Cystic brain stem necrosis in a premature infant after prolonged bradycardia

Summary A case is described of symmetrical cavitating brain stem necrosis produced by cardiac arrest in a premature infant. Two months after birth this 25-week gestational age infant suffered a prolonged episode of bradycardia. She was resuscitated and then died 3 weeks later. The autopsy revealed striking bilateral cavitation of the brain stem tegmentum extending in a columnar fashion from the upper portion of the spinal cord to the hypothalamus. The findings in this case are identical to the brain stem injury experimentally produced by complete cardiac arrest in the rhesus monkey.     

Effects of complete heart block on myocardial function, morphology, and energy metabolism in the rat.

AIMS: Severe sustained bradycardia may cause acute and possibly chronic congestive heart failure (CHF). The aim of this study was to investigate acute and chronic effects of complete heart block (CHB) on cardiac function, morphology, and creatine (Cr) metabolism. METHODS AND RESULTS: CHB was induced in male Sprague-Dawley rats (approximately 250 g, n = 11) by means of electrocautery applied to the region of AV node and were compared with controls (n = 15). The rats were investigated at 1, 3, and 12 weeks after CHB induction with transthoracic echocardiography. Invasive haemodynamic assessment of left and right ventricular pressures was performed at 12 weeks. After the sacrifice, the hearts were freeze-clamped for analysis of myocardial Cr, and high energy phosphometabolites. The efficacy of operative procedure was 54%. The peri-operative mortality rate was 20%. Heart rate (HR) decreased by approximately 50% (P < 0.01) while stroke volume (SV) increased 2.5 times (P < 0.01) in the CHB rats. Cardiac index remained unchanged. The rats with CHB grew normally and were in no apparent distress. Filling pressures in left and right ventricles were normal. The CHB rats developed marked cardiomegaly with biventricular dilatation and eccentric left ventricular hypertrophy (P < 0.01). There was no change in the myocardial content of Cr and high energy phosphometabolites. CONCLUSION: Rats with CHB are compensating for reduction in HR with increased SV without haemodynamic and biochemical characteristics of CHF. This model may be useful to study the effects of CHB and bradycardia on myocardial structure, function, electrophysiology, and metabolism as well as for studies of cell therapy for reparation of AV conductance.     

质疑Frank—Starling心脏定律

心脏收缩释放的能量（作功）是心肌纤维长度（心室舒张末期容积，EDV）的函数，即Frank—Star一1ing（FS）心脏作功定律，被誉为心脏生理学中的“经典”理论。对此，笔者从各种不同角度进行了探讨：首先分析了Frank伸展离体心肌和Starling及其同事使用心肺制备做的实验与动物生理实际的差异，以及人们在实验中观测到的增加心肌前负荷引起收缩力增强的现象（FS现象），认为：①在正常生理条件下的动物体内，来自心脏以外的、如同心肺制备中那样人工控制心室充盈压力升高、引起EDV增加的那种血液的重力动力是不存在的。②另一方面，人为地增加前负荷，那是改变了心肌收缩时的外环境条件。③由此而激发出的FS现象，是心脏适应其外环境条件变化所作出的反应。④此种心肌收缩力增强的反应，需通过心肌细胞内部与收缩过程发生有关的心肌兴奋一收缩和化学一力学偶联等一系列生化机制（不恒定因素）方能得以实现。⑤根据他们实验中观测到的FS现象，在逻辑上不能得出前负荷这一心肌收缩时的外环境条件变化调控其作功的推论。换言之，所有的在实验中被激发出来的FS现象，都不足以成为支持FS心脏定律的证据。然后，引用国内外公认的计算心脏每搏射血作功（w）的生物物理学公式“w=P×（EDV—ESV）”，证明了w和EDV之间没有函数关系。根据心脏作功的医用物理学和生物数学的基本原理，笔者认为Frank—Starling心脏定律表达的不是心脏作功的规律。     

