Comparison of mechanical support with Impella or extracorporeal life support in post-cardiac arrest cardiogenic shock: a propensity scoring matching analysis

Background

Out of hospital cardiac arrest (OHCA) is a major public health problem and a leading cause of death in industrialized nations. Post-cardiac arrest cardiogenic shock (CS) occurs frequently after resuscitation from CA and may lead to multi-organ failure and death, even in patients with good neurologic prognosis. Mechanical circulatory support (MCS) may be considered at that time in order to augment cardiac output, stabilize hemodynamics and ensure adequate organ perfusion. However, optimal selection of the device type remains unclear and, so far, no specific guideline recommendation exists. The Impella pump and extracorporeal circulatory support (ECLS) are the most frequently used device types for temporary percutaneous MCS in this context.

Purpose

Our aim was to compare outcomes of Impella with extracorporeal life support (ECLS) in patients with post-cardiac arrest cardiogenic shock (CS) complicating acute myocardial infarction (AMI).

Methods

Reetrospective study of patients resuscitated from OHCA with post-cardiac arrest CS following AMI (May 2015 to May 2020) treated with MCS in terms of Impella or ECLS. Outcomes were compared using propensity score-matched analysis to account for differences in baseline characteristics between groups of MCS.

Results

159 patients were included (Impella, n=105; ECLS, n=54). Hospital and 12-month survival rates were comparable in the Impella and the ECLS group (p=0.16 and p=0.3, respectively). After adjustment for baseline differences, both groups demonstrated comparable hospital and 12-month survival (p=0.36 and p=0.64, respectively) (Figure 1). Impella patients had a significantly greater left ventricle ejection-fraction (LVEF) improvement at 96 hours (p<0.01 vs p=0.44 in ECLS) and significantly fewer device-associated complications than ECLS patients (15.2% versus 35.2%, p<0.01 for relevant access site bleeding, 7.6% versus 20.4%, p=0.04 for limb ischemia requiring intervention). In subgroup analyses, Impella was associated with better survival in patients with lower-risk features (lactate <8,6 mmol/L, time from collapse to return of spontaneous circulation <28 min, vasoactive score <46 and Horowitz index >182) (Figure 2).

Conclusions

In the biggest so far homogenous study of OHCA, the use of Impella 2.5/CP or ECLS in post-cardiac arrest CS after AMI was associated with comparable adjusted hospital and 12-month survival. Impella patients had a greater LVEF improvement than ECLS patients, while it was associated with a better survival in patients with low risk profile after OHCA. Device-related access-site complications occurred more frequently in patients with ECLS than Impella support.

Funding Acknowledgement

Type of funding sources: None.

The MARPELLA risk score for prediction of mortality in all-cause refractory cardiogenic shock treated with microaxial transvalvular pump: the MARPELLA study

Background

Although Impella may serve as an alternative strategy in order to stabilize the heart function without the detrimental effects of catecholamines or to bridge the patients in definite therapies in the setting of cardiogenic shock (CS), leading to a widespread use of this device, data concerning reliable prediction or predefining which patients would benefit from the implantation of such a device are completely lacking.

Purpose

To evaluate and to compare the prognostic accuracy of the Acute-Physiology-And-Chronic-Health II (APACHE II), the Simplified-Acute-Physiology-Score II (SAPS II), the Sepsis-related-organ-failure-assessment (SOFA), the intra-aortic-balloon-pump (IABP), the CardShock Score in refractory CS treated with Impella 2.5/CP. Moreover, we aimed to assess the prediction-of-Cardiogenic-shock-Outcome-foR-AMI-patients-salvaGed by VA-ECMO (ENCOURAGE) and the Survival-after -Veno-Arterial-extracorporeal-membranoxygenation (VA-ECMO) (SAVE) score, though initially for VA-ECMO patients created, in patients with CS as well as to develop a new prognostic score in this setting.

Methods

Single center study of consecutive Impella patients with CS admitted to Cardiology department of our university, from February 2013 until December 2020.

