Modeling the global fate and transport of perfluorooctane sulfonate (PFOS) and precursor compounds in relation to temporal trends in wildlife exposure

A global-scale fate and transport model was applied to investigate the historic and future trends in ambient concentrations of perfluorooctane sulfonate (PFOS) and volatile perfluorooctane sulfonyl fluoride (POSF)-based precursor compounds in the environment. First, a global emission inventory for PFOS and its precursor compounds was estimated for the period 1957-2010. We used this inventory as input to a global-scale contaminant fate model and compared modeled concentrations with field data. The main focus of the simulations was to examine how modeled concentrations of PFOS and volatile precursor compounds respond to the major production phase-out that occurred in 2000-2002. Modeled concentrations of PFOS in surface ocean waters are generally within a factor of 5 of field data and are dominated by direct emissions of this substance. In contrast, modeled concentrations of the precursor compounds considered in this study are lower than measured concentrations both before and after the production phase-out. Modeled surface ocean water concentrations of PFOS in source regions decline slowly in response to the production phase-out while concentrations in remote regions continue to increase until 2030. In contrast, modeled concentrations of precursor compounds in both the atmosphere and surface ocean water compartment in all regions respond rapidly to the production phase-out (i.e., decline quickly to much lower levels). With respect to wildlife biomonitoring data, since precursor compounds are bioavailable and degrade to PFOS in vivo, it is at least plausible that declining trends in PFOS body burdens observed in some marine organisms are attributable to this exposure pathway. The continued increases in PFOS body burdens observed in marine organisms inhabiting other regions may reflect exposure primarily to PFOS itself, present in the environment due to production and use of this compound as well as degradation of precursor compounds.

Comparative assessment of the global fate and transport pathways of long-chain perfluorocarboxylic acids (PFCAs) and perfluorocarboxylates (PFCs) emitted from direct sources

A global-scale multispecies mass balance model was used to simulate the long-term fate and transport of perfluorocarboxylic acids (PFCAs) with eight to thirteen carbons (C8-C13) and their conjugate bases, the perfluorocarboxylates (PFCs). The main purpose of this study was to assess the relative long-range transport (LRT) potential of each conjugate pair, collectively termed PFC(A)s, considering emissions from direct sources (i.e., manufacturing and use) only. Overall LRT potential (atmospheric + oceanic) varied as a function of chain length and depended on assumptions regarding pKa and mode of entry. Atmospheric transport makes a relatively higher contribution to overall LRT potential for PFC(A)s with longer chain length, which reflects the increasing trend in the air-water partition coefficient (K(AW)) of the neutral PFCA species with chain length. Model scenarios using estimated direct emissions of the C8, C9, and C11 PFC(A)s indicate that the mass fluxes to the Arctic marine environment associated with oceanic transport are in excess of mass fluxes from indirect sources (i.e., atmospheric transport of precursor substances such as fluorotelomer alcohols and subsequent degradation to PFCAs). Modeled concentrations of C8 and C9 in the abiotic environment are broadly consistent with available monitoring data in surface ocean waters. Furthermore, the modeled concentration ratios of C8 to C9 are reconcilable with the homologue pattern frequently observed in biota, assuming a positive correlation between bioaccumulation potential and chain length. Modeled concentration ratios of C11 to C10 are more difficult to reconcile with monitoring data in both source and remote regions. Our model results for C11 and C10 therefore imply that either (i) indirect sources are dominant or (ii) estimates of direct emission are not accurate for these homologues.

A model assessment of polychlorinated dibenzo-p-dioxin and dibenzofuran sources and fate in the Baltic Sea

The contamination of the Baltic Sea with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) has resulted in restrictions on the marketing and consumption of Baltic Sea fish, making this a priority environmental issue in the European Union. To date there is no consensus on the relative importance of different sources of PCDD/Fs to the Baltic Sea, and hence no consensus on how to address this issue. In this work we synthesized the available information to create a PCDD/F budget for the Baltic Sea, focusing on the two largest basins, the Bothnian Sea and the Baltic Proper. The non-steady state multimedia fate and transport model POPCYCLING-Baltic was employed, using recent data for PCDD/F concentrations in air and sediment as boundary conditions. The PCDD/F concentrations in water predicted by the model were in good agreement with recent measurements. The budget demonstrated that atmospheric deposition was the dominant source of PCDD/Fs to the basins as a whole. This conclusion was supported by a statistical comparison of the PCDD/F congener patterns in surface sediments from accumulation bottoms with the patterns in ambient air, bulk atmospheric deposition, and a range of potential industrial sources. Prospective model simulations indicated that the PCDD/F concentrations in the water column will continue to decrease in the coming years due to the slow response of the Baltic Sea system to falling PCDD/F inputs in the last decades, but that the decrease would be more pronounced if ambient air concentrations were to drop further in the future, for instance as a result of reduced emissions. The study illustrates the usefulness of using monitoring data and multimedia models in an integrated fashion to address complex organic contaminant issues.

Modeling the global fate and transport of perfluorooctanoic acid (PFOA) and perfluorooctanoate (PFO) emitted from direct sources using a multispecies mass balance model

The global-scale fate and transport processes of perfluorooctanoic acid (PFOA) and perfluorooctanoate (PFO) emitted from direct sources were simulated using a multispecies mass balance model over the period 1950 to 2010. The main goal of this study was to assess the atmospheric and oceanic long-range transport potential of direct source emissions and the implications for the contamination of terrestrial and marine systems worldwide. Consistent with previous modeling studies, ocean transport was found to be the dominant pathway for delivering PFO(A) associated with direct sources to the Arctic marine environment regardless of model assumptions. The modeled concentrations for surface ocean waters were insensitive to assumptions regarding physical-chemical properties and emission mode of entry and were in reasonable agreement with available monitoring data from the Northern Hemisphere. In contrast, model outputs characterizing atmospheric transport potential were highly sensitive to model assumptions, especiallythe assumed value of the acid dissociation constant (pKa). However, the complete range of model results for scenarios with different assumptions about partitioning and emissions provide evidence that the atmospheric transport of directly emitted PFO(A) can deliver this substance to terrestrial environments distant from sources. Additional studies in remote or isolated terrestrial systems may provide further insight into the scale of contamination actually attributable to direct sources.

Modeling the global fate and transport of perfluorooctanoic acid (PFOA) and perfluorooctanoate (PFO) emitted from direct sources using a multispecies mass balance model

The global-scale fate and transport processes of perfluorooctanoic acid (PFOA) and perfluorooctanoate (PFO) emitted from direct sources were simulated using a multispecies mass balance model over the period 1950 to 2010. The main goal of this study was to assess the atmospheric and oceanic long-range transport potential of direct source emissions and the implications for the contamination of terrestrial and marine systems worldwide. Consistent with previous modeling studies, ocean transport was found to be the dominant pathway for delivering PFO(A) associated with direct sources to the Arctic marine environment regardless of model assumptions. The modeled concentrations for surface ocean waters were insensitive to assumptions regarding physical-chemical properties and emission mode of entry and were in reasonable agreement with available monitoring data from the Northern Hemisphere. In contrast, model outputs characterizing atmospheric transport potential were highly sensitive to model assumptions, especiallythe assumed value of the acid dissociation constant (pKa). However, the complete range of model results for scenarios with different assumptions about partitioning and emissions provide evidence that the atmospheric transport of directly emitted PFO(A) can deliver this substance to terrestrial environments distant from sources. Additional studies in remote or isolated terrestrial systems may provide further insight into the scale of contamination actually attributable to direct sources.

Estimated 10-year cardiovascular risk in a British population: results of a national screening project

OBJECTIVE

To estimate 10-year cardiovascular disease (CVD) risk using the risk equation and risk categories of the Joint British Societies' Guidelines on Prevention of Cardiovascular Disease in Clinical Practice (2005).

METHODS

A cross-sectional CVD screening programme was conducted in 35 towns in Great Britain. In total, 27,776 men and 43,261 women aged at least 18 years were screened. The estimated 10-year risk of CVD was calculated and directly standardised to the population of Great Britain.

