Validation of an electrocardiographic algorithm for the detection of cardiac amyloidosis

Background

Despite new therapies, diagnosis of cardiac amyloidosis (CA) is often delayed. We recently developed a simple electrocardiographic (ECG) algorithm to suspect CA without the aid of advanced imaging modalities (Figure).

Methods

The aim of this study was to validate the algorithms' usefulness in clinical practice. ECG readings from patients with CA, heart failure with preserved ejection fraction (HFpEF), and hypertrophic cardiomyopathy (HCMP) were analyzed in a blinded fashion.

Results

884 patients were included. Patients with pacemakers were excluded, leaving 827 ECGs (237 CA, 407 HFpEF, 183 HCMP) for final analysis. A characteristic pattern defined by the algorithm was visually perceptible in 165 ECGs (69.6%) of the amyloidosis patients vs. 114 (28%) of HFpEF vs. 22 (12.0%) of HCMP patients (p<0.001). The area under the curve (AUC) for the detection CA was 0.75 with a sensitivity of 69.6% and a specificity of 76.9% (Figure). Binary logistic regression analysis revealed that the presence of a distinctive pattern increased the probability of CA with an odds ratio of 7.66 (CI: 5.47–10.72; p<0.001).

Conclusion

This easy-to-use ECG algorithm has proven helpful to suspect CA. Our tool may significantly improve the treatment of heart failure patients by identifying those with amyloidosis-related disease.

Funding Acknowledgement

Type of funding sources: None.

Two-dimensional speckle-tracking echocardiography in tafamidis-treated patients with transthyretin amyloid cardiomyopathy: a glimmer of hope for viable therapy monitoring?

Background

Treatment with Tafamidis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) has been shown to have beneficial effects on the left ventricle (LV), as assessed by cardiac magnetic resonance (CMR) imaging. Although CMR represents the gold standard among imaging modalities, its limited availability in clinical practice makes it unfeasible for routine therapy monitoring.

Purpose

We aimed to determine Tafamidis-induced changes using two-dimensional (2D) speckle-tracking echocardiography and to identify echocardiographic imaging parameters that could be used for specific therapy monitoring.

Methods

We subjected a series of ATTR-CM patients to transthoracic echocardiography (TTE) at baseline and follow-up and compared patients treated with Tafamidis 61mg once daily (QD) to a historical control cohort treated with Tafamidis 20mg QD, as well as to a historical treatment-naïve control cohort reflecting the natural course of the disease.

Results

Patients receiving Tafamidis 61mg (n=62) or 20mg (n=21) QD showed stable measurements at follow-up [61mg: 8.5 months, 20mg: 7.0 months] in LV global longitudinal strain (GLS) (61mg: −11.75% vs. −11.58%, p=0.534; 20mg: −10.61% vs. −10.12%, p=0.309), right ventricular (RV) GLS (61mg: −14.18% vs. −13.72%, p=0.377; 20mg: −14.53% vs. −13.99%, p=0.452) and left atrial (LA) reservoir strain (LASr; 61mg: 8.80% vs. 9.42%, p=0.283; 20mg: 8.23% vs. 8.67%, p=0.589), whereas treatment-naïve ATTR-CM patients (n=54) had clear signs of disease progression at the end of the observation period [10.5 months; LV-GLS: −11.71% vs. −10.59%, p=0.001; RV-GLS: −14.36% vs. −12.99%, p=0.038; LASr: 10.67% vs. 8.41%, p=0.005]. Between-group comparison at follow-up revealed beneficial effects of Tafamidis 61mg on LASr (p=0.003), LV-GLS (p=0.030) and interventricular septum (IVS) thickness (p=0.006), resulting in clinical benefits (six-minute walk distance (6-MWD): p=0.006, NT-proBNP: p≤0.001), while patients treated with Tafamidis 20mg QD showed positive effects on LASr (p=0.039) but no differences in LV-GLS (p=0.274), IVS thickness (p=0.068) and clinical status (6-MWD: p=0.124, NT-proBNP: p=0.053) compared to the natural course.

Conclusion

Treatment with Tafamidis 61mg in ATTR-CM patients delays the increase in IVS thickness and the deterioration of LA and LV longitudinal function, resulting in significant clinical benefits compared with natural history. Serial TTE with 2D speckle-tracking imaging may be appropriate for disease-specific therapy monitoring.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This work was supported by the Pfizer Inc. However, Pfizer Inc. did not have influence on study design, data processing, or statistical analysis.

Quantification of myocardial amyloid deposition in tafamidis-treated patients with transthyretin amyloid cardiomyopathy

Background

Tafamidis kinetically stabilizes the tetrameric form of transthyretin (TTR) and thus may halt disease progression in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). However, the effect of tafamidis treatment on the progression of myocardial amyloid deposition is still unclear.

Methods

In our explorative analysis, we aimed to investigate the treatment effect of tafamidis on myocardial amyloid deposition measured by myocardial standardized uptake value (SUV) peak and SUV retention index using quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) of the thorax and to observe its association with clinical parameters. Therefore, clinical, laboratory, imaging, and SPECT/CT examinations were performed in twenty consecutive ATTR-CM patients who started treatment with tafamidis 61mg, both at baseline and at a median of 6 months.

