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Biomedical subjects

M Borggrefe

Publications and source records attributed to M Borggrefe.

At least 19 recordsLinked to original sources
PubMed2006

A hybrid approach for quantification of aortic valve stenosis using cardiac magnetic resonance imaging and echocardiography: comparison to right heart catheterization and standard 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.

Aged↗
PubMed2006

Bridge to operation with the GPIIb/IIIa inhibitor abciximab in high-risk coronary patients.

BACKGROUND: Glycoprotein-IIb/IIIa inhibitors are now frequently used in the cardiological treatment of high-risk coronary patients even if the patient is considered suitable for surgical intervention. However, there is no consensus whether GPIIb/IIIa inhibitors should be stopped before operation because of an increased risk of bleeding or if surgery should even be delayed until the anticoagulating effect subsides. METHODS: From June 2002 to August 2003 140 patients who had to undergo primary aorto-coronary bypass for ongoing myocardial ischemia were enrolled in the present study. The patients received either clopidogrel, aspirin and heparin or additionally abciximab until operation. RESULTS: Although the intraoperative need for blood products was higher in the abciximab group, there was no significant difference in postoperative blood loss. The hemodynamic situation of the abciximab patients after the operation was better compared to the other groups. 30-day mortality was not increased when compared to the elective control group (6.7 % vs. 6.1 %). CONCLUSION: The GPIIb/IIIa inhibitor abciximab can be safely used as a bridge to operation and results in a better hemodynamic outcome in high-risk coronary patients while reducing the incidence of major ischemic events.

Abciximab↗
PubMed2005

Intravascular electric impedance spectroscopy of atherosclerotic lesions using a new impedance catheter system.

Newer techniques are required to identify atherosclerotic lesions that are prone to rupture. Electric impedance spectroscopy (EIS) can characterize biological tissues by measuring the electrical impedance over a frequency range. We tested a newly designed intravascular impedance catheter (IC) by measuring the impedance of different stages of atherosclerosis induced in an animal rabbit model. Six female New Zealand White rabbits were fed for 17 weeks with a 5% cholesterol-enriched diet to induce early forms of atherosclerotic plaques. All aortas were prepared from the aortic arch to the renal arteries and segments of 5-10 mm were marked by ink spots. A balloon catheter system with an integrated polyimide-based microelectrode structure was introduced into the aorta and the impedance was measured at each spot by using an impedance analyzer. The impedance was measured at frequencies of 1 kHz and 10 kHz and compared with the corresponding histomorphometric data of each aortic segment.Forty-four aortic segments without plaques and 48 segments with evolving atherosclerotic lesions could be exactly matched by the histomorphometric analysis. In normal aortic segments (P0) the change of the magnitude of impedance at 1 kHz and at 10 kHz (|Z|(1 kHz) - |Z|(10 kHz), = ICF) was 208.5 +/- 357.6 Omega. In the area of aortic segments with a plaque smaller than that of the aortic wall diameter (PI), the ICF was 137.7 +/- 192.8 Omega. (P 0 vs. P I; p = 0.52), whereas in aortic segments with plaque formations larger than the aortic wall (PII) the ICF was significantly lower -22.2 +/- 259.9 Omega. (P0 vs. PII; p = 0.002). Intravascular EIS could be successfully performed by using a newly designed microelectrode integrated onto a conventional coronary balloon catheter. In this experimental animal model atherosclerotic aortic lesions showed significantly higher ICF in comparison to the normal aortic tissue.

Animals↗
PubMed2005

Diagnostic value of stress echocardiography for the detection of restenosis after PTCA.

Stress echocardiography (SE) has become a widely accepted clinical tool for the non-invasive diagnosis of coronary artery disease (CAD). Previous studies have confirmed that SE has superior diagnostic value compared to exercise ECG testing. SE has also emerged as a cost-effective alternative to nuclear imaging techniques in patients where symptoms and/or conventional ECG stress testing have provided ambiguous results. Several studies have investigated the value of SE to detect significant restenosis after PTCA. However, in these studies, different methods have been used to induce cardiovascular stress such as physical exercise by bicycle or treadmill, pharmacologic stress testing (with dipyridamole or dobutamine) or transoesphageal atrial pacing. This review evaluates the published database of SE to detect restenosis in patients after successful PTCA. It includes 13 studies with a total of 989 patients performed at 3-6 months after the primary intervention. The diagnostic value, utility and limitations of SE is presented and discussed. The data show that SE has a high diagnostic value for detecting significant restenosis after PTCA. Mean sensitivity of SE was 74% (CI 69-79%), mean specificity was 87% (CI 84-89%). The positive predictive value (PPV) of SE was 83%, the overall negative predictive value (NPV) 97%. We conclude that, in the follow-up of patients after PTCA, SE has distinct advantages over other non-invasive methods and is a recommended method for the detection of those to be considered for repeat angiography.

