Graft Anastomosis Research Articles

Patch Aortoplasty for Proximal Anastomosis of Coronary Artery Bypass Grafts in Patients With Complex Aortic Pathology

Proximal anastomosis of conduits to the ascending aorta in patients undergoing coronary artery bypass grafting may be hazardous or impossible in the presence of complex aortic pathology. We describe a technique of the excision of a segment of the diseased aortic wall, reconstruction with a bovine pericardial patch, and attachment of the grafts to the patch. The technique was used successfully in 2 patients (ie, 1 patient with Takayasu's disease and the other with a heavily calcified aorta).

The superficial temporal artery trunk as a donor vessel in cerebral revascularization: benefits and pitfalls

The superficial temporal artery (STA) is the mainstay of donor vessels for extracranial-intracranial bypass in cerebral revascularization. However, the typically used STA anterior or posterior branch is not always adequate in its flow-carrying capacity. In this report the authors describe the use of the STA trunk at the level of the zygoma as an alternative donor and highlight the benefits and pitfalls of this revascularization option. The authors reviewed the cases of 4 patients in whom the STA trunk was used as a donor site for anastomosis of a short interposition vein graft. The graft was implanted into the middle cerebral artery to trap a cartoid aneurysm in 2 patients, and the posterior cerebral artery for vertebrobasilar insufficiency in the other 2. Discrepancies in size between the interposition vein and STA trunk were compensated for by a beveled end-to-end anastomosis or by implanting the STA trunk into the vein graft in an end-to-side fashion. Intraoperative flow measurements confirmed the significantly higher flow-carrying capacity of the STA trunk (54-100 ml/minute) compared with its branches (10-28 ml/minute). The STA trunk interposition graft has several advantages compared with an interposition graft to the cervical carotid, including a shorter graft and no need for a neck incision. However, in the setting of ruptured aneurysm trapping, with the risk of subsequent vasospasm, it is a poor conduit for endovascular therapies. The STA trunk is a valuable donor option for cerebral revascularization, but should be avoided in the setting of subarachnoid hemorrhage.

Expression of Hypoxia Inducible Factor–1α, Macrophage Migration Inhibition Factor, Matrix Metalloproteinase–2 and −9, and Their Inhibitors in Hemodialysis Grafts and Arteriovenous Fistulas

It is well recognized that arteriovenous fistulas (AVFs) used for hemodialysis access have better primary patency rates with less restenosis than polytetrafluoroethylene (PTFE) grafts; however, the mechanism responsible for this is not known. Recent data suggest that hypoxia inducible factor-1 alpha (HIF-1 alpha) is associated with vascular restenosis, possibly through mechanisms that increase the production of macrophage migration inhibition factor (MIF), matrix metalloproteinase-2 (MMP-2) and MMP-9, and their inhibitors (tissue inhibitor of MMPs; TIMP). The present study tested the hypothesis that there are differences in the expression patterns of HIF-1 alpha, MIF, MMP-2, MMP-9, and TIMPs in specimens removed from patients with AVFs and PTFE grafts. Whole-vessel tissue samples were obtained from the vein distal to the vein-to-PTFE graft anastomosis and the proximal outflow vein (within 6 cm of the arteriovenous anastomosis) of AVFs from 17 patients who required a surgical revision for thrombosis and stenosis. Nonstenotic veins of four patients undergoing hemodialysis vascular access placement were used as controls. PTFE grafts (n = 6), AVFs (n = 6), and control samples (n = 3) underwent Western blot analysis and zymography. A separate group of five patients with PTFE hemodialysis grafts and one control subject were used for immunohistochemical analysis. Specimens from patients with PTFE grafts had significantly higher expression of HIF-1 alpha (P = .03), MIF (P = .02), TIMP-1 (P = .0006), pro-MMP-2 (P = .02), and pro-MMP-9 (P = .046) compared with control veins. The expression of only pro-MMP-9 was significantly higher in AVFs compared with control samples (P = .004). There was a significant increase in the expression of MIF (P = .007) and TIMP-1 (P < .0001) in PTFE graft specimens compared with AVFs. MIF and TIMP-1 were localized to the adventitia of the vein distal to the vein-to-PTFE graft anastomosis. There were major differences in the expression patterns of hypoxia (ie, HIF-1 alpha) and proteins regulated by HIF-1?, including MIF, pro-MMP-2, pro-MMP-9, and TIMP-1, in specimens removed from patients with PTFE grafts and AVFs. Understanding the role of HIF-1 alpha and these proteins in hemodialysis access failure can help improve outcomes.

