Identification of Arterial Wall Dynamics in Conscious Dogs

Viscoelastic properties determine the dynamic behaviour of the arterial wall under pulsatile pressure and flow, suggesting time- or frequency-dependent responses to changes in wall stress and strain. The objectives of the present study were: (i) to develop a simplified model to derive simultaneously the elastic, viscous and inertial wall moduli; (ii) to assess Young's modulus as a function of frequency, in conscious, chronically instrumented dogs. Parametric discrete time models were used to characterise the dynamics of the arterial system based on thoracic aortic pressure (microtransducer) and diameter (sonomicrometry) measurements in control steady state and during activation of smooth muscle with the alpha-adrenoceptor agonist phenylephrine (5 microg kg(-1) min(-1), I.V.), in eight conscious dogs. The linear autoregressive model and a physically motivated non-linear model were fitted to the input-output (stress-strain) relationship. The aortic buffering function (complex Young's modulus) was obtained in vivo from the identified linear model. Elastic, viscous and inertial moduli were significantly increased from control state ((44.5 +/- 7.7) x 10(4) Pa; (12.3 +/- 4.7) x 10(4) Pa s; (0.048 +/- 0.028) x 10(4) Pa s(2) ) to active state ((85.3 +/- 29.5) x 10(4) Pa, P < 0.001; (22.4 +/- 8.3) x 10(4) Pa s, P < 0.05; (0.148 +/- 0.060) x 10(4) Pa s(2), P < 0.05). These moduli, obtained using the linear model, did not present significant differences compared with those derived using the non-linear model. In control conditions, the magnitude of the normalised complex Young's modulus was found to be similar to that reported in previous animal studies ranging from 1 to 10 Hz. During vascular smooth muscle activation, this modulus was found to be increased with regard to control conditions (P < 0.01) in the frequency range used in this study. The frequency-dependent Young's modulus of the aortic wall was obtained for the first time in conscious, unsedated dogs. The parametric modelling approach allows us to verify that vascular smooth muscle activation increases the elastic, viscous and inertial moduli with the advantage of being able to track their time evolution. Furthermore, under activation, the aortic wall remains stiff in the physiological frequency range, suggesting the impairment of the arterial buffering function. Experimental Physiology (2001) 86.4, 519-528.     

Consequences of Myocardial Structural Adaptation on Left Ventricular Compliance and the Frank-Starling Relationship in Spontaneously Hypertensive Rats

The Frank-Starling relationship of hearts from adult spontaneously hypertensive rats (SHR, Okamoto 1969), representing the established phase of hypertension, and of young SHR, representing the initial phase of hypertension, was investigated by using the isoloated working heart preparation. In the “normal” diastolic pressure range (5 to 10 cm H₂O), the left ventricle of both SHR groups displayed significantly reduced stroke volumes compared with hearts of normotensive controls (NCR); the degree of reduction being proportional to the left ventricular hypertophy. This is suggested to be due to a reduced left ventricular diastolic compliance in SHR, as indicated by direct measurements of ventricular wall thickness and end-diastolic volumes in arrested hearts exposed to different end-diastolic filling pressures. Such a progressive shift of the Frank-Starling relationship to the right with duration of hypertension could, in combination with the gradual development of “Structural autoregulation” of the precapillary resistance vessels, constitute dominating factors in shifting the hemodynamic situation in labile hypetension into that characterizing the established, or “fixed”, State of hypertension.     

Regional Blood Flow in the Left Ventricular Wall of Dogs with a Graded Coronary Artery Stenosis

Blood flow in the circumflex branch of the left coronary artery was recorded by electromagnetic flowmeter. In the area supplied by this branch vasodilatation was produced by progressive constriction until the diastolic reactive hyperemic response to 10 s occlusion disappeared (“optimum” stenosis). This degree of stenosis was accompanied by a 20% decrease in diastolic circumflex flow, while systolic flow remained unchanged. The distribution of blood flow in the left ventricular free wall was evaluated at “optimum” stenosis by counting activity in tissue blocks following bolus injection of Xe-133 into the aortic root. When Xe-133 was injected immediately after occlusion of the left anterior descending branch the Xe-133 concentration of the endocardial part of the area supplied by the circumflex branch was about half the concentration in the epicardial part. The concentrations in the two parts did not, however, differ significantly when occlusion of the left anterior descending branch was omitted. This indicates that the endocardial blood flow reserve is lower than the epicardial, and that, yet, a preferential fall in blood flow in the endocardial part of a post-stenotic area can be rapidly eliminated when blood supply from a neighbouring artery is available.     

