The Diagnosis and Treatment of Arterial Injuries

Repair of arterial injuries has decreased the amputation rate to 15% from 50%, which was prevalent when ligation was practised. Methods of treatment include lateral repair, resection of damaged area with end-to-end anastomosis, and resection and graft, with or without the assistance of partial or complete cardiopulmonary bypass. Lacerations of large arteries (aorta, iliac) may be treated by lateral repair. Lacerations of smaller arteries are best treated by resection and anastomosis, or by resection and graft. True and false aneurysms and arteriovenous fistulas are best treated by resection and restoration of blood flow. “Spasm” in an artery is frequently due to intimal rupture or subintimal hemorrhage, and likewise requires resection and anastomosis in many instances. Clinical examples of each type of injury are presented. Angiography is of great value in establishing the precise abnormality present, its location, the degree of collateral circulation, and the result achieved by surgery.     

Comparative study of flow in right-sided and left-sided aortas: numerical simulations in patient-based models

A right-sided aorta is a rare malformation which may be associated with other various types of congenital heart disease. We utilised haemodynamic, echocardiographic measurements, computerised tomography and image reconstruction software packages that were integrated in a computational fluid dynamics model to determine blood flow patterns in patient-based aortas. In the left-sided aorta, a systolic clockwise rotational component was present, while helical flow was depicted in the aortic arch that was converted in the descending aorta as counter-rotating vortices with accompanying retrograde flow. The right-sided configuration has not altered the orientation of the three-dimensional vortex, but intensification of polymorphic flow patterns, alterations in wall shear stress distribution and development of a lateral pressure gradient at the area of an aneurysmal anomaly was observed. Moreover, increments of Reynolds, Womersley and Dean numbers were evident. These phenomena along with the formation of the aneurysm might influence cardiovascular risk in patients with right-sided aortas.     

Effects of aortic irregularities on blood flow

Anatomic aortic anomalies are seen in many medical conditions and are known to cause disturbances in blood flow. Turner syndrome (TS) is a genetic disorder occurring only in females where cardiovascular anomalies, particularly of the aorta, are frequently encountered. In this study, numerical simulations are applied to investigate the flow characteristics in four TS patient- related aortic arches (a normal geometry, dilatation, coarctation and elongation of the transverse aorta). The Quemada viscosity model was applied to account for the non-Newtonian behavior of blood. The blood is treated as a mixture consisting of water and red blood cells (RBC) where the RBCs are modeled as a convected scalar. The results show clear geometry effects where the flow structures and RBC distribution are significantly different between the aortas. Transitional flow is observed as a jet is formed due to a constriction in the descending aorta for the coarctation case. RBC dilution is found to vary between the aortas, influencing the WSS. Moreover, the local variations in RBC volume fraction may induce large viscosity variations, stressing the importance of accounting for the non-Newtonian effects.     

Surgical technique in the rat model of kidney transplantation

Today successful kidney transplantation procedures, techniques and immunosuppression protocols are a consequence of extensive research on animal models. During every transplantation surgery there are two crucial points for the success of the entire procedure: vascular (arterial end venous) and ureteral or ureterovesical anastomosis. Renal artery and vein of the donor kidney can be anastomosed end-to-side to the abdominal aorta and vena cava of the recipient (heterotopic transplantation), or end-to-end to the remains of renal artery and vain of the recipient (orthotopic transplantation) after nephrectomy. The ureter can be anastomosed also end-to-end or we can connect it directly to the urinary bladder (ureterocystoneostomy). The aim of this study was to elucidate which technique has better results according to: animal survival, reperfusion and perfusion of the transplanted kidney, elimination of the urine from the transplanted kidney and procedure costs. The study included 240 (120 donors and 120 recipients) male Wistar rats (3 months old; weight 250-300 g Our results are clearly showing that the end-to-end vascular anastomosis, and Paquins ureterovesical anastomosis have better results in transplanted rat kidneys survival and urine drainage compared to end-to-side vascular anastomosis and end-to-end ureteral anastomosis. Based on our experience we can conclude that described methods of end-to-end vascular anastomosis and Paquins ureterovesical anastomosis are less technically demanding and have a shorter learning curve. Therefore, we can recommend the use of described methods in kidney transplantation related researches.     

