Comparison of the effects of coronary artery anastomosis training between senior and junior surgeons.

OBJECTIVE: Many countries are facing a shortage of cardiac surgeons, who are crucial in meeting the demands of growing number of patients in need of coronary artery bypass grafting. This situation poses a serious challenge, especially in China. The purpose of this study is to determine whether cardiac surgeons are suitable for training in coronary artery anastomosis at an earlier stage in their career. METHODS: We divided 12 cardiac surgeons with no prior experience in coronary artery anastomosis into senior and junior groups for training and assessment. All trainees received training in coronary artery anastomosis for a defined period. We performed in vivo and in vitro examinations before and after training, respectively. Additionally, we assessed individual surgical performance of surgeons by using performance rating scores, including different aspects of surgical skills rated on a five-point scale. RESULTS: The post-training scores (overall, junior, senior) were significantly higher than the pre-training scores (overall, junior, and senior). We observed no differences in pre-training and post-training scores between the junior and senior groups. CONCLUSION: Senior surgeons did not had any significant advantages over junior surgeons with respect to coronary artery anastomosis in the absence of training. Junior surgeons achieved the same results as the senior surgeons after training.

A tissue-based simulation model for cardiopulmonary bypass cannulation/decannulation training.

BACKGROUND: Cardiopulmonary bypass is the basis of open heart surgery. Through simulation-based learning, residents may receive structured training of cardiopulmonary bypass techniques. Therefore, we built a high-fidelity, tissue-based simulation model for cardiopulmonary bypass cannulation/decannulation training. METHODS: The core of the model is a whole block of cadaveric animal heart and lung. The discarded membrane oxygenators are used as blood reservoirs. The tubing and suckers recycled from animal experiments are washed and reused. To set up the model, the cadaveric heart and lung are placed into a container of appropriate size. The "arterial" tubing is connected with a pressure gauge, the distal aorta, the superior vena cava, and arterial cannula, respectively. The "venous" tubing is composed of three independent catheters, respectively, for the practice of venous cannulation, for the connection of sucker and for the practice of placing left atrial/ventricular vent. All tubes are installed on the roller pumps to maintain the correct flow direction. A technician should be responsible for operating the heart-lung machine, clamping and releasing the specific segments of tubing, adjusting the pressure, and cooperating with the trainees to practice. RESULTS: Using the simulation model, 18 residents underwent cardiopulmonary bypass techniques training, with an average satisfaction of 8.94 points. The mean score on the overall fidelity of the simulation model assessed by nine experienced cardiothoracic surgeons was 8.67 points. CONCLUSION: The tissue-based simulation model has a certain degree of realism. Cardiac surgery residents can practice necessary cardiopulmonary bypass cannulation/decannulation techniques by this model.

Invasive Hemodynamic Assessment for the Right Ventricular System and Hypoxia-Induced Pulmonary Arterial Hypertension in Mice.

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. However, the evaluation of right ventricular pressure (RVP) and pulmonary artery pressure (PAP) remains technically challenging in mice. RVP and PAP are more difficult to measure than left ventricular pressure because of the anatomical differences between the left and right heart systems. In this paper, we describe a stable right heart hemodynamic measurement method and its validation using healthy and PAH mice. This method is based on open-chest surgery and mechanical ventilation support. It is a complicated procedure compared to closed chest procedures. While a well-trained surgeon is required for this surgery, the advantage of this procedure is that it can generate both RVP and PAP parameters at the same time, so it is a preferable procedure for the evaluation of PAH models.

An exploration of the surgical skill training curriculum for cardiac surgery residents.

BACKGROUND: A "boot camp" program is commonly adopted in surgical skills training. Due to a shortage of cardiac surgeons, establishment of a well-designed training curriculum for cardiac surgery residents is needed in developing countries. METHODS: We established a comprehensive 3-module training curriculum, including: (1) the cardiopulmonary bypass establishment technique, (2) coronary artery anastomosis and (3) basic surgical skills of thoracoscopy. Each module was designed for one technique, with a training time of 1 week. Each module included theoretical knowledge learning, demonstration by senior surgeons, and practice through simulators and in vivo animal experiment. A series of questionnaires were used to assess the training effect. RESULTS: We organized 50 person-times of training. The overall satisfaction of residents participating in the entire 3-module training was 7.88 points (from a full score of 10 points). The satisfaction of each module was 8.94, 8.13, and 7.63, respectively. The survey suggested the training could increase trainees' confidence in the operation (P < 0.05). Some trainees also proposed some suggestions for the further improvement of the curriculum. CONCLUSIONS: It is feasible to develop a multimodule comprehensive surgical skill training curriculum for cardiac surgery residents in China, whose confidence can be effectively enhanced.

