Magnetic Resonance Imaging Angiography in Patency Evaluation of Bronchial Artery Revascularization Grafts

In this report we present our experience of non-invasive magnetic resonance imaging (MR) angiography and selective catheter angiography in assessing the patency of bronchial artery revascularization grafts after an en bloc double-lung and heart-lung transplantation. We studied 8 patients who had undergone pulmonary transplantation with direct bronchial artery revascularization. Catheter angiography was performed 10 days to 63 months postoperatively. MR angiography was performed within 24 h of the catheter procedure and the results were compared with the findings from catheter angiography. Catheter angiography showed the bronchial revascularization graft to be patent in 6 patients and occluded in 2. At MR angiography, the patency of bronchial artery revascularization grafts was reliably identified in 7 of the 8 patients. One patient had inadequate image quality because of void artefacts caused by haemostatic clips. It is concluded that MR angiography is a reliable method for assessing the patency of bronchial artery revascularization grafts.     

Thermal Coronary Angiography for Intraoperative Patency Control of Arterial and Saphenous Vein Coronary Artery Bypass Grafts: Results in 370 Patients

ABSTRACT Background and aim of the study: Early graft failure is often associated with technical failures and is therefore potentially avoidable. We used thermal coronary angiography (TCA) for intraoperative graft patency control in 370 patients undergoing routine coronary artery bypass graft surgery to determine whether consequent intraoperative bypass graft control may result in improved patency rates. Methods: The temperature differences generated in between the myocardium and the grafts by injecting cold cardioplegic solution into the proximal end of a vein graft or by warmer blood running through an internal thoracic artery (ITA) graft were detected using three different infrared camera systems. The resulting “heat pictures” were evaluated for anastomotic patency and to outline graft anatomy. Results: A total of 693 vein grafts were visualized. In 9.4% TCA failed to produce usable images. In the remaining 628 grafts, TCA revealed intraoperative patency in 98.8%. Out of 370 ITA grafts, only 14 could not be sufficiently visualized by TCA. Nineteen ITA occlusions (5.3%) were found: 5 intimal flaps; 11 suture imposed strictures; and 3 proximal ITA occlusions. All occluded grafts were subsequently revised or replaced. All sequential ITA as well as 15 right ITA grafts proved to have patent anastomoses. Conclusion: Using TCA an early graft dysfunction rate of 1% for vein grafts and 5.3% for ITA grafts could be demonstrated. Most occlusions were due to technical mistakes at the distal anastomosis. TCA outlines grafts and the attached coronaries by temperature differences without the need for a contrast agent. There is no interference with the surgical procedure. It is an ideal, noninvasive method to immediately document the success or failure of myocardial revascularization.     

A Review of Arterial Grafts Used for Microvascular Arterial Reconstruction

Arterial grafts are sometimes used in microvascular reconstruction and their clinical benefit over standard venous grafts is unknown. To determine arterial graft utilization in clinical microvascular arterial reconstruction, a review of the literature was done. PubMed search resulted with 4,352 finds, and after screening for relevance, 11 articles reporting on 55 arterial grafts were analyzed. All reports were retrospective studies, case reports, and case series, with no randomized controlled trials. Two retrospective series reported better patency of arterial versus venous grafts in upper-limb revascularization for chronic occlusion, but the findings were highly biased. Better patency of arterial grafts did not lead to higher rate of clinical improvement. Antiplatelet and lipid-lowering agents seem to be underused in venous graft recipients and use of no-touch venous grafting has not been reported. Based on the available data, routine use of arterial grafts cannot be recommended. Studies that show better patency of arterial grafts in hand revascularization for chronic vascular insufficiency are retrospective and biased, so a randomized controlled trial is needed.     

Influence of Aspirin and Dipyridamole on Patency of Coronary Artery Bypass Grafts

