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Biomedical subjects

S T Lai

Publications and source records attributed to S T Lai.

At least 55 records · Page 3Linked to original sources
PubMed1998

Absorbable PDS-II suture and nonabsorbable polypropylene suture in aortic anastomoses in growing piglets.

The long-term outcome of vascular anastomoses in children can be compromised by stenosis when the growth of the anastomosis does not match that of the vessels. This can be influenced by the suture material. We evaluated the suitability of the new generation of polydioxanone (PDS-II), an absorbable synthetic monofilament suture, in vascular surgery, in terms of permitting normal growth of aortic anastomoses. Ten piglets underwent primary end-to-end anastomosis of the thoracic aorta, five with PDS-II suture and five with conventional polypropylene (Prolene) suture. Six months after surgery, an aortogram was obtained for each animal. The piglets were then killed and the aortas were sent for pathologic examination. Complete absorption of suture material with slight dilatation of the anastomoses was found in all five pigs in the PDS-II suture group. We also found thrombus formation in one pig in this group. Mild stenosis of the anastomotic site was noted in all five pigs in the polypropylene suture group, but no intraluminal thrombus formation was seen. The degree of dilatation or stenosis within each group was not significantly different when intraluminal diameters were compared at three distinct sites in the reconstructed aorta (p > 0.05). The differences in vascular growth between the two groups were also not significant (p > 0.05). Histologic examination revealed less tissue reaction in the PDS-II suture group than in the polypropylene suture group. Thus, PDS-II seems to be a suitable suture material for anastomoses as far as vascular growth is concerned, but the possibility of aneurysm formation secondary to dilatation of the anastomotic site should be kept in mind.

Anastomosis, Surgical↗
PubMed1998

Computed tomography in the determination of surgical emergency for symptomatic abdominal aortic aneurysm.

BACKGROUND: What is the best surgical timing for symptomatic AAA? Surely, the answer depends on accurate and prompt diagnosis of 'rupture or not'. Abdominal CT is one of the reliable and familiar diagnostic tools. We will present our own CT classification method for symptomatic AAA which is used as the guideline for 'emergency or not'. METHODS: From January 1989 to January 1995, 52 patients with symptomatic AAA received diagnostic CT scan for quick disease differentiation and determination of surgical emergency. The findings were classified into four categories. Category I included 26 patients with intact aorta; Category II included four patients with contained retroperitoneal abdominal aortic leakage; Category III included 14 patients with contained massive retroperitoneal hematoma; and Category IV included eight patients with retroperitoneal or intraperitoneal active bleeding. RESULTS: Compared with the standard diagnosis of rupture via laparotomy, CT is an excellent tool, showing 88% sensitivity and 88% specificity. This is better than sonography, which has a high false-positive rate of 33% and low specificity of 62%. Hospital mortality was distinctive with 4.3% in Category I, none in Category II, 25% in Category III and 87.5% in Category IV. CONCLUSIONS: In our experience, CT scan is a better diagnostic tool than sonography for symptomatic AAA. Even the delay imposed by obtaining a preoperative CT scan in patients with possible ruptured aneurysm does not adversely affect the patient's outcome. The information obtained significantly aids not only preoperative but also intraoperative management.

Aged↗
PubMed1998

Endoscopic vein harvest for coronary artery bypass surgery.

