The deepening of our understanding on the cardiac electrophysiology mechanism and the progress on cell transplantation technique have expanded our view in treating various kinds of cardiac diseases. Over the past few years literatures have reported many kinds of cell transplantation techniques for treating various types of bradyarrhythmias, such as complete heart block and sinoatrial node dysfunction, and impressive achievements have been made by far. This review discusses the advantages and flaws of the existing strategies and the future of biological pacemakers.

BACKGROUND: Hyperpolarization-activated cyclic nucleotide-gated (HCN) current plays an important role in regulating heart spontaneous pulsation.OBJECTIVE: To observe target gene expression and electrophysiological characteristics of pig bone marrow mesenchymal stem cells (BMSCs) transfected with hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) gene recombinant adenovirus.DESIGN, TIME AND SETTING: Cell-gene in vitro study was performed at the Laboratory of Thoracic and Cardiovascular Surgery,Second Military Medical University of Chinese PLA from July 2007 to March 2008.MATERIALS: Yorkshire pig was supplied by Animal Institute, Second Military Medical University of Chinese PLA. HCN2 plasmid was presented by Professor Dario DiFrancesco from Italy. Recombinant adenovirus Ad.HCN2 was constructed and stored using Ad5 in this laboratory.METHODS: Pig BMSCs were isolated with combination of gradient centrifugation of Percoll and adherent treatment in vitro.Ad.HCN2 was transfected at multiplicity of infection=50. We also set non-transfection and transfected Ad.Null groups.MAIN OUTCOME MEASURES: Expression of HCN2 mRNA was detected with RT-PCR, and expression of HCN2 channel protein was examined with immunofluorescent staining. Electrophysiology of HCN2 channel protein was measured with whole-cell patch clamp.RESULTS: No amplified fragments were found in the non-transfection and transfected Ad.Null groups, but amplified fragments were determined at 250-500 bp following Ad.HCN2 amplification, which was the same as plasmid carrying HCN2 gene. Staining strength of cell nuclei following transfection was significantly weaken compared with cell membrane and plasma, which showed identical distribution as HCN2 protein. No HCN2 protein was detected in the non-transfection and transfected Ad.Null groups.Pacemaker current could be recorded with a whole-cell patch clamp. It was fully activated around -140 mV with an activation threshold of -60 mV, presenting voltage dependence. CsCI (4 mmol/L) reversibly blocked the inward currents. No pacemaker current was detected in the non-transfection and transfected Ad.Null groups.CONCLUSION: The HCN2 recombinant adenovirus carrier was transferred into serial subcultivation porcine bone marrow mesenchymal stem cells. HCN2 channel protein has been expressing. Pacemaker current could be recorded with a whole-cell patch clamp.

Objective:To investigate the survival of rabbits receiving autologous left auricle cardiomyocytes transplantation into the infarcted myocardium and to assess the effect of transplantation on the peripheral blood supply, heart rate, and cardiac function. Methods: Healthy adult rabbits were randomly divided into transplantation group (n=8) and control group (n=8). The myocardial infarction (MI) models were established by ligating the left anterior descending arteries in all rabbits. Four weeks later the left auricles were harvested and the auricle cardiomyocytes were isolated and labelled with DAPI ex vivo. Rabbits in the transplantation group were injected with DAPI-labelled cell suspension into the infarcted areas and those in control group received culture medium. All the rabbits were examined by electrocardiogram (ECG) and 2-D ultrasonic cardiogram (UCG) 4 weeks after transplantation. Specimens were harvested from the transplanted areas and observed histologically. Results: All rabbits survived 4 weeks after transplantation. ECG showed that the heart rate in transplantation group was faster than that in control group (P

Objective To explore and conclude the influence factors of long-term outcomes of mitral valve repair for moderate and severe mitral regurgitation due to myxomatous degeneration.Methods To review the in-patient data and followup outcomes of 261 patients after mitral valve repair for moderate and severe mitral regurgitation due to myxomatous degeneration from Jan 1993 to Jan 2008 in Changhai Hospital of Second Military Medical University.Results There were 7 perioperative deaths and 254 survivors who obtained satisfactory perioperative outcomes.During the follow-up,24 patients were lost and 230 patients were followed up from 36 months to 174 months (77.3 ±30.3) months and follow-up rate was 90.6％.Multivariate Cox regression shows age ≥ 60 years old,left ventricular ejection fraction ＜ 0.50,undergoing combined coronary artery bypass grafting were the independent risk factors for long-term death after operations and left ventricular ejection fraction ＜ 0.50,New York Heart Association functional classification Ⅲ-Ⅳ,anterior leaflet prolapse were the independent risk factors for long-term recurrent moderate or severe mitral regurgitation after operations and prosthetic ring or band annulopasty was a protective factor.Conclusion The age ≥60 years old,left ventricular ejection fraction ＜ 0.50,undergoing combined coronary artery bypass grafting,New York Heart Association functional classification Ⅲ - Ⅳ,anterior leaflet prolapse,and prosthetic ring or band annulopasty were closely related with long-term adverse events after operations.