Results

Main results are summarized in Table 1. In brief, we observed a significant reduction of mean myocardial SUV peak (baseline: 15.50 vs. follow-up: 11.61, p<0.001) and mean SUV retention index (5.64 vs. 3.58, p=0.001) after treatment with tafamidis (Figure 1A). Interestingly, a higher percentage decrease in the SUV retention index is more likely to be associated with clinical benefit, with a threshold of −30% distinguishing between patients who respond clinically (n=12) and those who do not (n=8, Figure 1B). Clinical response is demonstrated by improvement in exertional dyspnea (NYHA class III: 83.3% vs. 41.7%, p=0.047) and mean functional capacity as measured by 6-minute walk distance (349.5m vs. 356.7m, p=0.736). Cardiac biomarkers analysis showed a clear reduction in median NT-proBNP levels in the responder cohort (2765.0 pg/mL vs. 1904.0 pg/mL, p=0.041) compared to an increase in the non-responder cohort (1825.0 pg/mL vs. 1944.0 pg/mL, p=0.208; cohort comparison: p=0.026, Figure 1C). Echocardiographic findings revealed improvement in mean left ventricular (LV) strain (−12.0% vs. −13.5%, p=0.049) and mean LV ejection fraction (LVEF, 48.5% vs. 52.7%, p=0.287) in the responder cohort, while significant deterioration in mean LV function (LV strain: −13.9 vs. −10.5, p=0.035; LVEF: 53.2% vs. 46.5%, p=0.012) was observed in the non-responder cohort, with an additional substantial deterioration in right ventricular (RV) function as measured by tricuspid annular plane systolic excursion (TAPSE, mean, BL: 19.2mm vs. FU: 12.6mm, p=0.037) in those patients. These results are consistent with changes in the LV and RV function in cardiac magnetic resonance imaging parameters in each of the two cohorts.

Conclusion

Treatment with tafamidis in patients with ATTR-CM results in a significant reduction in myocardial amyloid deposition as measured by the SUV retention index, with a threshold of −30% distinguishing patients who respond clinically from those who do not. However, a larger patient sample is needed to verify these results.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Pfizer Inc.

A machine learning-derived electrocardiographic algorithm for the detection of cardiac amyloidosis

Background

The diagnosis of cardiac amyloidosis (CA) requires advanced imaging techniques. Typical surface ECG patterns have been described, but their diagnostic value is limited.

Purpose

The aim of this study was to perform a comprehensive electrophysiological characterization in CA patients and to develop a robust, easy-to-use diagnostic tool.

Methods

First, we applied electrocardiographic imaging (ECGI) to generate detailed electroanatomical maps in CA patients and controls. Then, a machine learning approach was used to generate a surface ECG-based diagnostic algorithm from the complex dataset.

Results

Areas of low voltage were localized in the basal inferior regions of both ventricles and the remaining right ventricular segments in CA. The earliest epicardial breakthrough of myocardial activation was visualized in the right ventricle. Potential maps showed an accelerated and diffuse propagation pattern. We correlated the results from ECGI with 12-lead ECG recordings. Ventricular activation correlated best with R-peak timing in leads V1 to V3. Epicardial voltage showed a strong positive correlation with R-peak amplitude in inferior leads II, III, aVF. Ten blinded cardiologists were then asked to identify CA patients by analyzing 12-lead ECGs before and after training for the defined ECG patterns. Training resulted in significant improvements in the detection rate of CA with an AUC of 0.69 before and 0.97 after training (Figure).

Conclusion

Using a machine learning approach, a robust ECG-based tool was developed to detect CA from detailed electroanatomical mapping of CA patients. The developed tool proved to be a simple and reliable diagnostic tool to suspect CA without the aid of advanced imaging modalities.

Funding Acknowledgement

Type of funding sources: None.

Cardiac imaging in tafamidis-treatment patients with transthyretin amyloid cardiomyopathy

Background

Tafamidis kinetically stabilizes the tetrameric form of transthyretin (TTR) and thus may halt disease progression in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). In our explorative analysis, we aimed to investigate the treatment effect on functional capacity and cardiac biomarkers as well as cardiac function and structure using echocardiography and cardiac magnetic resonance imaging (CMR), and to compare patients treated with tafamidis with an untreated control cohort.

Methods

Consecutive ATTR-CM patients either received tafamidis 61mg (n=64) or tafamidis 20mg (n=23) or were assigned to an untreated control cohort (n=54) reflecting the natural history of the disease. Subsequently, we performed clinical, laboratory, echocardiography and CMR follow-up at a median of 9 to 12.5 months.

Results

Main results are summarized in Table 1. In brief, we observed evidence of improvement in functional capacity as measured by the 6-minute walk distance (6MWD) in tafamidis 61mg treated patients (baseline: 377.1m vs. follow-up: 383.2m, p=0.678) compared to a significant decline in mean 6MWD in untreated patients (388.1m vs. 336.4m, p=0.002; cohort comparison: p=0.005). Analysis of cardiac biomarkers revealed evidence of therapeutic response by a decrease in median NT-proBNP levels in patients treated with tafamidis 61mg (2633.0pg/mL vs. 2244.0pg/mL, p=0.366), whereas a significant increase was observed in untreated patients (2798.0pg/mL vs. 3422.0pg/mL, p<0.001; cohort comparison: p<0.001). Echocardiographic findings revealed evidence of approximate stabilization in mean left ventricular (LV) strain (−11.75% vs. −11.58%, p=0.534) and mean right ventricular (RV) strain (−14.18% vs. −13.72, p=0.377) in the tafamidis 61mg treatment cohort compared to significant deterioration of mean LV longitudinal function (−11.71% vs. −10.59%, p=0.001) and mean RV longitudinal function (−14.36% vs. −12.99%, p=0.038) in the untreated cohort (cohort comparison: p=0.030 and p=0.269). Furthermore, cardiac structural assessment by CMR showed a significant increase in mean LV mass (199.1g vs. 214.3g, p=0.040) and mean extracellular volume (50.52% vs. 55.96%, p=0.026) in untreated patients, suggesting increased progression of myocardial amyloid deposition.

