Bypass Graft Material Research Articles

Multiple Grafting with Single Left Internal Mammary Artery as T-Graft with Itself.

Revascularization strategies might be limited in patients with lack of sufficient bypass graft material and increased risk of wound healing disturbances. In this regard, we present first results of patients treated with left internal mammary artery (LIMA) as T-graft with itself due to left-sided double-vessel disease, elevated risk of wound healing infection, and lack of graft material. Eighteen patients were retrospectively analyzed in this study. All patients received LIMA grafting, and additional T-graft with itself during off-pump coronary artery bypass surgery. The investigation was focused on intraoperative and postoperative outcomes. LIMA-LIMA T-graft was performed in a total of 18 patients. Mean Fowler score accounted for 18.2 ± 2.9. Severe vein varicosis was present in 9 patients, and 38.9% of patients had lacking venous graft material due to prior vein stripping. A total of 2.5 ± 0.5 distal anastomoses were performed. Mean flow of LIMA-left anterior descending anastomosis was 41.72 ± 12.11 mL/min with a mean pulsatility index (PI) of 1.01 ± 0.21. Mean flow of subsequent T-graft accounted for 26.31 ± 4.22 mL/min with a mean PI of 1.59 ± 0.47. Median hospital stay was 7(6.75;8) days. No incidence of postoperative wound healing disorders was observed and all patients were discharged off hospital. LIMA as T-graft with itself to treat left-sided double-vessel disease is feasible and safe in patients with missing bypass graft material and increased risk of deep sternal wound infection. Further prospective studies are necessary to confirm our results.

Remote results of infrainguinal bypass graft procedures for critical lower limb ischaemia

The study was aimed at assessing the remote results of infrainguinal reconstructions in patients with critical lower limb ischaemia depending upon the bypass graft material used. Analysed herein are the results of 237 infrainguinal bypass procedures performed over a 9-year period from January 1st, 2010 to December 31st, 2018. The patients were divided into three groups depending on the level of the distal anastomosis. Each group was then subdivided into subgroups based on the bypass graft material. Group One comprised 40 patients having endured femoral-proximal-popliteal bypass grafting. Group Two was composed of 77 patients after femoral-distal-popliteal bypass graft operations. Group Three included 120 patients after femorotibial bypass graft procedures. The comparative analysis was carried out in the first group between autovenous and synthetic grafts, in the second group - between autovenous, synthetic grafts and xenografts, and in the third group - between autovenous, composite grafts and xenografts. The primary patency rates at 1, 3, and 5 years in the first group amounted to 92, 88, and 73%, in the second group to 68, 60, 45% and in the third group - to 58, 49, and 43%, respectively. The 1-, 3-, and 5-year limb salvage rates in the first group were 100, 100, and 87%, in the second group - 90, 85, 73%; and in the third group - 90, 80, and 79%, respectively. Statistically significant differences were observed only when comparing the femoral-proximal and tibial grafts (p=0.039). Patients' survival at 1, 3, and 5 years in all groups turned out to be approximately similar, amounting in the first group to 92, 84, and 61%, in the second group to 96, 91, 71%, and in the third group to 88, 77, and 69%, respectively (p=0.87). In the first group, there were no significant differences between autovenous and synthetic grafts for any of the parameters studied. In the second group, the synthetic grafts (20%) were significantly inferior by the 5-year patency to autovenous grafts (65%) and xenografts (56%), as well as by the limb salvage rate to autovenous grafts (47 versus 84%). In the third group, the 5-year patency was the worst for the subgroup of composite grafts (15%), with the patency of xenografts being slightly inferior to that of autovenous grafts (33 vs. 55%). In patients presenting with critical ischaemia and requiring infrainguinal bypass grafting, as an alternative to an autovein if unavailable may serve synthetic prostheses when shunting to the proximal portion of the popliteal artery, or xenografts when shunting to the distal portion of the popliteal artery or tibial arteries. Despite worse patency, with their help it is possible to achieve regression of critical ischaemia and an acceptable limb salvage rate, which is comparable to the results of autovenous grafts.