Murine Kidney Transplant Technique

The first mouse kidney transplant technique was published in 1973¹ by the Russell laboratory. Although it took some years for other labs to become proficient in and utilize this technique, it is now widely used by many laboratories around the world. A significant refinement to the original technique using the donor aorta to form the arterial anastomosis instead of the renal artery was developed and reported in 1993 by Kalina and Mottram ² with a further advancement coming from the same laboratory in 1999 ³. While one can become proficient in this model, a search of the literature reveals that many labs still experience a high proportion of graft loss due to arterial thrombosis. We describe here a technique that was devised in our laboratory that vastly reduces the arterial thrombus reported by others ^4,5. This is achieved by forming a heel-and-toe cuff of the donor infra-renal aorta that facilitates a larger anastomosis and straighter blood flow into the kidney.     

The calibre of the Foramen of Panizza in Crocodylus porosus is variable and under adrenergic control

The foramen of Panizza is located within the outflow tract of the crocodilian heart, between the left and right aortas. It has been suggested that the foramen of Panizza has a variable calibre, which could explain the profound changes in the distribution of flows and pressure profiles recorded in the right and left aortas. We investigated this possibility using a modified in-situ perfused heart preparation in combination with isolated strip preparations from the outflow tract. In the perfused heart preparation, bolus injections of adrenaline increased the resistance in the foramen of Panizza, indicating a decrease in its diameter. Isolated strip preparations from the outflow tract showed a concentration-dependent increase in tension in response to adrenaline, while vasoactive intestinal polypeptide caused a relaxation in adrenaline pre-contracted strip preparations. We propose that an increase in the diameter of the foramen of Panizza may be important during pulmonary to systemic shunts to allow blood to flow from the left to right aorta (reverse foramen flow) in order to supply the carotid and coronary arteries. During non-shunting conditions, a constricted foramen may prevent excess flow from the right to left aorta during diastole.     

Comparison of vascular hemodynamics in experimental models of microvascular anastomoses

Blood flow was measured in the canine saphenous artery using electromagnetic flowmetry. Significant increase in blood flow was noted after occlusion of the distal femoral artery. However, after raising a saphenous island flap there was no significant change in the blood flow before and after distal femoral artery occlusion. The flap peripheral resistance and blood flow were compared after end-to-end and end-to-side anastomosis and no statistical difference was noted.     

Variable Pringle Maneuvers and Effect on Intestinal Epithelium in Rats. A Pilot Experimental Study in Rats

Background

It is observed that combined liver and colon surgery especially when this includes major liver resection with Pringle maneuver (PM) performance does not have a favorable outcome. Aim of our experimental study is to investigate the impact of portal triad occlusion on the large bowel and intra-abdominal inflammation and potent protective effects of the variants of (PM) in the combined surgical cases.

Materials and Methods

Forty-four rats were divided into four groups. In group A (control group), 1cm of the left partial colon was resected and then an end-to-end anastomosis was performed. In group B, a continuous PM for 30 minutes was performed followed by resection of 1cm of the left colon and an end-to-end anastomosis. In group C, the left colonic resection and anastomosis was performed after intermittent PM (IPM), which was 10 minutes PM followed by 5 minutes reperfusion repeated for three circles. In group D, an ischemic preconditioning for 10 minutes was initially performed followed by 5 minutes reperfusion and then continuous PM for 30 minutes. Finally the rats in group D underwent a 1cm left colonic resection and an end-to-end anastomosis.

Results

The percentage of colitis was higher in the B group (P = 0,19). The percentage of inflammation was not significantly higher even when we compared all “occlusion” groups (B+C+D) with the sham group. No evidence of pancreatitis was found in the sham group whereas amylase and lipase levels were higher in Groups B, C and D together (P = 0,0267). The comparison of group A to group B showed a significant difference (P = 0,0014) caused by continuous PM for 30 minutes, but there was no such result after IPM.

Conclusions

Major liver resections are performed with PM in order to minimize intra-operative blood loss. In the combined cases of colon surgery and major liver resections where PM is needed our results showed that IPM presents with better outcome and could be preferred compared with the other PM variants.     

