激光心肌血管重建术治疗心肌缺血后左室形态和功能表现

作者采用钕钇铝石榴石（Ｎｄ：ＹＡＧ）激光直接心肌血管重建术观察对左室形态学和功能学的远期影响。１２只犬完全随机分力实验组（ＥＧ）和对照组（ＣＧ）。左室造影显示：ＥＧ的左室整体和局部射血分数（ＴＥＦ，ＡＥＦ）和左室短轴径缩短率（△Ｄ）均高于ＣＧ（Ｐ＜０．０５）：ＥＧ有２只犬显示左室前壁运动减弱，ＣＧ全部大显示左室前壁室壁瘤形成：左室舒张终末压（ＬＶＥＤＰ）在ＥＧ为－０．０６±０．８６ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）．在ＣＧ为０．３６±０．７３ｋＰａ（Ｐ＞０．０５）。ＳＰＥＣＴ显示：ＣＧ全部犬发生透壁性心肌梗塞，ＥＧ仅１只犬发生心内膜下心肌埂塞（Ｐ＜０．０１）。结论：左室造影和ＳＰＥＣＴ可用于检测心肌血管重建术后的效果；Ｎｄ：ＹＡＧ激光用于直接心肌血管重建术是一种有效可行的方法。     

超声心动图在二尖瓣球囊成形中的应用价值

目的：应用超声心动图检查方法估价二尖瓣球囊成形术的疗效。材料和方法：选择１９９１０１～１９９５０４，２５例风湿性二尖瓣狭窄拟行二尖瓣球囊扩张患者于术前４８小时，术后立即及５～７天，部分患者于术后３个月，６个月及１年进行超声心动图随访观察。结果：二尖瓣球囊扩张后检查二尖瓣口面积由术前０８５±０２０ｃｍ扩大至１６９±０３０ｃｍ；瓣下最大血流速度（Ｖｍａｘ）由（２３５±０３９）ｍ／ｓ降至（１６０±０３３）ｍ／ｓ；ＰＧｍａｘ及ＰＧｍｅａｎ分别由术前（２９±１０）ｋＰａ及（１８±０８）ｋＰａ降至（１４±０５）ｋＰａ及（０６±０３）ｋＰａ。本组术后房间隔穿刺部位缺口以４～６ｍｍ多见，２３例（９２％）出现房水平左向右分流，２例１年检查仍存在分流。术后再狭窄最早出现时间为３个月３例（３／１７），６个月１例（１／１１）。结论：本组２５例二尖瓣球囊成形患者均获得成功，其效果满意。超声心动图可用于评价二尖瓣球囊成形术的效果并可及时检出其并发症。     

正加速度对飞行员血浆降钙基因相关肽、内皮素水平和肾功能的影响(英文)

为观察正加速度（＋Ｇｚ）对飞行员血浆降钙素基因相关肽、内皮素及肾功能部分指标的影响。２０名飞行员不穿抗荷服，在离心机＋２．５Ｇｚ和＋３．０Ｇｚ分别作用１０ｓ，中间休息５ｍｉｎ。暴露前后２０ｍｉｎ两次抽肘静脉血。结果＋２．５Ｇｚ，＋３．０Ｇｚ暴露后，血浆降钙基因相关肽和内皮素的相关系数ｒ＝０．７７２（Ｐ＜０．０１）。结论是＋２．５Ｇｚ，＋３．０Ｇｚ能增长血浆中ＣＧＲＰ、内皮素。含量不会造成临床肾功能损害     

离心机训练矫治+Gz耐力不良的高性能战斗机飞行员

目的 矫治两名＋Ｇｚ耐力不良的高性能战斗机飞行员。方法在离心机上高＋ＧＺ负荷下训练抗荷动作（ＡＧＳＭ）和加压呼吸（ＰＢＧ）动作。结果 ＡＧＳＭ的抗荷效果提高３．０－３．２５Ｇ,加压呼吸了系统的抗荷效果提高２．７５－３．０Ｇ,综合耐力比基础耐力高４．２５－４．５Ｇ,两人均顺利通过８Ｇ１０Ｓ的ＳＡＣＭ＋ＧＺ曲线,达到训练标准。     

