Intraluminal Shunt Research Articles

A Modified Combined Approach to Operative Carotid and Coronary Artery Disease: 82 Cases in 8 Years

A significant number of patients undergoing coronary artery surgery have severe carotid artery disease. It is also true that up to half of the patients undergoing carotid endarterectomy (CEA) have severe treatable coronary lesions. This study aims to review data regarding 82 patients of combined approach in 8 years; the second half consists of 44 patients whose CEA was performed under local anesthesia. It compares results of the conventional and the modified approaches to simultaneous surgery. All 82 patients who planned to have a concomitant procedure were recorded prospectively between 1995 and 2003. From 1998, the surgical technique has been modified to switch to local anesthesia for CEA, rather than perform under a single general anesthetic period. All pre-and perioperative data as well as in-hospital and outpatient control (mid- to long-term) data were recorded. A P-value of less than .05 was considered as significant. Analysis of survival was performed by using the Kaplan-Meier method and the log-rank test. The 30-day follow-up was 100% complete for all patients. All patients were followed for 59.59 to 114 months) months postoperatively. Three patients (6.8%) in the modified and 2 (5.2%) in the standard group had intraluminal shunting (P > .05). In the standard group, 3 patients expired and 3 had perioperative stroke; only 1 patient had a stroke in the modified group and two expired (P > .05). Mean survival time according to Kaplan-Meier test was 109.97, SE 2.84, 95% CI (104.41-115.52) months for the former group, whereas it was 62.79, SE 1.20, 95% CI (60.4565.13) months for the latter. Actuarial estimates of survival during ten-year follow up were 94.44% SE 3.83 in ten-year follow-ups and 97.67% SE 2.30 in 5-year follow-ups for the modified group (P > .05). Avoidance from extended periods of general anesthesia and cardiopulmonary bypass periods as well as immediate recognition of impaired cerebral flow during CEA and the time it provides to take preventive measures are the most important benefits of the modified technique without significantly changing hospital and long-term mortality and stroke. It may also reduce the cost and the waiting period for the suffering patient.

Intraluminal coronary shunting preserves regional myocardial perfusion and function.

Coronary artery hemostasis during offpump coronary artery bypass (OPCAB) may be achieved with extraluminal coronary occlusion or intraluminal coronary shunting. We sought to determine with a normal porcine beating-heart model whether coronary shunting preserves regional myocardial perfusion and function compared with coronary occlusion. Six pigs (50-60 kg) underwent sternotomy and instrumentation. Two pairs of ultrasonic crystals were placed in the distribution of t h e left anterior descending (LAD) and left circumflex (LCx) arteries for measurement of fractional change in area (FCA), an index of regional contractility. Regional myocardial blood flow (RMBF) was determined with radiolabeled microspheres. Data were recorded for each animal at baseline and after LAD arteriotomy and vascular control with (1) a 1.5-mm intraluminal shunt, (2) proximal occlusion, and (3) proximal and distal occlusion. One pig experienced ventricular fibrillation during LAD manipulation and was excluded from the study. Data were summarized for the remaining 5 animals. Coronary shunting maintained RMBF and function (FCA) compared with baseline. Proximal occlusion led to 50% (P =.05) and 47% (P =.04) decreases in RMBF and FCA, respectively, in the LAD region. Proximal and distal occlusion led to 55% (P =.03) and 51% (P = 02) decreases in RMBF and FCA, respectively, in the LAD region. There were no significant changes in RMBF or FCA in the LCx (control) region. Intraluminal coronary shunting is capable of preserving distal myocardial perfusion and function in a normal porcine heart. Coronary occlusion, in contrast, significantly reduces regional perfusion and function. More frequent use of intracoronary shunting may facilitate OPCAB by minimizing ischemia and hemodynamic compromise.

Intraoperatives Monitoring in der Gef��chirurgie

Despite the variety of possibilities to evaluate hemodynamics, ultrasound-in particular duplex sonography-is the method of choice. With an increasing number of endovascular procedures, intraoperative angiograms will remain indispensable. The method of angioscopy is reserved for individual cases. Indirect monitoring in carotid surgery will keep its significance. This includes measuring somatic evoked potentials as well as transcranial duplex sonography, with regard to the increasing importance of plaque morphology and possible neurological consequences. The general recommendation of applying at least one intraoperative control method is necessary in carotid surgery, even if intraluminal shunts are routinely implanted. In addition, quality control of the peripheral vascular system should be sufficiently documented by using one or more methods of examination. So far, in prospective randomized trials, results have not improved by applying intraoperative monitoring methods. Nevertheless, they are indispensable for the careful vascular surgeon and can help to avoid complications and revision with worse prognosis in some cases.

