Surgical technique to avoid circulatory arrest and direct arch vessel cannulation during neonatal aortic arch reconstruction.

Deep hypothermic circulatory arrest (DHCA) has been used routinely for surgery involving the aortic arch. Recently, techniques have been developed that avoid circulatory arrest and maintain low-flow cerebral perfusion (LFCP) in an attempt to avoid the potential neurological sequelae associated with DHCA. We describe a technique of LFCP that avoids circulatory arrest and direct cannulation of the arch vessels. Five patients underwent reconstruction of the aortic arch with concomitant biventricular intracardiac repair. The distal ascending aorta was cannulated and patients were systemically cooled. The cannula was advanced into the innominate artery and snared in place prior to opening and reconstructing the aorta with continuous LFCP. In all five patients, we completely avoided circulatory arrest and direct cannulation of the arch vessels. All patients survived and there were no adverse neurological outcomes.     

Aortic arch reconstruction without circulatory arrest: Review of techniques,applications, and indications

The majority of neonatal intracardiac repairs can now be performed with the use of low-flow cardiopulmonary bypass. However, aortic arch reconstruction still requires a period of circulatory arrest. Recently, a number of surgeons have reported techniques of limiting or completely avoiding circulatory arrest during arch reconstruction in an attempt to reduce the risk of neurologic injury. Several techniques are currently in use that have been successfully applied during biventricular repair and the Norwood operation for a wide range of aortic arch pathology including hypoplastic or interrupted aortic arch, the hypoplastic left heart syndrome, and its equivalents. These techniques maintain continuous low-flow cerebral perfusion via the innominate artery, directly or indirectly. In the last 2 years at the Montreal Children's Hospital (Montreal, Canada) we have consistently used such techniques for all arch reconstructions, including the Norwood operation, completely avoiding the use of circulatory arrest. These techniques are still in evolution with regard to flow rates, temperature, and safe period of low flow. Although the early results are encouraging, long-term follow-up with respect to neurodevelopmental outcome is essential to help us decide which techniques are optimal. This chapter provides an overview of the currently used techniques allowing cerebral perfusion during aortic arch reconstruction and summarizes our early experience at the Montreal Children's Hospital. Copyright © 2002 by W.B. Saunders Company     

Central arterial cannulation and the arch first method for aortic arch aneurysm repair.

BACKGROUND: We investigated whether the axillary artery or ascending aorta cannulation combined with the arch first method decreases the risk of stroke during total arch replacement. PATIENTS AND METHODS: From January 2002 to January 2006, 35 total arch replacements were performed with the arch first method and central arterial cannulation. The mean age was 66+/-10 years. The cannulation sites were the axillary artery in 19 and the ascending aorta in 16. The arch first method (a short period of deep hypothermic circulatory arrest with retrograde cerebral perfusion and then subsequent antegrade cerebral perfusion) was used in all patients. RESULTS: The mean retrograde cerebral perfusion time was 29+/-7 min. The incidence of the permanent neurological dysfunction related to the surgical procedures was 2.9% (1/35). Hospital mortality was 5.7% of patients (2/35). There was no difference in the operative outcome between the 2 arterial inflow sites. CONCLUSION: At the time of total arch replacement, the use of central arterial cannulation and the arch first method are effective methods for preventing permanent brain injury. Cannulation of the ascending aortic using Dispersion cannula perfusing toward the aortic valve is considered to be a safe and favorable method for central arterial cannulation.     

Decreased cerebral emboli during distal aortic arch cannulation: a randomized clinical trial.

