Comparison of the Outcomes of Total Endovascular Aortic Arch Repair Between Branched Endograft and Chimney Endograft Technique in Zone 0 Landing.

PURPOSE: Zone 0 landing in thoracic endovascular aortic repair (TEVAR) has recently gained increasing attention for the treatment of high-risk patients. The aim of this study was to compare the outcomes of total endovascular aortic arch repair between branched TEVAR (bTEVAR) and chimney TEVAR (cTEVAR) in the landing zone (LZ) 0. MATERIALS AND METHODS: This was a single-center, retrospective, and observational cohort study. From January 2010 to March 2020, 40 patients (bTEVAR, n=25; cTEVAR, n=15; median age: 79 years) were enrolled in this study, with a median follow-up period of 4.1 years. These patients were considered unsuitable for open surgical treatment. RESULTS: All procedures were successful and no cases of conversion to open repair were noted during the 30-day postoperative period. The 30-day mortality was 2.5% (n=1; bTEVAR [0 of 25, 0%] vs cTEVAR [1 of 15, 6.7%]; p=0.375), the perioperative stroke rate was 10.0% (n=4; bTEVAR [4 of 25, 16.0%] vs cTEVAR [0 of 15, 0%], p=0.278), and type 1a endoleak rate was 15.0% (n=6; bTEVAR [0 of 25, 0%] vs cTEVAR [6 of 15, 40.0%], p=0.001). The risk factor for stroke was atheroma grade of ≥2 in the brachiocephalic artery (p<0.001). The risk factor for type 1a endoleak was cTEVAR (p=0.001). The 8-year survival rate was 49.9%. The aorta-related death-free rate and aortic event-free rate at 8 years were 94.4% (bTEVAR: 95.5% vs cTEVAR: 93.3%, p=0.504) and 60.7% (bTEVAR: 70.7% vs cTEVAR: 40.0%, p=0.048), respectively. CONCLUSIONS: Total endovascular aortic arch repair using bTEVAR and cTEVAR is feasible for the treatment of aortic arch diseases in high-risk patients who are unsuitable for open surgery. However, as the rate of stroke is high, strict preoperative evaluation to prevent stroke is needed. No rupture of the aneurysm was observed in cTEVAR, but patients should be selected carefully because of the high incidence of type 1a endoleak.

Effectiveness of Proximal Landing Zones 0, 1, and 2 Hybrid Thoracic Endovascular Aortic Repair: A Single Centre 12 Year Experience.

OBJECTIVE: Hybrid thoracic endovascular aortic repair (TEVAR) is being accepted increasingly as a first line treatment for arch repair at the present authors' institution. This study aimed to clarify the effectiveness of zones 0, 1, and 2 landing hybrid TEVAR. METHODS: This was a retrospective single centre case series. From April 2008 to March 2020, 348 patients (median age 72 years; interquartile range [IQR] 65, 77 years) were enrolled, with a median follow up period of 5.6 years (IQR 2.6, 8.7 years). The procedures included zone 0 in 135 patients (38.8%), zone 1 in 82 patients (23.6%), and zone 2 proximal landing zone (LZ) hybrid TEVAR in 131 patients (37.6%). The pathologies consisted of dissecting aortic aneurysms in 123 (35.3%) patients. Emergency procedures were performed in 39 (11.2%) patients. RESULTS: The 30 day mortality (n = 2, 0.6%) and hospital deaths (n = 6, 1.7%) were registered. The stroke rate was 1.1% (n = 4), while early and late endoleak rates were 4.8% (n = 17) and 1.7% (n = 6), respectively. Type 1a endoleak and retrograde type A dissection occurred in seven (2.0%) and three (0.9%) patients, respectively. The cumulative survival, freedom from aorta related deaths, and freedom from aortic events in 10 years were 75.0%, 97.2%, and 84.1%, respectively. The freedom from aortic events in each landing zone in 10 years was 82.3%, 81.4%, and 87.9% for zones 0, 1, and 2, respectively. The 10 year survival rates were 82.5% and 73.6%; the 10 year aorta related death free rates were 94.9% and 98.6%, and the 10 year aortic event free rates were 82.3% and 85.5% in the zone 0 and zone 1 and 2 TEVAR, respectively. CONCLUSION: Satisfactory early and long term results of hybrid arch repair at zones 0, 1, and 2 were achieved. To avoid complications and aortic events, the treatment strategy of hybrid arch repair for aortic arch pathologies should be tailored using accurate pre-operative assessment of the ascending aorta and the aortic arch.