不同起搏部位对左心室重构及左心收缩功能的影响

目的 研究右室间隔起搏及传统右室心尖部起搏对左心室重构及左心收缩功能的影响。方法 收集2013年1月~2015年5月曾于亳州市人民医院心内科行双腔起搏器植入术且随访资料完整的患者共63例,其中右室间隔起搏组共32例,右室心尖部起搏组共31例,观察两组术前与术后1年左室舒张末容积、左室射血分数、及血清NT-proBNP水平变化。结果 两组起搏器植入术前血清NT-proBNP水平及左室舒张末期内径和左室射血分数比较,差异无统计学意义（P＞0.05）,术后1年随访检测血清NT-proBNP水平,右室心尖部起搏组较右心室间隔部组升高（P＜0.05）;右心室间隔部起搏组术后左室舒张末期内径和左室射血分数与术前比较,差异无统计学意义（P＞0.05）;右室心尖部起搏组术后1年左室舒张末期内径较术前增大,左室射血分数减小（P＜0.05）。结论 相较于传统的右室心尖部起搏,右室间隔部起搏更能保证心室正常的电活动顺序,且对左室收缩功能的影响较小。     

Distribution of Coronary Blood Flow in the Left Ventricular Wall of Dogs Evaluated by the Uptake of Xe-133

The distribution of coronary blood flow was estimated in anesthetized dogs by counting the activity in tissue blocks of the left ventricular free wall immediately after bolus injection of Xe-133 into the aortic root. No differences in the uptake of isotope were observed between the apex and the base of the heart; between areas supplied by the anterior descending and circumflex branches of the left coronary artery; or between the endo- and epicardial halves of the wall. In most experiments a bolus injection of the isotope into the left coronary artery was followed by a difference in activity between areas supplied by the left anterior descending and left circumflex branches. This indicated inadequate mixing of blood and isotope in the main stem of the artery. The uneven distribution did not result in differences between the epi- and endocardial activity concentrations. The results from one normal, anesthetized dog in which tissue activities were measured after constant rate infusion of Xe-133 into the left coronary artery for 8 min were in accordance with the general assumption of equal epiand endocardial volumes of distribution (values of Zs).     

侧脑室微量注射生长抑素对清醒狗胃窦运动的影响

借助缝植于胃窦部的应力传感器,对清醒狗胃窦收缩运动进行记录,观察侧脑室微量注射生长抑素后对胃运动的影响。实验结果发现侧脑室注射0.05μg生长抑素,可促使胃窦收缩运动明显增强,这种增强效应主要表现在收缩波振幅的增强,而收缩波数目无明显变化,在给药后的1小时内,胃窦平均收缩波振幅较给药前增加了42.42±10％。外周静脉灌流阿托品可阻断生长抑素的这种作用,表明生长抑素的中枢作用经胆碱能神经纤维传出。     

肾移植后移植肾血流灌注与左心功能相关性分析

目的探讨移植肾彩色多普勒能量图(CDE)与左心功能的关系和临床意义.方法于肾移植前2次血透之间及肾移植后半年内和半年以后,采用CDFI超声诊断仪观察移植肾CDE血流灌注情况并分为4级,同时检测肾移植前后患者心功能指数,对比分析CDE与左心功能指数的相关性.结果 CDE移植肾内血流灌注满意,心功能超声测值有显著改善(p<0.05);而CDE移植肾内血流灌注不满意,心功能超声测值无显著改善(p>0.05).结论 CDE移植肾内血流灌注变化与左心功能改善呈正相关.同时随时间的推移心功能各项指标均有明显改善.     