A prospective randomized trial was performed to determine if the administration of inhibitors of platelet function would improve the patency of coronary artery bypass grafts. Patients were operated on for intractable angina with angiographically demonstrable lesions. The left internal mammary artery (IMA) was used for bypass of lesions of the left anterior descending coronary artery (LAD). Saphenous vein grafts were used for the LAD if the IMA was inadequate and for all other vessels. Treated patients received 1,300 mg of aspirin and 100 mg of dipyridamole (Persantine) orally each day. Control patients received neither drug. Patients returned 3 to 6 months after operation for repeat angiography. Results were analyzed by chi-square.One hundred seventy-four patients entered the study from June, 1973, through December, 1975, and 113 were analyzed. In the control group, 66 patients had 27 IMA-LAD grafts and 93 saphenous vein grafts. In the treatment group, 47 patients underwent 18 IMA-LAD grafts and 75 saphenous vein grafts. Ninety-eight of the 120 grafts (82%) were patent in the control group, and 87 of 93 grafts (94%) were patent in the treatment group (x² = 6.34, p < 0.02). Of the 45 IMA-LAD grafts in both groups, only 1 was occluded, a patency of 98%. In the control group, 72 of 93 saphenous vein grafts (77%) were patent. In the treatment group, 69 of 75 (92%) were patent (x² = 6.54, p < 0.02). The results of the study show a 15% difference between the two groups in the early patency of saphenous vein grafts. We continue to use aspirin and dipyridamole to improve the patency of saphenous vein bypass grafts.     

Patency Rates and Complications of Exxcel Yarn-Wrapped Polytetrafluoroethylene Grafts Versus Gore-Tex Stretch Polytetrafluoroethylene Grafts: A Prospective Study

Purpose. Polytetrafluoroethylene (PTFE) has long been used for hemodialysis access when there is no suitable superficial vein. We conducted a prospective randomized study to compare two PTFE grafts; the stretch Gore-tex graft and the Exxcel graft.Methods. Between May 2000 and February 2001, PTFE grafts were implanted for hemodialysis access in the upper extremities of 94 consecutive patients with end-stage renal disease. Graft selection was randomized, with patients receiving either a Gore-tex or an Exxcel graft. All grafts were monitored for signs of thrombosis or other complications. Graft survival was analyzed using a life-table analysis and the log-rank test was applied to compare graft patency.Results. The primary patency rates 1 and 2 years after implantation were 51% and 36% for the Exxcel grafts, and 71% and 45% for the Gore-tex grafts, respectively. The difference between the two groups was not significant at any time. The incidence of complications needing further surgical management was 8.2% in the Exxcel group and 6.7% in the Gore-tex group, without a significant difference.Conclusion. Exxcel grafts or Gore-tex stretch grafts can be used for dialysis access with similar expected outcomes for up to 2 years, despite the differences in their outer surface design. The yarn-wrapped design does not appear to enhance the graft patency and we found no remarkable difference.     

Infected Abdominal Aortic Aneurysm Treated by In Situ Replacement with Cryopreserved Arterial Homograft

Infected abdominal aortic aneurysms are uncommon but not rare (1–3% of all abdominal aortic aneurysms). This life-threatening disease can lead to rapid uncontrolled sepsis and/or aortic rupture. We report one case that underlines two notions. Firstly computed tomography is effective to detect early stages of the pathology providing complete depiction of the anatomical abnormalities. Secondly infected aortic aneurysm can be successfully treated by antibio-therapy and in situ replacement with cryopreserved arterial homograft.     

Disappearance Of Catecholamine Fluorescence From The Adrenergic Nerves In Arterial Grafts In Rats: An Experimental Fluorescence Histochemical Study

The disappearance of catecholamine fluorescence from the noradrenaline-containing sympathetic nerve fibres after arterial transplantation was studied using a femoral artery graft sutured to rat carotid artery. Glyoxylic acid-induced fluorescence was used to demonstrate adrenergic nerves histochemically. At six hours the network of fibres had started to degenerate, and catecholamine fluorescence from the adrenergic nerves had almost completely disappeared within 24 hours of grafting. Control specimens from normal femoral arteries showed a dense network of fluorescent adrenergic nerves. Based on observations of the relatively rapid liberation of catecholamines from the degenerating adrenergic nerves, we suggest that catecholamines liberated from degenerating adrenergic nerves may have an important role in early vasospasm in microvascular and coronary bypass surgery.     

Femoropopliteal Bypass: In Situ or Reversed Vein Grafts? Ten-Year Results of a Randomized Prospective Study

p < 0.05). Actuarial secondary patency at 10 years was 64.8% in the in situ graft group and 70.2% in the reversed graft group (NS). As a function of vein diameter, actuarial secondary patency at 10 years in the in situ graft group was 37.5% for bypasses using veins with a diameter of 4 mm or less and 80.6% for bypasses using veins larger than 4 mm (p < 0.05). In the reversed graft group the patency rate was 71.2% for bypasses using veins with a diameter of 4 mm or less and 65.5% for bypasses using veins larger than 4 mm. In addition to requiring a training period the in situ technique raises the problem of valve removal especially for small diameter veins. The absence of these disadvantages makes the reversed technique the procedure of choice for femoropopliteal bypass.     

