Natural remodeling of the distal anastomosis of an above-knee femoropopliteal bypass depicted by CT angiography of lower limbs improves geometry of the reconstruction.

The geometry of the distal anastomosis of a femoropopliteal bypass influences local hemodynamics and formation of intimal hyperplasia. We hypothesized that the distal anastomosis of an above-knee femoropopliteal bypass undergoes remodeling that results in displacement of the original course of the popliteal artery and change in the anastomosis angle. We identified 43 CT angiography examination with proximal femoropopliteal bypass and either a preserved contralateral popliteal artery or previous CTA before construction of the bypass for comparison. In these examinations, we measured the displacement distance and angle at the level of the distal anastomosis and compared these measurements with clinical and imaging data. The displacement distance was 8.8+/-4.9 mm (P<0.0001) and the displacement angle was -1° (IQR=44°). The angle between the inflow and outflow artery was 153+/-16° (P<0.0001). There was a negative association between the displacement angle and the angle between the bypass and the outflow artery (r=-0.318, P=0.037). Patients with reversed venous grafts had a greater displacement of the anastomosis (14.7+/-3.0 mm) than patients with prosthetic grafts (8.0+/-4.5 mm, P=0.0011). We conclude that construction of a distal anastomosis of proximal femoropopliteal bypass results in displacement of the original course of the popliteal artery towards the bypass and this effect is more pronounced in reversed venous grafts.

Branched pedal bypass in the treatment of critical limb ischemia - a single center experience.

INTRODUCTION: Pedal bypass is a therapeutic option for limb salvage in critical limb ischemia. METHOD: Retrospective analysis of 20 patients who underwent either simple (14 patients) or branched (6 patients) pedal bypass in a single center and had at least one postoperative follow-up. In patients with branched pedal bypass, the main trunk was connected to the pedal artery of better quality and the side branch to an artery on the opposite side of the foot. The main trunk was constructed as a reverse saphenous bypass in all patients with branched bypass. From patients with simple bypass, nine had reverse saphenous graft, three had an allograft, one patient had in situ saphenous graft, and one PTFE prosthesis. RESULTS: The difference in the operation time was not significant. One patient with simple bypass required reoperation for wound bleeding and there was one case of perioperative mortality in the same group. The difference between the groups in the primary or secondary patency rates, limb salvage and overall survival was not significant. CONCLUSIONS: We did not find any significant difference in patency rates, limb salvage, or perioperative complications between patients with simple and branched pedal bypass in our cohort. We believe that the anticipated benefits of constructing an additional branch are masked by the disadvantageous presence of an additional anastomosis. Adoption of a branched pedal bypass may therefore require further improvements - perhaps the utilization of a branched saphenous graft. Key words:  critical limb ischemia - peripheral arterial disease - bypass - revascularization - amputation.

Dunbar syndrome - single-center experience with surgical treatment.

INTRODUCTION: Dunbar syndrome is caused by compression of the truncus coeliacus (TC), most commonly by the median arcuate ligament. Chronic irritation of the TC during breathing leads to fibrous changes of the arterial wall and formation of fixed stenosis. This compression syndrome is often associated with specific complaints including weight loss and early postprandial epigastric pain. In this study, we summarize our experience with a group of 14 patients from a single institution. METHODS: In 14 patients who were diagnosed with Dunbar syndrome and who were referred for surgery, we performed an invasive measurement of systemic pressure in a. radialis during the operation and compared it with invasively measured pressure in a. gastrica sinistra before and after the release of TC. In patients with significant stenosis (pressure gradient above 15 mmHg), a bypass was performed. RESULTS: The initial pressure gradient of 56±19 mmHg decreased after the release of TC to 39±16 mmHg (p.

The ratio of diameters between the target artery and the bypass modifies hemodynamic parameters related to intimal hyperplasia in the distal end-to-side anastomosis.

Hemodynamics in the distal end-to-side anastomosis is related to early development of intimal hyperplasia and bypass failure. In this study we investigated the effect of diameter ratios between the target artery and the bypass at three different angles of the connection. The pulsatile flow field was visualized using particle image velocimetry in transparent models with three different angles of the connection (25°, 45°, 60°) and the diameter ratio between the bypass and the target artery was 4.6 mm : 6 mm, 6 mm : 6 mm, and 7.5 mm : 6 mm. Six parameters including location and oscillation of the stagnation point, local energy dissipation, wall shear stress (WSS), oscillatory shear index, spatial and temporal gradient of WSS and their distribution in the target artery were calculated from the flow field. In the wider bypass, the stagnation point oscillated in a greater range and was located more proximal to the anastomosis. Energy dissipation was minimal in a wider bypass with a more acute angle. The maximum WSS values were tree times greater in a narrow bypass and concentrated in a smaller circular region at the floor of the anastomosis. The oscillatory shear index increased with wider bypass and more acute angle. The maximum of spatial gradient of WSS concentrated around the floor and toe of the anastomosis and decreased with more acute angle and wider bypass, the temporal gradient of WSS was stretched more towards the side wall. Greater bypass to target vessel ratio and more acute anastomosis angle promote hemodynamics known to reduce formation of intimal hyperplasia.