Successful trans-femoral retrieval of a stuck axillary Impella 5.0 device.

We describe a case in which an axillary Impella 5.0, stuck in an area of calcification in the right subclavian artery, could not be retrieved in the usual manner. However, it was successfully removed using a long 22-Fr sheath and snaring catheter by means of the trans-femoral artery. Device retrieval using the trans-femoral artery snare technique is considered a valid option for removing the Impella device in patients who exhibit this complication.

Risk Analysis of Aneurysm Sac Enlargement Caused by Type II Endoleak after Endovascular Aortic Repair.

BACKGROUND: Although the preoperative risk factors associated with the occurrence of type II endoleak (ETII) after endovascular aortic repair (EVAR) have gradually become more evident, the preoperative risk factors associated with aneurysm sac enlargement caused by ETII remain unclear. This study aimed to determine the preoperative risk factors associated with aneurysm sac enlargement caused by ETII after EVAR. METHODS: This retrospective cohort study reviewed 519 EVARs performed for true abdominal aortic aneurysm between January 2006 and December 2018 at our institution. EVARs using commercially available bifurcated devices with no type I or III endoleaks during follow-up and with ≥12 months follow-up were included. A total of 320 patients were enrolled in the study. To identify the preoperative risk factors of sac enlargement after EVAR, Cox regression analysis was used to assess preoperative data. RESULTS: The median follow-up period was 60.8 months. Overall, 135 of 320 patients (42%) had ETII during follow-up, and 47 of 135 patients (35%) developed aneurysm sac enlargement. Multivariate analysis revealed that chronic kidney disease (CKD) stage ≥4 (hazard ratio [HR], 4.65; 95% confidence interval [CI], 2.13-10.15; P = 0.001), patent inferior mesenteric artery (IMA) (HR, 17.85; 95% CI, 2.46-129.73; P< 0.001), and number of patent lumbar arteries (LAs) (HR, 1.37; 95% CI, 1.13-1.68; P= 0.002) were risk factors of aneurysm sac enlargement caused by ETII. CONCLUSIONS: CKD stage ≥4, patent IMA, and number of patent LAs were independent risk factors for aneurysm sac enlargement after EVAR. In particular, patent IMA had the highest HR and seemed to have the greatest impact on long-term aneurysm sac enlargement. Hence, taking preoperative measures to address a patent IMA appears to be important in reducing the incidence of sac enlargement.

Successful Hybrid Zone 0 Landing Thoracic Endovascular Aortic Repair for Ascending Aortic Pseudoaneurysm after Bentall Procedure and Coronary Artery Bypass Grafting in Takayasu Arteritis.

Pseudoaneurysm at the suture line is one of the most common complications in aortic surgery for Takayasu arteritis (TA) and is associated with a high mortality rate. A 52-year-old man with TA, who previously underwent the Bentall procedure and 2 redo surgeries for coronary artery obstruction and a pseudoaneurysm of a coronary button, was diagnosed with an anastomotic pseudoaneurysm in the ascending aorta. Hybrid zone 0 debranching thoracic endovascular aortic repair was performed, and the patient was discharged uneventfully on postoperative day 8.

Overview of the 82nd Annual Scientific Meeting of the Japanese Circulation Society　- Futurability: Pioneering the Future of Circulatory Medicine.

The 82nd Annual Scientific Meeting of the Japanese Circulation Society was held in Osaka, Japan, on March 23-25, 2018, when the cherry blossoms were just opening everywhere around the venue. This was the 5th Annual Scientific Meeting of JCS in which a cardiovascular surgeon served as Congress Chairperson. The main theme of this meeting was "Futurability: Pioneering the Future of Circulatory Medicine". The word, futurability, is a neologism of future ability, because we now have to contemplate what constitutes the essence of cardiovascular medicine, how it should develop as medicine for future generations, and how its ability should be displayed. The meeting was favored by splendid weather and the number of participants was recorded as being higher than 18,700. There were heated and profound discussions about the "futurability" of cardiology, cardiovascular surgery, and heart team medical care as well, in every session. The meeting was successfully completed and we sincerely appreciate the great cooperation and support from all affiliates.