RESULTS

The age standardised combined prevalence of known CVD, diabetes, lipid-lowering or antihypertensive drug therapy, which preclude multifactorial risk assessment, was 18.0% for men and 18.1% for women. CVD risk was calculated for 56,863 individuals, and the age-standardised prevalence of an estimated 10-year CVD risk < 10% was 42.7% (95% CI: 42.2-43.1) for men and 60.4% (95% CI: 60.1-60.7) for women; 10% to < 20% was 19.6% (19.1-20.6) and 15.6% (15.2-15.9); and > or = 20% was 19.6% (19.1-20.0) and 6.0% (5.8-6.2) respectively. After aggregating known CVD, diabetes, antihypertensive or lipid-lowering drug therapy, or an estimated CVD risk of > or = 20%, the combined standardised prevalence of high CVD risk for individuals aged 50 years or more was 74.1% (73.5-74.8) for men (n = 14,787) and 45.5% (44.8-46.2) for women (n = 24,400).

CONCLUSIONS

Using current risk thresholds, there is a substantial unmet need for primary prevention of CVD, particularly among middle-aged men. The results emphasise the scale of intervention that a strategy of individual risk assessment and pharmacological intervention requires.

Modeling the potential influence of particle deposition on the accumulation of organic contaminants by submerged aquatic vegetation

Submerged aquatic vegetation can act as both a mitigating factor(e.g., reducing downstream impacts of pesticides following runoff/spray drift) and mobilizing factor (e.g., remobilization of contaminants from sediments) influencing the fate and distribution of organic contaminants in the environment. Consequently, there has been wide scientific and regulatory interest in assessing the role of these plants in different contamination scenarios. Mechanistic models describing the environmental fate of contaminants in submerged aquatic vegetation are useful tools for interpreting laboratory and field measurements in addition to providing valuable information to risk assessors. In this study, we developed a fugacity-based model to investigate the influence of particle deposition to plant surfaces on the fate and distribution of two substances in small ponds. The main motivation for conducting this study was to address the fact that the potential contribution of this process is not typically considered by many types of models describing contaminant dynamics in submerged aquatic vegetation. For the hydrophobic substance included in this evaluation (lambda-cyhalothrin), model performance was greatly improved by including this process. The model was also applied in a generic context to compare the importance of particle deposition versus directwater uptake as a function of chemical properties (log Kow) and concentration of suspended solids in the water column. The generic application demonstrated that contaminant mass transfer is dominated by particle deposition for chemicals with log Kow greater than approximately 5.5--6 across a wide range of suspended solid concentrations and can be important even for low log Kow substances in some circumstances. Further empirical and modeling studies are recommended to explore this process more comprehensively.

Model and input uncertainty in multi-media fate modeling: benzo[a]pyrene concentrations in Europe

This paper evaluates the contribution of (i) uncertainty in substance properties, (ii) lack of spatial variability, (iii) intermodel differences and (iv) neglecting sorption to black carbon (BC) to the uncertainty of Benzo[a]pyrene (BaP) concentrations in European air, soil and fresh water predicted by the multi-media fate model Simplebox. Uncertainty in substance properties was quantified using probabilistic modeling. The influence of spatial variability was quantified by estimating variation in predicted concentrations with three spatially explicit fate models (Impact 2002, EVn BETR and BETR Global). Intermodel differences were quantified by comparing concentration estimates of Simplebox, Impact 2002, EVn BETR and the European part of BETR Global. Finally, predictions of a BC-inclusive version of Simplebox were compared with predictions of a BC-exclusive version. For air concentrations of BaP, the lack of spatial variability in emissions was most influential. For freshwater concentrations of BaP, intermodel differences and lack of spatial variability in dimensions of fresh water bodies were the dominant sources of uncertainty. For soil, all sources of uncertainty were of comparable magnitude. Our results indicate that uncertainty in Simplebox can be as large as three orders of magnitude for BaP concentrations in the environment and would be substantially underestimated by focusing on one source of uncertainty only.

Black carbon-inclusive modeling approaches for estimating the aquatic fate of dibenzo-p-dioxins and dibenzofurans

A novel black carbon (BC) inclusive modeling tool is applied to estimate the distribution and long-term fate of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Norwegian Grenland Fjords. Three versions of the model were developed in which sediment-water partitioning was described using (i) an amorphous organic carbon (AOC) partitioning sorption model without BC sorption, (ii) a combined AOC and BC sorption model based on the Freundlich isotherm, and (iii) a combined BC-AOC model based on the Langmuir isotherm. The predictive ability of the three different models was evaluated for 17 PCDD/Fs by comparison of model predictions with observed organic carbon normalized sediment-water partition coefficients (K(TOC)) and with measured concentrations. All three versions of the model were able to predict concentrations that were in reasonable agreement with measured particulate concentrations (i.e., within a factor of 4 of median values). Estimated particulate concentrations were less sensitive to the model choice because the majority of the mass of these hydrophobic chemicals is associated with particulates regardless. However, for estimation of K(TOC) or dissolved water concentrations, both versions of the combined AOC and BC sorption models provided greatly improved estimates compared to the AOC-only model.

Modeling the effects and uncertainties of contaminated sediment remediation scenarios in a Norwegian fjord by Markov chain Monte Carlo simulation

Multimedia environmental fate models are useful tools to investigate the long-term impacts of remediation measures designed to alleviate potential ecological and human health concerns in contaminated areas. Estimating and communicating the uncertainties associated with the model simulations is a critical task for demonstrating the transparency and reliability of the results. The Extended Fourier Amplitude Sensitivity Test(Extended FAST) method for sensitivity analysis and Bayesian Markov chain Monte Carlo (MCMC) method for uncertainty analysis and model calibration have several advantages over methods typically applied for multimedia environmental fate models. Most importantly, the simulation results and their uncertainties can be anchored to the available observations and their uncertainties. We apply these techniques for simulating the historical fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Grenland fjords, Norway, and for predicting the effects of different contaminated sediment remediation (capping) scenarios on the future levels of PCDD/Fs in cod and crab therein. The remediation scenario simulations show that a significant remediation effect can first be seen when significant portions of the contaminated sediment areas are cleaned up, and that increase in capping area leads to both earlier achievement of good fjord status and narrower uncertainty in the predicted timing for this.

A terrestrial food-chain bioaccumulation model for POPs

Mechanistic bioaccumulation models for fish and piscivorous food-webs are widely used to assess the environmental hazard and risk of commercial chemicals, develop water quality criteria and remediation objectives, and conduct exposure assessment of pesticides in aquatic systems. Similar models for mammals and terrestrial food-webs are largely absent. As a result, the hazards and risks of bioaccumulative substances in mammals, birds, and humans remain unrecognized by regulators, and current globally used criteria for identifying bioaccumulative substances only apply to water-breathing organisms and are inadequate for protecting air-breathing organisms including mammals, birds, and human beings. In this paper, we develop and test a modeling framework that can be used to estimate the biomagnification potential and the organism-soil bioaccumulation factor of organic commercial chemicals in terrestrial food-chains. We test the model for the soil-earthworm-shrew food-chain and apply the model to illustrate that (i) chemicals with an octanol-air partition coefficient (K(OA)) < 10(5.25) do not biomagnify even if the K(ow) is high and optimal for biomagnification in fish; (ii) chemicals with a K(OA) > or = 105.25 and a K(ow) between 10(1.75) and 10(12) have a biomagnification potential unless they are metabolized at a sufficiently rapid rate (e.g., in excess of 0.3 d(-1) or a half-life time of 2.5 d for shrews).

Empirical evaluation of spatial and non-spatial European-scale multimedia fate models: results and implications for chemical risk assessment

Multimedia environmental fate models are commonly-applied tools for assessing the fate and distribution of contaminants in the environment. Owing to the large number of chemicals in use and the paucity of monitoring data, such models are often adopted as part of decision-support systems for chemical risk assessment. The purpose of this study was to evaluate the performance of three multimedia environmental fate models (spatially- and non-spatially-explicit) at a European scale. The assessment was conducted for four polycyclic aromatic hydrocarbons (PAHs) and hexachlorobenzene (HCB) and compared predicted and median observed concentrations using monitoring data collected for air, water, sediments and soils. Model performance in the air compartment was reasonable for all models included in the evaluation exercise as predicted concentrations were typically within a factor of 3 of the median observed concentrations. Furthermore, there was good correspondence between predictions and observations in regions that had elevated median observed concentrations for both spatially-explicit models. On the other hand, all three models consistently underestimated median observed concentrations in sediment and soil by 1-3 orders of magnitude. Although regions with elevated median observed concentrations in these environmental media were broadly identified by the spatially-explicit models, the magnitude of the discrepancy between predicted and median observed concentrations is of concern in the context of chemical risk assessment. These results were discussed in terms of factors influencing model performance such as the steady-state assumption, inaccuracies in emission estimates and the representativeness of monitoring data.

