Perioperative hemodynamic study of patients undergoing abdominal surgery using pulse dye densitometry

BACKGROUND/AIMS: Pulse dye densitometry (PDD) using indocyanine-green (ICG) is a newly developed technique for monitoring cardiac output (CO), cardiac index (CI), circulating blood volume (BV) and ICG elimination rate (K-ICG). We measured hemodynamic changes during the perioperative period in patients undergoing digestive surgery to analyze relationships between hemodynamic changes and surgical procedures, blood loss, water balance and SIRS. METHODOLOGY: Eighty-seven patients who underwent gastrectomy (n=46) and colectomy (n=41) without postoperative complications were enrolled in this study. The corresponding data from 15 patients who underwent laparoscopic cholecystectomy were used as controls. CO, CI, BV and K-ICG were measured by PDD before operation, on the first postoperative day (POD 1), POD 3, POD 7 and POD 14. RESULTS: In all patients, CO and CI increased significantly until POD 3 compared with preoperative levels. BV on POD 1 decreased significantly compared to the preoperative level. K-ICG increased significantly until POD 14. Laparoscopic cholecystectomy resulted in less surgical stress than gastrectomy or colectomy as measured by hemodynamic changes. There were minimal differences in hemodynamics between the gastrectomy and colectomy groups. There were significant negative correlations between intraoperative blood loss and the [POD 1: preoperative values] ratios for CO, CI, BV or K-ICG. There was no correlation between changes in water balance from operation to POD 1 and [POD 1: preoperative value] BV ratio. CONCLUSIONS: An increase in CO and decrease in BV were observed at the early operative stage, especially in patients with systemic inflammatory response syndrome (SIRS). Interestingly, hepatic artery flow volume (K-ICG) remained high until POD 14. It is important to minimize intraoperative blood loss, since it markedly affects postoperative hemodynamics.     

Noninvasive etiologic diagnosis of cardiac amyloidosis using 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy.

OBJECTIVES: We investigated the diagnostic accuracy of 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy for differentiation of monoclonal immunoglobulin light-chain (AL) and transthyretin (TTR)-related cardiac amyloidosis. BACKGROUND: Differential diagnosis between TTR-related and AL amyloidosis is often complex and time-consuming. METHODS: Patients under routine observation with TTR-related/AL systemic amyloidosis and echocardiographic evidence of cardiac involvement were studied with 99mTc-DPD scintigraphy. RESULTS: Patients with cardiac involvement of TTR-related (group A; n = 15) and AL (group B; n = 10) etiology were comparable for left ventricular mass and renal function. Heart and heart/whole-body tracer retention were significantly higher (p < 0.05) in group A as compared with group B and with 10 unaffected controls. At visual scoring, cardiac 99mTc-DPD uptake was present in all group A patients and absent in all group B patients; thus, using genotyping/immunohistochemistry as the reference technique, the accuracy of 99mTc-DPD scintigraphy for distinction of TTR-related and AL etiology was 100%. Cardiac 99mTc-DPD uptake was also absent among unaffected controls. Using echocardiography as the reference standard for recognition of cardiac involvement, sensitivity and specificity of scintigraphy were both 100% for group A patients; in group B, sensitivity was 0% and specificity was 100% (accuracy, 50%). Eleven patients with myocardial 99mTc-DPD uptake underwent 99mTc-methylene diphosphonate (99mTc-MDP) scintigraphy; all patients showed a 99mTc-MDP myocardial visual score of 0. CONCLUSIONS: Etiology is a third major cause--in addition to type of organ-involved (soft-tissue/heart) and tracer type--of scintigraphic variability in cardiac amyloidosis. This is a highly relevant consideration for future studies. We conclude that 99mTc-DPD scintigraphy is a useful step in the workup of the differential diagnosis of TTR versus AL etiology in patients with documented cardiac amyloidosis.     

Comparison of technetium-99m sestamibi and thallium-201 retention characteristics in canine myocardium.