Results

A total of 401 patients were included in the analysis. 31% of the patients were supported with Impella CP, whereas 153 (38,1%) patients were resuscitated prior admission. Causes of CS was acute myocardial infarction in 311 (77,5%) patients, followed by dilatative cardiomyopathy/myocarditis (11,1%) and aortic stenosis (6%). The expected mortality according to scores was: SOFA 50%, SAPS II 70%, IABP Shock 55%, CardShock 60%, APACHE II 65%, ENCOURAGE 75% and SAVE score 70%. We observed a survival of 48,9% on hospital discharge and 45,6% after 12 months follow-up. Among the traditional scores estimated, the ENCOURAGE score was the most effective predictive model of mortality outcome presenting a moderate area under curve (AUC) of 0.72, followed by the CardShock, which derived an AUC of 0,7. The SAPS II, SOFA, IABP and the SAVE scores failed to predict outcome in this setting. According to the main predictors of outcome in our population derived from univariate analysis (vasoactive score >31, lactate>4,7 mmol/l, pH<7,31, Creatinine>1,33 mg/dl, Horowitz Index<238, age>71 years and prior resuscitation) as well as the odds ratio derived from binary regression analysis on mortality, a new score, the MARPELLA score, was created. This score reached an AUC of 0.83 (Figure 1). A mortality of 37%, 62% and 83,2% was observed in the low-, intermediate and high-risk group of the MARPELLA score, respectively (Figure 2).

Conclusion

MARPELLA Score is a new more potent score in the setting of all-cause CS that may guide clinicians to optimize the therapy in this group of patients, outweighing the traditional CS and intensive care unit scores.

Funding Acknowledgement

Type of funding sources: None.

Biventricular unloading with impella and venoarterial extracorporeal membrane oxygenation in severe refractory cardiogenic shock: prognosis and implications from the combined use of the devices

Background

Patients with refractory cardiogenic shock (RCS) may present with left ventricle (LV)-failure, biventricular failure or even combined cardiopulmonary failure. Mechanical support with Impella or veno-arterial membrane oxygenation (VA-ECMO) have emerged as an alternative strategy in order to stabilize the heart function without the detrimental effects of catecholamines or to bridge the patients in definite therapies. However, the selection of the appropriate MCS should be tailored according to the underlying pathophysiology and properties of the respective MCS device. Patients with Impella who initially presented with univentricular LV failure may develop additionally right ventricle (RV) dysfunction or pulmonary failure whereas patients with VA-ECMO may show signs of LV overloading, causing pulmonary edema, LV distension and thus compromising LV myocardial recovery.

Purpose

To present the main outcomes and predictors of survival and safety in RCS treated with Impella and VA-ECMO.

Methods

Single center study of consecutive patients with biventricular unloading with Impella and VA-ECMO for RCS admitted to Cardiology department of Philipps University in Marburg, Germany, from February 2013 until December 2019. The selection of the device was based on a standard algorithm (Figure 1).

Results

A total of 67 patients was included in the study. Mean age was 61.07±10.7 and 54 (80.6%) patients were male. Main cause of RCS was acute myocardial infarction (AMI) (74.6%), while 44 (65.7%) were resuscitated prior to admission. In 28 patients Impella was implanted first, whereas VA-ECMO was the first MCS device in 39 patients. The mean Simplified Acute Physiology Score II (SAPS II) and Sequential Organ Failure Assessment Score (SOFA) score on admission was 73.54±16.03 and 12.25±2.71, respectively, corresponding to an expected mortality of higher than 80%. Vasopressor doses and lactate levels were significantly decreased within 72 h on biventricular support (p<0.05 for both). Overall, 17 (25.4%) patients were discharged to cardiac rehabilitation and 5 patients (7.5%) were bridged successfully to ventricular assist device implantation, leading to a total of 32.8% survival on hospital discharge. The 6-month survival was 31.3%. Lactate >6 mmol/L, vasoactive score >100 and pH <7.26 on initiation of biventricular support, as well as Charlson comorbity index (CCI) >3 and prior resuscitation were independent predictors of survival (Figure 2).

Conclusions

Biventricular support with Impella and VA-ECMO in patients with RCS is feasible and efficient leading to a better survival than predicted through traditional risk scores, mainly via significant hemodynamic improvement and reduction in lactate levels. Lactate, pH and vasoactive score on initiation of biventricular support, as well as age-adjusted CCI and prior resuscitation are independent risk factors associated with mortality in this group of patients.

Funding Acknowledgement

Type of funding sources: None.

Left ventricle unloading and valvular integrity following microaxial mechanical circulatory support: a two year follow-up study

Background

Although the use of mechanical circulatory support (MCS) systems may improve the outcome of patients with cardiogenic shock (CS) due to myocardial infarction, little is known about its effect on the long-term structural integrity of left-ventricular (LV) valves as well as on the development of LV- architecture.

Methods

84 consecutive patients were monitored over 2 years having received microaxillar MCS device (ImpellaTM CP or 2.5) for complete coronary revascularization followed by optimal medical treatment.

