Mohammad Bashar Izzat

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

BACKGROUNDnProinflammatory 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.nnnMETHODSnForty-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.nnnRESULTSnThe 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.nnnCONCLUSIONSnCompared with conventional coronary artery bypass grafting, coronary revascularization without cardiopulmonary bypass is associated with reduced cytokine responses and less myocardial injury.

The effects of cardiopulmonary bypass temperature on neuropsychologic outcome after coronary artery operations: A prospective randomized trial☆☆☆★★★♢

UNLABELLEDnThe effect of systemic perfusion temperature on postoperative cognitive function was investigated in 96 adult patients undergoing elective coronary revascularization with cardiopulmonary bypass at 28 degrees C, 32 degrees C, or 37 degrees C. Neuropsychologic performance was assessed 1 day before the operation and 6 weeks after the operation. Five tests were adapted from the Wechsler Adult Intelligence Scale and two from the Wechsler Memory Scale.nnnRESULTSnNo patients had major neurologic complications. Ninety-three patients completed the five Wechsler Adult Intelligence Scale tests, but only 70 went on to complete the Wechsler Memory Scale tests as well. In these, there was an effect of cardiopulmonary bypass temperature on the number of neuropsychologic tests in which there was a preoperative to postoperative deterioration (p = 0.021), the number with bypass at 37 degrees C being significantly greater than the number with bypass at 32 degrees C (p = 0.015). Subsidiary analyses using a multivariate linear model examined the effect of cardiopulmonary bypass temperature on the magnitude of change, with or without allowing for other possible confounding influences. There was an adverse effect of normothermic (37 degrees C) versus moderately hypothermic (32 degrees C) perfusion---more convincingly displayed in the analyses of all seven scores rather than just the Wechsler Adult Intelligence Scale scores. Further cooling to 28 degrees C conferred no additional benefit in terms of cognitive function. The importance of the deterioration is open to question.

A taste of Chinese medicine

We report a case of profound anticoagulation caused by interaction between warfarin and danshen, a widely used Chinese herbal medicine, in a patient who had undergone mitral valve replacement. Patients taking warfarin should be warned not to take this herb. In addition, physicians should be alert to the possibility of an interaction with herbal medicine when anticoagulation control becomes difficult and no other causes are apparent.

External stenting reduces early medial and neointimal thickening in a pig model of arteriovenous bypass grafting

The long-term clinical success of coronary artery bypass grafting with autologous saphenous vein is limited by progressive medial and neointimal thickening in the graft and superimposed atherosclerosis. We sought to reduce wall thickening by applying an external stent to experimental grafts in pigs. The diameter of the stent was designed to allow unrestricted initial expansion of the vein in response to arterial pressure and the stent material was highly porous so as to minimize adventitial [correction of advential] disruption. Four weeks after graft implantation, stented grafts had a larger lumen (11.2 +/- 6.2 [standard deviation] mm2 versus 7.6 +/- 3.4 mm2, p < 0.05, n = 9) and an almost fourfold thinner media (0.14 +/- 0.08 versus 0.49 +/- 0.22, p < 0.001) and neointima (0.10 +/- 0.07 versus 0.35 +/- 0.24, p < 0.001) than paired unstented grafts in the same animals. Cell proliferation was also greatly reduced by stenting in the neointimal and medial layers. The stenting procedure devised here is readily applicable to clinical coronary bypass grafts.

Is video-assisted thoracoscopic lobectomy a unified approach?

BACKGROUNDnFew surgeons worldwide currently perform video-assisted thoracoscopic (VAT) lobectomy. We conducted a questionnaire survey of this selected group of surgeons to gain insight into their current practice.nnnMETHODSnA survey with 25 questions on VAT lobectomy including operative approaches, techniques, its role in their practice, and limitations were mailed to 45 thoracic surgeons worldwide who are believed to perform this operation.nnnRESULTSnThirty-three completed questionnaires were analyzed. Among those surgeons practicing VAT lobectomy, the vast majority work in an academic or government institution and have at least 5 years of practice experience. Two thirds reported that at least 40% of all their thoracic procedures are currently performed using VAT techniques. However, considerable variations exist regarding preference for VAT lobectomy (one third uses VAT techniques in less than 10% of all lobectomies performed, whereas another third uses it in more than 40% of lobectomies), their approaches to mediastinal and hilar lymph nodes, and their operative techniques. The latter range from a purely endoscopic technique to one that is more appropriately termed minithoracotomy with video-assistance when the surgeons operate primarily by looking through the utility thoracotomy. There were no significant differences in the practices of surgeons working in different continents, except that Asian surgeons were more likely to use suture ligation as opposed to a staple-cutter on pulmonary vessels.nnnCONCLUSIONSnVideo-assisted thoracoscopic lobectomy is not a unified approach. Considerable variations exist among the small group of surgeons performing this procedure, in their approach to surgical oncology as well as the operative technique. Distinctions in these different operative approaches must be made before one can make a meaningful comparison of results. Different terms should probably be introduced to further clarify the exact techniques used.

