Haider Zaman

Off-Pump Coronary Artery Bypass Surgery: Analysis of 5-Year Experience

We retrospectively evaluated the perioperative results of off-pump coronary artery bypass surgery performed in our center. Over a 5-year period, 520 patients were operated off-pump through a median sternotomy with the aid of a cardiac stabilizer and retractor. A total of 1,117 distal anastomoses were made with a mean of 2.2 ± 1.0 bypass grafts per patient. Only 12 patients (2.3%) required conversion to cardiopulmonary bypass, while 10 patients (1.9%) were re-operated for bleeding or graft failure. Perioperative myocardial infarction occurred in 10 patients (1.9%), and postoperative stroke in 3 patients (0.6%). The overall operative mortality was 2.5%, while the rate for the 48 patients who had previous bypass surgery was 2.1%. The results show that off-pump coronary surgery produces low mortality and morbidity, even in the treatment of multivessel disease or high-risk patients.

Optimization of the mechanical properties of abaca fibre-reinforced high impact polystyrene (HIPS) composites using Box-Behnken design of experiments

Mechanical properties of polymer composites are influenced by many factors such as the types of fibres, the types of polymer matrix, the additives used and the adhesion between fibres and polymer matrix. To improve the interfacial adhesion between HIPS matrix and abaca fibres, a study of the optimum use of a coupling agent (MAH) and impact modifier is presented in this paper. Abaca fibre reinforced high impact polystyrene (HIPS) composites were produced with different fibre loadings (30,40 and 50 wt.%), different compositions of coupling agent, maleic anhydride (MAH) (1, 2 and 3 wt.%) and different compositions of impact-modifier (4, 5 and 6 wt.%). A response surface methodology using Box-Behnken design was used in the design of experiments and analysis of results. Statistical analysis of mechanical properties gave very satisfactory model accuracy, because the coefficient of determinance was 0.9817 for impact strength, 0.9789 for tensile strength, 0.9672 for tensile modulus, 0.9700 for flexural strength, and 0.9747 for flexural modulus. In this study, a loading of abaca fibre of 36.76 wt.%, maleic anhydride 3 wt.%, and impact modifier 4 wt.% led to optimum individual impact strength. On the other hand, optimum individual tensile strength and tensile modulus were achieved when the loading of abaca fibre was close to 40.76 wt.%, maleic anhydride 3 wt.% and impact modifier 6 wt.%, but the optimum individual flexural strength and flexural modulus were found when the loading abaca fibre was close to 40.03 wt.%, maleic anhydride 3 wt.% and impact modifier 4 wt.%.

Total arterial myocardial revascularization: analysis of initial experience

BACKGROUND Total arterial myocardial revascularization is an attempt to overcome the problems of late vein graft atherosclerosis, occlusion and need for coronary re-operations. Despite increasing evidence of efficacy, the use of arterial conduits has not been accepted as a primary practice in most of the centers in Pakistan for various reasons. We analyze our initial experience to assess the feasibility of total arterial revascularization as a primary strategy in patients requiring first time coronary artery bypass grafting. METHODS Two hundred patients undergoing first time CABG at our institution, from January 2000 to April 2001, were studied. Group 1 consisted of 100 patients undergoing total arterial revascularization (using bilateral internal thoracic and radial arteries) and Group 2 consisted of 100 patients undergoing conventional CABG (using one internal thoracic artery and supplemental veins). Thirty-day mortality and early morbidity with particular reference to resternotomy for bleeding, cerebrovascular accidents, renal failure, and sternal dehiscence were the main outcome measures. RESULTS Patients in Group 1 were younger (56.2±10.4 vs. 60.3±9.8 years; P<0.001), had lower Parsonnet scores (4.8±0.4 vs. 9.6±1.8; P<0.001), and had better left ventricular function. Both groups received a similar number of grafts. The percentage of patients undergoing total arterial revascularization rose from 20% in the first three months to over 65% in the three later three-month periods. Overall 30-day mortality was 1.5%, one patient (1%) in Group 1 and two patients (2%) in Group 2. There was a similar incidence of postoperative complications and length of median postoperative stay in both groups. CONCLUSION Total arterial revascularization can be adopted as a primary strategy in most patients undergoing CABG with no increase in mortality or morbidity.

