Percutaneous mechanical thrombectomy in the treatment of acute iliofemoral deep vein thrombosis: a systematic review.

BACKGROUND: Conventional treatment of deep vein thrombosis (DVT) of the lower extremities by anticoagulation alone has been proven to be insufficient to prevent recurrence and post-thrombotic syndrome (PTS). Early restoration of venous patency and preservation of valvular function by endovascular surgery has been advocated. The aim of this study was to review the efficacy and safety of percutaneous mechanical thrombectomy (PMT) against catheter-directed thrombolysis (CDT) in the treatment of acute iliofemoral DVT. METHODS: Three hundred sixty-nine articles were identified through screening of the PubMed, EMBASE, and Cochrane databases from January 2006 to December 2016. RESULTS: Fifteen retrospective studies and one prospective registry, totalling 1170 patients, were recruited for qualitative synthesis. The venous patency rate ranged from 75% to 100% with mean follow-up of 12.3 months. The rates of PTS and recurrent DVT were less than 17% and 15%, respectively. The overall mortality rate was 0.26%. Compared with CDT, PMT was shown to reduce PTS at 1 year (Villalta score: 2.1 ± 3.0 in the PMT group and 5.1 ± 4.1 in the CDT group, P=0.03) and bleeding complications (packed cells transfused: 0.2 ± 0.3 units in the pharmacomechanical thrombectomy group and 1.2 ± 0.7 units in the CDT group, P<0.05). CONCLUSION: Percutaneous mechanical thrombectomy is a safe and effective treatment for acute iliofemoral DVT in terms of restoration of venous patency, prevention of DVT recurrence, and PTS. Compared with CDT alone, PMT offers a lower risk of PTS and bleeding complications.

Haemodynamic Variations of Flow to Renal Arteries in Custom-Made and Pivot Branch Fenestrated Endografting.

OBJECTIVE: This study aimed to investigate variation of blood flow to renal arteries in custom-made and pivot branch (p-branch) fenestrated endografting, using a computational fluid dynamics (CFD) technique. METHODS: Idealised models of custom-made and p-branch fenestrated grafting were constructed on a basis of a 26 mm stent graft. The custom-made fenestration was designed with a 6 mm diameter, while the 5 mm depth renal p-branch was created with a 6 mm inner and 15 mm outer fenestration. Two configurations (option A and option B) were constructed with different locations of p-branches. Option A had both renal p-branches at the same level, whereas option B contained two staggered p-branches at lower positions. The longitudinal stent orientation in both custom-made and p-branch models was represented by a takeoff angle (ToA) between the renal stent and distal stent graft centreline, varying from 55° to 125°. Computational simulations were performed with realistic boundary conditions governing the blood flow. RESULTS: In both custom-made and p-branch fenestrated models, the flow rate and wall shear stress (WSS) were generally higher and recirculation zones were smaller when the renal stent faced caudally. In custom-made models, the highest flow rate (0.390 L/min) was detected at 70° ToA and maximum WSS on vessel segment (16.8 Pa) was attained at 55° ToA. In p-branch models, option A and option B displayed no haemodynamic differences when having the same ToA. The highest flow rate (0.378 L/min) and maximum WSS on vessel segment (16.7 Pa) were both calculated at 55° ToA. The largest and smallest recirculation zones occurred at 90° and 55° ToA respectively in both custom-made and p-branch models. Custom-made fenestrated models exhibited consistently higher flow rate and shear stress and smaller recirculation zones in renal arteries than p-branch models at the same ToA. CONCLUSIONS: Navigating the renal stents towards caudal orientation can achieve better haemodynamic outcomes in both fenestrated devices. Custom-made fenestrated stent grafts are the preferred choice for elective patients. Further clinical evidence is required to validate the computational simulations.

Novel endovascular procedures and new developments in aortic surgery.

