Cerebral regional oxygenation during aortic coarctation repair in pediatric population.

OBJECTIVE: During repair of aortic coarctation, clamping of the transverse aortic arch proximal to the left common carotid artery occludes blood flow to the left carotid and vertebral arteries. The objective of the present study is to determine whether blood flow through the right carotid and vertebral arteries provides adequate cerebral blood flow during aortic cross-clamping, as assessed by near-infrared spectroscopy. METHODS: In 11 consecutive children undergoing aortic coarctation repair through a standard posterolateral thoracotomy, regional cerebral oxygen saturation (cSO(2)) was measured using near-infrared spectroscopy. Six patients underwent an extended end-to-end repair, in which the aortic cross-clamp was placed in between the innominate and left common carotid arteries (extended repair group). Five patients underwent a standard end-to-end repair in which the cross-clamp was clamp placed between the left common carotid and subclavian arteries (standard repair group). RESULTS: After aortic clamping, there was a significant decrease in cSO(2) in the extended repair group, whereas the cSO(2) increased in the standard repair group (-9.2+/-12.2 vs 6.0+/-5.1%, extended vs standard repair groups, p=0.03). In the extended repair group, the cSO(2) decreased linearly during the aortic cross-clamping period (r(S)=-0.842, p<0.001), while in the standard repair group, the cSO(2) increased during the same time period (r(S)=0.786, p<0.001). Regression analysis identified the site of aortic cross-clamping as the sole independently significant variable explaining changes in the cSO(2) during aortic cross-clamping (p<0.03), whereas neither age nor duration of aortic cross-clamping was statistically significant. There were no postoperative neurological impairments in either group of patients. CONCLUSION: During aortic coarctation repair, aortic cross-clamping proximal, as compared to distal, to the left carotid artery is associated with significantly decreased regional cerebral oxygen saturation, as measured by near-infrared spectroscopy. Although no short-term clinical impairments were identified, long-term follow-up in a larger cohort is needed to study the effects of unbalanced cerebral oxygenation during clamping of the transverse arch. These data suggest that cerebral saturation monitoring is warranted, and may be indicative of cerebral hypoperfusion.     

Distal Aortic Arch Replacement for Aneurysmal Disease: The Value of Preparatory Carotid Subclavian Reconstruction

Between November 2000 and January 2002, two patients with aneurysms that involved the distal part of the aortic arch including the left subclavian artery were treated at our institution. Patient 1 had an aneurysm of 5.8 cm extending to the proximal descending aorta. Patient 2 had a 6.8 cm type II thoracoabdominal aneurysm extending proximal to the aortic bifurcation. Both patients had left subclavian-to-carotid transposition in preparation for distal aortic arch replacement. Complete replacement of the descending thoracic and abdominal aorta was carried out in patient 2. Both cases were done with distal aortic perfusion, spinal catheter drainage, and dual lumen endotracheal anesthesia. There was no mortality. There were no cerebrovascular complications in spite of the fact that patient 1 required aortic cross-clamping between the innominate and left carotid artery. There was no paraplegia, renal failure, or mesenteric or lower extremity complications. Patient 1 had postoperative vocal cord palsy, eventually requiring medialization procedure. He recovered normal voice. Both patients remain alive and well at the time of last follow-up (7 to 20 months). Carotid subclavian reconstruction in preparation for distal aortic arch replacement facilitates the performance of the proximal anastomosis and attempts to maintain flow through the left vertebral system during aortic cross-clamping. This may reduce the risk of stroke during distal aortic arch replacement.     