Levels and vertical distribution of PCBs in agricultural and natural soils from Sweden

Soils represent an important reservoir for persistent organic pollutants (POPs) in the terrestrial environment and thus the fate of contaminants deposited to the surface soils is important to understand. Since only a limited number of studies of the vertical distribution of POPs are available in the literature, the purpose of this study was to collect and analyze PCB concentrations in different layers of soil cores taken at agricultural and non-agricultural sites in Sweden. PCB concentrations at the agricultural site were nearly uniform on a dry weight basis throughout the depth considered (0-12 cm) while a distinct gradient with depth was observed at the five non-agricultural sites. On an organic carbon normalized basis, the concentration gradient was maintained at three of the non-agricultural sites while a more uniform distribution was observed at the other two sites. A statistically significant relationship between dry weight soil concentrations and organic carbon content was determined for all PCB congeners in the surface layers (0-1 cm) but not in the deeper layers (4-5 cm, 9-10 cm). These results were interpreted in relation to vertical soil transport processes and then the implications for environmental fate models including soil compartments were discussed.

Systematic review of dietary intervention trials to lower blood total cholesterol in free-living subjects

OBJECTIVES

To estimate the efficacy of dietary advice to lower blood total cholesterol concentration in free-living subjects and to investigate the efficacy of different dietary recommendations.

DESIGN

Systematic overview of 19 randomised controlled trials including 28 comparisons.

SUBJECTS

Free-living subjects.

INTERVENTIONS

Individualised dietary advice to modify fat intake.

MAIN OUTCOME MEASURE

Percentage difference in blood total cholesterol concentration between the intervention and control groups.

RESULTS

The percentage reduction in blood total cholesterol attributable to dietary advice after at least six months of intervention was 5.3% (95% confidence interval 4.7% to 5.9%). Including both short and long duration studies, the effect was 8.5% at 3 months and 5.5% at 12 months. Diets equivalent to the step 2 diet of the American Heart Association were of similar efficacy to diets that aimed to lower total fat intake or to raise the polyunsaturated to saturated fatty acid ratio. These diets were moderately more effective than the step 1 diet of the American Heart Association (6.1% v 3.0% reduction in blood total cholesterol concentration; P<0.0001). On the basis of reported food intake, the targets for dietary change were seldom achieved. The observed reductions in blood total cholesterol concentrations in the individual trials were consistent with those predicted from dietary intake on the basis of the Keys equation.

CONCLUSIONS

Individualised dietary advice for reducing cholesterol concentration is modestly effective in free-living subjects. More intensive diets achieve a greater reduction in serum cholesterol concentration. Failure to comply fully with dietary recommendations is the likely explanation for this limited efficacy.

Airway function tests and vocal cord paralysis in lung transplant recipients

Maximum expiratory and inspiratory flow-volume (MEFV, MIFV) curves, specific airway conductance (sGaw), and flexible fiberoptic laryngoscopy were examined in 8 pediatric lung transplant recipients with vocal cord paralysis (VCP). Six were heart-lung (H-L) and 2 double-lung (D-L) recipients, 7 had left VCP, and 1 had right VCP. Based on the pulmonary function tests (PFT), 2 subgroups could be distinguished in the 8 recipients with VCP. Group A (5/8 recipients; mean age, 13 +/- 3.4 years; mean height, 144.3 +/- 12.3 cm) had significantly reduced specific airway conductance (sGaw; < 2 SD from predicted) and normal MEF25, MEF50, peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV1), and %FEV1/forced vital capacity (FVC); this pattern suggested variable extrathoracic airway obstruction. PIF was normal in 4/5 and reduced in 1/5 of these recipients. Group B (3/8 recipients with VCP; mean age, 17 +/- 2.4 years; mean height, 156.3 +/- 12.0 cm) had significantly reduced sGaw, MEF25, MEF50, PEF, FEV1, and %FEV1/FVC, implying primarily small airway obstruction. These recipients had bronchiolitis obliterans. The results suggest that a pattern of reduced sGaw and normal MEFs, PEF, FEV1, and PIF should raise the possibility of VCP in patients after lung transplantation. sGaw is more sensitive than PIF and PEF in identifying airway obstruction due to VCP, and should be routinely included in the follow-up evaluation of lung transplant recipients.

Randomized placebo-controlled study of the effects of simvastatin on haemostatic variables, lipoproteins and free fatty acids. The Oxford Cholesterol Study Group

The Oxford Cholesterol Study is a randomized placebo-controlled trial designed primarily to assess the effects of simvastatin on blood cholesterol levels and side-effects in preparation for a large, long-term trial of the effects of cholesterol-lowering drug therapy on mortality. At present there is only limited evidence from randomized comparisons of the effects of HMG-CoA reductase inhibitors, such as simvastatin, on thrombogenic, as distinct from atherogenic, pathways in coronary heart disease. The present sub-study was carried out to assess the effects of simvastatin on a range of haemostatic variables, as well as on free fatty acids and on lipoprotein fractions not studied in detail previously. At an average of about 2 years after starting study treatment, non-fasting blood samples were obtained from a sequential sample of 162 participants who had been randomly allocated to receive 40 mg (54 patients) or 20 mg (57 patients) daily simvastatin or matching placebo treatment (51 patients). Only patients who reported taking their study treatment and who were not known to be diabetic or to be taking some other lipid lowering treatment were to be included. The principal comparisons were to be of those allocated simvastatin (i.e. 20 and 40 mg doses combined) vs those allocated placebo. Among patients allocated simvastatin, marginally significant lower factor VII antigen levels (12.10% +/- 6.08 of standard; 2P < 0.05) and non-significantly lower factor VII coagulant activity (8.24% +/- 4.99 of standard) and fibrinogen concentrations (0.10 +/- 0.08 g. l-1) were observed. In contrast, plasminogen activator inhibitor activity was significantly higher (2.62 +/- 1.03 IU; 2P < 0.01) among patients allocated simvastatin. No significant differences were seen in the other haemostatic factors studied (e.g. prothrombin fragment 1.2, factor XII and C1 inhibitor). Total free fatty acid concentration was marginally significantly reduced (2P = 0.02) with simvastatin, but none of the reductions in individual free fatty acids was significant. Lipoprotein fractions were only measured among patients allocated 40 mg daily simvastatin or placebo. Compared with placebo, simvastatin produced significant decreases not only in LDL cholesterol (1.74 +/- 0.15 mmol.1(-1): 2P < 0.0001) but also in VLDL cholesterol (0.28 +/- 0.08 mmol.1(-1); 2P < 0.001) and IDL cholesterol (0.17 +/- 0.03 mmol.1(-1); 2P < 0.0001). There were also lower triglyceride levels associated with LDL (0.07 +/- 0.01 mmol.1(-1); 2P < 0.0001), IDL (0.03 +/- 0.01 mmol.1(-1); 2P < 0.01) and VLDL (0.27 +/- 0.14; 2P = 0.05). The effects of simvastatin on haemostatic variables appear to be far less marked than its lipid effects. Given the associations of haemostatic factors with coronary heart disease incidence, larger randomized comparisons of the HMG-CoA reductase inhibitors (and of the newer fibrates which may produce greater effects) are needed to provide more reliable estimates of the extent to which they influence these variables.

Absence of effects of prolonged simvastatin therapy on nocturnal sleep in a large randomized placebo-controlled study. Oxford Cholesterol Study Group

1. It has been suggested that lipophilic HMG CoA reductase inhibitors, like lovastatin and simvastatin, may cause sleep disturbance. 2. Six hundred and twenty-one patients at increased risk of coronary heart disease were randomized in a single centre to receive 40 mg daily simvastatin, 20 mg daily simvastatin or matching placebo. To assess the effects of prolonged use of simvastatin on nocturnal sleep quality and duration, a sleep questionnaire was administered to 567 patients (95% of 595 survivors) at an average of 88 weeks (range: 44-129 weeks) after randomization. 3. The main outcome measures were sleep-related problems and use of sleep-enhancing medications reported during routine study follow-up visits, and responses to the sleep questionnaire about changes in sleep duration and about various sleep events during the preceding month. 4. No differences were observed between the treatment groups in the frequency of sleep-related problems reported, in the proportion of follow-up visits at which such problems were reported, or in the use of sleep-enhancing medications. The numbers who stopped study treatment were similar in the different treatment groups, and no patient stopped principally because of insomnia. In response to the sleep questionnaire, there were no significant differences between the treatment groups in reports of various sleep events during the preceding month, except that slightly fewer patients allocated simvastatin reported waking often. No differences in sleep duration were observed. 5. This placebo-controlled trial does not indicate any adverse effects of prolonged treatment with simvastatin on systematically sought measures of sleep disturbance.