Severe tricuspid regurgitation after mitral valve surgery: the risk factors and results of the aggressive application of prophylactic tricuspid valve repair.

PURPOSE: This study aimed to examine the risk factors for severe postoperative tricuspid regurgitation (TR) in patients undergoing mitral valve surgery. We also studied the effects of prophylactic tricuspid valve repair (TVR) on severe postoperative TR. METHODS: We retrospectively studied 125 patients without severe TR who underwent mitral valve surgery from 1987 to 2006. Patients did not undergo TVR before 1998 (the early period, n = 54). In 1998 (the late period, n = 71), patients with a preoperative tricuspid annular diameter of ≥35 mm underwent TVR using an annuloplasty ring (n = 52). RESULTS: In the analysis of the early period, the rates of freedom from severe TR at 10 and 20 years after surgery were 76 and 59 %, respectively. A multivariate analysis identified moderate preoperative TR as a significant risk factor for severe TR. In the late period, none of the 52 patients who underwent TVR developed severe TR. However, 4/19 patients who did not undergo TVR developed severe TR, and all of these four patients had a preoperative tricuspid annular diameter of ≤35 mm. CONCLUSIONS: Moderate preoperative TR is a significant risk factor for severe postoperative TR in patients undergoing mitral valve surgery. The aggressive application of TVR can prevent severe postoperative TR; however, tricuspid annular dilatation might not be a good indicator for TVR.

[Surgical Technique for Massive Shunt after Repair of Post-infarction Ventricular Perforation].

We report a case of large anterior septal perforation (40×20 mm) immediately following repair of ventricular septal perforation( 9×9 mm) with the infarction exclusion technique. The large perforation was successfully repaired through a left ventriculotomy with a combined double patch/cone-shaped patch technique. This technique can be effective not only in cases of large laceration of ventricular septum as a consequence of inappropriate repair but also of large septal perforation with extensive fragility of the septal myocardium.

Clinical experience with the RELAY NBS PLUS stent-graft for aortic arch pathology.

PURPOSE: To assess the safety, efficacy and performance of the RELAY NBS PLUS stent-graft in patients with aortic arch pathology. METHODS: From July 2010 to December 2011, the RELAY NBS PLUS was used to treat 13 patients (eight males; mean age 59.8 years, range 29-78 years) suffering from aortic arch pathology. The distribution of the proximal landing zone was Zone 0 in one case, Zone 1 in three cases and Zone 2 in nine cases. Bypass of the cervical branches was performed in 11 patients. RESULTS: The surgery-related mortality within 30 days and postoperative morbidity were 0%. Postoperative computed tomography at discharge confirmed 100% clinical success without any endoleaks. The mean radius of the inner curve in the aortic arch was 16.2 mm (range 5.8-25.7 mm). We detected two bird-beak configurations with a severely angulated aortic arch with a radius of the inner curve <15 mm. At the mid-term follow-up (mean 22.1 months; range 13.8-28.2 months), all patients were alive without aorta- or device-related complications. CONCLUSIONS: RELAY NBS PLUS stent-grafts can be safely and effectively implanted with controlled deployment to satisfactorily repair aortic arch pathology, even in the cases considered to present with an unfavorable anatomy for the first generation commercially available stent-graft devices. These encouraging outcomes will need to be confirmed in a larger series with a longer follow-up.

Scallop technique of urgent endovascular repair for symptomatic throacoabdominal aortic aneurysm with a ready-made device.

A 72-year-old woman had a large thoracoabdominal aortic aneurysm (TAAA) with abdominal pain. This aneurysm involved the celiac artery and the superior mesenteric artery (SMA). The risk of open surgery was very high due to severe comorbidity, and there was no appropriate distal attachment for thoracic endovascular repair (TEVAR) with ready-made devices. Therefore, TEVAR with the scallop technique was performed in this urgent setting. A scallop was created in a Talent thoracic stent graft. The aneurysm was successfully excluded, and perfusion in the SMA was preserved using this scalloped endograft. The scallop technique with a ready-made device may be one of the treatment options for urgent TAAA.

Salvage surgery for stage IVa thymic carcinoma combined with aortic arch resection - case report.

