[Comparison of myotomy and coronary artery bypass grafting in surgical treatment of symptomatic left anterior descending myocardial bridges]

Objective: To compare the effect of myotomy and coronary artery bypass grafting (CABG) to treat symptomatic myocardial bridges (MBs) of the left anterior descending artery (LAD). Methods: From January 2009 to December 2017, a total of 54 eligible patients [34 males, 20 females, with a median age of 60 (51, 64) years old] with symptomatic MBs of LAD who underwent myotomy (31 patients) or CABG (23 patients) at the Department of Cardiovascular Surgery of Zhongshan Hospital, Fudan University were included in the study. Surgical effect of the two groups were compared and multivariate logistic regression models were used to analyze the risk factors of major adverse cardiac events (MACE). Results: No significant differences between the two groups were observed with respect to age, gender, risk factors of coronary artery disease (CAD), symptoms, angiographic findings of MBs and preoperative cardiac status, and 0 surgery-associated death was observed. Among the 31 myotomy patients, 4 patients underwent off-pump myotomy (including one patient who underwent urgent conversion from off-pump to on-pump surgery due to massive hemorrhaging secondary to the right ventricular perforation), and the remaining 27 cases received myotomy under cardiopulmonary bypass with cardiac arrest. All 23 bypass surgery patients underwent off-pump CABG surgery with in situ left internal mammary artery (LIMA) grafting to the distal LAD. After LIMA grafting, the median graft flow was 14 (11, 20) ml/min. During a median follow-up of 26 months, 11 patients developed MACEs (7.4% for myotomy vs 40.9% for bypass surgery, P=0.007). Surgical strategy (CABG surgery vs myotomy) was an independent risk factor for MACE (OR=3.681, 95% CI: 1.812-8.685, P=0.011). Compared with myotomy, CABG surgery had a significantly higher incidence of adverse angiographic results (3.7% of residual compression vs 40.9% of LIMA graft failure, P=0.003). Among 10 CABG surgery patients with LAD-MBs and proximal coronary obstruction, all LIMA grafts were patent, though one case reported recurrent angina pectoris 2 years after the surgery which was relieved after drug therapy. Conclusions: For patients with symtomatic LAD-MBs, myotomy may be associated with favorable mid-term outcomes and angiographic results. However, CABG surgery should be recommended for those with concomitant proximal obstruction of LAD.

[Impact of discontinuation of aspirin and clopidogrel before off-pump coronary artery bypass grafting on postoperative bleeding and transfusion requirement]

Objective: To investigate the influence of different discontinuation time of aspirin and clopidogrel before off-pump coronary artery bypass grafting (OPCABG) on postoperative bleeding and blood products transfusion requirement. Methods: Three hundred and fifty-three coronary artery disease patients who underwent OPCABG from January 2017 to January 2018 at Department of Cardiac Surgery, Zhongshan Hospital, Fudan University were retrospectively analysed. There were 268 males and 85 females, aged (66.0±9.1)years. All patients were divided into three groups: (1) guideline-recommended group: patients who discontinued clopidogrel for >5 days without discontinuing aspirin before surgery; (2) without discontinuing group: patients who discontinued clopidogrel for ≤5 days without discontinuing aspirin before surgery; (3) discontinuing group: patients who discontinued clopidogrel for >5 days with discontinuing aspirin before surgery. Postoperative bleeding recorded as chest tube drainage (CTD) volume and blood products transfusion requirement and perioperative complications were recorded. CTD volumes within 12 hours after surgery between groups were compared by Mann-Whitney U tests, CTD volumes after 12 hours postoperatively were compared by repeated measures analysis of variance and blood products transfusion and complications incidence were compared by χ(2) test or Fisher's precise test. Results: The 12 hours CTD volumes of guideline-recommended group, without discontinuing group, discontinuing group after surgery were 280(153) ml (M(Q(R))), 291(229) ml, 225(161) ml, respectively. There were no significant differences in postoperative 12 hours CTD volumes (P=0.865), red blood cells transfusion incidence (χ(2)=2.626, P=0.149) and fresh frozen plasma (FFP) transfusion incidence (χ(2)=1.258, P=0.324) between guideline-recommended group and without discontinuing group. However, the 12 hours CTD volumes were significantly higher in guideline-recommended group patients compared with disconutinuing group patients (U=5 247, P=0.002). No significant differences were observed in red blood cells (χ(2)=0.182, P=0.757) and FFP (χ(2)=0.083, P=0.839) transfusion rate between these two groups. Repeated measures analysis of variance indicated that when patients began to take antiplatelet drugs (aspirin and clopidogrel) after 12 hours postoperatively, the change of CTD volumes beyond 12 hours after surgery didn't differ either between guideline-recommended group and without discontinuing group (F=0.019, P=0.941) or between guideline-recommended group and discontinuing group (F=2.447,P=0.113). Besides, the incidence of perioperative arrhythmia was significantly higher in guideline-recommended group patients compared with without discontinuing group patients (4.8% vs. 0, χ(2)=5.073, P=0.038). Conclusions: OPCABG patients who discontinued aspirin before surgery had lower postoperative 12 hours CTD volumes but similar blood products transfusion rate and CTD volumes beyond 12 hours postoperatively compared with patients adhering to the current guideline-recommended protocol. And for patients who discontinued clopidogrel for ≤5 days, postoperative CTD volumes and blood products transfusion requirement were similar but the incidence of perioperative arrhythmia was significantly lower compared with guideline-treated patients.