Complications associated with clamping the aorta between the left common carotid artery and left subclavian artery

BACKGROUND: Hypothermic circulatory arrest using a left thoracotomy has recently been recommended for repair of distal arch lesions to prevent the atheroembolism that often results from clamp injury. The recommendation holds even for cases in which aortic cross-clamping between the left common carotid artery and left subclavian artery is possible. METHODS: Over the last 16 years, 69 patients underwent repair of the distal arch or descending thoracic aorta using distal perfusion with the proximal aortic clamp placed between the left common carotid and left subclavian artery. The average age of the patients was 61+/-12 years; 18 of them (26%) were older than 70 years. Forty-four patients (64%) had atherosclerotic true aneurysms. RESULTS: The surgical procedures used included patch closure of saccular aneurysms in 20 patients (29%) and graft replacement in 47 (71%). The left subclavian artery was reattached in 7 patients (10%). Although there were 3 hospital deaths (4%), no cerebral complications occurred aside from temporary neurologic dysfunction in 4 patients (6%). CONCLUSIONS: An acceptably low incidence of cerebral complications is associated with cross-clamping the aorta between the left common carotid artery and left subclavian artery.     

Aneurysms of the descending thoracic aorta: Three hundred sixty-six consecutive cases resected without paraplegia

Purpose: The aim of this study was to present a 20-year experience with a single method of passive distal perfusion during descending thoracic aortic aneurysm resection.Method: Aortic repair with a Dacron graft interposition was performed for 366 consecutive aneurysms located between the left subclavian artery and the crux of the diaphragm. The extent of aorta resected in 335 patients (91.5%) represented one third or less of the aortic length. A 9 mm Gott shunt was cannulated proximally into the ascending aorta (235 cases), the aortic arch (60 cases), the descending aorta (68 cases), or the left ventricle (3 cases) and inserted distally into the descending aorta (232 cases), the femoral artery (127 cases), or the abdominal aorta (7 cases). Shunt flows were recorded in 91 cases and varied from 1100 ml to 4900 ml/min, (mean 2526 ml/min). Distal pressure during shunting was measured in 62 patients. It varied from 15 to 120 mm Hg (mean 64.5 mm Hg). The aortic cross-clamp time varied from 8 to 124 minutes (mean 30 minutes).Results: The hospital death rate was 12% overall and 9.9% (35/351) if ruptured aneurysms are excluded. Among 359 operating room survivors, neither immediate nor delayed ischemic spinal cord deficit occurred. Transient renal dysfunction occurred in nine patients (2.4%) and kidney failure in one (0.2%). Five deaths (1.3%) were shunt related.Conclusion: Distal perfusion with the 9 mm Gott shunt has proven to be an effective method to preserve spinal cord function. The limited extent of aorta resected and the brief aortic cross-clamp time may also be interactive factors of protection. (J VASC SURG 1995;21:385-91.)     

Paraplegia after thoracic aortic occlusion: influence of cerebrospinal fluid drainage. Experimental and early clinical results

Paraplegia occurs in 6.5% to 40% of patients after repair of extensive thoracoabdominal aortic aneurysms requiring aortic clamping. This study aimed to determine whether drainage of cerebrospinal fluid (CSF) done before aortic cross-clamping could decrease the incidence of paraplegia in dogs. The descending thoracic aorta was clamped distal to the left subclavian artery for either 40 minutes (group I) or 60 minutes (group II). All control animals in group I (10) and group II (10) showed evidence of spinal cord injury with paraparesis or paraplegia. In contrast, 9 of 10 animals (90%) in group I and 7 of 10 animals (70%) in group II that had CSF drainage before aortic cross-clamping were neurologically normal (p less than 0.001 and p less than 0.01, respectively). Aortic pressure distal to the aortic cross clamp was the same in all groups; however, spinal cord perfusion pressure (distal aortic pressure minus CSF pressure) was significantly higher in neurologically normal animals (34 +/- 5 mm Hg, n = 15) compared with those with paraparesis (26 +/- 4 mm Hg, n = 8) or paraplegia (19 +/- 5 mm Hg, n = 8) (r = 0.871, p less than 0.001). This study demonstrates that drainage of CSF before thoracic aortic occlusion significantly increases spinal cord perfusion pressure and decreases the incidence of paraplegia. Limited early clinical experience suggests that CSF drainage may be a useful adjunct to prevent paraplegia in patients who are having repair of thoracoabdominal aortic aneurysms.     

Is paraplegia after repair of coarctation of the aorta due principally to distal hypotension during aortic cross-clamping?

