Hochdurchsatz Analyse in den Biowissenschaften durch die Nutzung von Service Oriented Clustering (Proliferating High Throughput Analysis in Life Science by using Service Oriented Clustering)

Obwohl man Cluster erfolgreich für Aufgaben wie Protein Identifikation und multiple alignment einsetzt, sind sie dennoch selten Teil des Laboralltags. Hauptgrund ist die schlechte Integrationsfähigkeit aktueller Lösungen in den Arbeitsablauf. Das Konzept Dienste Orientierter Cluster soll dieses Problem beheben.

Carryover of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from soil to plants

Within the scope of a joint project to study soil-to-plant carryover of polyfluorinated compounds (PFCs), five cultivated plants (spring wheat, oats, potatoes, maize, and perennial ryegrass) were sown or planted in Mitscherlich pots. Six variants per species were used, each with a different concentration level of PFOA and PFOS (from 0.25 to 50 mg/kg as aqueous solution) to detect possible concentration dependence in the transfer of these two PFCs from soil to plant. PFOA and PFOS were detected by liquid chromatography-tandem mass spectrometry after appropriate sample preparation (partial drying, mincing, homogenizing, extraction). Since PFOA and PFOS presently represent the most widely studied PFCs, they are classified as "leading compounds." The results show that concentrations of PFOA/PFOS in the plants vary greatly, depending on the concentrations applied to the soil. PFOA values were higher than PFOS values in all plants except potatoes, in which these differences could be quite substantial. From the results presented here it can be seen that uptake and storage are much more intensive in the vegetative portion of the plant than relocation in the storage organs. This is particularly evident from the the comparison of concentrations found in the grain and ear and those in the straw or rest of the plant in spring wheat, oats, and maize. Transfer from "soil to crops" provides a possible explanation for the presence of PFCs in foodstuffs and in human body fluids such as blood, plasma, serum, or breast milk. The aim of the present study was to determine whether a statistically significant, concentration-dependent carryover of PFOA and PFOS in crop plants can take place, which would provide a potential entrance point for these substances into the food chain.

[Nephrectomy for renal cell carcinoma in combination with simultaneous major surgical procedures in a primary surgical hospital]

BACKGROUND

Renal cell carcinoma appears in a certain percentage of patients combined with other abdominal disorders. Their simultaneous operative treatment is not widely reported in the literature. In this retrospective study, we have looked for the advantages of simultaneous operative procedures and whether these can be done safely in a primary surgical hospital.

PATIENTS AND METHODS

From 1991-2007 we reviewed 14 cases. We compared the results with those of patients who underwent nephrectomy in our urological department and from the actual literature.

RESULTS

The overall operation times in the combined surgical and the urological group were nearly identical (135 versus 131 min). The postoperative hospital stay was slightly longer in the combined surgical group (16.6 versus 13.3 days). The morbidity was higher in the combined surgical group. These patients had also a higher comorbidity.

CONCLUSIONS

We can see clear advantages in simultaneous operations for renal cell carcinoma and other major surgical procedures in the abdomen. This study shows that an experienced surgeon in a primary surgical hospital can perform nephrectomy with simultaneous major abdominal procedures with advantages for the patient as far as operation time and hospital stay are concerned.

Biomarker discovery in MALDI-TOF serum protein profiles using discrete wavelet transformation

MOTIVATION

Automatic classification of high-resolution mass spectrometry proteomic data has increasing potential in the early diagnosis of cancer. We propose a new procedure of biomarker discovery in serum protein profiles based on: (i) discrete wavelet transformation of the spectra; (ii) selection of discriminative wavelet coefficients by a statistical test and (iii) building and evaluating a support vector machine classifier by double cross-validation with attention to the generalizability of the results. In addition to the evaluation results (total recognition rate, sensitivity and specificity), the procedure provides the biomarker patterns, i.e. the parts of spectra which discriminate cancer and control individuals. The evaluation was performed on matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) serum protein profiles of 66 colorectal cancer patients and 50 controls.

