Population Pharmacokinetic Model-Based Evaluation of Standard Dosing Regimens for Cefuroxime Used in Coronary Artery Bypass Graft Surgery with Cardiopulmonary Bypass.

The purpose of this study was to investigate the population pharmacokinetics (PK) of cefuroxime in patients undergoing coronary artery bypass graft (CABG) surgery. In this observational pharmacokinetic study, multiple blood samples were collected over a 48-h interval of intravenous cefuroxime administration. The samples were analyzed by using a validated high-performance liquid chromatography (HPLC) method. Population pharmacokinetic models were developed using Monolix (version 4.4) software. Pharmacokinetic-pharmacodynamic (PD) simulations were performed to explore the ability of different dosage regimens to achieve the pharmacodynamic targets. A total of 468 blood samples from 78 patients were analyzed. The PK for cefuroxime were best described by a two-compartment model with between-subject variability on clearance, the volume of distribution of the central compartment, and the volume of distribution of the peripheral compartment. The clearance of cefuroxime was related to creatinine clearance (CLCR). Dosing simulations showed that standard dosing regimens of 1.5 g could achieve the PK-PD target of the percentage of the time that the free concentration is maintained above the MIC during a dosing interval (fTMIC) of 65% for an MIC of 8 mg/liter in patients with a CLCR of 30, 60, or 90 ml/min, whereas this dosing regimen failed to achieve the PK-PD target in patients with a CLCR of ≥125 ml/min. In conclusion, administration of standard doses of 1.5 g three times daily provided adequate antibiotic prophylaxis in patients undergoing CABG surgery. Lower doses failed to achieve the PK-PD target. Patients with high CLCR values required either higher doses or shorter intervals of cefuroxime dosing. On the other hand, lower doses (1 g three times daily) produced adequate target attainment for patients with low CLCR values (≤30 ml/min).

Population Pharmacokinetic Model for Vancomycin Used in Open Heart Surgery: Model-Based Evaluation of Standard Dosing Regimens.

The purpose of this study was to investigate the population pharmacokinetics of vancomycin in patients undergoing open heart surgery. In this observational pharmacokinetic study, multiple blood samples were drawn over a 48-h period of intravenous vancomycin in patients who were undergoing open heart surgery. Blood samples were analyzed using an Architect i4000SR immunoassay analyzer. Population pharmacokinetic models were developed using Monolix 4.4 software. Pharmacokinetic-pharmacodynamic (PK-PD) simulations were performed to explore the ability of different dosage regimens to achieve the pharmacodynamic targets. A total of 168 blood samples were analyzed from 28 patients. The pharmacokinetics of vancomycin are best described by a two-compartment model with between-subject variability in clearance (CL), the volume of distribution of the central compartment (V1), and volume of distribution of the peripheral compartment (V2). The CL and the V1 of vancomycin were related to creatinine CL (CLCR), body weight, and albumin concentration. Dosing simulations showed that standard dosing regimens of 1 and 1.5 g failed to achieve the PK-PD target of AUC0-24/MIC > 400 for an MIC of 1 mg/liter, while high weight-based dosing regimens were able to achieve the PK-PD target. In summary, the administration of standard doses of 1 and 1.5 g of vancomycin two times daily provided inadequate antibiotic prophylaxis in patients undergoing open heart surgery. The same findings were obtained when 15- and 20-mg/kg doses of vancomycin were administered. Achieving the PK-PD target required higher doses (25 and 30 mg/kg) of vancomycin.

Does preoperative screening with computed tomography of the chest decrease risk of stroke in patients undergoing coronary artery bypass grafting.

