Yiu-Che Chan

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.

Para-Aortic Lymphoma Simulating Mycotic Abdominal Aortic Aneurysm

A 70-year-old man presented with 6 months’ history of progressively severe backache and left frank pain. Past history was significant for an aortobifemoral Dacron bypass graft performed 11 years ago for intermittent claudication attributable to aortoiliac occlusive disease. A contrast computed tomography (CT) scan showed a slight irregularity around the pararenal aorta without other abnormalities. Because of persistent symptoms, a positive emission tomography-CT scan was performed that showed a large pseudoaneurysm measuring 6.1×3.8×2.8 cm arising from the juxtarenal aorta above the previous aortic graft (Figure 1) with an associated retroperitoneal soft tissue mass encasing the left renal artery with a standardized uptake value of 22.5 (Figure 2). At this stage, the differential diagnosis was of juxtarenal aortic mycotic aneurysm or an anastomotic pseudoaneurysm with contained rupture, or retroperitoneal tumor with aortic invasion. The patient was referred to our tertiary vascular center for further management. Figure 1. Computed tomography scan …

Endovascular Management of Stanford Type A (Ascending) Aortic Dissection

With advances in endovascular technology and stent graft improvement over the past decade, it might be only a matter of time before pure endovascular management of ascending aortic dissection becomes a viable option. Successful endovascular stent graft repair of thoracic aortic dissection involving the ascending aorta and aortic arch requires a sufficient proximal landing zone with a portion of healthy aorta for the stent graft to fix and seal, while preserving aortic valvular competence, coronary and supra-aortic perfusion.

Mid- and long-term outcome of patients with permanent inferior vena cava filters: a single center review.

BACKGROUND Inferior vena cava (IVC) filters are used to prevent pulmonary embolism (PE), especially in patients with active contraindication to systemic anticoagulation. The aim of this study is to examine the outcomes of patients who received permanent IVC filters at our institution. METHODS This is a single-center retrospective observational study with review of a prospectively collected database for patients who had permanent IVC filters. Patient demographics, indications of filter placement, postprocedure clinical outcome and complications, as well as use of anticoagulant therapy were documented. Chi-squared test was used to test for statistically significant differences (IBM SPSS version 21; IBM Corp., Armonk, NY), while survival was calculated using Kaplan-Meier survival curves analysis. RESULTS Between February 1998 and December 2013, a total of 109 patients with a median age of 65 (47 men, range 19-97) years had IVC filters inserted at our institution. All of them had documented venous thromboembolism (VTE) before filter placement: 99 (90.8%) had lower extremity deep vein thrombosis (DVT) (including 34 iliac, 65 infrainguinal), 9 (8.3%) had massive PE without evidence of lower limb DVT, and 1 (0.9%) had isolated IVC thrombosis. Forty-seven (43.1%) patients had PE before filter insertion. There were 2 serious procedure-related complications: one access site thrombosis and one right ventricular perforation. With a mean follow-up of 36 ± 33 months, no patient had further symptomatic PE or paradoxical embolism. There were a total of 54 (49.5%) deaths, with a 30-day mortality of 8.3%; none of them was device or procedure related. Among the 92 patients followed up, 27 (29.3%) had further VTE-either DVT in the index or the contralateral lower limb (20 patients, 21.7%), or thrombus inside the filter or the IVC (14 patients, 15.2%). Forty-one (44.6%) patients reported post-thrombotic syndrome (PTS) symptoms. Anticoagulant therapy was given to 39 (42.4%) and 55 (59.8%) patients in the periprocedural period and at any time during the study period, respectively. It did not reduce the rate of postfilter VTE or PTS in both instances. None of the filters in this series was retrieved. CONCLUSIONS This observational study showed that IVC filters were effective in the prevention of PE, although symptomatic postfilter VTE and PTS were common, leading to significant morbidity. Patients who received permanent filters have high mortality on follow-up; however, none were procedure or device related.

Endovascular infrarenal aneurysm repair in patients with horseshoe kidneys: case series and literature review

Horseshoe kidney may cause technical and access problems during open aortic aneurysm repair. The aim of this study is to report two cases from our institution and to review the worlds literature on successful endovascular infrarenal aneurysm repair in patients with horseshoe kidneys. A retrospective review of a prospectively entered departmental computerized database was performed for the two patients from our institution. Articles were searched electronically from PubMed and Medline, using the terms ‘horseshoe kidney’ and ‘aneurysm’. Endovascular cases were reviewed from the worlds literature. In addition to the two patients from our institution, there were 19 patients with infrarenal aneurysms and horseshoe kidneys in published literature who underwent successful endovascular aneurysm repair. The occlusion of lower-pole or accessory renal arteries does not seem to cause significant endoleak or renal impairment in the long run. In conclusion, our experience and current literature seem to suggest that endovascular repair of infrarenal aortic aneurysms for patients with horseshoe kidneys is safe. Renal impairment will depend on the area of kidney perfused by the accessory renal arteries. The endovascular treatment option is less invasive than open repair, and circumvents the problem of difficult exposure, especially in those patients with significant co-morbidity.

