Risk factors predicting the successful function and use of autogenous arteriovenous fistulae for hemodialysis.

BACKGROUND: For patients with end-stage renal failure hemodialysis with an autogenous arteriovenous fistula (AVF) has proven to be the ideal vascular access. OBJECTIVE: The aim of this study is to discover potential predictors of a well-functioning hemodialysis fistula. METHODS: From December 2009 to March 2011, 80 patients undergoing first time AVF creation were enrolled in our retrospective study. We analyzed pre- and postoperative vessel diameters and flow characteristics gained by duplex ultrasonography (DUS) and intraoperative ultrasound transit-time flow measurements regarding intraoperative blood flow and pulsatility index (PI). Follow-up was defined until the end of the first month with regular hemodialysis, 10 weeks after AVF creation. We performed statistical analyses by employing Spearman correlation, t test, analysis of variance, χ2 test, and receiver operating characteristics (ROC). RESULTS: At the end of the follow-up, 62 patients (78%) featured functioning AVFs and 18 patients (22%) featured nonfunctioning AVFs. Factors influencing AVF function were radial artery diameter (χ2 = 5.23, p = 0.02), intraoperative flow (χ2 = 7.09, p = 0.01), intraoperative PI (χ2 = 6.5, p = 0.01), and postoperative flow (χ2 = 16.29, p = 0.01). According to the ROC analyses, we could develop cut-off values for predicting an ideal AVF function: radial artery diameter more than 2.3 mm, cephalic vein diameter more than 2.7 mm, intraoperative mean flow more than 113 mL/min, PI less than 1.4, and postoperative mean flow more than 160 mL/min. CONCLUSION: Intraoperative ultrasound transit-time flow measurements gained at surgery and postoperative follow-up with DUS can help identify AVFs that are unlikely to function and therefore need early intervention.

Comparison of the diagnostic performance of three natriuretic peptides in hemodialysis patients: which is the appropriate biomarker?.

BACKGROUND: Plasma concentrations of natriuretic peptides are often elevated in chronic hemodialysis patients and difficult to interpret due to accumulation, high incidence of cardiac disease and changes in volume status. Mid-regional pro-ANP is a newly developed assay whereas BNP and its fragment NT-pro-BNP are available for a longer time. In this cross-sectional study, we compared the plasma concentration of MR-pro-ANP, BNP and NT-pro-BNP in stable ambulatory hemodialysis patients (n = 239) and investigated their associations with clinical factors such as residual diuresis, cardiac status and interdialytic weight gain and with mortality. METHODS AND RESULTS: In all patients enrolled, the plasma concentration of all natriuretic peptides were largely elevated with a median concentration of 337 pg/ml (interquartile range 146-684) for BNP, 4435 pg/ml (1687-16228) for NT-proBNP and 907 pmol/L (650-1298) for MR-pro-ANP. Plasma concentration of all natriuretic peptides correlated independently with age, degree of systolic dysfunction and negatively with residual diuresis. Dependency on residual renal clearance was strongest for the fragments MR-pro-ANP and NT-pro-BNP. The plasma concentration of all natriuretic peptides was associated with mortality within 2 years of follow-up. Receiver-operated curves revealed a low sensitivity (32-45%), but high specificity for all natriuretic peptides (85-93%) resulting in a high negative predictive (82-87%). Best cut-off values obtained from were 18 611 pg/ml for NT-pro-BNP, 958 pg/ml for BNP and 1684 pmol/L for MR-pro-ANP. CONCLUSIONS: In hemodialysis patients, the fragments NTproBNP and MR-pro-ANP are largely elevated compared to BNP which is explained by accumulation. The prognostic performance of MR-pro-ANP is similar to that of NT-pro-BNP or BNP.

The nonselective beta-blocker carvedilol suppresses apoptosis in human cardiac tissue: a pilot study.