Surgical Repair of post-infarction ventricular septal rupture: Determinants of operative mortality and survival outcome analysis

Background and Objective: Ventricular septal rupture (VSR) is one of the fatal complications of myocardial infarction (MI). Surgery provides the maximum survival benefit. Our objective was to investigate the risk factors of surgical mortality and to do the survival analysis in the past six years at our hospital. Methods: All the patients operated at CPE Institute of Cardiology Multan Pakistan, between 2009 and 2015 for repair of post MI VSR were analysed retrospectively for demographics, comorbidities, operative and post operative outcomes. The primary outcome was 30 days mortality. The follow up was done till April 2017 and the follow up data was obtained from hospital records and by telephoning the patients. SPSS was used for statistical analysis. P value < 0.05 was considered significant. Results: A total of 31 patients were operated for VSR repair with a mean age of 57.19±7.73 years. Eighteen patients also had a concomitant coronary artery bypass grafting (CABG). The operative mortality in this series was 25.8% Univariate analysis showed that pre-operative ejection fraction (E.F) (p value 0.010) and cardiogenic shock (p value 0.031) were a significant risk factors for operative mortality while on logistic regression analysis only the cardiogenic shock was found to be an independent risk factor for operative mortality with the odds ratio of 2.17. Low ejection fraction only acted as a confounding variable. The mean survival at six years was 34 months with a survival rate of 28.6%. The additional CABG did not confer any survival benefit. Conclusion: The patients in cardiogenic shock pre-operatively have a high operative mortality. Low ejection fraction (E.F) acts as a confounding factor. Concomitant CABG does not confer any survival benefit.

Risks and benefits of giving early Aspirin within 6 hours of CABG: A retrospective analysis

Background & Objective: Antiplatelet drugs are frequently used after coronary artery bypass graft (CABG) surgery to prevent venous graft occlusion. The fear of bleeding complications prevents them to be given early post operatively, which is the time when antiplatelets use confers maximum benefit. Our objective was to determine the effect and influence of early aspirin therapy on fatal and nonfatal bleeding complications and blood requirements after coronary bypass surgery (CABG). Methods: The patients who only underwent coronary artery bypass surgery for the first time in the past three years and did not have any bleeding diathesis were retrospectively analyzed from the cardiac surgery database of CPEIC Multan. The patients either received aspirin within six hours of CABG or had it given after 12 hours. The patients were analyzed for mean blood loss and number of blood units transfused. SPSS was used for statistical analysis. P value < 0.05 was considered significant. Results: Total 281 patients received aspirin within six hours while 326 patients did not. Mean blood loss in early aspirin group was 727ml as compared to 767ml in the other group (p value 0.74). The median number of blood units transfused was 2 (p value 0.98). Our results did not show any statistical difference in both the groups. Conclusion: Aspirin can safely be given early after CABG without the fear of bleeding complications thus conferring the advantage of increased graft patency.

Off-Pump Coronary Revascularization preserves Renal Function in patients with Preoperative Non-Dialysis dependent renal dysfunction - A Prospective, Randomized Study

The off-pump coronary artery bypass operation (OPCAB) is a relatively new surgical procedure, which avoids the use of cardiopulmonary bypass and is intuitively considered renoprotective in patients with preoperative normal renal function. However, no prospective, randomized study has been done so far to show whether these benefits may also apply to patients with preoperative non-dialysis dependent renal dysfunction. This first ever prospective, randomized, controlled trial was performed in 50 patients (45 men, mean age 51.2±4.8 yrs) with preoperative nondialysis dependent renal insufficiency, undergoing first-time elective coronary artery bypass grafting. Patients were randomly assigned to conventional revascularization with cardiopulmonary bypass (on-pump) or beating heart revascularization (off-pump). Glomerular and tubular functions were assessed upto 48 hrs postoperatively. There were no deaths, strokes or myocardial infarctions in either group. Glomerular function as assessed by creatinine clearance and the urinary microalbumin/creatinine ratio was significantly worse in the on-pump group (p=0.0003 and p=0.008, respectively). Renal tubular function was also significantly impaired in the on-pump group as assessed by the increased N- acetyl glucosaminidase activity (p=0.021). Six patients in the on-pump group developed acute renal failure requiring renal support compared with one in the off-pump group although statistically the comparison was not significant (p=0.098). This study suggests that off-pump coronary artery bypass surgery reduces the likelihood of acute renal failure in patients with preoperative non-dialysis dependent renal dysfunction and thus shortens postoperative intensive care and length of hospital stay.

Differential Scanning Calorimetry (DSC) Analysis of Abaca Fibre (Musa Textile Nee) Reinforced High Impact Polystyrene (HIPS) Composites

Differential scanning calorimetry (DSC) was used to study the thermal behaviour of abaca fibre reinforced high impact polystyrene (HIPS) composites. Thermal analysis is based upon the detection of changes in the heat content (enthalpy) and the glass transition temperature (Tg) of optimum condition of abaca fibre reinforced HIPS composites. In this research, glass transitions temperature (Tg) of neat HIPS occurred below the Tg of optimum condition of composites as the temperature of an amorphous state. The endothermic peak of composites was in to range 430-435°C including neat HIPS and it observed that enthalpy of abaca fibre reinforced HIPS composites yielded below the neat HIPS 748.79 J/g.