How to: Success factors for the implementation and establishment of the "longitudinal curriculum" on communicative competencies at the Medical Faculty Mannheim

Communicative competencies are of great importance to the medical profession, hence the teaching of them has been continuously expanded in recent years at many German medical schools. While individual courses on communicative competencies have already been established in the curricula, there remains, in part, a lack of longitudinal anchoring over the entire course of medical study. In 2008 the Medical Faculty Mannheim began implementing a longitudinal curriculum for communicative competencies. This paper outlines the general and phase-specific success factors in this process and gives practical recommendations and tips based on the personal experiences of the authors and the existing literature.

Automated Noninvasive Central Blood Pressure Measurements by Oscillometric Radial Pulse Wave Analysis: Results of the MEASURE-cBP Validation Studies

BACKGROUND

Central blood pressure becomes increasingly accepted as an important diagnostic and therapeutic parameter. Accuracy of widespread applanation tonometry can be affected by calibration and operator training. To overcome this, we aimed to evaluate novel VascAssist 2 using automated oscillometric radial pulse wave analysis and a refined multi-compartment model of the arterial tree.

METHODS

Two hundred and twenty-five patients were prospectively enrolled. Invasive aortic root measurements served as reference in MEASURE-cBP 1 (n = 106) whereas applanation tonometry (SphygmoCor) was used in MEASURE-cBP 2 (n = 119).

RESULTS

In MEASURE-cBP 1, we found a mean overestimation for systolic values of 4 ± 12 mmHg (3 ± 10%) and 6 ± 10 mmHg (9 ± 14%) for diastolic values. Diabetes mellitus and low blood pressure were associated with larger variation. In MEASURE-cBP 2, mean overestimation of systolic values was 4 ± 4 mmHg (4 ± 4%) and 1 ± 4 mmHg (1 ± 7%) of diastolic values. Arrhythmia was significantly more frequent in invalid measurements (61 vs. 18%, P < 0.0001) which were most often due to a low quality index of SphygmoCor.

CONCLUSIONS

Central blood pressure estimates using VascAssist 2 can be considered at least as accurate as available techniques, even including diabetic patients. In direct comparison, automated measurement considerably facilitates application not requiring operator training and can be reliably applied even in patients with arrhythmias.

Authentic SP-based teaching in spite of COVID-19 - is that possible?

Objective: Medical conversation plays a central role in disease management and therapy. In teaching, standardized patients (SPs) are increasingly being used to present conversation situations with students and provide feedback afterwards. In order to maintain this teaching concept under pandemic conditions, a digital model was developed that should offer both high security and high authenticity. Methodology: A total of 176 teaching units of 45 minutes each were conducted digitally from May to August 2020. During the teaching units, medical students conducted interviews with SPs portraying various patients. The online conference software "HeiConf" was used for this purpose. During the teaching units, a total of 354 students were able to practice conversation techniques such as NURSE and SPIKES. After the teaching units, feedback was provided by students and SPs. Results: The digital lessons about medical conversation with SPs received positive feedback from SPs and students. The authenticity of the role portrayal of SPs seemed to be unaffected by the new format. Students were successful in training and observing conversation techniques. However, aspects of non-verbal communication, atmosphere and group dynamics as well as further discussions could not be carried out to the same extent as in the usual classroom teaching. Conclusion: The conversion of SP-based teaching to a digital format was successful in a short period of time and was able to prevent a cancellation of teaching units about medical conversation. Concrete conversation techniques could be tried out digitally by students. Due to the deficits of digital teaching in terms of non-verbal communication and atmosphere, a blended-learning format is planned for the future. In the first instance, concrete conversation techniques will be learned online in order to focus more on profound aspects of communication and discussions in a later physical teaching unit with SPs, thus enabling a learning experience that is as authentic as possible.

Recombinant human activated protein C upregulates cyclooxygenase-2 expression in endothelial cells via binding to endothelial cell protein C receptor and activation of protease-activated receptor-1

Prostacyclin (PGI2) has beneficial cytoprotective properties, is a potent inhibitor of platelet aggregation and has been reported to improve microcirculatory blood flow during sepsis. The formation of PGI2 in response to proinflammatory cytokines is catalysed by the inducible cyclooxygenase (COX) isoform COX-2. Recombinant human activated protein C (rhAPC, drotrecogin alfa (activated)) was shown to have multiple biological activities in vitro and to promote resolution of organ dysfunction in septic patients. Whether rhAPC exerts its beneficial effects by modulating prostanoid generation is unknown up to now. It was therefore the aim of the study to examine the in vitro effect of rhAPC on COX-2-mRNA-expression and PGI2 release from human umbilical vein endothelial cells (HUVEC). We found that rhAPC, at supra-therapeutical concentrations (500ng/ml-20μg/ ml), upregulated the amount of COX-2-mRNA in HUVEC at t=3–9h and caused a time- and dose-dependent release of 6-keto PGF1α, the stable hydrolysis product of prostacyclin. RhAPC further increased the stimulating effect of tumor necrosis factor-α (TNF-α) and thrombin on COX-2-mRNA-levels. Transcript levels of cyclooxygenase-1 (COX-1) and prostagland-in I2 synthase, however, were unaffected by the stimulation with rhAPC or thrombin. The upregulatory effect on COX2-mRNA levels was specific for rhAPC since the zymogen protein C in equimolar concentrations had no effect on COX-2-mRNA-levels or 6keto PGF1α-release. Western Blot analysis revealed an increase of COX-2-protein content in HUVEC after treatment with rhAPC. As shown by experiments using monoclonal antibodies against the thrombin receptor PAR-1 (mAb=ATAP2) and against the endothelial protein C receptor (EPCR; mAb=RCR-252), the effect of rhAPC on COX-2-mRNA up-regulation was mediated by binding to the EPCR-receptor and signaling via PAR-1. These results demonstrate that induction of COX-2-expression is an important response of HUVEC to stimulation with rhAPC and may represent a new molecular mechanism, by which rhAPC promotes upregulation of prostanoid production in human endothelium.

Multiple coupled resonances in the human vascular tree: refining the Westerhof model of the arterial system

The human arterial vascular tree can be described by multicompartment models using electrical components. First introduced in the 1960s by Noordergraaf and Westerhof, these hardware-based approaches required several simplifications. We were able to remove the restrictions using modern software simulation tools and improve overall model quality considerably. Whereas the original Westerhof model consisted of 121 Windkessel elements, the refined model has 711 elements and gives realistic pulse waveforms of the aorta and brachial and radial arteries with realistic blood pressures. Moreover, novel insights concerning the formation of the physiological aortic-to-radial transfer function were gained. Its being potentially due to the coupling of many small resonant elements gives new impetus to the discussion of arterial pressure wave reflection. The individualized transfer function derived from our improved model incorporates distinct patient characteristics and can potentially be used for estimation of central blood pressure values. NEW & NOTEWORTHY We were able to find an individualized transfer function giving realistic pulse waveforms and blood pressures using a multicompartment model of the arterial system. Based on the hardware-built Westerhof approach, several simplifications initially introduced in the 1960s could be reversed using software simulation. Overall model quality was improved considerably, and multiple coupled resonances were identified as potential explanation for the formation of the aortic-to-radial transfer function, giving new impetus to the discussion of arterial pressure wave reflection.