Interferon-alpha affects the immune response in post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD) is associated with Epstein-Barr virus (EBV) and characterized by fever, lymphadenopathy, and graft dysfunction. We describe the clinical course of an EBV seronegative 11-yr-old boy who underwent double lung transplantation and subsequently developed PTLD in the graft. A reduction in immunosuppression and the addition of acyclovir did not result in improvement. Treatment with interferon-alpha (IFN-alpha), however, led to dramatic clinical, radiographic, and histologic improvement. Semiquantitative measurements of cytokine mRNA in his bronchoalveolar lavage cells prior to therapy with IFN-alpha revealed high levels of IL-4 and IL-10 mRNA, which decreased significantly with treatment. We speculate that the beneficial effect of IFN-alpha in the treatment of PTLD is directly related to the inhibition of type 2 helper (Th2-like) T-cells.

Absence of effect of simvastatin on the progression of lens opacities in a randomised placebo controlled study. Oxford Cholesterol Study Group

AIMS

A detailed assessment of ophthalmic effects of an HMG CoA reductase inhibitor, simvastatin, was performed.

METHODS

Six hundred and twenty one individuals considered to be at increased risk of coronary heart disease were randomised, following an 8 week placebo 'run in' period, to receive 40 mg daily simvastatin, 20 mg daily simvastatin, or matching placebo. Patients with a baseline corrected visual acuity better than 6/24 and without a history of cataract were eligible for detailed ophthalmic assessment at 6 months (539 patients assessed) and at 18 months (474 patients assessed).

RESULTS

No significant differences between the treatment groups were detected at the 6 month or 18 month visit in the refractive condition of the eye or in the mean intraocular pressure. Nor were there clear differences in the Oxford grading system scores for various measures of the major types of cataract (cortical spokes, posterior subcapsular cataract, nuclear brunescence, white scatter) or for other morphological features visible within the lens (fibre folds or focal dots). Scheimpflug slit image photographs and retroillumination analysis of the percentage of cataract within a defined region of the lens were also performed at each visit, with no clear differences observed between the treatment groups.

CONCLUSION

This single centre double blind study found no good evidence of any adverse effects of 18 months of simvastatin treatment on lens opacity formation, using a variety of validated techniques to assess cataract development. Routine clinic follow up of visual symptoms and admission to hospital for ophthalmic procedures over 5 years of treatment was also reassuring, with no excess adverse outcomes observed with simvastatin.

Comparison of outcomes after single and bilateral lung transplantation for obstructive lung disease

BACKGROUND AND METHODS

To determine the long-term functional outcome for single versus bilateral lung transplant for nonseptic obstructive lung disease, we compared the results from 39 single and nine bilateral lung transplant procedures. The nine bilateral lung transplants included three en bloc double lung and six bilateral sequential lung transplants.

RESULTS

Early deaths within 30 days of transplantation occurred in two of nine (22%) bilateral and 4 of 39 (10%) single lung transplants (p = Not significant). Compared with pretransplant values, pulmonary function as assessed by the spirometric indexes of the percent predicted forced vital capacity, forced expiratory volume in one second, forced expiratory volume in one second/forced vital capacity, and forced expiratory flow at 25% and 75% of forced vital capacity improved significantly up to at least 12 months after transplantation for both single and bilateral lung transplant recipients. The degree of pulmonary function improvement was better in single as compared with bilateral lung recipients. By 6 months after transplantation, all but one single and all bilateral lung recipients were in New York Heart Association class I or II (p = Not significant). One-year survival was significantly better after single (77%) compared with after bilateral lung transplantation (35%) (p < 0.05).

CONCLUSIONS

These results suggest that single lung transplantation is the procedure of choice for patients with nonseptic obstructive lung disease.

Exercise testing in pediatric heart, heart-lung, and lung transplant recipients

Cardiorespiratory responses to progressive exercise were examined in 38 children who had undergone heart (n = 16), heart-lung (n = 13), or double-lung (n = 9) transplantation, and in 41 healthy controls. The four groups were similar in age, but the control subjects and heart transplant recipients were significantly larger than the heart-lung and lung recipients as assessed by body mass index (BMI). Time since transplant was significantly longer in the heart (601 days) compared with heart-lung (146 days) and lung (125 days) transplant groups. Physical work capacity and peak oxygen uptake were significantly reduced (43 to 64% of predicted) in the three transplant groups compared with the control group. Peak heart rate (percent predicted) was significantly higher in the control subjects (94%) compared with the heart (66%), heart-lung (70%), and lung (77%) transplant recipients. Peak minute ventilation was significantly higher in the control (72.9 L/min) and heart transplant (51.0 L/min) groups than the heart-lung (37.4 L/min) and lung (41.3 L/min) transplant groups. The control group had a higher peak tidal volume than the three transplant groups, and a higher peak respiratory rate than the lung transplant recipients. Correlational analysis revealed that physical work capacity (PWC) was significantly related to heart rate at peak exercise (HRpeak) and minute ventilation at peak exercise (VE-peak) in the heart transplant recipients, BMI, VEpeak, and FEV1 in the heart-lung transplant recipients, and BMI, HRpeak, VEpeak, FEV1, and number of days posttransplant in the lung transplant recipients. In addition to these variables, physical deconditioning and factors related to pharmacotherapy, infection, and rejection may also contribute to the decreased PWC observed in the transplant recipients.

Immunosuppression switch in pediatric heart transplant recipients: cyclosporine to FK 506

OBJECTIVES

We studied rejection, allograft function and side effects, such as hypertension, renal dysfunction and hypercholesterolemia, in seven patients switched from cyclosporine-based triple-drug immunosuppression to FK 506.

BACKGROUND

A subset of pediatric heart transplant recipients treated with triple-drug immunosuppression consisting of cyclosporine, azathioprine and prednisone experience either persistent rejection when attempts are made to taper corticosteroids or morbidity from cyclosporine and corticosteroids. Experience with the new immunosuppressive agent FK 506 has demonstrated its effectiveness as a single agent in heart transplant recipients, and anecdotal evidence has shown that side effects such as hypertension and hypercholesterolemia may be lower.

METHODS

Seven patients whom we deemed corticosteroid dependent were switched to FK 506-based therapy. Allograft function, episodes of rejection, need for corticosteroids and incidence of side effects from FK 506 were monitored. The switch to FK 506 was performed using an established protocol. Follow-up time has ranged from 15 to 41 months. Serial right heart catheterizations and endomyocardial biopsies were performed after each reduction of corticosteroid dosing.

RESULTS

Catheterization data showed no significant change in pulmonary wedge pressure, mean right atrial pressure or cardiac index, indicating no decline in allograft function. Serial echocardiographic variables of allograft function were also stable. At present, all seven patients are free of the corticosteroid portion of their immune suppression. There have been only two episodes of significant acute rejection requiring treatment with intravenous corticosteroids. Antihypertensive medications have been discontinued in five of six patients previously treated with these drugs. Plasma cholesterol, low density lipoprotein and triglyceride levels were decreased, and renal function was stable.

CONCLUSIONS

Preliminary studies suggest that FK 506 may be an alternative immunosuppressive agent for pediatric and adolescent patients experiencing ongoing rejection or significant morbidity from cyclosporine and corticosteroids and in those patients dependent on corticosteroids for immune suppression.

Left atrial thrombus after lung transplantation

We report on a 16-year-old boy who developed a thrombus at the left atrial suture line after undergoing a bilateral sequential single lung transplantation. The diagnosis was made by transesophageal echocardiogram.