Cryopreserved Arterial Allografts Used for the Treatment of Infected Vascular Grafts

n = 11) or partial removal (n= 7) of infected prosthetic grafts. Revascularizations were aortoaortic (n= 2), aortobifemoral (n= 8), aortounifemoral (n= 3), femorofemoral (n= 2), iliofemoral (n= 1), or femoropopliteal (n= 2) bypasses. Four patients died postoperatively (22%)—one of septic necrosis of the allograft, one of septic rupture of the aortic anastomosis of a previous bypass, one of multiorgan failure, and one of mesenteric infarction. One allograft occluded within 30 days (5.5%), leading to an above-knee amputation. In the remaining patients, routine arteriography or duplex scan showed patent allografts. For the 14 survivors, the mean follow-up period was 20 months (range: 1-45 months). Two patients died—one of septicemia not related to the allograft, and one of multiple organ failure. Among the 12 survivors, 3 patients with non-ABO-compatible allografts developed different types of long-term alterations. One patient had a hemorrhage due to femoral allograft rupture at 45 days, and two patients had aortic allografts dilatation with mural thrombus, necessitating a prosthetic replacement in one patient. Cryopreserved allografts used for the treatment of infected vascular graft are useful in selected cases, although they are not totally resistant to infection. Patients should be followed closely to detect significant long-term alterations of the allografts.     

Revascularization of Left Anterior Descending (LAD) Artery with In Situ Left Internal Thoracic Artery (LITA) and Coronary‐Coronary Free LITA Grafts: 12‐Year Patency

Abstract Background: We aim to present a patient with coronary‐coronary bypass grafting (CCBG), left anterior descending‐left anterior descending (LAD‐LAD) coronary artery bypass with left internal thoracic artery (LITA), and provide the 12‐year follow‐up angiogram to confirm the longest reported patency. Methods and Results: A 57‐year‐old man with three vessel disease where LAD had multiple lesions was operated on. LITA with pedicle was grafted in situ onto the proximal LAD, and the distal residual segment was used as a free LITA graft to bypass the distal stenosis. The postoperative course was uneventful. The patient has been recently readmitted to our clinic with atypical chest pain. In angiography, all of the bypasses, including the free LITA graft, were patent. Conclusions: We used free LITA graft to bypass the distal lesions of LAD in selected patients as a valid alternative to sequential bypass grafting. To the best of our knowledge, this is the only angiographic view of a CCBG in LAD with LITA graft confirming the long‐term patency.     

Harnessing Haemodynamic Forces for the Suppression of Anastomotic Intimal Hyperplasia: the Rationale for Precuffed Grafts

OBJECTIVES: Standardisation of cuff geometry by manufacturing prosthetic precuffed grafts (PCG) theoretically optimises haemodynamic forces. This study was designed in order to determine whether these beneficial flow patterns are replicated in vivo in PCG. PATIENTS AND METHODS: Flow visualisation and Doppler studies performed on anatomically accurate PCG models characterised in vitro anastomotic flow patterns. Thirty-two patients (median age 68 years) in whom autologous vein was unavailable, underwent bypass using PCG. Post-operative analysis included qualitative assessment of flow within the distal anastomosis using Doppler colour flow mapping. Cardiac gating techniques and assessment of velocity distribution were performed to gain additional information. These in vivo results were validated against the bench studies. RESULTS: A cohesive vortex was identified within the distal anastomosis of in vitro models and had an integral relationship with the cardiac cycle. This flow structure was also characterised using Doppler colour flow mapping in both longitudinal and transverse planes, confirming the location of the vortex within the body and proximal part of the anastomosis. Twenty-two patients (69%) undergoing bypass with a PCG underwent successful Doppler assessment one week post-operatively, of whom 17 (77%) had a vortical flow structure identified at the distal anastomosis, similar to that characterised in vitro. Cardiac gating verified the same integral relationship of the vortex with the cardiac cycle as that described in vitro. CONCLUSION: The geometric configuration of precuffed grafts induced vortices within the distal anastomoses in 17 out of 22 patients undergoing arterial reconstruction, thereby harnessing the haemodynamic forces that may suppress anastomotic hyperplasia and improve patency rates.