新型侧管式抗荷装备与抗荷动作的综合防护性能

目的对新型侧管式抗荷装备与抗荷动作的综合防护性能进行研究, 探讨采用二者联合的方案对８ Ｇ１０ ｓ（增长率为２ Ｇ／ｓ）高Ｇ 进行防护的可行性。方法在离心机上, ＋ Ｇｚ 增长率为２ Ｇ／ｓ, 先测定９ 名飞行学员的基础＋ Ｇｚ 耐力, 其中５ 名飞行学员采用新型侧管式抗荷服（ＮＫＨ） ＋ 新型抗调器（ＮＫＴ）＋ Ｌ１ 动作（Ｌ１）、另４ 名飞行学员采用新型侧管式代偿服（ＮＤＣ） ＋ ＮＫＴ＋ Ｌ１,测定出其最大＋ Ｇｚ 耐力。结果５ 名飞行学员采用ＮＫＨ＋ ＮＫＴ＋ Ｌ１ 时的最大＋ Ｇｚ 耐力为８．８０±０ ．２７ Ｇ, 比基础＋ Ｇｚ 耐力高出４．６０±０．４２ Ｇ（Ｐ＜０．０１） ;４ 名飞行学员采用ＮＤＣ＋ ＮＫＴ＋ Ｌ１ 时的最大＋ Ｇｚ 耐力为８．７５±０ ．５０ Ｇ, 比基础＋ Ｇｚ 耐力高出４．５０±０．４６ Ｇ（ Ｐ＜０ ．０１） 。结论飞行员采用新型侧管式抗荷装备与抗荷动作能够对８ Ｇ１０ ｓ（ 增长率为２ Ｇ／ｓ） 的高Ｇ 进行有效防护。     

创伤性脑干血肿3例

病例１男，２０岁，从４米高处跌下头部受伤，随即意识障碍，半小时后送入院。呈浅昏迷，双瞳０．３ｃｍ，光反应欠灵敏，右眼球下视，左眼正常，右侧上下肢活动少，双下肢病理征（＋），右额皮裂伤。ＧＣＳ评分８分。血压１６／１０ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ），...     

经皮单球囊与双球囊肺动脉瓣成形术的对比观察

作者对经皮单球囊肺动脉瓣成形术１７例和双球囊扩张４０例的效果进行比较。扩张前两组右室收缩压分别为１１．７６±３．９４ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）与１２．６１±４．３３ｋＰａ；跨瓣压差分别为８．１１±３．６８ｋＰａ与８．４０±４．６１ｋＰａ（Ｐ＞０．０５）。扩张后右室收缩压分别为６．４８±１．６６ｋＰａ与７．０５±３．４４ｋＰａ；跨瓣压差分别为２．０１±１．５１ｋＰａ与２．１５±１．７８ｋＰａ（Ｐ＞０．０５）。上述结果提示单球囊与双球囊扩张的效果相同。     