The hypothesis is presented that paraplegia after coarctation of the aorta is principally due to hypotension of sufficient severity and duration. In a group of 103 patients who underwent surgery during a 10-year period, the distal aortic pressure was maintained above 60 mm Hg while the aorta was cross-clamped or the period of cross-clamping was limited to less than 20 minutes. No neurologic problems occurred. In 17 of the 103 cases aortic pressure decreased below 60 mm Hg, occurring in 8% of patients with the aorta occluded below the left subclavian artery but in 30% of those occluded above. Therapeutic measures used in the 17 patients included infusion of metaraminol in five and limiting cross-clamp time to less than 20 minutes in 11. The theory is proposed that ligation of intercostal arteries in a patient with coarctation cannot injure the spinal cord because the normal direction of blood flow is reversed. Certainly, in patients without a coarctation, such as thoracic aneurysms, ligation of a critical intercostal artery may injure the spinal cord. However, in patients with coarctation the direction of blood flow is reversed, blood flowing from the intercostals into the distal aorta. The vague relationship long noted between development of collateral circulation, including rib notching, and the frequency of paraplegia probably depends not on the presence of enlarged intercostal arteries but on whether their temporary occlusion at the time of aortic cross-clamping results in distal hypotension. Data with somatosensory-evoked potentials measured during operations on the thoracic aorta in 25 patients found no changes in sensory potentials as long as the distal aortic pressure remained above 60 mm Hg, but a gradual disappearance was found at lower pressures. In five of six patients with large thoracicoabdominal aneurysms in whom sensory potentials were absent for longer than 30 minutes, paraplegia resulted. Use of somatosensory potentials provides a significant method for evaluating methods to protect from paraplegia. This method should be far more productive than are simple clinical experiences because the fortunate rare occurrence of paraplegia, one in 200, greatly limits available data.     

Neonatal aortic arch reconstruction avoiding circulatory arrest and direct arch vessel cannulation.

BACKGROUND: Aortic arch reconstruction in neonates routinely requires deep hypothermic circulatory arrest. We reviewed our experience with techniques of continuous low-flow cerebral perfusion (LFCP) avoiding direct arch vessel cannulation. METHODS: Eighteen patients, with a median age of 11 days (range 1 to 85 days) and a mean weight of 3.2 +/- 0.8 kg, underwent aortic arch reconstruction with LFCP. Seven had biventricular repairs with arch reconstruction, 9 underwent the Norwood operation and 2 had isolated arch repairs. In 1 Norwood and 7 biventricular repair patients, LFCP was maintained by advancing the cannula from the distal ascending aorta into the innominate artery. In 8 of 9 Norwood patients, LFCP was maintained by directing the arterial cannula into the pulmonary artery confluence and perfusing the innominate artery through the right modified Blalock-Taussig shunt fully constructed before cannulation for cardiopulmonary bypass. In 2 patients requiring isolated arch reconstruction, the ascending aorta was cannulated and the cross-clamp was applied just distal to the innominate artery. RESULTS: LFCP was maintained at 0.6 +/- 0.2 L x min(-1) x m(-2) for 41.0 +/- 13.9 minutes at 18.5 degrees C +/- 1.1 degrees C. In 10 of the 18 patients, blood pressure during LFCP was 15 +/- 8 mm Hg remote from the innominate artery (left radial, umbilical or femoral arteries). In 8 of the 18 patients, right radial pressure during LFCP was 24 +/- 10 mm Hg. The mean mixed-venous saturation was 79.8% +/- 10% during LFCP. Two patients had preoperative seizures, whereas none had seizures postoperatively. One patient died. CONCLUSIONS: Neonatal aortic arch reconstruction is possible without circulatory arrest or direct arch vessel cannulation. These techniques maintained adequate mixed-venous oxygen saturations with no associated adverse neurologic outcomes.     