Angioplasty, Balloon, Coronary↗
PubMed2005

Automated impedance cardiography for detecting ischemic left ventricular dysfunction during exercise testing.

UNLABELLED: Automated impedance cardiography (ICG) is an attractive method for noninvasive hemodynamic evaluation. The objective of our study was to evaluate the feasibility and diagnostic value automated ICG in patients with suspected coronary artery disease (CAD). We measured stroke index (SI) and cardiac index (CI) in 65 patients with suspected CAD at rest and during bicycle exercise testing. All patients underwent subsequent cardiac catheterization including coronary angiography (CA). Depending on the results of CA, patients were divided into three groups, patients without significant CAD (group 0), single vessel disease (group 1) or multivessel disease (group 2-3). In a subset of 20 patients, automated ICG was compared to measurements of CI by the thermodilution (TD) method. RESULTS: There were no significant differences in SI and CI at baseline between the three groups. At 75- and 100-watt exercise, patients in group 2-3 showed significantly lower mean values of SI and CI as compared to patients of group 0 and group 1 (all p < 0.05), indicating exercise-induced ischaemic left ventricular (LV) dysfunction. Three patients had to be excluded because of inappropriate quality of the ICG signals during exercise. Comparison of automated ICG with TD measurements of CI showed good correlations between both methods at rest (r = 0.73) and during exercise (r = 0.89-0.91). CONCLUSIONS: We conclude that hemodynamic monitoring by automated ICG is both feasible and practical during exercise testing. Automated ICG can provide reliable and valuable additional diagnostic information on LV function during exercise which is helpful for selecting those patients for angiography who are likely to benefit from coronary interventions.

Adult↗
PubMed2005

[Avoiding emergency situations under anticoagulant therapy with vitamin K antagonists].

Despite 50 years of clinical experience with vitamin K antagonists such as phenprocoumon or warfarin, many clinicians are uncertain how to start treatment, deal with overdose or bleeding complications, and how to bridge anticoagulation when treatment with vitamin K antagonists is interrupted. Patients with overdose of vitamin K antagonists or bleeding complications are treated with vitamin K, prothrombin complex concentrates (PCC), or recombinant factor VIIa. Rapid reversal of anticoagulation is only achieved by using PCC or recombinant factor VIIa. Both should be combined with vitamin K for a sustained effect. For elective surgery, treatment with vitamin K antagonists is paused and vitamin K given either orally or intravenously. Unfractionated or low molecular weight heparin is given when INR levels are below therapeutic range. Patients with contraindications to heparin may be treated with alternative anticoagulants such as danaparoid, lepirudin or fondaparinux.

Anticoagulants↗
PubMed2005

Midwall myocardial fibrosis in Becker-Kiener muscular dystrophy.

We report on a 38- year-old man with Becker-Kiener muscular dystrophy (BMD) and dilated cardiomyopathy without clinical symptoms of congestive heart failure who was referred for risk evaluation of sudden cardiac death. The degree of cardiac involvement in BMD varies greatly from no or hardly any cardiac abnormality to severe arrhythmias, dilatative cardiomyopathy and heart failure to heart transplantation or sudden cardiac death. These cardiac abnormalities have been related to replacement of the cardiomyocytes by connecting tissue or fat. In the clinical setting, cardiovascular magnetic resonance (CMR) has been proved to be a valid non-invasive method for obtaining anatomical and structural information of the heart. Furthermore, gadolinium-enhanced CMR can also characterize areas of myocardial fibrosis. Demonstration of extensive areas of fibrosis in an early stage of the disease might be a surrogate marker for an impaired clinical outcome. Therefore, serial CMR examinations starting upon diagnosis of the disease should be considered, as this may lead to an earlier recognition of cardiac involvement and may affect further management of the patient.

Adult↗
PubMed2005

[Primary electrical heart disease in adulthood--electrophysiological findings and therapy].

Sudden cardiac death accounts for 100,000 victims in Germany per year. Predominantly, patients with structural heart disease such as coronary artery disease or dilated cardiomyopathy are affected. However, approximately 5-10% of sudden deaths hit patients without structural disease of the heart. The proportion of young patients (< 40 years of age) in this group is even higher (10-20%). In younger patients significantly more diseases like hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia and primary electrical diseases of the heart could be observed such as long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia. The primary electrical diseases are different concerning their electrocardiographical pattern, clinical triggers of arrhythmias, results of invasive diagnostics and therapy. Meanwhile, molecular genetic screening can reveal specific mutations of ion channels and can identify consecutive functional defects. The significance of programmed ventricular stimulation is at present unclear concerning risk stratification in patients with Brugada syndrome and short QT syndrome and of no significance in long QT syndrome and catecholaminergic polymorphic ventricular tachycardias. The implantable cardioverter defibrillator is the therapy of choice in most symptomatic patients. With increasing knowledge as a result of sophisticated molecular genetic screening, identification of underlying ion channel defects and new details of the mechanisms of arrhythmogenesis, a potential genotype-guided therapy will gain more importance in the future.