New Intraluminal Coronary Shunt Tube for Off-Pump Coronary Artery Bypass Grafting

Purpose In cooperation with JMS Co., Ltd. (Hiroshima, Japan), we have developed a new intraluminal coronary shunt tube to allow easier, safer, and more accurate off-pump coronary artery bypass grafting (OPCABG). Description Between September 2000 and July 2002, the new shunt tube was used in 100 consecutive patients undergoing OPCABG. Patient characteristics, experimental data, and clinical results for our new shunt tube are provided. Evaluation Our new coronary shunt tube was easily implanted in nearly all (97.2%) target vessels during reconstructions. All 100 cases were performed completely during off-pump operation. Early postoperative coronary angiography was performed in all 100 cases, demonstrating excellent patency in arterial grafts (99.5%) and venous grafts (96.2%). The shunt tube displayed good flow rates under experimental conditions according to diameter, and effectively prevented ischemia during coronary arterial reconstructions in all cases. No target vessels were injured on insertion or removal of shunt tubes. Neither perioperative complications nor hospital deaths were encountered. Conclusions This new shunt tube improves the safety, accuracy, and ease of OPCABG surgery.

Chronic ultrastructural effects of temporary intraluminal shunts in a porcine off-pump model

Background Temporary intraluminal shunts (TILS) are routinely used in off-pump revascularization to facilitate the anastomosis while maintaining myocardial blood supply. Whereas tourniquet-occlusion can cause vessel wall trauma, potentially adverse chronic effects of TILS on the coronary intima have not been evaluated yet. This chronic large animal study investigated ultrastructural effects of TILS on the vessel wall. Methods Four groups of acute and chronic pigs with either tourniquet-occlusion (TOUR) or TILS (40 kg; acute, n = 12; chronic, n = 20) were analyzed. Animals underwent median sternotomy, heparin (150 U/kg) administration, and left anterior descending coronary artery exposure. In groups with TOUR the left anterior descending coronary artery was temporarily occluded (10 minutes) with a tourniquet. In groups with TILS a silicone shunt (1.5 mm diameter, 12 mm length) was placed in the left anterior descending coronary artery more than 10 minutes and then removed, and the insertion was repaired. Thirty minutes after reperfusion all acute animals were sacrificed whereas chronic animals were extubated, maintained for 3 months, and then sacrificed. The left anterior descending coronary artery regions of occlusion or placement of the TILS silicone bulbs were examined histopathologically by scanning and transmission electron microscopy by a blinded pathologist. Results In both acute and chronic investigations animals in the TILS group exhibited significantly less morphologic damage than animals in the TOUR group. In the acute phase significantly more loss of cell junction ( p = 0.037), loss of endothelium ( p = 0.032), and intimal edema ( p = 0.037) in the TOUR group than in the TILS group was observed. Three months later, characteristic features with a changed pattern were detected: vacuolization of the cell ( p = 0.03), loss of cell junction ( p = 0.042), and removal of basal membrane ( p = 0.046) as well as extensive loss of endothelium ( p = 0.003) in the TOUR group compared with the TILS group. Conclusions Intimal lesions occur with both maneuvers early and late. However, animals in the TOUR group exhibited injuries significantly more often and more severely. Therefore, acute and chronic intimal integrity of the coronary vessel may be better preserved using TILS and may thus have a positive impact on the extent of de novo stenosis and long-term prognosis of the revascularized region.

Blunt popliteal artery injury with complete lower limb ischemia: is routine use of temporary intraluminal arterial shunt justified?