Objective To develop a novel method for treating complete heart block by autotransplantation of simus node node cells to right ventricular anterior wall.Methods Twenty healthy mongrel dogs were involved in the present study.The dogs were randomly assigned to transplant group or control group(n=10).The sinus node (SN)was harvested and isolated in vitro after an electronic pacemaker was implanted and complete heart bolck was introduced.The SN cells from dogs of transplant group were injected to autogenic right ventricular wall.Commensurable culture medium was implanted to ghe same position of dogs in control group.Two weeks later,detailed electropohysiological study was performed.For investigating the variation of the rhythm,epinephrine was administrated through femoral vein to dogs of transplant group.Results Most of isolated SN cells from dogs were thin-spindle shape,and cell activity was fine.The SNs by VG stained displayed typical structural feature.2 weeks after cell autotransplantation,higher heart rates were achieved from transplant group than that in control group(P＜0.05).This rhythm was stable in 4 weeks and became faster remarkably after administration of eninephrine(P＜0.05).Conclusion SN cell of dogs tutorgrfted into right ventricular anterior wall can form new pacemaker site in ventrcle and improve ventricular rate of complete heart bolck.This pacemaker site can also be regulated by epinephrine.

Objective To summary the methods and results of first and second operations on patients with aortic valve disease and non-specific aortitis.Methods The total 34 patients including 23 cases with aortitis and 11 cases with Behcet disease were studied from Jan 2000 to Dec 2010.The first operation was Bentall procedure in 18 cases and AVR in 16 cases.Fourteen of 16 cases who had AVR developed severe paravalvular leakage,and undewent the second operation including 10 aortic root replacement (8 valve-conduit and 2 homograft) and 4 non-anatomic AVR.Results Eighteen patients who had first operation of Bentall procedure all survive without aortic pseudoaneurysm after the follow-up of 6 months to 11 years.Fourteen redo cases all survive except for one case died of repture of aortic pseudoaneurysm 1.2 years postoperatively.Conclusion Preoperative diagnosis in these patients is very difficulty.The first operation of root replacement is of choice.The second operation is very difficulty to handle,root replacement can achieve satisfactory results.Non-anatomic AVR is easy to perform,and good hemo stasis intraoperatively,and is a satisfied alternative method with good results.

BACKGROUND:Our preliminary study found that the monocusp valves made of ultramicropore expanded
polytetrafluoroethylene (ePTFE) revealed no significant thrombus, calcification, or degradation 20 weeks after implanted into the descending aorta and the left pulmonary artery in sheep, which verified the good property of ePTFE. However, the surface of ePTFE in the left pulmonary artery was covered with obvious neointima.
OBJECTIVE: To assess the biocompatibility of phosphorylcholine-coated ePTFE.
METHODS:ePTFE surface was modified by phosphorylcholine derivative. Then the changes of surface shape, tensile stress at yield and elasticity modulus, water contact angle, and protein absorption capacity of ePTFE after surface modification were observed. (1) Hemolytic test: the leaching solution of phosphorylcholine-coated ePTFE, leaching solution of uncoated ePTFE, normal saline, and distiled water were added to the diluted human blood, respectively. (2) Platelet count test: the phosphorylcholine-coated ePTFE, uncoated ePTFE, high density
polyethylene, and Zymosan A were added to the whole blood samples from healthy volunteers, respectively.
(3) Platelet activation test: the phosphorylcholine-coated ePTFE, uncoated ePTFE, γ-Globulins, and Zymosan A
were added to the whole blood samples from healthy volunteers, respectively.
RESULTS AND CONCLUSION: The mean micropore diameter of ePTFE was significantly decreased after
phosphorylcholine coating (P < 0.001). The hydrophilicity and the ability of suppressing protein adsorption were
significantly strengthened after phosphorylcholine coating (P < 0.001). Phosphorylcholine coating did not influence
ePTFE in biomechanical properties and hemolytic test. The platelet count test and platelet activation test demonstrated that phosphorylcholine coating significantly improved anti-thrombus function of ePTFE. So, phosphorylcholine coating can enhance anti-thrombus function, suppress protein adsorption, and improve biocompatibility of ePTFE.