Results

62 patients were treated for severe cardiogenic shock and compared with 22 patients receiving short-term microaxillar MCS for high risk percutaneous coronary interventions (PCI). 24 patients of the total population received Impella CP (14F motor pump) and the remaining 60 patients received Impella 2.5 (12F motor pump). Beside a significant increase in LV-ejection fraction after 2 years (p≤0.03 vs. pre implantation) in total cohort, we observed a statistically significant decrease in LV-dilation (p<0.001) and the severity of mitral valve regurgitation (p=0.007) in the 2 year follow-up period suggesting an improved LV-architecture. Neither the duration of support, nor the size of the MCS device or the indication for its use revealed any devastating impact on aortic or mitral valve integrity.

Conclusions

These findings indicate that beside complete revascularization and optimal medical treatment, microaxillar transvalvular MCS device supports the restoration of LV-architecture without detrimental long-term effects on the structural integrity of LV valves regardless of the size of the device or the duration of support.

Funding Acknowledgement

Type of funding source: None

Early Impella support in post-cardiac arrest cardiogenic shock complicating acute myocardial infarction improves short and long term survival

Background

Early mechanical circulatory support with Impella may improve survival outcomes in the setting of post-cardiac arrest cardiogenic shock (CS) after out of hospital cardiac arrest (OHCA) complicating acute myocardial infarction (AMI). However, the optimal timing to initiate mechanical circulatory support (MCS) in this particular setting remains unclear.

Purpose

We aimed to compare survival outcomes of patients supported with Impella 2.5 before percutaneous coronary intervention (PCI) (pre-PCI) to those supported after PCI (post-PCI).

Methods

Single center study of patients resuscitated from OHCA due to AMI with post-cardiac arrest CS between September 2014 and June 2018. Survival outcomes were compared between those with Impella support before and after PCI.

Results

A total of 65 consecutive patients with infarct-related post-cardiac arrest shock supported with Impella 2.5 during admission coronary angiogram were included. All patients were in profound CS requiring catecholamines on admission. Overall survival to discharge and at 12-months was 44.6% and 41.5%, respectively. Patients in the pre-PCI group had a higher survival to discharge and at 12-months as compared to patients of the post-PCI group (60.7% versus 32.4%, p=0.03 and 57.1% versus 29.7%, p=0.04, respectively). Moreover, the patients in the early support group demonstrated a greater functional recovery of the left ventricle when Impella support was initiated prior to PCI.

Conclusions

Our results suggest that the early initiation of MCS with Impella 2.5 prior to PCI is associated with improved hospital and 12-month survival in patients with post-cardiac arrest CS complicating AMI.

Figure 1

Funding Acknowledgement

Type of funding source: None

[Cardiac causes of chest pain]

Because of the life-threatening character and a high prevalence in emergency rooms, cardiac causes are important differential diagnoses of acute chest pain with the need for rapid clarification. In this context the working diagnosis "acute coronary syndrome" (ACS) plays a major role. In a synopsis of the clinical presentation, medical history, electrocardiogram and analysis of cardiac biomarkers, ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI) and unstable angina pectoris can be specified as entities of ACS. The treatment of ACS consists of an immediate anti-ischemic therapy, anti-thrombotic therapy and invasive coronary diagnostics with subsequent interventional or operative revascularization therapy. The timing of invasive management is essentially determined by the individual patient risk, with the exception of STEMI where interventional revascularization must be undertaken within 120 min of diagnosis. In this context the GRACE 2.0 and TIMI risk score have become established as reliable tools. Another rare but fatal cause of acute chest pain is aortic dissection. An abrupt onset of tearing and sharp chest pains, deficits in pulse as well as the presence of high-risk factors, such as advanced age, arterial hypertension, atherosclerosis, known collagenosis and previous aortic or coronary artery procedures are highly indicative for aortic dissection and additional diagnostic imaging and the highly sensitive D‑dimer should be undertaken. Additionally, inflammatory diseases, such as pericarditis and myocarditis can be associated with chest pains and mimic the character of ACS and should also be considered in the differential diagnostics.

Deciphering the fine-structure of tribal admixture in the Bedouin population using genomic data

The Bedouin Israeli population is highly inbred and structured with a very high prevalence of recessive diseases. Many studies in the past two decades focused on linkage analysis in large, multiple consanguineous pedigrees of this population. The advent of high-throughput technologies motivated researchers to search for rare variants shared between smaller pedigrees, integrating data from clinically similar yet seemingly non-related sporadic cases. However, such analyses are challenging because, without pedigree data, there is no prior knowledge regarding possible relatedness between the sporadic cases. Here, we describe models and techniques for the study of relationships between pedigrees and use them for the inference of tribal co-ancestry, delineating the complex social interactions between different tribes in the Negev Bedouins of southern Israel. Through our analysis, we differentiate between tribes that share many yet small genomic segments because of co-ancestry versus tribes that share larger segments because of recent admixture. The emergent pattern is well correlated with the prevalence of rare mutations in the different tribes. Tribes that do not intermarry, mostly because of social restrictions, hold private mutations, whereas tribes that do intermarry demonstrate a genetic flow of mutations between them. Thus, social structure within an inbred community can be delineated through genomic data, with implications to genetic counseling and genetic mapping.