Endovascular repair has evolved to become a viable mainstream treatment for aortic pathology in both acute and elective settings. As technology advanced, traditional anatomical barriers were progressively tackled using new devices and novel procedures, and there are now multiple options available to the vascular surgeon. In the abdominal aorta, advances in endovascular aneurysm repair have been in the treatment of hostile aortic necks using new sealing concepts and ancillary procedures, and in branch preservation using fenestrations and snorkels. Access challenges have been met with a percutaneous approach and low-profile devices, and standard protocols have improved mortality for ruptured aneurysms. In the thoracic aorta, more invasive hybrid procedures have given way gradually to branched endografts. Particular challenges to the anaesthetist include blood pressure control and the prevention of stroke and paraplegia. Current focus in the thoracic aorta is in treating aortic arch pathology and in optimal management of acute and chronic dissections. This review describes the latest trends in the endovascular treatment of aortic diseases and examines the current evidence for different modalities of management.

Aortic arch pathologies - incidence and natural history.

Endovascular interventions have made significant progress and are moving towards treating diseases of the aortic arch. Aortic arch pathologies incur substantial morbidity as well as short and long-term mortality but the progression is not well understood. This article reviews the current evidence on the natural history of aortic arch aneurysms and acute aortic syndromes, including penetrating ulcers, intramural hematomas, acute and chronic type B dissections. Risk factors for disease progression and mortality are also identified with special reference to vascular surgeons.

Persistent Intraluminal Pressure After Endovascular Stent Grafting for Type B Aortic Dissection.

OBJECTIVES: Despite technically successful thoracic endovascular stent graft repair (TEVAR) in patients with Stanford Type B aortic dissection (TBAD), long-term follow up studies have shown that the false lumen may continue to dilate. The aim of this study was to analyze the possible mechanisms leading to such changes from a hemodynamic perspective. METHODS: Twenty-eight ex vivo fresh porcine TBAD models (Mo A: 10; Model B: 12; Model C: 6) were established to simulate three clinical situations: Model A with patent false lumen (pre-TEVAR); Model B with distal re-entry only (post-TEVAR), and Model C with thrombus filling in the false lumen and a distal re-entry (chronic stage of post-TEVAR). Synchronous pressure waveforms were taken from both the true and the false lumen. True lumen and false lumen pressure differences were calculated for each model as four indices: systolic index (SI), diastolic index (DI), mean pressure index (MPI) and area under curve index (AUCI). These indices were compared between the three models. RESULTS: False lumen pressure and corresponding pressure-accumulating effects were significantly higher in Model A than in Model C: SI (99.9% vs. 189.4%; p < .001); MPI and AUCI (99.5% vs. 128.2%; 99.5% vs. 128%; p < .001). The SI, MPI, and AUCI were significantly higher in Model B compared with Model C. The differences between the four indices were not significant between Model A and B. The false lumen area under curve (AUC) in Model C was merely lowered by 20% compared with its true lumen (67.5 mmHg vs. 85.2 mmHg). CONCLUSION: The false lumen pressure remained unchanged in the non-thrombosed segment with patent blood flow after the primary entry tear sealed. Intraluminal pressure reduction in the thrombosed false lumen was significant. However, nearly 80% of the pressure remained in the thrombosed false lumen. If this high intra-thrombus pressure persists, it may contribute to delayed aneurysmal formation after endovascular treatment.

Ex-vivo haemodynamic models for the study of Stanford type B aortic dissection in isolated porcine aorta.

OBJECTIVES: The aim of this study is to present novel ex-vivo models in the study of complex haemodynamical changes in Stanford type B aortic dissection (TBAD). MATERIALS AND METHODS: Fifteen fresh porcine aortas were harvested and preserved with 4 °C saline. Ex-vivo models were developed to simulate TBAD in three different situations: model A with patent false lumen, model B with distal re-entry only and model C with proximal primary entry only. These models were connected to standardised pulsatile pumps and the pressure waveforms were monitored and compared. The aortas were scanned with ultrasonography and subjected to post-experiment autopsy. RESULTS: The three different models were successfully created (n = 13). Pulsatile flow testing was successful and the shapes of the pressure waveforms were similar to those taken from human aorta. Post-testing gross examination confirmed the success of modelling. CONCLUSION: Porcine aortas may prove to be useful ex-vivo models in the study of aortic dissection haemodynamics. These models are reproducible and may be used in the study of complex haemodynamic forces during the development and propagation of TBAD. Our three porcine models give a potential possibility in helping clinicians isolate and analyse complex haemodynamical factors in the development, propagation and prognosis of TBAD.