OBJECTIVES. The aim of this study was to compare the myocardial retention of technetium-99m (Tc-99m) sestamibi and thallium-201 over a wide range of blood flow at different time points after tracer injection. BACKGROUND. Technetium-99m sestamibi has been proposed as a new perfusion tracer with better physical characteristics than those of thallium-201 for scintigraphic imaging. However, no studies have simultaneously compared the ability of both tracers to assess myocardial blood flow during pharmacologic vasodilation. METHODS. The myocardial retention of Tc-99m sestamibi and thallium-201 were compared over a wide range of blood flow induced by regional coronary occlusion and dipyridamole infusion in an open chest dog model. Myocardial retention of both tracers was determined by in vitro tissue counting at 2, 5, and 20 min after tracer injection and was correlated with microsphere-determined blood flow. RESULTS: Thallium-201 demonstrated greater absolute tissue retention than did Tc-99m sestamibi. At 2 min after tracer injection, there was an almost linear relation between the retention of both tracers and myocardial blood flow over a wide flow range. However, this relation was not maintained over time. At 20 min after injection, the retention of both tracers underestimated myocardial blood flow at higher flow rates. At 2, 5 and 20 min after injection, increments of relative tracer retention between the different levels of flow were always greater for thallium-201 than for Tc-99m sestamibi. CONCLUSIONS. Thallium-201 displays more suitable physiologic characteristics as a flow tracer and may allow better differentiation of myocardial regions with different levels of coronary flow reserve. For both tracers, early cardiac imaging may minimize underestimation of blood flow at higher flow rates.     

Measurement of right ventricular volumes using 131I-MAA

A method has been presented for determining the right ventricular residual ratio, that is, the ratio of the end-systolic volume to the end-diastolic volume during each cardiac cycle. ¹³¹I-MAA was injected as a bolus into the right ventricle, and the ratio of isotope remaining in the chamber during the succeeding cardiac cycles was determined with a collimated scintillation counter placed over the right ventricle. Since the counter detected the radioactivity from the entire right ventricular cavity, potential errors from incomplete mixing were minimized. The washout curve from the ventricle was distorted somewhat by the accumulation of isotope in intervening lung tissue. This distortion was eliminated by subtracting the build-up curve of radioactivity in the lung recorded simultaneously with a second scintillation counter positioned over the lateral chest wall.In 14 dogs anesthetized with chloralose, the right ventricular residual ratio was relatively constant at 40.4 ± 3.1 per cent. Duplicate measurements differed by less than 3 per cent indicating the good reproducibility of the method.Right ventricular stroke volume was determined from cardiac output (dye dilution) and heart rate. With this and the simultaneously determined residual ratio (¹³¹I-MAA), end-diastolic volume could be calculated. Stroke volume and stroke work were highly correlated with end-diastolic volume, in keeping with the Frank-Starling mechanism.     

Hemodynamic and Renal Effects of Atrial Natriuretic Factor (99-126) in Volume Expanded Sheep

ABSTRACT

The renal and hemodynamic effects of atrial natriuretic factor 99-126 (ANF) were examined in hypervolemic sheep and the results compared to responses previously observed in normal isovolemic sheep. Infusion of 500ml dextran over 60 min increased blood pressure by 6 ± 2 mmHg, associated with increases in cardiac output and stroke volume. No change was seen in heart rate nor total peripheral resistance. Subsequent infusion of ANF at 100 μg/h for 60 min reduced blood pressure by 6 ± 1 mmHg and decreased stroke volume and cardiac output. There was no change in heart rate. Total peripheral resistance decreased slightly, to a similar degree to that seen after control infusion of 500 ml dextran. Moderate increases in urine volume, sodium and chloride excretion were seen after infusion of dextran and subsequent infusion of ANF markedly enhanced these renal effects. The renal changes produced by ANF in volume expanded sheep were significantly greater than those observed in normal sheep. Although normal sheep are more sensitive to the hemodynamic than to the renal effects of ANF, after dextran pretreatment there was enhancement of the renal responses with little change in the effects on blood pressure.     

