Recent strategies to reduce vein graft occlusion: a need to limit the effect of vascular damage

Despite early identification and aggressive modification of atherosclerotic risk factors, many patients still require surgical revascularisation for established atherosclerotic vascular disease. However, bypass surgery is hampered by a high incidence of vein graft failure. New strategies are being introduced to improve these results, with early data suggesting that improved patency rates are possible. These vary from the use of adjuvant pharmacological agents and local gene transfer strategies to the modification of vein harvesting techniques in order to reduce vascular damage to all layers of the graft. Advances in vascular biology have resulted in new insights into the role of the endothelium and adventitia in vein graft remodelling. Although recent pharmacological adjuvant therapy and molecular techniques have been described that may be used to reduce the incidence of vein graft occlusion a more desirable approach for improved graft patency rates may be achieved simply by using atraumatic surgical techniques aimed at minimising vascular damage during vessel harvesting and subsequent anastamoses during bypass surgery.

The European experience with vascular injuries

The rich and diverse heritage of the management of vascular injuries in the 45 independent European countries prevents the authors from revealing a uniform picture of the European experience, but some trends are clearly emerging. In countries with a low incidence of penetrating trauma and increasing use of interventional vascular procedures, the proportion of iatrogenic vascular trauma exceeds 40% of all vascular injuries, whereas on other parts of the continent, armed conflicts are still a major cause of vascular trauma. National vascular registries, mostly in the Scandinavian countries, produce useful, nationwide data about vascular trauma and its management but suffer still from inadequate data collection. Despite a relatively low incidence of vascular trauma in most European countries, the results are satisfactory, probably in most cases because of active and early management by surgeons on call, whether with vascular training or not, treating all kinds of vascular surgical emergencies. In some countries, attempts at developing a trauma and emergency surgical specialty, including expertise in the management of vascular injuries, are on their way.

Shank vessel injuries

The management of lower extremity vascular injuries has undergone dramatic changes over the last century. With the optimal management of femoral and popliteal injuries established, controversy still exists with respect to management of vascular injuries below the popliteal fossa, in the shank arterial vessels. These injuries are uncommon, often limb threatening, and usually require complex management decisions. Incidence of shank vessel injuries, imaging studies required for accurate and expedient diagnosis, determinants influencing the decision for repair or amputation, and details of techniques in surgical intervention are discussed.

Visceral vascular injuries

This article deals with injuries to the celiac trunk, superior and inferior mesenteric arterial injuires. Surgical approaches and physiological implications of interruption of the mesenteric arterial circulation are addressed in detail. Surgical techniques for the management of these injuries and the need for second look operations are also examined.

Brachial and forearm vessel injuries

Upper extremity vascular injuries are common in trauma. The mortality rate from these injuries is quite low; however, the morbidity rate is quite significant. Prompt diagnosis and treatment can reduce the amputation rate for these injuries to minimal. Furthermore, morbidity from late complications of chronic ischemia, restenosis, and cold intolerance can be decreased as well. Fasciotomy, although less frequently required than in lower extremity injuries, should be used in all cases of suspected compartment syndrome.

Vascular trauma in Colombia: experience of a level I trauma center in Medellín

Trauma has become a major health problem in Colombia. The large number of trauma patients has made San Vicente de Paul Hospital of Medellín a major national referred trauma center. Under-reporting is a major problem in Colombia, as in other underdeveloped countries, because of the absence of automated information systems. Despite this and limited financial health resources, time to definitive treatment, morbidity, and mortality are similar to those of centers in developed countries. This article has covered the authors' experience with vascular injuries over a period of 5 years, representing 664 patients; the results were shown in this article. In addition, advances made in the development of new tools for the diagnosis of vascular trauma, such as helical CT angiography, were discussed.