Annexin A1 expression in atherosclerotic carotid plaques and its relationship with plaque characteristics.

OBJECTIVE: Annexin A1, a calcium and phospholipid-binding protein, is an important endogenous modulator of inflammation. Whether this regulatory role extends to atherosclerosis is unknown. The aim of this study is to investigate the genetic and protein expression of Annexin A1 in carotid endarterectomy specimens from patients with significant carotid stenosis. MATERIALS AND METHODS: The echogenicity of atherosclerotic plaques was determined by ultrasound prior to carotid endarterectomy (CEA) in 34 consecutively recruited patients with carotid stenosis exceeding 70%. The Annexin A1 messenger RNA and protein expression of the corresponding plaques obtained from those patients were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and the immunohistochemical method respectively. Results were analyzed with respect to plaque characteristics and symptomatic disease. RESULTS: There were 25 males and 9 females, with a mean age of 68.8. Ten patients were asymptomatic. The symptomatic patients' plaques were more echolucent (mean grey scale median (GSM) of 103) than those of asymptomatic patients (mean GSM = 126, p = 0.022). The Annexin A1 protein was constitutively expressed in all plaques, and Annexin A1 gene expression was statistically higher in patients with asymptomatic disease compared with those with neurological symptoms (87 ± 4% vs. 42 ± 6.2%; p < 0.001, unpaired t-test). The GSM score was positively correlated with Annexin A1 levels in patients with high-grade carotid artery stenosis (r = 0.501, p = 0.009). CONCLUSIONS: This is the first study to suggest that high Annexin A1 expression may have a stabilising effect in asymptomatic patients with less echolucent atherosclerotic plaques. Since atherosclerosis is an inflammatory process, we further postulate that Annexin A1 may play an essential role in preventing plaque complications or disease progression.

A study of surgeons' postural muscle activity during open, laparoscopic, and endovascular surgery.

BACKGROUND: Different surgical procedures impose different physical demands on surgeons and high prevalence rates of neck and shoulder pain have been reported among general surgeons. Past research has examined electromyography in surgeons mainly during simulated conditions of laparoscopic and open surgery but not during real-time operations and not for long durations. The present study compares the neck-shoulder muscle activities in three types of surgery and between different surgeons. The relationships of postural muscle activities to musculoskeletal symptoms and personal factors also are examined. METHODS: Twenty-five surgeons participated in the study (23 men). Surface electromyography (EMG) was recorded in the bilateral cervical erector spinae, upper trapezius, and anterior deltoid muscles during three types of surgical procedures: open, laparoscopic, and endovascular. In each procedure, EMG data were captured for 30 min to more than 1 h. The surgeons were asked to rate any musculoskeletal symptoms before and after surgery. RESULTS: The present study showed significantly higher muscle activities in the cervical erector spinae and upper trapezius muscles in open surgery compared with endovascular and laparoscopic procedures. Muscle activities were fairly similar between endovascular and laparoscopic surgery. The upper trapezius usually has an important role in stabilizing both the neck and upper limb posture, and this muscle also recorded higher activities in open compared with laparoscopic and endovascular surgeries. Surgeons reported similar degrees of musculoskeletal symptoms in open and laparoscopic surgeries, which were higher than endovascular surgery. CONCLUSIONS: The present study showed that open surgery imposed significantly greater physical demands on the neck muscles compared with endovascular and laparoscopic surgeries. This may be due to the lighter manual task demands of these minimally invasive surgeries compared with open procedures, which generally required more dynamic movements and more forceful exertions.

Detection of C. pneumoniae by polymerase chain reaction-enzyme immunoassay in abdominal aortic aneurysm walls and its association with rupture.