Critical issues in pediatric lung transplantation

Forty children (aged 1 to 18 years, 27 female and 13 male) have undergone heart-lung (21), double lung (17), and single lung (2) transplant procedures at our center from 1985 through April 1994. The indications for transplantation have been diverse, primary pulmonary hypertension (10), cystic fibrosis (11), congenital heart disease (10), arteriovenous malformation (3), emphysema (1), graft-versus-host disease (1), rheumatoid lung (1), cardiomyopathy (1), desquamative interstitial pneumonitis (1), and Proteus syndrome (1). The actuarial 1-year survival was 73% (mean follow-up 2 years). One-year actuarial survival for disease groups ranged from 60% for cystic fibrosis to 90% for congenital heart disease. We have identified six issues critical to the patient and programatic survival of pediatric lung transplantation. Our experience and management strategies in these areas are reviewed. Cytomegalovirus: Cytomegalovirus disease developed in six of eight patients with cytomegalovirus mismatching (donor +/recipient-) and in seven of 32 patients who survived more than 30 days (23%). All but cytomegalovirus donor -/recipient- patients were treated with ganciclovir for 4 weeks after transplantation. Obliterative bronchiolitis: Obliterative bronchiolitis developed in seven of 32 (25%) patients who survived more than 30 days. Obliterative bronchiolitis was manifest within the first posttransplantation year as a rapid decline in small airway function. Aggressive augmentation of immunosuppression has been used with little success. Posttransplantation lymphoproliferative disease: Posttransplantation lymphoproliferative disease developed in five of 32 (15%) patients who survived more than 30 days developed. One patient died (17% mortality) despite retransplantation. In four patients the disease resolved with reduction in immunosuppression alone, and one required the addition of interferon alfa. Cystic fibrosis: We have changed our management strategies to avoid triple drug immunosuppression, perioperative blood and bronchial cultures, aggressive antimicrobial therapy, and exclusion of patients with panresistant organisms; this has resulted in elimination of infectious mortalities thus far in the pediatric cystic fibrosis group. Airways: In 21 heart-lung recipients with tracheal anastomoses we have had no airway complications. The double and single lung transplant recipients accounted for 34 bronchial and one tracheal anastomoses. Three (9%) bronchial stenoses developed. Two were treated with silicone stents and one with balloon dilation.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of time-dependent risks for infection, rejection, and death after pulmonary transplantation

Infection and rejection remain the greatest threats to the survival of pulmonary allograft recipients. Furthermore, a relationship may exist between these events, because the occurrence of one may predispose to the other. By using multivariate analysis for repeated events, we analyzed the risk factors for bacterial, fungal, and viral infection, grade II or greater acute rejection, and death among 239 lung transplant recipients who received 250 allografts between January 1988 and September 1993. A total of 90 deaths, 491 episodes of acute rejection, and 542 infectious episodes occurred during a follow-up of 6 to 71 months. The hazard or risk patterns of death, infection, and rejection each followed an extremely high risk during the first 100 days after transplantation, a second modest risk period at 800 to 1200 days, and a lower constant risk. Infection and graft failure manifested by diffuse alveolar damage were the major causes of early death (< 100 days), whereas infection and chronic rejection were primary causes of later death after pulmonary transplantation. By multivariate analysis, cytomegalovirus mismatching risk for primary infection was the most significant risk factor for death, rejection, and infection. Absence of cytomegalovirus prophylaxis was also a risk factor for early and late death and late infection. Survival of recipients who received cytomegalovirus prophylaxis was significantly improved. Immunosuppression based on cyclosporine versus FK 506 was a risk factor for late death and late infection. Graft failure manifested by diffuse alveolar damage/adult respiratory distress syndrome was a significant risk for death late after transplantation. These data suggest the following: (1) The hazard for death, infection, and rejection after pulmonary transplantation appears biphasic; (2) lower survival is associated with ischemia-reperfusion lung injury represented by diffuse alveolar damage/adult respiratory distress syndrome; (3) cytomegalovirus mismatch, absence of cytomegalovirus prophylaxis, and development of cytomegalovirus disease are significant threats for death, rejection, and infection after pulmonary transplantation; (4) prevention of cytomegalovirus disease should improve survival by decreasing the prevalence of infection and rejection.

Indications for and results of single, bilateral, and heart-lung transplantation for pulmonary hypertension

The indications for single, bilateral, and heart-lung transplantation for patients with pulmonary hypertension remain controversial. We retrospectively analyzed the results from 11 single, 22 bilateral, and 24 heart-lung transplant procedures performed between January 1989 and January 1993 on 57 consecutive patients with pulmonary hypertension caused by primary pulmonary hypertension (n = 27) or Eisenmenger's syndrome (n = 30). Candidates with a left ventricular ejection fraction less than 35%, coronary artery disease, or Eisenmenger's syndrome caused by surgically irreparable complex congenital heart disease received heart-lung transplantation. All other candidates received single or bilateral lung transplantation according to donor availability. Although postoperative pulmonary artery pressures decreased in all three allograft groups, those in single lung recipients remained significantly higher than those in bilateral and heart-lung recipients. The cardiac index improved significantly in only the bilateral and heart-lung transplant recipients. A significant ventilation/perfusion mismatch occurred in the single lung recipients as compared with bilateral and heart-lung recipients because of preferential blood flow to the allograft. Graft-related mortality was significantly higher and overall functional recovery as assessed by New York Heart Association functional class was significantly lower at 1 year in the single as compared with bilateral and heart-lung recipients. Thus bilateral lung transplantation may be a more satisfactory option for patients with pulmonary hypertension with simple congenital heart disease, absent coronary arterial disease, and preserved left ventricular function. Other candidates will still require heart-lung transplantation.

Orthotopic heart transplantation in children with congenital heart disease

The early experience (February 1982 to June 1988) with transplantation for the treatment of congenital heart disease at the University of Pittsburgh was disappointing due to an excessively high perioperative mortality. From July 1988 to June 1992, a further 21 children with congenital heart disease underwent orthotopic transplantation. Thirteen had undergone multiple prior palliative procedures (mean, 2.8 per patient). In 12 of these patients, prior procedures involved the pulmonary arteries on one or more occasions. In contrast to our earlier experience, there were no deaths stemming from inadequate surgical reconstruction or pulmonary hypertension. The actuarial survival was 71% at both 1 and 3 years. This did not differ significantly from the survival among 18 patients who underwent transplantation for the management of cardiomyopathy over the same period (1-year and 3-year survival, 83%). The perioperative mortality and short-term survival are now similar for children undergoing transplantation for the treatment of either congenital heart disease or cardiomyopathy. These improved results probably reflect more careful patient selection and an increasing surgical experience with complex reconstructive procedures.

Development of an intravenous membrane oxygenator: a new concept in mechanical support for the failing lung

An intravenous membrane oxygenator is being developed to supplement oxygen and carbon dioxide exchange in patients with temporary and potentially reversible lung failure in either a lung transplantation setting or in cases of acute respiratory distress from multiple causes. Our device incorporates a pulsatile balloon that is centrally located and around which are mounted microporous hollow fibers. Oxygen is vaccuumed through the fibers with resultant gas exchange. The rhythmic pulsations of the balloon enhance cross-flow and three-dimensional convective mixing at the blood-fiber interface and thus promote more efficient oxygen-carbon dioxide exchange. Seven intravenous membrane oxygenator prototypes have been designed and fabricated. Modifications in design have led to a progressive improvement in gas flux. Gas exchange performance measured in vitro and with both saline solution and fresh ox blood have shown gas exchange as high as 203 ml/min/m2 for oxygen and 182 ml/min/m2 for carbon dioxide. In vivo dog experiments with the device positioned in the inferior vena cava and right atrium have shown over a 50% increase in oxygen flux with balloon activation versus the static situation without changes in hemodynamics. The size of the prototype tested in animals can be scaled up fivefold for anticipated human trials. Our results indicate that our intravenous membrane oxygenator prototypes now under development may be an alternative to extracorporeal membrane oxygenation in the treatment of temporary respiratory failure.

Psychosocial predictors of vulnerability to distress in the year following heart transplantation

This study examines psychological symptomatology in a cohort of 72 heart transplant recipients followed longitudinally during their first year post-transplant. In keeping with research on other domains of life stressors and illnesses, a central study goal was to identify pre-transplant and perioperative psychosocial factors associated with increased vulnerability to, and maintenance of, elevated psychological distress levels post-transplant. Average anxiety and depression levels, but not anger-hostility symptoms, were substantially elevated in the early post-transplant period, relative to normative data. Average symptom levels improved significantly over time, although one-third of the sample continued to have high distress levels at all follow-up assessments. Recipients with any of seven psychosocial characteristics at initial interview were particularly susceptible to continued high average distress levels over time: a personal history of psychiatric disorder prior to transplant; younger age; lower social support from their primary family caregiver; exposure to recent major life events involving loss; poor self-esteem; a poor sense of mastery; and use of avoidance coping strategies to manage health problems. Recipients without such factors showed improvement in average distress levels across the assessment period. These effects were stronger for anxiety than depressive symptoms, with the exception of a sizeable relationship between loss events and subsequent depression. The findings suggest that clinical interventions designed to minimize prolonged emotional distress post-transplant need to be closely tailored to heart recipients' initial psychosocial assets and liabilities.