A comparative evaluation of electrical velocimetry and inert gas rebreathing for the non-invasive assessment of cardiac output

BACKGROUND

When assessing the function of the cardiovascular system, cardiac output (CO) is a substantial parameter. For its determination, numerous non-invasive techniques have been proposed in the recent years including inert gas rebreathing (IGR) and impedance cardiography (ICG). The aim of our study was to evaluate whether a novel ICG algorithm (electrical velocimetry) and IGR can be used interchangeably in the clinical setting.

METHODS

A total of 120 consecutive stable patients were included resulting in two pairs of repeated non-invasive cardiac output measurements.

RESULTS

The mean CO was 5.0 ± 1.2 l/min (range 2.6-8.6 l/min) using IGR and 4.4 ± 1.1 l/min (1.7-7.4 l/min) using ICG, respectively. Bland-Altman analysis revealed an acceptable agreement with a mean bias of 0.6 ± 1.2 l/min. We found a high reproducibility with a mean bias of 0.2 ± 0.7 l/min for IGR and 0.0 ± 0.3 l/min for ICG (p < 0.001), respectively. There was a statistically significant difference for unphysiological circulatory conditions represented by values of 2.6-4.1 l/min and 5.6-8.6 l/min.

CONCLUSIONS

Both non-invasive techniques are associated with low operating costs and require only a few expendable items for the rapid determination of cardiac function. We found an acceptable agreement between IGR and ICG as well as a high reproducibility, which was statistically significant higher for ICG. For cardiac output states exceeding the physiological range, we found a statistically significant difference. Consequently, values of cardiac function determined by either method should not be used interchangeably in the clinical setting.

ESC Working Group on Valvular Heart Disease Position Paper: assessing the risk of interventions in patients with valvular heart disease

AIMS

Risk scores provide an important contribution to clinical decision-making, but their validity has been questioned in patients with valvular heart disease (VHD), since current scores have been mainly derived and validated in adults undergoing coronary bypass surgery. The Working Group on Valvular Heart Disease of the European Society of Cardiology reviewed the performance of currently available scores when applied to VHD, in order to guide clinical practice and future development of new scores.

METHODS AND RESULTS

The most widely used risk scores (EuroSCORE, STS, and Ambler score) were reviewed, analysing variables included and their predictive ability when applied to patients with VHD. These scores provide relatively good discrimination, i.e. a gross estimation of risk category, but cannot be used to estimate the exact operative mortality in an individual patient because of unsatisfactory calibration.

CONCLUSION

Current risk scores do not provide a reliable estimate of exact operative mortality in an individual patient with VHD. They should therefore be interpreted with caution and only used as part of an integrated approach, which incorporates other patient characteristics, the clinical context, and local outcome data. Future risk scores should include additional variables, such as cognitive and functional capacity and be prospectively validated in high-risk patients. Specific risk models should also be developed for newer interventions, such as transcatheter aortic valve implantation.

The impact of pulmonary disease on noninvasive measurement of cardiac output by the inert gas rebreathing method

Cardiac output (CO) is an important parameter for diagnosis and therapy of heart diseases, but it is still difficult to determine. Innocor, a novel noninvasive inert gas rebreathing (IGR) system, has shown promising results. However, the impact of pulmonary diseases on IGR remains unclear. The aim of the study therefore was to assess the accuracy and reliability of IGR in patients with distinct chronic lung disease. A total of 96 patients were enrolled, including 48 consecutive patients with variant lung diseases (group A) and 48 pair-matched pulmonary healthy patients (group B). CO was measured with cardiac magnetic resonance imaging (CMR) and IGR. Lung function testing was done by spirometry [FEV(1)/FVC (forced expiratory volume in one second/forced vital capacity), VC (vital capacity)] and determination of the diffusing capacity of the lung for carbon monoxide divided by alveolar volume (DLCO/VA). In group A we found a mean CO of 4.7 ± 1.3 L/min by IGR and 4.9 ± 1.2 L/min by CMR. Group B showed a mean CO of 4.8 ± 1.4 L/min by IGR and 5.0 ± 1.3 L/min by CMR. Bland-Altman analysis revealed good correspondence between CMR and IGR, with an average deviation of 0.1 ± 1.0 L/min in group A and 0.1 ± 1.0 L/min in group B (p = 0.99). Multiple regression analysis for the pulmonary parameters did not show a statistically significant impact on the mean bias of CO measurements (FEV(1)/FVC: r = 0.01, p = 0.91; VC: r = -0.2, p = 0.13; and DLCO/VA: r = 0.04, p = 0.82). IGR allows a feasible determination of CO even in patients with lung diseases. The accuracy of the IGR method is not influenced by either pulmonary obstructive and restrictive diseases or a reduced DLCO.

A novel noninvasive ultrasonic cardiac output monitor: comparison with cardiac magnetic resonance

BACKGROUND

USCOM, a novel continuous wave Doppler (CWD) device, has been introduced for noninvasive determination of cardiac output (CO). The present study aimed to compare the accuracy and reproducibility of the new device, using cardiovascular magnetic resonance imaging (CMR) as the noninvasive gold standard.

METHODS AND RESULTS

The CO of 56 consecutive patients was prospectively determined by CWD either before or after CMR imaging. The CWD probe was placed in the suprasternal or supraclavicular notch aiming at the aortic valve. Valid CWD signals could be obtained in 45 patients yielding a CO of 5.3+/-1.1 L/min (range, 3.0-7.5 L/min) by CMR and 4.7+/-1.1 L/min by CWD (2.5-8.0 L/min, P = .004), respectively. CWD measurements showed an acceptable agreement with CMR (bias: 0.6+/-1.1 L/min) and a high reproducibility (bias: 0.1+/-0.4 L/min). Higher CO and body mass index (BMI) were identified as sources of inaccuracy in univariate analysis. By multivariate analysis, only CO(CMR) was found to be independently associated with larger variation. Estimated diameters of the left ventricular outflow tract (LVOT), a prerequisite for CO measurement by CWD, correlated only weakly with those measured by CMR.

CONCLUSIONS

Continuous wave Doppler is a feasible technique for measuring cardiac function. Although the overall agreement with CMR was acceptable, CWD showed a trend to underestimate CO. The estimated LVOT diameter by CWD is likely to be an important source of error. Nevertheless, the CWD device could be of clinical use especially for detection of intraindividual hemodynamic changes since a high reproducibility could be demonstrated.