BACKGROUND: Although complete surgical resection of thymic carcinoma is a prognostic factor, extended surgery combined with a major blood vessel procedure remains controversial because of the increased risk of mortality. We report a case of Stage IVa thymic carcinoma successfully resected with a pneumonectomy along with aortic arch replacement after chemotherapy. CASE PRESENTATION: A 45-year-old male was diagnosed with thymic carcinoma invasion to the aortic arch and left pulmonary artery. Malignant pericardial effusion was also noted, though disappeared after chemotherapy, thus surgical options were considered. A radical resection procedure including left pneumonectomy, aortic arch replacement with total rerouting of the supra-arch vessels, and right pulmonary artery plication was performed. The postoperative course was uneventful and the patient has been disease-free for 3 years. CONCLUSION: Extended salvage surgery might be a valuable option for advanced thymic carcinoma.

Extrathoracic collaterals to critical segmental arteries after endovascular thoraco-abdominal aneurysm repair.

OBJECTIVES: The risk of spinal cord injury after thoraco-abdominal aortic aneurysm repair increases when the segmental arteries (SAs) in the critical segment are sacrificed. Such critical SAs cannot be reconstructed when performing thoracic endovascular aortic repair (TEVAR). We aimed to elucidate extrathoracic collaterals to the critical SAs (T9-L1) that develop after TEVAR. METHODS: Between 2006 and 2018, the critical SAs (T9-L1) of 38 patients were sacrificed during TEVAR. Nineteen of these patients who underwent multidetector row computed tomography 6 months after surgery were included (mean age 60 ± 13 years; 10 male; Crawford extent II:III, 14:5). We retrospectively assessed extrathoracic collaterals to the sacrificed critical SAs. RESULTS: Ninety-four collaterals to the critical SAs were observed, originating from the subclavian (26/94), external iliac (50/94) and internal iliac (18/94) arteries. Twenty-five of the 26 (96%) collaterals from the subclavian artery were from its lateral descending branch, and 19 of the 26 (73%) collaterals fed into T9. Forty-three of the 50 (86%) collaterals from the external iliac artery were from its lateral ascending branch, and 25 of the 50 (50%) collaterals communicated with T11. Patients with a history of left thoracotomy (no collaterals in 6 patients) had fewer collaterals via the lateral descending branch of the left subclavian artery in comparison with the patients without (10 collaterals in 13 patients) (P = 0.009). CONCLUSIONS: After critical SAs were sacrificed, extrathoracic collaterals developed with certain regularity. Previous left thoracotomy could influence the development of extrathoracic collaterals from the left subclavian artery.

An evaluation of the long-term patency of the aortocoronary bypass graft anastomosed to a vascular prosthesis.

OBJECTIVES: Although concomitant surgery for coronary artery disease (CAD) and thoracic aortic aneurysm is performed often, the long-term patency of the coronary artery bypass grafting (CABG) anastomosed to a vascular prosthesis has not been fully investigated. Here, we explored the long-term patency of the graft in comparison with the proximal anastomosis site on the native ascending aorta or vascular prosthesis. METHODS: A total of 84 patients with concomitant CABG who underwent surgery for thoracic aortic aneurysm at 3 Osaka Cardiovascular Research Group institutes were retrospectively investigated for this study. The patency of 109 aortocoronary bypasses using saphenous vein grafts was evaluated with computed tomography angiography or coronary angiography, comparing the grafts anastomosed on the vascular prosthesis (group P, n = 75) to those anastomosed on the native ascending aorta (group N, n = 34). RESULTS: During 45.9 ± 39.7 months follow-up, significantly worse patency of the grafts in group P was revealed when compared with those in group N (100% vs 77.6% in 12 months, 100% vs 52.7% in 36 months and 100% vs 31.6% in 57 months, log rank P < 0.001). The poor patency of the grafts was confirmed in each target lesions (left anterior descending artery: P = 0.050, right coronary artery: P = 0.045, left circumflex artery: P = 0.051) and regardless of the severities of the target coronary vessels (severe stenosis: P = 0.013, mild-to-moderate stenosis: P = 0.029). Furthermore, an analysis of graft occlusion risk factors using the univariate Cox proportional hazards model revealed that the proximal anastomosis site on the vascular prosthesis was the sole risk factor for graft occlusion (P < 0.001). CONCLUSIONS: In the simultaneous surgery for CAD and thoracic aortic aneurysm, CABG design from vascular prosthesis to coronary artery should be avoided if possible, although further studies are warranted.