Management of mycotic femoral artery aneurysm with two resistant organisms

We report the management of a case of thigh abscess with ruptured left superficial femoral artery mycotic aneurysm in a 91-year-old woman with significant comorbidity. The abscess culture grew Escherichia coli and Acinetobacter baumannii. Vascular reconstruction was not performed because the foot was viable with a heavily contaminated wound. The thigh wound healed with the help of vacuum-assisted closure. This is the first report of a ruptured mycotic aneurysm of the superficial femoral artery associated with Escherichia coli and Acinetobacter baumannii infection. This case demonstrates that resection of a mycotic aneurysm without vascular continuity is feasible, especially in frail patients.

Custom-made fenestrated stent grafts to preserve accessory renal arteries in patients with abdominal aortic aneurysms.

Abstract Accessory renal arteries are common and may contribute significantly to renal perfusion. With the current endovascular design and technology, it is possible to preserve accessory renal arteries during endovascular aneurysm repair (EVAR). We report two patients with custom-made EVAR devices to preserve accessory renal arteries with good mid-and long-term clinical and radiological results. Conventional EVAR would have occluded their origins. As a result of customized fenestrations in commercially available stentgrafts, the patency of large accessory renal arteries can be maintained, whilst securing a proximal seal.

Successful endovascular management of giant splenic artery aneurysms

Giant pseudoaneurysms of the splenic artery, with a diameter of 5 cm or more, are rare surgical emergencies, and conventional open surgery usually involves splenectomy. The aim of this study is to report two cases from our institution and to review the worlds literature on successful endovascular treatment of patients with giant splenic artery pseudoaneurysms. A retrospective review of a prospectively entered departmental computerized database was performed for the two patients from our institution. Articles were searched electronically from PubMed and Medline, using the terms ‘giant splenic artery’, ‘endovascular’ and ‘embolization’; and relevant cases were reviewed from the worlds literature. We hereby report two patients with giant splenic artery pseudoaneurysms who were treated successfully with endovascular procedures. In addition to the two patients from our institution, there were five patients with giant splenic artery pseudoaneurysms in the published literature who underwent successful endovascular management. The first patient of our series had the largest pseudoaneursym size of 7.2 × 8.1 cm, which is the largest documented pseudoaneursym in the current literature. We report two cases of giant splenic artery pseudoaneurysm with one being the largest pseudoaneurysm treated with endovascular technique in the current literature. Endovascular coil embolization of main trunk of splenic artery is less invasive than open surgical treatment for giant splenic artery pseudoaneurysm, and circumvents the problem of difficult exposure, especially in those patients with significant co-morbidity.

Surgical management of carotid body tumor – Is Shamblin classification sufficient to predict surgical outcome?

Background The study aims to conduct a review of the surgical management of carotid body tumor. Methods Consecutive patients with CBT who received surgical interventions from January 1994 to January 2014 at our institution were reviewed. Clinical, operative, pathological and follow up information were reported. Results Twenty patients (four males; median age was 36) with 21 CBT operations were recorded during the period. One patient undertook sequential operations for bilateral CBTs. Patients had 19 neck mass, 1 incidental finding and 1 facial nerve palsy. Six CBTs (28.6%) were Shamblin class I, ten (47.6%) were class II and five (23.8%) were class III. Nine CBTs had preoperative conjunctive embolization. Two operations required internal carotid artery resection and reconstruction. Four patients received subtotal resections, while 17 achieved complete resection. Complications included two major strokes, three hoarse voice and two Horner’s syndrome. Shamblin class was significant predictor of operative time, blood loss, and whether complete resection accomplished, but could not predict postoperative complication. With median follow up period of 94 months, there was no tumor recurrence found in those had complete resection. Conclusions This small cohort showed that Shamblin class was significant in predicting technical difficulties but could not predict occurrence of complications.

Mycotic Aneurysm of the Common Carotid Artery as a Presenting Symptom for Early Colorectal Malignancy

Mycotic carotid aneurysms are rare vascular conditions that are associated with high mortality if left untreated. We present a gentleman who had a progressively enlarging tender pulsatile swelling on the right side of neck. Emergency computed tomography scan showed a large mycotic aneurysm arising from the right common carotid artery, and he underwent emergency open exploration with interposition bypass graft. Bacteroides fragilis species, which signified gastrointestinal-related sepsis, was isolated from the thrombus culture. Subsequently search of systemic septic source showed an early rectal adenocarcinoma. This is the first case in the worlds literature of a patient who had B. fragilis mycotic carotid aneurysm as a presenting complaint of his occult rectal malignancy.