Surgery of the descending thoracic aorta: spinal cord protection with the Gott shunt

From July, 1974, to July, 1987, surgical treatment of descending thoracic aortic aneurysms was performed in 173 patients at l'H?pital du Sacré-Coeur de Montréal. The cause of the aneurysms was arteriosclerosis or medial degeneration in 83 patients, trauma in 50, dissection in 34, and a congenital malformation in 6. A single method of external shunting provided distal perfusion in all patients in the series. A 9-mm Gott aneurysm shunt was placed preferentially between the ascending aorta (67%) and the descending aorta (60%). Alternative sites of proximal cannulation (aortic arch, 9%; proximal descending aorta, 22%; left ventricle, 2%) and distal cannulation (abdominal aorta, 3%; left femoral artery, 37%) were chosen based on the location and the extent of the aortic aneurysm. No systemic heparinization was used. In the last 40 patients, a flowmeter adapted for use with the shunt allowed the recording of shunt flow (mean, 2,475 ml/min; range, 1,100 to 4,000 ml/min). Hospital mortality, including patients with ruptured aneurysms, was 15% (26/173). The mean aortic cross-clamp time was 37 minutes (range, 8 to 105 minutes). Of the 173 patients, 168 survived long enough to allow accurate clinical evaluation of the function of the spinal cord: no paraplegia or other spinal cord ischemic injury occurred. To date, our clinical experience has demonstrated the effectiveness of the 9-mm Gott shunt in preserving the functional integrity of the spinal cord during cross-clamping of the thoracic aorta.     

Circulatory support during crossclamping of the descending thoracic aorta. Evidence of improved organ perfusion

The need to support the distal circulation during aortic crossclamping and the subsequent effects on hemodynamics and organ perfusion prompted our review of 51 patients who underwent repair of aneurysm of the descending thoracic aorta from 1983 through 1987. Forty-three patients had aneurysms originating distal to the left subclavian artery, and eight had aneurysms involving the distal aortic arch and the proximal descending aorta; 10 patients had emergency operation for aneurysm rupture. Three different techniques were used: Seventeen patients had left atrial-distal aorta arterial bypass with a centrifugal pump, 18 patients had a Gott shunt, and 16 patients had no circulatory support during aneurysm repair. Location and type of aneurysm, age, sex, diabetes, preoperative hypertension, and serum lipid levels were similar in the three groups. Duration of crossclamping was 54 +/- 12 minutes for left atrial-aortic assist, 45 +/- 5 for the shunt group, and 34 +/- 4 for patients without circulatory support. With crossclamping, all groups had similar and significant increases in heart rate (p less than 0.03). Proximal systolic blood pressure did not change during left atrial-aortic assist, but a transient increase occurred in patients with shunts (p less than 0.01), and a sustained increase occurred in patients without circulatory support (p less than 0.05). With crossclamp release, arterial pH and capillary pulmonary wedge pressure decreased significantly (p less than 0.05) in patients without shunt or bypass. Postoperative renal function did not vary significantly when circulatory support was used, but serum creatinine rose transiently in patients with unsupported aortic crossclamping. We conclude that support of the distal circulation during thoracic aortic crossclamping stabilizes hemodynamics and prevents systemic acidosis and renal ischemia. Further, our data suggest that the centrifugal pump may provide better protection than a passive shunt.     

Simultaneous repair of arch and abdominal aortic aneurysms

Objective: Atherosclerotic aneurysms in the aortic arch are associated with abdominal aortic aneurysms in up to 37% of cases. We have developed a single-stage approach to the repair of both aneurysms using a temporary bypass. Subjects: Since November 1996, 5 patients underwent simultaneous repair of aneurysms in the aortic arch and in the infrarenal abdominal aorta, using a new temporary bypass graft technique. Entire arch replacement with simultaneous abdominal aortic aneurysmectomy was performed in one patient. The other 4 patients underwent distal hemiarch replacement distal from the orifice of the brachiocephalic artery with simultaneous repair of the abdominal aortic aneurysm. Method: For the entire arch replacement procedure, blood flow to all major branches of the aortic arch was established using a bifurcated graft. This graft anastomosed to the ascending aorta was used as the proximal inflow of the temporary bypass graft. For the hemiarch replacement procedure, the proximal inflow segment of the temporary bypass graft was anastomosed to the brachiocephalic artery. In both cases, the distal outflow segment of the temporary bypass graft was the graft used for repair of the abdominal aortic aneurysm. In order to prevent any clamp injury, Teflon felt was tightly wrapped around the aorta before the clamp was applied. Results: Evaluation of the hemodynamic parameters measured during cross-clamping of the aortic arch revealed stable distal perfusion to the visceral organs and no excessive increase in cardiac afterload. All patients had an uneventful postoperative course and were discharged within 1 month of surgery. Conclusion: Our temporary bypass method is recommended for simultaneous replacement of aneurysms in the aortic arch and the abdominal aorta.     