Non-invasive measurement of cardiac output during atrial fibrillation: comparison between cardiac magnetic resonance imaging and inert gas rebreathing

OBJECTIVES

Atrial fibrillation (AF) is one of the most frequent heart rhythm disorders. It potentially influences cardiac function and its measurement. Cardiac magnetic resonance imaging (CMR) has become the new gold standard for non-invasive assessment of cardiac output (CO). A novel inert gas rebreathing (IGR) device based on the Fick Principle also proved promising in patients in sinus rhythm (SR). The aim of our study was to compare the agreement of non-invasive CO measurements between CMR and IGR in AF patients.

METHODS

A total of 68 patients, 34 with AF and 34 pair-matched controls in SR, were included.

RESULTS

Bland-Altman analysis showed good agreement between both methods, with an average deviation of 0.2 +/-1.2 l/min in the AF group versus 0.3 +/-1.0 l/min in the SR group (p = 0.77). IGR demonstrated good agreement for CO between 2.0 and 5.4 l/min. However, in hyperdynamic circulatory conditions (CO >5.5 l/min), the increasing disagreement of IGR and CMR measurements reached statistical significance.

CONCLUSIONS

Non-invasive CO measurements using CMR and IGR are feasible in patients suffering from AF. Good agreement was found between the two methods in an unselected cohort. Hyperdynamic circulatory conditions can lead to significant measurement differences which, however, do not affect the reproducibility of IGR.

Inert gas rebreathing: the effect of haemoglobin based pulmonary shunt flow correction on the accuracy of cardiac output measurements in clinical practice

BACKGROUND

Cardiac output (CO) is an important cardiac parameter, however its determination is difficult in clinical routine. Non-invasive inert gas rebreathing (IGR) measurements yielded promising results in recent studies. It directly measures pulmonary blood flow (PBF) which equals CO in absence of significant pulmonary shunt flow (Q(S)). A reliable shunt correction requiring the haemoglobin concentration (c(Hb)) as only value to be entered manually has been implemented. Therefore, the aim of the study was to evaluate the effect of various approaches to Q(S) correction on the accuracy of IGR.

METHODS

Cardiac output determined by cardiac magnetic resonance imaging (CMR) served as reference values. The data was analysed in four groups: PBF without correcting for Q(S) (group A), shunt correction using the patients' individual c(Hb) values (group B), a fixed standard c(Hb) of 14.0 g dl(-1) (group C) and a gender-adapted standard c(Hb) for male (15.0 g dl(-1)) and female (13.5 g dl(-1)) probands each (group D).

RESULTS

147 patients were analysed. Mean CO(CMR) was 5.2 +/- 1.4 l min(-1), mean CO(IGR) was 4.8 +/- 1.3 l min(-1) in group A, 5.1 +/- 1.3 in group B, 5.1 +/- 1.3 l min(-1) in group C and 5.1 +/- 1.4 l min(-1) in group D. The accuracy in group A (mean bias 0.5 +/- 1.1 l min(-1)) was significantly lower as compared to groups B, C and D (0.1 +/- 1.1 l min(-1); P<0.01).

CONCLUSION

IGR allows a reliable non-invasive determination of CO. Since PBF significantly increased the measurement bias, shunt correction should always be applied. A fixed c(Hb) of 14.0 g dl(-1) can be used for both genders if the exact c(Hb) value is not known. Nevertheless, the individual value should be used if any possible.

Association of NT-proBNP with severity of heart valve disease in a medical patient population presenting with acute dyspnea or peripheral edema

BACKGROUND AND AIM OF THE STUDY

The study aim was to perform a comprehensive evaluation of the association between N-terminal pro B-type natriuretic peptide (NT-proBNP) and the severity of heart valve diseases in a typical clinical population presenting with acute dyspnea or peripheral edema.

METHODS

Among 401 eligible patients, 210 demonstrated evaluable complete echocardiographic examinations. Plasma levels of NT-proBNP were measured after the initial clinical evaluation.

RESULTS

Patients with a prior valve replacement had higher plasma levels of NT-proBNP (median 3,366 pg/ml; n = 10) compared to all other patients (median 931 pg/ml; n = 200) (p < 0.05). In univariable analyses, NT-proBNP levels correlated with multiple valve diseases (r = 0.5; p < 0.001) and the severities of specific heart valve diseases, including aortic valve stenosis (AS) and regurgitation (AR), tricuspid (TR) and mitral valve regurgitation (MR) (p < 0.001). Within multivariable linear regression models, multiple heart valve diseases (Beta = 0.21; T = 3.56; p = 0.0001) and specifically valve regurgitations (AR (Beta = 0.16; T = 2.54; p = 0.012), MR (Beta = 0.36; T = 5.55; p = 0.0001), TR (Beta = 0.17; T = 2.55; p = 0.012)) were associated with increasing plasma levels of NT-proBNP. Patients with NT-proBNP plasma levels > 1,100 pg/ml showed the highest risk for future clinical events (odds ratio (OR) 4.86; p = 0.02), followed by patients with TR (OR 3.17; p = 0.03) and AS (OR 3.49; p = 0.06).

CONCLUSION

In addition to clinical assessment and echocardiographic evaluation, the measurement of plasma NT-proBNP levels may serve as a valuable additional indicator of the severity of heart valve disease in individual patients.

Percutaneous treatment of a coronary aneurysm by stent graft and drug-eluting stent implantation: a potential method to reduce stent graft restenosis

Coronary artery aneurysms (CAAs) can occur congenitally or secondary to specific disorders such as Kawasaki disease or atherosclerosis. Apart from a surgical approach, CAA can be treated by coronary stent graft (CSG) implantation. However, restenosis is frequent after CSG placement, precluding a wider use of this technique. We hypothesized that implantation of a drug-eluting stent (DES) within a CSG could be of use to avoid CSG restenosis. We report the case of a patient with a large aneurysm of the right coronary artery who underwent CSG implantation followed by DES placement. The immediate angiographic result showed complete exclusion of the aneurysm. Intravascular ultrasound confirmed good apposition of both the CSG and DES. Follow-up angiography after 23 weeks demonstrated a good long-term result without restenosis. The patient has remained asymptomatic during 12 months of follow-up. In conclusion, the present case suggests that CSG placement followed by DES implantation is a safe and effective approach to treat coronary aneurysms interventionally.

Incidence and clinical significance of left ventricular thrombus in tako-tsubo cardiomyopathy assessed with echocardiography

BACKGROUND

Left ventricular (LV) thrombus is a known complication of tako-tsubo cardiomyopathy (TC). However, current literature almost exclusively consists of isolated case reports. The aim of this study was to determine the incidence and clinical significance of LV thrombus formation in TC.