A mathematical model of venous neointimal hyperplasia formation.

BackgroundIn hemodialysis patients, the most common cause of vascular access failure is neointimal hyperplasia of vascular smooth muscle cells at the venous anastomosis of arteriovenous fistulas and grafts. The release of growth factors due to surgical injury, oxidative stress and turbulent flow has been suggested as a possible mechanism for neointimal hyperplasia.ResultsIn this work, we construct a mathematical model which analyzes the role that growth factors might play in the stenosis at the venous anastomosis. The model consists of a system of partial differential equations describing the influence of oxidative stress and turbulent flow on growth factors, the interaction among growth factors, smooth muscle cells, and extracellular matrix, and the subsequent effect on the stenosis at the venous anastomosis, which, in turn, affects the level of oxidative stress and degree of turbulent flow. Computer simulations suggest that our model can be used to predict access stenosis as a function of the initial concentration of the growth factors inside the intimal-luminal space.ConclusionThe proposed model describes the formation of venous neointimal hyperplasia, based on pathogenic mechanisms. The results suggest that interventions aimed at specific growth factors may be successful in prolonging the life of the vascular access, while reducing the costs of vascular access maintenance. The model may also provide indication of when invasive access surveillance to repair stenosis should be undertaken.

Blood Flow in End-to-Side Anastomoses

Blood flow in end-to-side autogenous or prosthetic graft anastomoses is of great interest to biomedical researchers because the biomechanical force profile engendered by blood flow disturbances at such geometric transitions is thought to play a significant role in vascular remodeling and graft failure. Thus, investigators have extensively studied anastomotic blood flow patterns in relation to graft failure with the objective of enabling the design of a more optimal graft anastomotic geometry. In contrast to arterial bifurcations, surgically created anastomoses can be modified to yield a flow environment that improves graft longevity. Understanding blood flow patterns at anastomotic junctions is a challenging problem because of the highly varying and complex three-dimensional nature of the geometry that is subjected to pulsatile and, occasionally, turbulent flow.

Assessment of Long-Term Consequences of Composite Bentall and Aortic Valve Replacement using Dual-source 64-slice Multi-detector Computed Tomography

Background: During composite aortic root and valve replacement (Bentall operation), the ‘button’ technique is commonly performed whereby a cuff of native aorta is implanted, together with the coronary ostium, into the aortic graft. The coronary-aortic and aorto-aortic graft anastomoses features years post-surgery are not well-described. We have studied the multi-detector (64-slice, dual-source) computed tomography (MDCT) appearance of these anastomoses.

ＰＡＳ・Ｐｏｒｔを用いて左開胸アプローチによる再冠動脈バイパス術（ｒｅ‐ＣＡＢＧ）を施行した１例

ＰＡＳ・Ｐｏｒｔを用いて左開胸アプローチによる再冠動脈バイパス術（ｒｅ‐ＣＡＢＧ）を施行した１例

Inadvertent anastomosis of saphenous vein graft to a cardiac vein detected with coronary computed tomographic angiography

A 34-year-old man with a prior history of Hodgkin's disease and coronary artery bypass surgery for radiation-induced left main disease presented with persistent chest pain. Cardiac catheterization showed near simultaneous filling of the venous system during arterial injection and could not precisely delineate the insertion point of the vein graft anastamosis to the diagonal branch, and the patient was referred for coronary computed tomography angiography (CTA). CTA demonstrated that the anastamosis of the graft was with a cardiac vein. This case illustrates the valuable complementary role of both angiographic methodologies in confirming a complex anatomic diagnosis.