Objective Complete lower limb ischemia as a result of blunt popliteal artery injury is associated with the highest morbidity and amputation rates among all of the peripheral vascular injuries. The purpose of this study was to determine the possible benefits of routine use of a temporary intraluminal arterial shunt in patients with complete limb ischemia from blunt popliteal trauma. Patients and methods Over 3 years seven blunt popliteal artery injuries with complete lower limb ischemia were managed with insertion of a shunt at the initial phase of the operation. Data from these procedures was analyzed and compared with retrospectively collected data for 10 injuries with complete ischemia treated without shunts during the preceding 5 years. Results Mean injury severity score and mangled extremity severity score were 9.3 ± 3.49 and 5.7 ± 0.95, respectively, in the shunt group, and 9.9 ± 3.57 and 5.9 ± 0.56, respectively in the non-shunt group. Mean ischemic time was 244.3, 24.3, and 268.6 minutes, respectively, for preoperative, intraoperative, and total ischemic time in the shunt group, and 273, 56.5, and 329.5 minutes in the non-shunt group. The difference was significant for intraoperative ( P < .001) and total ( P < .05) ischemic time. In the entire group, 92.8% of patients with total ischemic time greater than 4 hours underwent fasciotomy, 100% required repeat operation, and 57.1% had complications and required fasciotomy wound debridement. All patients (100%) with ischemic time greater than 6 hours required amputation, compared with no patients with ischemic time less than 5 hours. One patient in the shunt group (14.3%) experienced one fasciotomy wound complication (11.1%), compared with seven patients in the non-shunt group (70%) had 8 complications (88.9%) ( P < .05). Mean number of repeat operations was 0.8 ± 1.06 in the shunt group, and 1.9 ± 0.73 in the non-shunt group ( P < .05). One patient in the shunt group (14.3%) required fasciotomy wound debridement, compared with seven patients in the non-shunt group (70%; P < .05). Mean hospital stay was 14.4 and 23 days, respectively, in the shunt and non-shunt groups ( P < .05). Four limbs in the non-shunt group (40%) required amputation, compared with 100% limb salvage in the shunt group. Conclusion Temporary arterial shunting after blunt lower limb trauma significantly reduces total ischemic time, complications, repeat operations, amputation, and hospitalization. I recommend routine use of shunts in blunt popliteal artery injuries with complete lower limb ischemia.

Management and short-term patency of lower extremity venous injuries with various repairs

Background Although several methods of repair of extremity venous injuries have been shown to be efficacious, patency rates have varied significantly from center to center. Methods A retrospective review was made of treatment outcomes of adult and pediatric patients with major venous injuries of the lower extremity. Results From 1997 to 2002, 82 patients sustained 86 major lower extremity venous injuries. Venous injuries were treated with primary repair in 27, complex repair in 37 (autogenous vein, 10, and ringed polytetrafluoroethylene [PTFE], 27) and ligation in 20. Prior to repair, temporary intraluminal venous shunts were used in 18 patients. Follow-up duplex imaging or venography or both were performed on 42 extremities at a mean of 10.9 ± 7.1 days after repair with an overall patency rate of 73.8% (primary repair 76.5%; autogenous vein graft 66.7%; and PTFE 73.7%). Conclusions Overall early patency rate of venous repairs performed by an experienced trauma team is similar irrespective of the type of repair. The use of temporary intraluminal shunts is acceptable in selected circumstances, while ringed PTFE grafts are reasonable alternatives when the contralateral saphenous vein is too small.

Acute effects of tourniquet occlusion and intraluminal shunts in beating heart surgery.

MIDCAB and OPCAB revascularization is currently performed with temporary tourniquet occlusion of the coronary artery to achieve a bloodless surgical field. However, a trauma of the vessel wall due to snaring sometimes occurs. The use of temporary intraluminal shunts (TILS) have recently been advocated as an alternative. The aim of this experimental study was to evaluate the acute ultrastructural effects of TILS versus tourniquet occlusion on the coronary vessel wall. Twelve pigs (40+/-3 kg) were investigated. In group A (n=6) the left anterior descending (LAD) artery was temporarily occluded with a tourniquet over 20 min. In group B (n=6) a commercially available silicone TILS (1.5-mm diameter, 12-mm length, AnastaFlo, Research Medical Inc.) was placed in the LAD. After 20 min perfusion the TILS was removed and the insertion was repaired. After 30 min reperfusion all animals were killed. Three LAD territories of each animal were examined histopathologically by scanning electron microscopy (SEM), light microscopy (LM) and transmission electron microscopy (TEM). Areas of occlusion or placement of the TILS olives were investigated. SEM revealed ultrastructural alterations in both groups. While marked intimal rupture appeared in all animals of group A, only two of the six animals of group B exhibited superficial endothelial abrasions. LM showed differences of intimal thickness in all groups while TEM revealed severe edema of subendothelial tissue in four of six animals in group A. The intimal lesions observed after tourniquet occlusion in our experimental off-pump surgery model confirmed other recent studies. In contrast, utilization of TILS caused only minor damage of the vessel wall. The endothelial abrasions detected in this group may be a consequence of micro-dislocations or insertion maneuvers. Chronic studies are necessary to verify as to whether the mild injury after TILS insertion will result in a reduction or even absence of de-novo stenoses compared with tourniquet occlusion.

