Effect of high flow arteriovenous fistula on cardiac function in hemodialysis patients

Background

Vascular access for hemodialysis (HD) with an inappropriately high flow may underlie the onset of high output heart failure (HOHF).The aim of this study was to determine the prevalence of high flow access (HFA) in chronic HD patients, and to determine its effects on cardiac functions.

Effect of Increased Blood Flow Rate on Hemodialysis Tolerability and Achieved Urea Reduction Ratio

Long‐term hemodialysis (HD) imposes a significant burden on the quality of life of end‐stage kidney disease patients. Optimizing dialysis dose is an important consideration in this population; however, evidence exists that suggests that attainment of population dialysis targets is associated with increased intradialytic complications. In this prospective, before‐after study, the blood flow rate (BFR) of 63 maintenance HD patients was increased by 100 mL/min to a maximum BFR of 400 mL/min to determine the impact on patient tolerability and urea reduction ratio (URR) of an increased BFR. Tolerability was assessed by time to recovery (TTR) after dialysis, a validated measure of patient tolerability, and intradialytic complications. Median pre‐increase BFR was 252 mL/min compared to 349 mL/min post‐increase. Mean TTR decreased from 4.67 h to 4.03 h (P = 0.688). No association was observed between percentage change in BFR (R2 = 0.0) or post‐increase BFR (R2 = 0.0) and absolute change in TTR. A significant, positive association was observed between both the absolute and relative changes to BFR and the achieved URR. We found no evidence that increasing BFR by 100 mL/min diminishes patient tolerability.     

Establishment of a Blood Purification System for Renal Failure Rats Using Small‐Size Dialyzer Membranes

Hemodialysis techniques for small animals have not been established because no small dialysis apparatus has been available. We recently developed a small‐size dialyzer and established an appropriate blood purification system for small animals. To confirm the appropriate dialysate flow rate, bovine blood was dialyzed for 60 min at a fixed blood flow rate of 1.0 mL/min and variable dialysate flow rates. Blood urea nitrogen and creatinine levels decreased significantly at a dialysate flow rate of 5 mL/min (from 13.7 ± 0.2 to 10.3 ± 1.2 mg/dL and 1.07 ± 0.15 to 0.61 ± 0.12 mg/dL, respectively, P < 0.05). To determine the appropriate in vivo conditions, extracorporeal circulation was performed in anesthetized male Sprague‐Dawley rats at a dialysate flow rate of 0.0 mL/min, for 240 min, and at variable blood flow rates. Extracorporeal circulation was successful at a blood flow rate of 1.0 mL/min, but not 1.5 mL/min. To establish in vivo hemodialysis conditions, we used the animal model of end stage renal failure. Sprague‐Dawley rats were fed a 0.75% adenine‐containing diet for 3 weeks, after which they received hemodialysis for 120 min at a dialysate and blood flow rate of 5.0 and 1.0 mL/min, respectively. There were no significant changes in systolic blood pressure or heart rate during dialysis. Thus, this blood purification system can be safely used for small animals at a dialysate flow rate of 5.0 mL/min and a blood flow rate of 1.0 mL/min. This system provides a basis for further research on hemodialysis therapy.     

Association of Preoperative Mean Arterial Pressure With the Primary Failure of Brescia‐Cimino Arteriovenous Fistula Within the First 7 Days Following Surgery in Hemodialysis Patients

This retrospective study included 1051 patients with end‐stage kidney disease and Brescia‐Cimino arteriovenous fistula (AVF) (excluding pre‐dialysis patients), and aimed to investigate the role of blood pressure in AVF primary failure. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured twice daily for 3 days before surgery. The success (N = 1010) and failure (N = 41) groups were based on AVF primary failure within 7 days of surgery. The cephalic vein was larger and the preoperative mean arterial pressure (MAP) was higher in the success group compared with the failure group (P < 0.05). Cephalic vein diameter and preoperative MAP independently predicted AVF primary failure within 7 days after surgery. In conclusion, small cephalic vein diameter and low preoperative MAP were associated with AVF primary failure within 7 days of surgery.     