肾移植后移植肾血流灌注与左心功能相关性分析

目的　探讨移植肾彩色多普勒能量图 (CDE)与左心功能的关系和临床意义 .方法　于肾移植前 2次血透之间及肾移植后半年内和半年以后 ,采用CDFI超声诊断仪观察移植肾CDE血流灌注情况并分为 4级 ,同时检测肾移植前后患者心功能指数 ,对比分析CDE与左心功能指数的相关性 .结果　CDE移植肾内血流灌注满意 ,心功能超声测值有显著改善 (p <0 .0 5 ) ;而CDE移植肾内血流灌注不满意 ,心功能超声测值无显著改善 (p >0 .0 5 ) .结论　CDE移植肾内血流灌注变化与左心功能改善呈正相关 .同时随时间的推移心功能各项指标均有明显改善     

红豆杉多糖对犬心肌缺血-再灌注损伤左室舒张功能及心肌梗死质量的影响

目的 观察红豆杉多糖对心肌缺血-再灌注损伤(MIRI)导致的左室舒张功能及心肌梗死质量的影响,为其临床应用提供实验依据.方法 将30只比格犬随机分为假手术组、模型组、红豆杉多糖低剂量、高剂量组、卡维地洛对照组,每组6只,分别给药7 d后,建立MIRI模型.用BIOPAC十六道生理记录仪生物信号分析系统观察并记录缺血前、缺血后5、30、60 min以及再灌注10、30、60、90 min及灌注120 min等9个时间点的左室舒张末压(LVEDP)、左室内压最大下降速率(LV-dp/dtmax);TTC染色法测定心肌梗死质量占全心或左心室肌质量的百分率.结果 模型组、红豆杉多糖低、高剂量组、卡维地洛组缺血5 min及模型组缺血30 min、灌注30、60 min时LVEDP较假手术组显著增高(P<0.05),高剂量组灌注10 min时LVEDP较缺血前显著增高(P<0.05);模型组缺血30、60 min,灌注10、30、60、90、120 min各时间点LV-dp/dtmax绝对值较假手术组显著降低(P<0.05);低剂量组LV-dp/dtmax绝对值在缺血60 min,灌注30、60、120 min时显著高于模型组(P<0.05);高剂量组LV-dp/dtmax绝对值在灌注90、120 min时显著高于模型组(P<0.05).高剂量组的梗死区质量占全心质量的百分比、梗死区质量占左室质量的百分比均较模型组显著降低(P<0.05).结论 红豆杉多糖对MIRI导致的心肌舒张功能障碍及心肌损伤具有保护作用.     

Predictors of Increased Left Ventricular Filling Pressure in Dialysis Patients with Preserved Left Ventricular Ejection Fraction

Aim

To study the left and right ventricular function and to assess the predictors of increased left ventricular (LV) filling pressure in dialysis patients with preserved LV ejection fraction.

Methods

This study included 63 consecutive patients (age 57 ± 14 years, 57% women) with end-stage renal failure. Echocardiography, including tissue Doppler measurements, was performed in all patients. Based on the median value of the ratio of transmitral early diastolic velocity to early myocardial velocity (E/E’ ratio), patients were divided into 2 groups: the group with high filling pressure (E/E’>10.16) and the group with low filling pressure (E/E’≤10.16).

Results

Compared with patients with low filling pressure, the group of patients with high filling pressure included a higher proportion of diabetic patients (41% vs 13%, P = 0.022) and had greater LV mass index (211 ± 77 vs 172 ± 71 g/m³, P = 0.04), lower LV lateral long axis amplitude (1.4 ± 0.3 vs 1.6 ± 0.3 cm, P = 0.01), higher E wave (84 ± 19 vs 64 ± 18cm/s, P < 0.001), lower systolic myocardial velocity (S’:8.6 ± 1.5 vs 7.0 ± 1.3 cm/s, P < 0.001), and lower diastolic myocardial velocities (E’: 6.3 ± 1.9 vs 9.5 ± 2.9 cm/s, P < 0.001; A’: 8.4 ± 1.9 vs 9.7 ± 2.5 cm/s, P = 0.018). Multivariate analysis identified LV systolic myocardial velocity – S’ wave (adjusted odds ratio, 1.909; 95% confidence interval, 1.060-3.439; P = 0.031) and age (1.053; 1.001-1.108; P = 0.048) as the only independent predictors of high LV filling pressure in dialysis patients.