BACKGROUND: Despite increased awareness of risk factors, wound complications continue to be a problem following coronary artery bypass graft (CABG) surgery. A minimally invasive alternative was therefore developed to reduce the risk of complications while providing the same benefits as the standard open vein harvest procedure. METHODS: Video-assisted endoscopic technique for vein harvest was introduced in our medical center in October 1996. The procedure was evaluated and compared with the standard open vein harvest procedure. With the endoscopic technique, small incisions were made, each about 2-3 cm at the selected access sites (groin and above and below the knee). An endopath subcutaneous dissector was subsequently inserted along the anterior surface of the saphenous vein with the assistance of an endoscope and video monitor. The venous side branches were detected and positioned using a vessel dissector. A ligaclip was applied and the branches were divided using endopath-scissors. In some cases, the venous branches were divided directly using the endopath-scissors. Therefore, the distal and proximal ends of the saphenous vein were isolated, ligated and divided. The harvested veins were used for CABG. Each patient was evaluated for length of surgery, hospital stay and morbidity. RESULTS: From October 1996 through May 1997, we performed 50 procedures using video-assisted endoscopic vein harvest. The results were compared with those from 106 patients who underwent standard open vein harvest during the same period. The rate of complications was 2% in the endoscopic group compared with 13.2% in the open group (p < 0.05). The average hospital stay was 7.2 days in the endoscopic group and 11.5 days in the open group (p < 0.05). Twelve weeks after the operation, all of the incisions healed with good cosmetic results in the endoscopic group. However, long visible scars were found in the patients in the open group. CONCLUSIONS: Endoscopic saphenous vein harvest provides a minimally invasive alternative to open vein harvest. It provides good cosmetic results without a hypertrophic scar and enables the patient to regain early ambulation.

Aged↗
PubMed1998

Minimally-invasive, direct coronary artery bypass grafting.

BACKGROUND: Minimally-invasive, direct vision coronary artery bypass grafting (MIDCAB) is a new surgical technique performed via limited thoracotomy in a beating heart without cardiopulmonary bypass. METHODS: From June 1996 to December 1996, MIDCAB was performed in 12 patients (all male, average age, 65.9 years). In 11 patients with left anterior descending coronary artery lesions, thoracotomy was performed via the left, fourth intercostal space and the pericardium was incised to identify the target site. About 8 cm of the left internal mammary artery was harvested. Bilateral anterolateral thoractomy was performed in one patient with left anterior descending and right coronary artery lesions. Anastomosis was performed under direct vision in the beating heart without cardiopulmonary bypass. RESULTS: MIDCAB was performed successfully without morbidity. The patients' average stay in the intensive care unit was 1.8 days. No patient had any early cardiac event requiring additional surgery or percutaneous transluminal coronary angioplasty. Postoperatively, all patients were asymptomatic and their recovery was uneventful. CONCLUSIONS: Our initial experience indicates that MIDCAB offers good results and is a treatment option for selected patients with left anterior descending and/or right coronary artery lesions.

Aged↗
PubMed1997

Haemolysis complicating acute viral hepatitis in patients with normal or deficient glucose-6-phosphate dehydrogenase activity.

Haemolytic anaemia as a complication of acute hepatitis has been reported in up to 23% of patients. However, the incidence may rise up to 70-87% in patients who have glucose-6-phosphate dehydrogenase (G6PD) deficiency. Massive intravascular haemolysis with renal failure, hepatic encephalopathy and even death have been reported. In our retrospective study of patients with acute viral hepatitis, the overall incidence of acute haemolysis was 4% (17/434). Only 53% (9/17) of them had G6PD deficiency. Patients with acute haemolysis had a significantly higher peak bilirubin level and required more prolonged hospitalization. Since hepatitis A virus vaccination, unlike hepatitis B virus vaccination, is not yet recommended for routine immunization, we suggest subjects who are G6PD-deficient should be vaccinated against hepatitis A. In endemic areas of hepatitis A virus infection, universal immunization remains the definitive answer.

Adolescent↗
PubMed1997

Acute viral hepatitis in Hong Kong: a study of recent incidences.