BACKGROUND: Cardioplegia and reperfusion of the myocardium may be associated with cardiomyocyte apoptosis and subsequent myocardial injury. To establish a pharmacologic strategy for the prevention of these events, this study aimed to verify the reliability of our human cardiac model and to evaluate the antiapoptotic properties of the nonselective beta-blocker carvedilol during simulated cardioplegia and reperfusion ex vivo. METHODS: Cardiac biopsies were retrieved before induction of cardiopulmonary bypass from the auricle of the right atrium of patients undergoing elective coronary artery bypass grafting. Biopsies were exposed to ex vivo conditions of varying periods of cardioplegia/reperfusion (30/10 minutes, 60/20 minutes, 120/40 minutes). Group I was the untreated control (n = 15), group II was the treated control (cardioplegia/reperfusion, n = 15), and group III was the experimental group (cardioplegia/reperfusion plus carvedilol, n = 15). Immunostaining for antibodies to activated caspase 3 and poly(ADP-ribose) polymerase 1 (PARP-1) cleavage was used to detect apoptosis. RESULTS: The percentage of apoptotic cardiomyocytes was significantly lower (P < .05) in group I than in group II, revealing a time-dependent increase. In group III, carvedilol treatment suppressed apoptosis significantly (P < .05). CONCLUSION: Carvedilol significantly suppresses apoptosis in our ex vivo setting. This finding warrants further studies to evaluate the potential beneficial effects of carvedilol in suppressing ischemia/reperfusion injury in clinical settings.

Human duodenal spheroids for noninvasive intracellular pH measurement and quantification of regulation mechanisms under physiological conditions.

Three-dimensional cell cultures (spheroids) of biopsies of human duodenum were used to develop a new noninvasive method for studying intercellular and intracellular mechanisms. Through examinations of intracellular pH regulation, high functional similarity to native tissue could be shown, as already evidenced morphologically. A special microperfusion chamber was developed to fix individual spheroids physically to a nylon net, via laminar perfusion flow through the chamber. A significant improvement over current fixation methods was shown by the increase of cell viability almost up to 100%. Viability of the spheroids was confirmed by trypan blue exclusion, by a LIVE/DEAD viability/cytotoxicity kit, and by BCECF distribution. Intracellular pH was measured by use of the pH-sensitive fluorescence dye BCECF. To investigate the intracellular pH regulation, spheroid-like vesicles were acidified by NH4Cl prepulse technique. The subsequent active intracellular pH recovery was blocked with Na+-free Krebs Henseleit (KH) solution, with amiloride KH (inhibitor of the Na+-H+-exchanger), or with H2DIDS KH (inhibitor of the HCO3(-)-Cl(-)-exchanger and Na+-HCO3(-)-cotransporter). The intracellular pH of the spheroids was 7.31 +/- 0.05. pH-backregulation after acidification was prevented by sodium-free buffer, amiloride, and H2DIDS. These experiments indicated the presence of a Na+-H+-exchanger and a Na+-HCO3(-)-cotransporter. In conclusion, the human duodenal spheroid is an excellent physiological system for in vitro studies of the human duodenum.

Clinical outcome and quality of life after reoperative CABG: off-pump versus on-pump - observational pilot study.

BACKGROUND: Coronary artery bypass grafting (CABG) on cardiopulmonary bypass (CBP) is associated with significant morbidity and mortality. In high-risk patients, doomed for reoperation the adverse effects of CBP may be more striking. We evaluated the results of reoperative CABG (redo-CABG) by either off-pump (OPCAB) or on-pump (ONCAB). Clinical endpoints were perioperative myocardial infarction, mortality, survival and as the most striking difference between prior studies the quality of life (QoL). METHODS: We performed a prospective, non-randomized assessment for patients who underwent redo-CABG by redo-OPCAB (n=40) or redo-ONCAB (n=40) at our institution between January 2007 and December 2010. For evaluation of QoL the SF-36 health survey was used with self-administered assessment. RESULTS: During follow-up 37 of 40 patients were alive in the redo-OPCAB group versus 32 of 40 patients in the redo-ONCAB group (p<0.05). The shorter operation time, less blood loss, fewer perioperative myocardial infarctions, the higher rate of totally arterial revascularisation and shorter intensive care stay were the significantly beneficial differences for patients in the redo-OPCAB group (p<0.05). The 3-year survival rate was higher in the redo-OPCAB group with 81 ± 12% versus 63 ± 9%in the redo-ONCAB group. The quality of life survey did not reveal any significant differences between both groups. CONCLUSION: In conclusion, with our present retrospective study, we could demonstrate the safety and efficacy of the redo-OPCAB technique with even higher 3-year survival rate. Both techniques seem to have similar impact on the outcome of patients.

[Heart and kidney--only together they are strong. On the cardiorenal and renocardiac syndrome. Case 5/2011]. / Herz und Nieren--nur gemeinsam sind sie stark. Über das kardiorenale und renokardiale Syndrom. Fall 5/2011.