Successful surgery localized to the infected lesion as diagnosed by 18F-fluorodeoxyglucose positron emission tomography/computed tomography for extended-aortic prosthetic graft infection.

INTRODUCTION: We describe the successful treatment of a patient with extended-aortic prosthetic graft infection (PGI) by surgery limited to the infected lesion based on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) findings. PRESENTATION OF CASE: A 54-year-old man, who had undergone three graft replacements (GRs) for extended-thoracic aortic aneurysms, was diagnosed with PGI complicated by an aorto-esophageal fistula. On the basis of 18F-FDG PET/CT findings, we performed a redo total arch replacement, preserving the other prosthesis where abnormal FDG uptake was not detected. All the resected tissues were positive for gram positive coccus. There were no signs of infection recurrence at 2 years postoperatively. DISCUSSION: Since activated inflammatory cells such as macrophages uptake FDG, FDG-PET/CT clarifies the localization of the infected prosthesis precisely. CONCLUSION: Surgery localized to the infected sites detected by FDG-PET/CT can be an effective option for PGI in cases with previous multiple GRs.

Effectiveness of embolic protection filter devices in stroke prevention during endovascular aortic arch repair in significant aortic atheroma patients.

OBJECTIVES: The objective of this study was to evaluate the effectiveness of embolic protection filter device in stroke prevention during hybrid endovascular arch repair in patients with significant aortic atheroma. METHODS: Twenty-two patients (20 men, mean age 79.0 years, mean logistic EuroSCORE 23.9%) with aortic arch/proximal descending aortic diseases and significant aortic atheroma (atheroma grade ≥ II) who were deemed unfit for conventional open surgery underwent endovascular aortic arch repair with protection of the supra-arch vessels using a balloon catheter and filter devices. The effectiveness in preventing stroke was evaluated by a postoperative neurological examination protocol, which was followed by neuroimaging with computed tomography/DW-magnetic resonance imaging (MRI) study in cases with neurological deficits. RESULTS: The atheroma grades of the aortic arch were II, III and IV in 36%, 14% and 50% of the patients, respectively. In total, 37 filter devices were placed in the supra-aortic vessels (5 brachiocephalic arteries, 23 carotid arteries, 5 subclavian arteries and 4 vertebral arteries). Technical success was achieved in all patients, and 30-day mortality was 4.5% (1/22 cases). Two (9.1%) cases showed neurological symptomatic stroke postoperatively. With DW-MRI examination, a major new region was detected in the filter-protected left carotid artery in one case and in the balloon-protected left vertebral artery in another case. CONCLUSIONS: In high-risk patients with significant aortic arch atheroma, hybrid endovascular aortic arch repair with embolic protection using a filter device showed satisfactory early results. Filter protection could be an attractive adjunct manoeuvre for preventing critical stroke during endovascular arch repair.

Combined Aortic Arch Resection for Lung Cancer Using Total Rerouting of Supra-Arch Vessels.

Surgery for aortic arch involvement in lung cancer cases is challenging, and generally requires extracorporeal circulation with circulatory arrest or a cerebral protection technique. To reduce morbidity, we developed a novel surgical technique for total aortic arch replacement for lung cancer with aortic arch involvement that features total rerouting of supra-arch vessels under a beating heart condition. A 56-year-old man was diagnosed with lung cancer, and aortic arch invasion was suspected. After concurrent chemoradiotherapy, a left upper lobectomy with total arch replacement was performed using our new technique. Thirty-six months after the operation, there was no recurrence.

Silent cerebral infarction after thoracic endovascular aortic repair: a magnetic resonance imaging study.

