Physiologic analysis of cardiac cycle in an implantable impeller centrifugal left ventricular assist device

The purpose of this study was to determine the physiologic relationship between the cardiac cycle and the nonpulsatile impeller centrifugal Taita No.1 left ventricular assist device (T-LVAD) in a chronic animal study. The relationship of the cardiac cycle, pump flow, aortic pressure, left ventricle pressure, and pump power were analyzed by 5 phases in 4 stages. The isovolumetric ventricular phase is from mitral valve closure (MVC) to aortic valve opening (AVO) and is called Stage 1. The ejection phase is from AVO to aortic valve closure (AVC) and is called Stage 2. The isovolumetric relaxation phase is from AVC to MVC and is called Stage 3. The passive filling and atrial contraction phase is from MVC to mitral valve opening (MVO) and called Stage 4. Based on evidence from the physiologic volume change of the left ventricle, the change of pump flow of the T-LVAD in a cardiac cycle by variable voltages of pump control was evaluated using animal models. After left posteriolateral thoracotomy via the fifth intercostal space under general anesthesia, the nonpulsatile centrifugal T-LVAD was implanted into 2 healthy calves. The inflow of the T-LVAD was inserted into the left ventricle through the mitral valve via the left atrial appendage. The arterial blood pressure waveform was measured and recorded on the outflow of the T-LVAD. The 4 phases of a cardiac cycle were defined as MVC-AVO (Stage 1), AVO-AVC (Stage 2), AVC-MVO (Stage 3) and MVC-MVO (Stage 4) according to the outflow pressure of the outflow of the T-LVAD and differential pressure between the outflow and inflow of the T-LVAD. We carried out the real-time waveform measurement for electrocardiogram, the outflow pressure, the T-LVAD flow and the speed, as well as open loop and constant voltage (V). In a cardiac cycle, the sensing current of the T-LVAD was inverse to the speed. The flow of the T-LVAD at the 4 stages was measured individually and analyzed with different control voltages from 10 to 18 V. The highest flow ratio of MVC-AVC/AVC-MVC was noted when the T-LVAD worked on 14 V. By using analysis methodology of the flow ratio of a cardiac cycle, the optimal physiologically effective control of the T-LVAD might be achieved.     

Myocardial revascularization in patients with end-stage renal disease: Comparison of percutaneous transluminal coronary angioplasty and coronary artery bypass grafting

Background: Ischemic heart disease is the major cause of death inpatients with end-stage renal disease. The high prevalence of coronary artery disease results in a rising number of dialysis patients requiring myocardial revascularisation. Objective: The objective of this study was to compare the outcomes of recurrent angina, myocardial infarction, rate of reinterventions and cardiovascular death following percutaneous coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) inpatients with end-stage renal disease. Patients and methods: In a retrospective investigation 40 patients with chronic renal failure undergoing primarily PTCA and 65 patients undergoing CABG were included. Both groups were comparable for gender, duration on dialysis and the number of cardiovascular risk factors per patient. Patients undergoing PTCA were younger (53 ± 12 years vs. 57 ± 8 years; p < 0.05) and more often diabetics (30% vs. 14%; p < 0.05). Results: Most patients in both groups had a multi-vessel disease (95% in the CABG group vs. 74% in the PTCA group), in the CABG group there were significantly more patients with a triple-vessel disease (62% with vs. 40%in the PTCA group; p < 0.01), PTCA was primarily successful in 95% of the patients while complete revascularization was achieved in 88% of patients undergoing CABG. The perioperative mortality after CABG was 4.8% as compared to none after interventional revascularisation. The cumulative freedom of angina after 6, 12 and 24 months after intervention was significantly lower after PTCA (54%, 40%, 29%) than after bypass grafting (97%, 94%, 90%, p < 0.001). The frequency of reinterventions following PTCA was significantly higher compared to patients following CABG (p < 0.001). After PTCA 15 patients needed further revascularisations, 8 of them underwent CABG, whereas after CABG only two patients required additional myocardial revascularisation. There was no significant difference in the overall mortality between both groups; the survival rate after 12 and 24 months was 95% and 82% after PTCA and 93% and 86% after CABG, respectively. Condition: Although patients receiving CABG had a more severe coronary artery disease the overall mortality was comparable and clinical and functional outcome was improved compared to patients after coronary angioplasty. This revised version was published online in June 2006 with corrections to the Cover Date.     