Postural changes in cardiac volumes in men in relation to adult age

Cardiac volumes by equilibrium gated cardiac blood pool scans and heart rate were measured in the supine and sitting positions in 64 male volunteer subjects (age 25-80 yrs) who had been rigorously screened to exclude cardiovascular disease. After the upright position was assumed, the average cardiac output of all subjects was unchanged but heart rate increased and stroke volume decreased due to a decrease in end diastolic volume. Neither the supine or sitting cardiac output nor the average postural change in cardiac output, cardiac volumes or heart rate was age-related. While the average cardiac output among the subjects was unaltered with a change in posture, in some individuals it increased slightly while in others it decreased. The postural change in cardiac output among the individuals correlated by linear regression analysis with a change in heart rate only in younger subjects and with a change in stroke volume in all age groups, but the slope of this relationship was greater in older than in younger subjects. The postural change in stroke volume was strongly correlated with a change in end diastolic volume and this relationship did not vary with age. Thus, although the average postural change in cardiac output among healthy subjects is not age-related, a given change in cardiac output with posture in an older individual depends more on a change in stroke volume and less on a heart rate change than in a younger one. This result, like the response to vigorous upright exercise previously demonstrated to occur with aging, indicates a greater reliance in the elderly on the Frank-Starling mechanism than on heart rate for a given change in cardiac output in response to perturbations from the basal supine state.     

The evaluation of an isotopic clearance technique for the measurement of skin blood flow in the pig

An isotope, Technetium-99m (^99mTc), clearance technique has been used for measuring skin blood flow in the pig. The isotope is injected id, and the blood clearance of the tracer from the injection site is measured by scintillation detectors placed over the site of injection. The results showed that the ^99mTc-clearance technique in the pig was reproducible for comparable sites on opposite sides of the animal. When measurements were made along the midlateral flank skin a pattern of uniform blood flow was indicated. When the volume of tracer injected was varied (0.02–0.3 ml), no significant difference in the blood flow parameters measured was obtained. This result is compared with published findings in man and other animal systems. The clearance curves obtained over a period of 1 hr has two exponential exponents; the significance of this is discussed.     

Non-invasive measurement of renal blood flow with 99mTc DTPA: comparison with radiolabelled microspheres

This technique for non-invasive measurement of renal blood flow is based on the principle of fractionation of cardiac output, and applicable with any recirculating gamma activity tracer. It effectively determines the count rate that would be recorded over the kidney if the tracer behaved like radiolabelled microspheres and was completely trapped in the kidney on first pass. After correction for kidney depth, the estimated first pass activity plateau, expressed as a fraction of the injected dose, is equal to the kidney's fraction of cardiac output. The principle of the technique was validated by comparison with renal blood flow based on radiolabelled microspheres. Nine separate comparisons were made in two anaesthetised dogs. A known dose of 99mTc radiolabelled microspheres (particle size 23-45 microns) was injected into the left ventricle and the count rate over each kidney recorded. A known dose of 99mTc diethylenetriaminepenta acetic acid (DTPA) was then given as an intravenous bolus and the data recorded dynamically with a gamma camera online to a computer. After subtraction of the stable signal arising from the preceding radiolabelled microspheres, the theoretical first pass activity plateau from the DTPA that would have been recorded if the DTPA, after reaching the systemic circulation, had behaved like radiolabelled microspheres and become completely trapped in the renal vascular bed, was estimated. Using doses based on syringe counts before and after injection the ratio of renal blood flow values given by the two techniques (DTPA:RLMS) was 1.14 (SD 0.22) for the left kidney and 1.1(0.17) for the right. Using doses based on whole body counts, corresponding ratios were 1.05(0.11) and 1.02(0.13).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiac output determined by echocardiography in patients with cirrhosis: comparison with the indicator dilution technique

