Cerebral oxygen balance is impaired during repair of aortic coarctation in infants and children

Risk Factors of Perioperative Brain Injury in Children Under Two Years Undergoing Coarctation Repair

BACKGROUND

To investigate clinical manifestations and factors of perioperative brain injury (PBI) after surgical repair of coarctation of the aorta (CoA) combined with other heart malformations under cardiopulmonary bypass (CPB) in children under two years.

METHODS

The clinical data of 100 children undergoing CoA repair were retrospectively reviewed between January 2010 and September 2021. Univariate and multivariate analyses were performed to identify factors of PBI development. Hierarchical and K-means cluster analyses were conducted to evaluate the association between hemodynamic instability and PBI.

RESULTS

Eight children developed postoperative complications, and all of them had a favorable neurological outcome one year after surgery. Univariate analysis revealed eight risk factors associated with PBI. Multivariate analysis indicated operation duration (P = 0.04, odds ratio [OR], 2.93; 95% confidence interval [CI], 1.04 to 8.28) and pulse pressure (PP) minimum (P = 0.01; OR, 0.22; 95% CI, 0.06 to 0.76) were independently associated with PBI. The following three parameters emerged for cluster analysis: PP minimum, mean arterial pressure (MAP) dispersion, and systemic vascular resistance (SVR) average. Using cluster analysis, PBI mainly occurred in subgroups 1 (12%, three of 26) and 2 (10%, five of 48). The mean value of PP and MAP in subgroup 1 was significantly higher than in subgroup 2. The mean SVR in subgroup 1 was the highest. The lowest PP minimum, MAP, and SVR were observed in subgroup 2.

CONCLUSION

Lower PP minimum and longer operation duration were independent risk factors for developing PBI in children under two years during CoA repair. Unstable hemodynamics should be avoided during CPB.

Preoperative Aortic Arch Size and Late Outcome After Coarctation Repair by Lateral Thoracotomy

BACKGROUND

The approach (lateral thoracotomy versus median sternotomy) to repair coarctation of the aorta is frequently based on arch dimensions from the preoperative echocardiogram. Few studies have assessed the relationship between preoperative arch dimensions and late postoperative outcome. This study aimed to define how preoperative arch dimensions relate to late outcomes and identify long-term predictors of a successful operation.

METHODS

We performed a retrospective review of 102 neonates and infants undergoing isolated coarctation repair by lateral thoracotomy between 2003 and 2012. Long-term surgical success was defined based on the following five factors: corrected arch gradient below 20 mm Hg, blood pressure cuff gradient below 15 mm Hg, systolic blood pressure below the 95th percentile during the clinic visit, no antihypertensive medication use, and freedom from reintervention. Regression analysis was performed to identify factors that would predict the need for reintervention and long-term success.

RESULTS

At a median of 6 years of follow-up, long-term success was achieved in 63% (56 of 89) of patients, and 94% (96 of 102) were free of reintervention. Bivariate analysis showed that patients requiring reintervention had smaller absolute isthmus dimension (p = 0.04). No significant predictors for reintervention or long-term success could be identified, although a larger distal transverse arch dimension may play a role in long-term success (hazard ratio, 0.7; 95% confidence interval, 0.05 to 1.0; p = 0.06).

CONCLUSIONS

Aortic arches of various dimensions were successfully repaired by lateral thoracotomy. No significant predictors for reintervention or long-term success could be identified, although the distal transverse arch dimension may play a role in long-term success.

Test-retest reliability of brain mitochondrial cytochrome-c-oxidase assessed by functional near-infrared spectroscopy

Functional near-infrared spectroscopy (fNIRS) is a noninvasive method for measuring in vivo both hemodynamic and mitochondrial metabolic activities in brain cortical structures. Although the test-retest reliability of the hemodynamic measures, such as reflected by oxygenated (HbO2), deoxygenated (HHb) hemoglobin, and the tissue oxygenation index (TOI), has been previously reported to be good to excellent, the reliability of the metabolic signal indexed by oxidized cytochrome-c-oxidase (oxCCO) has not been reported. The present test-retest study compared the reliability of the metabolic and hemodynamic signals in 10 healthy participants undergoing hypo- and hypercapnia challenges. The primary reliability measure was the intraclass correlation coefficient (ICC). Results of both hypo- and hypercapnia showed that the oxCCO signal (ICC  =  0.876  /  0.757) had robust reliability comparable with that of the HbO2 (ICC  =  0.841  /  0.801), HHb (ICC  =  0.804  /  0.571), and TOI (ICC  =  0.574  /  0.614) signals. These findings show that the oxCCO signal can be assessed by fNIRS with comparable reliability to the hemodynamic measures. We discuss the results in light of current interest in a mitochondrial metabolic marker derived from fNIRS.

