Blood coagulation and fibrinolytic response after endovascular stent grafting of thoracic aorta

Disseminated Intravascular Coagulation Post Endovascular Aortic Repair

BACKGROUND

Disseminated Intravascular Coagulation (DIC) after Endo-Vascular Aneurysm Repair (EVAR) is a highly uncommon clinical entity. With only a few case-reports available, its management strategy still remains enigmatic.

OBJECTIVES

The purpose of this study was to retrieve, synthesize, and appraise all existing data for DIC after EVAR.

MATERIALS AND METHODS

All published articles regarding DIC post-EVAR were identified from 3 major databases and analyzed. Clinical parameters, predisposing factors, along with mortality and morbidly were assessed.

RESULTS

The total number of publications included in the review was 15 describing 17 cases. DIC presented with a broad spectrum of clinical manifestations, while the time of diagnosis varied significantly. Endoleak was the main causative factor, with an incidence reaching 71%. The mortality of DIC after EVAR reached 29%, regardless of the therapeutic approach chosen. DIC was treated effectively in 47% of the patients (8/17), with better outcomes among patients who received conservative therapy or among those who were submitted to endovascular interventions.

CONCLUSIONS

DIC after EVAR, although rare, is a potentially lethal clinical condition which requires prompt diagnosis and urgent medical consideration. Treatment of endoleak may help in quick restoration of normal parameters.

Platelet function changes in patients undergoing endovascular aortic aneurysm repair: Review of the literature

Patients with abdominal aortic aneurysm (AAA) have a higher risk of cardiovascular (CV) events, which seems to be associated with disturbed platelet (PLT) function. Endovascular aneurysm repair (EVAR) is an emerging, less-invasive treatment alternative to surgical AAA repair. Both platelet function abnormalities in patients with AAA and the effect of EVAR on platelet function are poorly understood. In this review, we aim to fill the gap regarding the effect of EVAR on PLT function in AAA patients by discussing PLT function disturbances in patients with AAA, PLT function changes after EVAR, evidence from clinical studies regarding PLT function before and after EVAR, and antiplatelet or and antithrombotic treatment in patients undergoing EVAR. The goal of our review is to summarize the contemporary knowledge and initiate further studies to better understand PLT function changes in patients undergoing EVAR, optimize the pharmacotherapy before and after EVAR and further improve outcomes in this group of patients.

Platelet Depletion after Thoraco-Abdominal Aortic Aneurysm Endovascular Repair is Associated with Clinically Relevant Hemorrhagic Complications

BACKGROUND

Thoraco-abdominal endovascular aortic repair (TA-EVAR) can be associated with platelet depletion (PD); the present study aims to evaluate PD incidence after TA-EVAR and to investigate its possible predictors and its influence on hemorrhagic complications and mortality.

METHODS

A retrospective analysis of all TA-EVAR from 2010 to 2021 was performed to identify patients with PD, (reduction > 60%). Spontaneous hemorrhages considered were: intracranial or any hemorrhages requiring surgery. Risk factors for PD, correlation with hemorrhagic complications and 30-day mortality were investigated by uni/multivariate analysis.

RESULTS

A total of 158 TA-EVAR were considered, 35(22%) female, 86(54%) extended thoraco-abdominal aortic aneurysm (TAAA) (Crawford type I, II, III), 79(50%) staged procedure, 31(20%) urgent treatment (symptomatic/ruptured). PD was identified in 42 (27%) patients and correlated to female sex, thrombus-free aortic lumen > 50mm, urgent treatment, extensive TAAA, blood transfusion >3 units and staged procedure at the univariate analysis. The multivariate analysis confirmed a significant correlation between PD and thrombus-free aortic lumen > 50mm, urgent treatment, blood transfusion > 3 units and staged procedure (odds ratio [OR]: 2.5 (95% confidence interval [CI] 1.03-7.0), P = 0.04, OR 3.2 (95% CI 1.01-8.6), P= 0.03, OR 3.16 (95% CI 1.23-7.7), P = 0.03 and OR 2.71 (95% CI 1.2-6.2), P= 0.04, respectively). Overall, 13 hemorrhagic complications occurred (8 intracranial and 5 peripheral); PD was associated with higher risk of hemorrhagic complications (9/42 - 21% vs. 4/116 - 3%, OR: 7.6 [95% CI: 2.2-26.3], P= 0.001) and a higher risk of 30-day mortality in elective cases 4/25 - 16% vs. 3/101 - 3%, OR: 6.2 (95% CI: 1.3-29.8), P= 0.03.