[44-year-old patient with fulminant liver failure]

The 44-year old female patient was admitted with acute hepatic failure and extensive haemolysis under the preliminary diagnosis of Wilson's disease. General characteristic criteria of Wilson's disease as Kayser-Fleischer ring, low serum copper and low ceruloplasmin levels were not observed. The preliminary diagnosis of acute Wilson's disease was established on the basis of the characteristic laboratory values with an AP/bilirubin ratio <2, an AST/ALT ratio >4, accompanying hemolysis and a highly elevated cupruresis. The definitive diagnosis of Wilson's disease was verified after orthotopic liver transplantation by quantitative copper evaluation in the explanted liver. The case represents the yet oldest patient reported with an acute manifestation of Wilson's disease.

Use of the robot system Da Vinci for laparoscopic repair of gastro-oesophageal reflux in children

In adult patients, laparoscopic surgery, using a robot system (Da Vinci, Intuitive Surgical, Mountain View, California), has been recently introduced into surgical practice. To investigate the feasibility of the system in paediatric surgery, laparoscopic fundoplications as well as cholecystectomies have been performed. In July 2000 we used the robot system for the first time on an 11-year-old girl with gastro-oesophageal reflux, and since that time on 7 other children. Altogether 5 Thal and 3 Nissen procedures have been carried out. The average age was 12 years, with a range of 7 to 16 years. All operations were performed without complications and without conversion to open surgery. The medium operating time was 146 min with a range of 105 to 180 minutes. Compared to conventional laparoscopy, the 3-dimensional high-quality vision, the advanced instrument movements and the ergonomic position of the surgeon seems to enhance surgical precision. In our opinion, the use of the robot system is feasible and safe in paediatric surgery. The technique is limited due to the fact that instruments adapted to the size of small children are not yet available.

Early experiences of robotic surgery in children

BACKGROUND

Laparoscopic surgery using a robotic system (Da Vinci) was recently introduced into surgical practice for adult patients. To investigate the feasibility of this system in pediatric surgery, laparoscopic fundoplication (Thal and Nissen), cholecystectomy, and bilateral salpingo-oophorectomy were performed.

METHODS

Eleven children with a mean age of 12 years (range, 7-16 years) underwent either laparoscopic anterior partial fundoplication (Thal, n = 8) or Nissen fundoplication (n = 3) for correction of gastroesophageal reflux disease in the presence of uncontrolled symptoms of regurgitation and pulmonary infection. Two children underwent laparoscopic cholecystectomy due to symptomatic cholecystolithiasis. One child underwent bilateral salpingo-oophorectomy due to a gonadoblastoma.

RESULTS

Mean operating time for fundoplication was 146 min (range, 105-180 min), the operating times for cholecystectomy were 150 and 105 min, and that for salpingo-oophorectomy was 95 min. No complications were registered during either the robotic procedures or the postoperative courses.

CONCLUSIONS

Compared to conventional laparoscopy, the three-dimensional high-quality vision, advanced instrument movement, and improved ergonomic position of the surgeon appear to enhance surgical precision. Robotic surgery in children using the Da Vinci system seems to be feasible and safe. However, the technique is limited due to the fact that instruments adapted to the size of small children are not available. Furthermore, the high costs and prolonged system setup are disadvantages.

Impact of cyclosporine and low-dose steroid therapy on insulin sensitivity and beta-cell function in patients with long-term liver grafts

To examine whether factors controlling glucose tolerance, i.e., insulin sensitivity (SI) and first-(phi1) and second-phase insulin secretion (phi2), are impaired in after orthotopic liver transplantation (OLT), they were assesssed in patients that had undergone OLT for cirrhosis (n = 10) with cyclosporin A and low-dose steroid therapy (5 mg prednisone per day) and were compared with those of healthy matched control subjects (n = 10). These factors were determined by means of computer-based analysis of frequently sampled intravenous glucose tolerance tests (FSIGTT). Glucose and insulin profiles (posthepatic insulin) did not differ between both groups, whereas C-peptide levels (prehepatic insulin) were elevated in the transplant group after the FSIGTT, indicating an increased hepatic insulin degradation. SI and (phi1 did not differ between both groups. phi2, however, was significantly enhanced (23.94 +/- 2.63 vs 13.88 +/- 1.25 min(-1), P < 0.05). These results indicate that cyclosporine and low-dose steroid therapy do not impair SI and phi1. However, enhanced phi2 compensates the increased hepatic insulin clearance.