Sodium nitroprusside in 2014: A clinical concepts review

Sodium nitroprusside has been used in clinical practice as an arterial and venous vasodilator for 40 years. This prodrug reacts with physiologic sulfhydryl groups to release nitric oxide, causing rapid vasodilation, and acutely lowering blood pressure. It is used clinically in cardiac surgery, hypertensive crises, heart failure, vascular surgery, pediatric surgery, and other acute hemodynamic applications. In some practices, newer agents have replaced nitroprusside, either because they are more effective or because they have a more favorable side-effect profile. However, valid and adequately-powered efficacy studies are sparse and do not identify a superior agent for all indications. The cyanide anion release concurrent with nitroprusside administration is associated with potential cyanide accumulation and severe toxicity. Agents to ameliorate the untoward effects of cyanide are limited by various problems in their practicality and effectiveness. A new orally bioavailable antidote is sodium sulfanegen, which shows promise in reversing this toxicity. The unique effectiveness of nitroprusside as a titratable agent capable of rapid blood pressure control will likely maintain its utilization in clinical practice for the foreseeable future. Additional research will refine and perhaps expand indications for nitroprusside, while parallel investigation continues to develop effective antidotes for cyanide poisoning.

Stage II palliation of hypoplastic left heart syndrome without cardiopulmonary bypass

OBJECTIVES

Bidirectional cavopulmonary anastomosis has been performed without cardiopulmonary bypass for some single-ventricle heart defects. Limited data are available for the outcomes of off-pump bidirectional cavopulmonary anastomosis in infants with hypoplastic left heart syndrome. The purpose of this study is to determine the early outcomes for stage II palliation of hypoplastic left heart syndrome without cardiopulmonary bypass.

METHODS

This is a retrospective review of infants having surgical palliation of hypoplastic left heart syndrome from April 2003 to March 2010 at a single institution.

RESULTS

Seventy-five infants had a modified Norwood procedure, 65 with a right ventricle-pulmonary artery conduit, 10 with an aortopulmonary shunt, 2 with atrioventricular valve repair, and 3 with extracorporeal life support. Sixty-eight patients had hypoplastic left heart syndrome or one of its variants, and 7 had other single-ventricle lesions. There were 2 stage I deaths. Stage I survival was 97% (95% confidence interval, 88%-99%). Another 5 infants succumbed in the interstage period. Of the 68 stage I and interstage survivors, 61 had bidirectional cavopulmonary anastomoses, 20 without cardiopulmonary bypass. Median age was 6 months (range, 4-13 months), and median weight was 6.1 kg (range, 5.2-9.0 kg). There were no conversions to cardiopulmonary bypass when off-pump bidirectional cavopulmonary anastomosis was attempted. There were no hospital deaths. Median ventilation duration was 10 hours (range, 6-18 hours), and length of stay was 5 days (range, 4-9 days). Follow-up was available on all infants at a median duration of 17 months (range, 3-43 months), with no unplanned reinterventions.

CONCLUSIONS

Bidirectional cavopulmonary anastomosis without the use of cardiopulmonary bypass can be performed safely and with low mortality for selected infants with hypoplastic left heart syndrome. Midterm to long-term outcomes remain to be determined.

Higher cerebral oxygen saturation may provide higher urinary output during continuous regional cerebral perfusion

Objective

We examined the hypothesis that higher cerebral oxygen saturation (rSO₂) during RCP is correlated with urinary output.

Methods

Between December 2002 and August 2006, 12 patients aged 3 to 61 days and weighing 2.6 to 3.4 kg underwent aortic arch repair with RCP. Urinary output and rSO₂ were analyzed retrospectively. Data were assigned to either of 2 groups according to their corresponding rSO₂: Group A (rSO₂ ≦ 75%) and Group B (rSO₂ < 75%).

Results

Seven and 5 patients were assigned to Group A and Group B, respectively.

Group A was characterized by mean radial arterial pressure (37.9 ± 9.6 vs 45.8 ± 7.8 mmHg; P = 0.14) and femoral arterial pressure (6.7 ± 6.1 vs 20.8 ± 14.6 mmHg; P = 0.09) compared to Group B. However, higher urinary output during CPB (1.03 ± 1.18 vs 0.10 ± 0.15 ml·kg^-1·h^-1; P = 0.03). Furthermore our results indicate that a higher dose of Chlorpromazine was used in Group A (2.9 ± 1.4 vs 1.7 ± 1.0 mg/kg; P = 0.03).

Conclusion

Higher cerebral oxygenation may provide higher urinary output due to higher renal blood flow through collateral circulation.

Regional and central venous oxygen saturation monitoring following pediatric cardiac surgery: concordance and association with clinical variables

OBJECTIVE

To compare changes in regional cerebral or flank oxygen saturation measured by near-infrared spectroscopy with changes in central venous oxygen saturation (ScvO2) and to determine clinical variables associated with these changes.

DESIGN

Prospective observational cohort study.

SETTING

University tertiary care center, pediatric cardiac intensive care unit.