CONCLUSIONS

PD is a relatively common event after TA-EVAR and is associated with thrombus-free aortic lumen > 50mm, urgent treatment, blood transfusion > 3 units and staged procedure. Hemorrhagic complications and mortality are increased under these circumstances.

Post-implantation syndrome after frozen elephant trunk is associated with the volume of new-onset aortic thrombus

Background

Post-implantation syndrome (PIS) is defined as non-infectious continuous fever and a concomitant rise in inflammatory markers shortly after endovascular aortic repair. PIS occurrence after hybrid procedures, such as the frozen elephant trunk (FET) technique, has not been adequately investigated. The current study aims to define the incidence of PIS after the FET and to identify possible risk factors associated with its occurrence.

Methods

The clinical charts of 59 patients undergoing the FET between February 2015 and April 2020 were reviewed retrospectively. The occurrence of PIS was defined as the presence of fever (>38 °C lasting longer than one day during the hospitalisation) and leucocytosis (white blood cell count >12,000/µL). Patients with concomitant conditions possibly leading to fever and/or leucocytosis were excluded. Beside demographic and procedure-related data, serum/plasma inflammatory markers were evaluated before surgery and daily up to seven days postoperatively. Computed tomography scans (CT) were examined to calculate the volume of pre-existent and new-onset mural thrombus after the FET.

Results

Thirty-eight patients met the inclusion criteria. The study cohort was divided into two groups based on the occurrence of PIS (17 cases; 44.7%). Patients with PIS were significantly younger than those without PIS (53.5±8.9 vs. 62.5±9.6 years; P=0.005). Female patients were less likely to develop PIS (5.2% vs. 26.3%, P=0.018). Patients with PIS had a higher volume of new-onset thrombus in the postoperative CT (P<0.001). Patients treated for post-dissection aneurysm had, postoperatively, significantly more thrombus material developed in a false lumen (P=0.02). Among the PIS markers, CRP (C-reactive protein) levels on the third postoperative day were independently associated with the volume of new-onset thrombus (P=0.011). After multivariate analysis, the volume of new-onset thrombus (P=0.028) and age (P=0.036) remained the variable associated with a statistically significant increased incidence of PIS.

Conclusions

PIS can occur after the frozen elephant trunk procedure. The volume of new-onset thrombus seems to be associated with an increased incidence of PIS. These findings need to be confirmed in larger patient cohorts.

Intracranial Hemorrhage After Endovascular Repair of Thoracoabdominal Aortic Aneurysm

BACKGROUND

Intracranial hemorrhage (ICH) is a rare but devastating complication of thoracoabdominal aortic aneurysm (TAAA) repair with fenestrated/branched endograft (f/bEVAR). The cerebrospinal fluid drainage (CSFD) is considered one of the leading causes; however, other possible concomitant factors have not been individualized yet. The aim of the present work was to evaluate the pattern of ICH events after f/bEVAR for TAAA and to identify possible associated factors.

MATERIALS AND METHODS

All f/bEVAR procedures for TAAA performed in a single academic center from 2012 to 2020 were evaluated. ICH was assessed by cerebral computed tomography if neurological symptoms arose. Pre-, intra-, and postoperative characteristics were analyzed in order to identify possible factors associated.