Vascular anastomosis using controlled phase transitions in poloxamer gels

Vascular anastomosis is the cornerstone of vascular, cardiovascular and transplant surgery. Most anastomoses are performed with sutures, which are technically challenging and can lead to failure from intimal hyperplasia and foreign body reaction. Numerous alternatives to sutures have been proposed, but none has proven superior, particularly in small or atherosclerotic vessels. We have developed a new method of sutureless and atraumatic vascular anastomosis that uses US Food and Drug Administration (FDA)-approved thermoreversible tri-block polymers to temporarily maintain an open lumen for precise approximation with commercially available glues. We performed end-to-end anastomoses five times more rapidly than we performed hand-sewn controls, and vessels that were too small (<1.0 mm) to sew were successfully reconstructed with this sutureless approach. Imaging of reconstructed rat aorta confirmed equivalent patency, flow and burst strength, and histological analysis demonstrated decreased inflammation and fibrosis at up to 2 years after the procedure. This new technology has potential for improving efficiency and outcomes in the surgical treatment of cardiovascular disease.     

食蟹猴肾移植模型的建立

目的建立食蟹猴的肾移植模型。方法通过显微外科手术对食蟹猴进行同种异体移植,将供体肾动脉、肾静脉分别端侧吻合到受体腹主动脉、下腔静脉,供体输尿管端端吻合到受体输尿管。结果154例肾移植食蟹猴无一只在手术过程中因意外死亡;无一只因手术感染死亡;无一只因手术并发症死亡;肾热缺血时间（30±4.5）min。结论应用食蟹猴建立肾移植模型,技术成熟,方法可靠。应用此模型评价新型免疫抑制药物,进行免疫耐受、异种移植研究可为临床试验提供更为准确可靠的依据。     

Numerical simulation of haemodynamics of the descending aorta in the non-diabetic and diabetic rabbits

Diabetes mellitus (DM) is a predisposing risk factor leading to macrovascular diseases. Changes in haemodynamics of the diabetic aortas remain largely unclear and relevant computational analyses are lacking in the literature. Ten adult rabbits (1.6–2.2 kg) were collected and the type I diabetic rabbit model was induced by injection of alloxan. A total of five control and five diabetic rabbit aortas were considered for subsequent numerical simulation. The CT scanning was performed to reconstruct three-dimensional model of the individual rabbit descending aorta. The flow velocity waveforms were measured by ultrasound machine and were set to be the inlet boundary conditions. The reconstructed aortas were then imported into ANSYS to perform mesh generation and computational analysis. Results showed that the distributions of haemodynamic indicators time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and transverse wall shear stress (transWSS) in the non-diabetic rabbit aortas were similar to those in the diabetic rabbit aortas. However, the mean values of TAWSS and transWSS in the non-diabetic rabbit aortas were significantly higher than those values in the diabetic rabbit aortas (TAWSS: p = 0.04; transWSS: p = 0.02). The back of right renal artery tended to have high OSI in both the non-diabetic and the diabetic rabbit aortas. Notably, the regions with high OSI tended to have intense disturbed flow and low TAWSS in the most diabetic rabbit aortas. The results suggest that diabetes leads to changes in haemodynamic parameters in the rabbit aortas. In particular, the lower TAWSS and the higher OSI within the diabetic aortas may further contribute to aortic wall remodeling.     

Limitations of Doppler echocardiography for the post-operative evaluation of aortic coarctation.