Conclusion

Treatment with tafamidis in patients with ATTR-CM results in significant improvements in functional capacity and cardiac biomarkers, and shows marked benefits in functional as well as structural imaging parameters compared with an untreated control cohort.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Pfizer Inc.

Recurrent heart failure hospitalizations in patients with preserved ejection fraction: predictors and outcome

Background

Heart failure with preserved ejection fraction (HFpEF) is the most common form of HF and its prevalence is approaching epidemic proportions. Current treatment strategies aim to improve clinical status and reduce mortality rates. Episodes of acute HF are one of the main reasons for hospitalization in people over 65 years; however, they have not been well studied in HFpEF patients yet.

Objectives

The aim of this study was to investigate the impact of recurrent HF hospitalizations on long-term outcomes and to find predictors for subsequent events.

Methods

Between December 2010 and December 2019, 422 patients with confirmed HFpEF were enrolled in this study and prospectively followed.

Results

During follow-up, 190 HFpEF patients (45%) experienced HF hospitalizations with a median frequency of 2 (IQR: 1–4). Those presenting with acute HF had higher body mass indices (p=0.018), worse performance in 6-minute walking tests (p<0.001), higher levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP, p<0.001) and, compared to stable patients, a larger proportion suffered from New York Heart Association functional class ≥ III (p<0.001). Furthermore, baseline left ventricular diastolic dysfunction (early mitral inflow velocity/early diastolic mitral annular velocity; p=0.002) as well as right ventricular afterload (pulmonary artery wedge pressure; p<0.001) were more pronounced in patients with acute deteriorations. Over the observation period 107 patients (25%) died. Kaplan-Meier curves revealed increasingly worse survival in patients with recurrent HF events (5-years survival: 1 HF event 66% vs ≥3 HF events 53%, p<0.001; Figure). Time to last hospitalization was a strong predictor of survival with an adjusted HR of 2.5 (95% CI 1.63–3.98; p<0.001) in multivariate Cox regression analysis. Predictors of recurrent HF hospitalization were 6-minute walking distance (OR: 0.07, CI 0.02–0.22; p=0.001), systolic pulmonary artery pressure (OR: 1.05, CI 1.03–1.07, p=0.001) and NT-pro BNP (OR: 4.92, CI: 2.68–9.04, p=0.001)

Conclusions

HFpEF patients experiencing recurrent HF hospitalizations have worse long-term outcome. Intensive efforts should be made to maintain HFpEF patients compensated over time.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Novartis

The Use of Bioelectrical Impedance to Assess Shelf-Life of Beef Longissimus Dorsi

ObjectivesTo evaluate quality attributes of beef longissimus dorsi (LD) during 15 d of simulated retail display using surface and internal bioelectrical impedance analysis (BIA) measurement techniques.Materials and MethodsThe experiment was designed as a split-plot with loin as the whole-plot and pairekd steaks as the sub-plot. Display day (DD) was treated as the sub-plot treatment. Postmortem age time (PM) and DD were treated as fixed effects. Beef strip loins (N = 18; IMPS #180), obtained from 3 commercial processors (PM = 27, 34, or 37 d), were fabricated into 12 2.54-cm thick steaks (N = 216). Steaks were subdivided into 6 consecutively cut pairs and pairs were randomly assigned to one of 6 display days: 0, 3, 6, 9, 12, and 15. For all pairs, one steak was allocated to microbiological analysis and pH and the paired steak for BIA, objective color assessment, proximate composition, and TBARS. Surface BIA (S-BIA) and internal BIA (I-BIA) assessment were compared. Steaks were packaged on styrofoam trays with a moisture absorbent pad, overwrapped with polyvinyl chloride film, and displayed under fluorescent lighting at 0–4°C in coffin-style retail cases.ResultsThere was a PM × DD interaction (P < 0.05) for S-BIA values. From d 0 to 12 of display, steaks aged 27 d had higher (P < 0.05) S-BIA values than steaks aged 34 and 37 d; however, on d 15 of display, steaks aged 34 d had 22% higher (P < 0.05) S-BIA values than steaks aged 37 d, but had similar (P > 0.05) values compared to steaks aged 27 d. There was no PM × DD interaction (P < 0.05) for I-BIA values; however, an effect on PM and DD was found (P < 0.05). Steaks aged 27 d were 17% higher for I-BIA values (P < 0.05) than 37 d, but similar (P > 0.05) to steaks aged 34 d. For all PM aging times, d 0 had the lowest (P < 0.05) I-BIA values among all display days with 81.44. D 3 was the second lowest (P < 0.05) and 8% higher than d 0 for I-BIA values. D 6 was 16% higher (P < 0.05) than d 3 but similar (P > 0.05) to d 9 and d 12. D 12 and D 15 were similar (P > 0.05). There was a DD × BIA method interaction (P < 0.05). On d 0, 3, and 6, BIA values were different (P < 0.05); however, after d 6 onward, BIA values were similar (P > 0.05). Covariance component was smaller in I-BIA than S-BIA. There were no PM × DD interactions (P > 0.05) for a* and b* values; however, there was an interaction for L* values. Postmortem aging had no effect (P > 0.05) on L*; however, an effect on a* and b* was found (P < 0.05). For APC populations, there was a PM × DD interaction (P < 0.05). No PM × DD interaction or PM effect (P > 0.05) were found for TBARS; however, there was a DD effect (P < 0.05). There was no PM day × DD interaction (P > 0.05) or PM day (P > 0.05) for moisture content. Display day (P < 0.05) had an effect on moisture content. Moderate negative correlations occurred between S-BIA values and a*, b*, and moisture content with –0.48, –0.46, and –0.46, respectively; and –0.51, –0.48, and –0.43, respectively, for I-BIA. Conversely, moderate positive correlation was found between S-BIA values and APC and TBARS with 0.34 and 0.53, respectively; and 0.29 and 0.51, respectively, for I-BIA.ConclusionI-BIA has potential for use to assess shelf-life of retail steaks and it was more precise than S-BIA; however, I-BIA may translocate bacteria into the muscle. Protein degradation and WHC should be evaluated to better understand BIA changes over time.