犬双后肢体高速投射物伤后肝脏的间接损伤及机理

目的：旨在观察高速投射物（ＨＶＰ）伤后早期肝脏结构功能变化及儿茶酚胺在其中的可能作用。方法：用Ｍ－１６步枪Ｍ１９３、直径５．５６ｍｍ弹丸，射击犬双后肢肌肉丰满处，于致伤时测定部分动物肝脏表面压力。动物观察２４小时，于伤前及伤后不同时间取血测有关指标，活杀时取肝组织测相应指标。观测指标主要有血浆ＡＬＴ、胆红素、白蛋白、ＭＤＡ、去甲肾上腺素（ＮＥ），肝组织ＮＥ、ＭＤＡ、ＡＴＰ及肝脏有效血流量（ＥＨＢＦ）。部分动物活杀时取肝组织做光、电镜检查。统计方法：结果用平均值±标准差表示，组间差别用ｔ检验作统计分析，部分指标间做相关分析。结果：（１）血压在伤后一直低于伤前。（２）致伤瞬间肝脏表面均测到明显压力［平均约４００ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）］。（３）伤道入口大小约０．２４±０．０２ｃｍ２，出口约５２．４±３９．８ｃｍ２。２４小时活杀动物时见伤口有脓性渗出物，伤口内软组织损伤严重，有大量坏死组织及血凝块。（４）光、电镜观察：见动物伤后肝脏有明显损伤表现。（５）动物伤后血浆ＡＬＴ、ＭＤＡ水平明显升高（Ｐ＜０．０５或Ｐ＜０．０１），２４小时时升高最明显，血浆白蛋白含量在２４小时时明显低于伤前（Ｐ＜０．０１），     

下体正压模拟推拉动作对＋GZ耐力的影响

目的 用单轴向离心机和下体正压模拟推拉动作,研究推拉动作对＋Ｇｚ耐力的影响。方法 ６名受试者着ＫＨ－３抗荷服充气３００ｍｍＨｇ（１ｍｍＨｇ＝０．１３３ｋＰａ）１ｍｉｎ,测定下体正压前、中、后血压（ＢＰ）、心率（ＨＲ）变化。在离心机上测基础耐力后,向抗荷服充气３００ｍｍ Ｈｇ、１ｍｉｎ放气后立即转动离心机,测松弛Ｇ耐力。结果 收缩压（ＳＢＰ）在下体正压中与下体正压前相比升高有显著性意义（Ｐ〈０．０１     

茶多酚对重复+Gz暴露大鼠脑脂质过氧化反应和肝肾功能的影响

观察重复＋１０Ｇｚ暴露对大鼠脑脂质过氧化反应和肝肾功能的影响以及天然抗氧化剂茶多酚（ＴＰ）的防护作用。方法２４只雄性Ｗｉｓｔａｒ大鼠随机等分为三组（ｎ＝８）：Ａ组（对照组）,Ｂ组（＋１０Ｇｚ组）和Ｃ组（ＴＰ组）。Ｂ、Ｃ组重复＋１０Ｇｚ暴露（每次３０ｓ,Ｇ增长率约为０．５Ｇ／ｓ,３次／ｄ,间隔＋１Ｇｚ１ｍｉｎ,３ｄ／ｗｋ,共４ｗｋ）,而Ａ组仅受＋１Ｇｚ作用。Ｃ组于＋Ｇｚ实验前约１ｈ灌胃给予ＴＰ（２００ｍｇ／ｋｇ）,另外两组给予等量蒸馏水。测定脑脂质过氧化反应、肝肾功能和血脂水平。结果与对照组相比,Ｂ组大脑皮层匀浆、线粒体和胞浆脂质过氧化反应明显增强（Ｐ＜０．０５）,血浆肌酐水平明显升高（Ｐ＜０．０１）;而ＴＰ对此过氧化反应具有显著抑制作用并明显降低血浆肌酐水平。各组间血清谷丙转氨酶活性、甘油三酯和总胆固醇水平无统计学差异。结论重复高＋Ｇｚ作用可引起脑自由基损伤并损害肾功能,而天然抗氧化剂茶多酚具有明显的保护作用。     

Effects of dipyridamole on the cardiovascular response to +Gz stress in miniature swine