Expansion of Blood Volume Increases the Primary Patency Rate of Arteriovenous Fistulas for Hemodialysis in Patients With Critical Arterial Quality

The aim of our prospective study was to find out if the expansion of blood volume can improve early arteriovenous fistula (AVF) function after construction in patients with marginal vessel quality. Before AVF construction, the arteries of the upper arm were examined by duplex sonography. Patients with critical values of internal artery diameter (IDA) <1.6 mm, resistance index (RI) at reactive hyperemia (RH) >0.7 and feeding artery blood flow (ABF) <24 mL/min were divided into two groups by random sampling. One group received plasma expander (hydroxyethyl starch) during surgery and the other did not. During the surgical procedures to construct 43 AVFs in 37 patients with critical artery quality, the patients received a mean volume of 720 mL (range 320–1000 mL) of plasma expander. The primary patency rate in this group was 86% (37/43). In the other group of 37 patients with critical artery quality, 42 AVFs were constructed and no plasma expander was given during surgery. The primary patency rate was 26.2% (11/42, P > 0.001). The two‐year survival of the AVF in the group given plasma expander was 66.3%, and in the other group it was 13.3%. In our study, the infusion of plasma expander in patients with critical artery quality increased the primary patency rate after AVF construction. Based on the morphological and functional characteristics of arteries determined by pre‐operative duplex sonography, the need for blood volume expansion could be predicted.     

透析液流量对血液透析充分性的影响

目的：观察增加透析液流量（Qd）对维持性血液透析（MHD）患者透析充分性的影响。方法：随机选择稳定透析6个月以上的MHD患者38例。血透透析液流量定于500ml／min和800ml／min各透析4周，其他透析参数[透析时间，血流量（Qb），超滤量和透析器型号与面积]不变。每种Qd量于第3周和第4周分别测定透析前后血尿素氮（BUN）、血肌酐（SCr）水平，记录每次透析的透析时间、超滤量及透析后体重（W），并根据Kt／V的自然对数公式计算Kt／V、尿素下降率（URR），取2次测定值的平均值作为患者该透析液流量的Kt／V。同时检测第4周及第8周透析前的血红蛋白（Hb）和红细胞压积（Hct）水平。采用成对t检验和卡方检验进行统计学分析。结果：本研究中每例患者构成自身对照，研究前后一般情况完全一致。Qd为800ml／min时URR及Kt／V值均较Qd流量为500ml／min时增加，具有统计学意义（P〈0．05），而SCr下降率、Hb和Hct水平略有增加趋势，无显著性差异。Qd为800ml／min时透析后URR〉65％的百分数明显高于Qd为500ml／min时，具有显著统计学意义（P〈0．001）。结论：将Qd从500ml／min增加至800ml／min，可显著增加URR、增加Kt／V，提高透析充分性达标率。800ml／min透析液流量的MHD可选择性用于不便于延长治疗时间和提高血流量达到透析充分性的患者。     

Comparison of Arterial and Venous Blood Flow Between Patients with Pressure Dressing or a New Hemostatic Puncture Closure Device After Cardiac Catheterization

The aim of the study was to compare arterial and venous flow volume in the punctured leg in patients given a conventional pressure dressing and those given a new hemostatic puncture closure device (Angio-Seal) after cardiac catheterization. We prospectively measured blood flow in 25 patients with pressure dressing (group A) and 25 patients with Angio-Seal (group B) after cardiac catheterization. Duplex sonographic measurements were performed at the superficial femoral artery and vein of the punctured leg. In group A measurements were performed before catheterization, during pressure dressing, and after removal of pressure dressing. In group B we performed the measurements before catheterization and after closure of the puncture site with Angio-Seal. Mean arterial and venous blood flow of the superficial femoral artery and vein were calculated. Statistical evaluation was performed using the one-sample Wilcoxon test. In group A there was a significant reduction of blood flow volume in both the femoral artery, from a mean of 119 mL/min before puncture to 78 mL/min with pressure dressing, and the femoral vein, from 114 mL/min before puncture to 82 mL/min with pressure dressing (P < 0.0001). After removal of pressure dressing the blood flow rose to 119 mL/min in the femoral artery and 116 mL/min in the femoral vein. In group B there was no change in flow volume before and after catheterization (femoral artery: 117 vs 118 mL/min, femoral vein 119 vs 120 mL/min, P = ns). We conclude that the use of pressure dressing after cardiac catheterization caused a significant reduction in arterial and venous blood flow (about 30%) during immobilization. The new Angio-Seal closure device did not affect arterial or venous flow.     