Vascular injury in Australia

Vascular injury poses a small but significant challenge in Australian trauma care. Opportunities such as better practice guidelines and minimum standards will allow surgeons to improve delivery of quality care to the next generation of vascular trauma victims. Training in the management of vascular trauma surgery with integration of vascular and general surgery in trauma care should optimize outcomes. The authors' vision is that all vascular and general surgery trainees would eventually undertake the Definitive Surgical Trauma Care Course and improve vascular trauma outcomes and reduce mortality.

New approaches to trauma management using severity of illness and outcome prediction based on noninvasive hemodynamic monitoring

The mathematical model satisfactorily predicted outcome in acute emergencies based on noninvasively monitored flow, pressure, pulse oximetry, tissue perfusion values, and their cumulative deficits. A decision support system provided information on the relative effectiveness of various therapeutic modalities based on the responses of patients with very similar states. The concept that hypovolemia and oxygen debt is an early primary problem that plays an important role in low flow and poor tissue perfusion states is supported by direct observation of massive hemorrhage, estimated blood loss of hemoperitoneum and hemothorax at the time of surgery, and prior studies in the literature that documented blood volume deficits in posttraumatic and postoperative patients who subsequently developed organ failures and death.

Vascular trauma in high-velocity gunshot wounds and shrapnel-blast injuries in Israel

High-velocity gunshot and shrapnel-blast vascular injuries pose a great challenge and need to be approached in a systematic, multidisciplinary fashion. Early revascularization with temporary shunts, the use of autologous tissue, major venous reconstruction, a low threshold for fasciotomy, and reliable tissue coverage are the mainstays of management.

Vascular trauma and compartment syndromes

Vascular injuries produce ischemia, and their repair produces reperfusion. Ischemia and reperfusion produce compartment syndrome. Although a local event, a compartment syndrome risks not only the affected extremity, but also the life of the patient. A high index of suspicion coupled with adequate knowledge of subtle clinical symptoms (and confirmed by intracompartmental pressure measurement) improve management of compartment syndrome, and this article discusses common pitfalls in its diagnosis and treatment.

Vascular trauma in Latin America: a regional survey

As has been demonstrated, significant differences exist in demographics and the likelihood of accidents among Latin American countries; however, when figures were standardized, they showed a clear similarity in all the reviewed features of vascular trauma. A total of 66.4% of cases were managed solely on a clinical basis, with 78.9% of surgical procedures being performed within 6 hours of injury. Vascular repair was attempted in 84% of arterial injuries and 43% of venous injuries. Results are extremely good, with an 89% rate of success, especially considering that 63% of injuries were gunshot wounds and that the largest series, from Brazil, had a 21.3% rate of abdominopelvic injuries. The mortality rate amounted to 12.7%, but associated injuries, and particularly multiple trauma, account for 50.0% of the deaths.

Complications of vascular injury management

This article addresses failed arterial and venous repairs, thrombosed vessels and bypasses, postoperative pseudoaneurysms and arterio-venous fistulas. Management techniques for these complications are reviewed and morbidity and mortality rates provided.

Penetrating vascular trauma in Johannesburg, South Africa

An awareness that time crucially affects outcome underpins the principles of management of vascular injury. Patients with hard signs of vascular injury should undergo urgent exploration. Soft signs mandate investigation, and arteriography is still the standard of care. Noninvasive vascular imaging may prove its worth in the future. All patients with penetrating arterial injury should receive broad-spectrum antibiotic prophylaxis. Early repair of carotid artery injury provides the best likelihood of a neurologically intact survivor. There is a definite and emerging role of endovascular therapy both for difficult access injuries and for the later complications of vascular injury, such as false aneurysm and arteriovenous fistulas. The experimental and clinical evidence for the use of intraluminal shunts in peripheral vascular injury is compelling, and experience in their use is accumulating. Vascular trauma is complex and ideally is carried out by experts in a multidisciplinary environment; resuscitation and prompt revascularization are likely to lead to satisfactory outcomes. The major trauma load in South Africa represents an unparalleled experience in management of vascular injury, which seems likely to continue for the foreseeable future.

