Stephen W.K. Cheng

Irradiation-induced extracranial carotid stenosis in patients with head and neck malignancies

BACKGROUND Carotid stenosis is a recognized complication of external irradiation to the head and neck for malignancy. This study aim to investigate the pattern and prevalence of radiation induced carotid disease, and to identify risk factors associated with significant stenosis. METHODS In a comparative cross-sectional study, carotid arteries color flow duplex scan was performed on 240 patients who had received external irradiation to the head and neck area, with a mean interval of 72 months from radiotherapy. They consisted of 181 men and 59 women, with a mean age of 59 years. Fifteen patients had a history of cerebrovascular symptoms. RESULTS Internal carotid artery (ICA) stenosis of 70% or greater was detected in 29 arteries in 24 patients. Common carotid artery (CCA) disease of > or =70% was present in 13 arteries in 12 patients. Overall 28 patients had significant ICA/ CCA disease (11.7%). Patients with nasopharyngeal and laryngeal carcinoma had more cerebrovascular symptoms, and more frequent CCA stenosis. Significant ICA/CCA stenosis was associated with age, smoking, coronary heart disease, stroke, no head and neck surgery, time interval from radiotherapy, and the site of primary tumor. On logistic regression analysis age (>60 years), cerebrovascular symptoms, interval from irradiation (>5 years), and nasopharynx and larynx cancer were found to be independent significant (P<0.05) predictors of 70% or greater ICA/CCA stenosis. CONCLUSIONS Patients who had received radiotherapy to the head and neck have a high risk of developing significant carotid stenosis. Routine duplex ultrasound screening in these patients is indicated.

Pyloroplasty versus no drainage in gastric replacement of the esophagus

In a prospective randomized study of pyloroplasty versus no drainage, 200 patients (100 in each group) in whom the whole stomach was used for reconstruction following resection for esophageal carcinoma were studied. Only patients who underwent the Lewis-Tanner operation and who had a normal pylorus were included. There was no morbidity from the pyloroplasty procedure. Thirteen patients without drainage developed symptoms of gastric outlet obstruction, requiring prolonged post-operative parenteral nutrition, and reoperation was required in one patient. Four patients developed pulmonary complications associated with gastric distension, which resulted in fatal aspiration in two patients. Five patients had symptoms of outlet obstruction with eating at the time of their death. Mean and standard deviation of daily gastric aspirate was 161 +/- 88 mL in the pyloroplasty group and 233 +/- 142 mL for the control group (p = 0.23). Gastric emptying test showed mean T1/2 +/- standard deviation of 6.6 +/- 7.5 minutes in the pyloroplasty group and 24.3 +/- 31.5 minutes in the control group (p less than 0.001). More patients in the pyloroplasty group were able to tolerate a solid diet and at normal or increased amounts than were patients in the control group in the early postoperative weeks (p less than 0.01). In addition, control patients were found to have increased symptoms with meals, which were more frequent and of greater severity than symptoms in patients in the pyloroplasty group, even at 6 months after surgery (p less than 0.01). Therefore, we recommend a pyloroplasty for patients in whom the whole stomach is used for reconstruction after esophagectomy.

Epidemiology of venous thromboembolism in a Chinese population.

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.

Lipoprotein (a) and its Relationship to Risk Factors and Severity of Atherosclerotic Peripheral Vascular Disease