RESULTS

Our procedure provided a high recognition rate (97.3%), sensitivity (98.4%) and specificity (95.8%). The extracted biomarker patterns mostly represent the peaks expressing mean differences between the cancer and control spectra. However, we showed that the discriminative power of a peak is not simply expressed by its mean height and cannot be derived by comparison of the mean spectra. The obtained classifiers have high generalization power as measured by the number of support vectors. This prevents overfitting and contributes to the reproducibility of the results, which is required to find biomarkers differentiating cancer patients from healthy individuals.

AVAILABILITY

The data and scripts used in this study are available at http://www.math.uni-bremen.de/~theodore/MALDIDWT.

[Unusual cause of pulmonary embolism]

Aneurysms of popliteal veins are a rare but silent danger that may involve pulmonary embolism. This case report is of a 63-year-old woman with a venous aneurysm of the left popliteal vein who suffered pulmonary embolism twice during treatment with phenprocoumon. Three days after resection she suffered an embolism of the left popliteal vein. Follow-up at 12 months with duplex showed no signs of thrombosis.

Hyphenated tools for phospholipidomics

The analysis of intact and underivatised lipids in body fluids as well as in cell and tissue extracts is of utmost importance in the field of early diagnosis. Therefore, fast, reliable, and automated analytical methods are needed to detect known as well as unknown species. The combination of solid phase extraction, high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy are best at meeting this challenge. Herein, we show a workflow for the reliable analysis of individual components in phosphatidylethanolamine extracts. The limitations and advantages of the individual methods are discussed.

Transcatheter closure of postinfarction ventricular septal defects

Postinfarction ventricular septal defect (VSD) is a rare but fatal complication after myocardial infarction. Surgery for postinfarction VSD is considered the gold standard. However, it is associated with high morbidity and mortality, patient discomfort, need of cardiopulmonary bypass, sternotomy, and skin scarring. As a consequence, less invasive interventional techniques have been developed for postinfarction VSD closure. The current review focuses on patient selection, techniques, results, potential complications and outcome of percutaneous postinfarction closure.

Even-electron ions: a systematic study of the neutral species lost in the dissociation of quasi-molecular ions

The collision-induced dissociations of the even-electron [M + H](+) and/or [M - H](-) ions of 121 model compounds (mainly small aromatic compounds with one to three functional groups) ionized by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) have been studied using an ion trap instrument, and the results are compared with the literature data. While some functional groups (such as COOH, COOCH(3), SO(3)H in the negative ion mode, or NO(2) in both the positive and negative ion modes) generally promote the loss of neutrals that are characteristic as well as specific, other functional groups (such as COOH in the positive ion mode) give rise to the loss of neutrals that are characteristic, but not specific. Finally, functional groups such as OH and NH(2) in aromatic compounds do not lead to the loss of a neutral that reflects the presence of these substituents. In general, the dissociation of [M + H](+) and [M - H](-) ions generated from aliphatic compounds or compounds containing an aliphatic moiety obeys the even-electron rule (loss of a molecule), but deviations from this rule (loss of a radical) are sometimes observed for aromatic compounds, in particular for nitroaromatic compounds. Thermochemical data and ab initio calculations at the CBS-QB3 level of theory provide an explanation for these exceptions. When comparing the dissociation behaviour of the even-electron [M + H](+) and/or [M - H](-) ions (generated by ESI or APCI) with that of the corresponding odd-electron [M](+) ions (generated by electron ionization, EI), three cases may be distinguished: (1) the dissociation of the two ionic species differs completely; (2) the dissociation involves the loss of a common neutral, yielding product ions differing in mass by one Da, or (3) the dissociations lead to a common product ion.

Characterization of Sphingomyelins in Lipid Extracts Using a HPLC-MS-Offline-NMR Method

Sphingomyelins were characterized using a combination of a novel isocratic reversed-phase HPLC method with electrospray time-of-flight mass spectrometric detection and optional online MS/MS. The constitution of the sphingomyelins is determined by MS/MS experiments. Baseline separation of 17 compounds of a bovine brain extract (2 main compounds and 15 minor or trace compounds) was achieved with a mobile phase consisting of methanol, 2-propanol, THF, and water on a RP-18-phenyl column. In parallel, the HPLC fraction were sampled to a 600-MHz NMR spectrometer to acquire 1D and 2D NMR spectra and to elucidate the molecular structure of individual sphingomyelin components.

