderately or severely decreased GFR-MDRD. CONCLUSIONS: Already mildly decreased GFR increase the risk of myocardial infarction and death in the general population. The association with adverse outcomes is stronger when GFR-Mayo rather than GFR-MDRD is used to assess renal function.

Work disability patterns before and after incident acute myocardial infarction and subsequent risk of common mental disorders: A Swedish cohort study.

This study investigated the extent to which work disability patterns including sickness absence and disability pension (SA/DP) before and after acute myocardial infarction (AMI) were associated with subsequent common mental disorders (CMDs) such as depression and anxiety in AMI patients without previous CMD. Total 11,493 patients 26-64 years with incident AMI during 2008-10 were followed up for CMD (measured as antidepressant prescription) through 2013. Four SA/DP trajectory groups during the 3-years pre-AMI and 1-year post-AMI were identified. Hazard ratios (HRs) with 95% confidence intervals for subsequent CMD were estimated in Cox models. Higher pre-AMI SA/DP annual levels (>1-12 months/year) were associated with 40-60% increased CMD rate than the majority (78%) with low increasing levels (increasing up to 1 month/year). Regarding post-AMI findings, constant high (~25-30 days/month) SA/DP levels within the first 3 months was associated with a 76% higher CMD rate, compared to constant low (0 days/month). A gradually decreasing post-AMI SA/DP pattern over a 12-month period suggested protective influences for CMD (HR = 0.80). This is the first study to demonstrate that pre- and post-AMI work disability patterns are associated with subsequent CMD risk in AMI patients. Work disability patterns should be considered as an indicator of AMI prognosis in terms of CMD risk.

Comparison of early and late mortality in men and women after isolated coronary artery bypass graft surgery in Stockholm, Sweden, 1980 to 1989.

OBJECTIVES: We sought to analyze early and late mortality after coronary artery bypass graft surgery (CABG) in relation to gender. BACKGROUND: Early mortality after CABG is generally higher in women than in men, but the causes are controversial. Few studies have investigated long-term mortality after CABG in relation to gender. METHODS: In all, 3,326 men and 607 women underwent isolated CABG in Stockholm from 1980 to 1989. Mortality for these patients was followed by means of the National Cause of Death Register, from the time of operation until the end of 1990. Survival was evaluated by life-table methods and by proportional hazards regression. RESULTS: Early mortality (within 30 days) was 3% in women and 1.7% in men, corresponding to a relative risk of 1.8 (95% confidence interval [CI] 1.0 to 3.0) in women compared with men. When age and body surface area were taken into account, the relative risk was 1.0 (95% CI 0.5 to 2.0), which was not markedly different but multivariate analyses that included hypertension, diabetes mellitus, previous myocardial infarction, left ventricular function and number of diseased vessels. Only small gender differences in mortality were observed for 5 years after the operation among those who survived for 30 days. CONCLUSIONS: The results suggest that men and women run similar risks of early and late mortality after CABG when patient characteristics are taken into account.

Hemodynamic performance of cryopreserved aortic homograft valves during midterm follow-up.

OBJECTIVES: The aim of this prospective study of adult patients operated with a cryopreserved aortic homograft was to use serial echocardiographic data to evaluate the postoperative hemodynamic performance of these valves. BACKGROUND: Only limited data on hemodynamic performance of aortic homografts at rest and during exercise are available. Controversy also exists regarding incidence and progression of aortic regurgitation (AR). METHODS: Fifty-nine patients aged 39-86 years who received an aortic homograft (median size 21 mm) implanted with subcoronary technique were studied with serial Doppler-echocardiography (D-E). In 31 of these patients, D-E also was performed during supine exercise. RESULTS: Overall survival was 100% during a median follow-up of 28 months (range 4-54). During follow-up AR grade II or more was detected in 25% of the patients with an increasing time-related risk of developing AR. Maximum and mean pressure differences at 7 months follow-up calculated with the short form of the Bernoulli equation were 11.4 (4.6) and 5.5 (2.1) mm Hg, respectively. During supine exercise that increased cardiac output 72%, maximum pressure difference increased from 11.9 (5.2) to 18.5 (9.5) mm Hg. CONCLUSIONS: The aortic homograft valve shows low pressure differences at rest and during exercise, but AR grade I or II is often seen during follow-up. As AR progresses with time we stress the importance of echocardiographic follow-up of patients with aortic homografts.