Relationship Between Short‐Term Blood Pressure Variability and Subclinical Renal Damage in Essential Hypertensive Patients

The authors aimed to analyze the relationship between subclinical renal damage, defined as the presence of microalbuminuria or an estimated glomerular filtration rate (eGFR) between 30 mL/min/1.73 m² and 60 mL/min/1.73 m² and short‐term blood pressure (BP) variability, assessed as average real variability (ARV), weighted standard deviation (SD) of 24‐hour BP, and SD of daytime and nighttime BP. A total of 328 hypertensive patients underwent 24‐hour ambulatory BP monitoring, 24‐hour albumin excretion rate determination, and eGFR calculation using the Chronic Kidney Disease Epidemiology Collaboration equation. ARV of 24‐hour systolic BP (SBP) was significantly higher in patients with subclinical renal damage (P=.001). This association held (P=.04) after adjustment for potential confounders. In patients with microalbuminuria, ARV of 24‐hour SBP, weighted SD of 24‐hour SBP, and SD of daytime SBP were also independently and inversely related to eGFR. These results seem to suggest that in essential hypertension, short‐term BP variability is independently associated with early renal abnormalities.     

Relation between Access Blood Flow and Mortality in Chronic Hemodialysis Patients

Background: Access blood flow (Qa) measurement is a potentially important determinant of systemic hemodynamics in hemodialysis patients. High Qa may contribute to left ventricular dilation and high output heart failure. On the other hand, low Qa might lead to underdialysis, which is associated with adverse outcomes.Methods: In this retrospective study of incident chronic hemodialysis patients treated in three Canadian cities (Edmonton, Calgary, and Halifax), the hypothesis that extremes of Qa(low or high) would be associated with increased mortality was tested. The distribution of Qa was not Gaussian, and therefore Qa was log-transformed in analyses that treated it as a continuous variable. Qa was classified into categories defined by cutpoints of 500, 1000, 1500, and 2000 ml/min. Univariate and multivariate Cox proportional hazard models were performed to examine the relation between Qa and all-cause mortality. Patients were followed from the date of Qa measurement until death; follow-up was discontinued at loss to follow-up, kidney transplantation, or end of study.Results: Of 820 participants, those with lower levels of Qa tended to be older and to have more comorbidities. During the median follow-up period of 28 mo, 206 (25.1%) participants died and 101 (12.3%) patients received a kidney transplant. When only baseline measures of Qa were considered, there was significant association between Qa and mortality [hazard ratio (HR) per unit increase in logQa 0.81, 95% confidence interval (CI) 0.67, 0.97; adjusted HR per unit increase in logQa 0.90, 95% CI 0.72, 1.11]. The adjusted risk of mortality was similar between the different categories of baseline Qa before and after adjustment for demographic characteristics, comorbidity, and access type. In analyses that included all Qa measurements per patient as a time-varying covariate, the adjusted association between Qa and death remained nonsignificant, with no evidence of increased mortality at higher Qa (HR per unit increase in logQa 0.82, 95% CI 0.67, 1.01, P = 0.066).Conclusion: The findings of this study do not suggest an increased risk of death at higher levels of Qa, Further studies would be needed to confirm an increased risk of death at lower Qa.Measurement of access blood flow (Qa) as a means to detect access dysfunction has become common over the past decade. Many dialysis programs now screen arteriovenous fistula and synthetic grafts on a repetitive basis, because observational studies have shown that low or declining Qa predict subsequent access failure (1–4). Qa is potentially affected by many factors, including systemic hemodynamics (i.e. BP and cardiac output), the size and endothelial function of the vessels supplying and draining the access, and the presence of significant vascular stenosis. Therefore Qa might theoretically serve as a marker of cardiovascular health in dialysis patients (5–8) If true, this suggests that Qa could be used to predict clinical outcomes in dialysis patients.However, any association between Qa and survival might not be straightforward. For instance, although low Qa might be linked to adverse outcomes through poor cardiac status or (in extreme cases) underdialysis (9), high Qa could also be problematic because it may contribute to left ventricular dilation and high output heart failure (10–17) This is supported by the observation that banding of high-flow arteriovenous fistulae apparently reverses heart failure and its associated hemodynamic changes (18–22). Because extremely high levels of Qa might therefore contribute to cardiovascular decompensation, regular echocardiography has been recommended for such patients (15).Thus, although both low and high Qa might lead to adverse outcomes, no data exist to confirm this. We hypothesized that extremes of Qa (low or high) would be associated with increased mortality in hemodialysis patients.     