RESULTS

A total of 135 f/bEVAR were performed for 72 (53%) type I, II, III and 63 (47%) type IV TAAA; 74 (55%) were staged procedures, 101 (73%) required CSFD, and 24 (18%) were performed urgently. The overall 30-day mortality was 8% (5% in elective cases); spinal-cord ischemia occurred in 11(8%) and ICH in 8 (6%) patients. All ICH occurred in patients with CSFD. ICH occurred intraoperatively in 1 case, inter-stage in 4 and after F/BEVAR completion in 3, after a median of 6 days the completion stage. Three (38%) of 8 patients with ICH died at 30 days and ICH was associated with 30-day mortality: odds ratio (OR) 13.2, 95% confidence interval (CI): 2.3-76, p=0.01. The analysis of the perioperative characteristics identified platelet reduction >60% (OR 11, 95% CI 1.6-77, p=0.03), chronic kidney disease (16% vs 0%, p=0.002), and total volume of liquor drained >50 mL (OR 8.1, 95% CI 1.1-69, p=0.03) as associated with ICH.

CONCLUSIONS

Current findings may suggest that ICH is a potential lethal complication of the endovascular treatment for TAAAs and it mainly occurs in patients with CSFD. High-volume liquor drainage, platelet reduction, and chronic kidney disease seems increase significantly the risk of ICH and should be considered during the perioperative period and for further studies.

Preoperative disseminated intravascular coagulation complicated by thoracic aortic aneurysm treated using recombinant human soluble thrombomodulin: A case report

RATIONALE

Chronic disseminated intravascular coagulation (DIC) associated with thoracic aortic aneurysm is characterized by enhanced fibrinolysis and is thought to be stable in the compensated/asymptomatic stage, with few bleeding symptoms. However, DIC can lead to decompensated/hemorrhagic stage disseminated intravascular coagulation, resulting in severe bleeding diathesis, and there is currently no established strategy for treatment of DIC in aortic aneurysms.

PATIENT CONCERNS

A 77-year-old woman underwent angiography and cardiac catheterization, before descending aortic replacement surgery. She developed DIC in postprocedure week 2 with extensive, uncontrollable massive subcutaneous hemorrhage.

DIAGNOSES

Her acute-phase DIC score was 7 points, and the risk of mortality within 30 days after surgery according to the JapanSCORE was estimated to be 33.6%.

INTERVENTIONS

Therapy was a combination of recombinant human soluble thrombomodulin (rhTM) and an aortic stent-graft treatment.

OUTCOMES

Short-term improvements were seen in both DIC and bleeding diathesis. The thoracic aortic aneurysm with severe DIC was eventually corrected by administration of rhTM.

LESSONS

We report the use of rhTM as an effective, novel anticoagulant drug with anti-inflammatory activity for treating DIC with suppressed fibrinolysis, which is typically associated with sepsis. In patients with a high hemorrhagic diathesis, in whom preoperative control of DIC cannot be achieved with conventional anticoagulation and radical surgical repair cannot be performed, a combination of rhTM and endovascular therapy may be a powerful new treatment option.

Association between platelet counts and morbidity and mortality after endovascular repair for type B aortic dissection

This study aimed to assess the association of postoperative platelet counts with early and late outcomes after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD). We retrospectively evaluated 892 patients with TBAD who underwent TEVAR from a prospectively maintained database. Postoperative nadir platelet counts were evaluated as a continuous variable, and a categorical variable (thrombocytopenia), which was defined as platelet count≤ the lowest 10% percentile (108 × 10⁹/l). Multivariable logistic regression analyses were conducted to assess the impact of postoperative thrombocytopenia on early outcomes, and multivariable cox regression analyses on long-term mortality. Patients with postoperative thrombocytopenia experienced significantly higher rates of postoperative mortality, prolonged intensive care unit stay, death, stroke, limb ischemia, mesenteric ischemia, acute kidney injury (AKI), and puncture-related hematoma (P< .05 for each), but similar rates of immediate type I endoleak and spinal cord ischemia. Multivariable logistic analyses showed that postoperative thrombocytopenia was independently associated with postoperative stroke, limb ischemia, and AKI. Similar results were observed when postoperative nadir platelet count was modeled as a continuous predictor (P< .05 for each). By multivariable Cox analyses, postoperative thrombocytopenia was an independent predictor for long-term all-cause mortality (hazard ratio 2.72, 95% CI, 1.72-4.29, P< .001). For every 30 × 10⁹/L decrease in postoperative platelet count, the risk of long-term all-cause mortality increased by 15% (HR 1.15; 95% CI 1.07-1.25; P< .001). Therefore, postoperative thrombocytopenia might be a useful tool for risk stratification after TEVAR.