Acute hepatitis patients admitted to a referral centre from January 1995 through December 1995 were studied to determine the seroprevalence of the hepatitis viruses and related risk factors. Of the 434 patients with acute viral hepatitis, the episodes due to hepatitis A, B, C, D, and non-A, non-B, non-C, (non-ABC) were 214 (49.3%), 163 (37.6%), 7 (1.6%), 0 (0%), and 50 (11.5%), respectively. Acute hepatitis A and non-ABC hepatitis commonly occur in late spring and early summer and are probably related to the intake of shellfish and travel to endemic areas. Approximately 60% of cases of symptomatic hepatitis B infection were acute exacerbations of chronic infection. Sexual exposure was the single most important risk factor for acute hepatitis B infection. The rarity of acute hepatitis C and D might be related to the low rate of intravenous drug use in our locality. Hepatitis E virus probably contributed significantly to the cases of non-ABC hepatitis. Further studies are needed to establish the importance of various causative agents of acute hepatitis in Hong Kong.

Journal Article↗
PubMed1997

Management of the complications of chronic liver disease.

The complications of severe chronic liver disease result from hepatocellular failure, portal hypertension, or a combination of both. Acute variceal haemorrhage can be effectively managed by drugs, endoscopic techniques, balloon tamponade, and surgery. The advent of the transjugular intrahepatic portosystemic stent-shunt has offered a new therapeutic option. Prevention of re-bleeding also depends on endoscopic therapy or surgery. Beta-blockers have been shown to be useful, not only in preventing re-bleeding, but also in primary prophylaxis. Spontaneous bacterial peritonitis has proved to be preventable by antibiotic prophylaxis. Massive ascites can be satisfactorily treated by repeated large-volume paracentesis and albumin infusion. Hepatic encephalopathy responds to protein restriction and reduction of bowel ammonia production by classical and novel agents. Liver transplantation may be used for those with hepatorenal and hepatopulmonary syndromes and it is the ideal treatment of choice for all suitable patients with terminal chronic liver disease.

Journal Article↗
PubMed1997

Plasmodium infection unmasked by corticosteroid therapy.

In the past four years, we have encountered three patients in whom malaria parasites were found incidentally in their blood when they were receiving corticosteroid therapy. Although there is little direct evidence that corticosteroid therapy can activate human malaria, animal studies have successfully demonstrated the recrudescence effect of immunosuppression on malaria infection.

Journal Article↗
PubMed1997

Improved postoperative pain relief via preemptive analgesia in relation to heart rate variability for coronary artery bypass grafting: a preliminary report.

BACKGROUND: Sudden cardiac death remains to be the most devastating outcome for patients who undergo cardiac surgery. Surgical stress in combination with postoperative pain are key factors of such tragedy. Preemptive analgesia (PA) is supposed to provide optimal postoperative pain management, and epidural morphine infusion to provide effective pain relief and stress reduction after cardiac surgery. Heart rate (HR) variability seems to correlate to the survival of acute myocardial infarction (AMI) patients. This study was conducted to evaluate the benefits of PA for coronary artery bypass grafting (CABG) patients in the sense of improvement in postoperative respiratory and cardiovascular functions, and its correlation to HR and HR variability. METHODS: A total of 40 patients who underwent CABG from June 1995 to December 1995 were randomly selected and divided into two groups (Group A and Group B). Group A (n = 20) was treated with conventional postoperative analgesia of intravenous (i.v.) meperidine HCl (Demerol). Group B (n = 20) was treated with PA using epidural infusion of local anesthetics plus ketamine and morphine during surgery and then using intermittent epidural morphine infusion for postoperative pain control when necessary, and Demerol was given intravenously as in group A. Postoperative pain intensity was measured by a modified visual analogue pain scale from 0 to 10 (0 = no pain, 10 = severe pain). Perioperative HR and HR variability data based on 24-hour electrocardiograph (ECG) Holter monitoring along with data on respiratory and cardiovascular functions were gathered, analyzed, and compared between Group A and Group B. RESULTS: Effective analgesia (mean pain score of 0-2) was achieved in 50% of Group A patients and 75% of Group B patients. Group B with the reduced dosage of demerol also had the benefits of smaller degree of respiratory insufficiency, earlier extubation, and less incidence of re-intubation as compared with Group A. For HR comparison between Group A and Group B, statistically significant differences (p < 0.05) were observed in 3 out of the 16 postoperative time segments. For HR variability comparison between Group A and Group B, statistically significant difference (p < 0.05) was observed in one of the time segments while another segment showed marginal significance (p = 0.061). Group B patients also maintained better overall respiratory and cardiovascular functions. CONCLUSIONS: PA method through the use of epidural anesthesia along with morphine infusion provided better postoperative pain relief and more stable respiratory and cardiovascular functions in our patients with cardiac surgery. Although the differences in HR and HR variability between the control and the PA groups were not statistically significant throughout the period studied, the potential benefits of better understanding the relationship between postoperative pain control and HR variability justify further studies to be conducted.