[Myocardial revascularization among patients with severe left ventricular dysfunction: a comparison between on-pump beating-heart and off-pump coronary artery bypass grafting]

Objective: To evaluate the impacts of an on-pump beating-heart versus an off-pump coronary artery bypass grafting (CABG) technique for surgical revascularization on the early clinical outcomes in patients with a left ventricular ejection fraction (EF) of 35% or less. Methods: A total of 216 consecutive patients with an echocardiographic estimated EF of 35% or less who underwent non-emergency, primary, isolated CABG from January 2010 to December 2014 at Department of Cardiovascular Surgery, Zhongshan Hospital, Fudan University were included in this study and were divided into either an OBCAB group (patients who received on-pump beating-heart CABG surgery, n=88) or an OPCAB group (patients who received off-pump CABG surgery, n=128). The early clinical outcomes were investigated and compared. The outcomes were compared between groups by t-test, χ² test or Fisher's exact test, when appropriate. Results: No significant differences emerged between the two groups in baseline characteristics of the entire cohort except for more patients with diabetes and a larger left ventricular endo-diastolic diameter in the OBCAB group. Patients in the OBCAB group compared to the OPCAB group had a similar in-hospital mortality (3.4% vs. 4.7%, P= 0.741). Mean EF, as measured preoperatively and early postoperatively (before discharge), significantly improved from (31.0±2.8)% to (35.6±2.9)% (t=10.61, P=0.000) in the OBCAB group and from (31.0±2.9)% to (34.8±3.3)% (t=9.68, P=0.000) in the OPCAB group, respectively. The improvement of mean LVEF in the OBCAB group was significantly higher than that in the OPCAB group ((4.7±0.2)% vs. (3.6±0.3)%, t=29.53, P=0.000). Patients in the OBCAB group compared to the OPCAB group had a significant higher early postoperative EF ((35.6±2.9)% vs.(34.8±3.3)%, t=1.892, P=0.034) but shared a similar baseline EF ((31.0±2.8)% vs. (31.0±2.9)%, t=0.012, P=0.930). Patients in the OBCAB group compared to the OPCAB group received a greater number of grafts and an increased amount of drainage during the first 24 h (3.7±0.8 vs. 2.8±0.6, t=9.442, P=0.000; (715±187) ml vs. (520±148) ml, t=8.544, P=0.000, respectively), without evidence of worse in-hospital mortality or major postoperative morbidity. Conclusion: The on-pump beating-heart technique may be an acceptable alternative to the off-pump technique for surgical revascularization in patients with an estimated EF of 35% or less.

[Comparison of anterolateral minithoracotomy versus partial upper hemisternotomy in aortic valve replacement]

OBJECTIVE

To compare the results of aortic valve replacement through anterolateral minithoracotomy (RT) and partial upper hemisternotomy (PS) approaches.

METHODS

This was a retrospective, observational, cohort study of collected data on 297 patients undergoing isolated primary aortic valve replacement between July 2009 and March 2016 at Department of Cardiovascular Surgery, Zhongshan Hospital, Fudan University. There were 174 male and 123 female patients, aging from 15 to 73 years with a mean age of (51±13) years. Of these, 132 were performed through right RT and 165 through PS. Outcomes of the two groups were compared by t test, t' test, rank-sum test and χ(2) test, respectively.