HISTORY AND ADMISSION FINDINGS: We report on two patients with cardiorenal and renocardiac syndrome, respectively, who were treated with peritoneal dialysis. INVESTIGATIONS: Patient 1 suffered from dilated cardiomyopathy with an ejection fraction of 20%. There was no hint for an intrinsic renal disease, urinalysis showed microalbuminuria at the most. Due to progressive cardiac forward failure kidney dysfunction and diuretic-refractory volume retention developed. Patient 2 was admitted with an uremic syndrome and newly developed atrial fibrillation. Echocardiography revealed a hitherto unknown dilated cardiomyopathy. DIAGNOSIS, TREATMENT AND COURSE: Both patients were treated with continuous ambulatory peritoneal dialysis. This led to regression of the uremic complications. Sinus rhythm was restored in patient 2 after two weeks and cardiomyopathy was reversed after another 9 months. CONCLUSIONS: End-stage heart failure results in kidney dysfunction which can progress to a dialysis-dependent state. End-stage renal failure is often accompanied by cardiac dysfunction and failure.

The challenge to verify ceramide's role of apoptosis induction in human cardiomyocytes--a pilot study.

BACKGROUND: Cardioplegia and reperfusion of the myocardium may be associated with cardiomyocyte apoptosis and subsequent myocardial injury. In order to establish a pharmacological strategy for the prevention of these events, this study aimed to verify the reliability of our human cardiac model and to evaluate the pro-apoptotic properties of the sphingolipid second messenger ceramide and the anti-apoptotic properties of the acid sphingomyelinase inhibitor amitryptiline during simulated cardioplegia and reperfusion ex vivo. METHODS: Cardiac biopsies were retrieved from the right auricle of patients undergoing elective CABG before induction of cardiopulmonary bypass. Biopsies were exposed to ex vivo conditions of varying periods of cp/rep (30/10, 60/20, 120/40 min). Groups: I (untreated control, n = 10), II (treated control cp/rep, n = 10), III (cp/rep + ceramide, n = 10), IV (cp/rep + amitryptiline, n = 10) and V (cp/rep + ceramide + amitryptiline, n = 10). For detection of apoptosis anti-activated-caspase-3 and PARP-1 cleavage immunostaining were employed. RESULTS: In group I the percentage of apoptotic cardiomyocytes was significantly (p < 0.05) low if compared to group II revealing a time-dependent increase. In group III ceramid increased and in group IV amitryptiline inhibited apoptosis significantly (p < 0.05). In contrast in group V, under the influence of ceramide and amitryptiline the induction of apoptosis was partially suppressed. CONCLUSION: Ceramid induces and amitryptiline suppresses apoptosis significantly in our ex vivo setting. This finding warrants further studies aiming to evaluate potential beneficial effects of selective inhibition of apoptosis inducing mediators on the suppression of ischemia/reperfusion injury in clinical settings.

Ultrasound estimation of volume of postoperative pleural effusion in cardiac surgery patients.

The aim of this study was to establish a practical simplified formula to facilitate the management of a frequently occurring postoperative complication, pleural effusion. Chest ultrasonography with better sensitivity and reliability in the diagnosis of pleural effusions than chest X-ray can be repeated serially at the bedside without any radiation risk. One hundred and fifty patients after cardiac surgery with basal pleural opacity on chest X-ray have been included in our prospective observational study during a two-year period. Effusion was confirmed on postoperative day (POD) 5.9+/-3.2 per chest ultrasound sonography. Inclusion criteria for subsequent thoracentesis based on clinical grounds alone and were not protocol-driven. Major inclusion criteria were: dyspnea and peripheral oxygen saturation (SpO(2)) levels < or = 92% and the maximal distance between mid-height of the diaphragm and visceral pleura (D > or = 30 mm). One hundred and thirty-five patients (90%) were drained with a 14-G needle if according to the simplified formula: V (ml)=[16 x D (mm)] the volume of the pleural effusion was around 500 ml. The success rate of obtaining fluid was 100% without any complications. There is a high accuracy between the estimated and drained pleural effusion. Simple quantification of pleural effusion enables time and cost-effective decision-making for thoracentesis in postoperative patients.

Human cardiac tissue in a microperfusion chamber simulating extracorporeal circulation--ischemia and apoptosis studies.