The ESC ACCA EAPCI EORP acute coronary syndrome ST-elevation myocardial infarction registry

Aims 

The Acute Cardiac Care Association (ACCA)–European Association of Percutaneous Coronary Intervention (EAPCI) Registry on ST-elevation myocardial infarction (STEMI) of the EurObservational programme (EORP) of the European Society of Cardiology (ESC) registry aimed to determine the current state of the use of reperfusion therapy in ESC member and ESC affiliated countries and the adherence to ESC STEMI guidelines in patients with STEMI.

Methods and results 

Between 1 January 2015 and 31 March 2018, a total of 11 462 patients admitted with an initial diagnosis of STEMI according to the 2012 ESC STEMI guidelines were enrolled. Individual patient data were collected across 196 centres and 29 countries. Among the centres, there were 136 percutaneous coronary intervention centres and 91 with cardiac surgery on-site. The majority of centres (129/196) were part of a STEMI network. The main objective of this study was to describe the demographic, clinical, and angiographic characteristics of patients with STEMI. Other objectives include to assess management patterns and in particular the current use of reperfusion therapies and to evaluate how recommendations of most recent STEMI European guidelines regarding reperfusion therapies and adjunctive pharmacological and non-pharmacological treatments are adopted in clinical practice and how their application can impact on patients’ outcomes. Patients will be followed for 1 year after admission.

Conclusion 

The ESC ACCA-EAPCI EORP ACS STEMI registry is an international registry of care and outcomes of patients hospitalized with STEMI. It will provide insights into the contemporary patient profile, management patterns, and 1-year outcome of patients with STEMI.

[Visualization of local cortical defects in Charcot foot using microcomputed tomography]

BACKGROUND

In the pathogenesis of diabetic neuropathic osteoarthropathy (Charcot's foot) fractures cause chronic destruction of soft tissue and bone structure. To improve an early diagnosis of Charcot foot, modern diagnostic imaging is mainly based on magnetic resonance imaging (MRI), for example in relation to the detection of cortical bone fractures.

OBJECTIVES

In this study we investigated the cortical microstructure in cases of Charcot foot with respect to fractures and porosity in order to visualize local cortical defects. This may substantiate recent efforts in a reclassification based on MRI.

MATERIAL AND METHODS

Using microcomputed tomography (microCT) we investigated bone parameters, such as cortical thickness and porosity in order to quantify the local metatarsal microstructure in cases of Charcot foot.

RESULTS

All bone samples showed a high degree of cortical porosity including pores that perforated the cortical bone. The data suggest that areas with reduced cortical thickness coincide with large cortical pores that may serve as initial points for fractures. Whether the detected microfractures are physiological or artefacts of preparation could not be determined.

CONCLUSION

By means of microCT we were able to visualize and quantify the extent of cortical porosity for the first time in high resolution. The data suggest that both cortical fractures and cortical porosity play an important role in the pathogenesis in cases of Charcot foot.

The MARS questionnaire: quality of life survey for acute rhinosinusitis

PURPOSE

Acute rhinosinusitis (ARS) significantly reduces the quality of life (QoL). While intensive research has focused on the QoL in patients with chronic rhinosinusitis, data regarding the impact of ARS on the QoL are relatively sparse. The aim of this study was to construct and validate a simple, reliable QoL questionnaire for ARS patients, which is also one of the priorities set for EPOS 2012.

METHODS

The questionnaire was constructed as follows: a review of literature, collection of symptoms as well as social and emotional consequences by a panel of ENT specialists and general practitioners, interviews with patients experiencing ARS, and a pre-test with another patient group. The questionnaire was validated by determining its internal reliability, discriminant validity, and responsiveness. The survey was given to 50 ARS patients at the time of diagnosis and again 14 days after treatment. The ARS diagnosis was established using the EPOS 12 criteria. The control group consisted of 50 medical students without any sinonasal symptoms.

RESULTS

We developed a 13-item questionnaire, called the MARS (Measurement of Acute Rhinosinusitis). Cronbach's alpha was determined to be 0.679. The two-tailed t-test showed a statistically significant difference between the patient group and the control group (p = 0.0000). The SRM coefficient was 1.781.

CONCLUSION

The MARS questionnaire is a QoL instrument developed and validated especially for patients with ARS. This survey demonstrated good internal consistency and excellent discriminant validity, responsiveness, and feasibility for use in daily clinical practice and research.

The effect of a flexible pylon system on functional mobility of transtibial amputees. A prospective randomized study

BACKGROUND

Prosthetic component selection strongly influences the functional mobility of transtibial amputees. Until now, little attention has been paid to the connection between the prosthetic socket and the foot component.

AIM AND DESIGN

Aim of this study was to compare a novel flexible with a conventional rigid pylon system in a prospective randomized trial in transtibial amputees to determine effects on gait and mobility.