Eight conscious female miniature swine experienced acceleration levels of 3, 5, and 7 +Gz before and after infusion of dipyridamole (1-2 mg.kg-1). Each animal was instrumented to measure ECG, heart level arterial pressure (AP), eye level arterial pressure (ELBP), left arterial pressure (LAP), heart rate (HR), and regional tissue blood flows. Each was also fitted with an abdominal anti-G suit which automatically inflated. Dipyridamole infusion had no direct effect on HR or LAP but AP was significantly reduced. All cardiovascular responses to +Gz were qualitatively similar before and after dipyridamole. Tachycardia always occurred. AP and CNS blood flow were maintained better prior to dipyridamole and AP always fell in proportion to acceleration intensity. +Gz was generally associated with increased blood flow to respiratory muscles and heart, decreased blood flow throughout the viscera and to the eyes. ELBP paralleled AP, but was always lower in direct proportion to the +Gz level. We conclude that dipyridamole reduces arterial pressure thus compromising the ability of the animal to sustain cerebral perfusion pressure (ELBP) during +Gz.     

Reflex heart rate response to variable onset +Gz

Rapid onset high sustained +Gz is a frequent requirement in air combat maneuvering. The cardiovascular response is inadequate to fully compensate for this rapid +Gz change. The rate of change in heart rate (HR) during gradual (0.1 G.s-1, GOR), rapid (1.0 G.s-1, ROR), and very high (6.0 G.s-1, VHOG) onset acceleration exposures to sustained (15 s) +7Gz, +8Gz, and +9Gz levels was measured in 81 healthy male subjects in a human centrifuge. The time (s) to reach maximum heart rate (T7) was measured as the time for the preacceleration exposure resting heart rate (RHR) to reach maximum heart rate (MHR). The change in heart rate upon reaching maximum +Gz level (delta HRA) from rest was calculated along with the change in HR from rest to the maximum heart rate achieved before maximum +Gz level was attained. During the ROR and VHOG runs, MHR was not achieved until after maximum +Gz level was attained. The change in heart rate from resting HR (immediately prior to acceleration) to the heart rate achieved at the onset of maximum +Gz level (delta HRA), decreased by 50% as the onset rate increased from GOR to ROR and VHOG. The delta HRB for very high onset rates exposures was significantly greater than that for ROR and GOR exposures. Acceleration exposure to levels of +7Gz and above (+7Gz, +8Gz and +9Gz) exhibited similar HR responses. VHOG to sustained +Gz stress levels of +7 to +9Gz for 15 s did not provide a sufficient length of time to allow maximum cardiovascular response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence and nature of electrocardiographic disorders in the dog after single and multiple exposure to +Gz

Pathological changes of the ECG were examined in 10 adult dogs exposed to +Gz once a day or 3 times a day for three days a week during 2 to 12 weeks. In response to acceleration all of the dogs developed ECG changes. The frequency and level of these disorders were dependent on the acceleration magnitude and the health state that varied during repeated exposure. These findings were used to develop a 5-score scale for measuring ECG disorders and to identify phase changes in acceleration tolerance during repeated exposure to +Gz. It was also demonstrated that animals can be specifically trained to tolerate sustained and high acceleration +Gz.     

Assisted positive pressure breathing for augmentation of acceleration tolerance time

The addition of assisted (chest counterpressure), positive pressure breathing (APPB) at 50 mm Hg (PPB50) and 70 mm Hg (PPB70) was compared to the current operational support of the G-suit and the anti-G straining maneuver (AGSM) without PPB (PPB0), during acceleration exposures of sustained 9 +Gz for 45 s and a 5-9 +Gz simulated aerial combat maneuver (SACM) to exhaustion. We selected 7 highly motivated male centrifuge subjects from a group of 31 volunteers. Positive pressure breathing was applied to the oronasal cavity with a Royal Air Force P/Q mask. Mask pressure was monitored continuously. Counterpressure was applied to the chest with a Canadian counterpressure garment at the same pressure as the mask. Lower body pressure was provided by a standard USAF G-suit inflated with the standard pressure schedule of 1.5 psi/G after 2.0 G. Positive pressure breathing was provided linearly in proportion to the +Gz level beginning at about 1.2 +Gz and reaching a peak of either 50 or 70 mm Hg (6.7 and 9.3 kPa, respectively) at 9 +Gz. Prepressurization (ready pressure) was used for both PPB (2.1 mm Hg) and G-suit (10.3 mm Hg) inflation. All subjects were monitored for heart rate and rhythm, SaO2 with an ear oximeter, inspired air flow, and rectus femoris electromyogram (EMG). Assisted positive pressure breathing provided a significant (p less than 0.01) increase in mean tolerance time at PPB50 (108%) and PPB70 (88%) compared to PPB0 during the 5-9 SACM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of a Reverse Gradient Garment for prevention of bed-rest deconditioning

