Reactive molecular dynamics simulations of lithium-ion battery electrolyte degradation

The development of reliable computational methods for novel battery materials has become essential due to the recently intensified research efforts on more sustainable energy storage materials. Here, we use a recently developed framework allowing to consistently incorporate quantum-mechanical activation barriers to classical molecular dynamics simulations to study the reductive solvent decomposition and formation of the solid electrolyte interphase for a graphite/carbonate electrolyte interface. We focus on deriving condensed-phase effective rates based on the elementary gas-phase reduction and decomposition energy barriers. After a short initial transient limited by the elementary barriers, we observe that the effective rate shows a transition to a kinetically slow regime influenced by the changing coordination environment and the ionic fluxes between the bulk electrolyte and the interface. We also discuss the impact of the decomposition on the ionic mobility. Thus, our work shows how elementary first-principles properties can be mechanistically leveraged to provide fundamental insights into electrochemical stability of battery electrolytes.

Effect of ischemic postconditioning on myocardial protection in patients undergoing coronary artery bypass grafting surgery with cardiopulmonary bypass

INTRODUCTION

Reperfusion injury is a well-known phenomenon following restoration of the coronary circulation after coronary artery bypass grafting (CABG) that impairs myocardial function. In order to control the severity of this injury, we aimed to investigate the effect of a new conditioning strategy namely ischemic postconditioning (IPOC) along with controlled aortic root reperfusion (CARR) on myocardial protection in CABG surgery with cardiopulmonary bypass.

METHODS

In a doubled blind clinical trial study, 51 patients undergoing first-time elective CABG were randomly divided in three groups: CARR, IPOC, and combination of IPOC and CARR. At the end of procedure and just before aortic cross-clamp removal, reperfusion was started as following: In CARR-receiving groups, the reperfusion was started with low perfusion pressures for 10 minutes, and in IPOC-receiving groups, three cycles of 1 minute episodes of ischemia separated by 1 minute episodes of reperfusion was applied as postconditioning protocol. Left ventricular ejection fraction (EF) (by echocardiography), inotrope requirement index, and myocardial arrhythmias were measured up to 72 hours after operation.

RESULTS

Echocardiography revealed that the recovery of EF after operation in IPOC group was significantly higher than those of two other groups (P < 0.05). Inotropic support requirement was significantly lower in IPOC groups. In addition, the incidence of atrial and ventricular arrhythmias after opening of aortic clamp and in intensive care unit (ICU) as well as recovery time of cardiac rhythm upon reperfusion were lowered by administration of IPOC, as compared with CARR group.

CONCLUSION

The study suggests that IPOC may provide clinical benefits against reperfusion injury in patients undergoing CABG surgery and maintain the post ischemic left ventricular performance.

Radiofrequency ablation for treatment of atrial fibrillation

INTRODUCTION

Atrial Fibrillation (AF) is the most common cardiac arrhythmia which represents a major public health problem. The main purpose of this research is to evaluate the Radiofrequency (RF) ablation effects in the patients with chronic AF scheduled for cardiac surgery because of different heart diseases.

METHODS

The descriptive and prospective study was conducted on 60 patients with AF scheduled for surgery along with RF ablation. The data were collected by questionnaire and included: patients' age, sex, NYHA class, operation type, past medical history, type and cause of valvular heart disease, preoperative ECG (electrocardiogram), duration of surgery, clamping time, cardiopulmonary bypass, and RF ablation time. RF ablation was followed by the main operation. The follow up examination, ECG, and echocardiography were performed 3 and 6 months after operation.

RESULTS

The mean age of patients was 48±10 years (18-71 years). Forty one patients had permanent AF and 19 had the persistent AF. The left ventricular ejection fraction was 48.27±9.75 percent before operation, and reached to 56.27±7.87 percent after the surgery (P<0.001). The mean NYHA class before the surgery was 2.83±0.68 which decreased to 1.34±0.46 6 months after the surgery with RF ablation (P<0.001). One patient (1.6%) died after surgery. Complete relief and freedom from AF recurrence was observed in 70% of patients in the mean follow up in 7 months after the surgery. The sinus rhythm with efficient atrial contraction was established in 100% of discharged patients.