Distal arch aneurysm repair using stent-grafting and ascending aorto-left axillary bypass

Background. Transcatheter application of a stent-graft to the angulated aortic segments with critical side branches poses some problems. We report our technique of distal arch aneurysm repairs using stent-grafts inserted through the aortic arch and ascending aorto-axillary bypass.

Patients and Results. Three patients underwent successful distal arch aneurysm repair using a homemade semiflexible stent-graft placed under hypothermic circulatory arrest. The left subclavian artery was reconstructed by an extraanatomic bypass grafting between the ascending aorta and left axillary artery. Postoperative imaging demonstrated reduction of aneurysm size and no endoleaks from an intercostal artery.

Conclusions. Our technique seems to be useful for repair of distal arch aneurysms and is a less invasive procedure.     

Simultaneous repair of arch and abdominal aortic aneurysms. A simple new technique using a temporary bypass graft.

OBJECTIVE: Atherosclerotic aneurysms in the aortic arch are associated with abdominal aortic aneurysms in up to 37% of cases. We have developed a single-stage approach to the repair of both aneurysms using a temporary bypass. SUBJECTS: Since November 1996, 5 patients underwent simultaneous repair of aneurysms in the aortic arch and in the infrarenal abdominal aorta, using a new temporary bypass graft technique. Entire arch replacement with simultaneous abdominal aortic aneurysmectomy was performed in one patient. The other 4 patients underwent distal hemi-arch replacement distal from the orifice of the brachiocephalic artery with simultaneous repair of the abdominal aortic aneurysm. METHOD: For the entire arch replacement procedure, blood flow to all major branches of the aortic arch was established using a bifurcated graft. This graft anastomosed to the ascending aorta was used as the proximal inflow of the temporary bypass graft. For the hemi-arch replacement procedure, the proximal inflow segment of the temporary bypass graft was anastomosed to the brachiocephalic artery. In both cases, the distal outflow segment of the temporary bypass graft was the graft used for repair of the abdominal aortic aneurysm. In order to prevent any clamp injury, Teflon felt was tightly wrapped around the aorta before the clamp was applied. RESULTS: Evaluation of the hemodynamic parameters measured during cross-clamping of the aortic arch revealed stable distal perfusion to the visceral organs and no excessive increase in cardiac afterload. All patients had an uneventful postoperative course and were discharged within 1 month of surgery. CONCLUSION: Our temporary bypass method is recommended for simultaneous replacement of aneurysms in the aortic arch and the abdominal aorta.     

Spinal Cord Protection in the Absence of Collateral Circulation: Meta-Analysis of Mortality and Paraplegia

A meta-analysis of paraplegia complicating aortic surgery on patients having neither intercostal nor spinal collaterals, epitomized by patients with acute traumatic aortic rupture, was done. Index Medicus and Medline were searched for all suitable English publications between 1972 and 1992. New paraplegia occurred in 9.9% of 1492 patients who underwent surgery. However, 19.2% of patients undergoing surgery with only simple aortic cross-clamping developed paraplegla, in contrast to 6.1% if distal aortic perfusion was augmented by either “passive” or “active” methods (p < 0.00001). The risk of paraplegia increased progressively as cross-clamp times lengthened if simple aortic cross-clamping was used (p < 0.00001), but only once did the cross-clamp time exceed 30 minutes (p < 0.05). Paraplegia occurred in 8.2% of patients with “passive” shunts from the ascending aorta (p < 0.001 vs simple cross-clamping). Shunts from the left ventricular apex, however, had an incidence of paraplegia of 26.1% and, therefore, did not decrease the risk of paraplegia. “Active” augmentation of distal perfusion had the lowest risk of paraplegia: 2.3% (p < 0.00001 vs simple cross-clamping or “passive” shunts). Mortality, however, was higher in these potentially polytraumatized patients when they were perfused distally using methods requiring full systemic heparinization (18.2%), compared to mortality with methods not requiring heparin (11.9%; p < 0.01). In conclusion, simple aortic cross-clamping has a high risk of paraplegia if the cross-clamp time extends beyond 30 minutes. “Active” modalities of augmenting distal perfusion provide optimal spinal protection. (J Card Surg 1994;9:685–691)     