Delayed disseminated intravascular coagulopathy post thoracic endovascular aortic repair (TEVAR)

Disseminated intravascular coagulopathy (DIC) is a very rare outcome post endovascular repair of aortic aneurysm dissections. We present a case of a 70-year-old male who presented with DIC post a thoracic endovascular aortic repair (TEVAR) procedure due to a type 1A endoleak. Initially, the patient was treated with red blood cells and blood products; however, when failing to improve, he underwent a hybrid arch replacement. In this study, we will analyze the management of DIC post TEVAR and look at its presentation more extensively, as it is currently a topic that is poorly studied.

Association Between Perioperative Fibrinogen Levels and the Midterm Outcome in Patients Undergoing Elective Endovascular Repair of Abdominal Aortic Aneurysms

BACKGROUND

We investigated the potential association between perioperative fibrinogen levels and outcome in patients undergoing elective endovascular abdominal aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs).

METHODS

Consecutive patients with an intact AAA undergoing elective EVAR with a specific bifurcated endograft (Endurant, Medtronic) were recruited between December 2012 and October 2016. Preoperative and 24-hr postoperative fibrinogen levels were recorded, and potential associations with outcome were tested. Primary outcome measures included endoleaks, lower limb ischemic complications, including endograft limb occlusion, and aneurysm-related reinterventions.

RESULTS

Ninety-four patients (91 male, mean age 71.8 ± 8.0 years) with an intact AAA were enrolled in the study. The technical success was 98% (2 failures: 1 type Ia endoleak on completion angiography, 1 lower limb ischemia immediately postoperatively requiring femoral endarterectomy). There was 1 death during the first 30 days due to myocardial infarction (1%). Another patient died 15 months after the procedure from cardiac causes. During the existing follow-up (mean 14.8 ± 14.3 months), 14 patients (15%) developed an endoleak (4, type Ia endoleak and 10, type II endoleak), 6 patients (6.3%) had lower limb ischemia/endograft limb occlusion, and 10 patients (10.6%) required reintervention. Compared with the preoperative values, no significant change occurred with regard to the fibrinogen levels 24 hr after procedure (mean preoperative fibrinogen 360 ± 101 mg/dl vs 24-hr postoperative fibrinogen 349 ± 105 mg/dl, P = 0.1). Neither preoperative nor 24-hr postoperative fibrinogen levels were significantly associated with the development of endoleaks, lower limb ischemia, or reinterventions. However, the difference in fibrinogen levels (baseline to 24 hr after procedure) was significantly higher in patients with endoleaks (median -65 mg/dl vs. 15 mg/dl, P = 0.04).

CONCLUSIONS

Perioperative fibrinogen levels may play a role in predicting midterm outcomes in patients undergoing elective EVAR and appears to be associated, directly or indirectly, with the development of endoleaks. Further studies are needed to investigate these findings and explore future therapeutic implications.

Spinal cord injury after thoracic endovascular aortic aneurysm repair

PURPOSE

Thoracic endovascular aortic aneurysm repair (TEVAR) has become a mainstay of therapy for aneurysms and other disorders of the thoracic aorta. The purpose of this narrative review article is to summarize the current literature on the risk factors for and pathophysiology of spinal cord injury (SCI) following TEVAR, and to discuss various intraoperative monitoring and treatment strategies.