OBJECTIVES To determine the significance of Lipoprotein (a) (Lp(a)) as a risk factor for atherosclerotic lower limb peripheral vascular disease (PVD), and its relationship to other demographic and biochemical variables and disease pattern and severity. DESIGN Prospective case-control study. MATERIAL AND METHODS Demographic and biochemical risk factors, lipoprotein fractions and Lp(a) were measured in 200 patients with PVD and 200 age- and sex-matched control subjects. Lp(a) levels were correlated with traditional risk factors and clinical and vascular laboratory disease parameters. RESULTS Patients with PVD have a higher incidence of smoking, hypertension, and diabetes mellitus; and had significantly higher levels of serum cholesterol, triglycerides, LDL, VLDL, apolipoprotein B, fasting glucose, fibrinogen, plasminogen, haematocrit, white cell and platelet counts; but lower levels of HDL and apolipoprotein A1. Fasting Lp (a) concentration is an independent risk factor for PVD and is significantly higher in the patients (median = 26.1 mg/dl [4.8-195], mean = 36.5 +/- 32.6 mg/dl) than in controls (median = 18.2 mg/dl [5.4-216], mean = 27.2 +/- 28.1 mg/dl; p < 0.0001). In patients with PVD, Lp(a) correlated positively with plasma LDL, cholesterol, fibrinogen, renal disease, and apolipoprotein B. Fasting levels of > 24 mg/dl incurred a two-fold increase in risk of PVD. Patients with a higher Lp(a) have a significantly higher incidence of resting pain and ulcerations, and regression analysis confirmed smoking and Lp(a) level to be associated with the SVS category of disease severity. CONCLUSIONS Lipoprotein (a) is a significant independent risk factor for PVD. Lp(a) levels correlated with LDL, cholesterol, fibrinogen, apolipoprotein B and disease severity. An elevated Lp(a) level may be associated with more severe forms of PVD.

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.

Scientific paperPyloroplasty versus no drainage in gastric replacement of the esophagus

In a prospective randomized study of pyloroplasty versus no drainage, 200 patients (100 in each group) in whom the whole stomach was used for reconstruction following resection for esophageal carcinoma were studied. Only patients who underwent the Lewis-Tanner operation and who had a normal pylorus were included. There was no morbidity from the pyloroplasty procedure. Thirteen patients without drainage developed symptoms of gastric outlet obstruction, requiring prolonged post-operative parenteral nutrition, and reoperation was required in one patient. Four patients developed pulmonary complications associated with gastric distension, which resulted in fatal aspiration in two patients. Five patients had symptoms of outlet obstruction with eating at the time of their death. Mean and standard deviation of daily gastric aspirate was 161 +/- 88 mL in the pyloroplasty group and 233 +/- 142 mL for the control group (p = 0.23). Gastric emptying test showed mean T1/2 +/- standard deviation of 6.6 +/- 7.5 minutes in the pyloroplasty group and 24.3 +/- 31.5 minutes in the control group (p less than 0.001). More patients in the pyloroplasty group were able to tolerate a solid diet and at normal or increased amounts than were patients in the control group in the early postoperative weeks (p less than 0.01). In addition, control patients were found to have increased symptoms with meals, which were more frequent and of greater severity than symptoms in patients in the pyloroplasty group, even at 6 months after surgery (p less than 0.01). Therefore, we recommend a pyloroplasty for patients in whom the whole stomach is used for reconstruction after esophagectomy.

Endovascular stenting of superficial femoral artery stenosis and occlusions: results and risk factor analysis.

PURPOSE To determine the early and midterm results of femoro-popliteal angioplasty with adjunctive stenting and to identify factors affecting early and continuing success. METHODS Sixty-nine consecutive balloon angioplasty procedures on the superficial femoral artery (SFA) were performed in 60 limbs and 55 patients in the operating theater. Fifty-two percent of lesions were occlusions, and 87% involved the distal half or the whole segment of the SFA. Immediate endovascular stenting was used in all procedures, involving the placement of 105 stents, with a mean stented length of 13.8 cm. Twenty-nine procedures (43%) were performed for critical ischemia. Three-monthly duplex ultrasound was used for follow up assessment, with stenosis of > 50% defined as the endpoint for failure. The patient demographic and biochemical data, and procedural details were correlated with success criteria according to Society of Vascular Surgery standards. RESULTS Initial technical success by intent to treat was 92%, with four procedure-related complications and no deaths. Initial success by anatomic, hemodynamic and clinical criteria were 98.3, 96.7 and 93.3% respectively (92.2, 90.6 and 87.5% by intent to treat). Cumulative primary patency at 6, 12, and 24 months was 73.1, 62.6 and 53.8%, and secondary patency 84.9, 72.1 and 72.1% correspondingly. Significant factors relating to inferior patency were occlusions, stented segment length > 10 cm, procedure in claudicants, and the use of the Memotherm stent. CONCLUSIONS Angioplasty and stenting of the superficial femoral artery has acceptable primary and secondary patency rates even in the presence of long stenosis and occlusions. A duplex surveillance program is recommended for early detection and timely treatment of restenosis.

Femoral pseudoaneurysms in drug addicts.