Background: Stroke is one of the most feared complications post coronary artery bypass with aortic calcifications being the commonest source of embolic stroke. The aim of our study was to determine the clinical impact and usefulness of routine use of plain chest computerised tomography to screen for aortic calcification on incidence of postoperative stroke in coronary artery bypass grafting (CABG) patients. Methods: This is a retrospective case-control study that included four hundred and five patients who underwent primary isolated CABG and had preoperative plain chest computerised tomography as a screening for aortic calcification. Aortic calcification was classified according to the area involved (ascending, arch, arch vessels and descending aorta) and the pattern of calcification. Patients were divided into two groups according to the incidence of postoperative stroke and the aortic calcification distribution was compared between the two groups. Stroke predictors were studies using univariate and multivariate regression analysis. Results: Fourteen patients (3.5%) developed postoperative stroke. There was no difference in preoperative and operative characteristics between patients who developed postoperative stroke and those who did not, except for the history of preoperative stroke or transient ischemic attack (TIA) that was higher in the group who developed postoperative stroke (50.00% vs. 6.19%, P<0.001). Patients who developed postoperative stroke had higher percentage of aortic root calcification (78.57% vs. 64.18%), ascending aortic calcification (28.57% vs. 19.07%) and descending aortic calcification (85.71% vs. 73.71%) but none of them reached statistical significance. History of preoperative stroke or TIA was the only significant predictor of postoperative stroke using both univariate and multivariate regression models. Conclusions: Our study showed the importance of preoperative computed tomography (CT) scan of the chest as a screening tool as it detected a high prevalence of aortic calcification in our patients. However, its impact on prevention of postoperative stroke needs to be investigated further in future prospective studies.

Hybrid Thoracic Aortic Repair and Aortic Valve-In-Valve Replacement for Chronic Type A Dissection.

We describe a case of hybrid total thoracic aortic repair and valve-in-valve transcatheter aortic valve replacement in a high-risk patient with complicated chronic type A dissection and severe prosthetic aortic stenosis. The patient underwent a three-stage-procedure including aortic arch debranching, thoracic endovascular aortic repair of the ascending aorta, aortic arch and descending thoracic aorta, and direct aortic valve-in-valve replacement using transcatheter heart valve. The details of the procedures are described with a discussion of the challenges and the decision-making process.

Results of Surgical Ablation for Atrial Fibrillation in Patients with Rheumatic Heart Disease.

Background: There is conflicting evidence regarding the success of the Maze procedure to restore sinus rhythm in patients with rheumatic heart disease. Hence, the aim of our study was to describe the results of surgical ablation for atrial fibrillation in patients with rheumatic heart disease undergoing cardiac surgery. Methods: This is a retrospective study that included adult patients with rheumatic heart disease who underwent surgical ablation for atrial fibrillation. The ablation lesions were performed using monopolar radiofrequency ablation in all patients. Results: Fifty-seven consecutive patients were included in the study. Cox Maze IV was performed in 44 patients (77%), while left-sided surgical ablation was performed in 10 patients (17%) and pulmonary vein isolation in 3 patients (5%). The percentage of patients who were in sinus rhythm on discharge, at 1-month, at 3-months, 6-months and 12-months follow up were 56%, 54%, 52%, 56% and 46% respectively. Complete heart block occurred in 21 patients (44%), but only 15 of them (26%) required permanent pacemaker insertion. Freedom from composite endpoint of death, stroke, and readmission for heart failure was 78% at one-year follow up. Conclusion: Despite the suboptimal rates of sinus rhythm at the intermediate and long term follow up, surgical ablation of atrial fibrillation in patients with rheumatic heart disease should continue to be performed. Continuation of Class III antiarrhythmic medications and early intervention for recurrent atrial fibrillation is crucial to the success of this procedure and for maintenance of higher rates of sinus rhythm at intermediate and long-term follow up.

Serum level of prophylactic antibiotics in cardiac surgery and its implication on surgical site infection (SSI).