Automated reprocessing pipeline for searching heterogeneous mass spectrometric data of the HUPO Brain Proteome Project pilot phase

The newly available techniques for sensitive proteome analysis and the resulting amount of data require a new bioinformatics focus on automatic methods for spectrum reprocessing and peptide/protein validation. Manual validation of results in such studies is not feasible and objective enough for quality relevant interpretation. The necessity for tools enabling an automatic quality control is, therefore, important to produce reliable and comparable data in such big consortia as the Human Proteome Organization Brain Proteome Project. Standards and well-defined processing pipelines are important for these consortia. We show a way for choosing the right database model, through collecting data, processing these with a decoy database and end up with a quality controlled protein list merged from several search engines, including a known false-positive rate.

HUPO Brain Proteome Project: Summary of the pilot phase and introduction of a comprehensive data reprocessing strategy

The Human Proteome Organisation (HUPO) initiated several projects focusing on the proteome analysis of distinct human organs. The Brain Proteome Project (BPP) is the initiative dedicated to the brain, its development and correlated diseases. Two pilot studies have been performed aiming at the comparison of techniques, laboratories and approaches. With the help of the results gained, objective data submission, storage and reprocessing workflow have been established. The biological relevance of the data will be drawn from the inter-laboratory comparisons as well as from the re-calculation of all data sets submitted by the different groups. In the following, results of the single groups as well as the centralised reprocessing effort will be summarised and compared, showing the added value of this concerted work.

Gaining knowledge from previously unexplained spectra-application of the PTM-Explorer software to detect PTM in HUPO BPP MS/MS data

A novel software tool named PTM-Explorer has been applied to LC-MS/MS datasets acquired within the Human Proteome Organisation (HUPO) Brain Proteome Project (BPP). PTM-Explorer enables automatic identification of peptide MS/MS spectra that were not explained in typical sequence database searches. The main focus was detection of PTMs, but PTM-Explorer detects also unspecific peptide cleavage, mass measurement errors, experimental modifications, amino acid substitutions, transpeptidation products and unknown mass shifts. To avoid a combinatorial problem the search is restricted to a set of selected protein sequences, which stem from previous protein identifications using a common sequence database search. Prior to application to the HUPO BPP data, PTM-Explorer was evaluated on excellently manually characterized and evaluated LC-MS/MS data sets from Alpha-A-Crystallin gel spots obtained from mouse eye lens. Besides various PTMs including phosphorylation, a wealth of experimental modifications and unspecific cleavage products were successfully detected, completing the primary structure information of the measured proteins. Our results indicate that a large amount of MS/MS spectra that currently remain unidentified in standard database searches contain valuable information that can only be elucidated using suitable software tools.

[Peri-interventional risk in 1,384 cardiac catheterizations in patients aged 80 years or older]

BACKGROUND AND OBJECTIVE

Because of the rising life expectancy in the industrialized countries, ever more cardiac catheterizations are performed in patients aged 80 years or older. Little is known about the incidence of peri-interventional events in this age group.

PATIENTS AND METHODS

Between January 1996 and September 2000, a total of 1,085 patients of that age (mean 82.6 +/- 2.6 years) underwent cardiac catheterization and intervention (3% of a total of 43,517 cardiac catheterizations).

RESULTS

827 patients (77%) had significant coronary artery stenoses. 373 of them (45%) were treated with balloon angioplasty, with or without stenting, and 331 (40%) underwent aortocoronary bypass procedures. 31 patients died while in hospital, 17 of them having been in cardiogenic shock on admission. Peri-interventional events, including damage to artery at the site of catheter entry occurred in 2.1% of patients undergoing diagnostic cardiac catheterization and in 11.6% in connection with a percutaneous interventional procedure.