Initial clinical experience with a new end graft holder for anastomosis in coronary surgery

We assessed the feasibility and effectiveness of a novel end graft holder for coronary artery bypass grafting (CABG) and evaluated anastomotic patency and early clinical results. The end graft holder was applied to 45 consecutive patients. Operative characteristics were off-pump CABG in 22.2%, emergency in 28.9%, and concomitant cardiac surgery in 13.3%. The device was used safely without graft injury or inadequate gripping on grafts. Postoperative angiography showed that the patency rate of distal anastomosis was 96.7% (arterial, 100%; venous, 94%). All proximal aortic and composite graft anastomoses were patent without stenosis. The rate of 30-day major adverse cardiac and cerebrovascular events was 13.3% (operative deaths, 3; repeated CABG, 1; percutaneous coronary arterial intervention, 1; and cerebral infarction, 1). None of the elective patients died during hospitalization. Our initial clinical experience demonstrated that the new end graft holder was safe, reliable, and effective during CABG. The excellent fixation and visualization of the graft with the device might be particularly beneficial for off-pump CABG or for teaching trainees.

Epicardial Ultrasonography: A Potential Method for Intraoperative Quality Assessment of Coronary Bypass Anastomoses?

Intraoperative quality assessment in coronary artery bypass surgery confirms graft patency and enables revision of failing grafts. The aim of this study was to evaluate graft quality intraoperatively by epicardial ultrasonography and to compare this technique with transit time flow measurements and intraoperative angiography, and to evaluate the ability of these methods to predict long-term patency as described by follow-up angiography. Thirty-nine patients with mean age of 66 years (SD 9.5) who underwent off-pump coronary artery bypass surgery with internal mammary artery graft to the left anterior descending coronary artery were included. Epicardial ultrasonography and transit time flow measurement were performed after completion of the anastomoses, and coronary angiography after closure of the chest. Follow-up angiography was carried out after 156 days (SD 50). Diameter measurements obtained by epicardial ultrasonography correlated poorly with the same diameter measurements obtained by angiography. Epicardial ultrasonography revealed 5 abnormal grafts (13%), transit time flow measurements none, and intraoperative angiography 9 (23%). At follow-up angiography, 4 grafts (11%) were pathologic. Epicardial ultrasonography and transit time flow measurements indicated no need for graft revision; intraoperative angiography suggested need for revision in 3 cases. Epicardial ultrasonography could be a useful method for intraoperative assessment of graft anastomosis quality, but needs to demonstrate its ability to predict grafts in need of revision. Angiography must be considered the gold standard in intraoperative imaging.

How I do it: Traction of Ascending Aorta with Starfish Heart Positioner During Proximal Saphenous Vein Graft Anastomosis Using the PAS-Port System in Off-Pump Coronary Artery Bypass Grafting

The PAS-Port system allows for the rapid deployment of a clampless proximal anastomosis between a saphenous vein graft and the aorta. We have developed a simple technique of establishing traction of the ascending aorta with the Starfish heart positioner during proximal saphenous vein anastomosis using the PAS-Port system in off-pump coronary artery bypass grafting.

Reinforcement of Left Ventricular Assist Device Outflow Grafts to Prevent Kinking

Because of their small size, rotary left ventricular assist devices (LVADs) can be implanted through several alternative approaches, including transdiaphragmatic LVAD insertion through a left subcostal incision with anastomosis of the outflow graft to the retroperitoneal supra-celiac aorta and a left thoracotomy approach with anastomosis to the descending thoracic aorta. More recently we have added a counter-incision to allow the outflow graft of a transdiaphragmatic LVAD to be tunneled through the right chest and anastomosed to the ascending aorta. However, constructing a tension-free, nonkinking lie of the outflow graft can be challenging. We have found that placing a 10-cm to 15-cm length of polytetrafluoroethylene graft coaxially over the LVAD outflow graft ensures a smooth, kink-free lie. Thus far 12 patients have undergone reinforcement of the LVAD outflow graft prior to graft-to-aorta anastomosis. In all cases, graft lie was facilitated and kinking was eliminated.

Spyder Aortic Connector System in Off-Pump Coronary Artery Bypass Surgery

The Spyder aortic connector (Medtronic, Minneapolis, MN) is a new, promising connector device and its safety and efficacy have been evaluated in this study. Twenty-two patients were randomized to proximal vein graft anastomosis with the Spyder aortic connector (Medtronic) or hand-sewn technique. Twenty patients underwent multi-detector computed tomographic scans of the chest 6 months after surgery to evaluate vein graft patency. We have failed to successfully deploy three Spyder connector devices. Thus in this study we have evaluated the graft patency of 19 hand-sewn grafts and of 19 vein grafts anastomosed with the Spyder anastomotic device. Three vein grafts whose proximal anastomosis was accomplished with the Spyder anastomotic connector were occluded and all hand-sewn vein grafts were patent (16% vs 0%; p = 0.23). Stenosis of the proximal anastomosis was observed in seven vein grafts (37%), accomplished with the Spyder anastomotic connector, and in one (5%) hand-sewn vein graft (p = 0.042). The results of this study suggest that the use of the Spyder aortic connector device is associated with suboptimal 6-month graft patency.