Cannulation of the left common carotid artery for proximal aortic repair

The proper selection of a suitable arterial cannulation site is of great importance in aortic surgery, especially in the presence of dissection. The use of the common carotid artery for the arterial inflow offers the possibility of antegrade flow during cardiopulmonary bypass and selective cerebral perfusion during aortic arch repair. Clinical Summary I have used this technique in 6 patients in whom a femoral cannulation was not feasible. The heart and the proximal aorta were exposed through a median sternotomy. After mobilization of the innominate vein, the proximal segments of the arch vessels were isolated (the left common carotid artery up to a length of 3 to 4 cm). In only 1 case with extensive dissection of the aorta including all supraaortic branches, the left common carotid artery was prepared via a separate incision in the neck. After heparinization, the exposed segment of the carotid artery was crossclamped; a longitudinal incision was carried out; and an 8- or 10-mm vascular polyester graft was anastomosed to the artery with a continuous 5-0 polypropylene suture. For this purpose, a piece of a side branch of the vascular graft for later aortic replacement was used (InterGard Hemabridge with 1 side branch or InterGard Aortic Arch with 4 side branches; InterVascular, La Ciotat, France). After connection of the arterial line and cannulation of the right atrium, cardiopulmonary bypass was started with normal flow (about 2.4 L/min/m 2 of body surface). Because all 6 patients in whom this cannulation technique was used had aortic dissection (5 acute type A dissections and 1 persistent dissection after replacement of the ascending aorta in acute type A dissection), reconstruction was begun with the distal aortic repair. After the rectal temperature had fallen to about 26°C, the arch arteries were clamped as far distally as possible from their origins. The left common carotid artery was clamped immediately proximal to the cannulation site, and an incomplete circulatory arrest, with selective cerebral perfusion at a flow rate of a 500 to 1000 mL/min, was instituted without crossclamping the aorta. The perfusion pressure was limited to not more than 100 mm Hg. In addition to ice packs placed around the head, thiopental and cortisone were used for pharmacological brain protection. After resection of the aortic arch, an end-to-end anastomosis between the vascular graft and the descending aorta was carried out with a continuous 4-0 polypropylene suture (in 1 case using the elephant trunk technique). In 4 cases the arch arteries were transected distally to their origins and anastomosed end-to-end with the side branches of the aortic arch graft (InterGard Aortic Arch, InterVascular) with continuous 5-0 polypropylene sutures. After completion of the anastomoses to the left subclavian and the left common carotid artery, the clamps on both vessels were opened, the aortic arch graft clamped proximal to the reimplanted arteries, and cardiopulmonary bypass resumed with full flow. After anastomosing the brachiocephalic artery to the Dacron graft, the clamp was shifted proximally. In 2 patients the arch arteries were excised as a longitudinal patch and anastomosed with the Dacron graft (InterGard Hemabridge, InterVascular) using a continuous suture. Subsequently, proximal aortic repair was carried out using our own techniques. 1-3 A valve-sparing aortic root repair was performed in 3 patients, and complete replacement or re-replacement of the ascending aorta and the aortic valve with a self-assembled mechanical or biological composite graft was carried out in another 3 patients. Before termination of cardiopulmonary bypass, the arterial line was switched from the carotid artery to a side branch of the vascular graft. The Dacron graft anastomosed with the left common carotid artery was severed near the anastomosis and oversewn. No neurological complications occurred in any of the patients. A 67-year-old schizophrenic with acute aortic dissection in association with Marfan’s syndrome, however, had to be reintubated because of respiratory insufficiency and kept on long-term ventilation. This patient was transferred to a rehabilitation clinic, and the remaining patients were discharged home. At present, all patients are alive and well.

Giant atherosclerotic aneurysm of the left anterior descending artery

of the proximal segment of the arch vessels is necessary anyway. The preparation of a somewhat longer proximal segment of the common carotid artery is not time-consuming and normally does not require an additional surgical access. Even in cases where the intrathoracic cannulation is not possible, the carotid artery is better accessible than the axillary artery. Furthermore, its wall is not as delicate or as easily injured. Interruption of the arterial flow during crossclamping can be avoided by using an intraluminal shunt; however, this should only be rarely necessary, as the anastomosis with the graft usually takes only a few minutes. Interest in the common carotid artery as an arterial cannulation site has recently increased, although in most cases it was only used for additional perfusion of the upper half of the body with simultaneous cannulation of the femoral artery. The cannulation technique of the left common carotid artery described offers a simple installation of cardiopulmonary bypass with antegrade flow and mostly without the necessity for a separate access in addition to the median sternotomy. Furthermore, it offers the possibility of selective cerebral perfusion during extensive operations on the aortic arch. Thanks to the absence of complete interruption of the cerebral perfusion, it minimizes the risk of air embolism and avoids the disadvantages of deep hypothermia. References

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis

Background. Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome. Methods. Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively. Results. In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B. Conclusions. The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.