Effects of atrial fibrosis induced by mitral regurgitation on atrial electrophysiology and susceptibility to atrial fibrillation in pigs.

BACKGROUND: The mechanism by which atrial fibrosis leads to the production and maintenance of atrial fibrillation (AF) is unclear. Myocardial biopsies, which have often been used in previous studies, are taken from a single site and do not always reflect the overall condition of atrial fibrosis. AIMS: The aim of this study was to investigate the location of fibrosis in the atria induced by mitral regurgitation (MR) and its effect on atrial electrophysiology and vulnerability to AF. METHODS: Nineteen pigs were divided into three groups. The control group (n=6) underwent a sham operation, and the experimental groups underwent an MR induction operation and were observed for 3 (n=7) or 6 (n=6) months. All the animals were tested for vulnerability to AF. Then, the atria were divided into 12 regions: 6 in the left atrium (LA) and 6 in the right atrium (RA). The conduction velocities (CVs) and effective refractory periods (ERPs) in different regions were examined by electroanatomic mapping, and fibrosis in different regions was examined by Masson staining. RESULTS: With the duration of MR, fibrosis (3.11% ±â€¯0.08% in the control group, 5.85% ±â€¯0.42% in the 3-month group and 8.17% ±â€¯0.23% in the 6-month group, P<.001), vulnerability to AF (0/6 in the control group, 2/7 in the 3-month group and 5/6 in the 6-month group, P<.05) and the effective refractory period (220.1±1.1 ms in the control group, 244.4±1.4 ms in the 3-month group and 289.0±8.9 ms in the 6-month group, P<.001) were increased, while the conduction velocity (1.39±0.16 m/s in the control group, 1.04±0.05 m/s in the 3-month group and 0.89±0.02 m/s in the 6-month group, P<.001) was reduced. These pathophysiological changes were not uniform in different regions of the atria (3.83% ±â€¯0.25% in right atrial fibrosis vs 8.22% ±â€¯0.83% in left atrial fibrosis, P<.001; 5.09% ±â€¯0.34% in the right atrium vs 11.76% ±â€¯0.52% in the left atrium, P<.001). A negative correlation was identified between fibrosis and conduction velocity (P<.001 in the 3-month and 6-month groups), but no correlation was found between fibrosis and the effective refractory period (P=.829 in the 3-month group and P=.093 in the 6-month group). Susceptibility to AF was associated with the dispersion of atrial fibrosis (P=.023). CONCLUSIONS: With the duration of MR, atrial fibrosis increased, and the degree of increase was not uniform among different areas of the atria. The dispersion of atrial fibrosis may contribute to increased susceptibility to AF by influencing the conduction velocity rather than the effective refractory period.

Structural, functional and histological features of a novel ischemic heart failure model.

There is still no satisfactory large-animal model of ischemic heart failure (IHF) with ideal survival rate and model time. The aim of this study is to explore a novel chronic IHF model in swine. 23 healthy Ba-Ma miniature pigs were included. Pigs in the experimental group underwent multiple strategic ligations on side branches of the left anterior descending (LAD) and circumflex coronary arteries. One week later, sequential intervention occlusion of the distal end of the LAD trunk was performed. In the experimental groups, LV end-diastolic (LVEDV) and end-systolic volume (LVESV) gradually increased starting at 4 weeks post operation. At 12 WPO, LVEDV increased from 45.0 ± 2.9 ml at baseline to 110.0 ± 9.8 ml and LVESV increased from 17.0 ± 1.4 ml at baseline to 42.0 ± 3.6 ml. Meanwhile, left ventricular ejection fraction significantly decreased from 73.8 ± 4.2 % at baseline to 31.0 ± 2.5%. According to histomorphometric assessment, viable cells were observed in infarction lesions, indicating the model has replicated the structural and functional features of chronic IHF.