SFRR-E Young Investigator Awardee P40 - The skin autofluorescence reflects the posttranslational glycation grade of the matrix protein collagen

Advanced glycation end products (AGEs) seem to be involved in ageing as well as in the development of cardiovascular diseases. Accumulation of AGEs contribute to tissue stiffness and organ dysfunction by crosslinking extracellular matrix proteins like collagen. We aimed to assess whether AGE-modified cardiac tissue collagen and AGE related skin autofluorescence may reflect the cardiac function and have a prognostic value for the outcome of coronary artery bypass surgery patients. Therefore, AGE-modifications in collagen from 72 male patients undergoing isolated coronary artery bypass graft (CABG) surgery were analyzed. Collagen fractions were isolated from the right atrial auricle and the residual bypass graft material (saphenous vein) of these patients and quantified by 4-hydroxyproline assay. AGE modifications were determined by the AGE intrinsic fluorescence (excitation 360nm/emission 440nm). The skin autofluorescence (sAF) as a non-invasive parameter was measured using the AGE reader. The non-extractable collagen contained the highest amounts of AGEs and positively correlates with the patients age (p=0.0001), blood glucose level (p=0.002), HbA1c level (p=0.01) and sAF (p=0.008). The right atrial auricle collagen showed significantly more modifications compared to vein graft material of the same patient (p=0,001). Skin autofluorescence positively correlates with AGE content in cardiac tissue (p=0.01) and therefore could be used as a predictor of tissue stiffness in patients with coronary heart disease.

Midcab-facilitates-combined-curative-treatment-in-the-high-risk-patient.pdf

Objective: Report of a high risk patient undergoing combined treatment of orthopedic and cardiovascular operations enabling a succesful outcome through a minimally invasive approach. Methods: We report the clinical presentation, medical record, strategies for decision finding and clinical images of a perioperative cardiac infarction during infectious complicated orthopedic re-do surgical treatment that was managed succesfully in a 72 –year –old female high risk patient via minimally invasive direct coronary artery bypass grafting Results: Minimally invasive direct coronary artery bypass grafting represents an excellent revascularization option for patients who are at high risk for sternotomy and cardiopulmonary bypass related complications.This approach enabled the necessary following orthopedic operations and early mobilization of the obese patient resulting in weight loss, enchanced pulmonary function and cure of the infected focus. The minimal invasive coronary artery bypass grafting technique prevented sternal bone instability, infection and facilitated the use of physiotherapy and walking sticks after the orthopedic operation to replace an infected knee prosthesis.The patient could be discharged and presented during follow up in healthy condition with a decrease in body mass index and ability to be fully mobilized. Conclusions: Minimally invasive direct coronary artery bypass grafting represents an excellent revascularization option for patients who are at high risk for sternotomy and cardiopulmonary bypass related complications. Especially patients who suffer from perioperative cardiac infarction who need urgent treatment are suitable for this approach as the internal mamarian artery is used as a graft and no additional bypass graft material is needed. Most patients undergoing revascularization lack of suitable bypass material or require pre-operative evaluations of their vein material. Minimally invasive direct coronary artery bypass grafting shows superior results in the long time follow up when compared to angioplasty and stenting.

Single-Center Experience in Endovascular Treatment for Infrainguinal Bypass Obstructions