A Reverse Gradient Garment (RGG) was used to intermittently induce venous pooling in the extremities of a magnitude similar to that seen in going from a lying to standing position during the course of a 15-d period of horizontal bed rest. Venous pooling failed to improve bed-rest-induced losses in +2.5 Gz and +3.0 Gz centrifugation tolerance or to prevent increased heart-rate responses to lower-body negative pressure (LBNP). Four subjects served as controls, four were treated. Tests during the 7-d recovery period showed fluid/electrolyte and body composition values to have returned to pre-bed-rest levels with continued depression of acceleration tolerance times (56% decreased at +2.5 Gz and 74% decreased at +3.0 Gz compared to pre-bed-rest levels) and exaggerated blood insulin response on glucose tolerance testing (blood insulin for treated group increased 95% at 1 h before bed rest and 465% during recovery). This study demonstrates that the physiologic changes after bed rest persist for significant periods of time. Acceleration tolerance time proved to be a sensitive test for the deconditioning process.     

Hypertension induced by repeated exposure to high sustained +Gz (HS + Gz) stress

The purpose of this study was to determine whether repeated exposure to high sustained +Gz (HS + Gz) stress induced persistent changes in the functional state of the cardiovascular system. Three groups of rabbits--centrifuged, restrained, and control--were studied. After being placed in the restraining system of the centrifuge, the animals were submitted three times in a row to 8-9 +Gz sustained for 40 s. This exposure was repeated three times a week for 3-6 weeks. Restrained animals were not exposed to HS + Gz. Control animals were not restrained. The two types of stress (centrifuge + restraint; restraint alone) determined the appearance of two types of arterial hypertension. Systolic arterial pressure (AP) and left ventricular pressure (LVP) significantly increased in restrained animals. The function of the cardiovascular system was more perturbed in centrifuged rabbits since the significant changes affected not only systolic AP and LVP but alos systemic diastolic AP and the maximum rate of rise of LVP. The myocardium of rabbits repeatedly subjected to HS + Gz exposures, except for those that suffered a fracture of the lumbar spine, was significantly glycogen-depleted.     

+Gz作用下心电图QT间期的改变及其意义

目的 探讨能否用ＱＴ间期来预测飞行员对＋Ｇｚ应激的反应情况。方法３７名空军 在人用离心机上经受峰值为４Ｇ的正向加速度作用,根据被试者对＋Ｇｚ应激反应的不同,将其分成Ａ组（反应良好组,ｎ＝１８）、Ｂ组（反应亢进组,ｎ＝１４）和Ｃ组（反应抑制组,ｎ＝１）。实验结束后测量＋Ｇｚ作用前、中、后心电图的ＱＴＵ是期和ＲＲＵ是期,并对能够测量出ＱＴ间期的３３人（８９．２％）的数据进行统计分析。结果 ＋Ｇｚ作用中     

Regional cerebral blood flow in conscious miniature swine during high sustained +Gz acceleration stress