METHODS AND RESULTS

Over a 33-month period 52 patients with TC were assembled into a database at our institution. A retrospective database search was performed to identify patients with LV thrombus among these patients. LV thrombus, by echocardiography, was discovered in four patients[(8%); 95% confidence interval 3-19%]. Thrombus was present at the time of diagnosis in three patients. In one patient thrombus was absent initially and developed later. The LV apex was the site of thrombus formation in two patients, but the true apex was spared in the other two. All four patients had elevated serum levels of C-reactive protein (CRP). Two patients also had thrombocytosis. Treatment with low molecular weight heparin (LMWH) led to resolution of thrombus in all cases.

CONCLUSION

Our findings suggest that LV thrombus is a noteworthy complication in TC. It can occur both at initial presentation or at anytime later during the disease course. Elevated CRP levels and thrombocytosis may indicate a higher risk of thrombus formation.

Modification of the Harris-Benedict equation to predict the energy requirements of critically ill patients during mild therapeutic hypothermia

The aim of the present study was the comparison of calculated and measured values of the energy expenditure of critically ill patients during the different phases of therapeutic mild hypothermia.

PATIENTS AND METHODS

Five patients (mean age 40.6 years, range 23 to 68 years, 2 females) suffering from severe acute cerebral injuries who underwent mild hypothermia were prospectively included into the study. Indirect calorimetry measurements were made at intervals of 3-4 hours and subsequently, during the steady state, at least every 12 hours. The results were compared with the basal metabolic rate calculated by the Harris-Benedict equation.

RESULTS

A close linear correlation between body temperature and basal metabolism could be observed across a wide range of temperatures from 30.5 degrees C to 38.3 degrees C (r=0.82, p<0.001). One degree drop in temperature led to a 5.9% reduction in energy. During mild hypothermia, oxygen consumption was reduced by 71 mL/min (95% confidence interval 57 to 86 mL/min; p<0.001) as compared to base line. The basal metabolism rate was decreased by 30.3% (95% confidence interval 24.7 to 35.9%, p<0.001). The average value recorded was 16.7% below the values calculated in accordance with the Harris-Benedict equation (95% confidence interval 12.8 to 20.6%).

CONCLUSION

The immediate reduction in oxygen requirements achieved by hypothermia is linearly correlated with the reduction in temperature and the hypothermia induced reduction in oxygen requirement recorded by indirect calorimetry is considerably below that calculated in accordance with the Harris-Benedict equation. If indirect calorimetry should not be available and the Harris-Benedict equation is used, a corrective factor is therefore needed to avoid an inaccurate calorie administration.

Coronary artery disease in takotsubo cardiomyopathy

BACKGROUND

Significant coronary artery disease (CAD) is generally considered as an exclusion criterion for the diagnosis of takotsubo cardiomyopathy (TC). However, this may not be justified in all cases, because TC and CAD may coincide.

METHODS AND RESULTS

Among 821 consecutive patients who underwent urgent left heart catheterization for suspected acute coronary syndrome between December 2004 and August 2006 those with a final diagnosis of TC who also had a stenotic lesion (diameter stenosis on quantitative coronary angiography >50% and <75%) of the left anterior descending artery were evaluated. Four patients met the inclusion criteria. Previous coronary angiograms were available for 2 of these patients and showed no change in the angiographic appearance of the lesions. Intravascular ultrasound study was performed in the other 2 patients and demonstrated negative remodeling and no signs of plaque rupture, thrombus, positive remodeling or intimal dissection.

CONCLUSIONS

The present study supports the notion that TC and CAD are not mutually exclusive disease entities. Excluding the diagnosis of TC on the sole basis of an incidental finding of CAD may not be justified in all cases. Rather, a case-by-case decision process seems more appropriate.

Systemic and local levels of fetuin-A in calcific aortic valve stenosis

Calcific aortic valve stenosis, the most frequent heart valve disorder in developed countries, is an actively regulated process with similarities to bone formation. Fetuin-A has recently been identified as a potent circulating inhibitor of calcification. While several studies involving patients with end-stage renal disease have shown an association between low serum fetuin-A and cardiovascular calcification, nothing is known about fetuin-A serum levels in non-renal patients with calcific aortic valve stenosis. Furthermore, while fetuin-A has been localized in calcified areas of atherosclerotic arteries, data about fetuin-A deposition in stenotic aortic valves are unavailable at present. Serum fetuin-A levels were determined in patients with (n=31) and without (n=28) calcified aortic valve stenosis by ELISA. Creatinine and CRP levels were determined and glomerular filtration rate (GFR) was calculated by the MDRD formula. Immunohistochemistry for fetuin-A was performed on human calcified stenotic (n=14) and control (n=8) aortic valves using a monoclonal antibody. Serum fetuin-A levels were lower in patients with calcific aortic stenosis as compared to the control group (1.41+/-0.33 versus 1.57+/-0,27 mg/dl; p=0.046). This difference was particularly evident in individuals with a normal GFR >or=60 ml/min (1.36+/-0.24 versus 1.63+/-0.27 mg/dl; p=0.007). Furthermore, specific staining of fetuin-A was found in stenotic valves but not in healthy control valves. The data suggest a role of fetuin-A in the pathogenesis calcific aortic valve stenosis independently of the renal function and support the concept that mechanisms of calcium homeostasis are involved in the development of calcific aortic stenosis.

Impact of mitral E/A ratio on the accuracy of different echocardiographic indices to estimate left ventricular end-diastolic pressure

The objective was to determine the influence of left ventricular (LV) inflow pattern on the accuracy of different echocardiographic indices for estimation of LV end-diastolic pressure (LVEDP). Echocardiography with color tissue Doppler imaging (TDI) and LVEDP measurements using fluid-filled catheters were performed in 176 consecutive patients on the same day. Mitral peak diastolic velocities (E, A) and the difference in duration between pulmonary venous retrograde velocity and mitral A-velocity (PV(R)-A) were recorded by pulsed Doppler. Propagation velocity of the early mitral inflow (V(P)) was assessed using color M-mode. Early diastolic longitudinal (E'(lat)) and radial (E'(radial)) velocities of mitral annulus were measured by TDI. Area under ROC curve (AUC) for prediction of elevated LVEDP (> or =15 mm Hg) was computed for each parameter. For E/A > or =1 (98 patients, 46 with elevated LVEDP), the AUC values were: PV(R)-A: 0.914; E/E'(lat): 0.780; E/E'(radial): 0.729; E/V(P): 0.712 (p < 0.001). When E/A <1 (78 patients, 26 with elevated LVEDP), only PV(R)-A reached statistical significance (AUC = 0.893, p < 0.001). The conclusions were: PV(R)-A enabled the most accurate noninvasive estimation of LVEDP irrespective of LV filling profile and combined indices E/V(P), E/E'(lat) and E/E'(radial) represent more feasible alternatives for patients with mitral E/A-1.