BACKGROUND: Cerebral emboli occur during cardiopulmonary bypass and are a principal cause of postoperative neurologic dysfunction. We hypothesized that arterial cannulation of the distal aortic arch, with placement of the cannula tip beyond the left subclavian artery, will result in fewer cerebral microemboli than conventional cannulation of the ascending aorta. METHODS: Patients undergoing coronary bypass surgery with a single crossclamp technique were randomized to receive cannulation of the distal aortic arch (n = 17) or standard cannulation of the ascending aorta (control group, n = 17). Trendelenburg positioning was used whenever possible. Cerebral emboli were quantified by continuous transcranial Doppler monitoring of the middle cerebral artery. RESULTS: Baseline demographics were similar for the 2 groups of patients, including cardiopulmonary bypass and crossclamp times. Cerebral microemboli were detected during cardiopulmonary bypass in all patients, with a range of 17 to 627 emboli. The total number of detected emboli was lower in the arch cannulation group (152 +/- 33, mean +/- standard error of the mean) than in the conventional cannulation group (249 +/- 35, P =.04). Embolization rates were lower in distal arch patients than in control patients during cardiopulmonary bypass (2.0 +/- 0.3 vs 4.2 +/- 0.9 per minute, respectively, P =.03). Reduction in cerebral emboli by distal arch cannulation was most pronounced during perfusionist interventions. CONCLUSIONS: Cannulation of the distal aortic arch results in less cerebral microembolism than conventional cannulation of the ascending aorta. Provided it is performed safely, distal arch cannulation may be an important surgical option for patients with severe atherosclerosis of the ascending aorta.     

Arch reconstruction without circulatory arrest: Scientific basis for continued use and application to patients with arch anomalies

Aortic arch hypoplasia is a common constituent of congenital heart disease. While repair of these lesions has been performed routinely during deep hypothermia and circulatory arrest, new approaches are emerging. One such approach, regional low-flow perfusion, will be described here. This technique exploits the anticipated modified Blalock-Taussig shunt as a perfusion conduit. With control of the brachiocephalic vessels and the descending thoracic aorta, circulatory support can be provided to the neonate with exposure identical to that obtained by circulatory arrest. While first applied to children undergoing the Norwood operation for hypoplastic left heart syndrome, this technique has recently been applied to children requiring complex arch surgery in the setting of biventricular repair. To date, 36 neonates requiring arch reconstruction (27 Norwood operations, 9 biventricular repairs) have been supported with regional low-flow perfusion. Thirty-day and hospital discharge survival has been 74% (20/27) for neonates undergoing Norwood operation, and 88% (8/9) for those undergoing biventricular repair. We will review the operative technique, methodologies, and clinical studies that led us to conclude that regional low-flow perfusion provides cerebral, as well as somatic, circulatory support to the neonate undergoing arch reconstruction. Copyright © 2002 by W.B. Saunders Company     

Single-stage repair of aortic coarctation with ventricular septal defect using isolated cerebral and myocardial perfusion.

OBJECTIVE: To avoid hypothermic circulatory arrest, we have repaired aortic coarctation with ventricular septal defect (VSD) in a one-stage procedure using an isolated cerebral and myocardial perfusion technique, and retrospectively compared this novel approach to the conventional two-stage approach. METHODS: Between October 1991 and February 1999, 24 infants, aged 4-137 days (median, 27 days) and weighing 1.7-4.3 kg (median, 3.0 kg), underwent the repair of aortic coarctation with VSD either in one (group I, n=11) or two stages (group II, n=13). In Group I, an arterial cannula for cardiopulmonary bypass was inserted into the ascending aorta in six patients with coarctation only, or into a polytetrafluoroethylene (PTFE) graft which was anastomosed to the innominate artery in the remaining five who had hypoplastic arches. A cross-clamp was placed between the innominate and left carotid arteries. The bypass flow was reduced to 30-50% of full flow at 28 degrees C, thereby maintaining a radial artery pressure of 30-45 mmHg. At this point, the aortic coarctation was repaired by an end-to-end arch anastomosis, while maintaining brain perfusion and with the heart still beating. In five patients with hypoplastic aortic arches, the innominate artery proximal to the graft was then secured down and the arch anastomosis was extended to the distal ascending aorta, while providing isolated cerebral perfusion and cardioplegic arrest. After arch reconstruction was performed, the clamp was moved onto the ascending aorta, and the VSD was closed with systemic perfusion. In contrast, for group II patients, coarctation repairs were performed through a posterolateral approach, and existing VSDs were closed as secondary procedures. RESULTS: The mean isolated cerebral and myocardial perfusion time for group I was 13 min (range, 7-20 min). The myocardial ischemic time did not differ between groups I and II (43+/-4 vs. 42+/-5 min, not significant). There were no hospital mortalities or neurological complications in either group, but one late death in each group. CONCLUSION: Single-stage repair of aortic coarctation with VSD does not increase myocardial ischemic time compared to the traditional two-stage approach. The isolated cerebral and myocardial perfusion technique may offer substantial brain and myocardial protection during aortic arch reconstruction.     