Contemporary Management of Postcatheterization Pseudoaneurysms

A pseudoaneurysm (PSA) is a contained rupture; there is a disruption in all 3 layers of the arterial wall (Figure 1). PSAs may occur under 4 circumstances: (1) after catheterization (Figure 2); (2) at the site of native artery and synthetic graft anastomosis (eg, aortofemoral bypass graft); (3) trauma; and (4) infection (eg, mycotic PSA) (Figure 3). This review will focus on PSAs that occur after cardiac and peripheral endovascular procedures. PSAs occur when an arterial puncture site does not adequately seal. Pulsatile blood tracks into the perivascular space and is contained by the perivascular structures, which then take on the appearance of a sac. Hematoma and the surrounding tissue form the wall of the PSA. Figure 1. Artist’s rendition of a postcatheterization PSA with proper placement of the needle for thrombin injection. There is a disruption in all 3 layers of the arterial wall. In essence, this represents a contained rupture. Figure 2. Arteriogram that demonstrates an axillary artery PSA after a diagnostic arteriographic procedure. Note the disruption in the vessel wall (white arrow) and the larger PSA sac (black arrow). Figure 3. Ultrasound of a spontaneous PSA in the left brachial artery. Note the absence of a tract. The PSA chamber is directly connected to the brachial artery. This type of PSA must be treated surgically. This patient had infective endocarditis. Postcatheterization PSA is one of the most common vascular complications of cardiac and peripheral angiographic procedures. The incidence of PSA after diagnostic catheterization ranges from 0.05% to 2%.1 When coronary or peripheral intervention is performed, the incidence increases to 2% to 6%. In 1 series where diagnostic ultrasound was performed on 536 consecutive patients who underwent catheterization, the incidence of PSA was 7.7%, with 83% of the PSAs associated with interventional procedures.2 Despite a low …

Inhibition of neointimal hyperplasia in a sheep model of dialysis access failure with the bioabsorbable Vascular Wrap paclitaxel-eluting mesh

This study evaluated the effect of a bioabsorbable mesh containing paclitaxel on neointimal hyperplasia in a sheep model of dialysis access failure.Forty neutered male sheep were randomized to one of five parallel groups: no mesh; or a 3-cm x 6-cm mesh with 0.0, 0.3, 0.7, or 1.2 microg/mm(2) of paclitaxel for a total dose of 0.0, 0.6, 1.3, or 2.2 mg, respectively. Commercially available 6-mm internal diameter expanded polytetrafluoroethylene grafts were surgically placed between the left common carotid artery and the right external jugular vein. For those animals randomized to one of the mesh groups, the mesh was placed around the distal end of the graft and venous anastomosis. Patency was assessed at weekly intervals throughout the study. Animals were euthanized 8 weeks after implantation, and grafts and veins were harvested. After histologic processing, six cross sections were cut at the venous end of the graft and vessel. The primary and secondary efficacy outcome measures, respectively, were the area and capillary density of the neointima at the graft-vein anastomosis. Histologic analyses were also performed to investigate the effects of the paclitaxel-eluting mesh on the anastomotic site.Grafts occluded before the scheduled sacrifice in five animals, and they were excluded from the study and not replaced. Control animals developed significant neointimal hyperplasia at the cross section taken perpendicular to the graft at its most distal end: the neointimal area measured 10.5 +/- 6.8 mm(2) in the no mesh group and 6.4 +/- 3.2 mm(2) in the zero-dose mesh group (P = .28). In contrast, neointimal area was significantly reduced in the paclitaxel mesh groups: 0.9 +/- 1.4 mm(2) in the 0.3 microg/mm(2) group (P = .008 vs zero-dose mesh), 1.3 +/- 1.5 mm(2) in the 0.7 microg/mm(2) group (P = .004 vs zero-dose mesh), and 1.2 +/- 1.4 mm(2) in the 1.2 microg/mm(2) group (P = .008 vs zero-dose mesh). Capillary density in the neointima at the graft-vein anastomosis decreased with paclitaxel and was significantly reduced in the paclitaxel mesh groups with 0.3 and 1.2 mug/mm(2) compared with the zero-dose mesh control (3.6 +/- 2.9 vs 8.9 +/- 5.6 per mm(2) [P = .022] and 1.1 +/- 1.7 vs 8.9 +/- 5.6 per mm(2) [P = .001] respectively). The paclitaxel mesh had no significant effect on healing of the anastomosis or on the thickness of the adjacent vein.In this model, the paclitaxel-eluting mesh significantly reduced neointimal hyperplasia and neointimal capillary density without apparent toxicity to the adjacent vein.