[Robot-assisted laparoscopic cholecystectomy and fundoplication--initial experiences with the Da Vinci system]

We report on our first five robot-assisted laparoscopic cholecystectomies and one fundoplication (Da Vinci system). No postoperative complications were observed. For the cholecystectomies (three elective and two acute cases) mean operation time was 1 h 35 min, and mean hospital stay was 5 days; for fundoplication the operation time was 2 h 15 min. The main advantages seem to be improved visualization by using a stereo camera und ease of precise dissection by micromechanical instruments directed by masterslaves from a distant console. The main disadvantage is the high cost. To fully evaluate the benefit for the patient, prospective clinical trials are warranted.

[A modular retraction system (VarioLift) for laparoscopy without pneumoperitoneum]

Because of adverse physiological effects and technical disadvantages of the pneumoperitoneum, alternative methods of abdominal wall lifting have been explored recently. Most of these systems are complicated in their system set-up and handling or the intraabdominal exposure is limited. The modular retraction system (VarioLift, AESCULAP Tuttlingen) consists of two different components, one for the abdominal wall lifting, and one for internal organ compression. Via a 2 cm mini-laparotomy two lifting parts of different size and shape are introduced into the abdominal cavity, assembled to each other and attached to an outside mechanical lifting arm which is suspended to the operating table. Using combinations of these parts, the system can be adjusted to different abdominal quadrants and the patient's individual anatomy. According to the needs of vision for internal organ compression a translucent plastic membrane can be placed for posterior organ retraction using the same access. In contrast to other systems the modular retraction system (VarioLift) allows an individual adjustment to the patient's anatomy and, if necessary, compression of internal organs. A planar suspension of the abdominal wall with a good lateral exposure and a dome-shaped suspension without tenting effects is provided. Time needed for mini-laparotomy and system set-up is only slightly longer than installation of a pneumoperitoneum.

In vitro metabolism of aromatic nitriles

Studies on the metabolic fate of aromatic nitriles, in contrast to their aliphatic counterparts, have been minimal and the subject of controversy. The in vitro metabolic fate of several aromatic nitriles with varying substituents was investigated by using rat liver subcellular fractions, with a particular emphasis on the nitrile moiety. Benzonitriles and 4-cyanophenols underwent oxidative metabolism to produce ring-hydroxylated metabolites. On the other hand, 2-cyanophenol was resistant to metabolism. o-Tolunitrile was metabolized and produced o-cyanobenzyl alcohol and phthalide. Phthalide, however, was chemically derived from o-cyanobenzyl alcohol, the initial metabolite. 4-Nitrobenzonitrile was resistant to oxidation on the ring, but was readily reduced to the corresponding amine metabolite under both aerobic and anaerobic conditions. Nitroxynil (3-iodo-4-hydroxy-5-nitrobenzonitrile) was metabolized to produce 3-iodo-4-hydroxy-5-nitrobenzamide and 3-iodo-4-hydroxy-5-nitrobenzoic acid. The enzyme(s) responsible for this hydrolytic metabolism was primarily localized in the cytosol. Among the nitriles tested, o-tolunitrile and nitroxynil produced metabolites in which the nitrile moiety was modified. Nitroxynil, however, was the only compound that was directly metabolized on the nitrile moiety by the rat liver enzyme(s).

Antibody-mediated rejection of human orthotopic liver allografts. A study of liver transplantation across ABO blood group barriers

A clinicopathologic analysis of liver transplantation across major ABO blood group barriers was carried out 1) to determine if antibody-mediated (humoral) rejection was a cause of graft failure and if humoral rejection can be identified, 2) to propose criteria for establishing the diagnosis, and 3) to describe the clinical and pathological features of humoral rejection. A total of 51 (24 primary) ABO-incompatible (ABO-I) liver grafts were transplanted into 49 recipients. There was a 46% graft failure rate during the first 30 days for primary ABO-I grafts compared with an 11% graft failure rate for primary ABO compatible (ABO-C), crossmatch negative, age, sex and priority-matched control patients (P less than 0.02). A similarly high early graft failure rate (60%) was seen for nonprimary ABO-I grafts during the first 30 days. Clinically, the patients experienced a relentless rise in serum transaminases, hepatic failure, and coagulopathy during the first weeks after transplant. Pathologic examination of ABO-I grafts that failed early demonstrated widespread areas of geographic hemorrhagic necrosis with diffuse intraorgan coagulation. Prominent arterial deposition of antibody and complement components was demonstrated by immunoflourescent staining. Elution studies confirmed the presence of tissue-bound, donor-specific isoagglutinins within the grafts. No such deposition was seen in control cases. These studies confirm that antibody mediated rejection of the liver occurs and allows for the development of criteria for establishing the diagnosis.