Regional low-flow perfusion provides somatic circulatory support during neonatal aortic arch surgery

BACKGROUND: Regional low-flow perfusion has been shown to provide cerebral circulatory support during neonatal aortic arch operations. However, its ability to provide somatic circulatory support remains unknown. METHODS: Fifteen neonates undergoing arch reconstruction with regional perfusion were studied. Three techniques were used to assess somatic perfusion: abdominal aortic blood pressure, quadriceps blood flow (near-infrared spectroscopy), and gastric tonometry. RESULTS: Twelve patients required operation for hypoplastic left heart syndrome, and 3 required arch reconstruction with a biventricular repair. There was one death (7%). Abdominal aortic blood pressure was higher (12+/-3 mm Hg versus 0+/-0 mm Hg), and quadriceps blood volumes (5+/-24 versus -17+/-26) and oxygen saturations (57+/-25 versus 33+/-12) were greater during regional perfusion than during deep hypothermic circulatory arrest (p < 0.05). During rewarming, the arterial-gastric mucosal carbon dioxide tension difference was lower after circulatory arrest than after regional perfusion (-3.3+/-0.3 mm Hg versus 7.8+/-7.6 mm Hg, p < 0.05). CONCLUSIONS: Regional low-flow perfusion provides somatic circulatory support during neonatal arch surgical procedures. Support of the subdiaphragmatic viscera should improve the ability of neonates to survive the postoperative period.     

Techniques of aortic arch replacement: profound hypothermia versus moderate hypothermia with innominate artery perfusion

Aortic arch resection remains a challenging problem. At present, the most reliable technique appears to be profound hypothermia and circulatory arrest, although long cardiopulmonary bypass times and coagulopathy remain significant problems. Interest in alternative procedures continues. Herein, we report our experience of aortic arch replacement in eight patients using profound hypothermia (12 to 17 degrees C) and circulatory arrest in six patients (Group I) and moderate (20 degrees C) hypothermia with low flow (200 ml/min), pressure-monitored (100 mm Hg) innominate artery perfusion by way of a 14 Ga. cannula in 2 (Group II). Arch repair was by patch graft in two, and tube graft in six. Concomitant ascending aortic replacement was performed in five, aortic valve replacement in four, and coronary bypass in two. Circulatory arrest times ranged from 15 to 71 minutes in Group I and were 15 minutes and 35 minutes in Group II. All patients survived. One patient in Group I had a neurologic injury of moderate severity, probably due to a hypoxic postoperative cardiac arrest. We have found low flow pressure-monitored innominate artery perfusion and moderate hypothermia to be simple and expedient, and we will continue use of this technique.     

Direct cannulation of the common carotid artery during the ascending aortic or aortic arch replacement

