Distal aortic pressure during coarctation operation

Aortic Coarctation: Anesthetic Considerations

Aortic coarctation is a congenital narrowing of the descend ing thoracic aorta at or near the connection of the ductus arteriosus. It is the sixth most common congenital heart disease in the pediatric age group and constitutes 8% of congenital heart anomalies. Delivering anesthesia care to children undergoing coarctation repair is challenging be cause the anesthetist and the surgeon do not have the immediate safety net provided by cardiopulmonary bypass. Once the aorta is cross-clamped and the repair begins, the anesthesiologist is at the mercy of the surgeon's technical skill and speed and the child's ability to tolerate aortic cross- clamping. This article addresses the etiology and morphol ogy of this lesion. In addition, the perioperative anesthetic management principles relating to coarctation repair are discussed.

Selective use of left heart bypass for aortic coarctation

BACKGROUND

We evaluated left heart bypass (LHB) for spinal cord protection during aortic coarctation repair in patients with mild (primary, postsurgical, or intervention) and complex coarctation.

METHODS

Between 1990 and 2008, 19 patients (mean age, 21 years; weight, 70 +/- 16 kg) using LHB were compared with 27 patients (mean age, 16 years; weight, 65 +/- 8 kg) undergoing coarctation repair without LHB (non-LHB). Follow-up was similar (LHB, 5 +/- 4 vs non-LHB 4 +/- 3 years; p = 0.81).

RESULTS

Cohorts were similar in age and body surface area. No non-LHB patient lost somatosensory evoked potential or had a femoral artery pressure below 45 mm Hg with test clamping. LHB more often allowed graft interposition (18 of 19 [95%] vs non-LHB, 7 of 27 [26%]; p < 0.003) and a longer clamp time (LHB 44 +/- 16 vs non-LHB 31 +/- 12 minutes p < 0.003) without spinal cord ischemia. Two non-LHB patients had temporary spinal cord paresis. No early or late deaths occurred. Reintervention (LHB, 2 of 19 [11%] vs non-LHB, 2 of 27 [7%]; p = 0.82) and antihypertensive requirements were similar (LHB, 9 of 19 [40%] vs non-LHB, 8 of 27 [30%]; p = 0.35). The late peak transcoarctation gradient was 8 +/- 6 mm Hg in the LBH cohort vs 18 +/- 11 mm Hg in non-LBH patients (p= 0.001).

CONCLUSIONS

Although the adequacy of spinal cord collateral assessment in coarctation repair is imperfect, no spinal cord ischemia occurred with coarctation repair and LHB. We recommend LHB in patients with mild or complex coarctation.

Surgical experience of coarctation of the aorta in infants and young children

We evaluated the effectiveness of surgical treatment for coarctation of the aorta in infants and young children, based on our experience over 7 years. From March 1999 to December 2005, 168 cases of coarctation of the aorta in patients aged 21 days to 3 years were treated by end-to-end, extended end-to-end, or extended end-to-side ascending aorta and aortic arch anastomosis. The mortality rate was 0.6%. In 138 (82%) patients, the pressure in the lower extremity was higher than in the upper extremity. During 6-24 months of follow-up, hoarseness appeared in 6 patients. Echocardiography revealed stenosis of the end-to-end anastomosis in only 2 patients. We suggest that the best option for surgical treatment of coarctation of the aorta with associated cardiac malformations is a one-stage procedure using a median sternotomy approach. It is better to perform extended end-to-end anastomosis or anastomosis between the distal descending aorta and the left wall of the ascending aorta, or to extend this anastomosis to the transverse arch.

Use of partial cardiopulmonary bypass for coarctation repair through a left thoracotomy in children without collaterals

BACKGROUND

Paraplegia is a devastating complication of coarctation of the aorta (COA) repair. Since 1990 we have used left atrium-to-descending aorta cardiopulmonary bypass (CPB) for COA repair in patients with inadequate collaterals. We reviewed the results with that strategy and compared this CPB group with COA repairs in which CPB was not used to see whether there was any increase in morbidity or delay in recovery.

METHODS

From 1990 to 2006, 11 patients with COA were identified to have inadequate collaterals based on preoperative examination and intraoperative arterial monitoring and test clamp. Left thoracotomy with left atrium-to-descending aorta CPB was used in all. Age ranged from 4.2 to 17.4 years (mean, 8.7 +/- 4.6 years). Two were reoperations for recurrent COA, 3 patients had four prior transcatheter balloon dilatations. One patient had aberrant origin of the right subclavian artery. Operative techniques included resection with extended end-to-end anastomosis (n = 6), interposition graft (n = 4), and patch repair (n = 1). During the same period 71 patients older than 1 year of age had COA repair without CPB. Age ranged from 1.1 to 46.1 years (mean, 7.6 +/- 7.1 years; p = 0.6).