BACKGROUND/AIMS: Measurement of cardiac output in hyperkinetic patients with cirrhosis by Doppler echocardiography is increasingly reported, but has not been validated. We have compared simultaneous measurements of cardiac output by Doppler echocardiography (CO(d)) and by the indicator dilution technique (CO(I)). METHODS: Twelve patients with cirrhosis were studied. CO(d) was measured as the spatial mean velocity of the left ventricular outflow tract, multiplied by the cross-sectional area and the heart rate. CO(I) was determined by the standard indicator dilution technique after injection of 125I albumin and 99mTc albumin into the right atrium and subsequent sampling from the femoral artery. RESULTS: The mean CO(d) and CO(I) were similar (7.20 vs 7.15 l/min, NS). A highly significant correlation was present between CO(d) and CO(I) (r = 0.86, P < 0.0001; slope 0.91, Y(0) = 0.78 l/min). However, the mean squared difference between CO(d) and CO(I) was 2.3 (l/min)2. A Bland-Altman plot revealed no trend with the level of cardiac output. The standard deviation (0.79 vs 0.30 l/min, P < 0.01) and the coefficient of variation (10.5 vs 4.2%, P < 0.01) of duplicate measurements were significantly higher with the Doppler technique. CONCLUSION: Doppler measurements of cardiac output in groups of patients with cirrhosis are accurate with respect to the group mean, but marked disagreements of over- and underestimation were seen in individual patients. The reproducibility of the Doppler technique is acceptable, although not as good as that of the indicator dilution technique.     

Stability of cirrhotic systemic hemodynamics ensures sufficient splanchnic blood flow after living-donor liver transplantation in adult recipients with liver cirrhosis

AIM： To investigate the correlation between systemic hemodynamics and splanchnic circulation in recipients with cirrhosis undergoing living-donor liver transplantation （LDLT）, and to clarify how systemic hemodynamics impact on local graft circulation after LDLT.
METHODS： Systemic hemodynamics, indocyanine green （ICG） elimination rate （K,cG） and splanchnic circulation were simultaneously and non-invasively investigated by pulse dye densitometry （PDD） and ultrasound. Accurate estimators of optimal systemic hyperdynamics after LDLT [i.e., balance of cardiac output （CO） to blood volume （BV） and mean transit time （MTT）, defined as the time required for half the administered ICG to pass through an attached PDD sensor in the first circulation] were also measured. Thirty recipients with cirrhosis were divided into two groups based on clinical outcomes corresponding to postoperative graft function.
RESULTS： Cirrhotic systemic hyperdynamics characterized by high CO, expanded BV and low total peripheral resistance （TPR） were observed before LDLT. TPR reflecting cirrhotic vascular alterations was slowly restored after LDLT in both groups. Although no significant temporal differences in TPR were detected between the two groups, CO/BV and M＇IT differed significantly. Recipients with good outcomes showed persistent cirrhotic systemic hyperdynamics after LDLT, whereas recipients with poor outcomes presented with unstable cirrhotic systemic hyperdynamics and severely decreased KICG. Systemic hyperdynamic disorders after LDLT impacted on portal venous flow but not hepatic arterial flow.
CONCLUSION： We conclude that subtle systemic hyperdynamics disorders impact on splanchnic circulation, and that an imbalance between CO and BV decreases portal venous flow, which results in critical outcomes.     

Specific features of left ventricular hypertrophy in hypertensive obese women. An echocardiographic study

The echocardiographic features of the left ventricle of 37 obese women (body mass index above 30) and 37 lean controls, matched for sex, age, height and blood pressure levels, were studied. Twenty-six patients in each group were hypertensive. The normotensive obese patients did not show any differences, comparing to the normotensive controls; on the contrary, the hypertensive obese patients had higher left ventricular mass (LVM), stroke volume and cardiac output (CO), and lower total peripheral resistance (TPR) than the hypertensive controls. A positive correlation was found between the LVM and the CO (r = 0.57, P less than 0.01) in hypertensive obese patients, and between the relative wall thickenss (h/r, that is the ratio between the left ventricular wall thickness and the left ventricular radius) and TPR (r = 0.64, P less than 0.01) in the hypertensive controls. It is concluded that obesity per se does not determine left ventricular hypertrophy in women; however, when obesity is associated with arterial hypertension, a distinct pattern of hypertrophy, characterized by high CO and low TPR, develops.     