Comparison of laparoscopic versus open cholecystectomy in patients with cardiac valve replacement

To evaluate the benefits and safety of laparoscopic cholecystectomy (LC) in patients with cardiac valve replacement (which frequently leads to cholelithiasis), 12 patients with cholelithiasis associated with cardiac valve replacement were studied. The patients were divided into two groups, of 6 patients each, according to the type of operation performed, open cholecystectomy (OC) or LC. The postoperative course was monitored with respect to laboratory data on postoperative days (POD) 1, 3, and 7. The mean duration of operation, blood loss, days to food resumption, length of hospital stay, and morbidity were compared between the two groups. Significant differences (P < 0.05) were found between the OC and LC groups in white blood cell counts on POD 1 (12 980 ± 3040/mm³ vs 8300 ± 1590/mm³), days to food resumption (2.7 ± 0.4 days vs 1.0 ± 0.7 days), and length of postoperative stay (15.8 ± 1.0 days vs 10.8 ± 1.6 days). There were no complications in the LC group, but 1 patient in the OC group had heart failure postoperatively. Our findings indicate the efficacy and safety of LC in patients with cardiac valve replacement. Received: August 14, 2000 / Accepted: December 22, 2000     

Pre-operative oral carbohydrate treatment before coronary artery bypass surgery

Background: Cardiac surgery is a stress that causes insulin resistance, which leads to an increase in insulin requirement. The aim of the present study was to evaluate the effect of a pre-operative oral carbohydrate drink vs. overnight fasting on perioperative insulin requirements in non-diabetic patients undergoing elective coronary artery bypass grafting (CABG) surgery.
Methods: One hundred and one patients scheduled for CABG were enrolled in the study. After fasting overnight, the patients were randomised into two groups. In the control group (C), no drink was given in the morning. In the treatment group (T), the patients ingested 400 ml of carbohydrate fluid 2 h before induction of anaesthesia. Blood glucose and insulin requirement was recorded. Gastric drainage was measured. Post-operative nausea and vomiting was recorded.
Results: Neither the number of patients requiring insulin nor the amount of insulin required to maintain normoglycaemia differed between the study groups. More patients in the treatment group experienced nausea post-operatively (26 vs. 16, P =0.044), but vomiting was equally common in the study groups (10 vs. 7). Intra-operative gastric drainage was 26.8±57.9 ml in the treatment group vs. 16±37.9 ml in the control group (NS).
Conclusion: In this study patient population, a pre-operative oral carbohydrate drink did not reduce post-operative insulin resistance or post-operative nausea and vomiting. According to our findings, it is safe to allow cardiac surgery patients to drink clear fluids up to 2 h before induction of anaesthesia, because gastric emptying of the drink was almost total and no aspiration occurred.     

贲门癌患者围术期肠内营养的临床研究

目的研究贲门癌患者围术期肠内营养的实施方法、效果。方法对209例贲门癌患者依据术后给予不同的营养支持方法随机分为两组,肠内营养组146例,术后施行早期肠内营养;静脉营养组63例,贲门癌术后给予全静脉营养支持;比较两组患者术后并发症发生情况,术后恢复情况,检测手术后理化指标。结果两组患者术后均未发生吻合口瘘。术后并发症发生率肠内营养组明显低于静脉营养组(P<0.01),而肠内营养组腹泻发生率高于静脉营养组(P<0.01),两组腹胀发生率差异无统计学意义(P>0.01)。术后肠鸣音恢复时间,肛门排气、排便时间和住院时间,肠内营养组较静脉营养组短(P<0.01)。术后白蛋白、球蛋白、总蛋白量肠内营养组高于静脉营养组(P<0.01),而血尿素氮、肌酐和中性粒细胞低于静脉营养组(P<0.01)。结论贲门癌患者围术期肠内营养是安全、有效、可行的,较静脉营养组有明显的优势。     