Long beneficial effects after lipo‐prostaglandin E1 administration on the ischemic gastric tube in pigs

Lipo‐prostaglandin E1 (PGE1) is a new preparation of PGE1 in which it is bound to lipids in order to slow PGE1 release and delay its rate of metabolism. We investigated how long the beneficial effects of intravenous administration of lipo‐PGE1 on the ischemic gastric tube continue. The gastric tube was constructed using 15 domestic pigs under general anesthesia and saline, unmodified PGE1 and lipo‐PGE1 were infused continuously at a rate of 0.05 µg/kg/min for 10 minutes. Tissue blood flow (TBF) was analyzed from before administration to 120 minutes after the end of administration. There were no obvious changes in TBF during the administration of saline. However, TBF during treatment with unmodified PGE1 and lipo‐PGE1 was significantly increased to 13.1 ± 1.3 and 13.5 ± 1.4 mL/min/100 g, respectively (paired t‐test; P < 0.01). Although TBF was significantly decreased to 8.0 ± 1.0 mL/min/100 g on 10 minutes after the end of unmodified PGE1 administration (paired t‐test; P < 0.01), it was maintained over 10 mL/min/100 g until 120 minutes in lipo‐PGE1 group. Lipo‐PGE1 infusion leads to the objectively measurable improvement and the prolonged action in the blood perfusion of the gastric tube in pigs.     

Stent Placement Versus Angioplasty Improves Patency of Arteriovenous Grafts and Blood Flow of Arteriovenous Fistulae

