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Biomedical subjects

M B Izzat

Publications and source records attributed to M B Izzat.

At least 19 recordsLinked to original sources
PubMed1999

A survey on partial left ventriculectomy in the Asia-Pacific region.

BACKGROUND: There has been increasing interest in partial left ventriculectomy as a new therapy for end-stage heart failure. Because the most significant impact of this development is likely to be in regions where heart transplantation is largely unavailable, we conducted a survey among a group of cardiac surgeons based in the Asia-Pacific region to evaluate their overall views on partial left ventriculectomy procedures. METHODS: A questionnaire was sent to surgeons from 65 major institutions in 17 countries and regions in the Asia-Pacific. Questions examined current demographics and opinions regarding potential application and future prospects of this operation. RESULTS: Surveyed surgeons were based in equal proportions in academic, government, and private practice institutions. One third of respondents have already performed partial left ventriculectomy operations, largely in small numbers. In total, 86 procedures were performed with 75% hospital survival rate. Failures were thought to be caused by limited knowledge about patient selection criteria and lack of experience with operative technique and perioperative care. The majority of respondents believe that partial left ventriculectomy is potentially a valuable intervention and intend to perform more cases. Nevertheless, most surgeons identified the need to have larger clinical experience, to perform randomized trials against other therapeutic modalities, and to improve perioperative care. CONCLUSIONS: Although all surgeons recognize that more knowledge is needed before partial left ventriculectomy becomes a standard procedure, it is clear from this survey that the procedure has rapidly gained interest, with more surgeons seeking to learn it.

Cardiac Volume↗
PubMed1999

Favorable scanning electron microscopic findings of stapled saphenous vein-carotid artery anastomoses.

BACKGROUND: In the progress toward "off-pump" endoscopic coronary artery surgical procedures, new techniques for coronary artery anastomoses are being developed. One such approach is the use of nonpenetrating titanium clips. We evaluated the quality of anastomoses achieved using this technique in a porcine model of saphenous vein-carotid artery grafting using scanning electron microscopy. METHODS: Bilateral saphenous vein-carotid artery interposition grafts were implanted in 10 "white race" pigs, using the nonpenetrating clips in one side of the neck and conventional hand suturing on the opposite side. One week after operation, the grafts were harvested. RESULTS: All grafts were patent 7 days after operation, and 40 anastomoses underwent scanning electron microscopic study. In all samples, the luminal surfaces of both the carotid artery and vein graft were covered by a continuous layer of endothelial cells up to the anastomosis. Anastomotic sites in all clipped samples and most of the sutured anastomoses were completely endothelialized, and anastomotic clefts were indistinguishable. However, in 25% of sutured specimens, the suture material remained clearly visible inside the lumen of the vessel, and the subendothelial matrix remained exposed, with extensive fibrin, red blood cells, and platelet deposition on its surface. CONCLUSIONS: Because the endothelial coverage consistently appeared to be complete and the subendothelial matrix was not exposed, it is likely that the risk of early anastomotic thrombosis is reduced by using the nonpenetrating titanium clips.

Anastomosis, Surgical↗
PubMed1999

Avoiding cardiopulmonary bypass in multivessel CABG reduces cytokine response and myocardial injury.