RESULTS

Preoperative imaging of CPB patients demonstrated absence of collaterals (n = 7), possible collaterals (n = 2), small collaterals (n = 1), and anomalous origin of the right subclavian artery (n = 1). Preoperative arm leg gradient in CPB patients was 36.0 +/- 9.0 mm Hg versus 49.9 +/- 15 mm Hg in non-CPB patients (p < 0.01). Mean distal femoral artery pressure with aortic test clamp was 34.3 +/- 4.8 mm Hg in CPB patients versus 49.8 +/- 12.4 mm Hg in non-CPB patients (p < 0.01). Mean CPB flow was 53% +/- 7.3% of calculated total flow. Cardiopulmonary bypass time ranged from 17 to 46 minutes (mean, 27.5 +/- 9.7 minutes). Aortic clamp time in CPB patients ranged from 15 to 33 minutes (mean, 21.6 +/- 6.3 minutes). In the non-CPB group aortic clamp time ranged from 10 to 50 minutes (mean, 23.4 +/- 7.5 minutes; p = 0.5). In the CPB group length of stay ranged from 3 to 7 days (mean, 4.9 +/- 1.3 days), and in the non-CPB group length of stay ranged from 3 to 12 days (mean, 4.7 +/- 1.4 days; p = 0.5). No patient had a neurologic complication. There were no other major complications in the CPB group (eg, bleeding, recurrent laryngeal nerve injury, re-COA).

CONCLUSIONS

Preoperative imaging and a lower arm-to-leg gradient in this series of COA patients suggested inadequate collateral circulation with the potential need for CPB. A femoral artery pressure of less than 45 mm Hg during test clamp was used as an indication for partial CPB. The use of left atrium-to-descending aorta CPB with just over 50% calculated total flow protected the spinal cord in a safe and expeditious fashion. Use of left heart bypass did not affect morbidity or recovery time as compared with COA repair in non-CPB patients.

Near infrared spectroscopy monitoring during pediatric aortic coarctation repair

BACKGROUND

Near infrared spectroscopy (NIRS) measures regional tissue oxygenation continuously and noninvasively and may allow assessment of changes in regional perfusion in real time.

METHODS

We used NIRS monitoring to track real-time changes in regional oxygenation (rSO2) above and below the aortic cross-clamp in patients undergoing aortic coarctation repair and routinely stored these data in an operative electronic data base. This allowed us to analyze the changes in rSO2 during aortic coarctation repair for three pediatric age groups (neonates, infants <1 year, and children >1 year). Two site [cerebral (rSO2-C) and somatic thoracodorsal (rSO2-S)] rSO2 monitoring was performed in patients undergoing aortic coarctation repair. Data for rSO2 were analyzed across sites and age groups before, during and after cross-clamp.

RESULTS

Twenty-six patients were available for analysis (11 neonates, 5 infants and 10 children). The regional oxygenation below the cross clamp (rSO2-S) declined significantly in all three age groups, but the decrease in neonates and infants <1 year of age was significantly greater than in the older children.

CONCLUSIONS

Monitoring rSO2-S provides real-time trend information of regional oxygenation below the aortic cross-clamp. The decline in rSO2-S during aortic cross-clamp was rapid and large in most neonates and young infants <1 year which suggests impairment of regional perfusion presumably because of a lack of adequate collateral circulation to the monitored regional tissue. In contrast, the rSO2-S changed only to a minor degree in most infants and children >1 year, possibly because they had time to develop a more adequate collateral circulation around incomplete aortic obstruction.

Somatosensory-evoked potentials during aortic coarctation repair

OBJECTIVE

To determine the incidence of somatosensory-evoked potential (SSEP) changes and the interventions based on these changes during aortic coarctation repair.

DESIGN

Retrospective review.

SETTING

Single-institution, university hospital.

PARTICIPANTS

Eighty-four children who had undergone surgical repair of aortic coarctation from January 1984 to May 1996.

INTERVENTIONS

SSEPs were monitored in all patients throughout the procedure. A persistent decrease in amplitude greater than 50% from baseline was considered significant. Duration of SSEP changes in relation to the time course of surgical repair and whether a surgical or anesthetic intervention resulted from a change in SSEPs were documented.

MEASUREMENTS AND MAIN RESULTS

Eighty-four patients underwent 87 surgical procedures. SSEP changes occurred in 40% of the procedures: 38.5% with repair and 15% with test clamp, with 9% occurring during both test clamp and repair. Interventions, which included repositioning the aortic cross-clamp, elevating blood pressure, and aborting surgery, occurred in 26.4% of all procedures based on SSEP changes. No patient sustained a neurologic deficit.

CONCLUSION

This is the largest series to date describing the use of SSEPs in aortic coarctation repair. These SSEP changes were often immediately amenable to changes in surgical and anesthetic management. SSEP changes and interventions based on these changes occurred with a considerable frequency.

Partial left heart bypass with centrifugal pump and limited anticoagulation during the resection of coarctation of the aorta

Resection of coarctation of the aorta necessitates crossclamping of the descending aorta. Despite the existence of a collateral circulation, spinal cord ischaemia and intestinal ischaemia may occur associated with a prolonged crossclamp time and distal hypoperfusion during the operation. To prevent these severe complications and to control hypertension proximal to the clamp, circulatory support may be necessary.

We performed partial left heart bypass (PLHB) with limited anticoagulation in four patients, using a centrifugal pump in orderto sustain a mean arterial blood pressure of at least 60mmHg in the distal thoracic aorta below the clamped coarctated segment. The method is practical, simple and safe. It combines features of several methods of protection of the spinal cord: adequate distal perfusion of the aorta at a desired flow rate and blood pressure, avoidance of proximal hypertension, minimal aortic and cardiac manipulation and avoidance of bleeding tendency by limited heparinization. Vasodilating drugs with their adverse effect on distal aortic pressure are not necessary in this situation.

Postoperatively, neurological sequelae orvital organ damage did not occur in our patients.