Background: While endovascular stent placement is the standard of care in most percutaneous coronary and peripheral artery intervention, its role in the salvage of thrombosed and stenotic hemodialysis access remains controversial.Design, Setting, Participants, and Measurements: We compared the effects of stent versus angioplasty on primary patency rates in the treatment of stenotic arteriovenous fistulae (AVF) and arteriovenous grafts (AVGs). Moreover, we compared access flow (Qa) and urea reduction ratio (URR) between the two groups as a metric of the effect of stent placement versus angioplasty on dialysis delivery.Results: Cox regression analysis revealed that the primary assisted AVG patency was significantly longer for the stent group compared with angioplasty, with a median survival of 138 versus 61 d, respectively (aHR = 0.17; 95% confidence interval, 0.07 to 0.39; P < 0.001). The primary AVG patency for stent versus angioplasty was 91% versus 80% at 30 d, 69% versus 24% at 90 d, and 25% versus 3% at 180 d, respectively. The primary assisted AVF patency did not differ significantly between the stent and angioplasty groups. In patients dialyzing via AVF, multiple regression analysis revealed that stent placement was associated with improved after intervention peak Qa, 1627.50 ml/min versus 911.00 ml/min (β = 0.494; P = 0.008), change in Qa from before to after intervention, 643.54 ml/min versus 195.35 ml/min (β = 0.464; P = 0.012), and change in URR from before to after intervention, 5.85% versus 0.733% (β = 0.389; P = 0.039).Conclusions: Our results suggest that stent placement is associated with improved AVG primary assisted patency and improved AVF blood flow, which may significantly impact on dialysis adequacy.Despite a multitude of recent theoretical advances, emerging clinical data, and well-articulated guidelines, vascular access remains the Achilles heel of hemodialysis (1). The most common cause of dysfunction or loss of the arteriovenous access is thrombosis in the low flow state (2). The patency of arteriovenous grafts (AVGs) and arteriovenous fistulae (AVF) is compromised mainly by intimal hyperplastic lesions, which usually develop in areas of turbulent flow. These lesions tend to occur at sites of artery-to-vein or graft-to-vein anastomoses (3–5). Numerous studies have demonstrated the effectiveness of balloon angioplasty in the treatment of stenotic lesions, but this procedure is associated with a high rate of recurrent stenosis. Early studies of angioplasty reported 6-mo primary patency rates of only 31% to 64% (5–7).The limited success of intervention via angioplasty contributes to the inordinate amount of healthcare costs associated with end-stage renal disease and vascular access. The estimated total per person per year costs for hemodialysis access (grafts and fistulae) is greater than $9000, which is approximately a 40% increase from 1999 (8), at which time the annual cost of access related morbidity in the United States was estimated to be more than $1 billion (9). A large proportion of these costs encompass the morbidity associated with outpatient and inpatient procedures to salvage failed and failing access (8).Although endovascular stent placement is the standard of care in most percutaneous coronary and peripheral artery disease interventions, its role in the salvage of thrombosed and stenotic hemodialysis access remains controversial. Percutaneous transluminal angioplasty (PTA) of hemodialysis access has been described since the 1980s (10,11). It offers an alternative to surgical revision (jump grafts, graft interposition, venous patch angioplasty, and open thrombectomy) without the considerable morbidity, length of stay, and costs typically associated with surgery (12,13). Endovascular stent placement, on the other hand, has been used in the management of hemodialysis access stenosis since 1988 (14,15). Stents have been used predominantly as a salvage to failed angioplasty (venous rupture, elastic recoil, rapidly recurrent stenosis after PTA, or residual stenosis >30%) or as adjunctive therapy. Multiple studies have compared stent versus angioplasty in terms of access patency with mixed results (16–21). In these studies, multiple confounders, such as a wide variety of stent types, the nature and locations of the stenotic lesions, the access configuration, the blood flow measurements, and the case mix, prevent the clinician from drawing definitive conclusions regarding the use of stent versus angioplasty (22). A recent observational cohort study by Maya and Allon addressed some of the aforementioned limitations and demonstrated improved primary and secondary graft patency after thrombectomy of AVGs (23).The role of stent placement in the treatment of stenotic lesions (those not associated with thrombosis per se) in AVGs and AVF remains poorly defined. The objectives of our study are twofold: 1) to compare the effects of stent versus angioplasty on patency rates in the treatment of stenotic AVF and AVGs, controlling for age, gender, location of lesion, and stent type; and 2) to compare access flow (Qa) and urea reduction ratio (URR) between the two groups as a metric of the effect of stent placement versus angioplasty on dialysis delivery.     

The effect of extracorporeal high blood flow rate on left ventricular function during hemodialysis—an echocardiography study

The effect of increased extracorporeal blood flow rate on left ventricular (LV) function has been studied during volume-controlled bicarbonate hemodialysis. Ten stable patients on chronic hemodialysis, with a mean age of 28 years (range 19-38) were studied using two-dimensional and Doppler echocardiography. The mean time on hemodialysis was 32 months (range 3-60). All patients were investigated during three dialysis sessions on the first day of the week for 3 consecutive weeks. The blood flow rate was chosen randomly as 250, 350, or 450 cc/min. Apart from the time of hemodialysis and blood flow rate, other parameters of the hemodialysis were kept stable during all three sessions. Echocardiographic studies were done before, at mid dialysis, and during the last 15 min of each dialysis session. The following parameters were evaluated: heart rate, mean blood pressure, shortening fraction, ejection fraction, cardiac output, and pre-ejection period/LV ejection time ratio. The changes of the measured cardiac parameters at the beginning, middle and end of each session were not significantly different. Furthermore, the differences in changes between the three different sessions were comparable. Our results indicate that an increase in dialysis blood flow rate up to 450 cc/min does not have an adverse effect on the left ventricle in patients on maintenance hemodialysis and with stable cardiovascular function.     