BACKGROUND: Proinflammatory cytokines play a key role in the inflammatory cascade after cardiopulmonary bypass and may induce cardiac dysfunction. We compared the production of cytokines and the degree of postoperative myocardial injury in patients with multivessel coronary artery disease undergoing coronary artery bypass grafting through median sternotomy with or without cardiopulmonary bypass. METHODS: Forty-four consecutive patients were studied. Patients were selected for off-pump coronary artery bypass grafting whenever complete revascularization was technically feasible. There were no differences between the two groups with respect to age, sex, symptoms, or functional class. Plasma levels of tumor necrosis factor-alpha, interleukin (IL)-6, IL-8, and IL-10 were measured before the operation, at the end of the procedure, and 2, 4, 8, 24, and 48 hours thereafter. Levels of the MB isoenzyme of creatine kinase and cardiac troponin-I were also measured after the operation. RESULTS: The number of grafts was 2+/-0.7 in the off-pump group (n = 18) and 3+/-0.8 in the cardiopulmonary bypass group (n = 26). There were no deaths or major complications in either group. Levels of tumor necrosis factor-alpha were low in both groups. No significant intergroup differences were noted regarding serial IL-6 measurements. However, IL-8 and IL-10 levels after the operation were lower in the off-pump group (IL-8, 4+/-1 versus 38+/-12 pg/mL, p < 0.01; IL-10, 5+/-2 versus 191+/-33 pg/mL, p < 0.001). Whereas postoperative creatine kinase-MB values were similar in the two groups, cardiac troponin-I levels were significantly lower in the off-pump group (8 hours, p < 0.005; 24 hours, p < 0.02, respectively). Moreover, cardiac troponin-I values 24 hours after operation correlated strongly with IL-8 levels (r = 0.61, p < 0.005), indicating that the degree of myocardial injury may be related to IL-8 production. CONCLUSIONS: Compared with conventional coronary artery bypass grafting, coronary revascularization without cardiopulmonary bypass is associated with reduced cytokine responses and less myocardial injury.

Cardiopulmonary Bypass↗
PubMed1999

Early experience with partial left ventriculectomy in the Asia-Pacific region.

BACKGROUND: We report our early experience with partial left ventriculectomy done by a group of cardiac surgeons in the Asia-Pacific region. METHODS: Partial left ventriculectomy was done in 48 patients (mean age, 43 years) with advanced symptomatic cardiomyopathy. The origin of cardiomyopathy was idiopathic in 30 patients, valvular in 10, ischemic in 3, peripartum in 3, sarcoidosis in 1, and viral myocarditis in 1. Procedures performed on the mitral valve were repair with Alfieri method in 8 patients, ring annuloplasty in 2, and replacement in 25. RESULTS: Seventy-seven percent of patients required myocardial support for weaning from cardiopulmonary bypass, and the overall in-hospital mortality rate was 27%. Mean follow up was 6.5 months (range, 1 to 18 months), and patient survival at 1, 3, and 6 months after discharge was 91%, 88%, and 84%, respectively. Sixty-five percent of survivors with idiopathic and valvular disease achieved significant and sustained improvement in ventricular contractility and symptoms, but there were no clear symptomatic benefits from partial left ventriculectomy in patients with cardiomyopathy from other causes. Most cases of late recurrence of heart failure symptoms (90%) appeared to be related to the development of progressive mitral incompetence. CONCLUSIONS: After partial left ventriculectomy left ventricular function improved in patients with idiopathic and valve related cardiomyopathies. Late deterioration was related to the development of significant mitral valve incompetence postoperatively, hence definitive mitral valve repair or replacement at the time of the partial left ventriculectomy procedure is advised.

Adolescent↗
PubMed1999

Video-assisted thoracoscopic thymectomy for myasthenia gravis.

Thymectomy is an established therapy in the management of generalized myasthenia gravis, in addition to medical treatment. However, the optimal surgical approach to thymectomy has remained controversial. There are advocates for transternal, transcervical approaches or "maximal" thymectomy. Video-assisted thoracic surgery (VATS) presents a new approach to thymectomy and forms the basis of this article, in which we discuss patient selection, technique, and results. We believe complete thymectomy, comparable with the transternal approach, could be achieved by VATS. Our intermediate-term results compare well with other surgical techniques. By minimizing chest wall trauma, VATS not only causes less postoperative pain, shortens hospital stay, gives better cosmetic results but also leads to wider acceptance by patients (and their neurologists) for earlier surgery. However, the true role of this approach in thoracic surgery awaits long-term results.

Anesthesia, General↗
PubMed1999

Video-assisted thoracic surgery: a renaissance in surgical therapy.

Within a few years, video-assisted thoracic surgery (VATS) has become the accepted or preferred approach over a wide range of thoracic procedures. The authors review the development of this technique, the basic operative strategies and the current surgical indications. Technical pitfalls and future developments are also discussed.