Percutaneous Management of Complications (Aortoenteric Fistula and Sac Abscess) Following Bypass Surgery for Abdominal Aortic Aneurysm

A 45-year-old man initially presented with pulsatile abdominal swelling and uncontrolled hypertension of 3 months’ duration. He was diagnosed to have atherosclerotic abdominal aortic aneurysm, for which he underwent proximal and distal ligation of the aneurysmal aorta and aortoaortic bypass graft of the descending thoracic aorta to the infrarenal abdominal aorta with a right iliorenal bypass graft. One year after this surgery, he developed hematemesis, malena, and severe backache. Angiography revealed persistent filling of the ligated native aortic aneurymal lumen through the active leak at the proximal bypass graft anastomosis with the descending thoracic aorta (Figs.1a and 1b). A Zenith custom-made aortic stent graft (Cook Inc., Australia) was placed across the anastomosis to treat the leak (Fig. 1c). Antibiotic prohylaxis was given for a week in view of arteriotomy. The patient was asymptomatic for 1 year after the aortic stent graft placement, and subsequent follow-up imaging (CT scan) was unremarkable (Fig. 2a). Six months later, i.e., 18 months after placement of the stent graft, he developed pyrexia of unknown origin, with chills and rigors, that was not responsive to antipyretics. All the routine investigations for pyrexia of unknown origin were unremarkable. However, CT scan showed a high-density fluid collection, with an air fluid level in the native aortic aneurysmal lumen suggesting an abscess in the native aneurysmal sac (Fig. 2b). A 10-Fr pigtail drainage catheter was inserted into the abscess cavity under CT guidance (Figs. 3a and b). It drained frank greenish pus, microscopic examination of which showed enterococci. Daily intracavitary antibiotic flushes of chloramphenicol and gentamycin were given through the drainage catheter for 3 weeks, along with parenteral antibiotics. The fever subsided and the drain output decreased gradually. Repeat CT scan, once the drain output was nil and the patient had become asymptomatic, showed a collapsed native aortic aneurysmal cavity with no residual pus (Fig. 3b). The patient remained symptom-free at 1-year clinical and imaging follow-up.

Aortic Pseudoaneurysm with Fistulization into the Pulmonary Artery: A Cause of Refractory Heart Failure After Bentall Procedure

We present the case of a patient who developed left-sided congestive heart failure several years after undergoing composite graft surgery for annuloaortic ectasia and aortic regurgitation. Transthoracic echocardiography showed markedly elevated left ventricular filling pressures and severe pulmonary hypertension. However, no underlying pathology or anatomic abnormality to explain the high filling pressures could be identified. On transesophageal echocardiography, a large aortic pseudoaneurysm was demonstrated arising from dehiscence of the distal graft anastomosis to the native aorta. A fistulous communication was noted between the pseudoaneurysm and the right pulmonary artery resulting in a large aortopulmonary shunt. This case illustrates the inherent limitations of transthoracic echocardiography in the detection of complications after composite graft surgery of the aorta.