CONCLUSION

Both cardiac catheterization and interventional procedures can be done with a justifiable risk in patients aged 80 years or older. These cardiac investigations/interventions should not be withheld in this group of patients for reasons of age.

A genome-wide scan for attention-deficit/hyperactivity disorder in 155 German sib-pairs

Three groups have previously performed genome scans in attention-deficit/hyperactivity disorder (ADHD); linkage to chromosome 5p13 was detected in all of the respective studies. In the current study, we performed a whole-genome scan with 102 German families with two or more offspring who currently fulfilled the diagnostic criteria for ADHD. Including subsequent fine mapping on chromosome 5p, a total of 523 markers were genotyped. The highest nonparametric multipoint LOD score of 2.59 (empirical genome-wide significance 0.1) was obtained for chromosome 5p at 17 cM (according to the Marshfield map). Subsequent analyses revealed (a) a higher LOD score of 3.37 at 39 cM for a quantitative severity score based on symptoms of inattention than for hyperactivity/impulsivity (LOD score of 1.11 at 59 cM), and (b) an HLOD of 4.75 (empirical genome-wide significance 0.001) based on a parametric model assuming dominant inheritance. The locus of the solute carrier 6A3 (SLC6A3; dopamine transporter 1; DAT1) localizes to 5p15.33; the gene has repeatedly been implicated in the etiology of ADHD. However, in our sample the DAT1 VNTR did not show association with ADHD. We additionally identified nominal evidence for linkage to chromosomes 6q, 7p, 9q, 11 q, 12q and 17p, which had also been identified in previous scans. Despite differences in ethnicity, ascertainment and phenotyping schemes, linkage results in ADHD appear remarkably consistent.

5th HUPO BPP Bioinformatics Meeting at the European Bioinformatics Institute in Hinxton, UK - Setting the Analysis Frame

The Bioinformatics Committee of the HUPO Brain Proteome Project (HUPO BPP) meets regularly to execute the post-lab analyses of the data produced in the HUPO BPP pilot studies. On July 7, 2005 the members came together for the 5th time at the European Bioinformatics Institute (EBI) in Hinxton, UK, hosted by Rolf Apweiler. As a main result, the parameter set of the semi-automated data re-analysis of MS/MS spectra has been elaborated and the subsequent work steps have been defined.

Towards data management of the HUPO Human Brain Proteome Project pilot phase

The pilot phase of the Human Brain Proteome Project as a part of the Human Proteome Organisation has just been started. In two pilot studies, 18 different laboratories are analyzing mouse brains of three age stages and human brain autopsy versus biopsy material, respectively. The overall aim is to elucidate the portfolio of available techniques as well as to elaborate common standards. As a first step, it was decided to use the common bioinformatics platform ProteinScape that was introduced to the participating groups in a two day course in Bochum, Germany.

Structure elucidation of phase II metabolites by tandem mass spectrometry: an overview

The present paper provides a summary of the collision-induced dissociation of protonated and deprotonated phase II metabolites of drugs and pesticides. This overview is based on published literature and unpublished data from the authors. In particular, glutathione conjugates and their biotransformation products are discussed in detail. In addition, the fragmentation of the major classes of conjugates, i.e. glucuronides, glucosides, malonylglucosides, sulfates, acetates, methyl and glycine conjugates, is reported. Collision-induced dissociation, as studied by tandem mass spectrometry, allows the rapid identification of the type of conjugate, whereas the exact conjugation site can in general be determined only by additional NMR experiments.

Improved functional cardiac MR imaging using the intravascular contrast agent CLARISCAN

PURPOSE

Using segmented k-space turbo gradient echo MR techniques (TGE) contrast between blood and myocardium is often reduced in long axis views due to reduced in plane spin-refreshment, particularly in patients with low ejection fraction. The application of an intravascular contrast agent (CA) may improve endocardial border delineation.