Validation of the peak to mean pressure decrease ratio as a new method of assessing aortic stenosis using the Gorlin formula and the cardiovascular magnetic resonance-based hybrid method

BACKGROUND

We sought to validate the recently introduced peak to mean pressure decrease ratio (PMPDR), using the Gorlin formula and a hybrid method which combines cardiovascular magnetic resonance (CMR)-derived stroke volume with transaortic Doppler measurements to calculate aortic valve area (AVA).

METHODS

Data analysis in 32 patients with severe (AVA <or= 0.75 cm(2)) or moderate aortic stenosis who had prospectively been entered into our aortic stenosis database.

RESULTS

Gorlin-derived AVA was 0.61 +/- 0.10 cm(2) in severe and 0.92 +/- 0.14 cm(2) in moderate aortic stenosis (P < 0.01). Corresponding values for PMPRD were 1.61 +/- 0.10 and 1.73 +/- 0.18, respectively (P < 0.05). Sensitivity, specificity, positive and negative predictive values for PMPDR <1.5 to predict severe aortic stenosis were 0.12, 0.92, 0.67, and 0.44 as assessed by the Gorlin formula.

CONCLUSIONS

Using the Gorlin formula as the reference standard, our study confirms results of a previously reported study on the performance of PMPDR for assessment of aortic stenosis.

Prognostic value of platelet-derived growth factor in patients with severe sepsis

PRIMARY OBJECTIVE

Platelet-derived growth factor-BB (PDGF-BB) has been shown to promote the structural integrity of the vessel wall and to increase wound healing capacity. Aim of the present study was to determine the role of PDGF-BB in the context of outcome of septic patients. Furthermore, the effect of treatment with recombinant human activated protein C (rhAPC) on plasma levels of PDGF-BB in severe sepsis was evaluated as well as the in vitro effect of rhAPC on PDGF-BB-release from human endothelial cells (HUVEC). RESEARCH DESIGN, METHODS AND PROCEDURES: PDGF-BB levels were measured in 46 patients on day 3 of severe sepsis. Twenty-one of these patients received treatment with rhAPC. The in vitro effect of rhAPC on PDGF-BB-messenger RNA synthesis and release of PDGF-BB into supernatants was measured by reverse transcriptase-polymerase chain reaction and ELISA-methods.

MAIN OUTCOMES AND RESULTS

Survivors of severe sepsis presented with higher PDGF-BB levels than non-survivors (p < 0.05). Septic patients with PDGF-BB levels below 200 pg/ml were 7.3 times more likely (RR = 7.3, 95% CI: 1.4-44.5; p < 0.05) to die from sepsis than patients with higher PDGF-BB values. RhAPC (1-10 microg/ml) stimulated endothelial PDGF-BB-messenger RNA transcription and PDGF-BB-release in vitro. Plasma levels of PDGF-BB in patients receiving rhAPC were significantly (p < 0.01) higher (median 277.7; 25-75th percentiles: 150.5-414.4 pg/ml) than in patients not treated with rhAPC (median: 125.6; 25-75th percentiles: 55.3-344.7 pg/ml).

CONCLUSIONS

The ability of rhAPC to upregulate endothelial PDGF-BB production may represent a new molecular mechanism by which rhAPC controls vessel wall homeostasis and increases tissue healing capacity in severe sepsis. PDGF-BB may serve as useful laboratory marker to predict survival in patients presenting with severe sepsis.

Cardiovascular magnetic resonance findings in typical versus atypical forms of the acute apical ballooning syndrome (Takotsubo cardiomyopathy)

To assess cardiovascular magnetic resonance (CMR) findings in Takotsubo cardiomyopathy (TTC), 17 consecutive patients (15 women) with TTC who underwent left heart catheterization and gadolinium-enhanced CMR were evaluated. All patients had an abnormal electrocardiogram consisting of ST-segment elevation (n=8) and/or ST-segment depression (n=4) and/or T-wave inversion (n=14). One patient presented with left-bundle branch block. Left ventricular apical segments were involved in 10 patients (classical TTC), while they were not affected in 7 (variant form). Mean time delay between presentation and CMR was 9+/-7 days (range 3-24 days). CMR demonstrated complete resolution (n=4) or significant improvement of initial WMA in all cases. WMA were confined to basal and mid-ventricular segments (segments 1-12 in the 17-segment model) in the variant form, while they were virtually confined to the mid and apical left ventricle (segments 7-17) in classical TTC. Upon presentation ejection fraction by ventriculography was lower in classical TTC (36+/-7% vs. 58 +/-8%, p=0.0001). However, upon follow up ejection fraction by CMR was not different between classical and variant TTC (49+/-9% vs. 56+/-11%, p=0.23). Delayed hyperenhancement was absent in all but one patient. This finding may help differentiate TTC from entities with similar clinical presentations such as myocarditis and myocardial infarction, as the latter typically exhibits a subendocardial pattern of delayed hyperenhancement while the former usually displays a patchy subepicardial pattern.

[Pathogenesis of calcific aortic valve stenosis]

Calcific aortic valve stenosis is the most common heart valve disorder in the elderly and the most common cause of heart valve replacement in industrialized countries. For decades, it was considered a passive age-dependent degeneration of the valve tissue. Newer studies have shown, however, that the pathologic changes in calcific aortic valve stenosis are based on an actively regulated process of matrix remodeling and biomineralization. This review summarizes the currently available data and gives an outlook on potential therapeutic approaches.

Lower serum calcium levels are associated with greater calcium hydroxyapatite deposition in native aortic valves of male patients with severe calcific aortic stenosis

BACKGROUND AND AIM OF THE STUDY

The study aim was to evaluate the relationship between serum calcium levels and the degree of calcification found in stenotic aortic valves.

METHODS

Using atomic absorption spectroscopy, the hydroxyapatite content of 228 excised human stenotic aortic valves was determined and expressed as a percentage of valve mass. Left heart catheterization preceded valve replacement. In addition, serum levels of calcium and creatinine were determined before native calcific aortic valve excision.

RESULTS

Valves from male patients contained more hydroxyapatite than those of female patients (26 +/- 9 versus 22 +/- 9 mass%; p < 0.001). Patients presenting with lower serum calcium levels showed a slight trend towards higher levels of valve calcification (r = -0.15, p = 0.026), but this association appeared only within the subgroup of male patients. Male patients with lowest serum calcium levels displayed greatest valvular hydroxyapatite deposition (1st calcium tertiary: 29.5 +/- 8.9 mass% versus 2nd calcium tertiary 26.4 +/- 7.8 mass% versus 3rd calcium tertiary 21.4 +/- 8.9 mass%; n = 122; p = 0.001; r = -0.25; p = 0.006). This association was even more distinct in male patients with normal serum creatinine levels. Furthermore, serum calcium was inversely and significantly associated with serum C-reactive protein in male patients (r = - 0.34; p < 0.001).