CONCLUSION

RF ablation is an effective procedure to cure atrial fibrillation in patients undergoing cardiac surgeries.

Coronary risk factors in patients underwent coronary artery bypass grafting

Coronary Artery Disease (CAD) risk increases with increasing number of risk factors. This study was aimed to assess different coronary risk factors among Coronary Artery Bypass Grafting (CABG) surgery patients. A total of 700 patients younger than 45 or older than 65 years and underwent CABG in Tabriz Shahid Madani Heart Center since 2003 to 2007 were enrolled. We examined the probable differences of CAD risk factors between male and female groups and age groups. We also assessed the change of risk factors presentation in last 5 years. There was not significant difference between risk factor numbers in <45 and >65 years groups, but smoking and dyslipidemia was more prevalent in patients < 45 than > 65 years old. Hypertension and diabetes mellitus was more prevalent in patients > 65 old than < 45 years old; also differences were found between males and females patients, so that dyslipidemia, diabetes and hypertension were more prevalent in women than men. Some risk factors were recognized as acting more on one gender than the other. Also, the majority of patients have one or more risk factors, but different age and gender groups may have different risk factors that suggest the need for exact programming for appropriate prophylactic and therapeutic interventions in all groups.

Intracoronary shunt in off-pump coronary artery bypass graft

This study was performed to compare the early postoperative results of off Pump Coronary Artery Bypass Graft (OPCABG) with or without using Intra Coronary Shunt (ICS). We randomized 208 patients scheduled for OPCABG into shunt group (group 1, n = 104) and no-shunt group (group 2, n = 104). The two groups were well matched according to the age, gender, angina class, New York Heart Association (NYHA) functional class, or operative priority and disease severity. Peri- and post-operative changes in electrocardiography, wall motion abnormality in echocardiography, rate of myocardial infarction, mortality, morbidity, cardiac enzymes and ICU stay were recorded. There was no significant difference between two groups in changes of electrocardiography, myocardial infarction, left ventricular ejection fraction (LVEF), in hospital mortality and ICU stay but Creatine Kinase Myocardial Band (CK-MB) enzyme was higher in no shunt group, while troponin-I was increased in shunt group. Preoperative LVEF was higher in no-shunt group, but postoperative LVEF was higher in shunt group (p > 0.05). Also, the change of LVEF before and after operation in each group was not significant. Using intracoronary shunt in off pump coronary artery bypass graft leads to less change in cardiac enzymes but had no effect on perioperative and postoperative myocardial infarction, LVEF, mortality and morbidity.

Outcomes of coronary artery bypass grafting in patients with a history of opiate use

This study aimed at evaluating the outcome of CABG in patients with a history of opiate use. Two hundred male patients, underwent CABG surgery, were evaluated and followed up for 6 months. The patients classified as Group P (with Previous history of opiate use) and Group N (with No history of opiate use). The characteristics and 6-month outcomes were compared between the two groups. Patients in group P further categorized into two subgroups of active and non-active abusers. Two hundred male-patients enrolled in the study, 23 (11.5%) patients had a history of opiate abuse. Nine (4.5%) patients were past users and 14 (7%) cases were current users. There were no significant differences regarding the age, history of hypertension, smoking, ejection fraction before and 6 months after CABG, duration of hospital stay, complications of surgery and function class (p<0.05). The level of patients obeys from physician's medical, nutritional and activity recommendations after CABG was significantly lower for current opiate users. Also, the need for readmission after CABG due to cardiac complications was independently higher in current opiate users. Carrying out the educational programs to correct the misconception about the beneficial effects of illicit drugs on cardio-vascular disease makes sense.

A case of Aspergillus fumigatus mediastinitis after heart surgery in Madani Heart Center, Tabriz, Iran

Reported here is the case of a 60-year-old male diabetic patient with mediastinitis caused by Aspergillus fumigatus following an open heart surgery that was successfully treated. A review of literature revealed that A. fumigatus as a cause of mediastinitis has been rarely described. Aspergillus infection should be considered in the differential diagnosis of mediastinitis after cardiac surgery, especially in a clinical setting of unexplained sepsis or nonhealing wound infection despite apparently adequate treatment.