Doppler blood flow measurements and derived pressure differences, through the Bernoulli equation, are used in the diagnosis of aortic coarctation, a congenital stenosis distal to the left subclavian artery. Doppler velocities remain elevated at the coarctation site after successful repair of coarctation, leading to high Doppler derived pressure differences without significant arm-leg pressure differences. We studied this apparent contradiction of two diagnostic methods, in vivo using patient and control data, and in vitro using a hydraulic model. Clinical and echocardiographic data from 31 patients, aged 13.0 +/- 4.0, 10.5 +/- 4.7 yr after coarctectomy by end-to-end anastomosis, and 18 age-matched healthy subjects were reviewed. Doppler peak velocities at the aortic isthmus were elevated in patients (2.2 +/- 0.4 vs. 1.2 +/- 0.2m/s, P < 0.001), corresponding to significant Doppler differences (20 +/- 7 mmHg), however, without significant arm-leg pressure differences. In all patients, a mild anatomic stenosis could still be observed. Local stiffness was increased. The hypothesis that the less distensible surgical scar in post-coarctectomy patients leads to a significant dynamic obstruction in systole was validated in a latex model of the aorta. Rigid rings (0.5-1.5 cm), matching the unloaded aortic diameter, were mounted around the aorta. Under loading conditions, Doppler peak velocities increased by 40 +/-7%, yielding Doppler differences of 21 +/- 3 mmHg, without a significant pressure drop. An alternative expression to calculate pressure differences, using both velocity and geometric information, was validated in the model. In conclusion, post-operatively, Doppler velocities remain elevated due to a mild anatomical and significant dynamic narrowing, but the specific geometry, resembling a tubular hypoplasia rather than an abrupt stenosis, permits an almost complete pressure recovery explaining the occurrence of Doppler differences in disagreement with the negligible arm-leg pressure difference.     

Age‐associated vascular inflammation promotes monocytosis during atherogenesis

Aging leads to a proinflammatory state within the vasculature without disease, yet whether this inflammatory state occurs during atherogenesis remains unclear. Here, we examined how aging impacts atherosclerosis using Ldlr^?/? mice, an established murine model of atherosclerosis. We found that aged atherosclerotic Ldlr^?/? mice exhibited enhanced atherogenesis within the aorta. Aging also led to increased LDL levels, elevated blood pressure on a low‐fat diet, and insulin resistance after a high‐fat diet (HFD). On a HFD, aging increased a monocytosis in the peripheral blood and enhanced macrophage accumulation within the aorta. When we conducted bone marrow transplant experiments, we found that stromal factors contributed to age‐enhanced atherosclerosis. To delineate these stromal factors, we determined that the vasculature exhibited an age‐enhanced inflammatory response consisting of elevated production of CCL‐2, osteopontin, and IL‐6 during atherogenesis. In addition, in vitro cultures showed that aging enhanced the production of osteopontin by vascular smooth muscle cells. Functionally, aged atherosclerotic aortas displayed higher monocyte chemotaxis than young aortas. Hence, our study has revealed that aging induces metabolic dysfunction and enhances vascular inflammation to promote a peripheral monocytosis and macrophage accumulation within the atherosclerotic aorta.     

Investigation of hemodynamics in the development of dissecting aneurysm within patient-specific dissecting aneurismal aortas using computational fluid dynamics (CFD) simulations

Aortic dissecting aneurysm is one of the most catastrophic cardiovascular emergencies that carries high mortality. It was pointed out from clinical observations that the aneurysm development is likely to be related to the hemodynamics condition of the dissected aorta. In order to gain more insight on the formation and progression of dissecting aneurysm, hemodynamic parameters including flow pattern, velocity distribution, aortic wall pressure and shear stress, which are difficult to measure in vivo, are evaluated using numerical simulations. Pulsatile blood flow in patient-specific dissecting aneurismal aortas before and after the formation of lumenal aneurysm (pre-aneurysm and post-aneurysm) is investigated by computational fluid dynamics (CFD) simulations. Realistic time-dependent boundary conditions are prescribed at various arteries of the complete aorta models. This study suggests the helical development of false lumen around true lumen may be related to the helical nature of hemodynamic flow in aorta. Narrowing of the aorta is responsible for the massive recirculation in the poststenosis region in the lumenal aneurysm development. High pressure difference of 0.21 kPa between true and false lumens in the pre-aneurismal aorta infers the possible lumenal aneurysm site in the descending aorta. It is also found that relatively high time-averaged wall shear stress (in the range of 4-8 kPa) may be associated with tear initiation and propagation. CFD modeling assists in medical planning by providing blood flow patterns, wall pressure and wall shear stress. This helps to understand various phenomena in the development of dissecting aneurysm.     