高氧液预处理对心脏瓣膜置换术患者心肌肌钙蛋白Ⅰ和心肌酶学的影响

目的观察高氧液预处理对心脏瓣膜置换手术患者缺血-再灌注心肌的保护作用。方法将30例择期心脏瓣膜置换术患者随机分成观察组和对照组。对照组患者在麻醉后切皮前（T0）至心肺转流（CPB）开始后10min,静滴复方氯化钠注射液10ml／kg;观察组给予相等容量的高氧液。分别于T0、CPB开始后1h（T1）、主动脉开放后2h（T2）、24h（T3）测定乳酸脱氢酶（LDH）、肌酸激酶（CK）、肌酸激酶同功酶（CK—MB）、α-羟丁酸脱氢酶（HBDH）和心肌肌钙蛋白I（cTnI）。结果与T0时比较,两组T1、T2、T3时心肌酶和cTnI测定值均增高（P〈0．05）。两组间比较,LDH、CK—MB在T2、T3时,CK和cTnI在T1、T2、T3时,HBDH在T1时,观察组明显低于对照组（P〈0．05）。术后24h多巴胺用量,观察组明显低于对照组（P〈0．01）。结论高氧液预处理能减轻心肌缺血-再灌注损伤后酶学改变。     

Initial fixation strength of a new hybrid technique for femoral ACL graft fixation: the bone wedge technique

Background Aperture fixation with interference screws matching the diameter of the tunnel is associated with the risk of graft laceration and graft rotation. Hypothesis A hybrid fixation technique (extracortical and aperture fixation) with undersized interference screw placed behind a bone wedge provides a higher fixation strength as aperture fixation with a screw alone matching the size of the tunnel. Study design Experimental laboratory study. Methods We evaluated the initial fixation strength (single cycle and cyclic loading tests) of hybrid and interference screw aperture fixation using different sized interference screws in porcine knees. Results Analysis of yield load, maximum load and stiffness in the single cycle loading test showed no statistically significant differences for hybrid fixation with a 1 mm undersized screw and aperture fixation with a screw matching the size of the tunnel. The use of an undersized screw alone resulted in low fixation strength. Conclusion The initial fixation strength of the hybrid technique with undersized screws is comparable to that of interference screw fixation matching the size. Clinical relevance The new “bone wedge fixation” is an alternative for ACL graft fixation without the risk of graft laceration and graft rotation.     

肾功能损伤分级系统在成人心脏术后的应用

Objective The aim of this study was to evaluate of adilty of two acute renal failure-specific scoring systenms (the classification by Bellome et al and the AKIN criteria) for predicting hospital mortality after cardiac surgery in adult patients. Methods Between October 1 st 2006 to Decemjber 31 st 2006, 509 adult patients who ungerwent coronary artery bypass grafting (CABG) and/ or valve operation were enrolled in this study. The medical data collection included gender, age, types of operation, perioperative he- modynamic parameters, urine output, biochemical parameters and outcome. Renal function was assessed daily according to the classi- ficatinn by Bellomo and the AKIN criteria, respectively. As references, Acure Physiology and Chronic Health Evaluation(APACHE) Ⅱ and Sepsis-related Organ Failure Assessment (SOFA) score were also calculated. Resuits Three hundred and forty-one patients were male (67.0%), and 168 were female (33.0%), mean age was (56.2±12.0) years old. Tnree hundred and nine patieats un- derwent CABG, 182 underwent valve operation and 18 underwent CABG plus valve operation, Mean duration of ventilation support was (20.4±17.7) houra, and the ICU stay was (1.4±1.0) days. Postoperative hospital stay was (13.8±9.1) days. According to the classification by Bellomo., the highest in-hospital mortality was 52.9% in ARFS group. Mahiplicatinn of in-hospital morality rate was abserved (X2 for trend, P<0.01) in 0.4% (non-ARF), 1.2% (stage 1), 12.0% (stal～ 2) and 32.4% (stage 3) of pa- tients based on the AKIN criteria. By applying the area under the receiver operating characteristic ourve, the classification by Bellomo and the AKIN criteria had good discriminative power. Furthering, multivariate logistic regression analysis verified that the Odds Ratio of the AKIN criteria was 5.478 (P =0.028, 95% Confidence Interval 1.027- 24.856), after adjusting for gender and age. Con- clusion Analytical data confinned good discriminative power of both the AKIN criteria and the classification by Bellomo for predicting hospital mortality of adult postoperative patient with ARF.     