Affinity Hemodialysis for Antiviral Therapy. I. Removal of HIV‐1 from Cell Culture Supernatants,Plasma, and Blood

Abstract: We tested an affinity hemodialysis technique designed to efficiently remove HIV and toxic viral proteins from blood. Miniature polyethersulfone hollow‐fiber dialysis cartridges (200–500 nm pore) were packed with anti‐HIV antibodies covalently coupled to agarose beads and sealed inside the cartridge. Cell culture fluids, plasma, or infected blood (7–15 ml) containing HIV‐1 were circulated over the cartridge at 0.7–10 ml/min and the rate of removal of HIV measured by PCR and p24 ELISA. The technique removed up to 98% of HIV‐1 particles from cell culture supernatants. Affinity hemodialysis also efficiently captured cultured HIV from human blood plasma (90%) and native HIV from infected blood (83% to 100%). Viral capture followed first‐order kinetics (t_1/2 = 2.8 h). Variations in antibody type, matrix linkage (protein G versus direct coupling), bead pore size, and temperature of operation (25–37°C) had only small effects. Although some binding was nonspecific, direct binding to the immobilized antibodies appeared to be the predominant mechanism.     

老年血液透析病人动静脉内瘘血流量对心功能及炎症反应的影响

目的 探讨老年血液透析病人动静脉内瘘血流量(AVFB)对心功能及炎症反应的影响.方法 选取2017年2月至2018年3月我院利用动静脉内瘘进行血液透析治疗的老年病人124例为研究对象,根据病人动静脉内瘘吻合术后1个月AVFB的流量大小,将病人分为高流量组(>600 mL/min,n=38)、中流量组(400～600 m...     

超声指导下介入治疗动静脉内瘘狭窄的应用

目的 探讨在超声指导下对动静脉内瘘（arterio-venous fistulas,AVF）狭窄的维持血液透析（hemodialysis,HD）患者进行经皮腔内血管成形术（percutaneous transluminal angioplasty,PTA）对手术即刻及远期疗效的影响.方法 选择2011年1月至2013年1月在广州市第一人民医院因AVF狭窄或闭塞住院并接受PTA介入治疗的慢性肾功能衰竭HD患者62例,分为对照组32例及超声组30例.对照组患者实施常规PTA,超声组患者则在超声指导下进行PTA.PTA术后对患者随访1年,记录随访期间AVF主要心血管事件（包括急性、亚急性血栓形成;扩张部位再狭窄、闭塞需再次PTA或外科造瘘;新发生的AVF狭窄致HD不充分）.结果 与对照组相比,超声组穿刺时间、PTA手术时间显著减少,差异有统计学意义[（5.41±1.92）min vs.（8.40±5.61）min,P＜0.01;（62.83±13.43）min vs.（71.56±17.98）min,P＜0.01].超声组穿刺并发症发生率降低且手术即时成功率有高于对照组趋势,但差异无统计学意义（3.3％ vs.15.6％,P＞0.05;96.6％ vs.87.5％,P＞0.05）.超声组术后超声多普勒AVF瘘口血流量显著高于对照组,差异有统计学意义[（537.62±33.09） mL/min vs.（519.25±35.06） mL/min,P＜0.01].Kaplan-Meier曲线分析结果显示,超声组随访期间无AVF主要心血管事件发生,其生存率显著高于对照组,差异有统计学意义（90.0％ vs.65.6％,Log rank=4.706,P=0.030）.结论 应用超声指导PTA处理AVF狭窄方便、安全,缩短手术操作时间并能改善手术即刻及远期疗效,具有一定的临床推广应用价值.     

Comparison of Solute Removal Properties Between High‐Efficient Dialysis Modalities in Low Blood Flow Rate