应用时间-空间相关成像技术评估妊娠期高血压疾病胎儿心功能

目的 探讨时间-空间相关成像(spatio-temporal image correlation,STIC)技术评价妊娠期高血压疾病胎儿心功能的临床应用。方法 运用STIC技术采集110例正常孕妇胎儿及84例妊娠期高血压疾病（PIH）孕妇胎儿心动周期图像,通过VOCAL功能获得容积参数,包括左、右心室舒张末期容积（LVEDV、RVEDV）,左、右心室收缩末期容积（LVESV、RVESV）,计算出左、右心室每搏量（LVSV、RVSV）,左、右心室射血分数（LVEF、RVEF）,左、右心室心排出量（LVCO、RVCO）。根据孕妇高血压严重程度及临床症状分为:PIH I组(孕妇血压轻度升高或轻度子痫前期):即孕妇妊娠20周后第1次出现血压升高,140/90 mmHg≤血压值<160/110 mmHg(1 mmHg=0.133 kPa),间隔6 h以上,至少出现过两次,尿蛋白弱阳性;PIH II组(重度子痫前期):血压≥160/110 mmHg,和(或)尿蛋白阳性或者强阳性(++),或伴有微血管溶血、神经系统及肺水肿等症状。结果 ①与对照组相比,PIH I组胎儿左、右EDV、ESV、SV、EF、CO差异均无统计学意义;②与对照组、PIH I组相比,PIH II组胎儿的左、右EDV、ESV增大、差异有统计学意义（P<0.05,P<0.01）,PIH II组胎儿的SV、EF、CO均减小,差异有统计学意义（P<0.05,P<0.01）。结论 STIC技术可以评价妊娠期高血压病胎儿心功能的变化。     

An improved noninvasive method for measurement of cardiac output and evaluation of left-sided cardiac valve incompetence

A time-saving method was developed to label red blood cells in vitro with 99mTc while avoiding centrifugation. After tin incubation, extracellular tin was oxidized by sodium hypochlorite, and EDTA was added for stabilizing the complex prior to 99mTc incubation. Labeling yields were 95%, and in vivo decay showed a high stability with a mean biologic half-life of eleven hours. The first-passage radionuclide technique for determination of cardiac output using the above-mentioned tracer was evaluated by using the left ventricle as area-of-interest with individual background correction after complete mixing of the tracer. This technique showed a high level of agreement with invasive methods. By combining this method for measurement of the forward stroke volume with the multigated equilibrium principle for determination of the total left ventricular stroke volume using similar background corrections, an exact evaluation of regurgitation fractions was obtained. In patients with aortic and mitral valve disease the noninvasive radionuclide technique gave similar but probably more accurate results as compared with contrast aortography and ventriculography. The radionuclide technique may be suitable for monitoring and selecting patients for surgical treatment.     

Effects of diltiazem and long-term beta 1-adrenergic blockade on hemodynamics and blood flow during exercise in patients with stable angina pectoris

The short-term effects of oral diltiazem on hemodynamics and distribution of cardiac output at rest and during semiupright bicycle exercise were evaluated in eight patients with stable effort angina on long-term beta 1-adrenergic blockade. Cardiac output and iliofemoral blood flow were measured using thermodilution. The patients were exercised to the same work load on a bicycle before and 2 h after oral diltiazem (60 mg in two patients and 120 mg in six). At maximal exercise, diltiazem reduced heart rate from 94 +/- 5 to 88 +/- 6 beats/min (p less than 0.01), mean arterial pressure from 139 +/- 5 to 127 +/- 4 mm Hg (p less than 0.01) and systemic vascular resistance from 9.7 +/- 0.7 to 8.4 +/- 0.4 x 10(2) dynes.s.cm-5 (p less than 0.05) compared with control. During exercise, cardiac output, iliofemoral blood flow, mean pulmonary wedge pressure and mean right atrial pressure were not altered, but stroke volume increased from 119 +/- 11 to 131 +/- 10 ml (p less than 0.05). Maximal ST segment depression during exercise was decreased and angina was less. Diltiazem does not alter the distribution of the cardiac output during exercise but improves ischemia.     

Cardiac index in ambulatory patients estimated by precordial dilution curves

1. 1. Four hundred and twenty-nine radiocardiograms were obtained in 240 ambulatory patients with and without heart disease by means of wide angle external counting over the precordium after the injection of radioactive iodinated human serum albumin into an antecubital vein. Cardiac index was calculated from the radiocardiogram and the blood volume. Only seven patients were encountered in whom a tracing adequate for calculation of cardiac index was not obtained.