Risk stratification using the Society of Thoracic Surgeons Program

In an era of progressive cost containment and public scrutiny, the wisdom of aggressive surgical therapy for high-risk candidates has been questioned. At our center in the previous 24 months, 728 patients with coronary artery disease were entered into The Society of Thoracic Surgeons national database, and the hospital outcomes plus length of stay were analyzed. Patients were separated according to the predicted mortality based on the groupings in The Society of Thoracic Surgeons database: 0 to 5% (453 patients); 5% to 10% (126 patients); 10% to 20% (96 patients); 20% to 30% (17 patients); and 30% and greater (36 patients). There was a close correlation with the predicted rates of mortality. Importantly, the preoperative risk stratification demonstrated a strong correlation with the significant morbidity and excessive length of stay in the highest-risk groups (predicted risk of 20% to > or = 30%). The incidences of the most common complications in the group with the highest predicted risk (> or = 30%) were 28%, renal failure; 33%, ventilator dependence; and 17%, cardiac arrest. In addition, at short-term follow-up (6 to 8 months), a 24.3% mortality was identified in patients with a predicted mortality that exceeded 20%. These data quantify the risks and morbidities associated with the care of seriously ill patients with coronary artery disease and demonstrate the need for professional and public discussions focusing on the association of a high preoperative risk status and the consumption of resources.

Extracorporeal membrane oxygenation support as a bridge to pediatric heart transplantation

BACKGROUND

Mechanical circulatory support for intractable heart failure as a bridge to transplantation has been used infrequently in children. The lack of clinically available ventricular assist devices has resulted in the use of conventional extracorporeal circuits with oxygenator as the main modality for circulatory support. In this study we reviewed our experience with extracorporeal membrane oxygenation (ECMO) support in children with irreversible heart failure who were awaiting heart transplantation.

METHODS AND RESULTS

Since 1985, 14 children were placed on ECMO support for circulatory failure and were considered candidates for heart transplantation: 8 children had postcardiotomy contractile failure, 3 had dilated cardiomyopathy, and 3 had viral myocarditis. Five of these children had cardiac arrest and were placed on support during cardiopulmonary resuscitation. Mean duration of ECMO support was 109 +/- 20 hours. Eight patients developed pulmonary edema requiring decompression of the left ventricle, 3 by blade atrial septostomy and 5 by left atrial vent cannula. Nine of 14 received a heart transplant, 1 child recovered spontaneously (myocarditis), and 4 died of sepsis on ECMO. Of the children who received transplants, 6 were early survivors with 1 late death (lymphoproliferative disease), for a total of 7 of 14 (50%) early and 6 of 14 (43%) late survivors.

CONCLUSIONS

Our experience suggests that ECMO is an effective means of circulatory support as a bridge to transplantation in children. Decompression of the left ventricle is often required to prevent pulmonary edema. Sepsis and bleeding remain a limitation to prolonged mechanical support with ECMO in children.

Assessment of the response of right ventricular performance to decreasing levels of mechanical assistance by on-line pressure area relationships

The rapid assessment of the response of right ventricular (RV) performance to decreasing levels of mechanical assistance may be an important adjunct in determining if a patient can tolerate the removal of such a device. This report describes the use of on-line pressure area relationships to assess RV function in a patient supported with an RV assist device (RVAD). Mid RV short axis cross-sectional area was measured on-line by transesophageal echocardiography with an automated endocardial border detection feature. RV pressure was measured with a high fidelity catheter. Pressure and area were plotted simultaneously on a computer workstation interfaced with the pressure and echo systems to yield on-line pressure area loops. The following indices of RV performance were calculated while RVAD flow was decreased in 1 L/min increments: stroke work' (SW' = integral of PdA)[mmHg*cm2], stroke area (SA = Maximum Area-Minimum Area)[cm2], and fractional area change (FAC = SA/Maximum Area*100)[%]. SW', SA, and FAC significantly increased with decreasing RVAD flow: SW'(from 32 to 61 mmHg*cm2), SA (from 2.58 to 4.37 cm2), and FAC (from 20 to 32%). In conclusion, the increase in these parameters of RV performance with decreasing mechanical assistance suggested that this patient would tolerate removal of the RVAD, which was subsequently successful. This method of on-line pressure area relationships may be useful to predict the need for further mechanical assistance.

Management of a tracheal bronchus in a pediatric lung transplant recipient

Successful pediatric lung transplantation requires intraoperative identification and management of unforeseen anomalies in the recipient. Effective technical improvisation combines awareness of bronchial anatomic anomalies with experience in recent modifications in airway anastomotic techniques. We report a case of successful bilateral sequential double-lung transplantation in a child with the right upper lobe bronchus arising from the trachea.

Pseudomonas cepacia empyema necessitatis after lung transplantation in two patients with cystic fibrosis

Lung transplantation is an accepted modality for patients with cystic fibrosis (CF) who have end-stage respiratory failure. The postoperative course of these patients is often complicated by serious infections with organisms such as Pseudomonas aeruginosa and Pseudomonas cepacia that may be multiply resistant to conventional antimicrobial agents. We describe two patients with CF who, after double lung transplantation, developed the unusual complication of empyema and empyema necessitatis due to P cepacia that was resistant to all tested antibiotics.

Pregnancy after cardiac transplantation

A 39-year-old gravida 3, para 1102 underwent heart transplantation in 1990 for end-stage ischemic cardiomyopathy. She was immunosuppressed with FK506 and experienced no episodes of rejection or infection. She conceived in 1992 and her pregnancy was complicated by preeclampsia at 33 weeks' gestation. She delivered a 2093 g female infant with mild and transient neonatal complications. This patient's pregnancy course and successful outcome is consistent with other reported cases.

A prospective randomized trial of FK506 versus cyclosporine after human pulmonary transplantation

We have conducted a unique prospective randomized study to compare the effect of FK506 and cyclosporine (CsA) as the principal immunosuppressive agents after pulmonary transplantation. Between October 1991 and March 1993, 74 lung transplants (35 single lung transplants [SLT], 39 bilateral lung transplant [BLT]) were performed on 74 recipients who were randomly assigned to receive either FK or CsA. Thirty-eight recipients (19 SLT, 19 BLT) received FK and 36 recipients (16 SLT, 20 BLT) received CsA. Recipients receiving FK or CsA were similar in age, gender, preoperative New York Heart Association functional class, and underlying disease. Acute rejection (ACR) was assessed by clinical, radiographic, and histologic criteria. ACR was treated with methylprednisolone, 1 g i.v./day, for three days or rabbit antithymocyte globulin if steroid-resistant. During the first 30 days after transplant, one patient in the FK group died of cerebral edema, while two recipients treated with CsA died of bacterial pneumonia (1) and cardiac arrest (1) (P = NS). Although one-year survival was similar between the groups, the number of recipients free from ACR in the FK group was significantly higher as compared with the CsA group (P < 0.05). Bacterial and viral pneumonias were the major causes of late graft failure in both groups. The mean number of episodes of ACR/100 patient days was significantly fewer in the FK group (1.2) as compared with the CsA group (2.0) (P < 0.05). While only one recipient (1/36 = 3%) in the group treated with CsA remained free from ACR within 120 days of transplantation, 13% (5/38) of the group treated with FK remained free from ACR during this interval (P < 0.05). The prevalence of bacterial infection in the CsA group was 1.5 episodes/100 patient days and 0.6 episodes/100 patient days in the FK group. The prevalence of cytomegaloviral and fungal infection was similar in both groups. Although the presence of bacterial, fungal, and viral infections was similar in the two groups, ACR occurred less frequently in the FK-treated group as compared with the CsA-treated group in the early postoperative period (< 90 days). Early graft survival at 30 days was similar in the two groups, but intermediate graft survival at 6 months was better in the FK group as compared with the CsA group.