Conclusions

In dialysis patients with preserved left ventricular ejection fraction, reduced systolic myocardial velocity and elderly age are independent predictors of increased left ventricular filling pressure.Cardiovascular disorders are the main cause of mortality and morbidity in patients with end-stage renal failure who are in regular hemodialysis programs (1,2). The left ventricular (LV) hypertrophy is a common finding in these patients. It reflects a physiological response to pressure and volume overload (3) and positively correlates with cardiovascular mortality (4). LV hypertrophy is frequently associated with LV dilatation and reduced systolic function (5). An increased incidence of atherosclerotic cardiovascular events in these patients has also been reported (6). Systolic dysfunction and LV hypertrophy have been identified as the best predictors of outcome in dialysis patients (4,7,8). However, the conventional systolic dysfunction appears in the late stages of the chronic renal failure (9).In contrast to conventional echocardiography, tissue Doppler imaging of the myocardial velocities overcomes the load dependence of diastolic parameters (10). The ratio of transmitral early diastolic velocity (E) to early myocardial velocity (E’) (E/E’ ratio) has been shown to be an accurate method of the LV filling pressure estimation (8) and the best predictor of LV diastolic filling in various cardiac pathologies (11,12), thereby serving as one of the best predictors of outcome in heart failure patients (13-15) and patients with end-stage renal disease (16).The aims of this study were to investigate the left and right ventricular function in patients with end-stage renal disease and preserved LV ejection fraction and to assess the predictors of increased LV filling pressure in these patients.     

Variable Unstressed Volume Keeps Normal Distributions of Canine Left Ventricular Contractility and Total Mechanical Energy under Atrial Fibrillation

We have reported that the contractility index (E(max)) and the total mechanical energy (PVA) of arrhythmic beats of the left ventricle (LV) distribute normally in canine hearts under electrically induced atrial fibrillation (AF). Here, E(max) is the ventricular elastance as the slope of the end-systolic (ES) pressure-volume (P-V) relation (ESPVR), and PVA is the systolic P-V area as the sum of the external mechanical work within the P-V loop and the elastic potential energy under the ESPVR. To obtain E(max) and PVA, we had to assume the systolic unstressed volume (V(o)) as the V-axis intercept of the ESPVR to be constant despite the varying E(max), since there was no method to obtain V(o) directly in each arrhythmic beat. However, we know that in regular stable beats V(o) decreases by approximately 7 ml/100 g LV with approximately 100 times the increases in E(max) from ~0.2 mmHg/(ml/100 g LV) of almost arresting weak beats to approximately 20 mmHg/(ml/100 g LV) of strong beats with a highly enhanced contractility. In the present study, we investigated whether E(max) and PVA under AF could still distribute normally, despite such E(max)-dependent V(o) changes. The present analyses showed that the E(max) changes were only approximately 3 times at most from the weakest to the strongest arrhythmic beat under AF. These changes were not large enough to affect V(o) enough to distort the frequency distributions of E(max) and PVA from normality. We conclude that one could practically ignore the slight E(max) and PVA changes with the Emax-dependent V(o) changes under AF.     

p38 Mitogen-Activated Protein Kinase Inhibition Decreases TNFalpha Secretion and Protects Against Left Ventricular Remodeling in Rats with Myocardial Ischemia

