Comparison of bolus and infusion methods for estimating hepatic blood flow in patients with liver disease using indocyanine green

A non-invasive method of estimating liver blood flow by a two-compartment pharmacokinetic model of the plasma clearance of indocyanine green has been previously described in normal animals and patients without liver disease. This non-invasive technique has been compared with the conventional method of measuring liver blood flow by hepatic vein catheterisation in 25 patients with liver disease. There was good correlation between the values for indocyanine green clearance, with the infusion method tending to produce slightly higher results. However, there was poor agreement in the measurement of liver blood flow, as the non-invasive technique over-estimated the hepatic extraction ratio and thus underestimated liver blood flow. Therefore, in patients with liver disease the non-invasive method cannot be relied upon or replace hepatic vein catheterisation for the measurement of liver blood flow.     

Methodological problems in the use of indocyanine green to estimate hepatic blood flow and ICG clearance in man

Liver blood flow (Q) is often measured by constant infusion of ICG (i), concentration measurements in an artery (A) and a hepatic vein (V): Q = (A-V)/A. Some authors use ICG clearance, Cl = i/A, as a measure of Q assuming complete hepatic extraction. During the infusion, the ICG concentration often increases. The importance of this for calculated values of Q and Cl was examined, and the use of Cl as a measure of Q was reevaluated. ICG was given as 0.06-0.20 mumol/min to 52 subjects with liver disease, and about 0.20 mumol/min to 86 subjects with no liver disease. ICG concentration increased steeply during the first 90 min after start of the infusion; thereafter the increment was constant as evaluated in successive 40-min periods in eleven 320-min studies (analysis of variance P greater than 0.5); on average, 6 +/- 1% per hour (+/- SD). Q was not time-dependent (P greater than 0.5). ICG clearance decreased significantly, on average 5 +/- 2% per hour (+/- SD). Hepatic extraction fraction, (A-V)/A, (measurement period 90-130 min) was 0.34 +/- 0.21 in liver patients (+/- SD) and 0.61 +/- 0.80 in controls. Cl and Q were positively correlated in both groups but with substantial scatter. Thus, not only is the calculated ICG clearance time-dependent but the extraction fraction is further so low and variable, that any use of ICG clearance as a measure of liver flow is not justified.     

Clinical value of the study of myocardial blood flow by the method of Xe133 clearance in ischemic heart disease]

The clearance of intracoronarily introduced 133Xe was employed in investigating the myocardial blood flow in 105 patients, 10 of whom--controls and 95 suffering from various manifestations of ischemic heart disease. Use was made of the biexponential calculation of the clearance curve by taking account of the fast (circulation in normal tissues) and slow exponent (circulation along the cicatricially-altered sections of the myocardium) contributions to the common "effective" myocardial blood flow. In patients with ischemic heart disease a reduction of the myocardial blood flow depending upon the severity of the clinical picture and the degree of the coronary arteries lesion was revealed. A direct correlational dependence between the initial state of the myocardial circulation at rest and the level of the physical efforts tolerance was educed. A conclusion is drawn that the determination of the myocardial circulation by the method of the 133Xe clearance following intracoronarily administration of the substance should be done by taking account of the slow and fast exponents of the clearance curve, these exponents reflecting the circulation in sections of the myocardium differing in their functional activity.     

肝硬化患者红细胞参数测定及临床意义

目的 观察肝硬化患者红细胞参数变化,探讨其临床意义.方法 检测45例肝硬化患者(肝硬化组)红细胞计数(RBC)、血红蛋白含量(Hb)、红细胞比积(HCT)、平均红细胞体积(MCV)、红细胞体积分布宽度(RDW),并与42例健康者(对照组)进行比较.结果 与对照组比较,肝硬化组的RBC、HCT、Hb均显著下降(P<0.05),MCV、RDW显著升高(P<0.05,P<0.01),并且随着Child-Pugh积分的增加,红细胞参数的异常程度逐渐加重(P<0.05,P<0.01).结论 肝硬化患者存在红细胞异常,红细胞参数可以反映肝病的肝损程度和病情轻重.     

Comparative study of hydrogen and aminopyrine clearance methods for determination of gastric mucosal blood flow in dogs

Effects of pentagastrin, histamine, PGI₂, and vasopressin on gastric mucosal blood flow (GMBF) in innervated stomachs of anesthetized dogs were measured by means of the hydrogen clearance method, using a contact electrode. The results were compared with findings obtained with the aminopyrine (AP) clearance method in Heidenhain pouch preparations. Pentagastrin at 2 and 8 g/kg/hr had no effects on GMBF, as measured by the hydrogen clearance method, but there was a marked increase in GMBF when the AP clearance method was used. Histamine at 40 or 160 g/kg/hr tended to reduce or significantly reduced GMBF when measured with the hydrogen clearance method, but there was a significant increase in GMBF with the AP clearance method. Both PGI₂ (3 or 30 g/kg/hr) and vasopressin (0.06 or 0.25 units/kg/hr) reduced GMBF as determined by both methods. These results indicate that the hydrogen clearance method is advantageous for detecting regional GMBF but is disadvantageous when attempting to detect the effects of agents which increase GMBF.The Editor wishes to express publicly his regrets to the authors that the editorial planned to highlight this paper will not appear until next month. He particularly apologizes for the long delay in publishing after the paper had been accepted in anticipation of the editorial to appear in the same issue.     