PurposeTo evaluate patency and clinical efficacy of endovascular therapy for infrainguinal bypass obstructions. Materials and MethodsPatients were categorized with regard to symptoms (asymptomatic/intermittent claudication [IC] vs critical limb ischemia [CLI]), bypass graft material used (autologous vs prosthetic graft), and localization of distal anastomoses (femoropopliteal vs femorodistal bypass). Primary patency was defined as absence of sonographically verified stenosis greater than 50%. Assisted primary patency was applied to secondary revisions to prevent impending occlusion. Secondary patency refers to repeat interventions aimed at restoring bypass patency after occlusion. Primary sustained clinical improvement in IC was defined as an upward shift of at least one category per Rutherford classification, accordingly to a level of claudication in patients with CLI. ResultsA total of 54 patients (54 limbs, 12 with CLI) were included. At 1 year, primary patency rates were 74% in IC and 27% in CLI (P = .001), primary assisted patency rates were 85% in IC and 68% in CLI (P = .05), and secondary patency rates were 89% in IC and 100% in CLI (P = .32). Accordingly, primary sustained clinical improvement rates were 64% in IC and 25% in CLI (P = .018). After adjustment for confounding factors, CLI (hazard ratio [HR], 7.8; 95% CI, 2.3–26.32; P = .001) and impaired patent runoff (ie, less than three crural runoff vessels; HR, 0.16; 95% CI, 0.03–0.96; P = .045) were independently associated with impaired primary patency. ConclusionsEndovascular revascularization is a reasonable treatment option to prevent impending bypass occlusion. Presence of CLI and impaired crural runoff are independent risk factors for lower patency rates.

Advanced glycation end product associated skin autofluorescence: A mirror of vascular function?

Advanced glycation end products (AGEs) seem to be involved in aging as well as in the development of cardiovascular diseases. During aging, AGEs accumulate in extracellular matrix proteins like collagen and contribute to vessel stiffness. Whether non-invasive measurement of AGE accumulation in the skin may reflect vessel function and vessel protein modification is unknown. Herein we set out to analyze the AGE-modifications in the collagens extracted from residual bypass graft material, the skin autofluorescence reflecting the accumulation of AGEs in the body as well as the pulse wave velocity reflecting vessel stiffness.Collagen types I and III (pepsin digestible collagen fraction) were isolated from the veins of 52 patients by proteolysis. The residual collagen fraction was further extracted by collagenase digestion. Collagen was quantified by hydroxyproline assay and AGEs by the AGE intrinsic fluorescence. Skin autofluorescence was measured with an autofluorescence reader; pulse wave velocity with the VICORDER®.The collagen AGE autofluorescence in patient vein graft material increased with patient age. The pepsin digestible collagen fraction was significantly less modified in comparison to the collagenase digestible fraction. Decreasing amounts of extracted collagenase digestible collagen correspond with increasing AGE autofluorescence. Skin autofluorescence and vessel stiffness were significantly linked to the AGE autofluorescence of the collagenase digestible collagen fraction from graft material. In conclusion we have found that skin autofluorescence and pulse wave velocity as non-invasive parameters significantly correlate with the AGE contained in graft material and therefore are strong predictors of vessel AGE modifications in patients with coronary heart disease. Whether the analysis of the skin autofluorescence leads to an improvement of the risk stratification in patients suffering from cardiovascular disease has to be further tested.

Analysis of advanced glycation end product modifications in collagen of cardiac tissue and graft material from patients suffering from coronary heart disease

Background: Advanced glycation end products (AGEs) seem to be involved in ageing as well as in the development of cardiovascular diseases. During ageing, the AGEs accumulate in matrix proteins like collagen and fibronectin inducing tissue stiffness. The Bypass operation is the most common intervention in patients suffering from coronary heart disease. However as the majority of the patients are older than 60, the graft material (vein or artery) of these patients is probably enriched on AGE-modifications. To which extent these modifications may affect the quality and functionality of bypass graft material and the heart function after operation is unknown. We analyzed the AGE-modifications in the collagen from the right atrium and residual bypass graft material (saphenous vein and internal thoracic artery) to elucidate in which extension the collagen of graft material is AGE-modified. Methods: Collagen type I and III (soluble fraction) were isolated from veins, arteries and the right atrium by proteolysis with pepsin. The residual insoluble fraction was extracted by digestion with collagenase type I and proteinase K. Collagen was quantified by 4-hydroxyproline assay and AGEs by the AGE intrinsic fluorescence (360nm excitation and 440nm emission). Results: The AGE fluorescence in patient material (vein, atrium) increased with patients age (p=0.0025). Decreasing amounts of extracted insoluble collagen correlate with increased AGE fluorescence (p=0.0001). Comparing vein, artery and atrium of the same patients we isolated equal levels of soluble and insoluble collagen in arteries and atriums, whereas only in veins increased amounts of soluble collagen were extracted in comparison to the insoluble fraction (p<0.05). The soluble fraction in every tissue was significantly less modified in comparison to the insoluble collagen (p<0.05). Conclusion: Ageing is reflected by an increase in AGE related tissue collagen fluorescence. Increase crosslinking of collagen, reflected by high AGE fluorescence, may be the cause of reduced amounts of insoluble extracted collagen. High levels of AGE-modifications are known to block the proteolytic degradation by matrix metalloproteinase. Arteries and cardiac tissue (right atrium) showed significantly more modifications compared to vein graft material of the same patients. Our results may indicate why veins and arteries behave differently as bypass graft material. This will be further evaluated from our group.