Routine early postoperative duplex scanning is unnecessary following uncomplicated carotid endarterectomy.

Although early postoperative duplex scanning has become routine after carotid endarterectomy (CEA), it is unclear whether the results of these scans alter clinical management. The purpose of this study was to critically examine the usefulness of early postoperative duplex scans in evaluating the ipsilateral carotid artery (for technical perfection) as well as the contralateral carotid artery (for potential velocity changes after improvements in ipsilateral flow). Consecutive patients undergoing CEA between January 1995 and June 1999 in a tertiary hospital setting were studied. Patients underwent early postoperative duplex scanning according to the discretion of the operating surgeon and the availability of the patient. In 212 patients 236 CEAs were performed with selective use of patch closure (49%), intraluminal shunting (19%), and intraoperative completion imaging studies (14%). Neurologic complications included 3 transient ischemic attacks (TIAs) (1.3%), 3 nondisabling strokes (1.3%), and 3 disabling strokes (1.3%). There was 1 30-day death from myocardial infarction. Patients were followed up for a median of 18 months (range 0-72 months). Sixty-five percent of patients undergoing uncomplicated CEA (147/227) underwent early duplex surveillance within 6 months of operation. Unsuspected sonographic abnormalities were discovered in 8 patients (5%), including 7 cases of mild internal carotid artery (ICA) stenosis (>50% by velocity criteria) and 1 case of common carotid artery (CCA) stenosis (intimal flap). None of the patients with ICA stenosis developed symptoms or required operation at any time. The CCA intimal flap was electively repaired without complication. Postoperative changes in velocity in the contralateral ICA were found in 8/48 (17%) cases. There were 3 cases of increased velocity, upgrading 1 from 0-49% to 50-79% stenosis and upgrading 2 from 50-79% to 80-99% stenosis. The latter patients both underwent uneventful contralateral CEA. There were 6 cases of decreased velocity, resulting in downgrading of stenoses from 50-79% to 0-49% (n=5) or from 80-99% to 50-79% (n=1). Only the latter patient underwent contralateral CEA; the remainder have been followed up without intervention. Early scanning appeared to offer no clinical benefit; survival and neurologic outcome were the same in the 135 patients scanned within the first 6 months as in the 68 patients whose first postoperative scan occurred later (4-year neurologic event rate 0% in both groups; patient survival with early duplex 98 +/- 1.5%, without early duplex 96 +/- 2.6%; = NS). Early ipsilateral duplex abnormalities following CEA are infrequent in asymptomatic patients and, even if found, rarely alter management. Patients with bilateral stenosis being considered for contralateral CEA should undergo repeat duplex scanning after the first operation, because of the significant rate (19%) of contralateral velocity changes induced by ipsilateral CEA.

Internal carotid artery flow volume measurement and other intraoperative duplex scanning parameters as predictors of stroke after carotid endarterectomy