Aged↗
PubMed1997

Surgical repair of Ebstein's anomaly.

BACKGROUND: Ebstein's anomaly represents a congenital structural deformity of the tricuspid valve associated with a wide spectrum of morphologic and physiologic abnormalities. Valvuloplasty and tricuspid valve replacement are the main surgical treatments. Plication of the atrialized right ventricle and valvuloplasty of the tricuspid valve can achieve satisfactory clinical results. Two surgical techniques, known as Danielson's and Quaegebeur's methods, are often used clinically. This study was conducted to compare the postoperative results between both methods in treatment of Ebstein's anomaly. METHODS: Valvuloplasty of tricuspid valve and the plication of atrialized right ventricle were performed in 8 out of 17 patients with Ebstein's anomaly in our hospital from January 1986 to August 1996. Danielson's method was used in six of eight patients, and Quaegebeur's method was used in the remaining two patients. There were three males and five females, aged from 8 months to 61 years (mean: 14.1 years). RESULTS: All patients achieved clinical improvement in cardiothoracic ratio and heart functional class. Cardiac arrhythmia was the likely cause of death in two patients treated by Danielson's method, and one patient developed complete atrioventricular (A-V) block postoperatively. By Quaegebeur's method, all patients survived, but a permanent pacemaker was implanted for both patients due to their preoperative complete A-V block. CONCLUSIONS: Both methods achieved satisfactory postoperative results. However, Quaegebeur's method seems to be more effective because it provided a simultaneous reconstruction of both tricuspid valve and right ventricle without the need for additional excision of the right atrium.

Adolescent↗
PubMed1996

Resurgence of cholera in Hong Kong.

Cholera is one of the three diseases subject to the International Health Regulations. After a period of over 30 years, the seventh pandemic of cholera, which started in South East Asia in 1961, still shows no sign of a decline. On the contrary, it has increased its severity and invaded many other countries in Africa and Latin America. In the last two years, there has been a recrudescence of the disease in South East Asia and Western Pacific Regions. The discovery of a new strain of Vibrio cholerae 0139 in these regions is causing concern in view of its potential to cause major epidemics and higher mortality. Hong Kong had two intensive outbreaks of cholera in the last two years. The cause of these outbreaks was not clear, but adverse environmental conditions and increasing pollution of coastal waters have been implicated. The spread of cholera knows no geographical boundaries. There is a need for intensified efforts among health authorities in the affected areas to prevent the international spread of the disease.

Adult↗
PubMed1996

A quantitative analysis of symptoms of non-ulcer dyspepsia as related to age, pathology, and Helicobacter infection.

BACKGROUND: Non-ulcer dyspepsia (NUD) has been attributed to gastritis and Helicobacter infection. The Sydney classification enables dyspepsia symptoms to be assessed quantitatively in relation to Helicobacter infection and topographic pathology in different gastric compartments. METHODS: In this study of 348 patients with NUD we studied the unconfounded effects of age, pathology, and Helicobacter. Endoscopic findings, dyspeptic symptoms, and age were recorded prospectively. Multiple logistic regression was used to evaluate the independent effects of age, pathology, and Helicobacter. RESULTS: Ulcer-like pain was negatively related to age (odds ratio = 0.75/10 years; P < 0.001). A high density of Helicobacter at the antrum but not elsewhere in the stomach was positively related to ulcer-like pain (odds ratio = 3.38; P < 0.002). Adjusted for age, none of the endoscopic (P > 0.19) and histopathology findings (P > 0.09) played an important role in NUD. CONCLUSION: Age was the most important determinant of dyspeptic symptoms, but not pathology or Helicobacter.