SOURCE

The articles considered in this review were identified through PubMed using the following search terms: thoracic aortic aneurysm, TEVAR, paralysis+TEVAR, risk factors+TEVAR, spinal cord ischemia+TEVAR, neuromonitoring+thoracic aortic aneurysm, spinal drain, cerebrospinal fluid drainage, treatment of spinal cord ischemia.

PRINCIPAL FINDINGS

Spinal cord injury continues to be a challenging complication after TEVAR. Its incidence after TEVAR is not significantly reduced when compared with open thoracoabdominal aortic aneurysm repair. Nevertheless, compared with open procedures, delayed paralysis/paresis is the predominant presentation of SCI after TEVAR. The pathophysiology of SCI is complex and not fully understood, though the evolving concept of the importance of the spinal cord's collateral blood supply network and its imbalance after TEVAR is emerging as a leading factor in the development of SCI. Cerebrospinal fluid drainage, optimal blood pressure management, and newer surgical techniques are important components of the most up-to-date strategies for spinal cord protection.

CONCLUSION

Further experimental and clinical research is needed to aid in the discovery of novel neuroprotective strategies for the protection and treatment of SCI following TEVAR.

Fatal Hemorrhage from Kidney after Endovascular Repair for Chronic Type B Dissection Complicated with Disseminated Intravascular Coagulation

We report lethal hemorrhage from the kidney after thoracic endovascular repair for chronic type B dissection complicated by disseminated intravascular coagulation (DIC). A 70-year-old woman underwent thoracic endovascular repair to treat chronic DIC. Two weeks after surgery, refractory shock suddenly occurred and computed tomography showed a massive hematoma around the left kidney. Emergent renal artery angiography showed multiple bleeding points in the renal cortex. Immediate embolization of the renal artery was performed and her hemodynamic condition recovered. Physicians should be aware that massive hemorrhage from visceral organs is possible during the perioperative period of endovascular intervention for treatment of DIC.

Endovascular Repair For Thoracic Aortic Disease: Tertiary Single-center Experience In Northwestern Greece

The purpose of this article is to report the initial experience with endovascular repair of thoracic aortic disease in a single tertiary vascular unit in northwestern Greece.

Between 2003 and 2005, 16 patients were treated with endovascular techniques for various pathologies of the descending thoracic aorta. Twelve patients were treated electively and four emergently. Operative and follow-up data for a mean time of 18.4 months were retrospectively collected and analyzed.

Primary technical success was obtained in 14 (87.5%) cases. No early or late deaths occurred, and there was no major operation-related complication. No paraplegia was observed in our patients. Stent graft–related complications occurred in 18.75% (one type 2 and two type 3 endoleaks), but they all had a favorable outcome. No further problems have been reported in any of our patients.

Endovascular stent graft repair for diseases of the thoracic aorta seems to be a promising alternative to open surgery, especially for high-risk patients. Long-term results are needed to confirm the early benefit of this treatment option with regard to morbidity and mortality rates. The potential of this technique to be applicable even in relatively small, tertiary vascular centers might be of great benefit to patients.

A Case of Disseminated Intravascular Coagulation after Thoracic Endovascular Aortic Repair

I report a hemorrhagic complication due to disseminated intravascular coagulation after thoracic endovascular aortic repair for a dissecting aortic aneurysm. A 74-year-old man underwent thoracic endovascular aortic repair and carotid-carotid artery bypass to close the primary entry site of the dissecting aortic aneurysm. Postoperatively, he developed a gradually expanding cervical hematoma. Laboratory data showed disseminated intravascular coagulation. He could not extubated until postoperative day 6 because of the risk of airway obstruction. He was treated with transfusion to replenish the coagulation factor. Disseminated intravascular coagulation may occur secondary to thrombus formation in the false lumen after thoracic endovascular aortic repair.