Intraoperative duplex scanning (IDS) after carotid endarterectomy (CEA) has been shown to reliably identify major defects either by significant changes in peak systolic velocities or by B-mode imaging. To evaluate whether IDS could also predict postoperative strokes in technically flawless CEAs, we analyzed several hemodynamic parameters and correlated them with patient outcome. From March 2000 to February 2001, 226 consecutive primary CEAs were performed in 208 patients (120 men). Of these, 153 lesions were asymptomatic. General anesthesia and synthetic carotid artery patches were used routinely. Intraluminal shunts were used when internal carotid artery (ICA) back-pressures were <50 mm Hg (35% of cases). IDS consisted of B-mode and color-flow imaging and spectral analyses of the common, external, and internal carotid arteries. Volume flows were measured three times, and the mean flow rate was used for this study. The first set of data was analyzed when the twenty-ninth patient had the second immediate postoperative stroke. It was noted that the two patients who had postoperative strokes had mean ICA volume flows (MICAVF) of 48 mL/min and 85 mL/min. Only two additional patients had MICAVF <100 mL/min. The remaining 25 cases had MICAVF ranging from 102 to 299 mL/min, with a mean of 165 +/- 57 mL/min (+/-SD) (P <.02). Although there was a significant correlation between MICAVF and ICA peak systolic velocity (P <.01), the latter was not found to be a significant predictor of postoperative stroke. Moreover, end-diastolic velocities, resistive index, ICA diameter, and ICA back-pressure also did not correlate with neurologic events. These findings led us to change our protocol for patients with MICAVF <100 mL/min. This included a repeat set of volume flow measurements after 15 to 20 minutes, withholding the reversal of heparin, and the liberal use of completion arteriography. Of the following 197 CEAs, 26 (13%) were found to have MICAVF <100 mL/min (range 55 to 99 mL/min; mean 79 +/- 18 mL/min). Of these, five had arteriography that documented spasm of the intracranial portion of the ICA in four and a small-diameter ICA (<2 mm) in one. Except for the five cases, the remaining 21 cases had MICAVF >100 mL/min (range 105 to 158 mL/min, mean 127 +/- 20 mL/min [+/-SD]) on repeat study. Four patients with persistent ICA low flow (70 to 99 mL/min) were treated with postoperative anticoagulation. One of the last 197 patients had a stroke caused by hyperperfusion syndrome 2 weeks after operation. Overall, six of 226 cases (2.7%) required revision on the basis of abnormal B-mode imaging results or peak systolic velocities >150 cm/s. There were two common carotid artery flaps, two ICA stenoses, one ICA flap, and one localized thrombus. All six were successfully revised and had repeat normal IDS study results, and none of these patients had a postoperative stroke. IDS is helpful in identifying residual lesions or defects that may contribute to postoperative neurologic deficits. MICAVF <100 mL/min are suggestive of spasm that could lead to thrombus formation and stroke, particularly in the presence of synthetic patches. We suggest that heparin reversal should not be used unless ICA flow rates are >100 mL/min. ICA spasm is short lived in most patients undergoing CEA.

Preserved myocardial blood flow and oxygen supply-demand balance with active coronary perfusion during simulated off-pump coronary artery bypass grafting.

During off-pump coronary artery bypass surgery, concern remains about the possible myocardial injury associated with the transient occlusion and stabilization of the target vessels. Although intraluminal shunts are used to avoid ischemia during graft anastomosis, blood flow through the shunts can be affected by upstream pressure and inherent resistance, resulting in reduced blood flow during hypotension or severe proximal stenosis. In anesthetized dogs regional myocardial blood flow (microspheres), oxygen consumption, lactate extraction, and systolic shortening (sonomicrometry) were measured in the myocardium served by the left anterior descending coronary artery with native perfusion after interposition of a 2.25-mm shunt (> or = 90% of left anterior descending diameter) and during active coronary perfusion with a constant flow pump. Measurements were made under normotension and hypotension produced by partial caval occlusion to reduce arterial pressure by 50%. Interposition of the shunt reduced blood flow by 67.8%, regional oxygen delivery by 59.8%, and systolic shortening by 45.6% relative to baseline, but lactate extraction (31.0% vs 31.2%) and oxygen supply-consumption (O(2)S/myocardial oxygen consumption ratio, 2.7 +/- 0.5 vs 2.6 +/- 0.5) were comparable with baseline values. Hypotension further decreased these physiologic values and was associated with local lactate production (-67.4% extraction) and decreased O(2)S/myocardial oxygen consumption ratio (1.3 +/- 0.1). Active coronary perfusion was associated with regional blood flow, oxygen delivery, systolic shortening, and lactate extraction comparable with baseline values. In contrast to the shunt, active perfusion maintained myocardial flow, oxygen delivery, and lactate extraction during hypotension and normalized the O(2)S/myocardial oxygen consumption ratio, although systolic shortening decreased as a result of ventricular unloading. Intraluminal shunts may impede oxygen delivery to the target myocardium, which precipitates regional ischemia during transient hypotension. Active coronary perfusion provides adequate oxygen supply independent of systemic blood pressure.

Assessment of early brain damage in carotid endarterectomy: evaluation of S-100B serum levels and somatosensory evoked potentials in a pilot study.