完全性房室间隔缺损的外科治疗

目的回顾性总结手术治疗完全性房室间隔缺损的经验。方法112例病儿,≤6个月43例(38%,X组),>6个月69例(62%,Y组)。85例行心导管检查。Rastelli A型89例,Rastelli B型10例,Ras- telli C型13例。手术技术分单片法,双片法和简化单片法。术中经食管超声检查发现异常而即刻再次手术者7例(二尖瓣反流4例,二尖瓣狭窄2例,左室流出道梗阻1例)。术后入重症监护室,左房压8～21 mm Hg,中心静脉压7～12mm Hg。呼吸机平均应用47h,监护室平均滞留6.3d。结果室间隔缺损残余分流(直径>2mm)13例,二尖瓣中度反流12例,完全性房室传导阻滞4例。院内死亡6例(X组1例,Y组5例)。术后随访91例(81%),随访1～5年,平均2.3年。1例术后1年因肺炎心衰死亡,1例术后2年因二尖瓣中-重度反流而换瓣。结论院内死亡率提示,小于6月龄完全性房室间隔缺损病婴手术是安全的。随着年龄增大,瓣膜成形效果、肺动脉高压的预后可能会更差。双片法修补室间隔缺损较易发生残余漏(9例,18%),简化单片法出院时二尖瓣关闭不全发生率明显高于另外两种方法(6例,16%)。     

益生菌联合乳果糖对重症心脏瓣膜病术后腹腔内压的影响

目的：探讨益生菌联合乳果糖对重症心脏瓣膜病患者术后腹腔内压（IAP）及胃肠功能、预后的影响。方法2013年8月至2014年8月入选的56例患者并被随机分为两组,各28例。治疗组术后第1天开始使用益生菌联合乳果糖,持续至术后第7天;对照组未使用益生菌及乳果糖,其他治疗同治疗组。通过膀胱测压法测量两组患者术前和术后第1~5天的IAP,记录两组患者术后首次排便时间、ICU停留时间、术后住院时间;记录两组患者术后腹腔高压（IAH）、腹腔间隔综合征（ACS）、胃肠功能障碍及死亡例数。结果治疗组与对照组术前IAP差异无统计学意义[（3.96±1.63）mmHg vs（3.63±1.58） mmHg,t=0.44,P=0.63],两组术后IAP均呈先上升后下降趋势,治疗组和对照组分别在术后第3、4天达最高点,术后第1天两组HAP水平差异无统计学意义[（11.87±2.22）mmHg vs （11.58±2.76）mmHg,t=1.62,P=0.11],术后第2天开始差异有统计学意义（术后第2~5天的t值分别为2.24、2.47、4.23、4.92,P值分别为0.04、0.02、0.00、0.00）;两组术后首次排便时间（t=2.36,P=0.03）、ICU停留时间（t=3.87,P=0.00）及术后住院时间（t=2.76, P=0.01）之间差异均有统计学意义;治疗组与对照组术后IAH发生率（14.28%vs 39.28%,χ2=4.46, P=0.04）、胃肠功能障碍发生率（7.14%vs 28.57%,χ2=4.38,P=0.04）方面差异均有统计学意义。结论重症瓣膜病术后早期联合使用益生菌和乳果糖可有效降低IAP,改善胃肠功能,降低ICU停留时间和术后住院时间。