The purpose of this study was to test our hypothesis that p38 mitogen-activated protein kinase (p38 MAPK) inhibitor SB203580 may favorably affect tumor necrosis factor alpha (TNFα) secretion and left ventricular (LV) remodeling after myocardial ischemia (MI). The left anterior descending coronary artery (LAD) was ligated to produce anterior MI in 40 rats that were randomly divided into two groups: p38i group (n = 24) and MIR group (MI rat models, n = 24). A sham operation group without LAD ligation (Sham, n = 16) was also studied. SB203580 (2 mg/kg) and saline was injected i.p. once every 3 days in the first two groups, respectively. One and six weeks after MI, cardiac function, myocardial fibrosis, the cardiac expressions of phosphorylated p38 MAPK (p-p38 MAPK), TNFα, alpha smooth muscle actin (αSMA) and collagen I, the ultramicrostructure of the myocardium were examined by echocardiography, histological staining, western blot, immunohistochemical staining, transmission electron microscope (TEM), respectively. Treatments with SB203580 suppressed myocardial fibrosis and LV remodeling, as well as attenuated the expressions of p-p38-MAPK, TNFα, αSMA and collagen I as compared with the MIR. In conclusion, SB203850 has an effect of inhibiting inflammation-induced fibrosis, which leads to attenuation of LV remodeling.     

Successful Resection of a Giant Left Ventricular Pseudoaneurysm Developed Later after Mitral Valve Replacement

We present a case of successful surgical resection of a giant left ventricular (LV) pseudoaneurysm that developed 5 yr after mitral valve replacement (MVR). A 59-yr-old female was admitted with exertional chest pain radiating to left arm and back. 64-slice multidetector computed tomography (MDCT) revealed significant stenosis on the ostium of the first diagonal branch of the left anterior descending coronary artery and also a huge pseudoaneurysm compressing the right atrium and the inferior vena cava. She underwent resection of the pseudoaneurysm, and the pseudoaneurysm tunnel was repaired from the inside of LV cavity by removing the previously inserted prosthetic valve, followed by redo MVR together with coronary arterial bypass grafting (CABG) for a single-vessel disease. At the 6-month follow-up, the patient continued to do well without any complications.     

Effects of Long-term Right Ventricular Apical Pacing on Left Ventricular Remodeling and Cardiac Function

Objective： To investigate the impacts of long-term right ventricular apical pacing on the ventricular remodeling and cardiac functions of patients with high-grade and third-degree atrioventricular blockage with normal heart structures and cardiac functions. In addition, we provide many evidences for choosing an optimal electrode implantation site.Methods： Study participants included patients who were admitted for pacemaker replacements and revisited for examinations of implanted pacemakers at outpatient. Pacemakers were implanted to treat high-grade and third-degree atrioventricular blockage. At the time of pacemaker implantation, patients had normal cardiac functions and showed no serious heart diseases or cardiac dilatation. The durations from the implantation to follow-up were more than 5 years. The pacing rate was higher than 80%. Patients with a left ventricular ejection fraction （LVEF） 〈 50% and a left ventricular end-diastolic diameter （LVEDD） 〉 55 mm were excluded. Ventricular remodeling was defined as follows：increase of LVEDD by 10% and a reduction of LVEF by 25% for five years after implantation. Cardiac functions were evaluated according to New York Heart Association （NYHA） classification.Results：A total of 82 patients with a mean age of （66.97±13.19） years （range, 12 to 91 years old）,among which 39 male and 43 female were enrolled in this study. The average duration between two assessments was 8.7 years （104.4 months）. Before pacemaker implantation, the average left atrial diameter （LA）, LVEDD and LVEF were 37.0 mm, 50.23 mm and 64.87%, respectively. After the implantation, these values were 39.39 mm （P=0.000163）, 50.82 mm （P=0.177842） and 60.50% （P=0.000104）, respectively. Four patients （4.87%） had ventricular remodeling with deteriorations of cardiac function, three of which had anterior wall myocardial infarction after implantation and one had type II diabetes. Clinical symptoms of heart failure were not found among the patients who did not exhibit ventricular remodeling. Conclusion： Through a long-period follow-up study, we found that long-term right ventricular apical pacing in patients with normal heart structure and cardiac function would not generally cause ventricular remodeling and clinical deteriorations of cardiac function. Right ventricular apical is a safe and effective site for pacing electrode wire implantation.     