Duplex Ultrasound Surveillance after Axillofemoral Bypass

Objective —There are limited data available in the literature on duplex imaging after axillofemoral bypass grafting. We sought to explore this topic and identify duplex findings predictive of graft failure. Methods —All patients who underwent axillo-femoral or bifemoral prosthetic bypass procedures during an 9-year period and returned for follow-up duplex ultrasound scans (U/S) were included. Protocol based testing included ankle brachial indices, toe pressures, and duplex velocities at proximal anastomosis, mid-axillary graft, and femoral anastomosis sites. Results —Forty-seven patients underwent axillo-femoral bypass prosthetic procedures and returned for follow-up U/S. Mean follow-up was 61 ± 180 months (range, 1–1232) with a mean number of postoperative U/S of 4.5 per person ± 3.6 (range, 1–16). Eight bypass grafts (17%) occluded, i.e., 4 ax-bifemoral segments and 4 femoral-femoral segments. Two of eight occluded patients had not returned for postoperative U/S until occlusion occurred. Of the other 6 patients who underwent postoperative U/S before occlusion, all but one had midgraft peak systolic velocities of &lt;85 cm/sec. Considering all patients evaluated with at least one postoperative examination, midgraft axillary femoral bypass velocities were predictive of future graft failure ( p = 0.0001) with occlusion occurring in 66% (5 of 8) of those with velocities &lt;85 cm/sec, and 1 patient (1/37) with velocities &gt;85 cm/sec. Two patients had velocities &lt;85 cm/sec and remained patent. Six patients had abnormal studies (peak systolic velocities &gt;250 cm/sec) but that did not progress to failure at follow-up. One patient had a para-anasatamotic aneurysm that was identified during follow-up that was treated by endovascular grafting. Conclusion —Midgraft axillary femoral bypass velocities are predictive of future graft failure.

Internal Thoracic Vessels Used as Pedicle Graft for Anastomosis With Vascularized Bone Graft to Reconstruct C7–T3 Spinal Defects

A report of 4 cases of primary bone tumors (3 cases) or infection (1 case) at the cervicothoracic junction treated with resection-reconstruction. To document a new technique using the internal thoracic vessels as recipient vessels for reconstruction of the cervicothoracic spine with free vascularized fibula grafts. The cervicothoracic junction is a difficult region in reconstructive spinal surgery. Although nonvascularized fibula grafts can be used to reconstruct the osseous defect, compared with free vascularized fibula grafts they are biomechanical weaker, incorporate less well, are less resistant to infection, and remodel incomplete in time. However, when using free vascularized bone grafts, the selection of suitable recipient vessels remains one of the most critical decisions. Four patients who had a primary tumor (3 cases) or a severe progressive kyphotic deformity and progressive neurologic symptoms due to tuberculosis (1 case) were treated by resection and vascularized reconstruction. In 3 patients, a staged anteroposterior en bloc resection of T1-T3 (2 cases) or T1-T2 (1 case) was performed; the ventral reconstruction of the osseous defect consisted of a vascularized fibula graft interposition between C7-T4 (2 cases) or C7-T3 (1 case). In another case, an axial slot was milled through the T1-T2 vertebral bodies to accept an osteotomized vascularized fibular graft. In all cases, a free vascularized fibula graft was used: the vascular anastomosis was performed between the peroneal and the dissected and rerouted internal thoracic vessels. The anterior construction was strengthened by a ventral plate-screw system. The resection-reconstruction procedures, including the dissection, rerouting, and anastomosis between the internal thoracic vessels and the peroneal vessels, were successfully performed. At present, all patients are alive, and there is no evidence of recurrent disease, unchanged, or improved neurologic with a mean follow-up of 28 months. All grafts are well incorporated. CONCLUSIONS.: A combined low anterolateral cervical and midsternal approach or a midline sternotomy allows not only a safe and excellent exposure to the cervicothoracic junction but also to the internal thoracic vessels. The internal thoracic vessels are appropriate donor vessels: its longevity, diameter, length, and rerouting capacity allow vascularized graft reconstruction of vertebral column defects of the low cervical (C6-C7) and/or upper thoracic (T1-T3) region.

Diagnostic and Surgical Approach to a Descending Thoracic Aorta Saccular Aneurysm Case

Descending aorta saccular aneurysms are seen less than fusiform aneurysms. All symptomatic saccular aneurysms must be operated. In this study, we present a saccular aneurysm case developed at the descending aorta 1 year after a motor vehicle crash. Following an aorta-LAD saphenous vein graft anastomosis performed in beating heart, the aneurysm neck was closed with a Dacron patch under deep hypothermic circulatory arrest. All signs and symptoms removed dramatically after the operation. Regarding this case, we recommend that the surgical treatment must be performed in accordance with localization and specialties of aortic aneurysms.