SETTING

The study was performed in a rehabilitation centre for geriatric amputees.

POPULATION

Twenty-eight geriatric unilateral transtibial amputees (8 female, 20 male) with low degree of mobility were included.

METHODS

At admission to the rehabilitation centre objective and subjective parameters were assessed including demographic data and levels of daily activity using standardized questionnaires. Three months after prosthetic fitting a follow-up was performed and additional parameters such as walking speed, step length and vertical ground reaction forces were examined using a dynamic gait analysis.

RESULTS

The study revealed a significant improvement in step length (P=0.03), in using mobility aids (P=0.04) and benefits concerning the self-selected gait speed, the mobility and gait disorders using the flexible device.

CONCLUSION

The results demonstrate advantages for the flexible system, resulting in a positive effect on the patient's gait accomplishments in a geriatric population.

CLINICAL REHABILITATION IMPACT

The advantages of the dynamic pylon may improve clinical rehabilitation, especially for geriatric patients with vascular disorders, as it provides comfort and better prosthetic performance during gait as a short-term benefit and thus gives a better quality of life in the long-term.

Evaluation of Computed Tomography Data from Fibre Reinforced Polymers to Determine Fibre Length Distribution

Sub-μm computed tomography (sub-μm-CT) was used to determine the fibre orientation and fibre length distribution in long glass fibre filled polypropylene. For data evaluation two different concepts based on the application of a sequence of different filters were applied. The first concept is based on segmentation by binarisation using a global threshold, followed by a detailed analysis of regions where fibres are touching. The second concept is based on analysis of the original gray value image. For each voxel the local fibre orientation is determined by calculating the Hessian Matrix and analysing its Eigen values.

The effectivity of the two data analysis concepts in determining orientation and length was investigated. For this purpose the algorithms were applied to specimens with four different levels of fibre content: 1, 5, 10 and 30% by weight. To quantify the level of error in fibre determination, a minimum and average probability for correct fibre determination were estimated.

The results show a strong dependence of the level of error on the fibre content. Whilst the determination of fibre orientation is not significantly affected, determination of fibre length distribution is significantly influenced by fibre content. For samples with fibre content above 5%, concept 1 does not produce correct representations of all fibres. In particular, problems arise if the fibres are touching. Concept 2 delivers much better results and represents most of the fibres correctly even at higher fibre content levels and for touching fibres. This was proven by using artificial CT-data sets generated by CT-simulation and by systematic comparisons. A practical application of the CT-evaluation pipeline is presented for glass fibre reinforced rings produced by injection-moulding and extrusion. For both samples the orientation tensors are calculated and the orientations of the fibres are visualized in three dimensions by colour coding.

Production of aromatic green gasoline additives via catalytic pyrolysis of acidulated peanut oil soap stock

Catalytic pyrolysis was used to generate gasoline-compatible fuel from peanut oil soap stock (PSS), a high free fatty acid feedstock, using a fixed-bed reactor at temperatures between 450 and 550°C with a zeolite catalyst (HZSM-5). PSS fed at 81 gh(-1) along with 100 mL min(-1) inert gas was passed across a 15 g catalyst bed (WHSV=5.4h(-1), gas phase residence time=34s). Results indicate that fuel properties of PSS including viscosity, heating value, and O:C ratio were improved significantly. For PSS processed at 500°C, viscosity was reduced from 59.6 to 0.9 mm(2)s(-1), heating value was increased from 35.8 to 39.3 MJL(-1), and the O:C ratio was reduced from 0.07 to 0.02. Aromatic gasoline components (e.g., BTEX), were formed in concentrations as high as 94% (v/v) in catalytically-cracked PSS with yields ranging from 22% to 35% (v/v of PSS feed).

Occult thyroid carcinoma

Some medical definitions remain the same for many years, others change due to the progress in the diagnostic tools, which are able to distinguish markers and symptoms until then undetectable. Occult thyroid carcinoma is a general term indicating clinically different situations, whereas the incidentally detected papillary thyroid microcarcinoma is the most important from the clinical point of view. It is fundamental, for therapeutic management, to determine biological parameters which would define a small group of papillary thyroid microcarcinomas with aggressive biological behaviour. The most promising genetic and molecular markers for papillary thyroid carcinoma risk stratification are discussed in this review. Preoperative evaluation of these markers, obtained through analysis of ultrasonography-guided fine needle biopsy specimens of papillary thyroid microcarcinoma, could be very valuable in guiding treatment of this type of cancer.

Implantable loop recorder in unexplained syncope: classification, mechanism, transient loss of consciousness and role of major depressive disorder in patients with and without structural heart disease

OBJECTIVE

To stratify mechanisms and predictors of unexplained syncope documented by an implantable loop recorder (ILR) in patients with and without structural heart disease (SHD).

DESIGN AND SETTING

Prospective study in consecutive patients of a university cardiac centre.

PATIENTS AND METHODS

An ILR was implanted in 70 patients (34 male/36 female, aged 55 (17) years) in whom syncope remained unexplained after thorough testing. SHD was present in 33 patients (ischaemic cardiomyopathy in 16, dilated cardiomyopathy in 9 and hypertrophic cardiomyopathy in 8) and absent in 37 patients (mean (SD) left ventricular ejection fraction 46 (4)% vs 61 (7)%, respectively).