Effects of Stimulation of the Insular Cortex on Execution of the Antrofundal Reflex in Conscious Dogs

Neuroanatomical studies demonstrated the existence of direct descending projections from the insular cortex to the area of the solitary tract nucleus responsible for mediating the vagovagal reflexes of the proximal part of the gastrointestinal tract. These studies provided grounds for suggesting that one of the mechanisms mediating the influences of the insular cortex on stomach function may be modulation of its vagovagal reflex reactions, one of which is the antrofundal inhibitory reflex. Experiments on conscious dogs were performed to study the effects of electrical stimulation of the insular cortex on execution of the antrofundal gastric reflex in conditions of intermittent gastrointestinal tract activity during fasting. Stretching of the walls of the antral segment of the stomach during the active period of intermittent gastric activity led to suppression of contractions in the fundal segment. Electrical stimulation of the insular cortex was found to prolong this reflex reaction. Thus, one result of activation of the insular area of the cortex is enhancement of the inhibitory vagovagal gastric reflexes, in all probability occurring as a result of modulation of neurotransmission in the vagovagal reflex arc system.     

山羊心室条索的形态学特征

目的　观察山羊心室条索的解剖学和组织学特征。方法　对 82只成年山羊左右心室的游离条索进行解剖学观测 ,取 15例心脏的左心室 2 3条 ,右心室 17条条索 ,进行常规石蜡切片 ,HE和Masson染色 ,光镜下观察。结果　山羊左室条索的出现率为 95 12 % ,右心室出现率为 80 4 9% ,右心室条索的出现率明显低于左心室(P <0 .0 5 )。左心室条索以直条者较多 ,其次是一端和两端分叉型 ,少数呈网状。右心室条索的形态相对简单 ,网状和两端分叉型比较少见。左右心室条索直径大多小于 1mm。右室条索平均长 1 2 4± 0 5 0mm ,右心室长 0 93± 0 4 5mm ,98%的条索内含Pukinje细胞 ,2 %含心肌细胞。 结论　山羊左右心室腔内均存在游离条索 ,左心室多于右心室 ,条索内含有Pukinje细胞     

高血压病患者不同左室构型与胰岛素抵抗的相关性

目的探讨高血压患者胰岛素抵抗对左室构型的影响。方法对高血压组164例进行常规心脏超声、空腹葡萄糖（FBG）、空腹胰岛素（FIN）、血脂检查。采用胰岛素敏感指数（HOMA-IR）作为评价胰岛素抵抗指标,按Gnanu分类法将高血压组划分为正常构型、向心性重构组、向心性肥厚组和离心性肥厚组。采用组间比较、相关性分析等统计学方法进行评价。结果高血压患者按左室重量指数（LVMI）分组,两组间空腹胰岛素及胰岛素抵抗差异无统计学意义（P〉0.05）;但按相对室壁厚度（RWT）分组,空腹胰岛素及胰岛素抵抗差异具有统计学意义（P〈0.05）。并且向心性重构组和向心性肥厚组明显高于正常构型组（P〈0.05）,而离心性肥厚组与正常构型组比较差异无统计学意义（P〉0.05）。逐步回归分析显示LVMI与体重指数、收缩压和舒张压呈正相关（P〈0.05～P〈0.01）,RWT与HOMA-IR呈负相关（P〈0.05）。结论胰岛素抵抗可能是高血压患者合并左室肥厚的重要影响因素之一,改善胰岛素抵抗有利于高血压患者左室肥厚的防治。     

Reversibility and Pathohistological Basis of Left Ventricular Remodeling in Hibernating Myocardium