Heroic procedures in vascular injury management: the role of extra-anatomic bypasses

The insertion of an extra-anatomic bypass graft is an accepted operative technique in highly selected patients with atherosclerotic occlusive disease and contraindications to in situ grafting. In similar fashion, the technique should be considered in injured or septic patients with large soft tissue defects or wound infections overlying arterial repairs or involving native arteries. The combination of vigorous débridement of injured or infected soft tissue and insertion of an extra-anatomic bypass graft allows for appropriate care of the wound without concern for further injury to the now-displaced arterial repair.

[A postmortem view on "pure" subdural hemorrhages in infants and toddlers]

In the last years, the discussion concerning the causes of infantile subdural hemorrhages became controversial. Many authors still suppose that child abuse is the predominant cause of such cases. On the other hand, reports presenting series of accidental cases were published, and the fear of an overdiagnosis of the shaken baby syndrome has been expressed. Our autopsy material concerning all lethal head injuries of infants and toddlers from 2 decades was reviewed. 17 of these 64 cases were characterized by the following: history of no trauma or only an insignificant event; children found dead or apnoic or in coma; no skull fractures; no focal brain injury; ruptures of several bridging veins but only minimal subdural bleeding. 11 victims were infants (1st year of life) and either 3 were 2 years resp. 3 - 6 years old; 50 % off all lethal head injuries of infants were of this type, while only 25 % resp. 10 % of the following age groups. None of these 17 cases was a result of a minor accident witnessed by unrelated persons. Abuse could be ascertained with a high degree of probability in most cases and remained quite likely in the others. Two different types of subdural hemorrhages should be kept from another: a) patients suffering a moderate head injury from a minor accident which results in a subdural bleeding (from a small intracranial lesion) often do not deteriorate soon after the impact, develop a hemorrhage of significant volume, respond well to therapy and have a good prognosis. b) cases with a history of no or only of an insignificant trauma, infants dead or nearly dead on clinical presentation, often a poor outcome in cases of survival. There is typically no significant subdural bleeding despite multiple bridging vein ruptures in the majority of these cases: the subdural hemorrhage is here only a visible sign of a much more serious and general cerebral alteration, resulting in a rapid increase of intracranial pressure (often complicated by respiratory arrest) which prevents a signifant bleeding into the subdural space. This combination of findings is typically found in victims of massive events (car occupants in high-velocity crashes) and not compatible with a supposition of a minor fall causing this.

The use of polynomial neural networks for mortality prediction in uncontrolled venous and arterial hemorrhage

BACKGROUND

The ability to rapidly and accurately triage, evacuate, and utilize appropriate interventions can be problematic in the early decision-making process of trauma care. With current methods of prehospital data collection and analysis, decisions are often based upon single data points. This information may be insufficient for reliable decision-making. To date, no studies have attempted to utilize data at multiple time points for purposes of enhancing prediction, nor have studies attempted to synthesize prediction models with data reflecting both large-vessel venous and arterial injuries. Therefore, we performed a retrospective study to examine the potential utility of dynamic neural networks in predicting mortality using highly discretized uncontrolled hemorrhagic shock data.

METHODS

One hundred forty-three swine with either grade V liver injuries or 2.8-mm aortotomies had hemodynamic data collected every minute throughout injury and resuscitation. The independent variables used as inputs to the polynomial neural networks (PNNs) included systolic blood pressure and mean arterial pressure (MAP). These inputs were used to predict mortality in individual swine 1 hour after injury using data up to 20 minutes after injury. Survival models were compared based on discrimination power (DP), i.e., where specificity equals sensitivity, and area under the receiver operating characteristic (ROC) curve (c-statistic). The Hosmer-Lemeshow (H-L) statistic was used to measure model calibration.