Stroke in surgery of the arteriosclerotic descending thoracic aortic aneurysms: influence of cross-clamping technique of the aorta.

OBJECTIVE: The risk of stroke caused by dislodgment of loose atheromatous plaque or mural emboli is increased by cross-clamping of the aorta. Some patients undergo descending thoracic aortic aneurysm repair with proximal aortic cross-clamping between the left common carotid artery and the left subclavian artery. The objective of this study was to determine the influence of proximal aortic cross-clamping in arteriosclerotic aneurysm or dissecting aneurysm repair. METHODS: Between May 1984 and May 2003, 81 patients underwent elective surgery for distal arch or descending aortic aneurysm repair with proximal aortic cross-clamping between the left common carotid artery and the left subclavian artery. To evaluate the influence of the proximal aortic cross-clamping, patients were divided into two groups: patients who had undergone arteriosclerotic aneurysm repair (group I, n=25) and patients who had undergone dissecting aneurysm repair (group II, n=56). RESULTS: Eight (9.9%) of the 81 patients had a stroke. Six strokes occurred in operations for arteriosclerotic aneurysm repair group I and two strokes occurred in operations for dissecting aneurysm repair group II (24 vs 3.6%; p=0.009). In-hospital mortality rates were 12% in group I and 8.9% in group II (p=0.70). Major postoperative complications included renal failure requiring hemodialysis (in 4.2% of the patients in group I and in 8.3% of the patients in group II, p=0.99) and pulmonary complication (in 20% of the patients in group I and in 16% of the patients in group II, p=0.67). CONCLUSION: Cross-clamping between head vessels should be avoided if at all possible when operating on patients who have arteriosclerotic descending thoracic aneurysms.     

Early and late results following repair of dissections of the descending thoracic aorta

Management of dissections of the descending thoracic aorta remains controversial, especially with regard to timing and method of repair. To clarify these and other issues we have reviewed our total experience with repair of descending aortic dissections between 1962 and 1983. The 44 men and 20 women had a mean (+/- SEM) age of 59 +/- 2 years (range, 19 to 83 years), and in all patients the dissection originated in and was limited to the aorta distal to the left carotid artery (Stanford type B, DeBakey types IIIa and IIIb). Twenty-nine patients underwent operation within 2 weeks of the onset of symptoms (acute), and the remainder had later repair (chronic). During repair, circulation distal to the aortic cross-clamp was supported with cardiopulmonary bypass or shunt in two thirds of patients. Overall, 18 deaths occurred less than or equal to 30 days postoperatively (operative risk 28%), and risk was higher in acute (45%) than in chronic (14%) dissections. Operative risk was not significantly related to protection of the distal circulation. The most serious postoperative complication was spinal cord ischemia manifested by paraplegia in five patients (8%) and transient or permanent paraparesis in six patients (9%). Risk of spinal cord ischemia was significantly lower in patients who had protection of the distal circulation during operative repair (8% vs. 44%, p = 0.003). Late survival, including hospital deaths, was 49% +/- 7% at 5 years after operation; 22 of the 46 patients who survived repair were found to have aneurysms involving the thoracic and/or abdominal segments of the aorta. Our results indicate that repair of chronic dissection of the thoracic aorta has a lower operative risk than repair of acute dissections, and initial medical management of acute dissection may be indicated if no early complications occur. Risk of spinal cord ischemia is significantly reduced by cardiopulmonary bypass or shunt and is preferred over aortic cross-clamping alone. Finally, these patients require careful long-term follow-up because of the high incidence of residual or recurrent aortic aneurysms.     