Construction and application of service quality evaluation system in the preclinical research on cardiovascular implant devices.

BACKGROUND: Services for the preclinical development and evaluation of cardiovascular implant devices (CVIDs) is a new industry. However, there is still no indicator system for quality evaluation. Our aim is to construct a service for quality evaluation system for the preclinical research and development of CVIDs based on Fuzzy Analytical Hierarchy Process (FAHP). METHODS: First, we reviewed the related literature to identify and select possible factors. Second, we developed an analytic hierarchy process framework. Third, we developed a questionnaire based on pairwise comparisons and invited 10 experienced specialists to rate these factors. We then used FAHP to compute the weights of these factors and prioritize them. Finally, to demonstrate the effectiveness of the proposed indicator system, a case study was performed as a practical example. RESULTS: Four main indicators (professionalism, functionality, stability and security) and 15 subindicators were selected to form the service evaluation system based on literature review and expert's proposals. According to the weight calculation data, the order of primary indicators by importance, is professionalism (0.6457), security (0.1193), functionality (0.0958) and stability (0.0596) in sequence. Top five secondary indices are personnel's technical ability, facility and equipment attractiveness, data auditability, confidentiality capability and professional service procedures. In the case study, FW's final actual effectiveness value was 0.9076, which is the same as the actual situation. CONCLUSION: The indicator system established in this study is comprehensive, reasonable, reliable and with strong practicality. It is worth popularizing and applying. The implementation of this evaluation system can provide measurable evidence for service demander and a way to improve service quality for suppliers.

The characteristics of a porcine mitral regurgitation model.

The porcine mitral regurgitation (MR) model is a common cardiovascular animal model. Standardized manufacturing processes can improve the uniformity and success rate of the model, and systematic research can evaluate its potential use. In this study, 17 pigs were divided into an experimental group (n=11) and a control group (n=6). We used a homemade retractor to cut the mitral chordae via the left atrial appendage to establish a model of MR; the control group underwent a sham surgery. The model animals were followed for 30 months after the surgery. Enlargement and fibrosis of the left atrium were significant in the experimental group compared with those in the control group, and left atrial systolic function decreased significantly. In addition, model animals showed preserved left ventricular systolic function. There were no differences in left atrial potential or left ventricular myocardial fibrosis between the two groups. Atrial fibrillation susceptibility in the experimental group was higher than that in the control group. Our method enables the simple and effective production of a MR model with severe reflux that can be used for pathophysiological studies of MR, as well as for the development of preclinical surgical instruments and their evaluation. This model could also be used to study atrial fibrillation and myocardial fibrosis but is not suitable for studies of heart failure.

Transapical implantation of a self-expandable aortic valve prosthesis utilizing a novel designed positioning element.

OBJECTIVES: To evaluate a new transapical system which utilizes a novel designed positioning element and a two-step positioning mechanism for easy and accurate implantation of transcatheter valves. BACKGROUND: Transcatheter aortic valve implantation is an important treatment option for non-surgical patients with severe aortic stenosis. However, accurate placement of the transcatheter valve remains challenging. METHODS: Self-expandable aortic valve prosthesis with a flexibly connected, annulus-like positioning element was implanted through a transapical approach in 12 pigs. The positioning element was separated and can be released independent of the valve prosthesis. During valve implantation, firstly, the positioning element was unsheathed and fixed into the aortic sinus. Then, the prosthetic valve was guided to an anatomically oriented position and deployed. Six animals were followed up to 180 days. RESULTS: With the help of the positioning element, all 12 valves were successfully deployed at the anticipated site. The valve release procedure took an average of 7.3 ± 2.5 min. The mean transvalvular pressure gradient was 2.8 ± 1.1 mm Hg at valve deployment. Of the six chronic animals, the mean transvalvular pressure gradient was 3.0 ± 1.0 mm Hg on day 7, and 2.9 ± 1.6 mm Hg on day 180 (P = 0.91). No migration, embolization, or coronary obstruction was observed during surgery and at necropsy. Pathological examination showed anatomically correct positioning of the prosthetic valve without signs of thrombosis or calcification. CONCLUSIONS: In this study, we confirmed the feasibility of the J-Valve transapical system for transapical implantation through a two-step process. Satisfactory hemodynamic and pathological performance during a follow-up of 180 days was demonstrated. © 2016 Wiley Periodicals, Inc.