The influence of the anastomosis angle on the hemodynamics in the distal anastomosis in the infrainguinal bypass: an in vitro study.

The geometric shape of the distal anastomosis in an infrainguinal bypass has an influence on its durability. In this article, we compared three different angles of the anastomosis with regard to the hemodynamics. Three experimental models of the distal infrainguinal anastomosis with angles of 25°, 45°, and 60° respectively were constructed according to the similarity theory to assess flow in the anastomoses using particle image velocimetry and computational fluid dynamics. In the toe, heel, and floor of the anastomosis that correspond to the locations worst affected by intimal hyperplasia, adverse blood flow and wall shear stress were observed in the 45° and 60° models. In the 25° model, laminar blood flow was apparent more peripherally from the anastomosis. In conclusions, decreasing the distal anastomosis angle in a femoropopliteal bypass results in more favorable hemodynamics including the flow pattern and wall shear stress in locations susceptible to intimal hyperplasia.

Gastrointestinal complications after cardiac surgery : eight years experience in a single center.

BACKGROUND: The aim of this study was to evaluate the frequency of gastrointestinal complications (GICs) and associated risk factors in patients after cardiac surgery, and to stratify them according to the risk of developing GICs in order to improve our diagnostic protocols. METHODS: A total of 5959 patients who underwent cardiac surgery within a period of 97 months were retrospectively evaluated. Surgical procedures included coronary artery bypass grafting, heart valve surgery, aortic surgery, surgical correction of adult congenital heart defects, or combined procedures. RESULTS: The frequency of GICs was 1.3% (75 patients). Intestinal ischemia and upper or lower gastrointestinal bleeding were the most common GICs. From 27 patients affected by intestinal ischemia, 21 patients were previously treated with intra-aortic balloon pump (p < 0.001). Low cardiac output, renal failure or dysfunction, renal risk, peripheral arterial disease, history of myocardial infarction, male gender, intra-aortic balloon pump, cardiopulmonary bypass time, aortic cross-clamp time, duration of intubation, SIRS, and MODS were associated with significantly increased risk of GICs. CONCLUSIONS: To decrease the occurrence of intestinal ischemia, we suggest that placement of intra-aortic balloon pump should be preceded by examination of the descending aorta to rule out severe atherosclerotic changes, in which case -alternative cardiac support should be attempted.

Endoscopic versus mini-invasive radial artery graft harvesting for purposes of aortocoronary bypass.

The aim of the study was to compare three different methods of radial artery harvesting with regard to postoperative complications and perioperative stress of the patient. A total of 60 patients admitted for coronary artery bypass surgery were randomized into three groups. Each patient underwent extraction of radial artery, all performed by a single surgeon. The radial artery was harvested by one of the following three techniques: classical technique (20 patients), mini-invasive technique (20), and endoscopic technique (20). The time required for the graft harvest was greater in the group where the endoscopic technique was used (52.6 ± 11.3 min) than with the mini-invasive (41.5 ± 7.3 min) or the classical (27.8 ± 4.6 min) technique. Postoperative blood loss into drains was higher where the classical technique was used (35.5 ± 9.4 ml) as compared to the mini-invasive (20 ± 5 ml) or the endoscopic (10 ± 7.3 ml) technique. There was no significant difference among the groups in the rate of local neurological complications, contusion of wound edge, edema of the extremity, or wound infection rate. We observed no case of ischemia of the extremity, and a single case of postoperative myocardial ischemia in the group where the classical technique was used. From a clinical point of view, the mini-invasive and the endoscopic approach are comparable, but the latter is more expensive. Both mini-invasive and endoscopic techniques prolong the operation, reduce perioperative blood loss, and require additional training time.

The anastomosis angle is a key to improved long-term patency of proximal femoropopliteal bypass.

BACKGROUND: Femoropopliteal bypass is a common vascular reconstructive procedure. A significant proportion of bypasses become ineffective within 1 year because of occlusion due to progression of intimal hyperplasia (IH). METHODS: The clinical part of the study involved an analysis of 43 patients with proximal femoropopliteal bypass, which became occluded no later than 1 year from the procedure, who were successfully treated with thrombolysis. Morphological changes of intima in the anastomosis (evaluated angiographically) and the angle of the distal end-to-side anastomosis were evaluated. In the second part of the study, blood flow in the distal end-to-side anastomosis was modeled experimentally (by particle image velocimetry) and numerically (by computational fluid dynamics). The results were correlated with the previously identified locations of IH. RESULTS: We proved that the locations of IH correlate with the locations of disturbed blood flow, increased wall shear stress, and stagnation points as documented by experimental visualization and angiographic findings. We also confirmed that anastomoses with more acute angles are less prone to IH and occlusion of the lumen. CONCLUSION: We suggest that a better understanding of the hemodynamics and its influence on IH should lead to an optimized graft design by adopting a more acute angle of the anastomosis.