Transplantation for primary biliary cirrhosis

Primary biliary cirrhosis is a frequent indication for liver transplantation. The purpose of this report is to present our experience with liver transplantation for primary biliary cirrhosis. Attention is given to the causes of hepatic dysfunction seen in allografts. In addition, we review the postoperative problems encountered and the quality of life at time of last follow-up in patients with transplants for primary biliary cirrhosis. A total of 97 orthotopic liver transplant procedures were performed in 76 patients with advanced primary biliary cirrhosis at the University of Pittsburgh from March 1980 through September 1985. The transplant operation was relatively easy to perform. The most common technical complications experienced were fragmentation and intramural dissection of the recipient hepatic artery, which required an arterial graft in 20% of the cases. Most of the postoperative mortality occurred in the first 6 mo after transplantation, with an essentially flat actuarial life survival curve from that time point to a projected 5-yr survival of 66%. Common causes of death included rejection and primary graft nonfunction. Thirteen of the 76 patients had some hepatic dysfunction at the time of the last follow-up, although none were jaundiced. Recurrence of primary biliary cirrhosis could not be demonstrated in any of the patients. Antimitochondrial antibody was detected in the serum of almost all of the patients studied postoperatively for it. Most important, almost all of the 52 surviving patients have been rehabilitated socially and vocationally.

[Measurement of depth dose curves of soft x-rays in a water phantom]

A device is described which allows to perform dosimetry with a usual flat chamber made of plexiglas (PTW soft ray chamber) in the water phantom. The depth dose curves measured for anode potentials of 10 to 100 kV were compared to the curves measured a) in a plexiglas phantom, b) in a M3 phantom using a soft ray chamber made of M3, c) in a mixed phantom consisting of a plexiglas bottom, a soft ray chamber made of plexiglas flush with its surface, and plates or foils made of M3, polystyrene, and frapan. The results show that there is no difference between the depth dose curves measured in water and those measured in the homogeneous M3 phantom if the curve is plotted over the mass related to the surface (g/cm2). There is also no difference to the dose curve measured in the mixed phantom according to c) if M3 plates determining the depth of measurement are layed on it. With the other substances, considerable deviations are found. An example is presented in order to warn against the uncontrolled use of "plastic foils" as phantom material for soft ray depth dose curves.

A liver transplant center information management system

A comprehensive microcomputer-based data management system has been developed to facilitate candidate selection and to track clinical performance for the liver transplant program at the University of Pittsburgh. A relational database manager, dedicated statistical analysis software, and presentation graphics are all elements that have been integrated into the system.

OKT3 in the reversal of acute hepatic allograft rejection

OKT3 was an effective immunosuppressant agent in patients with acute cell-mediated allograft rejection that had not responded to initial steroid therapy. OKT3 was also valuable for treating patients with early hepatic graft dysfunction caused by other factors than rejection. In such recipients, the doses of CyA can be greatly reduced, allowing recovery of frequently damaged kidneys while maintaining effective immunosuppression.

The antibody crossmatch in liver transplantation

Six hundred sixty-seven first, second, and third orthotopic liver allografts in 520 patients were reviewed to determine the effect of recipient panel-reactive antibody (PRA) and donor-recipient antibody crossmatch on 2-year patient and liver allograft survival rates. Neither a high panel-reactive antibody nor a positive crossmatch for donor-specific preformed antibody was associated with decreased patient or liver allograft survival for primary grafts or retransplants. Two patients have been given kidney transplants immediately after a liver allograft from a donor with whom each patient had an initial strongly positive donor-specific antibody crossmatch. The liver apparently removed or neutralized circulating anti-donor antibody, since the renal allografts functioned promptly and did not experience hyperacute rejection.

[Roentgen findings in gastroenterostomy]

Gastroenterostomy is a palliative operation for drainage. It can be represented by retrocolic and antecolic, isoperistaltic and anisoperistaltic, laterolateral and Y-Roux anastomosis. Impressions by the colic ligament are normal findings. pathological findings are anastomosis - obstruction, high position, ulcer, blind loops, gastroileostomy, volvulus of the anastomosed loop, herniation, invagination, and changes in the underlying disease.