Myocardial and non-myocardial release of myoglobin and creatine-kinase MB following cardiac operations with hypothermic potassium cardioplegia.

Serum time-activity curves for myoglobin, creatine-kinase (CK) and its isoenzyme MB were determined during and after coronary bypass surgery and aortic valve replacement. Hypothermic potassium cardioplegia was the method employed to initiate cardiac arrest. Cardiac myoglobin and CK-MB release rates were maximal 0.5 to 1.0 h post aortic cross-clamp release (PACR) with maximal concentrations at 1 and 4 h PACR respectively. The cardiac release ceased within 5 h PACR but was followed by a noncardiac release with maximal concentrations from 10 to 35 h PACR. The cardiac myoglobin release was significantly lower in the coronary bypass group, whereas no significant intergroup difference was observed for CK-MB. The cumulative CK-MB release corresponded roughly to about 5 g of myocardium.

Biphasic pro-thrombotic and inflammatory responses after coronary artery bypass surgery.

Early graft failure after coronary artery bypass grafting (CABG) is related to thrombosis and inflammation in the grafted vessel(s). The time courses of, and relationships between, pro-thrombotic and inflammatory responses to CABG surgery have, however, not been well defined. Fifteen patients undergoing CABG were examined before, and 1 h, 1 day, 7 days, and 3 months after surgery. Cellular markers of platelet and leukocyte activation were monitored by whole blood flow cytometry, and plasma markers of pro-thrombotic and inflammatory responses were analyzed by immunoassays. CABG immediately increased circulating P-selectin-positive platelets, leukocyte CD11b expression, and platelet-leukocyte aggregates (PLAs). Thrombin generation (F1 + 2 levels) and cytokine release [tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-8, and IL-10], soluble P-selectin, and soluble E-selectin also increased immediately. These alterations persisted during the first week after surgery, with re-bound increases of circulating activated platelets and PLAs, TNF-alpha, and F1 + 2 on day 7. Platelet and PLA responsiveness to in vitro stimulation was suppressed immediately after CABG, but markedly enhanced 1 week after surgery. After 3 months, plasma soluble P-selectin, F1 + 2, and IL-10, and monocyte CD11b expression were still slightly elevated compared with baseline. In conclusion, CABG induces marked pro-thrombotic and inflammatory responses, which persist for at least 1 week. Platelet activation, platelet reactivity, PLA formation, thrombin generation, and TNF-alpha release show a second peak 1 week after surgery. These findings suggest that intensified and prolonged antithrombotic/inflammatory treatment should be considered after CABG surgery.

Angiographic studies of internal mammary artery grafts 11 years after coronary artery bypass grafting.

Of 99 consecutive patients with 101 internal mammary artery grafts, 91 of 97 hospital survivors (94%) underwent angiography 2 weeks after operation, 84 of 96 survivors (88%) after 1 year, 66 of 88 survivors (75%) after 5 years, and 37 of 69 survivors (54%) after 11 years (range 10 to 13 years). Thirty-five of the 37 patients who consented to a fourth postoperative angiographic study (95%, confidence limits 86% to 100%) still reported relieved angina 11 years after the operation, and seven patients (19%, confidence limits 5% to 33%) were completely free of symptoms. Angiographic findings in 30 patients with symptoms of angina were progression of the coronary artery disease in 22, (73%, confidence limits 56% to 91%), occluded or stenosed grafts in nine (30%, confidence limits 12% to 48%), and nonbypassed obstructions in six patients (20%, confidence limits 4% to 36%). The cumulative 11-year patency rate was 88%, confidence limits 81% to 95%, for internal mammary artery grafts and 61%, confidence limits 45% to 76% for saphenous vein grafts. Six of 18 saphenous vein grafts (33%, confidence limits 19% to 58%) occluded in the interval between 5 and 11 years after operation, and gross wall irregularities were observed in six of the 12 patent saphenous vein grafts. Unligated side branches and stenosis of the internal mammary artery did not prevent long-term graft patency. Internal mammary artery graft failures were related to technical errors during the operation and occurred when the internal mammary artery was used to bypass a low-grade coronary artery stenosis. In one patient, regression of a coronary artery stenosis was associated with a marked decrease in luminal size of the internal mammary artery graft before the 5-year follow-up. This single internal mammary artery graft became occluded in the interval between 5 and 11 years after the operation. Eleven of 36 internal mammary artery grafts (31%, confidence limits 14% to 47%) increased 15% to 40% in luminal diameter as a result of increased myocardial blood demand before the 11-year follow-up.