Femoro-Popliteal Bypass Above Knee with Saphenous Vein vs Synthetic Graft

There is still debate whether sintethic graft (polytetrafluoroethylene or Dacron) is equivalent to vein as bypass graft material for the above-knee femoropopliteal bypass. Therefore, we performed prospective randomized trial to compare vein with polytetrafluoroethylene/dacron for femoropopliteal bypasses with the distal anastomosis above the knee. Between January 2000 and June 2003, 121 femoropopliteal bypasses were performed. The indications for operation were severe claudication in 96 cases, rest pain in 16 cases, and ulceration in 9 cases. After randomization, 60 reversed saphenous venous bypasses and 61 polytetrafluoroethylene/dacron bypasses were performed. No perioperative mortality was seen, and 5% of the patients had minor infections of the wound, not resulting in loss of the bypass, the limb, or life. After 5 years, 37% of the patients had died and 7% were lost to follow-up. Only once saphenous vein was necessary for coronary artery bypass grafting. Primary patency rates after 5 years were 76,6% for venous bypass grafts and 59,1% for polytetrafluoroethylene/dacron grafts (p=0,035). Secondary patency rates were 83,3% for vein and 69,2% for polytetrafluoroethylene/dacron bypasses (p = 0,036). In the venous group, 10 bypasses failed, leading to four new bypasses. In the polytetrafluoroethylene group, 22 bypasses failed, leading to 12 reinterventions. After 5 years of follow-up, we conclude that a bypass with saphenous vein has better patency rates at all intervals and needs fewer reoperations. Saphenous vein should be the graft material of choice for above-knee femoropopliteal bypasses and should not be preserved for reinterventions. Polytetrafluoroethylene/dacron is an acceptable alternative if the saphenous vein is not available.

Transbrachial thrombolysis, PTA and stenting in the lower extremities.

We present an analysis of 37 interventions in the arteries of the lower limbs via a transbrachial arterial approach. Twenty-six patients (42-79 years) underwent 37 interventional procedures in the lower extremities (iliac n = 6, iliac + femoro-popliteal n = 1, femoro-popliteal n = 30) with a vascular approach via the brachial artery (33 left sided, 4 right sided, introducer sheath 4-7 F). The transbrachial approach was chosen to avoid puncture of femoral bypass graft material. Technical success could be achieved in 11/13 thrombolyses, 8/9 PTAs, 7/10 combinations of thrombolysis and percutaneous transluminar angioplasty (PTA) and in the placement of two stents. One patient suffered from periprocedural severe re-thrombosis due to insufficient anticoagulation during fibrinolysis, and twice thrombolysis was incomplete. One puncture-related false aneurysm of the brachial artery had to be corrected surgically. One transient ischemic attack (TIA) and four minor complications occurred. Transbrachial vascular approach for arterial interventions in iliac and femoro-popliteal pathologies is a reasonable alternative to the transaxillary access if transfemoral puncture has to be avoided. The technical success rate is comparable with the results of the transaxillary and transfemoral approach. To minimize, at least theoretically, the risk of cerebral complications, the left-sided approach should be preferred and intravenous heparin should be administered routinely.