The phenomenon of left ventricular (LV) remodeling with dilatation, wall thinning, and increased muscle mass has previously been reported in pigs with 7-day myocardial hibernation. This study investigated cellular and extracellular basis and reversibility of the structural LV remodeling with hibernating myocardium. Five groups of pigs were included: Group A: 7-day myocardial hibernation with a fixed coronary stenosis; Group B: 7-day hibernation with subsequent 3-week reperfusion by release of the stenosis; Group C: control group with sham operation; Group D: 24-hour myocardial hibernation to define structural mechanism of initial wall thinning in the hibernating region without confounding factors of cell loss or hypertrophy, Group E: 4-week myocardial hibernation to exclude the possibility of spontaneous regression of LV remodeling with hibernation. LAD flow decreased by 38 ± 12% (p < 0.01) with a significant decrease in systolic wall thickening at 7 days of hibernation with severe coronary stenosis (Group A). End-diastolic wall thickness decreased by 19% (p < 0.01) accompanied by a decrease in myocyte number across the wall (44%) and in myocyte density (24%), a significant increase in myocyte width (17%), a mild increase in interstitial tissues in hibernating region, and significant increases in LV diastolic volume and in LV mass at 7 days. After reperfusion (Group B), LV volume decreased, LV ejection fraction improved, and myocyte hypertrophy regressed with a decreased LV mass index without a significant change in interstitial tissue. LV remodeling progressed with further increases in LV volume, mass, and interstitial fibrosis in 4-week hibernation. In pigs undergoing 24 hours of myocardial hibernation (Group D), end-diastolic LV wall thickness decreased significantly in the hibernating region with a proportional decrease in the transmural myocyte number but without changes in myocyte width, myocyte density, or interstitial tissues. Therefore, progressive gross LV remodeling associated with hibernating myocardium is accompanied by increasing myocyte hypertrophy and interstitial fibrosis. In hibernating myocardial region, wall thinning is proportional to a decreased myocyte number across the LV wall, indicating slippage of myocytes as a preponderant mechanism for the wall thinning. Myocyte hypertrophy develops within 7 days in hibernating myocardium, causing an increase in LV mass. These changes are partially reversible after reperfusion.     

冠脉介入治疗后心肌梗死区灌注程度及存活对左室重构及功能的影响

评价冠脉介入治疗（PCI）后核素显像心肌梗死区灌注程度及存活对左室重构及功能的影响。选取20例急性前壁心肌梗死患者,男18例,女2例。梗死后20h内,梗死相关血管已接受冠状动脉介入治疗,冠脉血流正常。所有患者PCI术后10天内接受静息状态下双核素心肌显像（心肌灌注及心肌代谢显像）。根据基线梗死区灌注减低程度和心肌有无存活,分为两组,通过超声心动观察不同组患者12个月后左室舒张末直径（LVEDD）及左室收缩功能（LVEF）的变化,观察梗死区心肌存活状态及灌注情况对于左室重构的影响,间接反映其对自身心肌干细胞修复功能的影响。结果表明,梗死心肌有存活的患者（n=10）与无存活组（n=10）相比,两组12个月后LVEDD都无明显变化。梗死心肌有存活的患者LVEF有所改善,43.6±7.83 vs.46.79±12.68,无存活组LVEF轻度下降,39.10±8.71 vs.37.70±7.57,P〉0.05。梗死区灌注减低程度不同的两组患者PCI术后12个月,LVEDD都无明显变化。LAD PER%〈50%组（n=9）LVEF值有所改善,39.89±10.19%vs.42.22±13.54%,但变化不具有显著性,P〉0.05;LAD PER%〉50%组（n=11）LVEF值无改善,并可见轻度下降,42.55±6.86%vs.41.20±8.32%。LAD PER%〈50%且同时梗死区有存活心肌的患者（n=5）LVEF改善明显,上升了4.8%,与LAD PER%〉50%且同时梗死区无存活心肌的患者（n=6）相比具有统计学意义,P=0.029。结论：急性前壁心肌梗死并行PCI治疗的患者,心肌灌注程度不同与梗死区心肌是否有存活都对患者的左室重构改善无明显影响,但心肌灌注程度较好的患者和有心肌存活的患者左室收缩功能都有轻度改善;尤其值得注意的是,在心肌灌注程度较好,并且有存活心肌存在的情况下,心功能改善明显。而相对梗死区灌注差且无心肌存活的患者,12个月后,心功能减低,左室重构更加明显。