2. 2. A mean cardiac index of 3.51 L. per minute per square meter surface area with a standard deviation of 0.97 was derived from forty-eight persons without known cardiac or vascular disease. Cardiac indices were slightly but significantly lower when derived from radiocardiograms taken twenty minutes after the initial tests. By contrast, cardiac indices did not differ significantly when calculated from tracings made weeks to months apart in patients with stable cardiovascular systems.

3. 3. A significant decrease in cardiac index was observed in patients with all types of heart disease who had congestive heart failure, whether overt or controlled.

4. 4. In the absence of congestive heart failure, mean cardiac index was increased in patients with borderline hypertension, normal in those with systolic hypertension, and frequently reduced in those with sustained diastolic hypertension, especially when evidence of myocardial involvement also was present.

5. 5. Cardiac index was usually normal in patients with coronary artery disease in the absence of congestive heart failure. Occasional reduction was seen in patients with old myocardial infarctions.

6. 6. A probably significant decrease of cardiac index as measured by the external counting technic was observed in patients with valvular heart disease without congestive heart failure. Also, cardiac index in congestive heart failure due to valvular heart disease was lower than that due to other types of heart disease. Valvular insufficiency apparently leads to erroneously low values of cardiac index estimated by the external counting technic.

7. 7. Classification of radiocardiograms according to qualitative features showed some correlation with cardiovascular status. Prominent fluctuations on the downslope were recognized most often in radiocardiograms of patients with valvular insufficiency. The appearance of the radiocardiogram maintained a constancy over considerable periods of time in the absence of marked change in cardiovascular status.

     

Intravascular volume in cirrhosis

Previous studies of blood volume (BV) in cirrhosis have either not adjusted BV properly for body size; determined plasma volume from the dilution of labeled albumin 10-20 min postinjection, when some extravascular redistribution has already occurred; and/or not used the correct whole body-peripheral hematocrit ratio (0.82) in calculating whole BV from plasma volume and the peripheral hematocrit. We measured BV with attention to these considerations in 19 patients with cirrhosis and reexamined the determinants of vascular volume and the relationship between vascular volume and sodium retention. BV was calculated as plasma volume (determined from extrapolated plasma activity of intravenously injected [131I]+albumin at time 0) divided by (peripheral hematocrit X 0.82). The result was expressed per kilogram "dry" body weight, determined by subtracting the mass of ascites (measured by isotope dilution; 1 liter = 1 kg) from the actual body weight of nonedematous patients. Measured and expressed in this way, BV correlated strongly with esophageal variceal size (r = 0.87, P less than 0.05), although not with net portal, right atrial, inferior vena caval, or arterial pressure, and was significantly greater in patients with sodium retention as compared to patients without sodium retention. The principal modifier of vascular volume in cirrhosis is vascular capacity, which is probably mainly determined by the extent of the portasystemic collateral circulation. Increased vascular volume in patients with sodium retention as compared to patients without sodium retention supports the "overflow" theory of ascites formation.     

Determination of cardiac output by single gated pulsed Doppler echocardiography

The aim of the study was to evaluate the use of single gated pulsed Doppler cross-sectional echocardiography for measurement of the cardiac output. Pulsed Doppler echocardiography was used to assess both area and blood velocity at the aortic orifice. Stroke volume estimates were determined by multiplying area by systolic time velocity integral as measured from the parasternal and apical approach, respectively. We investigated a group of 17 healthy individuals and a group of 20 patients with coronary artery disease. In the first group no change was found in aortic area during systole (P less than 0.01). During a follow-up of two weeks no change in aortic area was observed either (P less than 0.01). Intraobserver, interobserver and day-to-day variability of the aortic area, expressed as the coefficient of variation was 3.6 +- 5.2%, 4.6 +- 5.7% and 7.8 +- 3.8% (mean +- 1 SD), respectively. The interobserver variability of the time velocity integrals was 6.0 +- 6.2%. In the second group the cardiac output as measured with the thermodilution method ranged from 3.8 to 8.0 l/min. Comparison of the Doppler and thermodilution technique for measurement of cardiac output showed a correlation coefficient of r = 0.76 (P less than 0.001) and the following regression equation: CO (Doppler) = 1.0 x CO (thermodilution)-700 ml. The Doppler method underestimated cardiac output relative to the thermodilution method.     