Adult↗
PubMed2005

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.

Aged↗
PubMed2004

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.

Adult↗
PubMed2004

Paradoxical coronary embolism causing non-ST segment elevation myocardial infarction in a case of pulmonary embolism.

We describe the case of a 61-year-old woman who simultaneously suffered a pulmonary embolism and a myocardial infarction due to paradoxical coronary artery embolism. Transesophageal echocardiography with injection of agitated hydroxyethyl starch revealed a patent foramen ovale. Thrombophlebistis of the left saphenous vein with extension of thrombus into the femoral vein could be identified as the source of embolism. Paradoxical coronary embolism is an underrecognized cause of MI. Diagnosis is particularly difficult, when MI and PE coincide, because of the similarity in clinical signs and symptoms of both entities. A high level of clinical suspicion and echocardiography, especially if performed soon after presentation, can be the clue to early diagnosis of PDE.

Angioplasty, Balloon, Coronary↗
PubMed2004

Expression and activity of matrix metalloproteinase-2 in calcific aortic stenosis.

Calcific aortic stenosis is the main heart valve disease in the elderly, leading to massive focal calcification and thickening of the valve cusps. Matrix metalloproteinases (MMPs) are thought to contribute to this process. Therefore, the study assessed the expression of the gelatinases MMP-2 and MMP-9 and the endogenous tissue inhibitor of metalloproteinase (TIMP)-2 as well as the gelatinolytic activity in normal and stenotic valves. Human tricuspid aortic valves with and without calcific aortic stenosis were studied by immunohistochemistry for MMP-2, MMP-9 and TIMP-2. The gelatinolytic activity in native valve sections was assessed by gelatin in situ zymography with or without addition of the MMP activator p-aminophenymercuric acetate (APMA). Staining intensities for MMP-2 and TIMP-2 were elevated in stenotic valves as compared to controls. Minor staining of MMP-9 was present exclusively in stenotic valves. The morphologic distribution of gelatinolytic activity was comparable to the staining pattern of MMP-2, and since MMP-9 immunostaining demonstrated only a low number of positive cells, the observed gelatinolytic activity is likely due to MMP-2. Gelatinolytic activity was low in normal valves but significantly increased by the MMP activator APMA. In contrast, stenotic valves showed a strong basal gelatinolytic activity that could not be significantly enhanced by APMA suggesting that MMP-2 is present as a latent pro-enzyme in normal valves and activated in stenotic valves. Thus, MMP-2 might be involved in the matrix remodeling during calcific aortic stenosis.

Aortic Valve↗
PubMed2004

Incidence and electrophysiological characteristics of spontaneous ventricular tachyarrhythmias in high risk coronary patients and prophylactic implantation of a defibrillator.

OBJECTIVES: To assess the incidence and electrophysiological characteristics of spontaneous ventricular tachyarrhythmias after implantable cardioverter-defibrillator (ICD) implantation for primary prevention. DESIGN: Prospective observational study. PATIENTS: 41 consecutive patients, who fulfilled MADIT (multicenter automatic defibrillator implantation trial) I criteria, except for suppressibility by procainamide, and who received a prophylactic ICD. INTERVENTIONS: Subpectoral implantation of an ICD. MAIN OUTCOME MEASURES: Incidence of ventricular tachyarrhythmias and their electrophysiological characteristics with respect to timing of the arrhythmia, tachyarrhythmia cycle length, mode of termination, and clinical relevance. RESULTS: During a mean (SD) follow up of 30 (21) months 18 of 41 (43.9%) patients experienced 142 appropriate ICD treatments. The mean (SD) time to first event was 9.6 (15.1) months. One patient had ventricular fibrillation (VF), 12 patients ventricular tachycardia (VT), and five both VT and VF. The mean (SD) cycle length of monomorphic VT was 306 (42) ms. Of 142 episodes, 117 (82.3%) were terminated by antitachycardia pacing and another 25 (17.6%) by ICD discharges. Cumulative survival of hypothetical death, defined as treated VT with a cycle length < 260 ms or VF, was 83.2% after one year and 78.4% after two years. CONCLUSIONS: Patients with a left ventricular ejection fraction < 35%, a history of myocardial infarction, non-sustained VT, and inducible VT/VF are at high risk of VT/VF early after implantation. Therefore, implantation of a tiered treatment defibrillator seems to be justified.

Aged↗