Work capacity and central hemodynamics thirteen to twenty-six years after repair of tetralogy of Fallot.

Exercise tests and cardiac catheterization were performed in 53 patients, 13 to 26 years after intracardiac repair of tetralogy of Fallot. At the time of repair, the median age was 7 years, and 60% of patients with cyanosis had had a previous palliative procedure. The right ventriculotomy was closed without a patch in 21 patients (40%), a patch restricted to the right ventricle was inserted in 18 patients (34%), and in 14 (26%) the patch extended across the pulmonary anulus. At follow-up, 94% of the patients were free of symptoms. Symptom-limited work capacity was 87% of the predicted value (95% confidence limits, 82% to 94%). Work capacity was inversely related to age at follow-up, to right ventricular systolic pressure at rest, and to presence of moderate or severe pulmonary valve regurgitation. Cardiac output in relation to oxygen uptake was reduced in 74% of patients during exercise. In 12 patients (23%), systolic pressure at rest in the right ventricle was 50 mm Hg or higher. Systolic pressure during exercise in the right ventricle was lower in patients without a patch than in those with a patch and was abnormally high in all groups compared with healthy subjects. The ratio of right to left ventricular pressure was significantly lower than measurements taken immediately after repair. An intracardiac left-to-right shunt was present in 6 patients (11%). Three patients required invasive treatment as a result of our follow-up. We conclude that work capacity was moderately reduced 13 to 26 years after repair of tetralogy of Fallot and was adversely influenced by right ventricular hypertension and pulmonary valve regurgitation. Intermittent lifelong surveillance is advocated, because patients without symptoms may have hemodynamic abnormalities that necessitate intervention.

Pulmonary function thirteen to twenty-six years after repair of tetralogy of Fallot.

Lung function was evaluated in 68 patients 13 to 26 (median 19) years after repair of tetralogy of Fallot. Age at repair was 7 years (9 months to 42 years) and 51% had a palliative shunt. An outflow patch was inserted in 56%. Median vital capacity was 84% of predicted, forced expiratory volume in 1 second 83%, maximal voluntary ventilation at 40 breaths/min 70%, and diffusing capacity for carbon monoxide 77% of predicted. Scintigraphy demonstrated abnormal pulmonary perfusion in 86%. Average right lung perfusion was 57% (predicted 52%). Regional hypoperfusion could in some patients be explained by previous palliative shunt, pulmonary artery obstruction, or presence of aortopulmonary collaterals. Median symptom-limited work capacity was 82% (95% confidence limits 78% to 90%) of predicted. Twenty-eight physically active patients had high values for symptom-limited work capacity, vital capacity, forced expiratory volume in 1 second, and maximal voluntary ventilation at 40 breaths/min compared with those of inactive patients. Lung function variables were related to physical exercise and previous palliative shunt. Moderate or severe pulmonary valve incompetence had negative but not significant influence on lung function. There was no significant influence of acyanosis before repair, use of transannular patch, duration of follow-up, or smoking. We found moderately reduced work capacity and lung function late after repair of tetralogy of Fallot that did not cause symptoms. Lung function variables were high in young active male patients and low in patients with previous palliative shunt. A better lung function in active patients indicates that physical activity should be encouraged after repair of tetralogy of Fallot.

