Pei Ho

Aortic Aneurysm Morphology in Asians: Features Affecting Stent-Graft Application and Design:

Purpose: To determine the morphological features of abdominal aortic aneurysms (AAA) in an Asian cohort in order to identify unique features relevant to stent-graft planning and application. Methods: Spiral computed tomography (CT) and angiographic assessment of AAA morphology was performed on 65 ethnic Chinese (58 men; mean age 74 years, range 50–87) who underwent endovascular AAA repair. Morphological parameters were compared with published data from American and European patients. The eligibility and potential concerns referable to 4 current stent-graft designs were addressed. Results: Both common iliac arteries (CIA) measured significantly shorter in Asians, particularly on the right side. The mean RCIA and LCIA lengths were 29.9 mm and 34.2 mm, respectively (25.7 and 34.1 mm for CIAs <20 mm in diameter), compared to >50-mm in Caucasians (p<0.001). The distance between the lowest renal artery and the CIA bifurcation averaged 20 mm shorter in Asians: 148 mm on the right side and 153 mm for the left. The CIAs were also wider, averaging 20.2 mm for the right and 17.9 mm for the left. Other linear measurements did not show a population difference. The AAAs in this series were slightly larger (p<0.001), with a shorter neck (mean 23 mm, p<0.001). No correlation was found between the morphological parameters and body build. Internal iliac artery coverage with or without embolization was necessary in 51% of endovascular repairs due to short or aneurysmal CIAs. Conclusions: These differences in AAA morphology pose unique challenges for endovascular repair in Asians. Preoperative angiography is more often necessary. The need for an accurate landing in a short CIA and insufficient length for maneuvering placed constraints on 2-piece graft designs with long main body lengths. A 3-piece endograft with wider aortic and iliac diameters is currently the most attractive option.

Supra-aortic hybrid endovascular procedures for complex thoracic aortic disease : Single center early to midterm results

BACKGROUND Hybrid technique with open surgical supra-aortic extra-anatomical bypasses (to provide a suitable proximal landing zone) and simultaneous or staged thoracic endovascular stent grafting is less invasive than open surgery in the treatment of complex aortic arch pathology. The aim of this study is to report our hybrid experience. METHODS Retrospective review of prospectively collected computerized database. All patients had regular clinical and radiological computed tomography follow-up. RESULTS Sixteen patients (13 males and 3 females) with mean age of 64.8 (range 51-79) were treated with hybrid techniques between May 2005 and September 2007. There were nine elective, two urgent (within 2 weeks of presentation), and five emergency cases. Thirteen patients had arch or proximal descending thoracic aortic aneurysms, and six patients had aortic dissections. All extra-anatomical bypasses were performed simultaneously with stent grafts, with mean operating time of 331.2 (range 195-540) minutes. Eight patients had right to left carotid-carotid cross-over graft, five had bifurcating grafts from ascending aorta to innominate and left carotid artery, two had left carotid to left subclavian artery, and one had left carotid to aberrant right subclavian bypass graft. All patients had Cook Zenith thoracic stent grafts. Deployment success was 100%, with no endoleak on completion angiogram. There was no mortality. Three patients had postoperative nondebilitating stroke and no paraplegia. The mean follow-up was 14 (range 1-27) months. One reintervention was required, and two patients had type II endoleak treated conservatively. CONCLUSION Supra-aortic hybrid procedures in treating aortic arch pathology are safe and effective, and early- to midterm results are encouraging.

Carotid Stenting for Radiation-Induced Extracranial Carotid Artery Occlusive Disease: Efficacy and Midterm Outcomes

PURPOSE To investigate the immediate and midterm results of carotid stenting for severe radiation-induced extracranial carotid artery disease. METHODS Between April 1998 and May 2002, 16 patients (15 men; mean age 64 +/- 8 years, range 48-72) presented with 18 severe radiation-induced carotid stenoses in the internal carotid artery (n=3), common carotid artery (n=7), and both vessels (n=8). Thirteen (76%) patients were symptomatic; the mean degree of carotid stenosis was 85% +/- 10% (range 70%-95%). An independent neurological specialist assessed perioperative neurological complications before and after treatment. The patients were followed prospectively for at least 12 months by clinical examination and serial duplex ultrasound scanning. Restenosis was defined as a diameter reduction >50%. RESULTS Of 18 stent procedures attempted (2 staged), 1 was abandoned owing to failure to pass the guidewire across a tight lesion (94% technical success by intent to treat). In the 17 successfully completed procedures, 17 Wallstents and 4 SMART stents were deployed with satisfactory anatomical results. One postoperative stroke occurred as a result of thromboembolism to the ipsilateral middle cerebral artery and led to hospital death (5.9% combined stroke and death rate). One transient ischemic attack occurred (11.6% neurological event rate). With a median 30-month follow-up (range 5-55), 3 (17.6%) recurrent stenoses (>50%) were detected on duplex scan; 1 repeat angioplasty was performed. No new neurological event has been detected. CONCLUSIONS Carotid stenting may be performed in patients with irradiation-induced carotid stenosis with acceptable risks and midterm durability.