The release of the neuronal protein S-100B into the circulation has been suggested as an early indication of cellular brain damage. The objective of this prospective pilot study was to determine S-100B serum levels in patients undergoing cross-clamping during carotid endarterectomy (CEA) and to correlate the results with the monitoring of somatosensory evoked potentials (SSEP) and the neurological short-term outcome. Arterial blood samples of 21 patients were drawn before oral intubation, cross-clamping, and unclamping, as well as before extubation and 6 hours later. Recording of SSEP was obtained during carotid occlusion and reperfusion. If loss of SSEP appeared, cerebral ischemia was assumed and an intraluminal shunt was placed. During cross-clamping, S-100B serum levels of 14 patients increased significantly from 0.05 ng/ml to 0.21 ng/ml, but returned to baseline levels after unclamping. In 5 cases, loss of SSEP amplitudes occurred but was reversed by the shunt insertion. No significant differences of S-100B serum values, neurological examination, and carotid duplex surveillance became obvious in this group when compared to the patients with undisturbed SSEP. However, 2 patients with complete disappearance of postcentral SSEP components suffered from neurological deficits in the postoperative period. S-100B serum levels remained highly elevated 6 hours after extubation (0.78 ng/ml and 0.41 ng/ml) compared to the baseline values (0.15 ng/ml and 0.07 ng/ml). During CEA a transitory increase of the S-100B serum levels appears to present an impairment of the blood-brain barrier integrity without any neurological deficits. In contrast, persistently elevated S-100B serum levels seem to be associated with transient loss of SSEP and development of neurological deficits.

Combined off-pump myocardial revascularization and carotid endarterectomy: early experience

Background. Controversy remains regarding the optimal surgical management of patients with coexisting significant carotid and coronary artery disease. The debate has deepened by the evolution of new approaches for the treatment of both coronary and carotid disease. We report our early experience with combined off-pump coronary artery bypass (OPCAB) and carotid endarterectomy (CEA) for the treatment of patients with coexisting coronary and carotid disease. Methods. Our computer database was examined to obtain patients and their demographics and clinical profiles. Operative reports were reviewed. Telephone interviews were conducted to assess follow-up status. Results. Thirteen patients underwent combined OPCAB and CEA. Average age was 71 years. The CEA was performed with intraluminal shunting and patch reconstruction. On average, 3.6 bypass grafts were performed. There were no gross neurologic complications or myocardial infarctions. Excluding an outlier, mean length of hospital stay was 8.2 days. All patients were well on follow-up (2 weeks to 16 months). Conclusions. A combined OPCAB and CEA strategy appears safe and effective. Further follow-up and experience is warranted before conclusions regarding potential benefits of this approach for staged or conventional OPCAB/CEA procedures can be made.

Cerebral monitoring in carotid surgery. Results of a questionnaire in the Federal Republic of Germany

A standardized questionnaire was used to find out if and what kind of intraoperative cerebral monitoring method, respectively, is practised for carotid surgery in Germany. Out of 351 hospitals having received the questionnaire, 251 (75.1 %) answered the questions. 43 hospitals had not performed any carotid surgery in 1998, so 208 questionnaires remained for further analysis. In 43.3 % (n = 90), hospitals did not practise any kind of cerebral monitoring. In contrast, most hospitals monitored cerebral function and/or cerebral haemodynamics, intraoperatively. Median nerve somatosensory evoked potentials (SEP; n = 60) and electroencephalography (EEG; n = 39) dominated, whereas carotid stump pressure measuring (n = 40), transcranial Doppler sonography (TCD; n = 10), cerebral venous oximetry (n = 8) and near-infrared spectroscopy (n = 4) were used less frequently. In 60 hospitals, the indication to install temporary intraluminal shunting was based primarily on monitoring results. The results of our study mirror the present practice of intraoperative cerebral monitoring for carotid surgery in Germany. SEP monitoring is preferable because this method can reveal an imminent cerebral ischaemia with high sensitivity and specifity. TCD and cerebral oximetry are less suitable for this purpose. Measuring carotid stump pressure is not recommendable to reflect the status of cerebral haemodynamics, however this method is still in frequent use. Recommendations whether to practise cerebral monitoring or not, and what method should be used for this purpose, cannot be given presently.