RESULTS

A syncopal recurrence occurred during 16 (8) months in 30 patients (91%) with SHD and in 30 patients (81%) without SHD. Fifteen patients (45%) versus 19 patients (51%), respectively, had an ILR-documented arrhythmia at the time of recurrence which led to specific treatment. The remaining 15 patients (45%) with SHD and 11 patients (30%) without SHD had normal sinus rhythm at the time of the recurrence. On stepwise multivariate analysis only major depressive disorder was predictive for early recurrence during ILR follow-up (p = 0.01, hazard ratio = 3.35, 95% CI 1.1 to 7.1). Fifty seven per cent of patients with major depressive disorder had sinus rhythm during recurrence compared with 31% of patients without the disorder (p = 0.01). Conversely, no patient with major depressive disorder had asystole compared with 33% without (p<0.001).

CONCLUSIONS

The presence of SHD has little predictive value for the occurrence or type of arrhythmia in patients with unexplained syncope. Patients with major depressive disorder are prone to early recurrence of symptoms and have no evidence of arrhythmia in most cases. The ILR leads to specific treatment in half of all patients.

The contribution of MRI to the diagnosis of diffuse meningeal lesions

We analysed MRI findings in patients in whom a diffuse abnormality of the meninges was revealed by MRI. We looked at T1 and T2-weighted spin-echo or fast spin-echo images and contrast-enhanced T1-weighted images. There were 15 patients with abnormalities on MRI, clinically suspected in ten. Four had meningoencephalitis, one meningeal and subcortical sarcoidosis nodules, four meningeal malignancies--one disseminated oligodendroglioma, one with meningeal infiltration around an adenocarcinoma, three meningeal infiltration by a haematological malignancy, and one a chronic subdural haematoma without a history of injury. We excluded patients with primary meningeal tumours and typical injury-related meningeal bleeding. The relatively small number of patients is due to both the infrequency of diffuse meningeal disease and to the low frequency of suspected meningeal pathology as an indication for MRI. The latter's diagnostic contribution is greatest in infectious disease and neoplastic infiltration, and less obvious in haematological malignancies. Contrast-enhanced T1-weighted images are most useful.

[Spindle cell and cuboidal renal cell carcinoma (loopoma). 10 case reports]

BACKGROUND

Current classification systems of neoplasms arising from renal parenchyma distinguish 5 categories of renal cell carcinoma (RCC), i.e. conventional RCC, papillary RCC, chromophobe RCC, collecting duct/medullary RCC and unclassified RCC. We present 13 cases of unusual and unclassified spindle and cuboidal renal cell carcinomas.

METHODS AND RESULTS

The studied group consisted of 13 patients (7 men and 6 women). They ranged in age from 22 to 65 years (mean 57.3). Generally, the tumours were well circumscribed and confined to the kidney, whitish to grey on section with a diameter 4.5-13 cm (mean 8.6 cm). One patient was investigated for loin pain and nocturia. Three patients had staghorn nephrolithiasis and vague sonographic findings in renal parenchyma. In one patient the renal tumour was found when examined on follow-up examination for prostatic adenocarcinoma. None of our patients was known to have elevated levels of parathyroid hormone due to hyperplasia, adenoma or carcinoma of the parathyroid gland. Clinical follow-up of the patients ranged from 9 months to 8 years (mean 2.3 years). Microscopically, the tumours were composed of two main populations of cells: flattened, spindle cells with sparse cytoplasm and small cuboidal cells with clear to light eosinophilic cytoplasm. Eight patients are currently well without signs of recurrence or metastasis, one had metastasis in the regional lymph node at the time of nephrectomy, one died of unrelated cause, and three were lost to follow-up.

CONCLUSIONS

We present 13 cases of unclassified RCC. Our cases were histologically, immunohistochemically and ultrastructurally similar to the hitherto reported case reports of this variant of RCC. It is obvious, that that variant of RCC should be recognised as a new subtype of RCC.

Unexplained syncope in patients with structural heart disease and no documented ventricular arrhythmias: value of electrophysiologically guided implantable cardioverter defibrillator therapy

AIMS

To evaluate electrophysiologically guided implantable cardioverter defibrillator (ICD) therapy in patients with syncope, structural heart disease and no documented sustained ventricular tachycardia (sVT).

METHODS AND RESULTS

Programmed ventricular stimulation (PVS) was performed in 52 patients (age 62+/-10 years): 40 patients had ischaemic and 12 patients had idiopathic dilated cardiomyopathy. On PVS sVT and ventricular fibrillation were induced in seven and four patients, respectively, and two patients spontaneously experienced symptomatic sVT. These patients received an ICD (ICD group, n=13). Non-inducible patients were left on conventional therapy (non-ICD group, n=39). During 5+/-2.8 years five ICD patients received therapies, all appropriate. There were seven non-sudden deaths and overall survival analysis revealed no significant difference. Recurrent syncope occurred in five ICD and four non-ICD patients and did not correlate well with sVT. The positive and negative predictive values of PVS for tachyarrhythmias or sudden death were 36 and 98%, respectively.

CONCLUSION

Syncope per se does not necessarily herald a bad prognosis. PVS identifies high-risk patients. Induction of ventricular fibrillation with double or triple extrastimuli is of limited value. Patients with poor left ventricular function and bad clinical condition benefit most from an ICD. Syncope and sVT are not necessarily correlated during follow-up, which may merit consideration.

[Urologic complications in pelvic injuries]

OBJECTIVE

Urological complications of pelvic fractures include in particular rupture of the urinary bladder (RUB), injury of the posterior urethra (IPU) and erectile dysfunction (ED). The authors present their own group of patients and in particular the diagnostic and therapeutic algorithm in IPU.