RESULTS

The overall in-hospital mortality was 1.7% (5/297), with no difference between the 2 groups (3.0%, 4/132 vs. 0.6%, 1/165, P=0.175 ). Patients in the RT group had longer cardiopulmonary bypass ((92±27) minutes vs. (76±18) minutes, t'=5.848, P=0.000)and crossclamping ((56±21) minutes vs. (43±12) minutes, t'=6.333, P=0.000)times. Three patients in the RT group and two patients required intraoperative conversion. Patients by way of RT was associated with a lower incidence of blood transfusions (20.4% vs. 39.4%, χ(2)=12.303, P=0.001) and less drainage (250 (307) ml vs. 570 (370) ml, Z=8.161, P=0.000). In addition, patients in RT group had a shorter postoperative length of stay (5(4) days vs. 9(10) days, Z=4.548, P=0.000).

CONCLUSIONS

Aortic valve replacement via RT and PS are both safe and feasible. The approach through PS is associated with better exposure, more extensive indication for surgery, and more suitable to heart centers which intend to carry out miminally invasive aortic valve replacement. While, for an experienced surgeon, the approach through right RT is worthy of clinical selective application for patients concern more about good cosmetic result, and patients have faster recovery by avoid sternotomy through RT approach.

An integrated model of substrate clogging in vertical flow constructed wetlands

This paper presents an integrated model of substrate clogging in a vertical flow constructed wetland (VFCW). The model simulates the reduction of pore space in the wetland substrate due to combined influences of various physical, biogeochemical and plant-related processes. A series of experiments based on laboratory-scale VFCWs were conducted to examine and measure key parameters related to clogging of the wetland substrate during operation under different conditions. The model was then validated using data collected from the experiments. The results showed that the model was able to replicate the clogging phenomenon as observed in the experiments, in particular, the characteristic clogging time. The model also predicted well individual contributions to clogging by accumulated inert suspended solids, microbial biomass and plant root materials during the wetland operation. Although the validation was based on the laboratory data, the results indicated that the model describes well the processes underlying the clogging and has the potential to become a tool for assessing the performance of prototype CWs in relation to clogging at both the design and operation stages.

Superconductivity induced by Ni doping in SmFe(1-x)Ni(x)AsO

Superconductivity with a T(c) of about 10 K is observed in the Ni-doped SmFe(1-x)Ni(x)AsO system. The measurements of resistivity and magnetic susceptibility show that the spin-density wave (SDW) order is quickly suppressed with increasing Ni content, and superconductivity emerges as x≥0.04. T(c)(mid) shows a maximum of 10.8 K at x = 0.06, and it drops to lower than 2 K as x>0.12. Meanwhile, the upper critical field (H(c2)(0)) is estimated to be about 40 T for the optimally-doped sample (x = 0.06). The normal state thermopower is negative for all the Ni-doped samples, indicating that an electron-type charge carrier dominates in the transport properties. Moreover, the magnitude of the room-temperature thermopower increases with increasing Ni content, and then shows a broad peak around x = 0.06. We found that there is an obvious correlation between the anomalously enhanced thermopower and superconductivity. A phase diagram is derived based on the transport measurements and a dome-like T(c)(x) curve is established.

[Pharmacokinetic analysis of enterohepatic circulation of piroxicam in rabbits]

The concentration (c)-time (t) curves of piroxicam showed double peaks following iv 10 mg dose to 4 rabbits. A new mathematical model of enterohepatic circulation was proposed to explain this double-peak phenomenon and showed good agreement with data. This model provides not only the common pharmacokinetic parameters: T1/2 = 1.12 +/- 0.32 h, V1 = 0.64 +/- 0.12 L, AUC = 34.7 +/- 7.8 micrograms.h-1.ml-1, but also the parameters of enterohepatic circulation of piroxicam: the cycling amount of drug Db = 3.9 +/- 1.4 mg, reabsorption fraction Fb = 0.50 +/- 0.04, reabsorption rate constant Ka = 2.55 +/- 0.50 h-1. It is indicated in this study that enterohepatic circulation results in a 20% average increase of the effective amount of piroxicam.