Six Hundred Consecutive Carotid Endarterectomies with Temporary Shunt and Vein Patch Angioplasty: Early and Long-Term Results

Purpose: This retrospective study evaluates the long-term clinical outcome and the survival of 600 consecutive carotid endarterectomies performed with a temporary shunt. All arteriotomies were closed by vein patch angioplasty. Materials and methods: Between November 1989 and November 1998, 600 isolated carotid endarterectomies (CEA) were performed in 540 patients by a uniform surgical technique at the University Clinic of Mont-Godinne. An intraluminal shunt and patch closure were systematically used. The mean age was 68 yr (ranging from 41 to 91 yr), 400 patients were men. The risk factors included hypertension in 73%, smoking history in 60%, coronary artery disease in 51% and hyperlipidemia in 35%. The indications were asymptomatic stenosis in 47%, transient ischemic attack in 40%. vertebrobasilar symptoms in 7% and stroke in 6%. Early results: The combined 30-day stroke and death rate was 0.9%. There were four deaths. The stroke and TIAs rates were 0.2% and 1.5% respectively. The incidence of early carotid occlusion was 0.5%. Cranial or cervical nerve dysfunction was identified in 6.3%. Late results: The median follow-up was 49 months with a range of 2–124 months. Cumulative survival rates at 5 and 10 yr were 92±1% and 89±2% respectively. Thirty-two patients died during long-term follow-up; the death was stroke-related in only three patients. Conclusion: Carotid endarterectomy using an intraluminal shunt and vein patch closure is a safe and effective procedure associated with low morbidity and mortality rates at short and long-term follow-up.

Six hundred consecutive carotid endarterectomies with temporary shunt and vein patch angioplasty: early and long-term results

Purpose: This retrospective study evaluates the long-term clinical outcome and the survival of 600 consecutive carotid endarterectomies performed with a temporary shunt. All arteriotomies were closed by vein patch angioplasty. Materials and methods: Between November 1989 and November 1998, 600 isolated carotid endarterectomies (CEA) were performed in 540 patients by a uniform surgical technique at the University Clinic of Mont-Godinne. An intraluminal shunt and patch closure were systematically used. The mean age was 68 yr (ranging from 41 to 91 yr), 400 patients were men. The risk factors included hypertension in 73%, smoking history in 60%, coronary artery disease in 51% and hyperlipidemia in 35%. The indications were asymptomatic stenosis in 47%, transient ischemic attack in 40%, vertebrobasilar symptoms in 7% and stroke in 6%. Early results: The combined 30-day stroke and death rate was 0.9%. There were four deaths. The stroke and TIAs rates were 0.2% and 1.5% respectively. The incidence of early carotid occlusion was 0.5%. Cranial or cervical nerve dysfunction was identified in 6.3%. Late results: The median follow-up was 49 months with a range of 2–124 months. Cumulative survival rates at 5 and 10 yr were 92±1% and 89±2% respectively. Thirty-two patients died during long-term follow-up; the death was stroke-related in only three patients. Conclusion: Carotid endarterectomy using an intraluminal shunt and vein patch closure is a safe and effective procedure associated with low morbidity and mortality rates at short and long-term follow-up.

Carotid Endarterectomy: A new Technique Replacing Internal Shunts

Carotid endarterectomy has been reported to increase the time free from cerebral ischemic events in both symptomatic and asymptomatic patients with a high grade of stenosis of the internal carotid artery. In cases in whom the compensatory circulation during the carotid clamp time is not sufficient, the use of intraluminal shunts has been proposed. However, the use of intraluminal shunts present several problems, such as the technical difficulties in positioning the shunt, the variability of time requested for the placement, the inconstancy of the blood flow during surgery, and the need to clamp off the carotid to introduce and remove the shunt. For these reasons, most operators prefer not to employ intraluminal shunts, while others do use them only in selected cases. The purpose of this work is to present, for the first time, a new type of temporary extraluminal shunt, connecting the femoral to the internal carotid artery with the interposition of a roller pump to regulate the blood flow. This method allows one to perform carotid endarterectomy without interrupting the blood flow to the brain. 407 consecutive patients, who underwent carotid endarterectomy between August 1992 and April 2000, were considered. 35 patients presented an absolutely insufficient collateral circulation, demonstrated by important modifications of the electroencephalographic monitoring during the carotid clamp time. In these patients the endarterectomy was performed using a new femoral-carotid extraluminal shunt. In all the cases in whom the femoral-carotid extraluminal shunt was positioned, the normalisation of electroencephalographic monitoring was achieved by regulating the blood flow with the interposed roller pump. The use and the placement of the shunt was simple and easy. None of the patients showed postoperative complications, except for one who had a stroke two days after surgery. The results obtained, although to be confirmed by further studies, seem to demonstrate the effectiveness of our femoral-carotid extraluminal shunt, which was simple to use and safe.