CONCLUSION

Serum calcium levels appear to be inversely related to valve calcification in patients with severe calcific aortic stenosis (AS). This finding indicates the importance of systemic calcium metabolism in calcific AS, independent of manifest disorders of calcium metabolism or renal function. Interestingly, this association was evident only in male patients, suggesting a gender-dependent pathogenesis.

Recombinant human activated protein C upregulates the release of soluble fractalkine from human endothelial cells

Fractalkine is a unique endothelial cell-derived chemokine that functions both as a chemoattractant and as an adhesion molecule. Recent findings suggest that fractalkine plays an important role in inflammatory diseases by modulating leucocyte endothelial cell interactions. A modulating effect on the immune system in severe sepsis has been suggested for recombinant human activated protein C (rhAPC). However, a little is known about the effect of rhAPC on the endothelial release of soluble fractalkine. The effect of rhAPC (50 ng/ml to 10 microg/ml) and protein C (in equimolar concentrations) on the synthesis of fraktalkine-mRNA and release of soluble protein in human umbilical vein endothelial cells (HUVEC) was determined by reverse transcription-polymerase chain reaction and by an enzyme-linked immunosorbent assay. rhAPC at supra-pharmacological concentrations (1-10 microg/ml) stimulated fractalkine-messenger RNA-gene transcription and release of soluble fractalkine in a time- and dose-dependent manner, whereas the zymogen protein C was ineffective. As shown by experiments using monoclonal antibodies against the thrombin receptor, protease-activated receptor-1 (PAR-1), PAR-2 and against the endothelial protein C receptor (EPCR), the effect of rhAPC on fractalkine upregulation was mediated by binding to the EPCR-receptor and signalling via PAR-1. These in vitro data demonstrate that induction of fractalkine release is an important response of HUVEC to stimulation with rhAPC and may lead to a better understanding of the molecular pathways involved in the mode of action of rhAPC. Further clinical trials are needed to confirm the in vivo relevance of these data.

Coagulation activation is associated with interleukin-6 plasma levels in patients with mechanical prosthetic heart valves

BACKGROUND

The intensity of oral anticoagulant therapy in patients with mechanical heart valves is evaluated and controlled by the International Normalized Ratio (INR). However, intravascular coagulation activation can occur despite normal INR values and is related to clinical events. Here, anticoagulation efficiency was assessed by sensitive techniques and potential determinants of coagulation activation were identified.

PATIENTS AND METHODS

Forty patients were enrolled after they had undergone mechanical aortic valve replacement. As markers of coagulation activation, plasma concentrations of the D-dimer antigen were prospectively measured. The patients were classified into quartiles according to the D-dimer plasma antigen level. Serum concentrations of the inflammatory markers C-reactive protein (CRP) and Interleukin (IL)-6 were also assessed.

RESULTS

The D-dimer levels varied significantly despite therapeutic INR values. In patients with high D-dimer levels, the serum concentrations of IL-6 were significantly increased (top vs. bottom quartile, median, 1.35 versus 0.80 pg/ml; p<0.05), suggestive of subclinical inflammation. There was no association between the D-dimer levels and age, sex, cardiovascular risk factors or time since valve replacement.

CONCLUSION

Coagulation activation and inflammation are associated with mechanical heart valves. The D-dimer antigen and IL-6 may be more sensitive than INR and CRP to detect these states and, therefore, could prove valuable additional markers, e.g., in determining the efficacy of new anticoagulant drugs.

Prevalence of atherosclerosis of the coronary and extracranial cerebral arteries in patients undergoing aortic valve replacement for calcified stenosis

BACKGROUND AND AIM OF THE STUDY

The study aim was to investigate the coexistence of various atherosclerotic changes in patients with non-rheumatic calcific aortic valve stenosis (AS), since calcific AS shares various clinical risk factors with atherosclerosis.

METHODS

In 282 consecutive patients with severe calcific stenosis of a tricuspid aortic valve scheduled for aortic valve replacement, the prevalence of atherosclerotic changes of the coronary and extracranial cerebral arteries were assessed using coronary angiography and Doppler sonography, respectively.

RESULTS

The severities of coronary and extracranial cerebral artery atherosclerosis were significantly associated (p = 0.005). The prevalence and severity of both coronary and extracranial cerebral artery atherosclerosis were age-dependent. Coronary or extracranial cerebral artery stenosis was present in 59% and 16% of patients, respectively, while 91% of the study population and all patients aged > 80 years showed atherosclerosis of the coronary and/or extracranial cerebral arteries.

CONCLUSION

The data obtained indicated a very high prevalence of atherosclerotic changes in patients with calcific AS, suggesting pathogenetic similarities of both disorders. Routine screening of the extracranial cerebral arteries is warranted in all patients with calcific AS and scheduled for valve replacement.

A hybrid approach for quantification of aortic valve stenosis using cardiac magnetic resonance imaging and echocardiography:

We replaced Doppler-derived stroke volume in the continuity equation (method A) by either right heart catheterization-derived stroke volume (method B) or cardiovascular magnetic resonance-derived stroke volume (method C) to calculate aortic valve area in 20 consecutive patients with moderate or severe aortic stenosis. Comparison of both hybrid methods (methods B and C) by Bland-Altman analysis showed a mean difference near zero, a spread within two standard deviations and very similar limits of agreement. More importantly, all patients were classified into the same category of severity by both methods.

Utility of combined parameters of common carotid intima-media thickness or albuminuria in diagnosis of coronary artery disease in women

BACKGROUND

Noninvasive testing for suspected coronary artery disease is challenging. We prospectively investigated whether measurements of carotid intima-media thickness in the presence or absence of albuminuria in patients with stable chest pain syndromes can be used as a noninvasive test algorithm for prediction of significant coronary artery disease. Additionally, this algorithm was tested with regard to gender differences.

METHODS

Consecutive patients (79 men and 72 women) with stable chest pain syndromes and suspected coronary artery disease admitted for coronary angiography were studied. Measurements of intima-media thickness were performed by ultrasound. Urinary albumin excretion was measured in a random urine specimen. A positive test for coronary artery disease was defined as an intima-media thickness >or=1 mm or albuminuria.

RESULTS

Sensitivity, specificity and positive likelihood ratio for a combination of intima-media thickness values >or=1 mm or presence of albuminuria to predict coronary artery disease were, respectively, 0.5, 0.73 and 1.27 in men and 0.68, 0.79 and 3.32 in women. Sensitivity, specificity and positive likelihood ratio for exercise ECG were, respectively, 0.54, 0.48 and 1.08 in men and 0.47, 0.45 and 0.8 in women.