Staged hybrid repair using telescoped stent graft fixation for aortic arch and descending aortic aneurysms

Staged repair of extensive thoracic aortic aneurysms is complicated, with a high incidence of interval rupture between stages. We describe the systematic staged hybrid procedure of a previous endovascular repair of a descending aortic aneurysm and open surgical repair of an aortic arch aneurysm. In the second-stage arch repair, the stent graft was easily retracted and fixed, without dissection, around the aortic arch aneurysm distal side. Extensive thoracic aortic aneurysms were managed without interim rupture or neurologic deficits. This approach avoided the potential for interim rupture because recovery from the first-stage endovascular repair was shorter than that from open repair.

Fibrinogen/fibrin degradation products in acute aortic dissection

BACKGROUND

The elevated D-dimer value is one of the clues used to diagnose acute aortic dissection (AAD), but the rapid D-dimer assay is not used at all emergency hospitals. The fibrinogen/fibrin degradation products (FDP) value is also an indicator of enhanced fibrinolysis and may therefore be a useful marker in patients with AAD. In addition, the association between FDP values and partial thrombosis of the false lumen is not elucidated.

PATIENTS

The present study enrolled 50 patients (66.5±11.2 years of age; median, 66.5 years of age, male subjects comprised 60.0% of the series) with AAD who were admitted to the hospital between July 2005 and December 2007 and 57 patients with acute myocardial infarction (AMI; 70.8±10.4 years of age; median, 71.0 years of age, male subjects comprised 71.9% of the current series) served as a control group.

RESULTS

The FDP values (µg/mL) in patients with AAD were significantly higher than those of AMI patients (40.2±78.6; median, 14.7 vs. 5.2±9.8; median, 1.7, p<0.001). A receiver operating characteristic curves analysis showed that an elevated FDP level (2.05 µg/mL) was predictive of a diagnosis of AAD with a sensitivity and specificity of 98% and 54%, respectively. The FDP levels of patients (n=14) who had partial thrombosis of the false lumen were significantly higher than in discharged patients without a surgical repair (n=21) who had a patent or complete thrombosis of the false lumen (35.8±43.2; median, 18.8 vs. 14.0±21.3; median, 5.5, p=0.01).

CONCLUSION

The measurement of FDP may therefore be useful for the initial assessment of patients with suspected AAD and in the prediction of thrombotic status of the false lumen.

Deteriorating consumptive coagulopathy with type III endoleak following endovascular repair for abdominal aortic aneurysm associated with liver cirrhosis

PURPOSE

To report a case of deteriorating consumptive coagulopathy with type III endoleak following endovascular aneurysm repair (EVAR) of the abdominal aorta associated with liver cirrhosis.

CASE REPORT

A 72-year-old man with liver cirrhosis developed type III endoleak following EVAR. Spontaneous intramuscular hematoma developed due to deteriorating consumptive coagulopathy induced by type III endoleak and liver dysfunction. Although additional EVAR was performed at 52 months after primary EVAR, the patient died due to multiorgan failure and multifocal hematoma of the muscles and subserosa.

CONCLUSION

EVAR for patients with liver dysfunction and coagulopathy should be considered with great caution. We suggest that prompt and adequate treatment using an endovascular technique or surgical repair should be performed for patients with liver dysfunction, coagulopathy, and turbulent endoleak, even if the coagulopathies are worse compared to before EVAR.

Perioperative Management to Improve Neurologic Outcome in Thoracic or Thoracoabdominal Aortic Stent-Grafting

BACKGROUND

Thoracic or thoracoabdominal aortic stent-graft repair has shown a reduction in morbidity and mortality rates due to the procedure's advantages (no aortic cross-clamping, continuous distal aortic perfusion, no reperfusion injury). However, 3% to 12% of the patients are at risk of spinal cord ischemia. We investigated spinal cord protective measures with evoked potentials, cerebrospinal fluid drainage, and prevention of hypotension to minimize postoperative neurologic deficit.