Effect of cardiopulmonary bypass on early graft dysfunction in clinical lung transplantation

The records of 100 lung transplant recipients (13 heart-lungs, 45 double-lungs, and 42 single-lungs) from September 1990 through April 1992 were reviewed to determine the role of cardiopulmonary bypass (CPB) in early graft dysfunction. Fifty-five patients requiring CPB (CPB group) for 186 +/- 54 minutes were compared with the 45 patients without CPB (no-CPB group). All of the heart-lung and en-bloc double-lung transplantations were performed under CPB, with pulmonary vascular lung disease the principal diagnosis, resulting in a significantly younger age population in the CPB group. All other donor- and recipient-related factors matched well in both groups. Of 38 bilateral single-lung transplantations, CPB was used in 18. In double-lung and heart-lung recipients gas exchange of the allografts was evaluated by the arterial/alveolar oxygen tension ratios at nine intervals during the first 72 hours. The mean arterial/alveolar oxygen tension ratio in the CPB group was 0.48 +/- 0.19, significantly lower than in the no-CPB group with 0.60 +/- 0.22 (p = 0.025). All patients had radiographic interpretation and scoring of pulmonary infiltrates from chest roentgenograms taken within 12 hours after reperfusion. The CPB group had more severe pulmonary infiltrates than the no-CPB group (p = 0.034). Prolonged intubation defined as 7 days or longer occurred significantly more often (29/55) in the CPB group than in the no-CPB group (8/45) (p = 0.003). Actuarial graft and patient survival at 1 month was better in the no-CPB group than in the CPB group (42/45 versus 44/55 [p = 0.05] and 43/45 versus 45/55 [p = 0.033], respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomotic pitfalls in lung transplantation

Although airway, arterial, and venous connections required for lung transplantation appear simple, in practice we have encountered morbid early stenosis and obstructions, which are now avoided by technical modifications gradually made since 1985 in 134 cases (60 single lung and 74 double lung). Our initial eight double lung transplant procedures were done with tracheal anastomoses and omental wraps, but ischemic disruption, with a 75% (6 of 8) rate of complications, resulted in the subsequent use of bi-bronchial connections. A total of 192 bronchial anastomoses were reviewed (60 single lung, 66 double lung). Although all anastomoses were constructed between the donor trimmed to one to two rings above the upper lobe origin and the host divided at its emergence from the mediastinum, the suture technique has evolved. Nine (32%) of 28 cases with early bronchial anastomoses with end-to-end suture and intercostal muscle wrap had ischemic or stenotic complications, but the telescoping technique without wrap in 164 bronchial anastomoses reduced the problem to 12% (19 of 164). Twelve anastomoses required temporary intraluminal stenting. Vascular anastomotic obstructions occurred in five arterial (excessive length 2, short allograft artery 1, restrictive suture or clot 2) and two venous (excessive length 1, restrictive suture or clot 1) connections. Suspicion of arterial obstruction was prompted by persisting pulmonary hypertension and reduced flow to the allograft measured by postoperative nuclear scan and hypoxia. Venous obstructions were suggested by persisting radiographic and clinical pulmonary edema. Modifications of earlier techniques have improved our early success in lung transplantation and might be considered by others entering this demanding field.

Experience with pediatric lung transplantation

Heart-lung transplantation and lung transplantation have become accepted techniques in adult patients with end-stage cardiopulmonary disease. We report here our experience between July 1985 and March 1993 with 34 children (< 20 years) who underwent heart-lung (n = 18) or lung transplantation (n = 17). Indications for transplantation included cystic fibrosis (n = 9), congenital heart disease with Eisenmenger complex (n = 9), primary pulmonary hypertension (n = 8), pulmonary arteriovenous malformations (n = 2), desquamative interstitial pneumonia (n = 2), Proteus syndrome with multicystic pulmonary disease (n = 1), graft-versus-host disease (n = 1), rheumatoid lung disease (n = 1), and bronchiolitis obliterans and emphysema (n = 1). Twenty-six patients (76%) have survived from 1 to 88 months after transplantation; most patients have returned to an active lifestyle. Of the eight deaths, four were due to infections, two to multiorgan failure, 1 to posttransplant lymphoproliferative disease, and one to donor organ failure. Four of the patients who died had cystic fibrosis. Despite considerable morbidity related to infection, rejection, and function of the heart-lung and lung allograft in some patients, our results with this potentially lifesaving procedure in the pediatric population have been encouraging.

A clinical trial comparing University of Wisconsin solution and cold cardioplegic solution with load-independent mechanical parameters

To evaluate the efficacy of University of Wisconsin solution for clinical heart transplantation, load-independent parameters were used to assess left ventricular function after transplantation. Donor hearts were arrested with and stored in buffered cold cardioplegic solution for control (n = 5) and University of Wisconsin solution for the experimental group (n = 5). Orthotopic transplantations were performed in a routine manner. Mean donor age (cardioplegic solution, 28 +/- 5.2 years; University of Wisconsin solution, 28 +/- 5.1 years) and ischemic times (cardioplegic solution, 181 +/- 27 minutes; University of Wisconsin solution, 224 +/- 23 minutes) were similar. Two hours after reperfusion of the heart, transesophageal echocardiography was used to image the left ventricle at the mid-papillary muscle level, and a high-fidelity catheter-tipped manometer was placed in the left ventricle to record left ventricular pressure simultaneously. These images were digitized during apneic baseline conditions and during an acute reduction in preload from inferior vena caval occlusion. The left ventricular cross-sectional areas were measured and matched with left ventricular pressure from the catheter-tipped manometer to reveal pressure-area relationships. The baseline parameters fractional area change and stroke force were calculated. End-systolic elastance, the slope of end-systolic pressure-area relationship and preload recruitable stroke force, the slope of stroke force versus end-diastolic area were calculated from the inferior vena cava occlusion measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic mechanical circulatory support: rehabilitation, low morbidity, and superior survival

Because of donor scarcity, 12 (39%) of a series of 31 Novacor left ventricular assist system recipients required mechanical circulatory support for an average of 125 days before transplantation (range, 61 to 303 days). Ten received a heart transplant and all survived to discharge. Two died of infection before transplantation after 93 and 303 days of support. Significant reductions were noted from preimplantation values of right and left cardiac filling pressures. Right ventricular ejection fraction and cardiac index increased. The 4-month actuarial freedom from infection during support was 75%. Three patients benefited from chronic outpatient housing for 5, 18, and 131 days, respectively, with improvements in quality of life measures. Ten chronically supported patients participated in an intensive rehabilitative exercise program resulting in an improvement of New York Heart Association class from IV to I in 9 patients. Mean oxygen consumption, which was 10 mL.kg-1.min-1 30 days after implantation (mean exercise time, 10 minutes) had risen to 15 mL.kg-1.min-1 before transplantation (mean exercise time, 16 minutes). This series suggests that long-term circulatory support is compatible with low morbidity, significant physical and hemodynamic rehabilitation, and an outpatient setting.

Pediatric lung transplantation: expanding indications, 1985 to 1993

The application of lung transplantation to the pediatric population was a natural extension of the success realized in our adult transplant program, which began in 1982. Thirty-two pediatric patients (age range 1 to 18 years) have undergone heart-lung (n = 16), double-lung (n = 14), and single-lung (n = 2) transplantation procedures. The cause of end-stage lung disease was primary pulmonary hypertension (n = 7), congenital heart disease (n = 7), cystic fibrosis (n = 9), pulmonary arteriovenous malformation (n = 2), desquamative interstitial pneumonitis (n = 2), graft-versus-host disease (n = 1), emphysema (n = 1), rheumatoid lung (n = 1), cardiomyopathy (n = 1), and Proteus syndrome (n = 1). Six patients (19%) underwent pretransplantation thoracic surgical procedures. The survival rate was 78% at a mean follow-up of 1.8 years. The survival rate in the 23 recipients without cystic fibrosis was 87% (95% since 1985). The actuarial 1-year survival rate in the nine recipients with cystic fibrosis was 55%. Immunosuppression was cyclosporine (n = 9) or FK 506 (n = 23)-based therapy with azathioprine and steroids. Children were followed up by spirometry, transbronchial biopsy, and primed lymphocyte testing of bronchoalveolar lavage fluid. The mean number of treated episodes of rejection per patient in the groups treated with cyclosporine and FK 506, respectively, was 1.0 and 1.2 at 30 days, 0.67 and 0.38 at 30 to 90 days, and 2.33 and 0.46 at greater than 90 days (p < 0.001, Fisher exact test).(ABSTRACT TRUNCATED AT 250 WORDS)

Improved survival following pediatric cardiac transplantation in high-risk patients

BACKGROUND

Preoperative hemodynamic support, complex congenital heart disease, and elevated pulmonary vascular resistance present particular challenges for pediatric heart transplantation. This study was performed to identify preoperative factors that influence survival after pediatric heart transplantation over two eras of pediatric heart transplant experience.