Macro-porosity is necessary for the reduction of neointimal and medial thickening by external stenting of porcine saphenous vein bypass grafts.

BACKGROUNDnplacing external non-restrictive macro-porous stents around porcine vein grafts prevents neointima formation and medial thickening in both the short and long term. Whether the porosity of the stent material influences this effect, however, has not been determined. Therefore, the effect on neointimal and medial thickening of external macro-porous (polyester) and micro-porous (polytetrafluorethylene) stents of equal diameter were compared. The effect on expression of platelet-derived growth factor (PDGF), a potent mediator of vascular smooth muscle cell migration and proliferation and its receptors was also investigated.nnnMETHODS AND RESULTSnsaphenous vein-carotid artery interposition grafting was performed in Landrace pigs with external placement of 8 mm diameter macro- and micro-porous stents contralaterally. One month after surgery, graft wall dimensions, PDGF and PDGF receptor expression and cell proliferation using proliferating cell nuclear antigen (PCNA) were measured on histological sections. Macro-porous stents significantly reduced neointimal and medial thickening compared with micro-porous stents (0.1+/-0.02 vs. 0.25+/-0.03 mm, P<0.002, and 0.10+/-0.02 vs. 0.17+/-0.02 mm, P<0.014, respectively). Macro-porous stents significantly reduced the percentage of cells expressing PDGF and PCNA, compared with micro-porous stents (36+/-9 vs. 80+/-7, P < 0.002, and 11+/-3 vs. 21+/-2, P < 0.02, respectively). The percentage of cells expressing PDGF receptors was similar with both the stent types. Adventitial microvessel formation occurred across macro-porous stents but was markedly suppressed by micro-porous stents.nnnCONCLUSIONSnporosity is crucial to the efficacy of external stents in reducing neointima formation in porcine vein grafts. Decreases in PDGF expression and cell proliferation accompany the reduction in neointima formation. In addition, macro-porous stents allow adventitial microvessels to connect with the vasculature outside the stent, thereby potentially improving oxygenation. Although external stenting is highly effective in reducing neointima formation after vein grafting, the properties of the stent material necessary for this effect have not been defined. This study establishes that macro-porosity is one essential feature required to reduce PDGF expression cell proliferation and neointima formation.

Comparison of hemodynamic performances of St. Jude Medical and Carbomedics 21 mm aortic prostheses by means of dobutamine stress echocardiography

Dobutamine stress Doppler echocardiography was used to compare the hemodynamic performance of two small aortic bileaflet prostheses. Nineteen patients (14 female, mean age 64 years) who had undergone aortic valve replacement with 21 mm bileaflet valve prostheses (St. Jude Medical valve, n = 9, or CarboMedics valve, n = 10) were studied. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-1 and increased to 10 and 20 micrograms.kg-1.min-1 at 15-minute intervals. Under maximum stress, heart rate and cardiac output increased by 70% and 120%, respectively, and mean arterial blood pressure decreased by 9%. Pulsed-wave and continuous-wave Doppler studies were performed at rest and at the end of each stage. Velocity ratio, effective orifice area, performance index, and discharge coefficient of the valve were calculated, and peak and mean velocities and pressure drops across the prostheses were measured. Dobutamine infusion produced similar increases in cardiac output in all patients. Effective orifice areas, discharge coefficients, and performance indexes were comparable for the two valve groups both at rest and maximum stress. Transvalvular velocities and pressure drops were also similar in the two valve groups. Transvalvular pressure drops were also comparable in patients with large body surface area. Dobutamine stress echocardiography is useful in the evaluation of the hemodynamic performance of prosthetic heart valves. St. Jude Medical and CarboMedics 21 mm prostheses have equally favorable hemodynamic performances in most patients under conditions of high cardiac output.