Radiosensitivity of haematopoietic stem cells (DCPC and CFU-GM) from cord blood

The radiosensitivity of human cord blood haematopoietic stem cells was measured by assessing colony formation in methylcellulose cultures and diffusion chambers. The results show that fetal colony forming units, granulocytic, monocytic (CFU-GM), are radiosensitive: colonies formed by electron-irradiated CFU-GM, both in spontaneous and in colony stimulating factor (CSF) supplemented cultures decrease in number in an exponential fashion with increasing doses of irradiation. Do values up to 800 rads were, for highly purified fetal lymphoid cells, 160 +/- 88 rads; for whole buffy coat cells, 155 +/- 75 rads; and for buffy coat cells plus exogenous CSF: 155 +/- 77 rads. Extrapolation numbers (N) approached the value of 1. Among cord blood diffusion chambers progenitor cells (DCPC), radiosensitive and radioresistant subpopulations of myelopoietic stem cells exist, as tested over a range up to 1500 rads. Monocytopoietic CFU-D are radioresistant.

[Concept of the mean stopping power and the mean electron energy in electron dosimetry]

In consideration of the variations of the values E,Er,EH and Ew of the energy spectrum of electrons at the measuring point in case of a given energy on the surface Eo and in the depth t of a phantom with a low Z-number, the authors present the practical realisation of a conception allowing to determine by one single conversion curve Sw,1 (Er) the energy-dose of rapid electrons in water Dw, at least within the spectrum of Eo = 5 to 42 MeV and Er = 2.2 to 42 MeV, from the cavity ion dose Jc measured absolutely or by means of a calibrated electron chamber. Sw,1 (Er) is the relative unrestricted mass collision stopping power as a function of the mean rest energy Er at the measuring point. Er can be calculated in a simple manner from Eo and t and coincides almost perfectly with the most probable energy Ew of measured electron spectra. The authors present an algorithm for the calculation of the true mean electron energy E from Eo and t with a good coincidence with the values of measured electron spectra. It is shown that, contrary to the curve with one parameter Sw,1 (Er), a relation of Sw,1 to E leads to a series of curves with two parameters Sw,1 (Eo, t). The method using a relation of Sw,1 to Er which offers the advantage of a simple practical application and good precision is presented as "conception of the mean stopping power in electron dosimetry".

[Absolute ionization dosimetry of high energy electrons with an energy of more than 15 Mev]

By means of a graphite double extrapolation chamber, the self consistent dosimetry system already used for an electron energy until 15 MeV also allows an absolute determination of the cavity ion dose until 42 MeV which can be performed under practically ideal Bragg-Gray conditions with the precision of a primary standard. For the conversion into energy-dose, the relative mass collision stopping power sw,l reduced to the universal dosimetric constants W/e, G and epsilon is used which is determined by the system itself and corresponds to the theoretic relative unrestricted mass collision stopping power. A clear function for sw,l only depending on Er is achieved by a co-ordination with the mean rest energy of electrons Er, and that in any measuring depth. This function also harmonizes with the theoretical values of the relative unrestricted mass collision stopping power in the enlarged energy range. The performance specifications and influence quantities of the small parallel-plate chamber ("Electron Chamber") which also has been already used until 15 MeV as a secondary standard dosemeter and field instrument in the water, M3 or plexiglas phantom keep the same values and ranges of use. The calibration factor of the cavity ion dose is independent of the energy and remains constant also for the enlarged energy range. The measuring accuracy for the cavity ion dose and the energy-dose are unchanged.

[Different effectiveness of hyperthermia with regard to fast electrons and X-rays with different energy spectra (author's transl)]

The synergistic enhancement of the irradiation effect by mild (40.5 degrees C) and strong (43 degree C) hyperthermia (TER = temperature enhancement ratio) was examined for different sparsely ionizing radiation qualities (15 meV electrons in two irradiation depths corresponding to a relative depth dose of 100% and 30%, 200-kV and 29-kV-X-rays). Hypotetraploid ("4n") and diploid (2n), asynchronous, exponentially growing CHO fibroblasts were used as experimental subjects. The survival inthe colony test was used as criterion to assess the effect. The experiments carried out with 4n cells showed that, for the two temperatures, the TER decreases with increasing ionization density and, when applying fast electrons producing an extremely sparse ionization in an irradiation depth of 100%, the TER shows a maximum increase as compared to the more densely ionizing radiation qualities. Already when mild hyperthermia is employed, fast electrons show a TER of 1.25 which rises to about 2.25 at 43 degrees C. In case of 29-kV-X-rays, these values amount to 1 and 1.66 respectively. As to the 2n cells, the TER reaches here the double value and seems to be similarly dependent on the ionization density.