国产重组人脑钠素与硝普钠用于心脏手术围术期处理的对比研究

目的 对重组人脑钠素（rhBNP）用于心脏手术围术期处理的可行性、安全性和有效性进行初步观察，并与硝普钠的作用进行比较。方法 选择择期心脏手术病人22例，随机分为rhBNP组（B组）和硝普钠（SNP）组（s组），每组11例。比较rhBNP与SNP对病人血流动力学和肝肾功能的影响。结果 与给药前和S组比较，B组用药后15、30、60、120和180min各点心输出量增加显著（P〈0．05，P〈0．01）；B组与给药前比较，给药后即刻、15、30和60min时点外周血管阻力下降显著（P〈0．05）；给药后即刻、15和30点与S组比较，下降显著（P〈0．05）。B组肺毛细血管楔压（PCWP）与用药前比较，用药后即刻、15、30、60、120和180min下降显著（P〈0．05，P〈0．01）；与S组比较，给药后30、60、120和180min差异有统计学意义（P〈0．05，P〈0．01）。S组PCWP与用药前比较，用药后60min、120min和180min下降显著（P〈0．05）。B组与输注rhBNP前以及S组比较，平均动脉压、心率和中心静脉压差异均无统计学意义。输注rhBNP后病人24h尿量明显增加。用药过程中以及30d后进行电话随访，未见药物不良反应。结论 rhBNP用于心脏手术围术期处理是可行的，具有改善心功能和稳定循环的作用。     

Cardiac hemangioma presenting as atypical chest pain.

A 44-year-old man presented with atypical chest pain and dyspnea. Investigation revealed the presence of a 15-mm rounded, well-vascularized left-ventricular mass. The mass was removed surgically and histopathologic evaluation identified a cardiac hemangioma.     

彩超对人工心脏起搏的血液动力学研究

目的　本文采用彩色多普勒超声心动图研究了心脏起搏前、后的血液动力学变化 ,以评价不同起搏模式血液动力学效应。方法　对 32例植入人工心脏起搏器的患者 ,采用 M型、二维及多普勒超声心动图检测了心室按需起搏 (VVI)不伴室房逆传 (A组 )和伴室房逆传 (B组 )及房室顺序起搏 (AVP) (C组 )的左心结构、左室的泵血功能、左室收缩及舒张功能指标。结果　 1 .心室起搏 (VP)不伴室房逆传和房室顺序起搏(AVP)组起搏后的心输出量 (CO)明显增加 (P<0 .0 5〉,而 VP伴室房逆传组则 CO增加不明显 (P>0 .0 5 )。心搏量 (SV)各组均呈下降趋势 ,VP伴室房逆传者下降更明显。但起搏后三组间比较无显著差异 (P>0 .0 5 ) ;2 .VP后左室的收缩及舒张功能均有受损 ,而 AVP后主要损害左室的舒张功能 ,对左室收缩功能影响不明显 ;3.VP伴室房逆传者 ,起搏后血液动力学效应在三组间最差。结论　无论 VP还是 AVP起搏后由于心率的增加均可使CO增加 ,但对左室的功能均有不同程度的损害 ,VP伴室房逆传者最为明显 ,AVP损害程度三组间最轻。因此 ,AVP也并非真正的生理起搏器。临床上提倡埋植更接进生理状态的起搏器 (多部位心脏起搏 ) ,以保持良好的心功能状态     