A computational fluid dynamic study of stent graft remodeling after endovascular repair of thoracic aortic dissections

OBJECTIVES Significant stent graft remodeling commonly occurs after endovascular repair of thoracic aortic dissections because of continuing expansion of the true lumen. A suboptimal proximal landing zone, minimal oversizing, and lack of a healthy distal attachment site are unique factors affecting long-term stent graft stability. We used computational fluid dynamic techniques to analyze the biomechanical factors associated with stent graft remodeling in these patients. PATIENTS AND METHODS A series of computational fluid dynamic models were constructed to investigate the biomechanical factors affecting the drag force on a thoracic stent graft. The resultant drag force as a net change of fluid momentum was calculated on the basis of varying three-dimensional geometry and deployment positions. A series of 12 patients with type B aortic dissections treated by thoracic stent graft and followed up for more than 12 months were then studied. Computed tomography transaxial images of each patient shortly after stent graft deployment and on subsequent follow-up were used to generate three-dimensional geometric models that were then fitted with a surface mesh. Computational fluid dynamic simulations were then performed on each stent graft model according to its geometric parameters to determine the actual change in drag force experienced by the stent graft as it remodels over time. RESULTS The drag force on the stent graft model increases linearly with its internal diameter and becomes highest when the deployment position is closer to the proximal arch. Aortic curvature is not a significant factor. Serial computed tomography scans of patients showed an increase in mean inlet area from 1030 mm(2) to 1140 mm(2), and mean outlet area from 586 mm(2) to 884 mm(2) (increase of 11% and 58%, respectively; P = .05, .01). These increases are associated with a change in resultant drag force on the stent graft from 21.0 N to 24.8 N (mean increase, 19.5%; range, 0%-63.2%; P = .002). There is a positive relationship between increase in drag force and increase in stent-graft area. CONCLUSION The drag force on thoracic stent grafts is high. A significant change in stent-graft diameter occurs after endovascular repair for type B dissections, which is associated with an increase in hemodynamic drag force. These stent grafts may be subjected to a higher risk of distal migration, and continuing surveillance is mandatory.

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.

Vero cells, but not oviductal cells, increase the hatching frequency and total cell count of mouse blastocysts partly by changing energy substrate concentrations in culture medium

AbstractPurpose: To investigate the embryotrophic mechanisms of Vero and oviductal cells coculture. Methods: Mouse embryos were cultured in Chatot, Ziomek, and Bavister medium (CZB), in modified CZB media (MM) with nutrient concentrations adjusted to that found in conditioned media after different periods of Vero cells or oviductal cells culture, in reconstituted medium (RM) containing the purified >100-kDa components of Vero cell conditioned medium that had been reconstituted with CZB medium, and cocultured with Vero cells with an interposing membrane. Results: The blastulation rate was not different among embryos cultured in different Vero-cell–derived MMs. Nine-hour Vero-cell-derived MM significantly increased the total cell number and hatching frequency of the embryos. There was no difference in these parameters with oviductal-cell–derived MMs. The RM of Vero cells did not possess embryotrophic activity. The presence of a porous membrane between Vero cells and embryos did not affect the embryotrophic activity of coculture. Conclusions: Vero cells, but not oviductal cells, improved mouse embryo development partly by modifying the energy substrate concentration in culture medium.

Ten-Year Epidemiological Review of In-Hospital Patients with Marfan Syndrome

Marfan syndrome is a connective tissue disorder with a worldwide prevalence of 1 in 5,000, without any racial predilection. Major cardiovascular manifestations of Marfan disease often require surgical intervention. The aim of this study was to examine the demographics of patients with Marfan syndrome admitted to Hong Kong hospitals over a 10-year period from 1997 to 2006. We retrospectively reviewed the prospectively collected Hong Kong Health Authoritys Clinical Data Analysis and Reporting System and Clinical Medical System. Statistical analysis was performed using SPSS, version 15. A total of 525 patients with Marfan syndrome (310 male, 215 female) were included in this study. For males, mean age at first hospital admission was 19.8 years (range 0-78) and for females, 18.7 years (range 0-60). One hundred and twelve (21.3%) patients (56 male, 56 female) had documented aortoiliac aneurysms and/or dissection, with 74 (66.7%) cases involving the thoracic aorta. Forty-nine (9.3%) patients had major cardiac or aortoiliac operations, with an operative mortality of 5/49 (10.2%). Thirty-seven (7.0%) patients (23 male, 14 female) died during this period, with a mean age at death of 41.0 years (range 0-83) for males and 29.9 years (range 0-59) for females. The majority of these patients died of cardiovascular causes, with four aortic dissections, two ruptured aneurysms, seven with sudden collapse and cardiac arrest, and five with heart failure. In addition, there were other causes of mortality: five perioperative, one congenital, and four pulmonary causes, three with malignancy and one of stroke. The cause of death was unknown in five patients. Patients with aortoiliac diseases have a statistically significant higher mortality rate (p < 0.05). This population-based study shows that significant numbers of patients with Marfan syndrome are admitted to hospital per year, with a significant proportion requiring admissions at a young age. Life span in Marfan patients is markedly shortened, and aortoiliac disease is probably underdiagnosed. A standardized diagnostic and therapeutic follow-up program should be offered to these patients and their families.

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.

Blood loss and transfusion in elective abdominal aortic aneurysm surgery

Background:  Intraoperative blood loss and transfusion are known determinants of mortality and morbidity of elective abdominal aortic aneurysm (AAA) repair. The present study analysed the pattern of blood loss and transfusion and evaluated the risk factors of blood loss during open repair of infrarenal AAA.

Granulomatous appendicitis progressing to Crohn's disease with bleeding complication.

Granulomatous appendicitis can be idiopathic or due to a number of specific causes. Idiopathic granulomatous appendicitis is regarded as a separate disease entity and usually has a benign course. We report on a case of granulomatous appendicitis, which progressed to fulminant Crohns colitis shortly after appendicectomy. During the treatment with intravenous steroid, torrential gastrointestinal bleeding developed and emergency subtotal colectomy had to be performed. The clinical and histological features of the case are presented and the literature on granulomatous appendicitis reviewed.