Abstract. Femoral pseudoaneurysm is a serious complication in drug addicts who habitually inject via the groin. A total of 33 drug addicts presenting with 34 infected femoral pseudoaneurysms were treated in the Department of Surgery, the University of Hong Kong, Queen Mary Hospital from July 1993 to June 1996. There were 27 men and 6 women, with ages ranging from 23 to 76 years (mean 39.6 years). Positive intraoperative tissue cultures were seen in 29 (85%), with 17 being pure growth of methicillin-sensitiveStaphylococcus aureus (MSSA). Twenty-four pseudoaneurysms involved the femoral bifurcation and were treated by triple ligation of the common femoral, superficial femoral, and profunda femoris arteries. Seven other limbs underwent ligation of the common femoral artery alone, and three had superficial femoral artery ligation. Nineteen limbs had the external iliac artery ligated in addition to the femoral ligation for better proximal control. The mean postoperative ankle–brachial index (ABI) was 0.43 and 0.52 in those with triple ligation and those with single-vessel ligation, respectively. There was no hospital mortality, and all patients were discharged with a viable limb. The duration of follow-up ranged from 2 to 36 months (mean 15.5 months). Four patients were asymptomatic, but the rest suffered some degree of intermittent claudication. No delayed limb loss was identified. We conclude that systemic antibiotics active against MSSA are the antibiotics of choice in drug addicts with infected femoral pseudoaneurysms. Ligation and excision of the pseudoaneurysm without revascularization is safe, with acceptable morbidity and a low limb loss rate.

Optimal exposure of the proximal abdominal aorta: A critical appraisal of transabdominal medial visceral rotation

PURPOSE Adequate exposure of the upper abdominal aorta and its branches is a necessary prelude to safe and durable reconstruction of this aortic segment. Although a variety of approaches to this exposure have been described, few outcome data are available to assess the benefits and limitations of the different exposure options. In this series we report the results of the transabdominal medial visceral rotation (MVR) approach to exposure of the paramesenteric and pararenal aorta. METHODS One hundred eight operations were performed in 104 patients, representing 19.5% of all aortic reconstructions during a 5.5 year interval. Most patients had hypertension (n = 77, 71.3%) or a history of smoking (n = 83, 76.9%). Heart disease was present in one third of patients (n = 33) and a similar proportion had abnormal renal function (elevated creatinine level) before operation (n = 40, 37.0%). One third of patients (n = 34) had undergone previous aortic or aortic branch reconstruction. Eighty percent of procedures were elective (n = 87). Seventy-one patients (65.7%) required renal revascularization, usually for hypertension or elevated creatinine levels, whereas 37 patients (34.3%) underwent visceral reconstruction, most often for symptoms of chronic mesenteric ischemia. Only 22 patients required isolated infrarenal aortic repair. Most of the aortic lesions were aneurysmal (n = 42). Eighty percent of procedures (n = 88) required suprarenal or more proximal aortic clamping. The most frequently used reconstruction techniques were bypass (n = 39, 36.1%), endarterectomy (n = 18, 16.7%), or both (n = 23, 21.3%). RESULTS There were four intraoperative deaths (3.7%) and 15 postoperative deaths (13.9%). All intraoperative deaths and four postoperative deaths were related to hemorrhage and its complications. Visceral infarction was the most frequent cause of postoperative death. The intraoperative complications that were determined to be related to the medial visceral rotation approach included splenic injury (n = 23, 21.3%), one aortic injury, and one adrenal injury. The aortic injury was associated with substantial intraoperative bleeding and subsequent death. The postoperative complications resulting from MVR included pancreatitis (n = 5), which contributed to death in two patients, and possibly some of the cases of visceral infarction not associated with visceral reconstruction. The other common postoperative complications, cardiac (n = 25, 24.0%), pulmonary (n = 32, 30.8%), renal (n = 20, 19.2%), and infectious (n = 17, 16.3%), were attributed to the procedures performed. CONCLUSIONS Transabdominal MVR exposure of the upper abdominal aorta provides unrestricted access to the visceral branch-bearing segment of the aorta and places no limitations on the choice of arterial reconstruction technique. The associated morbidity and mortality rates are typical of patients undergoing these complex vascular repairs, but the frequency of splenic injury and postoperative pancreatitis is increased.

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.