Prospective randomized study on bilateral above-knee femoropopliteal revascularization: polytetrafluoroethylene graft versus reversed saphenous vein

Some controversy exists as to whether polytetrafluoroethylene (PTFE) is equivalent to reversed saphenous vein (SV) as bypass graft material for above-knee femoropopliteal revascularization. We compared the 5-year patency rate with reversed SV and PTFE grafts in patients with claudication who underwent bilateral above-knee femoropopliteal revascularization. Between January 1994 and December 1997, 51 patients (102 limbs) with bilateral disabling claudication due to superficial femoral artery occlusion underwent above-knee femoropopliteal bypass grafting, with SV in one limb and PTFE graft in the other limb. Patients were randomly selected for sequential surgical treatment with either SV-PTFE or PTFE-SV. Kaplan-Meier analysis was used to estimate patency rate, and various factors were analyzed to ascertain any association with revascularization failure. There was no perioperative (30 day) limb loss or death, but five late deaths (late survival rate, 90%). Mean follow-up was 59 months. In the SV group, three bypass grafts failed, requiring repeat operation in only one patient. In the PTFE group, eight bypass grafts failed, leading to five repeat operations. There was no statistically significant difference in primary "assisted" patency rate for the two grafts: 100%, 98%, and 94% for SV grafts, and 96%, 84%, and 84% for PTFE grafts (P =.09), after 1, 3, and 5 years, respectively. The overall results of this randomized study show that SV and PTFE grafts have a statistically comparable patency rate when used above the knee in patients with claudication. Use of SV, however, leads to fewer occlusions and repeat operations.

Remodeling and suppression of intimal hyperplasia of vascular grafts with a distal arteriovenous fistula in a rat model

Purpose: The purpose of this study was to evaluate the effects of a distal arteriovenous fistula (dAVF) on the morphologic changes occurring in arterial bypass grafts by the use of a novel experimental model. Methods: Aortofemoral bypass grafts with or without dAVFs were constructed in 36 Sprague-Dawley rats with a microsurgical technique. The bypass graft material consisted of deendothelialized autogenous tail artery (length, 25 mm; inside diameter, 0.5 mm). In 18 rats, dAVFs were constructed at the distal anastomosis. After 6 weeks, flow rates and shear stress were determined, and grafts were then harvested. Luminal, intimal, and medial cross-sectional areas were measured with computer imaging. Desmin, α–smooth muscle actin, and von Willebrand factor (vWF) were identified with immunohistochemistry. Endothelialization was evaluated with SEM. Results: All bypass grafts remained patent at the time of graft harvest. Grafts with dAVFs showed increased flow rates (11.5 ± 0.6 mL/min) compared with grafts without dAVFs (2.1 ± 0.3 mL/min; P <.01). Shear stress was also increased in the dAVF group (340.9 ± 23.4 dyne/cm2 vs 113.7 ± 12.5 dyne/cm2; P <.01), with a corresponding suppression of intimal hyperplasia (0.059 ± 0.011 mm2 for dAVF grafts vs 0.225 ± 0.009 mm2 for non-dAVF grafts; P <.01). Staining for vWF was found in both the reendothelialized flow surface and the neointimal extracellular matrix. Remodeling of the grafts was characterized by a 50% increased luminal area, 70% decreased intimal area, and a 25% decreased medial area when a dAVF was constructed. Conclusion: A small animal experimental model of an arterial bypass graft can enable the evaluation of a variety of factors that influence graft patency. Increased blood flow velocity and shear stress induced by a dAVF are associated with a decrease in intimal and medial areas, which may reflect changes in cell proliferation, apoptosis, migration, or matrix deposition. Deposition of vWF was also found both in the endothelium and throughout the hyperplastic intima. These findings suggest that the hemodynamic and morphologic changes associated with dAVF may potentiate graft patency and function. (J Vasc Surg 2001;34:701-6.)