MATERIALS AND METHODS

In 15 patients cardiac cine loops in two long axis and two short axis views were acquired during breath hold using a TGE sequence without and with increasing doses of CA (0.75, 2.0, 5.0 mg Fe/kg). Two independent observers evaluated left ventricular function (LVEF, modified Simpson's rule) and assigned a visual score (range: 0 = 'not visualized' to 6 = 'excellent visualization') for endocardial border delineation. Signal- and contrast-to-noise ratios (SNR; CNR) were determined.

RESULTS

Endocardial border delineation score for TGE was 1.7 +/- 0.6 and 3.9 +/- 0.6**, 4.4 +/- 0.5**, 4.6 +/- 0.4** for 0.75, 2.0, 5.0 mg Fe/kg of CA, respectively (**p < 0.01 vs. TGE). SNR of blood increased significantly with any dose of CA with a mild drop of myocardial SNR resulting in a significant increase of CNR blood/myocardium. The maximum effect with 2.0 mg Fe/kg was a >2-fold CNR increase. Inter- and intraobserver variability assessed according to the method of Bland-Altmann was reduced at 2.0 mg Fe/kg for determination of LVEF and reached statistical significance for LVEF <50%.

CONCLUSION

Intravascular CA increased CNR between blood and myocardium by a factor >2 and significantly improved the determination of cardiac volumes. The benefit in accuracy was most for patients with left ventricular ejection fraction <50%.

Phänotypische Charakterisierung einer DFNA6-Familie mit Tieftonschwerhörigkeit

BACKGROUND

Hereditary hearing impairment is a heterogeneous sensory defect with approximately two-thirds of all cases being nonsyndromic. Only two loci (DFNA1 and DFNA6/14/38) are associated with low frequency sensorineural nonsyndromic hearing impairment. DFNA6 was mapped to chromosome 4p16. Recessive mutations in the WFS1 gene are responsible for Wolfram syndrome; missense mutations inherited as an autosomal dominant result in low frequency sensorineural hearing impairment (LFSNHI).

PATIENTS AND METHODS

In this study we analyzed the phenotype of a large Hungarian family with LFSNHI and linkage to DFNA6. The family contains 14 affected persons.

RESULTS AND CONCLUSION

In general, these patients show a postlingual, sensorineural, bilateral, symmetric, nonsyndromic low frequency hearing impairment with a slow progression. This impairment is accompanied by normal vision and normal vestibular responses.

Interpretation of mass spectrometry data for high-throughput proteomics

Recent developments in proteomics have revealed a bottleneck in bioinformatics: high-quality interpretation of acquired MS data. The ability to generate thousands of MS spectra per day, and the demand for this, makes manual methods inadequate for analysis and underlines the need to transfer the advanced capabilities of an expert human user into sophisticated MS interpretation algorithms. The identification rate in current high-throughput proteomics studies is not only a matter of instrumentation. We present software for high-throughput PMF identification, which enables robust and confident protein identification at higher rates. This has been achieved by automated calibration, peak rejection, and use of a meta search approach which employs various PMF search engines. The automatic calibration consists of a dynamic, spectral information-dependent algorithm, which combines various known calibration methods and iteratively establishes an optimised calibration. The peak rejection algorithm filters signals that are unrelated to the analysed protein by use of automatically generated and dataset-dependent exclusion lists. In the "meta search" several known PMF search engines are triggered and their results are merged by use of a meta score. The significance of the meta score was assessed by simulation of PMF identification with 10,000 artificial spectra resembling a data situation close to the measured dataset. By means of this simulation the meta score is linked to expectation values as a statistical measure. The presented software is part of the proteome database ProteinScape which links the information derived from MS data to other relevant proteomics data. We demonstrate the performance of the presented system with MS data from 1891 PMF spectra. As a result of automatic calibration and peak rejection the identification rate increased from 6% to 44%.