Humans↗
PubMed1999

Increased secretion of basement membrane-degrading metalloproteinases in pig saphenous vein into carotid artery interposition grafts.

Late saphenous vein bypass graft failure in humans involves medial and neointimal thickening as the result of migration and proliferation of vascular smooth muscle cells (SMCs). Recent work on angioplasty indicates that basement membrane-degrading metalloproteinases (MMPs) cooperate with growth factors to mediate SMC migration and proliferation. We sought evidence here for a similar role in experimental vein grafts in pigs. Tissue levels and secretion of MMP-2 and MMP-9 were compared by quantitative zymography in veins and grafts removed 2 to 168 days after implantation. Pro and active forms of MMP-2 were present in veins, but levels were increased in vein grafts after 7 days (4- and 6-fold, respectively) and 28 days (3-fold for both), returning to values in veins after 168 days. MMP-9 was not detected in veins, was increased in grafts after 2 days, further increased after 7 days (6-fold) and 28 days (15-fold), and declined to undetectable levels by 168 days. Immunocytochemistry detected increased expression of MMP-2 and MMP-9 with the same time course. MMP-2 was widely distributed, whereas MMP-9 was concentrated in highly proliferative SMCs at the superficial layers of the thickened neointima. We conclude that increased production of the basement membrane-degrading MMP-2 and MMP-9 spanned the period of neointima formation and SMC proliferation in experimental vein grafts. MMPs therefore constitute new therapeutic targets for reducing late vein graft failure.

Animals↗
PubMed1999

Routine intraoperative angiography improves the early patency of coronary grafts performed on the beating heart.

OBJECTIVES: The techniques of performing coronary revascularization without cardiopulmonary bypass are rapidly evolving. However, concern remains regarding the accuracy of coronary artery anastomoses performed on the beating heart. This report reviews the use of intraoperative angiography in the critical appraisal of "off-pump" coronary artery bypass graft (CABG) surgery. PATIENTS: Intraoperative angiography was performed in 24 consecutive patients undergoing CABG surgery without cardiopulmonary bypass. In all, 24 left internal mammary artery (LIMA) grafts and 18 saphenous vein bypass grafts were assessed for patency, anastomosis quality, distal and proximal runoff, and correct placement. RESULTS: All of the saphenous vein-to-coronary artery anastomoses were widely patent, although two patients (8%) required revision of their LIMA grafts on the basis of angiographic findings. CONCLUSION: Intraoperative angiography permits the surgeon to immediately appraise the CABG and to revise, if necessary, any graft abnormality, thus potentially eliminating the need for early repeated surgery. The practice of routine intraoperative angiography is likely to improve the outcome of CABG surgery on the beating heart.

Coronary Angiography↗
PubMed1999

Video-assisted thoracoscopic thymectomy.

Video-assisted thoracoscopic surgery (VATS) provides a new, alternative approach to thymectomy and has several advantages over the other established techniques. However, even among surgeons using this approach, there are differences in the actual technique. We prefer the right approach using conventional instruments. The rationale behind our technique is discussed.

Humans↗
PubMed1998

Hemodynamic performance of the 21-mm St. Jude BioImplant prosthesis using dobutamine Doppler echocardiography.

This study examines the hemodynamic performance of small size St. Jude BioImplant aortic prostheses using dobutamine echocardiography. Eleven patients (3 women, mean age 75 years) who had undergone aortic valve replacement with a size 21-mm St. Jude BioImplant aortic prostheses at 10.8 +/- 5.1 months (SD) previously were studied. Dobutamine infusion was started at a rate of 5 microg/kg/min and increased to 10 microg/kg/min, and subsequently to 20 microg/kg/min at 15-minute intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, mean gradient, and the performance index across each prosthesis were calculated and cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract. Stress dobutamine increased heart rate and cardiac output by 51% and 56%, respectively (both p <0.0001), and the mean transvalvular gradient increased from 30.1 +/- 7.5 mm Hg at rest to 49.3 +/- 11.5 mm Hg at maximum stress (p <0.0005). The performance index increased progressively from 0.29 +/- 0.05 at rest to 0.40 +/- 0.10 at maximum stress (p <0.0005). Regression modeling analyses demonstrated that the maximum stress gradient was independent of all variables except the resting gradient (p = 0.03). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress. Thus, these data demonstrate that the size 21-mm St. Jude BioImplant prosthesis exhibits suboptimal hemodynamic performance with transvalvular gradients consistent with mild to moderate aortic stenosis, both at rest and under stress conditions.