OBJECTIVE: Serological studies have suggested that one of the risk factors for aneurysm development is C. pneumoniae infection. The purpose of this study was to evaluate whether there is an association between the presence of C. pneumoniae DNA in aneurysms and ruptured abdominal aortic aneurysms. METHODS: Aortic walls were collected consecutively from 30 patients with intact AAA, 16 patients with ruptured AAA and 19 healthy organ donors (control). Purified DNAs from all aortas were analyzed for the presence of C. pneumoniae DNA in parallel by polymerase chain reaction-enzyme immunoassay (PCR-EIA) and agarose gel electrophoresis. PCR-EIA has a high sensitivity in detecting low DNA copy number in clinical atherosclerotic samples. RESULTS: C. pneumoniae DNA was detected more frequently in patients with aneurysms, particular with ruptured aneurysms. The incidence of positive C. pneumoniae DNA was 73.3% in intact AAA and 10.5% in control aortas, with the highest frequency in ruptured AAA (100%) (p < 0.05). CONCLUSION: Giving the high specificity and sensitivity of PCR-EIA, these findings support the association of C. pneumoniae in the pathogenesis of aneurysm development, growth and rupture.

Laparoscopic transperitoneal clipping of the inferior mesenteric artery for the management of type II endoleak after endovascular repair of an aneurysm.

We report the case of a high risk patient with an abdominal infrarenal aortic aneurysm (AAA) who was treated by endovascular technique and the subsequent management of a type II endoleak by the laparoscopic approach. In this case, a 74-year-old woman with a 6-cm infrarenal AAA underwent endovascular repair using a bifurcated stent-graft device. Surveillance CT scan showed a persistent type II endoleak at 1 week and 3 months after the operation. Angiography confirmed retrograde flow from the inferior mesenteric artery (IMA). Attempted transarterial embolization of the IMA via the superior mesenteric artery was not successful. Laparoscopic transperitoneal IMA clipping was performed. Subsequent aortic duplex scan and CT scan confirmed complete elimination of the type II endoleak. We conclude that a combination of endovascular and laparoscopic procedures can be used to manage AAA successfully.

Epidemiology of venous thromboembolism in a Chinese population.

BACKGROUND: Deep vein thrombosis (DVT) is uncommon in Asians and routine thromboprophylaxis for surgery is controversial. Despite recent reports of higher incidences in some Asian countries, population-based data are lacking. METHODS: Information from 2000 to 2001 was retrieved from a centralized computer public healthcare database serving an ethnic Chinese population of 6.7 million. The incidence, demographics and hospital mortality rates of DVT and pulmonary embolism (PE) were obtained, and analysed for different surgical categories. RESULTS: The overall annual incidences of DVT and PE were 17.1 and 3.9 per 100000 population respectively. Venous thromboembolic disease was more common with increasing age in both sexes. The annual age-specific incidences of DVT and PE were 81.1 and 18.6 per 100000 for those aged 65 years and over. Hospital mortality rates associated with DVT and PE were 7.3 and 23.8 per cent respectively. Among 120940 surgical operations a year, the mean incidence of postoperative DVT and PE was only 0.13 and 0.04 per cent respectively. No high-risk surgical group was identified. CONCLUSION: Venous thromboembolism is not as common in Chinese as in Caucasians, but it is certainly not rare. The majority of DVTs and PEs, however, were not associated with surgery, so routine thromboprophylaxis may not be required.

Clinical outcomes and changes in venous hemodynamics after subfascial endoscopic perforating vein surgery.