BACKGROUND: After coronary artery bypass grafting ischemia/reperfusion injury inducing cardiomyocyte apoptosis may occur. This surgery-related inflammatory reaction appears to be of extreme complexity with regard to its molecular, cellular and tissue mechanisms and many studies have been performed on animal models. However, finding retrieved from animal studies were only partially confirmed in humans. To investigate this phenomenon and to evaluate possible therapies in vitro, adequate human cardiomyocyte models are required. We established a tissue model of human cardiomyocytes preserving the complex tissue environment. To our knowledge human cardiac tissue has not been investigated in an experimental setup mimicking extracorporeal circulation just in accordance to clinical routine, yet. METHODS: Cardiac biopsies were retrieved from the right auricle of patients undergoing elective coronary artery bypass grafting before cardiopulmonary bypass. The extracorporeal circulation was simulated by submitting the biopsies to varied conditions simulating cardioplegia (cp) and reperfusion (rep) in a microperfusion chamber. Cp/rep time sets were 20/7, 40/13 and 60/20 min. For analyses of the calcium homoeostasis the fluorescent calcium ion indicator FURA-2 and for apoptosis detection PARP-1 cleavage immunostaining were employed. Further the anti-apoptotic effect of carvedilol [10 microM] was investigated by adding into the perfusate. RESULTS: Viable cardiomyocytes presented an intact calcium homoeostasis under physiologic conditions. Following cardioplegia and reperfusion a time-dependent elevation of cytosolic calcium as a sign of disarrangement of the calcium homoeostasis occurred. PARP-1 cleavage also showed a time-dependence whereas reperfusion had the highest impact on apoptosis. Cardioplegia and carvedilol could reduce apoptosis significantly, lowering it between 60-70% (p < 0.05). CONCLUSIONS: Our human cardiac preparation served as a reliable cellular model tool to study apoptosis in vitro. Decisively cardiac tissue from the right auricle can be easily obtained at nearly every cardiac operation avoiding biopsying of the myocardium or even experiments on animals.The apoptotic damage induced by the ischemia/reperfusion stimulus could be significantly reduced by the cold crystalloid cardioplegia. The additional treatment of cardiomyocytes with a non-selective beta-blocker, carvedilol had even a significantly higher reduction of apoptotis.

The challenge to detect heart transplant rejection and transplant vasculopathy non-invasively - a pilot study.

BACKGROUND: Cardiac allograft rejection and vasculopathy are the main factors limiting long-term survival after heart transplantation.In this pilot study we investigated whether non-invasive methods are beneficial to detect cardiac allograft rejection (Grade 03 R) and cardiac allograft vasculopathy. Thus we compared multi-slice computed tomography and magnetic resonance imaging with invasive methods like coronary angiography and left endomyocardial biopsy. METHODS: 10 asymptomatic long-term survivors after heart transplantation (8 male, 2 female, mean age 52.1 +/- 12 years, 73 +/- 11 months after transplantation) were included. In a blinded fashion, coronary angiography and multi-slice computed tomography and ventricular endomyocardial biopsy and magnetic resonance imaging were compared against each other. RESULTS: Cardiac allograft vasculopathy and atherosclerosis were correctly detected by multi-slice computed tomography and coronary angiography with positive correlation (r = 1). Late contrast enchancement found by magnetic resonance imaging correlated positively (r = 0.92, r2 = 0.85, p < 0.05) with the histological diagnosis of transplant rejection revealed by myocardial biopsy. None of the examined endomyocardial specimen revealed cardiac allograft rejection greater than Grade 1 R. CONCLUSION: A combined non-invasive approach using multi-slice computed tomography and magnetic resonance imaging may help to assess cardiac allograft vasculopathy and cardiac allograft rejection after heart transplantation before applying more invasive methods.

Late desaturation due to collateral veins 10 years after total cavopulmonary shunt in left atrial isomerism: surgical closure.

The development of systemic collateral veins after palliative surgery in children with univentricular circulation is a common complication, however, manifestation as late as 10 years postoperatively is rare. Massive systemic to hepatic venous collaterals developed in a 14-year-old girl with univentricular heart, situs inversus atriovisceralis and hemiazygos continuity to the left-sided superior vena cava, 10 years after Kawashima operation. The resulting azygoportal shunt had led to a progressive systemic desaturation and reduction in ventricular function. Interventional occlusion was supposed to be risky for renal failure due to potential closure of the renal vein so that surgical closure was performed. The saturation persistently increased from 65% to more than 85% postoperatively.

Severe pulmonary valve incompetence late after debanding: repair by bicuspidization.

We report a simple valve repair for severe pulmonary incompetence in a 25-year-old patient. The patient had been operated on twice before for ventricular septal defect and coarctation of the aorta. The first operation consisted of pulmonary artery banding and coarctectomy and end-to-end anastomosis at 4 months, followed by debanding and transinfundibular ventricular septal defect closure at 6 years of age. Massive pulmonary incompetence was due to destruction of one valve cusp with the right ventricular outflow tract and pulmonary artery dilated secondarily. Repair consisted of pulmonary valve bicuspidization and right ventricular remodelling.