[A simple formula for determination of the mean electron energy in a body irradiated by fast electrons (author's transl)]

A simple formula for calculation of the mean electron energy from primary energy and depth of irradiation is derived. The formula has been verified for substances with low atomic numbers (Z less than or equal to 6) and by experiments using primary electron energies from 5 to 15 MeV and irradiation depths up to 80% of the practical range, which corresponds to mean electron energies from 2.2 to 15 MeV. For this purpose, the relative mass stopping-power ratios water/air which have been obtained using the formula together with valid standard tables (ICRU, DIN) and literature were compared with those found by absolute dosimetry by means of a graphite double extrapolation chamber (primary standard). An optimal accordance with the standard values for non-restricted mass collision stopping-power, as indicated by Berger and Seltzer, was the result (better than +0.6 to -0.05%). The verification of a formula known from literature (Harder) revealed similar results (+0.4 to -0.8%).

[A review of 25 years' clinical application of fast electrons in radiation therapy (author's transl)]

The first betatron developed for current use of fast electrons in radiation therapy (15 MeV, Siemens) has been installed at the Dermatologische Klinik der Universität Göttingen in 1952 (Bode, Markus). The first human carcinoma treated with fast electrons was irradiated using the first 6-MeV-betatron (Dr. Gund, Siemens) at the 2nd institute of physics of the Göttingen university (Bode, Kopfermann, Paul, 1949). Characteristics of the electron radiation utilized for treatment and its particular advantages in dermatological radation therapy are reported. Two clinical examples, one of them the first human carcinoma irradiated with fast electrons, are described, and the frequency distribution of the indications for electron therapy at the dermatological clinics of the university is tabulated for a total of 3419 cases treated between 1949 and 1972 (Bode et al.).

[A parallel-plate small volume chamber for dosimetry of fast electrons and its use]

The ionization chamber described is designed for dosimetry of electron radiation above ca. 100 keV. It is used for the measurement of the cavity ion dose and of the absorbed dose within solid or water phantoms. Its construction corresponds to a flat chamber in accordance with DIN 6800. The cylindric main body is made of plexiglass (diameter 30 mm, height 14 mm) and encompasses the measuring volume being flush with the surface (diameter 5 mm, height 2 mm; chamber window 2.3 mg/cm2; build up cap for measurements in water 236 mg/cm2). The chamber is constructed with regard to its independency on energy and direction of the incidence as well as to the minimization of the remaining influence quantities, thus answering for the accuracy class "reference-class instrument" (+/- 0.5%). The polarity effect and field perturbation effect are to be neglected, the displacement comes to 0.1 mm, the statistical inaccuracy of measurement to 0.1%. The calibration for the chamber was obtained with a 15 MeV electron beam. The calibration factor for the cavity ion dose is constant, not being related to energy, at least in the range of performance from 2 to 15 MeV according to the primary standard used for calibration (graphic double extrapolation chamber). The overall uncertainty of the calibration factor amounts to +/- 1.5% for the cavity ion dose and to +/- 1.8% for the energy dose. Numerical values of all characteristic quantities and influence quantities which correspond to DIN 6817 and also measurement results for the determination of dose and energy are reported.

[A polarization effect-free graphite double extrapolation chamber for the absolute dosimtery of high energy electrons]

Theoretical principles, constructional features and operation of an improved extrapolation-chamber intended for absolute ionization dosimetry of high-energy electrons are described. The construction allows a precise variation of the cylindrical measuring volume by varying thickness and diameter (exactly from 0 to 30 or 3 to 30 mm resp.), whereat measurements can be taken either using cylindrical graphitic walls or "no walls". The improvements consist in a combination of the following characteristics: high electric and mechanical stability; avoidance of disturbances due to electrostatic charges; elimination of the polarity error; practically homogeneous graphitic construction without foreign materials; graphite as a preferential reference material; measurements by chemical dosimetry following within the same apparatus. Results of measurements are reported concerning the verification of the complete or partial equilibrium of electrons, the deviations from the ideal cavity conditions of Bragg and Gray, and the comparison with ferrous sulfate dosimetry. Absolute measurements of the ion dose being accurate to about 0.5% can be obtained with the chamber. Thus, the chamber seems qualified to be used as a primary standard.