Objective To investigate the effects of levodopa benserazide hydrochloride combine with dl-3-butyl phthalide capsule on patient's limbs function after stroke. Methods Ninety patients with stroke were randomly divided into rehabilitation group,treatment group and control group,and 30 cases for each group. Patients in rehabilitation group were treated with exercise therapy,in treatment group were given exercise therapy and levodopa Benserazide and Dl-3-butylphthalide capsules,and in control group were given placebo treatment. Adult hemiplegic motor function score(FMA)and motor function assessment scale(MAS)were used to assess the motor function and lower extremity function before treatment and 8 weeks after treatment. Results Before treatment,FMA and MAS in rehabilitation group,treatment group and control group were(22. 6 ± 3. 6), (23. 1 ± 2. 5)and(20. 3 ± 2. 9),and(1. 6 ± 0. 6),(2. 1 ± 0. 5),(1. 7 ± 0. 9),respectively. There was no significant differences between the two groups( F = 1. 64,P > 0. 05;F = 1. 66,P > 0. 05). After 8 weeks of treatment,FMA and MAS in rehabilitation group and treatment group were(60. 6 ± 3. 5),(14. 6 ± 1. 1),and (75. 7 ± 4. 5),(17. 7 ± 4. 5),significant improved more than that before treatment(t = 1. 738,1,716,1. 732 respectively;P < 0. 05). Meanwhile,patients in the treatment group improved more than that in rehabilitation group(P < 0. 05),and they were superior to patients in control group((31. 0 ± 3. 6),(5. 5 ± 1. 1);P < 0. 05). Conclusion Benserazide combined with dl-3- butyl phthalide capsule can further improve the limbs function.

The relation between left atrial (LA) size and myocardial pathological changes, and clinical implications were studied in 25 patients with- rheumatic mitral stenosis. The results showed that LA size was significantly correlated with pathological severity of myocardium (P 100 ml/m2 and accompanied by moderate or severe pathological changes easily suffered from Af (P200ml/m2 and severe pathological changes. The results suggest that occurence of Af may be predicated based on the LA volume and Af cardioversion should be selectively performed to obtain better results.

Objective:To fundamentally solve the problems of valve dysfunction caused by limited size of artificial valve, high requirements for implantation technology, destruction of subvalvular structure and proliferation of fibrous endothelial tissue. We have developed a prosthetic valve with zero left ventricular occupancy. The valve frame is appropriately higher than the existing products, slightly chimney shaped, fully accommodates the movement of the valve leaves in the valve frame, and completely supraannular surgical implantation. This study uses this valve for preclinical animal test.Methods:Seven sheep underwent the replacement of the artificial valve under the direct vision of cardiopulmonary bypass. Warfarin was used for anticoagulation for 6 months 24 hours after operation. The blood biochemistry, anticoagulation and cardiac color Doppler ultrasound were detected after operation. The sheep were killed 180 days later for autopsy to observe whether the artificial valve caused thromboembolism. The efficacy and safety of valve were observed.Results:Two of the seven sheep died within 24 hours after operation, and five survived for a long time. Later, they were killed at 180 days. The mechanical properties of the artificial valve were good, and there was no thromboembolism around the artificial valve and important organs. The tissue layer of suture ring has been completely organized and endothelial cells, and the thickness of tissue layer is about 0.6-1.0 mm. The mitral valve of experimental animals can be opened and closed freely, with smooth surface and no abnormal echo. The follow-up of color Doppler ultrasound showed that the left ventricular ejection fraction was normal (0.60-0.70) before and 6 months after operation. The results of cross valve pressure difference and blood flow velocity of artificial valve were good (vmean was far lower than 5 mmHg(1 mmHg=0.133 kPa) and pmean was lower than 1 m/s) , suggesting that the hemodynamic performance of artificial valve was good. Left ventricular retrograde angiography showed that the artificial valve was completely located in the left atrium with good position and normal opening and closing. There was no obvious perivalvular leakage and other abnormalities. Within 7 days of blood test, the indexes of surgical stress were more abnormal than those before operation. At 12 and 24 weeks, there were no obvious abnormalities in blood routine test, liver and kidney function and other blood test indexes of animals in each group.Conclusion:The new chimney shaped mechanical valve implanted completely above the mitral annulus has good wear resistance, histocompatibility, antithrombotic and hemodynamic performance.