METHODS

Between November 2000 and July 2005, vital parameters and spinal cord function were monitored, including cerebrospinal fluid pressure and transcranial motor-evoked and somatosensory-evoked potentials in 36 stent-graft procedures (31 patients) on the thoracic or thoracoabdominal aorta.

RESULTS

Stent-graft placement was technically successful in all patients. We achieved a survival rate of 100% without neurologic deficit after fast-track extubation. Eleven of 31 patients exhibited changes in evoked potentials during stent-graft deployment. In 12 of 31 patients (including the 11 with evoked potential alterations), cerebrospinal fluid pressure exceeded 15 mm Hg. Cerebrospinal fluid drainage and vital parameter adjustment were executed in those instances. We observed intraoperative evoked potential total recovery in 10 of 11 patients after these interventions.

CONCLUSIONS

Interventions to improve spinal cord perfusion led to total recovery of spinal function in most patients (10/11). Therefore, spinal cord protective measures with motor- and somatosensory-evoked potential monitoring, cerebrospinal fluid drainage, and prevention of hypotension can reduce the incidence of spinal cord ischemia and improve the neurologic outcome of patients undergoing endovascular thoracic or thoracoabdominal aortic repair.

Evaluation of thrombogenicity by indium-111 platelet scintigraphy in endografting for abdominal aortic aneurysms

Obstruction of the endograft limb by thrombosis has often been reported and may cause fatal complications such as leg necrosis or myonephropathic metabolic syndrome. The purpose of this study was to evaluate endograft antithrombogenicity by indium-111 platelet scintigraphy. Seventeen patients with abdominal aortic aneurysms were treated by endografting. Thirteen patients were treated with conventional open surgery using an artificial graft. The endograft was constructed from a self-expanding Z-shaped stent and woven polyester fabric. Autologous platelets labeled with indium-111 were injected at 2 weeks postoperatively. At 24 hours and 72 hours postinjection, the ratio of scintillation count of the endograft or graft to that of the native artery was calculated to assess platelet deposition. The normalization ratio was calculated as follows: (scintillation count per pixel of endograft or graft/circumference)/(scintillation count per pixel of the native femoral artery). Platelet factor 4 and beta-thromboglobulin were measured to evaluate the systemic platelets activity at 2 weeks postoperatively. There was no significant difference in platelet counts or labeling efficiency between the groups. The ratio was significantly higher in the endografting group than in the open surgery group at 72 hours postinjection (2.5-0.7 vs 3.9-1.1, P<.001). There was no significant difference in platelet factor 4 and beta-thromboglobulin between the groups. Although there was no difference in systemic platelet activity, endografting was associated with lower antithrombogenicity. It remains unclear whether lower antithrombogenicity causes thromboembolism as a complication of the procedure. The authors recommend the administration of antiplatelet drugs to prevent endograft obstruction in patients with very narrow iliac arteries.

Coagulation Disorders and Blood Product Use in Patients Undergoing Thoracoabdominal Aortic Aneurysm Repair

Repair of thoracoabdominal aortic aneurysms (TAAA) is associated with major blood loss, often exceeding the patient's intravascular volume, and complex intraoperative and postoperative coagulopathies necessitating large-volume transfusion of blood products. Abnormalities sufficient to cause thrombocytopenia or clinically important prolongation of clotting parameters are rarely present before surgery in elective aneurysms but are more common with ruptured aneurysms. The finding of intraoperative and postoperative deficiencies of clotting factors, along with thrombin generation and activation of the thrombolytic system, is reflective of massive blood losses, visceral ischemia, and massive transfusions. An aggressive strategy of transfusion of blood products is critical to the prevention of clinically significant coagulopathy during surgery. Adjuncts to reduce blood losses and blood product use include low-dose aprotinin or epsilon -aminocaproic acid, intraoperative blood salvaging, and acute normovolemic hemodilution. In TAAA repair, an average blood loss of 5000 to 6000 mL and average transfusion of allogeneic blood products of 50 to 60 U are to be anticipated.