Objective: To evaluate cerebral perfusion using direct cannulation into the common carotid artery. A new technique is needed to protect brain ischemic injury during ascending aortic or aortic arch replacement. Methods: This technique was evaluated for patients who would have difficulty maintaining adequate cerebral perfusion during surgery. The procedure was performed when patients had the following diagnoses: pseudoaneurysm formation in contact with the sternum with the risk of aneurysmal rupture (n=5), acute aortic dissection with compression of the true lumen of the innominate artery by the pseudolumen (n=3), or a large volume of thrombus in the lumen of the aneurysm with the risk of cerebral thromboembolism if standard extracorporeal circulation was used (n=2). The perfusion catheter was cannulated into one side of the common carotid artery (right side: n=6, left side: n=4) and mean perfusion flow rate was found to be 175 mL/min. The operative procedures consisted of ascending aortic and aortic arch replacement with coronary artery bypass grafting in six patients, ascending aortic replacement in 2 patients, and innominate artery reconstruction/innominate artery and right subclavian artery reconstruction in one patient. Results: No cerebral accidents or deaths occurred while patients were hospitalized. We have followed up patients for a mean of 2.1 years (maximum 3.6 years), with no complications noted from the surgical procedure. Conclusions: Direct cannulation of the common carotid artery is a simple, safe, and acceptable cerebral protection for patients undergoing aortic or aortic arch replacement procedures in the patients with these specific conditions.     

Aortic arch and proximal supraaortic arterial repair under continuous antegrade cerebral perfusion and moderate hypothermia.

PURPOSE: In this prospective study the clinical and neurological outcome of continuous antegrade cerebral perfusion (ACP) and moderate hypothermia was evaluated in patients undergoing ascending and aortic arch repair including reconstruction of the proximal supraaortic arteries. METHODS: In 50 consecutive patients (mean age 47 yr, range 22-70) aortic arch and supraaortic arterial repair was performed: ascending aorta and aortic arch (n=34) and aortic arch and Bentall procedure (n = 16). In 12 patients the distal anastomosis was performed using the elephant trunk technique. Test-clamping of the innominate artery for 3 min was performed under EEG-monitoring followed by the same procedure for the left carotid artery. Cardiopulmonary bypass was instituted and the innominate artery replaced by a polyester graft before antegrade perfusion was carried out through the graft. While cooling to 28-30 degrees C, the left carotid artery was similarly treated with subsequent antegrade cerebral perfusion. The distal anastomosis was made at or beyond the left subclavian artery under circulatory arrest. During rewarming the innominate and carotid polyester grafts as well as the subclavian artery were anastomosed to the main graft, while antegrade cerebral perfusion was continued. RESULTS: In 46 patients antegrade cerebral perfusion was achieved with a mean volume flow of 12 ml/kg/min and a mean arterial pressure of 54 mmHg. EEG-monitoring delineated stable and symmetrical recordings. In four patients antegrade flow (mean 15 ml/kg/min) and pressure (mean 65 mmHg) had to be increased to establish baseline EEG-recordings. The mean time of circulatory arrest was 18 min.The overall hospital mortality was 6%: two patients died from cerebral infarction and one patient suffered from a ruptured abdominal aortic aneurysm. Three patients (6%) developed a temporary neurological deficit which resolved spontaneously. Two patients (4%) developed renal failure requiring temporary hemodialysis. Pulmonary complications occurred in 12 patients (25%). CONCLUSION: Continuous antegrade cerebral perfusion via selective grafts to the innominate and carotid arteries offers adequate protection in patients undergoing replacement of the ascending aorta or aortic arch and great vessels. This technique allows radical repair and optimal vascular reconstruction without time restrains and avoids the necessity for profound hypothermia     

选择性脑灌注在小儿主动脉弓手术中的应用

目的为了减轻手术中的脑损伤,探讨选择性脑灌注（SCP）技术在小儿主动脉弓手术中应用的有效性和安全性。方法2007年4月至2008年5月上海儿童医学中心对32例小儿先天性心脏病患者施行主动脉弓手术中应用SCP技术;年龄8d～103个月（14．4±25．4个月）,体重2．7～22．0kg（6．7±4．4kg）,其中主动脉缩窄伴心内畸形22例,主动脉弓中断伴心内畸形10例。采用弹簧动脉插管,在升主动脉靠近无名动脉根部处插管,转流降温至肛温18～20℃,然后将动脉灌注管向上延伸插入无名动脉内进行SCP。结果SCP时间为17～121min（39．6±19．4min）,流量维持在15～40ml／（kg·min）[29．7±6．1ml／（kg·min）]。术后死亡4例,死亡原因为低心排血量或心律失常,均无脑损伤证据。生存28例患者在临床中均无明显神经系统并发症,术后25例患者做脑电图检查均无异常,5例新生儿患者做头颅B超和脑磁共振成像（MRI）检查未见异常。结论SCP是小儿主动脉弓手术中一种简单可行和安全有效的脑保护方法。     

Aortic arch reconstruction using regional perfusion without circulatory arrest.