The two major factors limiting performance during high +Gz acceleration stress are loss of vision, and loss of consciousness. These symptoms are believed to occur as a result of insufficient blood flow to the retina and brain. This study was conducted to determine the effects of +Gz stress on regional cerebral blood flow. Cerebral blood flow (CBF) was measured in 22 conscious, female, miniature swine with the radio-labeled microsphere technique. Acceleration exposures consisted of 60-S plateaus at +3Gz, +5Gz or +7Gz. Microsphere infusions were made before, during, 1.0-6.0 min after, and 10 min after +Gz. Blood flow to the retina was significantly decreased during exposure to +5Gz and ceased during exposure to +7Gz stress. Mean, resting control CBF was 34 +/- 4 ml/min/100 g. Exposure to +3Gz and +5Gz had no significant effect on CBF. Exposure to +7Gz appeared to cause a redistribution of CBF, with blood flow to the brain stem being preserved and flow to the cerebrum being diminished.     

The role of arterial elastance in ventricular-arterial coupling in normal gravity and altered acceleration environments

The role of physiological elastance (Ep) in maximizing external work (EW) transfer is not well understood and has not been investigated during microgravity and increased acceleration conditions. By better understanding this relationship, cardiovascular control mechanisms for meeting metabolic demands during normal gravity and altered acceleration stresses may be elucidated. Therefore, the objectives of this study were to determine the effect of Ep in maximizing EW of the left ventricle and to investigate this relationship during altered acceleration states. Ventricular and arterial parameters were estimated using established lumped parameter models from isolated beats of experimental data. These data were obtained during parabolic flight (0 and approximately 2 Gz) and centrifuge runs (approximately 1 to approximately 4 Gz) where acceleration was used to drive the cardiovascular system into a wide range of physiologic operating and coupling conditions. Parameter estimates at each Gz level were used in a series of computer simulations in which Ep was varied over a wide range to find the point of maximum EW for that coupling condition. Cardiac output and mean arterial pressure were maintained throughout the simulation process by adjusting heart rate. Results of the simulation showed that as arterial elastance decreased from its initially estimated (physiologic) value, external work increased slightly and as elastance increased, external work decreased. In particular, we found that the arterial elastance was set at a point near that which would produce maximal external work. In addition, it was found that altered Gz states may affect the Ep-EW relationship.     

Endurance training alters arterial baroreflex function in dogs

The present study was designed to determine whether 12 wk of daily exercise alter autonomic neural control of the heart during baroreflex stimulation in healthy dogs. We studied 16 untrained and 12 endurance-trained anesthetized dogs which were instrumented to measure arterial blood pressure (AP), carotid sinus baroreceptor pressure (CBP), electrocardiogram (ECG), heart rate (HR), and R-R interval (RR). The arterial baroreflex was studied during hypertension caused by i.v. bolus infusion of phenylephrine, hypotension caused by i.v. bolus infusion of nitroprusside, and bilateral carotid occlusion (BCO) in which carotid sinus pressure was reduced to 41 +/- 2 mm Hg (mean +/- SEM). Arterial baroreflex sensitivity, which was assessed by determining the change in heart interval (i.e., change in RR) per unit change in systolic AP (delta RR/delta AP), was significantly lower during the hypertensive challenge in the trained dogs compared to the untrained dogs (2.2 +/- 0.3 vs 6.8 +/- 1.5 ms.mm Hg-1, respectively). Similarly, the delta RR/delta AP was substantially lower during the hypotensive challenge in trained dogs vs the untrained dogs (1.2 +/- 0.3 vs 1.8 +/- 0.4 ms.mm Hg-1, respectively). In addition, the HR response to the BCO was significantly less in trained dogs (22 +/- 2 bpm) vs untrained dogs (32 +/- 5 bpm). The open-loop gain (Go), which was used to quantitate the effectiveness of the carotid baroreflex to increase mean systemic AP during BCO, was similar in both untrained and trained dogs (2.9 +/- 0.6 and 2.4 +/- 0.5, respectively). These data indicate that, while endurance training significantly reduces the HR component of the arterial baroreflex, the arterial pressure response apparently is not altered.