Blood flow (Qb) is one of the dialysis parameters most strongly influencing the performance of dialysis modalities. However, few studies have compared different dialysis modalities in patients with low Qb. We conducted a prospective, single‐center study in 21 patients. Each patient underwent four dialysis sessions with routine dialysis parameters: high‐flux hemodialysis (HD), predilution hemodiafiltration (pre‐HDF), expanded HD (HDx), and postdilution HDF (post‐HDF). The removal ratios (RR) of urea, creatinine, ß₂‐microglobulin, myoglobin, prolactin, α₁‐microglobulin, free kappa and lambda immunoglobulin light chains (?FLC and λFLC), α₁‐acid glycoprotein, and albumin were compared intraindividually. A proportional part of the dialysate was collected to quantify albumin loss. There were no differences in urea and creatinine RRs. The β₂‐microglobulin RR was higher in pre‐HDF and post‐HDF. Myoglobin and prolactin RRs were higher with HDx and post‐HDF. The α₁‐microglobulin and α₁‐acid glycoprotein RRs were significantly higher with post‐HDF than with other treatments, and RRs obtained with HDx were higher than obtained with HD and pre‐HDF. Free ?FLC and λFLC RRs showed the following results in ascending order: HD, pre‐HDF, HDx, and post‐HDF, most of them with statistical significance. Albumin loss varied from 0.45 g with HD to 3.5 g with post‐HDF. The global removal score values were 41.0 ± 4.8% with HD, 44.0 ± 5.2% with pre‐HDF, 49.5 ± 4.6% with HDx, and 54.8 ± 5.3% with post‐HDF, with significant differences between all treatment modalities. In conclusion, this study confirms the superiority of post‐HDF over high‐flux HD, pre‐HDF, and HDx in patients with low Qb. HDx was the closest alternative to post‐HDF and was clearly superior to HD and pre‐HDF. Finally, pre‐HDF was also superior to HD. With this Qb, there was a higher risk of underdialysis, both diffusive and convective, especially in patients with a session duration of less than 5 h.     

The Effects of Coronary Angioplasty on Nitroglycerin-Induced Augmentation of Regional Myocardial Blood Flow

Percutaneous transluminal coronary angioplasty (PTCA) may improve coronary vasomotor responses after relief of flow limiting luminal narrowings. To evaluate the effects of PTCA on nitro-glycerin-induced augmentation of coronary blood flow, great cardiac vein (thermodilution) blood flow and systemic hemodynamic responses to low (50 meg) and high (200 meg) dose intracoronary nitroglycerin (NTG) before and after PTCA were measured in 20 patients undergoing left anterior descending artery (LAD) balloon dilatation. Before PTCA, low dose NTG increased great vein flow 44 ±31% (from 56 ± 21 to 81 ± 33 mL/min, P < 0.01). High dose NTG increased great vein flow 55 + 30% (56 ± 23 to 87 ± 38 mL/min, P < 0.01). PTCA reduced LAD stenosis (79 ± 13 to 20 ± 9%, P < 0.01) and translesional pressure gradient (49 ± 10 to 15 ± 13 mmHg, P < 0.01) increasing post-PTCA basal great vein flow 45% (56 ± 21 mL/min to 81 ±27 mL/min, P < 0.01).
After PTCA, low dose NTG increased great vein flow only 26 ± 23% (81 ± 27 to 101 ± 39mL/min, P < 0.01; P < 0.05 versus 44 ± 31% before PTCA). The high dose NTG-induced coronary hy-peremic responses were unchanged after PTCA (55 ± 30, 55 ± 34%, P = ns). When compared to dose related NTG hyperemic responses in 10 patients with normal LAD, the post-PTCA responses remained attenuated.
These data indicate that NTG-induced augmentation of coronary blood flow remains unchanged or attenuated and does not appear to be improved by PTCA. These findings should be considered when evaluating pharmacological coronary blood flow responses after PTCA. These data also suggest that epicardial coronary resistance plays a limited role in NTG-induced augmentation of coronary blood flow inpatients with atherosclerotic coronary disease. (J Interven Cardiol 1988:1:2)     

Effect of Metoclopramide on Portal Blood Flow in Patients with Liver Cirrhosis,Measured by the Pulsed Doppler System

The effect of metoclopramide on portal blood flow, the maximal diameter of the portal vein, and some cardiovascular haemortynamic variables was studied in 10 patients with cirrhosis of the liver and portal hypertension. Portal vein haemo-dynamics were studied by the pulsed Doppler system. Within 15 min of intravenous administration of 20 mg metoclopramide, portal blood velocity and portal blood flow decreased significantly, from 11.2 ± 1.1 to 10.8 ± 1.2 cm/sec and from 769.0 ± 87.7 to 707.9 ± 84.2 ml/min, respectively (p < 0.001). Within about 30 min portal blood velocity and portal blood flow returned to basal values (p >0.05). The maximal diameter of the portal vein, systolic and diastolic blood pressure, and heart rate remained unchanged. These results support the hypothesis that metoclopramide, which raises lower oesophageal sphincter pressure and reduces intravariceal blood flow, significantly decreases the portal blood flow in cirrhotic patients with portal hypertension.