OBJECTIVES: Deep hypothermic circulatory arrest during repair of aortic arch anomalies may induce neurological complications or myocardial injury. Regional cerebral and myocardial perfusion may eliminate those potential side effects. METHODS: From March 2000 to March 2002, 48 neonates or infants with complex arch anomaly were operated on using the regional perfusion technique. Thirty-three patients were male and the median age was 24 days (range 5-301 days). Preoperative diagnosis consisted of coarctation or interruption of the aorta associated with ventricular septal defect (group I, n = 26) and arch anomaly with complex intracardiac defects such as hypoplastic left heart syndrome or its variants (group II, n = 22). Arterial cannula was inserted through the innominate artery and the flow rate was regulated to about 50-100 ml/kg per min during regional perfusion. Simultaneous myocardial perfusion was maintained using a Y-connected infusion line. Cardioplegia was applied during intracardiac repair. RESULTS: Cardiopulmonary bypass and aortic cross-clamp times were 154 +/- 49 and 39 +/- 34 min, respectively. Temporary circulatory arrest for intracardiac procedures was performed in eight patients. However, the mean arrest time was minimized (range 1-18 min). The descending aorta clamping time was 33 +/- 16 min. Operative mortality rates in each group were 0 and 18.2% (0/26 and 4/22). Late mortality rates were 0 and 11.1% (0/26 and 2/18) during 9.1 months of follow-up. Complications consisted of low cardiac output in eight cases, transient neurological problems in two cases, and transient renal insufficiency in two cases, respectively. CONCLUSIONS: Regional perfusion is feasible and can be used with acceptable results. It may reduce potential complications following aortic arch reconstruction using circulatory arrest. However, repair of aortic arch in the patients with complex intracardiac defects still imposes a significant rate of mortality and morbidity.     

Simplified aortic cannulation (SAC) – a useful technique for neonates with small aortas

A simplified means of arterial cannulation for cardiopulmonary bypass in small neonates and those infants with diminutive aortas, or requiring reconstruction of the ascending aorta, is presented. It involves suturing a long 3.5 mm graft to the innominate artery and inserting the arterial cannula into the end of the graft. This technique improves exposure, thereby greatly simplifying many complex repairs, and may be used for initiation of ECMO or for hybrid procedures in the postoperative period.     

Cannulation of the innominate artery during surgery of the thoracic aorta: our experience in 55 patients.

BACKGROUND: Alternative cannulation sites such as the right/left axillary artery, the ascending aorta and aortic arch have been recently preferred to the femoral artery to improve neurologic outcome in patients undergoing surgery of the thoracic aorta. In 2004, we started to select the innominate artery as an arterial cannulation site for CPB and antegrade cerebral perfusion institution. Here we present our preliminary experience with 55 patients. METHODS: Between November 2004 and 2006, 55 patients (mean age 60+/-14 years) underwent surgery on the thoracic aorta using the innominate artery as a site for arterial cannulation. Indication for surgery was a degenerative aneurysm in 49 (89.1%), an acute type A dissection in 2 patients (3.6%), a post-dissection aneurysm in 3 (5.4%), a supravalvular aortic stenosis in 1 patient (1.8%). Operative procedure included total arch replacement (n=9), hemiarch replacement (n=6), ascending aorta replacement (n=21), Bentall procedure (n=18) and aortoplasty with patch (n=1). Mean CPB and cross clamp times were 131+/-60 and 95+/-29 min, respectively. Mean cerebral perfusion time was 54+/-26 min. RESULTS: The hospital mortality rate was 3.6%. There were no permanent neurologic dysfunction and one (1.8%) temporary neurological dysfunction. CONCLUSION: Our results with the cannulation of the innominate artery were encouraging. This provides the same advantages of the axillary artery cannulation with greater simplicity and avoiding extra surgical incisions which may be site for local complications. It may represent a valid option for CPB and antegrade cerebral perfusion institution in aortic procedures.     