A Secure and High-Fidelity Live Animal Model for Off-Pump Coronary Bypass Surgery Training.

OBJECTIVE: Existing simulators for off-pump coronary artery (CA) bypass grafting training are unable to provide cardiac surgery residents all necessary skills they need entering the operation room. In this study, we introduced a secure and high-fidelity live animal model to supplement the in vitro simulators for off-pump CA bypass grafting training. DESIGN: The left internal thoracic artery (ITA) of 3 Chinese miniature pigs was grafted to the left anterior descending CA using an end-to-side anastomosis. The free segment of the ITA was fixed on the ventricle surface, making it a simulative CA beating in synchrony with the heart. A total of 6 to 8 training anastomoses were made on each ITA. SETTING: Animal Experiment Center in Fuwai Hospital. PARTICIPANTS: In total, 19 resident surgeons with at least 3 years of cardiac surgery work experience were trained using the new model. Their performances were recorded and reviewed. RESULTS: Simulative coronary arteries were successfully constructed in all 3 animals with no adverse event observed. A total of 19 anastomoses were then completed, 1 pig of 7 anastomoses and the other 2 animals of 6 anastomoses. Time consumption for the anastomosis was 782 ± 107 seconds. Anastomotic leakage was observed in 10/19 procedures. The most frequency site (7/10) was at the toe of the anastomosis. Further, the most common cause was uneven spacing or small margin of the stitches or both. Emergencies occurred during the training process included hypotension (7 procedures), tachyarrhythmia (4 procedures), and low blood oxygen saturation (1 procedure). CONCLUSIONS: This study demonstrated the safety and feasibility of our new live pig model in training resident surgeons. The simulative arteries can be easily accomplished and were long enough to place at least 6 anastomoses. Both on lumen diameter and motion status, they were proven to be a good substitution of the CA.

[Establishment of acute myocardial infarction model in diabetic miniature pigs through video-assisted thoracoscopic surgery].

OBJECTIVE: To explore a new method of establishing acute myocardial infarction model in diabetic miniature pigs through video-assisted thoracoscopic surgery (VATS). METHODS: Seven normal miniature pigs and 7 diabetic miniature pigs underwent VATS by selectively ligating left anterior descending coronary artery and then were evaluated through serology, imaging and histology. RESULTS: The serum levels of troponin (cTni) and myoglobin (MYO) in both groups significantly increased by over 10 folds of upper normal limit after VATS. Echocardiography, MRI and histopathologic analysis showed that the affected myocardial parts were apex, left ventricular wall and interventricular septum cosco section. But heart function of diabetic miniature pigs were relatively lower; infarction area/area-at-risk ratio higher (18.4% ± 5.5% vs 5.3% ± 3.9%, P = 0.03) , myocardial infarction through-wall degree more severe. These were in accordance with poor ischemic tolerance in diabetic myocardia. CONCLUSION: VATS is a safe and effective method for establishing AMI model in diabetic miniature pigs.

[Numerical simulation of LVAD inflow cannulas with different tips].

The tip structure is one of the key factors to determine the performance of left ventricular assist device (LVAD) inflow cannulas. The tip structure influences the thrombosis, hemolysis in cannula and left ventricle and suction leading to obstruction in ventricle. We designed four kinds of inflow cannulas that had different tips and built the numerical models of the four historical used inflow cannulas inserted into the apex of left ventricle. We computed the hemodynamic characteristics of inflow cannulas insertion by Fluent software. We researched the backflow, turbulent flow and pressure distribution of the four inflow cannulas. The results showed that the trumpet tipped inflow cannula had smooth flow velocity distribution without backflow or low velocity flow. The trumpet tipped inflow cannula had the best blood compatibility characteristics. The trumpet structure could prevent obstruction. The caged tipped cannula had serious turbulent flow which could possibly cause thrombosis and the low pressure near left ventricle wall and easily lead to ventricle collapse. The trumpet tipped inflow cannula has the best blood compatibility and is difficult to be obstructed. The trumpet tipped inflow cannula is fit to long-term use LVAD.

Neural progenitor cells derived from adult bone marrow mesenchymal stem cells promote neuronal regeneration.