Cardiac myxoma: 40 years' experience in 63 patients.

BACKGROUND: Cardiac myxomas were resected in 63 patients, including the first successful procedure in the world. METHODS: Patient data and data obtained during follow-up of the survivors were reviewed. RESULTS: Preoperatively, valve obstruction occurred in 56% and emboli in 32% of the patients. The myxomas were located in the left atrium in 88%, right atrium in 10%, and both atria in 1 patient (1.6%). One patient died early, and 5 died late. The 20-year survival rate was 85%. At a median of 13 years (range, 1 month to 42 years) after resection, 26% of the survivors reported having various cardiopulmonary symptoms, 5% had had thromboembolic events, and 69% were asymptomatic. After 2 years, there was a recurrence in a young woman who had had a multifocal myxoma at the time of the primary operation. No other evidence of recurrence was found at autopsy or during repeat echocardiography in the remaining patients during an observation period of 787 patient-years. CONCLUSIONS: Surgical resection of a single myxoma is a safe and effective treatment, with a low risk of recurrence. After uncomplicated resection, the frequency with which postoperative echocardiography is performed should be limited.

Magnetic resonance imaging of the brain before and after open heart operations.

Magnetic resonance imaging of the brain was performed in 29 adult male patients before and 1 week after elective coronary artery bypass grafting to study the cerebral effect of cardiopulmonary bypass. The mean age of the patients was 60 years (range, 45 to 69 years). During cardiopulmonary bypass, either a bubble oxygenator without an arterial line filter (n = 9), a bubble oxygenator with a depth adsorption filter (n = 10), or a flat-sheet membrane oxygenator without a filter (n = 10) was used. The mean bypass time was 88 minutes (standard deviation, 31 minutes) and did not differ significantly between the three groups. Preoperative magnetic resonance imaging revealed high signal intensity foci on T2-weighted images (white matter abnormalities) in 17 (59%; 95% confidence limits, 39% to 76%) of the 29 patients, all of which were nonspecific and of the common type considered to be related to aging, and all were unchanged at the postoperative examination. Preoperative and postoperative frontal horn indices, bicaudate diameters, and third ventricle widths did not differ significantly regardless of oxygenator type or whether or not an arterial line filter was used during cardiopulmonary bypass. Two patients (7%; 95% confidence limits, 1% to 23%), both receiving bubble oxygenation (1 without a filter and 1 with an arterial line filter) sustained a cerebral infarction during cardiopulmonary bypass.

Haemostatic function in patients undergoing coronary artery bypass grafting: peroperative perturbations and relations to saphenous vein graft closure.

Vein graft failure remains a major problem after coronary artery bypass grafting. Occlusion in the first weeks usually is caused by thrombosis, whereas intimal hyperplasia and eventually atherosclerotic changes with superimposed thrombus formation underlie subsequent closure. The present investigation was conducted as a pilot study to examine whether perturbations of haemostatic function predispose to early saphenous vein graft occlusion after coronary artery bypass grafting. Pre- and postoperative determinations (performed on the first, third, and sixth postoperative days) of haemostatic factors and inhibitors were related to the presence of graft occlusion assessed by angiography at 3 months after surgery in 100 men undergoing elective coronary artery bypass grafting for stable angina pectoris. Occlusion of one or more vein grafts within three months of surgery occurred in 23 of the 100 patients examined. The percentage increase in plasma plasminogen activator inhibitor-1 activity on the first postoperative day was significantly higher in patients who subsequently were found to have vein graft occlusion (p<0.05). Otherwise no postoperative haemostatic measurements were found to predict early vein graft closure. A perturbed plasma plasminogen activator inhibitor-1 response to coronary artery bypass grafting tentatively could be added to the vessel-specific factors that remain the main determinants of early vein graft closure.

The effect of acetylsalicylic acid on fibrin gel lysis by tissue plasminogen activator.