A novel two-stage surgical approach for the treatment of symptomatic supra-aortic artery aneurysms

We describe the case of a 45-year-old man with a unique constellation of supra-aortic artery aneurysms detected by chest X-ray during work-up for chronic cough. During his diagnostic work-up, the patient suffered an embolic stroke likely secondary to disrupted plaque originating in an aneurysmal right vertebral artery. Endovascular repair was not a viable option due to the diffuse and bilateral nature of aneurysmal disease, including involvement of the innominate and right carotid and vertebral arteries. The patient was successfully treated with a two-stage open surgical approach involving an initial right carotid artery to vertebral artery bypass and subsequent in situ reconstruction utilizing a bifurcated Dacron graft sewn to the proximal aortic arch with distal extension to the right common carotid and axillary arteries.     

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. I. Relationship of aortic cross-clamp duration, changes in somatosensory evoked potentials, and incidence of neurologic dysfunction

To determine if intraoperative monitoring of somatosensory evoked potentials detects spinal cord ischemia, we subjected 21 dogs to aortic cross-clamping distal to the left subclavian artery. Group I animals (short-term studies, n = 6) demonstrated decay and loss of somatosensory evoked potentials at 8.5 +/- 1.1 minutes after aortic cross-clamping. During loss of somatosensory evoked potentials, significant decreases in spinal cord blood flow occurred in cord segments below T6. Significant reactive hyperemia occurred without normalization of somatosensory evoked potentials after reperfusion. Fifteen Group II animals (long-term studies) were studied to determine the relationship between duration of spinal cord ischemia (evoked potential loss) and subsequent incidence of paraplegia. Extension of aortic cross-clamping for 5 minutes after loss of somatosensory evoked potentials in six dogs resulted in no paraplegia (mean cross-clamp time 12.7 +/- 0.6 minutes). Prolongation of aortic cross-clamping for 10 minutes after evoked potential loss in nine dogs (mean cross-clamp time 17.6 +/- 0.6 minutes) resulted in a 67% (6/9) incidence of paraplegia 7 days postoperatively (p = 0.02 versus 10 minutes of aortic cross-clamping). These findings demonstrate that simple aortic cross-clamping uniformly results in spinal cord ischemia and that such ischemia is detectable by monitoring of somatosensory evoked potentials. Duration of ischemia, as measured by the time of evoked potential loss during the cross-clamp interval, is related to the incidence of postoperative neurologic injury.     

Modular branched stent graft for endovascular repair of aortic arch aneurysm and dissection

PURPOSE: We describe a modular stent graft for use in endovascular repair of aneurysms of the aortic arch. METHOD: Carotid-carotid and left carotid-subclavian bypass grafts are created surgically. Two large, fully stented grafts are inserted endoluminally. The proximal component is bifurcated, with a wide proximal trunk and two distal limbs, one long and narrow, the other short and wide. This component is inserted through the carotid artery and deployed with the trunk and short wide limb in the ascending thoracic aorta; the long narrow limb opens into the innominate artery. After delivery system removal and carotid artery repair, a distal component is inserted through a femoral approach to bridge the gap between the short, wide distal limb of the proximal component and the nondilated descending thoracic aorta. The result is a branched stent graft, implanted proximally into the ascending aorta and distally into the innominate artery and descending thoracic aorta. CONCLUSION: The system has been used successfully to treat a large wide-necked pseudoaneurysm of the aortic arch.     

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     

Experiences of intentional carotid stenting in endovascular repair of aortic arch aneurysms--two case reports.

Endovascular repair of thoracic aneurysms has emerged as an attractive alternative especially in patients at high risk. However, the left common carotid artery limits the use of stent-grafts in aneurysms located in the aortic arch or close to the left subclavian artery. We report two cases with aneurysms in the distal arch and proximal descending aorta, where we have used a carotid stent in juxtaposition to an aortic stent-graft, to gain a longer proximal neck in the aortic arch in an attempt not to rely only on a by-pass graft feeding the left carotid artery.