Ascending aortic blood velocity and acceleration using Doppler ultrasound in the assessment of left ventricular function

We have used a 2.2 MHz continuous-wave Doppler blood velocity meter (Bach-Simpson BVM 202) to measure ascending aortic blood velocity and acceleration, and have obtained from the velocity signal a noninvasive measure of stroke volume and cardiac output by combining the Doppler technique with M-mode echocardiography. In two separate studies we have systematically altered the loading conditions of the heart with lower body pressure; and the inotropic state of the heart with dobutamine (5 micrograms . kg-1 . min-1), and documented the changes in mean velocity (MV), maximum acceleration (MA), stroke volume (SV), cardiac output (CO) and left ventricular end-diastolic dimension (EDD) (M-mode echocardiography). Application of lower body pressure to subjects in a 30 degrees head-up tilt position caused a systematic increase in preload, as shown by a 9% increase in EDD, which raised SV by a maximum of 33% (p less than or equal to 0.001) and CO by 32% (p less than or equal to 0.01), thus showing a classical Starling response; whilst there was relatively little increase in MA. Conversely, infusion of dobutamine, an inotropic agent, caused a 29.2% increase in MA (p less than or equal to 0.01) with minimal increase in SV. Thus, the ability to measure ascending aortic blood velocity allows noninvasive monitoring of changes in both inotropic state and Starling function, with considerable ease and rapidity.     

99mTc-pertechnetate uptake measurement in the rabbit knee-joint

We studied 99mTc- pertechnetate (TcO4) uptake measurements in rabbit knee joints. Results in non-inflamed rabbit knee joints indicated that the difference between paired measurements of both knees (R-L difference) was an accurate measure, independent of age and weight. In the early phase of unilateral antigen-induced arthritis, there was a particularly close correlation between R-L difference values and clinical scores of inflammation, reflecting an acute type of inflammation. Data obtained after the early phase of arthritis suggested that R-L difference measurements provide a more sensitive measure of inflammation than clinical scores. 99mTcO4 uptake measurements can reliably be used to detect and quantitate joint inflammation in animals as small as rabbits.     

后肢远程预处理对心肌缺血再灌注与心交感神经损伤的影响

目的：后肢远程缺血预处理对急性心肌缺血再灌注与心交感神经损伤影响的实验研究。方法：20只雄性新西兰大白兔随机被均分成两组：对照组及远程缺血预处理（RIPC）组。两组均制作心肌缺血模型。RIPC组在心肌缺血前行双后肢短暂缺血预处理2次（充气式压力止血带环扎双后肢腘窝上1／3,压力26．6kPa,每次10min,间隔10min）,最后一次后肢缺血预处理后再灌注60min制作急性心肌缺血模型。其方法为：冠状动脉左前降支完全闭塞45min,于松开结扎圈再灌注2、4h时,分别以碘-间位碘代苄胍（^131-MIBG）、^99m锝-甲氧基异丁基异腈（^99mTc-MIBI）双核素作放射自显影,其后以美蓝、氯化四唑（TTC）作组织染色,分别确定心肌危险梗塞灶与实际梗塞灶。结果：再灌注4h后,预处理组危险梗塞灶与实际梗塞灶均小于对照组（P〈0．01）。^131I-MIBG及^99m～Tc-M1BI自显影在同一区域摄取存在差异性,两组^131I-MIBG显影缺损面积（40．8土3．2）％．均显著比^99mTc-MIBI显影缺损及实际梗塞灶大（P〈0．05）。结论：远程预处理能有效阻断心肌缺血再灌注对交感神经损伤的作用;利用交感神经显影剂MIBG显影能客观监测心肌梗塞病变范围和程度,评价远程预处理的心肌保护效应。