Abdominal Pain↗
PubMed1996

Association of self-limited cytomegalovirus colitis and shigellosis in an immunocompetent patient.

Cytomegalovirus (CMV) infection of the colon has been rarely reported in immunocompetent patients. Patients with severe acute illness or disseminated CMV infection have high mortality. In contrast, the patients with local injury of the colon due either to other gastrointestinal infections or to anal intercourse, who are otherwise healthy, usually have self-limited disease. The CMV infection is believed to be the bystander and may be treated conservatively. Concomitant CMV colitis and other gastrointestinal infections occur exclusively in immunosuppressed patients. We report, to our knowledge, the first case of co-infection of the colon with CMV and Shigella in an immunocompetent patient. The hypothesis is that the mucosal damage caused by Shigella infection may predispose the colon to secondary CMV invasion.

Colitis↗
PubMed1994

Incidence of post-transfusion hepatitis before and after screening for hepatitis C virus antibody.

To evaluate the effectiveness of screening test for antibody to hepatitis C virus (anti-HCV), the incidence of acute post-transfusion HCV infection in patients who underwent cardiovascular surgery and received blood transfusion was studied. All patients were followed prospectively with serum biochemistry tests and viral hepatitis markers before and periodically for at least 6 months after cardiovascular surgery. None of them had history of liver disease and none tested positive for anti-HCV prior to blood transfusion. Before blood donors were screened for anti-HCV with a second-generation HCV diagnostic kit, 28 (12.4%) of 226 patients or 0.49% of 5,690 unit transfusion had seroconverted to anti-HCV during a 6-month follow-up. The incidence of post-transfusion hepatitis (PTH) C in 91 patients who had received 1-12 units transfusion was significantly lower than in 135 patients who had received more than 12 units transfusion (6.6 vs. 16.3%, p < 0.05). However, none of the 87 transfused patients, since anti-HCV screening in July 1992, developed PTH C (p < 0.05). The result demonstrates that screening for anti-HCV by a more sensitive second-generation HCV diagnostic assay may protect the patients studied from PTH C. It further provides a firm argument for the necessity of a nation-wide blood donor screening.

Adolescent↗
PubMed1994

Early results of the advanced coronary endarterectomy combined with CABG in the treatment of coronary artery occlusive disease.

BACKGROUND: Coronary Endarterectomy is a controversial but effective procedure for diffuse coronary artherosclerosis. Between April 1991 and January 1993, 57 patients in VGH-Taipei who had their diffuse coronary artery disease treated with combined endarterectomy and coronary artery bypass grafting (CABG). METHODS: One hundred and thirty-eight endarterectomies were performed, including 6 on the left main coronary artery system, 77 on the left anterior descending coronary artery system, 15 on left circumflex coronary artery system and 40 on the right coronary artery system (an average of 2.42 endarterectomies/patient). For graft conduit, great saphenous vein was used in 149 anastomoses, left internal mammary artery in 21, right internal mammary artery in 6 and right gastroepiploic artery in 4. The mean number of distal graft anastomoses was 3.15 per patient. Additional procedures were performed in 8 patients (14%): two patients required aortic valve replacement, one patient had mitral valve replacement, one had mitral annuloplasty, one had VSD repair and three had left ventricle aneurysm plications. The mean aortic clamp time was 108.8 +/- 30.5 minutes. RESULTS: The early mortality rate was 5.3%. The late mortality rate was 3.5%. During follow-up of mean 17.5 months, 98% of survivors were asymptomatic or in improved condition. CONCLUSIONS: Although endarterectomy is still a debatable procedure, it is valuable especially for the diffusely diseased arteries.

Aged↗