MATERIAL AND METHODS

In the Plzen Faculty Hospital in 1/1998 to 8/2002 a total of 19 patients were treated with serious urological complications of pelvic fractures--9x RUB, 11x IPU (once with RUB). RUB was in one instance intraperitoneal, in the remainder extraperitoneal.

RESULTS

IPU was without dislocation 6x, with dislocation 5x. Primary "realignment" of the urethra was made in 6 patients (in dislocations and in concurrent rupture of the bladder). In the remaining 5 an epicystostomy was established. In 4 after an interval of 3 months a posterior resection urethroplasty was made because of a distraction defect. One patient with a distraction defect was referred to the urological department of the catchment area and in another patient after-treatment is planned. Severe ED developed in 6 IPU of 10, always in dislocations of the urethra. In one patient we lack information on erections.

CONCLUSION

When IPU is suspected (urethrorhagia), dislocation of the prostate on examination p.r.) ascendent urethrography and IVU are essential. Do not catheterize before completed examination. Then needle epicystostomy is performed, in major dislocations of the urinary bladder or in associated injuries primary "realignment" of the urethra open on a catheter or endoscopically. In distraction defects after 12 weeks a posterior resection plastic operation follows.

Boundary element method volume conductor models for EEG source reconstruction

OBJECTIVES

The boundary element method (BEM) approximates the different compartments of volume conductor models by closed triangle meshes with a limited number of nodes. The shielding effect of the weakly conducting skull layer of the human head leads to decreasing potential gradients from the inside to the outside. Thus, there may be an optimum distribution of nodes to the compartments for a given number of nodes corresponding to a fixed computational effort, resulting in improved accuracy as compared to standard uniform distributions.

METHODS

Spherical and realistically shaped surfaces are approximated by 500, 1000, 2000, and 3000 nodes, each leading to BEM models with 1500-9000 nodes in total. Electrodes are placed on extended 10/20-system positions. Potential distributions of test-dipoles at 4000 random positions within the innermost compartment are calculated. Dipoles are then fitted using 192 different models to find the optimum node distribution.

RESULTS

Fitted dipole positions for all BEM models are evaluated to show the dependency of the averaged and maximum localization errors on their node distributions. Dipoles close to the innermost boundary exhibit the largest localization errors, which mainly depend on the refinement of this compartment's triangle mesh.

CONCLUSIONS

More than 500 nodes per compartment are needed for reliable BEM models. For a state-of-the-art model consisting of 6000 nodes overall, the best model consists of 3000, 2000, and 1000 nodes from the inside to the outside.

Enhancements in the accuracy of the center of pressure (COP) determined with piezoelectric force plates are dependent on the load distribution

Errors up to +/- 30 mm in determining the COP with piezoelectric force plates have been reported in the literature. To compensate for these errors, correction formulas were proposed, based on measurements with single point loads. In this paper, it will be shown that the errors in the COP depend on the load distribution. Two examples are presented: (1) simulated balance study, and (2) different pressure patterns during walking. Accurate corrections can only be made for forces distributed over a small area. Errors are expected to be overcompensated if there are only a few pressure peaks separated by large distances. These errors can be as large as the statistical errors (5.8 +/- 3.7 mm) after compensation. For certain situations, it is probably better not to use correction formulas.

Inhaled nitric oxide reduces pulmonary vascular resistance more than prostaglandin E(1) during heart transplantation

Heart transplantation in patients with increased pulmonary vascular resistance is often associated with postbypass right heart failure. We therefore compared the abilities of prostaglandin E(1) (PGE(1)) and inhaled nitric oxide to reduce pulmonary vascular resistance during heart transplantation. Patients undergoing orthotopic heart transplantation for congestive heart failure were randomly assigned to either a PGE(1) infusion at a rate of 8 ng. kg. (-1)min(-1) starting 10 min before weaning from cardiopulmonary bypass (CPB) (n = 34) or inhalation of 4 ppm nitric oxide starting just before weaning from CPB (n = 34). Both treatments were increased stepwise, if necessary, and were stopped 6 h postoperatively. Hemodynamic values were recorded after the induction of anesthesia, 10 and 30 min after weaning from CPB, and 1 h and 6 h postoperatively. Immediately after weaning from CPB, pulmonary vascular resistance was nearly halved in the nitric oxide group but reduced by only 10% in the PGE(1) group. Pulmonary artery pressure was decreased approximately 30% during nitric oxide inhalation, but only approximately 16% during the PGE(1) infusion. Six hours after surgery, pulmonary vascular resistance and pulmonary artery pressure were similar in the two groups. The ratio between pulmonary vascular resistance and systemic vascular resistance was significantly less in the nitric oxide patients at all postbypass times. In contrast, the pulmonary-to-systemic vascular resistance ratio increased approximately 30% in the patients given PGE(1). Cardiac output, heart rate, mean arterial pressure, right atrial pressure, and pulmonary wedge pressure did not differ between the groups. Weaning from CPB was successful in all patients assigned to nitric oxide inhalation; in contrast, weaning failed in six patients assigned to PGE(1) (P = 0.03).

IMPLICATIONS

Nitric oxide inhalation selectively reduces pulmonary vascular resistance and pulmonary artery pressure immediately after heart transplantation which facilitates weaning from cardiopulmonary bypass.

[Nonlinear dynamics, chaos theory and wavelet analysis of the heart]

Over the past years, techniques of nonlinear dynamics have gained increasing attention in cardiology. This kind of partly interdisciplinary research is supposed to provide a better understanding of cardiac disease, especially in the field of tachyarrhythmia. This article intends to introduce the principles of diagnostic procedures in terms of nonlinear dynamics, chaos theory and stochastic processes related to cardiology. An introduction to a new technique of wavelet analysis is given, and possible applications in the quantitative classification of high-risk patients for sudden cardiac death are discussed.