The in vitro effect of acetylsalicylic acid (ASA) on fibrin gel lysis by exogenous t-PA was studied in 13 patients with angina pectoris. Six patients received 75 mg, and seven patients 160 mg of ASA. Plasma clots were formed and lysed in microtiter plate wells and turbidity monitored spectrophotometrically. Mean lysis times in the 75 mg group were 8.7, 11.4 and 11.2 min during ASA treatment, and after 1 and 2 weeks ASA withdrawal respectively. Reduced changes were observed in the 160 mg group. Additionally, a relationship was found between the fibrin fiber mass/length ratio, i.e. fiber thickness in mature clots and lysis times after ASA administration (P = 0.0015). Importantly, fibers are thicker during treatment with ASA. It was subsequently demonstrated that the potential to produce thicker fibers by varying the thrombin concentration has a noticeable effect on turbidimetric profiles in the presence of exogenous t-PA. This effect was similar to the changes observed during and after ASA treatment. Thus, these results suggest that the enhancement of fibrin gel lysis during ASA treatment may be due to alterations in gel structure. In addition, a reduction in the fibrin mass in lower turbidity clots, suggests an added mechanism by which ASA may enhance lysis.

Abnormally high platelet activity after discontinuation of acetylsalicylic acid treatment.

Production of 12-L-hydroxy-5, 8, 10-heptadecatrienoic acid (12-HHT) from platelets and bleeding times were studied in 32 males during acetylsalicylic acid (ASA) treatment and 1 and 2 weeks after withdrawal. All patients (age 42-77 years) had ASA treatment because of angina pectoris. The metabolite 12-HHT is formed in the same amount as the proaggregatory and vasoactive metabolite thromboxane A2. Initially the daily ASA dose was 75 mg (n = 15), 160 mg (n = 12) or 250-300 mg (n = 5). In all patients, median 12-HHT level increased from 40 to 240g/750 x 10(6) platelets (P < 0.001) 1 week after withdrawal of ASA, and four patients had abnormally high values. Median bleeding time decreased from 312 to 268 s (P = 0.003) in the 75 mg group and from 315 to 235 s in the 160 mg group (P = 0.01). Two weeks after withdrawal of ASA, median 12-HHT was 390g/750 x 10(6) platelets and eight patients (25%) had abnormally high values. One patient still had a prolonged bleeding time. Wide interindividual variations were observed in all groups. Our results indicate that rapid withdrawal of ASA, may cause abnormally high 12-HHT levels reflecting increase of thromboxane A2 with possible hazardous effects in patients with cardiovascular disease.

Coronary artery bypass grafting in patients 70 years of age and older. Early and late results.

Ninety-four patients 70 years of age and older underwent coronary artery bypass grafting (CABG) between 1979 and 1985. Thirty-two percent were females. An internal mammary artery was used in 49% and concomitant cardiac procedures were performed in 51% of the operations. Early mortality was 12%. Five of 11 early deaths were from non-cardiac causes: ascending aortic disease (2), cerebral damage (2) and septicaemia (1). Postoperative morbidity included neurological complications in 16%, reoperation for bleeding in 12%, mediastinitis or sternal dehiscence in 4% and perioperative acute myocardial infarction in 4%. At follow-up, a median of 2.5 years after surgery, 83% were completely free from angina, 5% much improved, 9% improved and 3% had unchanged symptoms of angina. Actuarial survival, inclusive of early mortality, was 84% at 3 years. Female sex and concomitant cardiac surgery were common in elderly patients who had CABG. Early mortality from noncardiac causes and postoperative morbidity were increased but dramatic relief of symptoms was achieved in the majority of survivors.

Reduced risk of coronary artery bypass surgery for unstable angina during a 6-year period.