RESULTS

The best PNN model predicted mortality at 60 minutes utilizing data from injury to 20 minutes after injury. This model produced a ROC area of 0.919, a DP of 0.857, and a H-L value of 16.47. A DP of 0.857 means that 85.7% of the survivors are correctly predicted to survive, and 85.7% of the nonsurvivors are predicted to die. MAP of survivors and nonsurvivors were graphed for comparative purposes. As this graph illustrates, the use of MAP alone cannot discriminate survivors from nonsurvivors.

CONCLUSION

This study demonstrates that PNN models can effectively harness the dynamic nature of uncontrolled hemorrhagic shock data, despite utilizing data from large-vessel arterial and venous injuries. Utilizing the dynamic nature of hemorrhagic shock data in PNNs may ultimately allow the development of novel decision assist devices.

Management of military vascular injuries

BACKGROUND

Vascular injuries caused by high-velocity military missiles during war present large and extensive defects of tissues and bones, are often associated with other injuries. In this study we will discuss the surgical strategy and results of military vascular injuries.

METHODS

A retrospective review of records of 63 patients treated between January 1995 and December 1999 was undertaken.

RESULTS

The mean age of the wounded was 22.3 years (range, 20 to 37 years). The mean time for evacuation from the place of injury to the hospital was 2.3 hours (range, 15 min to 10 hrs). There were 58 (76.3%) arterial and 18 (23.7) venous injuries. Vascular injuries concomitant with 28 (36.9%) bone fractures, six (7.9%) nerve injuries, nine (11.8%) hemopneumothorax and one (1.3%) abdominal injuries. The treatment of the injured arteries were 39 (51.3%) saphenous vein interposition grafting, 13 (17.1%) end to end anastomosis, 12 (15.7%) primary suture, seven (9.2%) synthetic graft replacement. Three patients (3.9%) died because of hypovolemic shock. Five patients underwent amputation (6.6%) and fasciotomy was performed after vascular repair in 11 cases (14.5%).

CONCLUSIONS

At the military vascular injuries, the right timing, and also prompt treatment save the life of the patients and give better qualified living to the patient.

Monocyte adhesion to human vein grafts: a marker for occult intraoperative injury?

OBJECTIVE

Monocyte adhesion to the vessel wall is believed to be an important initiating event in atherosclerosis and intimal hyperplasia. We hypothesized that occult intraoperative vein injury induces an immediate increase in monocyte adhesion that may be critical to the development of vein graft disease.

METHODS

Vein segments were obtained from patients (n = 23) undergoing lower extremity bypass. The initial segment (V1, n = 17) was excised immediately at the time of conduit harvest. A second segment (V2, n = 23) was obtained from the distal conduit just before performing the distal anastomosis. Segments were incubated with radiolabeled THP-1 cells (monocytoid cell line) for 1 hour at 37 degrees C, then rinsed and solubilized for determination of bound radioactivity. In a subset of grafts (n = 4), THP-1 cells were preincubated with monoclonal antibody (mAB) 7E3 (which binds to the monocyte integrin Mac-1 at its fibrinogen [Fg]-binding site) or control (mAB 14E11). Fg deposition and endothelial coverage were evaluated by immunohistochemistry (n = 10). Statistical analysis was performed using the paired t test and analysis of variance. Follow-up graft patency data were obtained and correlated with adhesion values using an exact test (StatXact, Cytel Software, Cambridge, Mass).

RESULTS

Monocyte adhesion was significantly increased after surgical manipulation (V1, 2400 +/- 770 versus V2, 7343 +/- 1555 cells/cm(2); P <.02). Fg deposition was abundant in V2 sections and not seen in V1. Monocyte adhesion to V2 segments was significantly reduced (58% of control, P <.01) by 7E3 treatment. Graft follow-up was complete with a mean interval of 11 months. Higher V2 adhesion values were associated with occluded grafts (P =.07). The median value for the six occluded grafts was 6234 cells/cm(2) versus 3892 cells/cm(2) for the 17 patent grafts.