The determinants of systolic pulmonary venous flow reversal by transthoracic pulsed Doppler in mitral regurgitation: its value in determining the severity of regurgitation

OBJECTIVE: Systolic pulmonary venous flow reversal (SPVFR) has been evaluated in mitral regurgitation (MR) primarily by transoesophageal echocardiography (TEE). There is limited study on the value of SPVFR obtained from transthoracic echocardiography (TTE) for the quantification of MR. In this study, determinants of SPVFR and the accuracy of SPVFR obtained with TTE in determining the severity of MR were investigated. METHODS AND RESULTS: Fifty patients with MR in whom reference quantitative Doppler evaluation was carried out formed the study group. Thirty-nine of them underwent cardiac catheterization. In all patients, SPVFR was evaluated by pulsed Doppler echo placed both at the right and left pulmonary vein in the apical four-chamber view. The SPVFR was present in 26 (52%) patients. Atrial fibrillation, and grade III-IV MR by catheterization were more frequent in patients who had SPVFR. Patients with SPVFR had increased values for regurgitant orifice area, regurgitant volume, regurgitant fraction, and left atrium/left ventricle diameters and volumes compared to patients without SPVFR. After multivariate analysis regurgitant fraction (RF) was the single and most powerful determinant of SPVFR (p<0.001). The SPVFR had high sensitivity, specificity and accuracy for the diagnosis of severe MR (89, 95 and 92%, respectively). CONCLUSION: It was concluded that SPVFR is a useful method for the evaluation of the severity of mitral regurgitation.     

Beneficial effect of physical training on blood flow to myocardium perfused by chronic collaterals in the exercising dog

To determine the effect of physical training on collateral blood flow, we measured regional myocardial blood flow (MBF) by injecting 15 mu radioactive microspheres at rest and during exercise in 14 dogs with chronic coronary occlusive lesions. Seven dogs subsequently trained for 6 weeks while the other seven remained in kennels. Training effect was documented by decrease in heart rate during exercise that averaged 35 beats/min. MBF studies were repeated after 6 weeks. Myocardial samples were obtained from normally perfused zones (NZ) and from regions supplied via collaterals (collateral dependent zones or CZ). Initially, endocardial blood flow in CZ averaged 1.110 ml/min/g (83% of NZ, P less than 0.05) at rest and 1.36 ml/min/g (69% of NZ, P less than 0.05) during exercise, indicating relative underperfusion. Epicardial blood flow was equal in NZ and CZ. After 6 weeks MBF was not significantly changed in control animals. After training, however, MBF to underperfused endocardium of CZ during exercise was 39% greater than it had been prior to training. The epicardial portion of CZ (not exhibiting underperfusion) showed no change in MBF during exercise after training. Our data suggest that beneficial effects of training in coronary disease may include improvement in MBF to underperfused collateral-dependent portions of myocardium.     

Changes in blood flow of growing experimental tumor determined by the clearance of 133Xe

133Xe clearance method has been employed for measurement of the blood flow in 6C3HED lymphosarcoma implanted in flank of C3H mice. In small tumors (9-day old) the mean rate of blood flow was 9.4 +/- 5.0 ml/100g/min. but with progressing growth of tumors the rate of blood flow significantly decreased. In large tumors (14-day old) the mean rate of the blood flow was only 5.4 +/- 2.8. Our results demonstrate that this type of tumor, similarly as most of transplanted tumors are not well perfused and, that there is an inverse relationhip between the blood flow and the tumor size.     

Assessment of hepatic steatosis and hepatic tissue blood flow by xenon computed tomography in nonalcoholic steatohepatitis

Aim:  The diagnosis of non-alcoholic steatohepatitis (NASH) can be difficult using blood tests and imaging studies. Histological diagnosis by liver biopsy remains the gold standard of NASH diagnosis. There is an urgent need to develop and validate simple, reproducible, noninvasive tests to accurately assess NASH stage and grade. We assess the usefulness of xenon computed tomography (Xe-CT), as a non-invasive method of quantitatively and visually determining hepatic tissue blood flows (TBFs), and xenon solubility (λ value) simultaneously with TBF, in the evaluation of NASH pathophysiology.
Methods:  Histological severity of fatty changes and severity of fibrosis based on Brunt's classification were determined in 38 NASH patients. We evaluated correlations between the grade of fatty changes and λ value, and correlations between the stage of fibrosis and TBFs.
Results:  The λ value showed significant positive correlations with both grade of steatosis ( r  = 0.813, P  < 0.001) and each 10% range of histological fatty infiltration ( r  = 0.926, P  < 0.001). A significant negative correlation was seen between λ value and the liver : spleen ratio ( r  = −0.835, P  < 0.001). Portal venous tissue blood flow and total hepatic tissue blood flow showed significant negative correlations with the progression of fibrosis ( r  = −0.465, P  < 0.01; r  = −0.433, P  < 0.01, respectively). Total hepatic tissue blood flow tended to decrease with progressing grade of steatosis.
Conclusion:  Xe-CT offers a convenient and objective method for evaluating fatty infiltration and changes in blood flow in the entire liver, and appears useful for detailed evaluation of patients with NASH.