AIM: It is well known that neural stem/progenitor cells (NS/PC) are an ideal cell type for the treatment of central nervous system (CNS) disease. However, ethical problems have severely hampered fetal NS/PC from being widely used as a source for stem cell therapy. Recently, it has been demonstrated that autologous bone marrow mesenchymal stem cells (BMSC) can transdifferentiate into neural progenitor cells (NPC). The biological function of BMSC derived NPC (MDNPC) in neuronal systems remains unknown. In the present study, we aimed to investigate whether MDNPC can promote in vitro neural regeneration, a process comprising mainly the generation of neurons and neurotransmitters. MAIN METHODS: We co-cultured BMSC, MDNPC or fetal NS/PC with PC12 cells and studied their roles on proliferation, neurite formation and dopamine release from PC12 cells. Furthermore, we also explored the mechanisms by which MDNPC regulate dopamine secretion from PC12 derived neural cells using Western blot. KEY FINDINGS: We found that both MDNPC and NS/PC had similar morphologies and there were no significant differences between MDNPC and NS/PC in promoting PC12 cell proliferation, neurite outgrowth, and dopamine release. We also demonstrated that NS/PC induced dopamine secretion was associated with an upregulation of dopamine transporter (DAT) levels. SIGNIFICANCE: In summary, MDNPC were comparable to NS/PC in promoting neural regeneration, indicating that MDNPC are a promising candidate source of neural stem cells for the treatment of neurological diseases.

Cell viability and dopamine secretion of 6-hydroxydopamine-treated PC12 cells co-cultured with bone marrow-derived mesenchymal stem cells.

In the present study, PC12 cells induced by 6-hydroxydopamine as a model of Parkinson's Disease, were used to investigate the protective effects of bone marrow-derived mesenchymal stem cells bone marrow-derived mesenchymal stem cells against 6-hydroxydopamine-induced neurotoxicity and to verify whether the mechanism of action relates to abnormal α-synuclein accumulation in cells. Results showed that co-culture with bone marrow-derived mesenchymal stem cells enhanced PC12 cell viability and dopamine secretion in a cell dose-dependent manner. MitoLight staining was used to confirm that PC12 cells co-cultured with bone marrow-derived mesenchymal stem cells demonstrate reduced levels of cell apoptosis. Immunocytochemistry and western blot analysis found the quantity of α-synuclein accumulation was significantly reduced in PC12 cell and bone marrow-derived mesenchymal stem cell co-cultures. These results indicate that bone marrow-derived mesenchymal stem cells can attenuate 6-hydroxydopamine-induced cytotoxicity by reducing abnormal α-synuclein accumulation in PC12 cells.

Pretreatment with Tongxinluo protects porcine myocardium from ischaemia/reperfusion injury through a nitric oxide related mechanism.

BACKGROUND: The traditional Chinese medicine Tongxinluo can protect myocardium against ischaemia/reperfusion injury, but the mechanism of its action is not well documented. We examined the involvement of nitric oxide in the protective role of Tongxinluo. METHODS: Miniswine were randomized to four groups of seven: sham, control, Tongxinluo and Tongxinluo coadministration with a nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (L-NNA, 10 mg/kg i.v.). Three hours after administration of Tongxinluo, the animals were anaesthetised and the left anterior descending coronary artery ligated and maintained in situ for 90 minutes followed by 3 hours of reperfusion before death. Area of no reflow and necrosis and risk region were determined pathologically by planimetry. The degree of neutrophil accumulation in myocardium was obtained by measuring myeloperoxidase activity and histological analysis. Myocardial endothelial nitric oxide synthase activity and vascular endothelial cadherin content were measured by colorimetric method and immunoblotting analysis respectively. RESULTS: Tongxinluo significantly increased the local blood flow and limited the infarct and size of no reflow. Tongxinluo also attenuated myeloperoxidase activity and neutrophil accumulation in histological sections and maintained the level of vascular endothelial cadherin and endothelial nitric oxide synthase activity in the reflow region when compared with control group. The protection of Tongxinluo was counteracted by coadministration with L-NNA. CONCLUSIONS: Tongxinluo may limit myocardial ischaemia and protect the heart against reperfusion injury. Tongxinluo regulates synthesis of nitric oxide by altering activity of endothelial nitric oxide synthase.