CONCLUSIONS

Monocyte adhesion to the vein wall is immediately increased after surgical manipulation and is inhibited by mAB 7E3. Early monocyte adhesion to vein grafts is likely to involve interactions between Mac-1 and Fg. Heightened levels of monocyte adhesion at implantation may be a marker for subsequent vein graft failure.

[Major vascular and neural complications in varicose vein surgery. Prospective documentation of complication rate in surgery of the V. saphena magna and V. saphena parva]

The complication rate in varicose vein surgery has not been viewed separately for the sapheno-femoral and the saphenopopliteal junction. From 1.10.1988 to 31.12.99 we prospectively registered the major vascular and neural complication rate. A total of 31,838 ligations of the saphenofemoral junction and 6,152 ligations of the saphenopopliteal junction were performed. There were seven major vascular injuries (0.017%) and three major neural injuries (0.0074%). The specific risk at the saphenofemoral junction amounts to: major venous injury n = 4 (0.013%) without development of a postthrombotic syndrome (PTS); no arterial injury and no major neural injury. At the saphenopopliteal junction we found three major venous injuries (0.049%) with development of PTS in all cases. There were three major neural injuries (0.049%) with complete regeneration in two cases and one permanent paresis of digit V. Since operations on the saphenopopliteal junction show a higher risk of major vascular und major neural injury, flush ligation of the saphenopopliteal junction should not be forced in every case.

Venous obstruction caused by a self-adhesive drape: a cautionary tale

The use of disposable drapes during operations is becoming more widespread, and their advantages are well documented. I describe how use of such a drape led to venous constriction which caused troublesome oozing from the operative sites during sagittal split osteotomy. When the drape was removed, there was a clear red indentation on the patient's neck, and the bleeding stopped immediately. The patient made an uneventful recovery.

Potential of increased risk of neurovascular injury using proximal interlocking screws of retrograde femoral nails in patients with acetabular fractures

OBJECTIVES

Neurologic and vascular structures are at risk of iatrogenic injury from proximal interlocking screw insertion after retrograde nailing. This risk may increase in the presence of acetabular fractures because of the displacement of soft tissues resulting from hematoma. The purpose of this study was to establish and compare the relative safe zones (RSZs) for interlocking screw insertion in adults with and without concomitant acetabular fractures.

MATERIALS AND METHODS

Thirty pelvic computed tomography scans of patients with acute unilateral acetabular fracture and magnetic resonance imaging scans of five healthy legs were used to evaluate the course of the femoral sheath, neurovascular complex, and the sciatic nerve as they course through the proximal thigh in sixty-five limbs.

RESULTS

The anatomy of the neurovascular structures on the fractured side was statistically different from that of the normal side. On the normal side, the RSZ at the lesser trochanteric level was identified from +7 degrees medial to +20 degrees lateral to the sagittal axis (27-degree angle zone) for anteroposterior screw placement. These values for the fractured side, respectively, changed to +1 degrees and +14 degrees (13-degree angle zone), a 52 percent decrease. The RSZ for lateral-medial screw placement was 28 degrees anterior to 39 degrees posterior to the coronal axis (67-degree angle zone) for the normal side, which changed, respectively, to 32 degrees and 41 degrees (73-degree angle zone) for the fractured side. At the level of the lesser trochanter, rotation in the femoral shaft was mimicked only in part (approximately 50 percent) by the neurovascular structures.

CONCLUSION

Lateral-medial screw insertion is safer than anteroposterior insertion. Anteroposterior screw insertion becomes even more critical if the acetabulum is fractured. Femoral external rotation after rod insertion, but before screw insertion, will enlarge the safe zones.

Factors affecting mortality rates in patients with abdominal vascular injuries

BACKGROUND

Major vessel injury is seen in 5% to 25% of patients admitted to hospitals with abdominal trauma, and this is the most common cause of death in these patients.