BACKGROUND: We evaluated the clinical results of subfascial endoscopic perforating vein surgery (SEPS) in patients with severe chronic venous insufficiency (CVI) (clinical class 4-6) and assessed the hemodynamic changes associated with SEPS using air plethysmography (APG). METHODS: Forty-five patients with severe CVI who had undergone SEPS were evaluated. Clinical score and venous hemodynamics, as measured by APG before operation and at 1 month and 1 year after operation, were compared using the Wilcoxon signed rank test. Patient satisfaction (on a visual analogue scale of 0 to 100%) was also assessed. RESULTS: There were 29 men and 16 women; their mean age was 60 years (range, 37-83). Thirty-five patients (78%) had active venous ulcers; the ulcers' mean size was 7.8 +/- 11.9 cm2 and the mean duration of ulceration was 9 +/- 10 months. There were no hospital deaths. Postoperative complications were uncommon (one groin wound infection and one case of thrombophlebitis). At a mean follow-up of 15 +/- 9 months, 34 ulcers (97%) had healed. The cumulative ulcer healing was 82% at 3 months. There were five recurrent ulcers (15%). Significant improvement was seen in the clinical scores (10 +/- 3 before operation, 6 +/- 4 at 1 month, and 4 +/- 3 at 1 year after operation). The venous filling index was also significantly improved after operation; this improvement was maintained at 1-year follow-up (7.36 +/- 6.23 ml/sec before operation, 3.63 +/- 3.90 ml/sec at 1 month, and 3.14 +/- 2.06 ml/sec at 1 year). The degree of patient satisfaction was also remarkable, with 74 +/- 17% and 90 +/- 12% satisfaction at 1-month and 1-year follow-up, respectively. CONCLUSIONS: SEPS is a safe and effective treatment for patients with severe CVI. It leads to hemodynamic improvement, with rapid ulcer healing, and it is associated with a high degree of patient satisfaction.

Carotid stenting for irradiation-associated carotid stenosis 3 years after previous carotid endarterectomy.

Extracranial carotid stenosis is a known complication of external irradiation to the head and neck region. We report on a patient with previous carotid endarterectomy for irradiation-associated carotid stenosis. This patient developed symptomatic carotid stenosis over the ipsilateral common carotid artery proximal to the previous endarterectomy site 3 years later, and was successfully treated with carotid angioplasty and stenting. This case illustrates the importance of Duplex scan surveillance after carotid endarterectomy for patients with irradiation-associated carotid stenosis. The complimentary role of carotid endarterectomy and carotid angioplasty for managing such a patient is highlighted.

Treatment of a ruptured iliac aneurysm with an endoluminal stent graft.

The management of a 79-year-old man presenting with a ruptured common iliac aneurysm is described. The patient had multiple medical problems including hypertension, ischaemic heart disease, and atrial fibrillation, as well as a left hemispheric stroke 5 years previously. Traditional open surgery was judged unsuitable in this case because of the predicted poor outcome. The patient was subsequently treated successfully with endoluminal stent grafting.

Diagnosing deep vein thrombosis in the lower extremity: correlation of clinical and duplex scan findings.

OBJECTIVE: To identify factors that predict a positive duplex scan examination result in patients with suspected deep vein thrombosis of the lower extremity. DESIGN: Retrospective study. SETTING: Vascular laboratory in a university teaching hospital. PATIENTS AND METHODS: The results of 345 lower extremity duplex venous scans performed between August 1994 and November 1998 were reviewed. All patients were in-patients referred from different specialties due to clinical suspicion of lower extremity deep vein thrombosis. Positive duplex scans were correlated with patients' demographic data (sex, age), medical history (history of malignancy, deep vein thrombosis, and pulmonary embolism) and clinical features (leg swelling, venous insufficiency, calf pain, and leg ulcer). Univariate analysis was performed using the Chi squared test. RESULTS: A total of 345 scans were performed for 313 patients. The mean age was 55 years (range, 19-92 years). Sixty-three patients (49 male, 14 female) had a positive scan, giving a yield of 18.3%. Four factors had a significant association with a positive scan: male sex (P=0.0102), history of malignancy (P=0.0040), history of deep vein thrombosis (P=0.0001), and history of pulmonary embolism (P=0.0265). CONCLUSIONS: Common presenting clinical features do not predict the result of ultrasonographic investigation for deep vein thrombosis. The chance of having a positive scan is significantly higher in male patients and those with a history of malignancy, deep vein thrombosis, or pulmonary embolism.