METHODS AND RESULTS

We retrospectively analyzed demographic, clinical, and hemodynamic data from 67 pediatric patients who underwent heart transplantation between February 1982 and June 1992 and compared survival between two eras (early experience versus late experience). During the early experience (group 1: February 1982 to August 1989), univariate analysis identified congenital heart disease, pretransplant extracorporeal membrane oxygenator (ECMO) support, inotropic and/or ventilatory support (UNOS status I), elevated transpulmonary gradient (at least 15 mm Hg), and elevated pulmonary vascular resistance index (at least 4 Wood units.m2) as preoperative risk factors for early death after pediatric heart transplantation. However, in the late experience (group 2: September 1989 to June 1992), the only risk factor for premature death by univariate analysis was elevated transpulmonary gradient. By multivariate analysis, elevated transpulmonary gradient was the only risk factor for our early, late, and entire experiences. One-year survival after transplantation for congenital heart disease was improved from 46% in group 1 to 73% in group 2 (P < .05). In group 1, only one patient (25%) with pretransplant ECMO support survived 1 year, whereas 66% (four of six) survived more than 1 year in group 2.

CONCLUSIONS

Although elevated transpulmonary gradient continues to be a significant risk factor for pediatric heart transplantation, candidates with congenital heart disease, UNOS status I, and pretransplant ECMO support now can be successfully transplanted with reasonable hope for extended survival.

Clinical cardiopulmonary bypass without systemic anticoagulation

Heparin-coated perfusion systems have been used to perform cardiopulmonary bypass with decreased systemic heparin dosages. We report the case of a 60-year-old man with end-stage liver disease and severe aortic stenosis who underwent an aortic valve replacement without systemic anticoagulation, employing a heparin-coated perfusion system. In patients with a contraindication to systemic anticoagulation, cardiopulmonary bypass with a heparin-coated system without systemic anticoagulation may be a viable alternative.

Isolated lung transplantation for patients with Eisenmenger's syndrome

BACKGROUND

Eisenmenger's syndrome remains one of the greatest challenges in lung transplantation.

METHODS AND RESULTS

Since October 1990, seven such patients with Eisenmenger's syndrome received isolated pulmonary grafts (six double lungs and one single lung). Mean patient age was 32 +/- 6 years (two men and five women). The preoperative mean pulmonary arterial pressure was 90.7 +/- 31.2 mm Hg, and the ventriculoscintigram showed markedly enlarged right ventricle and normal left ventricular function with ejection fraction of 0.660 +/- 0.115. Three atrial septal defects and four patent ducti arteriosus were repaired concomitantly. Excised lung histology showed plexogenic pulmonary arteriopathy with Heath-Edwards' grade 4 through 6. One double lung patient who had preexisting systemic vascular collapse died intraoperatively. The other six patients tolerated transplantation, and on the first operative day, mean pulmonary artery pressure decreased to 22.4 +/- 7.3 mm Hg (P < .002) and gas exchange was acceptable with an arterial/alveolar oxygen tension ratio of 0.47 +/- 0.15. Two patients died of mediastinal and pulmonary infection. The follow-up for the four survivors ranged from 13 to 25 months after transplantation.

CONCLUSIONS

Our preliminary experience shows that concomitant isolated lung transplantation with cardiac repair could be a viable therapeutic option for patients with Eisenmenger's syndrome and normal left ventricular function. Dynamic right ventricular outflow obstruction is a potential hemodynamic problem in these pulmonary recipients.

Preoperative pulmonary hemodynamics and early mortality after orthotopic cardiac transplantation: the Pittsburgh experience

The influence of preoperative transpulmonary pressure gradient (TPG) and pulmonary vascular resistance (PVR) on early post-transplant mortality was evaluated in 425 orthotopic transplant recipients. The overall 30-day post-transplant mortality rate was 12.5%; the majority of the deaths (52.8%) were due to primary allograft failure. The 0- to 2-day mortality rate was threefold higher in patients with severe preoperative pulmonary hypertension (TPG > or = 15 mm Hg or PVR > or = 5 Wood units), whereas the 3- to 7-day and 8- to 30-day mortality rates were similar. Early post-transplant mortality (0 to 2 days and 8 to 30 days) was also significantly higher (15.9% vs 3.9% and 9.9% vs 2.8%, respectively; p < 0.05) in women compared with men. Women with severe preoperative pulmonary hypertension had higher (p < 0.05) 0- to 2-day post-transplant mortality than comparable men. According to univariate analysis, recipients with preoperative TPG > or = 15 mm Hg had a significantly higher 30-day postoperative mortality rate, irrespective of their level of PVR. Furthermore, patients with severe preoperative pulmonary hypertension who underwent transplantation between 1980 and 1987 had a higher 0- to 2-day post-transplant mortality rate compared with patients operated on after that time. Multiple logistic regression analysis identified female recipient sex and preoperative TPG but not preoperative PVR, era of transplantation, or recipient age as significant (p < 0.001 and p < 0.01, respectively) independent predictors of early post-transplant mortality.

A decade of lung transplantation

OBJECTIVE

The experience accrued at the University of Pittsburgh between March 1982 and December 1992 in the various forms of lung transplantation, including heart-lung, double lung, and single lung, is discussed.

SUMMARY BACKGROUND DATA

Heart-lung (n = 97) was the most commonly performed operation followed by double lung (n = 80) and single lung (n = 68). Major indications included primary pulmonary hypertension (n = 76), obstructive lung disease (n = 57), Eisenmenger's syndrome (n = 42), cystic fibrosis (n = 32), and retransplantation (n = 13). Since May 1991, 115 procedures have been performed and heart-lung transplantation has decreased from 61% to 15% of the cases with a corresponding doubling in double lung from 24% to 43% and single lung from 15% to 42%.

RESULTS

The 1-, 2-, and 5-year survival rates in all 232 recipients were 61%, 55%, and 44%, respectively. The actuarial survival rate was significantly better for those 107 recent recipients compared to the 125 early recipients (70% vs. 61%). Overall, the 63 single (70%) and 74 double (65%) lung procedures were more successful than heart-lung transplantation (53%). Recently, however, lung transplantation has been associated with an improvement in the survival rate from 48% to 72%. The survival rate has also improved from 53% to 77% for single lung transplant recipients. The causes of death in 106 recipients included infection (n = 40), early allograft dysfunction (n = 23), obliterative bronchiolitis (n = 13), and inoperative bleeding (n = 10). Poor outcomes also included technical problems (n = 6), lymphoma (n = 4), acute rejection (n = 3), diaphragmatic paralysis (n = 2), multisystem organ failure (n = 2), stroke (n = 2), liver failure (n = 1), and airway dehiscence (n = 1).

CONCLUSIONS

The long-term outlook for lung transplant recipients has improved. There appears to be significant conservation of organs with single lung and double lung transplantation, finding greater acceptance for diseases once exclusively treated by heart-lung transplantation alone. The improved long-term outlook will be dependent upon better treatment for chronic rejection of the airways that histologically is defined by obliterative bronchiolitis.

Septal myectomy with a carbon dioxide laser for hypertrophic cardiomyopathy

Septal myectomy with a noncontact carbon dioxide laser for hypertrophic cardiomyopathy is described. This technique results in improved visualization of the septum as the laser beam is held outside the heart and the resecting laser beam can always be clearly seen. We believe this approach provides an improved method of septal myectomy in hypertrophic cardiomyopathy.

Acquired right ventricular outflow tract obstruction after lung transplantation: diagnosis by transesophageal echocardiography

Acute reduction in pulmonary pressures after lung transplantation for severe chronic pulmonary hypertension may produce a sudden decrease in cavity size of a hypertrophied right ventricle resulting in acquired right ventricular outflow tract obstruction. This case illustrates the utility of transesophageal echocardiography with continuous-wave Doppler to make a morphologic as well as hemodynamic diagnosis of acquired right ventricular outflow tract obstruction in a patient after lung transplantation.