Mass spectrometry-based clinical proteomics

In recent years, mass spectrometry (MS) has been recognized as a 'Gold Standard' tool for the identification and analysis of individual proteins in expression proteomics studies. Moreover, MS has proven useful for the analysis of nucleic acids for single nucleotide polymorphism (SNP) genotyping purposes. With the increased usage of MS as a standard tool for life science applications and the advancement of MS instrumentation, sample preparation and bioinformatics, MS technology has entered novel screening and discovery application areas that are beyond the traditional protein identification and characterization applications. The areas of clinical diagnostics and predictive medicine are just two prime examples of these fields. Predictive markers or biomarkers for early diagnosis of diseases are of growing importance for the human healthcare community. The goal of using MS in clinical proteomics is to generate protein profiles (mass to charge [m/z] ratio versus signal intensity) from readily available body fluids like serum, saliva and urine to detect changes in protein levels that reflect changes in the disease states. Whereas the results originating from individual protein markers may be intriguing, data resulting from the analysis of complex, multiple biomarker patterns may be unequivocal. These biomarker patterns are hidden in complex mass spectra and are not always obvious to the human eye. Sophisticated bioinformatics algorithms have to be applied to determine these unique biomarker patterns. Here, we review the latest developments concerning the use of MS for the discovery of biomarker patterns and for the identification of individual biomarkers in the field of clinical proteomics applications.

Regular physical activity improves endothelial function in patients with coronary artery disease by increasing phosphorylation of endothelial nitric oxide synthase

BACKGROUND

In stable coronary artery disease (CAD), exercise training has well-documented positive effects on arterial endothelial function. NO derived from endothelial NO synthase (eNOS) is regarded as a protective factor against atherosclerosis. The aim of the present study was to investigate the effects of exercise training on the endothelial function in relation to the expression of eNOS and Akt-dependent eNOS phosphorylation in the left internal mammary artery (LIMA) of patients with stable CAD.

METHODS AND RESULTS

In 17 training patients (T) and 18 control patients (C), endothelium-dependent vasodilation and average peak flow velocity (APV) in response to acetylcholine were measured invasively at study beginning and after 4 weeks in the LIMA. In LIMA tissue sampled during bypass surgery, eNOS expression and content of pospho-eNOS-Ser1177, Akt, and phospho-Akt were determined by Western blot and quantitative reverse transcriptase-polymerase chain reaction. After exercise training, LIMA APV in response to acetylcholine was increased by 56+/-8% (from +48+/-8% at beginning to +104+/-11% after 4 weeks, P<0.001). Patients in T had a 2-fold higher eNOS protein expression (T 1.0+/-0.7 versus C 0.5+/-0.3 arbitrary units, P<0.05) and 4-fold higher eNOS Ser1177-phosphorylation levels in LIMA-endothelium (1.2+/-0.9 versus 0.3+/-0.2 arbitrary units, P<0.01). A linear correlation was confirmed between Akt phosphorylation and phospho-eNOS levels (R=0.80, P<0.05) and between phospho-eNOS and Delta APV (R=0.59, P<0.05).

CONCLUSIONS

Exercise training in stable CAD leads to an improved agonist-mediated endothelium-dependent vasodilatory capacity. The change in acetylcholine-induced vasodilatation was closely related to a shear stress-induced/Akt-dependent phosphorylation of eNOS on Ser1177.

[Sudden cardiac death in a case of systemic sarcoidosis]

CLINICAL PRESENTATION

A 55-year-old woman required emergency medical care because of sudden weakness. On arrival of the emergency physician the patient presented with bradycardia with a normal rhythm. The blood pressure was not measurable. The patient complained of recurrent dizziness for a few months. Subsequently, the patient presented with an asystole and required reanimation and insertion of a temporary cardiac pacemaker. On admission at the hospital myocardial infarction was suspected.

CLINICAL AND LABORATORY TESTS

At the time of admission the patient presented in cardiogenic shock. The ECG revealed a 3rd atrioventricular block with idioventricular rhythm. Echocardiography showed reduced left ventricular function with global hypokinesia of the myocardium. Coronary artery disease was excluded by angiography. To exclude acute pulmonary embolism a CT-scan of the thorax was performed, revealing enlarged lymph nodes in the mediastinum.

TREATMENT AND RESPONSE TO THERAPY

Despite the administration of high-dose catecholamines and before a left atrial-to-femoral arterial assist device could be completely implanted the patient died of cardiogenic shock.