BACKGROUND: Surgical site infection in cardiac surgery is still common despite applying preoperative antibiotic prophylaxis as per guidelines. Therefore, the aim of our study was to assess the relationship between perioperative antibiotics serum levels and the incidence of surgical site infection. METHODS: This is a prospective study that included all adult patients who underwent elective coronary artery bypass grafting between June and December 2018. The serum antibiotics levels were measured at 4 different time points. The patients were divided into two groups: The group who developed surgical site infection and the group who did not develop surgical site infection. The serum antibiotics levels were compared between the two groups. RESULTS: Eighty-seven consecutive patients were enrolled in the study. The overall rate of infection was 17.95% (14/78 patients). High pre-operative HbA1C levels were associated with a higher rate of SSI (SSI 8.46 ± 2.23 vs no SSI 7.28 ± 1.82, P = 0.04). Patients who developed surgical site infection had longer intervals between administration of prophylactic antibiotics and different parts of the procedure than those who did not develop infection T2 (SSI 3.09 ± 1.12 vs no SSI 2.32 ± 0.98, P = 0.004), T3 (SSI 5.74 ± 1.69 vs no SSI 4.68 ± 1.83, P = 0.024) and T4 (SSI 7.35 ± 1.97 vs no SSI 6.01 ± 2.11, P = 0.015). CONCLUSION: Prolonging different parts of cardiac surgery procedures could lead to higher risk of infection and better timing of intra-operative re-dosing of prophylactic antibiotics could be guided by measuring intra-operative serum concentrations of these antibiotics.

The effect of using the minimized cardio-pulmonary bypass Systems for Coronary Artery Bypass Grafting in diabetic patients.

INTRODUCTION: Multiple studies have shown a decrease in the inflammatory response with minimized bypass circuits leading to less complications and mortality rate. On the other hand, some other studies showed that there is no difference in post-operative outcomes. So, the aim of this study is to investigate the clinical benefits of using the Minimized cardiopulmonary Bypass system in Coronary Artery Bypass Grafting and its effect on postoperative morbidity and mortality in diabetic patients as one of the high-risk groups that may benefit from these systems. METHODS: This is a retrospective study that included 114 diabetic patients who underwent Coronary artery bypass grafting (67 patients with conventional cardiopulmonary bypass system and 47 with Minimized cardiopulmonary bypass system). The patients' demographics, intra-operative characteristics and postoperative complications were compared between the two groups. RESULTS: Coronary artery bypass grafting was done on a beating heart less commonly in the conventional cardiopulmonary bypass group (44.78% vs. 63.83%, p = 0.045). There was no difference between the two groups in blood loss or transfusion requirements. Four patients in the conventional cardiopulmonary bypass group suffered perioperative myocardial infarction while no one had perioperative myocardial infarction in the Minimized cardiopulmonary bypass group. On the other hand, less patients in the conventional group had postoperative Atrial Fibrillation (4.55% vs. 27.5%, p = 0.001). The requirements for Adrenaline and Nor-Adrenaline infusions were more common the conventional group than the Minimized group. CONCLUSION: The use of conventional cardiopulmonary bypass for Coronary Artery Bypass Grafting in diabetic patients was associated with higher use of postoperative vasogenic and inotropic support. However, that did not translate into higher complications rate or mortality.

Surgical mitral valve replacement using direct implantation of Sapien 3 valve in a patients with severe mitral annular calcification without adjunctive techniques, a case report.

BACKGROUND: Mitral annular calcification (MAC) occurs represents a challenge to surgeons during mitral valve (MV) surgery with increased perioperative risk. CASE PRESENTATION: We describe a challenging case of an elderly female patient with multiple comorbidities who presented with symptoms and signs of heart failure with a previous history of mechanical aortic valve replacement 15 years prior to presentation. Echocardiogram showed severe mitral stenosis and regurgitation with severe calcification of the mitral annulus. Given her high-risk profile and unavailability of suitable percutaneous therapeutic options we decided to replace her mitral valve with Sapien 3 valve under direct exposure. The case describes the technical details for the valve implantation and demonstrates the viability of this option in high risk surgical patients without the need for adjunct techniques like predilatation, additional supporting sutures or patches with a review of the literature on open surgical implantation of Sapien 3 valve. CONCLUSION: Direct open surgical implantation of Sapien 3 valve can be implanted safely in patients with severe MAC, without predilatation and without the use of other adjunctive techniques like fixation sutures or patches.