OBJECTIVES: Silent cerebral infarction is the most common brain injury incidentally detected on imaging and can be associated with increased risks of future stroke and cognitive decline. However, the incidence and risk factors of silent cerebral infarction after thoracic endovascular aortic repair (TEVAR) for aortic arch pathologies remain unclear. This study aimed to examine silent cerebral infarction following TEVAR using diffusion-weighted (DW) magnetic resonance imaging (MRI). METHODS: Nineteen patients (16 men, mean age 73.3 years) who underwent elective debranching TEVAR (zone 0/1/2 = 3/8/8) were included. Perioperative brain injury was assessed via cerebral DW-MRI before and after the procedure. The atheroma ratio was calculated from preoperative computed tomography images, and we examined the association between the atheroma ratio and development of new postoperative DW-MRI lesions. RESULTS: Technical success was achieved in all patients, and no patient died within 30 days postoperatively. Postoperative DW-MRI detected a total of 24 new lesions in 5 (26%) patients (1-9 lesions per patient): 4 (21%) patients with silent cerebral infarction and 1 (5%) patient with clinical stroke. The atheroma ratio of the aortic arch (23.8 ± 2.7% vs 18.3 ± 3.9%; P = 0.023), especially at the proximal landing zone (19.5 ± 2.8% vs 14.7 ± 2.7%; P = 0.014), was significantly higher in patients with new postoperative DW-MRI lesions than that in patients without. CONCLUSIONS: The incidence of silent cerebral infarction following TEVAR with supra-aortic debranching for aortic arch pathologies was 21%, and the severity of atheromatous change in the aortic arch, especially in the proximal landing zone, was positively associated with the development of silent cerebral infarction.

Complete resection of local advanced thymic carcinoma with total aortic arch replacement after chemotherapy: a case report.

BACKGROUND: Although complete surgical resection of thymic carcinoma is a prognostic factor, it is not always an option for advanced tumors because of locoregional invasion. Extended surgery combined with a major blood vessel procedure remains controversial because of the increased risk of mortality. CASE PRESENTATION: Chest computed tomography (CT) uncovered an abnormal shadow in the mediastinum of a 74-year-old man. An irregularly shaped tumor obstructed the left innominate vein, and invasion of the aortic arch was suspected. A CT-guided percutaneous needle biopsy revealed squamous cell carcinoma of the thymus, which was considered unresectable. The patient underwent chemotherapy elsewhere, then was referred to us for surgical resection. We combined extended surgery with total aortic arch replacement under a cardiopulmonary bypass. Complete resection was achieved, and the patient remains alive without recurrence at 3 years after surgery CONCLUSION: Resection including aortic arch replacement might be an option that can achieve complete resection of local advanced thymic carcinoma.

Quantitative evaluation of blood flow in each cerebral branch associated with zone 1-2 thoracic endovascular aortic repair.

OBJECTIVES: Optimal methods to quantitatively evaluate the blood flow in each cerebral artery after zone 1-2 thoracic endovascular aortic repair (TEVAR) remain unknown. Our objective was to evaluate the differences between preoperative and postoperative cerebral artery blood flows after zone 1-2 debranching TEVAR (dTEVAR). METHODS: Between January 2016 and August 2018, a prospective analysis of the blood flow in both the internal carotid artery and the vertebral artery in 16 patients before and after zone 1-2 dTEVAR was conducted. Zone 1 dTEVAR with right axillary artery-left common carotid artery-left axillary artery (RAxA-LCCA-LAxA) bypass was performed on 7 patients. Zone 2 dTEVAR was performed on 9 patients: 4 underwent RAxA-LAxA bypass and 5 underwent LCCA-LAxA bypass. Quantitative magnetic resonance angiography was performed before and after zone 1-2 dTEVAR. RESULTS: Total intracranial blood flow was preserved postoperatively [The median (interquartile range) preoperatively vs postoperatively: 621 (549-686) vs 638 (539-703) ml/min, not significant]. The anterior [469 (400-504) vs 475 (404-510) ml/min, not significant] and posterior cerebral blood flows [157 (121-199) vs 163 (123-210) ml/min, not significant] were also maintained postoperatively. In the 3 debranching procedures, the postoperative anterior and posterior cerebral blood flows were maintained at rates similar to preoperative rates, with the proportion of anterior and posterior cerebral circulations reaching almost 75% and 25%, respectively. No significant differences between preoperative and postoperative distributions of internal carotid artery blood flows were observed. Regarding vertebral artery blood flows, the distribution of blood flow through the left vertebral artery was significantly lower postoperatively than preoperatively; however, the postoperative right vertebral artery blood flow distribution significantly increased compared with the preoperative flow. CONCLUSIONS: In zone 1-2 dTEVAR, total intracranial blood flow was preserved postoperatively, and the postoperative anterior and posterior cerebral circulations were maintained at rates similar to their preoperative rates.