Norwood operation without circulatory arrest: a new surgical technique

Circulatory arrest (CA) is associated with potential neurologic injury. We have developed a new surgical technique to eliminate CA during the Norwood operation. A modified Blalock-Taussig shunt (BTS) was fully constructed before cannulation for cardiopulmonary bypass. The aortic cannula was inserted in the patent ductus arteriosus to allow systemic cold perfusion. When deep hypothermia was reached, the aortic cannula was redirected into the pulmonary artery (PA) confluence. Both cerebral and systemic perfusion were maintained through the right PA and BTS into the innominate artery.     

A reconsideration of cerebral perfusion in aortic arch replacement

Ten patients underwent aortic arch replacement for aneurysmal disease from 1970 to 1985 using a simplified cardiopulmonary bypass (CPB) technique with partial brachiocephalic perfusion, low CPB flow (30 to 50 ml/kg/min), moderate systemic cooling (26 degrees to 28 degrees C), and topical hypothermic myocardial protection. The arterial line from a single pump head has a Y shape to perfuse the femoral artery (20F cannula) and either the innominate or left carotid artery (14F). Of the 10 patients (mean age, 58 years) with arch aneurysm (6 atherosclerotic, 2 dissections, and 2 degenerative), 3 had previously undergone major cardiovascular operations. Concomitant procedures included aortic valve replacement in 4 and coronary artery bypass grafting in 3. Eight patients survived the procedure, and 1 died three weeks after operation of a ruptured abdominal aneurysm. Among the survivors, CPB time was 119 +/- 36 minutes (+/- standard deviation), myocardial ischemia time was 79 +/- 32 minutes, and intraoperative blood requirement was 5.9 +/- 3.4 units. There were no postoperative strokes. Neurological complications were only minor and included an asymptomatic miosis and ulnar nerve paresthesias in 1 patient and transient vocal cord palsy in another. Applicable in most patients undergoing elective resection of degenerative and atherosclerotic arch aneurysms and in selected patients with arch dissections, this simplified technique of brachiocephalic perfusion without circulatory arrest provides an attractive and safe alternative; the potential advantages are technical simplicity, reduced CPB and operating times, and satisfactory cerebral protection.     

Experience with the Norwood procedure without circulatory arrest.

OBJECTIVE: We evaluated a new cardiopulmonary bypass technique that allowed complete avoidance of circulatory arrest and deep hypothermia in the Norwood procedure for hypoplastic left heart syndrome. METHODS: A total of 10 patients were included in this study. The arterial line of the cardiopulmonary bypass circuit was divided in two in a Y shape; one branch was used for cerebral perfusion through the innominate artery and the other for lower body perfusion through the cannula inserted into the descending thoracic aorta. Moderate hypothermia (29 degrees C-31 degrees C rectal temperature) and high pump flow (150-180 mL. kg(-1). min(-1)) were used. A valveless conduit between the right ventricle and the pulmonary artery was used in 6 patients as an alternative pulmonary blood source to a conventional Blalock-Taussig shunt (n = 4). RESULTS: Circulatory arrest was completely avoided throughout the operation in all cases, and no complications from the new cardiopulmonary bypass technique were seen. Early deaths occurred in 3 cases. Neurologic deficits were not seen among the survivors, and the postoperative course was stable and uneventful, including satisfactory renal function. CONCLUSIONS: The Norwood procedure for hypoplastic left heart syndrome was successfully accomplished with complete avoidance of circulatory arrest by means of cerebral perfusion through the innominate artery combined with cannulation of the descending aorta. A conduit between the right ventricle and the pulmonary artery seems an excellent alternative pulmonary blood source, although right ventricular function needs to be carefully monitored.     