Place of Video-thoracoscopy in Thoracic Surgical Practice

The advent of video-endoscopy revolutionizes the practice of surgery. Within a short span of time, video-assisted thoracic surgery (VATS) has become an acceptable approach to a wide range of thoracic procedures. The use of VATS as a diagnostic modality is now well established. For therapeutic procedures, VATS has also been generally accepted for the treatment of such conditions as primary spontaneous pneumothorax, loculated effusions, thoracodorsal sympathectomy, and resection of simple mediastinal cysts. Its roles in more complex procedures such as thymectomy and anatomic lung resections, however, remain poorly defined at present, even though the existing intermediate-term results are encouraging. VATS is still in evolution. Miniaturization of instruments promises to reduce access-induced trauma even further. On the other hand, attention to cost-containment is essential if VATS is to be applicable to patients in developing countries. Technology will continue to change. Carefully conducted clinical trials should precede the general acceptance of any new technology, no matter how attractive it may appear initially.AbstractThe advent of video-endoscopynrevolutionizes the practice of surgery. Within a short span of time,nvideo-assisted thoracic surgery (VATS) has become an acceptablenapproach to a wide range of thoracic procedures. The use of VATS as andiagnostic modality is now well established. For therapeuticnprocedures, VATS has also been generally accepted for the treatment ofnsuch conditions as primary spontaneous pneumothorax, loculatedneffusions, thoracodorsal sympathectomy, and resection of simplenmediastinal cysts. Its roles in more complex procedures such asnthymectomy and anatomic lung resections, however, remain poorly definednat present, even though the existing intermediate-term results arenencouraging. VATS is still in evolution. Miniaturization of instrumentsnpromises to reduce access-induced trauma even further. On the othernhand, attention to cost-containment is essential if VATS is to benapplicable to patients in developing countries. Technology willncontinue to change. Carefully conducted clinical trials should precedenthe general acceptance of any new technology, no matter how attractivenit may appear initially.n

Video-Assisted Thoracoscopic Thymectomy for Myasthenia Gravis

Video-assisted thoracoscopic surgery (VATS) provides a new approach to thymectomy. From June 1993 to December 1994, we performed a total of eight thymectomies for myasthenia gravis (MG). There were four male and four female patients with ages ranging from 9 to 76 years. Three of the eight patients had associated thymoma. We believe that complete thymectomy was accomplished in all cases by examination of the thymic bed and resected specimen. There was no mortality or intraoperative complications. The median postoperative hospital stay was 5 days (range, 2 to 37 days). One patient required ventilatory support postoperatively. Clinical improvement was observed in all patients after a mean follow-up of 10 months (range, 2 to 21 months). Compared with a comparable historical group of patients with MG who underwent transsternal thymectomy, the VATS group was associated with significantly less analgesic requirement and shortened hospital stay. We conclude that VAT thymectomy is technically feasible and is associated with a favorable postoperative course compared with the transsternal approach. We believe that complete thymectomy can be achieved by this approach. Further investigation with long-term follow-up is needed to further clarify the role of VAT thymectomy in thoracic surgery.

Micro-RNA and mRNA myocardial tissue expression in biopsy specimen from patients with heart failure

AIMSnThere is increasing evidence that changes in microRNA (miRNA) expression occur in chronic heart failure and these may be involved in the pathogenesis. In this study we have explored the expression of selected myocyte and fibroblast-related microRNAs and messenger RNAs (mRNAs) that are associated with hypertrophy, apoptosis and fibrosis in biopsy specimens from patients with relatively new onset heart failure compared to a group of patients without heart failure.nnnMETHODS AND RESULTSnMyocardial biopsy specimens taken from Chinese patients presenting with recent heart failure were compared with a group of patients without heart failure undergoing routine cardiac surgery (n=34). miRNAs (miR-1, -21, -23, -29, -30, -130, -133, -195, -199, -208, and -320) and corresponding mRNA expression were measured by real-time quantitative-PCR method. miR-1, -21, -23, -29, -130, -195 and -199 were significantly up-regulated in the heart failure group when compared to those without heart failure (all p<0.01). However, miR-30, -133, -208 and -320 were not significantly different. Related mRNAs (casp3, coll I, coll III and TGF) were also significantly up-regulated (all p<0.05) in the heart failure group.nnnCONCLUSIONnCertain selected microRNAs involved in apoptosis, hypertrophy and fibrosis are up-regulated in the myocardium of patients with a clinical history of heart failure compared to those without. These specific miRNAs may be the most suitable for circulating biomarkers in the early stages of chronic heart failure and possibly future therapeutic targets.