CONCLUSIONS

Intima-media thickness of the common carotid artery or presence of albuminuria are clinically valuable parameters in the noninvasive diagnostic work up of women with stable chest pain syndromes. Their value is limited in men.

Statin therapy of calcific aortic stenosis: hype or hope?

Calcific aortic stenosis, with a prevalence of 3-9%, is the most frequent heart valve disease and the main cause for valve replacement in patients over 60 years of age. Once thought to be caused by a passive calcium precipitate within the aortic valve leaflets, there is now increasing evidence that development and progression of calcific aortic valve disease may be triggered by underlying genetic and cardiovascular risk factors, and is regulated by an active cellular process involving inflammatory pathways. Targeted drug therapy to prevent the progression of calcific aortic valve disease should ideally be based on the knowledge of risk factors and the molecular pathogenesis of the disease. Conflicting data exists on the potency of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (i.e. statins) to influence both risk factors and inflammatory pathways by lowering lipid levels and exerting anti-inflammatory properties, respectively. In this review, various aspects of the molecular pathogenesis of calcific aortic stenosis will be summarized and connected with recent experimental and clinical studies that address the potential benefit of the targeted drug therapy by statins in order to prevent the progression of the disease.

Tumor necrosis factor alpha promotes an osteoblast-like phenotype in human aortic valve myofibroblasts: a potential regulatory mechanism of valvular calcification

Valvular calcification during calcific aortic stenosis is associated with morphological features of bone formation and expression of various bone-associated proteins, which are both associated with marked leukocyte infiltration of the calcified valve areas. The pro-inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) is abundantly present in areas of leukocyte infiltration in stenotic aortic valves. We therefore hypothesized that valvular calcification might be actively regulated by an inflammatory process involving TNF-alpha. Upon stimulation with TNF-alpha, human aortic valve myofibroblasts cultured under mineralizing conditions showed an increased formation of calcified, alkaline phosphatase (ALP)-enriched cell nodules, ALP activity, concentration of the bone-type ALP isoenzyme, and concentration of osteocalcin, all of which are markers of an osteoblast-like cellular phenotype. By electrophoretic mobility shift assay, DNA binding of the essential osteoblastic transcription factor Cbfa-1 was increased compared to untreated controls. These results support the concept that aortic valve calcification is associated with an osteoblast-like phenotype of local myofibroblasts. In addition, the data demonstrate direct mechanistic evidence that aortic valve calcification may be actively regulated by an inflammatory process involving TNF-alpha.

Prognostic value of plasma N-terminal pro-brain natriuretic peptide in patients with severe sepsis

BACKGROUND

Increased plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) have been identified as predictors of cardiac dysfunction and prognosis in congestive heart failure and ischemic heart disease. In severe sepsis patients, however, no information is available yet about the prognostic value of natriuretic peptides. Therefore, the aim of the present study was to determine the role of the N-terminal prohormone forms of ANP (NT-proANP) and BNP (NT-proBNP) in the context of outcome of septic patients. Furthermore, the effect of treatment with recombinant human activated protein C [drotrecogin alfa (activated)] on plasma levels of natriuretic peptides in severe sepsis was evaluated.

METHODS AND RESULTS

Fifty-seven patients with severe sepsis were included. Levels of NT-proANP and NT-proBNP were measured on the second day of sepsis by ELISA. Septic patients with NT-proBNP levels >1400 pmol/L were 3.9 times more likely (relative risk [RR], 3.9; 95% CI, 1.6 to 9.7) to die from sepsis than patients with lower NT-proBNP values (P<0.01). NT-proANP levels, however, were not predictive of survival in our patient population. A highly significant correlation was found between troponin I levels and plasma concentrations of NT-proBNP in septic patients (r=0.68, P<0.0001). In addition, troponin I significantly accounted for the variation in NT-proBNP levels (P<0.0001), suggesting an important role for NT-proBNP in the context of cardiac injury and dysfunction in septic patients. Twenty-three septic patients who received treatment with drotrecogin alfa (activated) presented with significantly lower concentrations of NT-proANP, NT-proBNP, and troponin I compared with patients not receiving drotrecogin alfa (activated).

CONCLUSIONS

NT-proBNP may serve as useful laboratory marker to predict survival in patients presenting with severe sepsis.

[Chlamydia pneumoniae--a new risk factor for calcific aortic stenosis?]

BACKGROUND

Nonrheumatic, calcific aortic stenosis is the main heart valve disease and the main cause of heart valve replacement in the elderly. Recent studies suggest that it is based on a chronic inflammatory process. The pathogenetic mechanisms, however, are unclear.

METHODS

A MEDLINE search was conducted for the phrases "chlamydia pneumoniae" and "aortic valve", and all articles published between 1966 and May 2004 were evaluated. Data presented as letter or congress abstract was also included.

RESULTS

Clinical and histopathologic studies demonstrate an association of calcific aortic stenosis and cardiovascular risk factors similar to atherosclerosis. As for atherosclerosis, infection with Chlamydia (C.) pneumoniae is also discussed as a further potential risk factor for calcific aortic stenosis. Previous seroepidemiologic and pathologic studies using various detection methods yielded heterogeneous results.

CONCLUSION

Thus, data suggesting a pathogenetic association of C. pneumoniae and calcific aortic stenosis should be interpreted cautiously.

A Hybrid Approach for Quantification of Aortic Valve Stenosis Using Cardiac Magnetic Resonance Imaging and Echocardiography

BACKGROUND

Doppler-derived calculation of aortic valve area (AVA) using the continuity equation can be difficult at times, e.g. due to poor acoustic windows, heavy calcification of the aortic valve, or significant flow acceleration in the left ventricular outflow tract. The aim of this study was to compare AVA as assessed by means of transthoracic echocardiography (TTE) with a hybrid approach, where the Doppler-derived numerator in the continuity equation was replaced by cardiovascular magnetic resonance (CMR) determination of stroke volume.

METHODS

Twenty consecutive patients admitted for evaluation of aortic stenosis underwent transthoracic echocardiography and CMR determination of stroke volume within a time period of 3 weeks. Additionally, continuous-wave Doppler spectra of the aortic valve were acquired immediately after the CMR examination.

RESULTS

There was no statistically significant difference for mean AVA between the two methods (0.88 +/- 0.23 cm2 by the standard continuity equation versus 0.86 +/- 0.23 cm2 by the hybrid approach, p = 0.55; r = 0.73, p < 0.01). The mean difference was 0.02 cm2 and the limits of agreement were -0.32 to 0.36. Only 2 patients were classified differently by the two methods. Intraobserver and interobserver variability and reproducibility were superior for the hybrid approach.

CONCLUSION

The hybrid method for determination of AVA is an excellent alternative to the standard approach by TTE.