METHODS

Data on 470 patients with abdominal vascular injuries seen at a Level I trauma center were reviewed retrospectively.

RESULTS

The overall mortality rate was 45%. The incidence of various types of trauma were blunt in 51 patients (11%), gunshot wounds in 329 patients (70%), shotgun wounds in 21 patients (4%), and stab wounds in 69 patients (15%). The three vessels with the highest mortality rates were aorta (at and proximal to the renals) (32 of 35 [91%]), hepatic veins and/or retrohepatic vena cava (36 of 41 [88%]), and portal vein (25 of 36 [69%]). The most significant risk factors (p < 0.001) for death were a trauma score of 9 or less, initial operating room (OR) systolic blood pressure (SBP) < 90 mm Hg, final OR core temperature < 34 degrees C, 10 or more blood transfusions in the first 24 hours, and an initial emergency department SBP < 70 mm Hg. Of 120 patients with an initial OR SBP < 70 mm Hg, 103 (86%) died. Of 29 patients with a good response to a prelaparotomy thoracotomy with thoracic aortic cross-clamping (SBP > 90 mm Hg within 5 minutes), 11 (38%) survived. Of the remaining 87 patients, only 6 (7%) survived (p = 0.01).

CONCLUSION

Rapid control of bleeding sites (to keep blood transfusions to < 10 units) and urgent correction of hypothermia seem to be the main factors improving survival over which the surgeon has some control.

Pathophysiology and diagnosis of deep venous thrombosis

Lower-limb deep venous thrombosis (DVT) affects between 1% to 2% of hospitalized patients. These thrombi disrupt the vascular integrity of the lower limbs and are the source of emboli that kill approximately 200,000 patients each year in the United States. The causes of thrombosis include vessel wall damage, stasis or low flow, and hypercoagulability. These factors favor clot formation by disrupting the balance of the opposing coagulative and fibrinolytic systems. The symptoms and signs of venous thrombosis are caused by obstruction to venous outflow, vascular inflammation, or pulmonary embolization. About 70% of patients referred for clinically suspected venous thrombosis, however, do not have the diagnosis confirmed by objective testing. Among the 30% who have venous thrombosis, about 85% have proximal vein thrombosis, and the remainder have thrombosis confined to the calf. Physicians cannot rely on signs and symptoms to make the diagnosis of DVT and must depend on imaging studies to guide treatment. Patients with proximal vein thrombosis who are inadequately treated have a 47% frequency of recurrent venous thromboembolism over 3 months. In contrast, clinically detectable recurrence occurs in less than 2% of patients with proximal vein thrombosis if an adequate anticoagulant response is achieved. Of the diagnostic procedures for DVT, venography is the only invasive test of proven value, and ultrasonographic (US) studies are the most commonly used noninvasive modaity. Other procedures are occasionally used to diagnose DVT, including impedance plethysmography, computed tomography, and magnetic resonance imaging. US examinations are noninvasive, they are rapidly obtained, and they can be performed serially. In symptomatic patients, venous US is sensitive and specific for proximal DVT; however, US is insensitive to calf vein thrombosis and to asymptomatic DVT occurring after surgery. Patients with symptoms of recurrent DVT also can present a difficult diagnostic problem. Only about 20% to 30% of these individuals actually have the disease; the rest have symptoms arising from chronic venous insufficiency or from any of the causes of lower extremity pain. After an acute episode, up to 50% of patients have compression ultrasound abnormalities for 6 months that are indistinguishable from the original findings of DVT. Hence, there are a significant number of patients and clinical circumstances in which the diagnosis of DVT is difficult. 99mTc-radiolabeled peptides that target the molecular biology of thrombosis should aid in the management of the disease, particularly in asymptomatic patients at high risk, in patients with recurrent symptoms, in patients with active DVT in the calf and/or pelvis, and in patients with intermediate- or low-probability lung scans.