Ross术后中远期主动脉瓣反流的危险因素分析

Objective To analyze the risk factors of the postoperative mid- and long-term aortic valvular regurgitation after ROSS procedure(pulmanary valve homograft transplantation). Methods Between March 1998 and July 2007,47 patients[25male, 22 female, mean age (13.31±5.79) years, ronge 1-34 years] with aortic valvular disease underwent the Ross procedure at our insti tution. There were 6 patients suffering fron rheumatic heart disease and 41 patients suffering from congenital heart disease. The aver age aortic blood flow velocity was (4.67±3.47) m/s, the average pressure gradient across aortic valve (88.26±58.06)mm Hg, LVEDD (45.53 ±10.78) mm, EF 0.69±0.08. All the patients were followed up in out-patient departement by ultrasonic cardio gram. Multiple logistic regression analysis was performed to find out the risk factors of the postive aortic valvular regurgitation. Results There was no poetoperative death in hospital. The mean follow-up periods was (36.15±22.1) months, rasnge from 12 to 110 months and none long-dated death. Compared with the data recorded in hospital, the diamenters of the aortic sinus and aortic annu lus enlarged significantly, respectively from (26.16±5.10) mm to (32.37±6.84) tam and from (19.41 ～3.98) mm to (23.45± 5.86) mm. The average flow velocity d the homograft (new aortic valve) was(1.39±0.48) m/s, graclient pressure (8.17+6.16) mm Hg. Mild aortic regurgitstion was present in 5 patients (10.6%), moderate aortic tegmgitafion in 2 pmieats (4.3%) and aevere aortic regurgitation in 1 petient (2.1%). The rate of free from regurgitation was 82.9%. Multiple logistic analyses identified the per esence of bicuspid aortic valve, enlargement of aortic annulus and age above 14 years as the risk factors for posterative aortic regurg itation. Conclusion The Ross procedure is a safe and effective procedure with good clinical results in mid-and long-term follow-up. However, the presence of bicuspid aortic valve, enlargement of aortic annulus and age above 14 years preoperatively were identified as the risk factors for postoperative aortic regurgitation.     

The use of telescoping guide catheters for coronary sinus cannulation and sub-selecting tributaries in left ventricular lead placement

Introduction Failure to enter the coronary sinus (CS) with a guiding catheter and entering its tributaries remains challenging in left ventricle (LV) pacing lead implants for cardiac resynchronization therapy (CRT). A dual telescoping catheter system (8F outer/6F inner) is designed to provide the ability to adjust the catheter curve size, shape and/or reach to the patients’ anatomy avoiding the need for catheter change. Methods Five different designs for CS cannulation were randomly tested in 64 patients scheduled for CRT device implant. Results In 33 consecutive patients three adaptable telescoping guiding catheter systems were tested per patient, the adaptable catheters had higher overall cannulation success rates (68, 63 and 62%) compared to the fixed shape catheter (46%) and an greater cannulation success rate when the CS location was not known (70, 53 and 72% vs 33% for the fixed shape). In a second group of 31 CRT patients the two telescoping catheters had similar high levels of success (71–80%), with or without using the inner catheter. Conclusions The telescopic system is adaptable to a wide range of anatomical variations in patients and can result in a higher CS cannulation success rate due to its adjustability in the RA in search for the CS ostium. On top of this the inner catheter allows for sub-selecting the CS tributaries.     

Structure function interface with sequential shortening of basal and apical components of the myocardial band

Objective: To mechanically test the intact cardiac structure to determine the sequence of contraction within the myocardial mass to try to explain ejection and suction. Methods: In 24 pigs (30–85 kg), segment shortening at the site of sonomicrometer crystals was continuously recorded. The ECG evaluated rhythm, and Millar pressure transducers measured intraventricular pressure and dP/dt. Results: Study of segment shortening defined a sequence of contraction within the myocardial mass, starting at the free wall of the right ventricle and on the endocardial side of the antero-septal wall of the left. Crystal location defined underlying contractile trajectory; transverse in right ventricle followed by basal posterior left ventricle, and from the endocardial anterior wall to the posterior apical segment and finally to the epicardial side of the anterior wall. Mean shortening fraction averaged 18±3%, with endocardial exceeding epicardial shortening by 5±1%. Epicardial segment crystal displacement followed endocardial shortening by 82±23 ms in the anterior wall, and finished 92±33 ms after endocardial shortening stopped, time frame that matches the interval of fast drop of ventricular pressure and the start of suction. Conclusions: Crystal shortening fraction sequence followed the rope-like myocardial band model to contradict traditional thinking, with two starting points of excitation–contraction, the right anterior free wall of the right ventricle, and the endocardial side of the anterior wall. Active suction may be due to active shortening of the epicardial fibers of the anterior wall, because relaxation was not detected when both mitral and aortic valves were closed during the interval previously termed ‘isovolumetric relaxation’.