AUTOPSY

Autopsy revealed non-caseating epitheloid granulomas in the enlarged mediastinal lymph nodes as well as in the lung parenchyma, myocardium and several other organs.

CONCLUSION

The cardiac involvement of previously undiagnosed systemic sarcoidosis was the cause of sudden death. In case of ECG changes of unknown cause in persons without a history of structural cardiac disease sarcoidosis should be considered in the differential diagnosis.

MALDI-TOF mass spectrometry-based SNP genotyping

In recent years a growing demand for simple and robust SNP genotyping platforms has arisen from the widespread use of SNPs in industrial and public research. The resulting knowledge about genotype/phenotype correlations is of special interest for the identification of potential new drug targets and in the field of pharmacogenomics. However, full exploitation of the available genomic information requires vast numbers of SNP analyses, as large cohorts of patients have to be screened for a large number of markers. Only very few of the current SNP genotyping techniques can cope with the resulting demands concerning sample throughput, automation, accuracy and cost-effectiveness. MALDI-TOF mass spectrometry has the potential to develop into a 'Gold Standard' for high-throughput SNP genotyping - if it has not already done so. This review will focus on the latest developments of this technology.

Reversal of cardiogenic shock by percutaneous left atrial-to-femoral arterial bypass assistance

BACKGROUND

Recovery of myocardial function after revascularization of acutely occluded coronary arteries may require several days. During this critical time, patients in cardiogenic shock may have low output. A newly developed percutaneous left ventricular assist device (VAD) may offer effective treatment for these patients by providing active circulatory support.

METHODS AND RESULTS

Between May 2000 and May 2001, VADs were implanted in 18 consecutive patients who had cardiogenic shock after myocardial infarction. The device was connected to the patient's circulation by insertion of a 21F venous cannula into the left atrium by transseptal puncture; blood was returned to the iliac artery through an arterial cannula. Mean duration of cardiac assistance was 4+/-3 days. Mean flow of the VAD was 3.2+/-0.6 L/min. Before support, cardiac index was 1.7+/-0.3 L/min per m(2) and improved to 2.4+/-0.6 L/min per m(2) (P<0.001). Mean blood pressure increased from 63+/-8 mm Hg to 80+/-9 mm Hg (P<0.001). Pulmonary capillary wedge pressure, central venous pressure, and pulmonary artery pressure were reduced from 21+/-4, 13+/-4, and 31+/-8 mm Hg to 14+/-4, 9+/-3, and 23+/-6 mm Hg (all P<0.001), respectively. Overall 30-day mortality rate was 44%.

CONCLUSIONS

A newly developed VAD can be rapidly deployed in the catheterization laboratory setting. This device provides up to 4.0 L/min of assisted cardiac output, which may aid to revert cardiogenic shock. The left ventricle is unloaded by diverting blood from the left atrium to the systemic circulation, making recovery more likely after an ischemic event. The influence of this device on long-term prognosis warrants further investigation.

Functional cardiac MR imaging with steady-state free precession (SSFP) significantly improves endocardial border delineation without contrast agents

Contrast between blood and myocardium in standard turbo gradient echo MR techniques (TFE) used routinely in clinical practice is mainly caused by unsaturated inflowing blood. Steady-state free precession (SSFP) has excellent contrast even in the absence of inflow effects. In 45 subjects cardiac cine loops in two long axis projections were acquired using TFE and compared with SSFP. A visual score (range 0 worst - 3 best) was assigned for endocardial border delineation for six myocardial segments in two long axis views. Endocardial border delineation score for TFE was 1.3 +/- 0.3 per segment and 2.4 +/- 0.3 for SSFP (P < 0.0001). Signal intensity blood/signal intensity myocardium was 1.5 +/- 0.4 at enddiastole and 1.4 +/- 0.3 at systole for TFE and 3.5 +/- 1.1 and 3.2 +/- 1.3 for SSFP, respectively (P < 0.0001). SSFP increases contrast between blood and myocardium more than twofold, resulting in an improved endocardial border definition. This may reduce variability for the determination of cardiac volumes and ejection fraction.