Hypothermic circulatory arrest through a left thoracotomy in a 12-year-old child with aortic coarctation

Surgical correction of adult complex aortic coarctation using hypothermic circulatory arrest often requires central cannulation to secure cerebral perfusion. It is not easy to place the cannula in the ascending aorta, however, especially in children undergoing surgery through a left thoracotomy. In a 12-year-old male with hypoplastic distal aortic arch, we placed an arterial cannula in the ascending aorta using the Seldinger puncture technique through the stenotic segment of the distal aortic arch. Replacement of the stenotic segment with a 20 mm-size Dacron graft was then routine. The ascending aorta was exposed only for the proximal anastomosis. The left subclavian artery was also reconstructed. This central cannulation technique is simple and is useful in repairing complex aortic coarctation.     

Hydrodynamics of aortic arch vessels during perfusion through the right subclavian artery

BACKGROUND: Performing subclavian artery cannulation in patients with an atherosclerotic ascending aorta or acute aortic dissection is of growing interest. To increase knowledge about pressure and flow distribution in the arch vessels, we investigated the in vitro perfusion characteristics in right subclavian artery cannulation. METHODS: Pressures and flow rates in the arch vessels of an aortic arch model were measured during perfusion through the right subclavian artery with different geometries and varying flow rates. Flow visualization was performed by laser light. RESULTS: In normal subclavian artery geometries, pressure and flow showed a significant increase in only the right common carotid artery (8 mm Hg and 25.5 mL/min, respectively, at 5.5 L/min pump flow). In cases of 50% stenosis at the right subclavian artery origin, a reduction of pressure and flow (6 mm Hg and 22.5 mL/min, respectively, at 5.5 L/min pump flow) in the right carotid artery caused by a suction effect was observed. CONCLUSIONS: Right subclavian artery cannulation provides a valuable alternative for ascending aortic cannulation, enabling nearly balanced arch vessel perfusion. Stenosis at the right subclavian artery origin carries the potential risk of slightly reduced perfusion of the right common carotid artery with questionable clinical relevance.     

Limiting circulatory arrest using regional low flow perfusion

Deep hypothermic circulatory arrest (DHCA) is commonly used for neonatal cardiac surgery. However, prolonged exposure to DHCA is associated with neurologic morbidity. The Norwood operation and aortic arch advancement are procedures that typically require DHCA during surgical correction. Regional low flow perfusion (RLFP) can be used to limit or exclude the use of circulatory arrest. This technique involves cannulation of the innominate or subclavian artery using a Gore-Tex graft, allowing isolated cerebral perfusion. Data was collected in 34 patients undergoing either neonatal aortic arch reconstruction or the Norwood procedure using RLFP. All patients had two arterial pressure monitors using either the umbilical or femoral artery catheters and radial or brachial catheters. Adequacy of perfusion was determined using cerebral saturation, blood flow velocity, mean arterial pressures, and arterial blood gas results. Cerebral saturation and blood flow velocity were monitored using the near-infrared spectroscopy (NIRS) (INVOS 5100, Somanetics Corp, Troy, MI) and a transcranial Doppler pulse-wave ultrasound (TCD) (EME Companion, Nicolet Biomedical, Madison, WI), respectively throughout the entire bypass period. Blood gases were monitored using a point of care blood gas analyzer (Gem Premier, Mallinckrodt Sensor System, Inc., Ann Arbor, MI). Data collected revealed total bypass times for repair between 69-348 min, with a mean of 180 min. Regional low flow perfusion times lasted between 6-158 min, with an average of 50 min., and DHCA times ranged from 0-66 min, with a mean of 19 min. The perfusion techniques used allowed patient clinical data to remain consistent throughout the cardiopulmonary bypass period, regardless of lower flows (Figure 1) The 30-day postoperative mortality rate was 2.9 %, with no evidence of neurologic injury during follow up. In conclusion, regional low flow cerebral perfusion might benefit patients by limiting the use of circulatory arrest during cardiac surgery. Further study is necessary to evaluate patient outcomes, comparing regional cerebral perfusion and circulatory arrest techniques.