Efficacy of two methods for reducing postbypass afterdrop

BACKGROUND

Afterdrop, defined as the precipitous reduction in core temperature after cardiopulmonary bypass, results from redistribution of body heat to inadequately warmed peripheral tissues. The authors tested two methods of ameliorating afterdrop: (1) forced-air warming of peripheral tissues and (2) nitroprusside-induced vasodilation.

METHODS

Patients were cooled during cardiopulmonary bypass to approximately 32 degrees C and subsequently rewarmed to a nasopharyngeal temperature near 37 degrees C and a rectal temperature near 36 degrees C. Patients in the forced-air protocol (n = 20) were assigned randomly to forced-air warming or passive insulation on the legs. Active heating started with rewarming while undergoing bypass and was continued for the remainder of surgery. Patients in the nitroprusside protocol (n = 30) were assigned randomly to either a control group or sodium nitroprusside administration. Pump flow during rewarming was maintained at 2.5 l x m(-2) x min(-1) in the control patients and at 3.0 l x m(-2) x min(-1) in those assigned to sodium nitroprusside. Sodium nitroprusside was titrated to maintain a mean arterial pressure near 60 mm Hg. In all cases, a nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 18 intramuscular needle thermocouples, nine skin temperatures, and "deep" hand and foot temperature.

RESULTS

In patients warmed with forced air, peripheral tissue temperature was higher at the end of warming and remained higher until the end of surgery. The core temperature afterdrop was reduced from 1.2+/-0.2 degrees C to 0.5+/-0.2 degrees C by forced-air warming. The duration of afterdrop also was reduced, from 50+/-11 to 27+/-14 min. In the nitroprusside group, a rectal temperature of 36 degrees C was reached after 30+/-7 min of rewarming. This was only slightly faster than the 40+/-13 min necessary in the control group. The afterdrop was 0.8+/-0.3 degrees C with nitroprusside and lasted 34+/-10 min which was similar to the 1.1+/-0.3 degrees C afterdrop that lasted 44+/-13 min in the control group.

CONCLUSIONS

Cutaneous warming reduced the core temperature afterdrop by 60%. However, heat-balance data indicate that this reduction resulted primarily because forced-air heating prevented the typical decrease in body heat content after discontinuation of bypass, rather than by reducing redistribution. Nitroprusside administration slightly increased peripheral tissue temperature and heat content at the end of rewarming. However, the core-to-peripheral temperature gradient was low in both groups. Consequently, there was little redistribution in either case.

Parameters influencing the accuracy of the point of force application determined with piezoelectric force plates

Errors up to +/- 30 mm in determining the point of force application with piezoelectric force plates have been reported in the literature (Kistler, 1984. Multicomponent Measuring Force Plate for Biomechanics and Industry. Kistler, Switzerland; Bobbert and Schamhardt, 1990. Journal of Biomechanics 23, 705-710; Sommer et al., 1997. Proceedings of the XVI th I.S.B. Congress). To explain the main factors influencing the systematic errors the force plate system is modeled as a two-dimensional beam structure. By this model it is strongly indicated that the cause for the errors in determining the point of force application are bending moments in the measurement posts. The main parameters influencing the shape and magnitude of the error function are the ratios between the bending stiffness of the plate and the bending and compressive stiffnesses of the measurement posts. In the current design it is therefore not possible to eliminate the cause for the errors by changing the constructive parameters. By comparing the error functions derived with the beam model to the correction formulas given in the literature an improved algorithm is proposed. This paper shall help biomechanists in understanding the basic concepts of determining the point of force application with force plates and in constructing custom-made force plates for specific applications.

Tissue heat content and distribution during and after cardiopulmonary bypass at 17 degrees C

We measured afterdrop and peripheral tissue temperature distribution in eight patients cooled to approximately 17 degrees C during cardiopulmonary bypass and subsequently rewarmed to 36.5 degrees C. A nasopharyngeal probe evaluated trunk and head temperature and heat content. Peripheral tissue temperature (arm and leg temperature) and heat content were estimated using fourth-order regressions and integration over volume from 30 tissue and skin temperatures. Peripheral tissue temperature decreased to 19.7+/-0.9 degrees C during bypass and subsequently increased to 34.3+/-0.7 degrees C during 104+/-18 min of rewarming. The core-to-peripheral tissue temperature gradient was -5.9+/-0.9 degrees C at the end of cooling and 4.7+/-1.5 degrees C at the end of rewarming. The core-temperature afterdrop was 2.2+/-0.4 degrees C and lasted 89+/-15 min. It was associated with 1.1+/-0.7 degrees C peripheral warming. At the end of cooling, temperatures at the center of the upper and lower thigh were (respectively) 8.0+/-5.2 degrees C and 7.3+/-4.2 degrees C cooler than skin temperature. On completion of rewarming, tissue at the center of the upper and lower thigh were (respectively) 7.0+/-2.2 degrees C and 6.4+/-2.3 degrees C warmer than the skin. When estimated systemic heat loss was included in the calculation, redistribution accounted for 73% of the afterdrop, which is similar to the contribution observed previously in nonsurgical volunteers.

IMPLICATIONS

Temperature afterdrop after bypass at 17 degrees C was 2.2+/-0.4 degrees C, with approximately 73% of the decrease in core temperature resulting from core-to-peripheral redistribution of body heat. Cooling and rewarming were associated with large radial tissue temperature gradients in the thigh.