Adrenergic beta-Agonists↗
PubMed1998

Video-assisted interventional bronchoscopy. The Hong Kong experience.

BACKGROUND: Major airway obstruction due to benign or malignant etiology is not uncommon and is always distressing. Intraluminal stenting has been shown to be a safe and effective approach for symptomatic relief in selected patients based on the European and North American experience. METHODS: We reviewed our experience in Hong Kong on airway stenting over a 19-month period. RESULTS: From February 1994 to August 1995, 33 silicone stents (Dumon stent, Cometh, Marseille, France) were placed in 23 patients (20 males, three females with mean age 61.4 years, range from 26 to 81). Eighteen stents were placed in the trachea, nine in the left main stem, five in the right main stem, and one Y-stent over the carina. Twelve patients had esophageal carcinoma involving the airway, seven had bronchial carcinoma, one had metastatic carcinoma, and three had benign strictures (of which two were due to tuberculosis). There was no procedural related mortality. Stent migration occurred in four patients (17%) and required stent change. Symptoms were improved in all patients as documented by the visual analogue scale. CONCLUSION: Our experience represents the "stentable" diseases seen in Hong Kong, where carcinoma of the esophagus (and tuberculosis) remains prevalent. We conclude that intraluminal stenting remains a safe and effective approach in selected patients with critical airway stenosis. Complications, however, do exist and should be realized by the operator, the patients, and their families.

Adult↗
PubMed1998

Thoracoscopic operations on reoperated chests.

BACKGROUND: A previous operation is generally considered to be a relative contraindication to the minimal access approach. We reviewed our combined experience from three centers with video-assisted thoracic surgery on reoperated chests. METHODS: From September 1992 to December 1996, 2,477 patients underwent video-assisted thoracic surgery of whom 40 patients (33 men; age range, 9 to 78 years) had prior operations on the ipsilateral side of the chest: 23 after prior open procedures (22 thoracotomies, 1 median sternotomy) and 17 after video-assisted thoracic surgery. The second procedures consisted of bullectomy or bulla ligation (8), mediastinal and hilar mass biopsy (8), wedge lung resection (6), pericardial window (5), lung volume reduction (4), redo thoracodorsal sympathectomy (3), talc insufflation alone (3), decortication (2), and suturing of a pleural rent (1). RESULTS: Adhesions were noted in all patients ranging from minimal to strong fibrous adhesions. However, in only 2 patients (5%) were the procedures abandoned because of adhesions. Video-assisted thoracic surgery was safely completed in all other patients. There was no mortality or intraoperative complications and mean hospital stay was 5.1 +/- 3.2 days (range, 0 to 17 days). CONCLUSIONS: Video-assisted thoracic surgery on reoperated chests is feasible and does not carry a higher morbidity or mortality compared with first-time operations, even though it may be technically more difficult. Experience and clinical judgment, however, are required to select these patients for reoperation with video-assisted thoracic surgery.

Adolescent↗
PubMed1998

Training model for "beating-heart" coronary artery anastomoses.

The principal technical challenge in "off-pump" coronary surgery is to perform an accurate coronary anastomosis on a beating heart. For the purpose of training our residents in performing off-pump coronary artery anastomoses, we have developed a mechanical heart simulator in which trainees can practice performing these anastomoses repeatedly until a satisfactory level of skill and confidence is attained.

Anastomosis, Surgical↗