Computational model for simulation of vascular adaptation following vascular access surgery in haemodialysis patients

An important number of surgical procedures for creation of vascular access (VA) in haemodialysis patients still results in non-adequate increase in blood flow (non-maturation). The rise in blood flow in arteriovenous shunts depends on vascular remodelling. Computational tools to predict the outcome of VA surgery would be important in this clinical context. The aim of our investigation was then to develop a 0D/1D computational model of arm vasculature able to simulate vessel wall remodelling and related changes in blood flow. We assumed that blood vessel remodelling is driven by peak wall shear stress. The model was calibrated with previously reported values of radial artery diameter and blood flow after end-to-end distal fistula creation. Good agreement was obtained between predicted changes in VA flow and in arterial diameter after surgery and corresponding measured values. The use of this computational model may allow accurate vascular surgery planning and ameliorate VA surgery outcomes.     

Carcinoma of the rectum; low abdominal transverse incision for resection with end-to-end anastomosis

On the basis of published studies of the lymphatic spread of carcinoma of the rectum, tumors lying as low as the anterior peritoneal reflection may be treated by segmental resection with end-to-end anastomosis. Statistics of five-year survivals in these published studies indicate that for tumors in such locations, a segmental resection offers the same chance for cure as an abdominoperineal resection. The transverse low abdominal incision previously described by the author permits better exposure, facilitates the performance of anastomosis which can be made at a greater depth, and thus enables the surgeon to resect a wider margin distal to the tumor.     

Enhancement of phospholipase C delta 1 activity in the aortas of spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR), which develop hypertension approximately 10 weeks after birth, are considered to provide a good animal model for human essential hypertension. We report here that the abnormal activation of phospholipase C delta 1 (PLC-delta 1) may be one of the main causes of hypertension. Levels of the second messengers inositol 1,4,5-trisphosphate and diacylglycerol are found to be higher in the aortas of 12-week-old SHR than in age-matched normotensive Wistar-Kyoto rats (WKY), although the levels in the aortas of 7-week-old SHR, which have normal blood pressure, are the same as in WKY. Moreover, PLC activity is also higher in the aortas of 12-week-old SHR. Judging from Western blot analysis and immunoabsorption of PLCs, this activation is found to be due to that of PLC-delta 1. PLC-delta 1 from rat aorta is expressed significantly from 7 to 12 weeks, which correlates with the development of hypertension in SHR. The activity of PLC-delta 1 in the aortas of 12-week-old SHR is more markedly activated at low Ca2+ concentration than that of age-matched WKY. These results suggest that the abnormal enhancement of PLC-delta 1 activity is responsible for accumulation of inositol 1,4,5-trisphosphate and diacylglycerol, leading to continuous hypertonicity of vascular smooth muscle in SHR. The activity of PLC-delta 1 in the aortas of 12-week-old SHR is significantly higher at low Ca2+ concentration than that of normotensive WKY.     

CARCINOMA OF THE RECTUM—Low Abdominal Tranverse Incision for Resection with End-to-End Anastomosis

On the basis of published studies of the lymphatic spread of carcinoma of the rectum, tumors lying as low as the anterior peritoneal reflection may be treated by segmental resection with end-to-end anastomosis. Statistics of five-year survivals in these published studies indicate that for tumors in such locations, a segmental resection offers the same chance for cure as an abdominoperineal resection.The transverse low abdominal incision previously described by the author permits better exposure, facilitates the performance of anastomosis which can be made at a greater depth, and thus enables the surgeon to resect a wider margin distal to the tumor.     

The ultrastructure of the blood vessels of Branchiostoma lanceolatum (Pallas) (Cephalochordata)

Summary The ultrastructure of the blood vessels in the caudal region of Branchiostoma is described in specimens injected with indian ink. None of the vessels have endothelial cells delimiting the luminal surface. The vessels are delimited either by dense connective tissue or by the characteristic basement lamella underneath the basal lamina of the myocoelic epithelium. It is proposed that the main blood flow in the caudal region follows different pathways depending on the activity of the animal. During swimming the muscle activity of the caudal muscles may have the effect that more blood flows from the aorta to the myoseptal plexi and is drained to the caudal vessel. In the resting animal it is possible that the blood flow through the myosepta is insignificant, and that the caudal blood flow is more or less restricted to the direct connections between the aorta and the caudal vessel: the dorsoventral anastomosis and the segmental connecting vessels.Supported by a grant from the Danish Natural Science Research Council