PATIENTS

Seventy postoperative congenital cardiac surgical patients (median age 0.3 yrs; interquartile range 0.02-0.46 yrs).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured temporally correlated regional oxygen saturation (rSO2) with hematologic (hematocrit), biochemical (arterial blood gas, ScvO2, and lactate) and physiologic (temperature, heart rate, mean blood pressure, and pulse oximetry) variables in the first postoperative day. Cerebral and flank rSO2 were strongly correlated with ScvO2, in both cyanotic or acyanotic patients and single- or two-ventricle physiology with and without aortic arch obstruction (all p < .001). However, individual values had wide limits of agreement on Bland-Altman analysis. The correlations of change in these measurements were weaker but still significant (all p < .0001), again with wide limits of agreement. Similar direction of change in cerebral rSO2 and ScvO2 was present 64% (95% confidence interval, 55-73%) of the time. Change in arterial pressure of carbon dioxide (delta PaCO2) was associated with cerebral delta rSO2 (delta PaCO2 beta = 0.35, p < .0001) but not flank delta rSO2 or delta ScvO2. A pattern of relative cerebral desaturation (flank rSO2 > cerebral rSO2) was noted in a majority of patients (81%) with two-site monitoring regardless of bypass method or age.

CONCLUSIONS

Neither individual values nor changes in rSO2 are interchangeable measures of ScvO2 in postoperative pediatric cardiac patients. The unique relationship between changes in PaCO2 and cerebral rSO2 supports the hypothesis that cerebral near-infrared spectroscopy monitors regional cerebral oxygenation. Clinical application of this monitor must include recognition of the clinical variables that affect regional brain oxygenation.

Temporal and Anatomic Risk Profile of Brain Injury With Neonatal Repair of Congenital Heart Defects

BACKGROUND AND PURPOSE

Brain injury is common in newborns with congenital heart disease (CHD) requiring neonatal surgery. The purpose of this study is to define the risk factors for preoperative and postoperative brain injuries and their association with functional cardiac anatomic groups.

METHODS

Sixty-two neonates with CHD were studied with preoperative MRI, and 53 received postoperative scans. Clinical and therapeutic characteristics were compared in newborns with and without newly acquired brain injuries. A subset of 16 consecutive patients was monitored with intraoperative cerebral near-infrared spectroscopy.

RESULTS

Brain injury was observed in 56% of patients. Preoperative brain injury, seen in 39%, was most commonly stroke and was associated with balloon atrial septostomy (P=0.002). Postoperative brain injury, seen in 35%, was most commonly white matter injury and was particularly common in neonates with single-ventricle physiology and aortic arch obstruction (P=0.001). Risk factors associated with acquired postoperative brain injury included cardiopulmonary bypass (CPB) with regional cerebral perfusion (P=0.01) and lower intraoperative cerebral hemoglobin oxygen saturation during the myocardial ischemic period of CPB (P=0.008). In a multivariable model, new postoperative white matter injury was specifically associated with low mean blood pressure during the first postoperative day (P=0.04).

CONCLUSIONS

Specific modifiable risk factors can be identified for preoperative and postoperative white matter injury and stroke associated with neonatal surgery for CHD. The high incidence of postoperative injury observed despite new methodologies of CPB indicates the need for ongoing evaluation to optimize neurological outcome.

Surgery is the best treatment for primary coarctation in the majority of cases

Today, the availability of competing techniques for coarctation repair, including numerous surgical approaches as well as interventional ones, raises important questions about indications, risks and criteria for procedural success. Surgical treatment of coarctation is an extremely well tolerated procedure with excellent long-term efficacy due to an 88 to 96% 5 years freedom from re-intervention in patients operated on within the first months of life. If compared with surgery, balloon angioplasty features a higher risk for aneurysm formation, aortic rupture and a lower degree of success, with potentially important residual pressure gradient in up to 20.7% of patients. Stents are believed to overcome the problems of simple dilation, but concerns remain about the materials and the potential of re-expandibility in view of the growth of the treated aorta. Moreover, serious complications, including death, have been reported by stent implantation as well, similar to aneurysms or dissections (4.3%), balloon rupture with stent migration or cerebral vascular injury (9%). There is no evidence to date for the superiority of any interventional approach to surgical treatment of primary coarctation. The favorable long-term surgical results outweigh the proposed short-term benefits of angioplasty and stenting, which should be restricted to well selected cases.

Neonatal aortic arch surgery

Surgical repair of the aortic arch is entailed in the neonatal period of patients with: hypoplastic left heart syndrome, interrupted aortic arch, hypoplastic aortic arch and complex aortic coarctation. Aortic arch surgery requires a period of circulatory arrest and deep hypothermia. Cerebral selective perfusion has recently been introduced as an alternative to circulatory arrest with the aim of reducing mortality and neurological complications. Moreover, the arch reconstruction phase can be safely performed under moderate hypothermia and with cerebral and myocardial perfusion (on beating heart), thus, completely avoiding cerebral ischemia and completely avoiding or drastically reducing myocardial ischemia.