Drotrecogin alfa (activated) inhibits NF-kappa B activation and MIP-1-alpha release from isolated mononuclear cells of patients with severe sepsis

OBJECTIVE AND DESIGN

Non-anticoagulant biological activities, such as anti-inflammatory and anti-apoptotic mechanisms of action, have been suggested for recombinant human activated protein C (rhAPC; drotrecogin alfa (activated)). However, these mechanisms are much less characterized and understood than rhAPC's anticoagulant activity. Aim of the study was to determine the effect of rhAPC on the activity of the pro-inflammatory transcription factor nuclear factor kappa B (NF-kappaB) in mononuclear cells isolated from septic patients and to characterize an effect downstream from NF-kappaB activation, such as the release of the NF-kappaB-controlled chemokine Macrophage Inflammatory Protein-1-alpha (MIP-1-alpha).

SUBJECTS

Peripheral blood was obtained from 13 septic patients and from 8 healthy controls.

METHODS

Mononuclear cells were isolated by Ficoll-Paque density gradient centrifugation and were incubated with or without rhAPC (10 microg/ml) for 2 h for the measurement of NF-kappaB activity in cell lysates or alternatively for 6 h for the determination of MIP-1-alpha levels in supernatants. NF-kappaB activity was measured by an ELISA-based assay directed against the p50 and the p65 subunit of NF-kappaB.

RESULTS

RhAPC, at supra-pharmacological concentration (10 microg/ml), significantly inhibited NF-kappaB activity and the release of MIP-1-alpha ex vivo in isolated mononuclear cells from patients with severe sepsis. In mononuclear cells of healthy subjects, however, rhAPC did not change NF-kappaB activity. Basal NF-kappaB activity early in severe sepsis was not predictive for survival.

CONCLUSIONS

RhAPC at supra-pharmacological concentration (10 microg/ml) inhibits the activity of NF-kappaB in ex vivo isolated mononuclear cells of septic patients as well as the release of MIP-1-alpha, a proinflammatory chemokine regulated by NF-kappaB. These findings may represent immunomodulatory pathways by which rhAPC exerts specific anti-inflammatory activity in vitro in addition to its known anticoagulant and profibrinolytic activity and should be further investigated in an in vivo setting.

Comparison of Impedance Cardiography and Thermodilution-Derived Measurements of Stroke Volume and Cardiac Output at Rest and During Exercise Testing

BACKGROUND

Non-invasive evaluation of haemodynamic variables remains a preferable and attractive option in both pharmacologic research and clinical cardiology.

OBJECTIVES

The objective of this study was to evaluate the correlation, feasibility and diagnostic value of haemodynamic measurements by ICG with the thermodilution (TD) method at rest and during exercise testing.

METHODS

We measured stroke volume (SV) and cardiac output (CO) with both methods in 20 patients with suspected coronary artery disease (CAD). All measurements were performed simultaneously at rest and during bicycle exercise.

RESULTS

There was a highly significant correlation (p < 0.001) for measurements of SV between both methods at rest (r = 0.83) and during exercise (r = 0.85-0.87) with 50-100 watts. For measurements of CO, the respective correlations were r = 0.85 at rest and r = 0.92-0.94 during exercise. The mean difference for measurements of SV were 3.8 +/- 12.6 ml at rest and 6.5+/- 11.4 ml during exercise. For measurements of CO, the mean difference between both methods was 0.9 +/- 1.0 l/min at rest and 1.0+/- 0.8 l/min during exercise. Compared to TD measurements, ICG had a bias to overestimate SV and CO of approximately by 5-10%. One patient had to be excluded because of inappropriate quality of the ICG signals during exercise.

CONCLUSIONS

ICG is a feasible and accurate method for non-invasive measurements of SV and CO. Haemodynamic measurements by ICG were correlated highly significant to simultaneous measurements by the TD method.

Inflammatory regulation of extracellular matrix remodeling in calcific aortic valve stenosis

BACKGROUND

Calcific aortic stenosis (AS), the most frequent heart valve disorder in developed countries, leads to the calcification and fibrous thickening of the valve. While several studies have addressed the process of valvular calcification, the molecular pathomechanisms of the extensive matrix remodeling remain unclear. Because inflammation is present in stenotic valves, we hypothesized that the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha) might influence cell proliferation and regulate the expression and activation of matrix metalloproteinases (MMPs)--enzymes that are thought to be involved in calcific AS.

METHODS

Immunohistochemistry for leukocytes, TNFalpha, MMP-1, and the endogenous MMP inhibitor tissue inhibitor of metalloproteinase (TIMP)-1 was performed on human stenotic (n = 19) and control (n = 8) valves. Primary cultures of human aortic valve myofibroblasts were incubated with and without TNFalpha, and cell proliferation was assessed. The expression and activation of MMP-1 were detected by Western blotting and a specific MMP-1 activity assay.

RESULTS

Control valves showed scattered macrophages and low expression of TNFalpha, MMP-1, and TIMP-1. In stenotic valves, leukocyte infiltration and a strong, colocalized expression of TNFalpha and MMP-1 were present, while TIMP-1 remained unchanged. Double-label immunofluorescence localized TNFalpha mainly to macrophages. In cultured human aortic valve myofibroblasts, TNFalpha stimulated proliferation and induced a time-dependent increase in MMP-1 expression and activation, while TIMP-1 remained unchanged.

CONCLUSION

The results indicate that matrix remodeling in calcific AS involves the expression and activation of MMPs. Activated leukocytes, by the secretion of TNFalpha, may stimulate valvular myofibroblasts to proliferate and express MMPs, thus regulating actively the matrix remodeling in calcific AS.

Influence of receptor activator of nuclear factor kappa B on human aortic valve myofibroblasts

Calcific aortic valve stenosis, the main heart valve disease in the elderly, is based on progressive calcification and fibrous thickening of the valve. Several reports addressed the pathogenesis of tissue calcification in this disorder, but few data exist on the molecular mechanisms of the fibrosis and remodeling of the extracellular matrix. The cytokine "receptor activator of nuclear factor kappa B ligand" (RANKL), is expressed in stenotic aortic valves and involved in valvular calcification during calcific aortic valve stenosis. The present study aimed to assess the influence of RANKL on the molecular mechanisms of connective tissue remodeling. In an established cell culture model of primary human aortic valve myofibroblasts, stimulation with RANKL increased cell proliferation as compared to medium alone. Matrix metalloproteinase (MMP)-1 was detectable time-dependently in conditioned media from RANKL-stimulated cells, but absent in media from control cells. MMP-1 activity was increased by RANKL, as measured by collagenase activity assay. Zymography showed an increase in active MMP-2 in RANKL-stimulated cells. These results support the concept that MMPs are involved in the connective tissue remodeling during calcific aortic valve stenosis. RANKL might regulate this process by promoting cell proliferation and MMP expression and activation.