OBJECTIVE: To assess the risk of early death or acute myocardial infarction in patients undergoing isolated coronary artery bypass surgery for unstable coronary artery disease. METHODS: Retrospective observational study of 853 patients operated on because of unstable coronary artery disease during 1990-1995. RESULTS: There were 5.9% deaths and 13.0% nonfatal infarctions < or =30 days. These figures declined during the observation period and were 2.6% and 6.2%, respectively, in 1995. The relative risk of early death or myocardial infarction was 50% less during 1994-1995 than during 1990-1991, after multivariate adjustment for several patient risk factors. The risk of death or infarction was almost twice as high in patients > or =50 years than in those < 50 years of age. Multivariate analysis showed that aortic-cross-clamp time > or =60 min, previous bypass surgery, pre-operative heart failure, emergency surgery, worse Braunwald class and non-use of an internal mammary artery graft were associated with an increased risk of death or infarction. Early mortality was 3.4% (24/702) in unstable patients without symptoms of congestive heart failure, who were not operated on emergently after failed percutaneous coronary intervention and had not had previous cardiac surgery. CONCLUSIONS: We observed a marked reduction of the risk of early death or myocardial infarction after surgery for unstable angina during the 6-year period 1990-1995. The risk reduction was not explained from operations performed on patients with less risk and indicates improved peri-operative patient management.

Reoperations for bleeding after coronary artery bypass procedures during 25 years.

OBJECTIVES AND METHODS: To study the incidence, causes and risk factors of reoperation for bleeding, 8563 coronary artery bypass procedures performed during 1970-1994 were reviewed. RESULTS: Patients operated on during 1990-1994 were older, the internal mammary artery was used more frequently, more grafts were inserted, more combined and redo bypass procedures were performed than during 1970-1989. There were 402 early resternotomies but in 24 patients (6%) no bleeding was encountered and the compromised haemodynamics was caused by left ventricular failure. Postoperative bleeding caused reoperation in 378 patients (4.4%). There were 3.2% reoperations in 1994. The internal mammary artery or its bed was the main cause of the bleeding in 43%. The reoperations were performed earlier and emergent reoperations because of cardiac tamponade were less common during 1990-1994 than during 1970-1989. Reoperation for bleeding was required in 8.6% of patients 80 years of age and older. Combined coronary bypass surgery and intracardiac repair implied a 1.7 higher risk of reoperation for bleeding compared with patients undergoing primary isolated bypass surgery. Logistic regression analysis predicted old age, combined procedure, early year of surgery and use of the internal mammary artery as risk factors of reoperation for bleeding. The risk of reoperation was not significantly related to number of grafts inserted or if the patient had undergone previous cardiac surgery. Reoperation for bleeding increased the stay in intensive care by at least one day but did not increase the risk of wound infection. CONCLUSIONS: Special precautions seem indicated to reduce the risk of reoperation for bleeding in particularly elderly patients undergoing combined coronary surgery and other intracardiac repair.

Resection of a giant left main stem coronary artery aneurysm.

A 2 cm in diameter aneurysm of the left main stem was diagnosed in 1979. The aneurysm increased to 10 cm in diameter during 20 years. It was resected and successful bypass surgery was performed. No previous report was found of a giant true aneurysm involving the left main stem.

Combined repair of adult coarctation of the aorta and aortic valvular stenosis.

A 57-year-old man with a high-grade aortic stenosis and aortic coarctation was treated with concomitant valve replacement and insertion of a conduit from the ascending aorta to the retrocardiac descending aorta via the left pleura. Because heart failure has been reported shortly after cardiopulmonary bypass using this technique, the conduit was initially clamped until the postrepair haemodynamics was stable. Computed tomography after 14 months verified patency of the shunt.

[Neurological complications after open heart surgery. Risk factors identified in a retrospective study]. / Neurologiska komplikationer efter öppen hjärtkirurgi. Riskfaktorer identifierade i retrospektiv studie.

Cerebral complications were documented in 2 per cent (133/6666) of open heart procedures performed in adults at the Karolinska hospital, during the 7-year period, 1990-96. In 32 per cent (42/133) of cases, the neurological symptoms appeared after an uneventful postoperative interval of 2-14 (median 3) days. These patients were older and were characterised by a tendency toward a greater prevalence of carotid artery disease and of postoperative atrial arrhythmia. By contrast, the subgroup whose cerebral symptoms occurred immediately after the operation was characterised by greater severity of the symptoms, long operation time, and poor preoperative left ventricular function. Aggressive postoperative anticoagulant treatment, especially in patients with supraventricular arrhythmias, would seem to be justified to reduce the risk of neurological complications.