Gerfried Gratze

Medical University of Graz, Gratz, Styria, Austria

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Publications (12)53.24 Total impact

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    ABSTRACT: In primary care the diagnosis of CHF and ECF accumulation is no triviality. We aimed to predict plasma BNP, CHF and ECF accumulation with segmental impedance spectroscopy while using and extending the electrodes of the conventional electrocardiography. Three combined multiple electrodes were added to the 15 lead ECG for segmental impedance spectroscopy and for measuring the maximal rate of segmental fluid volume change with heart action at the thorax and the legs. The obtained signals were analyzed by partial correlation analyses in comparison with plasma BNP, CHF classes, ejection fraction by echocardiography and cardiac index by double gas re-breathing. 119 subjects (34 healthy volunteers, 50 patients with CHF, NYHA classes II to IV and 35 patients without CHF) were investigated. The maximal rate of volume change with heart action at the thorax and at the legs, as well as the ECF/ICF ratio at the legs contribute equally and independently to the prediction of BNP and heart failure in an unknown test sample of 49 patients (multiple r=0.88, p<0.001). The ROC-curve for the predicted plasma BNP>400pg/ml gave an AUC=0.93. The absence or the presence of heart failure could be predicted correctly by a binomial logistic regression in 92.9 and 87.5% of cases, respectively. The methodology, which is based on inverse coupling of BNP release and of maximal blood acceleration and on sensitive detection of ECF overload, could enable the diagnosis of CHF with useful sensitivity and specificity while writing a routine-ECG.
    Medical Engineering & Physics 04/2014; · 1.78 Impact Factor
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    Gerfried Gratze, Harald Mayer, Falko Skrabal
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    ABSTRACT: To elucidate the mechanisms of orthostatic intolerance (OI) after endurance exercise which are incompletely understood. We investigated beat-to-beat haemodynamic and autonomic parameters in 51 male athletes during supine rest and after active standing the day before and 2 h after a marathon run. None of the subjects before the marathon [non-orthostatic intolerance (Non-OI)], but 14 after the marathon [orthostatic intolerance (OI)] exhibited with pre-syncope. There were no differences between OI and Non-OI before the marathon. After the marathon, only Non-OI was able to increase sympathetic modulation to resistance vessels from already increased basal levels in response to standing; OI could not. OI instead exhibited a decrease in total peripheral resistance and a paradoxical increase in parasympathetic sinus node modulation. We observed a significant correlation between serum potassium before the race and the maximally achieved sympathetic drive after the marathon (r = 0.55, P = 0.001). Post-exercise OI is associated with a 'high basal sympathetic modulation of vasomotor tone in combination with a diminished orthostatic sympathetic response' to resistance vessels. This situation may mimic the OI in some clinical conditions, which are also known to be associated with increased 'basal' sympathetic tone. The role of serum potassium deserves further study.
    European Heart Journal 07/2008; 29(12):1531-41. · 14.72 Impact Factor
  • G Gratze, H Mayer, F C Luft, F Skrabal
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    ABSTRACT: To test the hypothesis that enhanced postexercise vasodilatation is related to sympathetic drive to resistance vessels and to fast marathon performance. Prospective field study before and after running a marathon. 51 healthy amateur runners who volunteered to participate. The fastest competitor finished fourth, the slowest 1290 th out of 1324 participants. None. Competition time, beat-to-beat blood pressure by the vascular unloading technique, oscillometric blood pressure, beat-to-beat stroke volume by impedance cardiography, total peripheral resistance changes calculated from blood pressure and stroke volume changes, sympathetic modulation of vasomotor tone and parasympathetic modulation of sinus node function by spectral analysis of blood pressure and heart rate variability, baroreceptor reflex sensitivity by the sequence method. Slow performers, in contrast to fast performers, exhibited a higher 0.1 Hz band of diastolic blood pressure variability before the competition (0.1 Hz BPV) (40.0 (SD 2.39) vs 54.9 (2.47), p<0.001), diminished vasodilatation (-11.3 (4.78) vs -29.4 (3.23), p<0.01) and a decrease in stroke index (-14.9 (3.55) vs +0.9 (3.37), p<0.001) in response to the race. Single and multiple regression analyses further corroborated the findings. Fast performance in the marathon is associated with low sympathetic modulation of vasomotor tone, maintained stroke index postcompetition and enhanced exercise-induced vasodilatation. We postulate that maintaining a low level of sympathetic modulation to resistance vessels during the course of training may indicate its appropriateness, thus enabling fast performance by optimal postexercise vasodilatation and by prevention of postcompetition cardiac dysfunction. This will have to be tested in future longitudinal studies.
    British journal of sports medicine 02/2008; 42(11):882-8. · 3.67 Impact Factor
  • European Journal of Heart Failure 08/2006; 8(5):551-552. · 5.25 Impact Factor
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    ABSTRACT: We hypothesized that the extreme endurance exercise of an Ironman competition would lead to long-standing hemodynamic and autonomic changes. We investigated also the possibility of predicting competition performance from baseline hemodynamic and autonomic parameters. We have investigated 27 male athletes before competition, 1 h after, and then for the following week after the competition. The Task Force monitor was used to measure beat-to-beat hemodynamic and autonomic parameters during supine rest and active standing. Heart rate (P < 0.001) was increased, and stroke index (P = 0.011), systolic blood pressure (P = 0.004), diastolic blood pressure (P < 0.001), total peripheral resistance index (P < 0.001), and baroreceptor reflex sensitivity (P < 0.001) were decreased after the competition. The 0.05- to 0.17-Hz band of heart rate and blood pressure variability was increased (P < 0.001 and P < 0.001, respectively), the 0.17- to 0.40-Hz band of heart rate interval variability was decreased after the competition (P < 0.001). All parameters returned to baseline values 3 days after the competition. After the competition, the autonomic response to orthostasis was significantly impaired. The 0.05- to 0.17-Hz band of diastolic blood pressure variability before competition and weekly net exercise training, but not the other hemodynamic and autonomic parameters, were related to competition time in multivariate regression analysis (multiple r = 0.70, P < 0.001). The marked hemodynamic and autonomic changes after an ultraendurance race, which are compatible with myocardial depression in the face of sympathetic activation and reduction of afterload, return to baseline after only 1-3 days. Because the 0.05- to 0.17-Hz band of diastolic blood pressure variability contributes to the prediction of competition time, the analysis of blood pressure variability in the frequency domain deserves further study for the prediction of endurance capacity.
    Journal of Applied Physiology 12/2005; 99(5):1728-35. · 3.48 Impact Factor
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    ABSTRACT: Methods for stroke volume (SV) and ejection fraction (EF) measurements require the presence of qualified physicians and are not suited for continuous monitoring. To develop an automated non-invasive method for the measurement and continuous monitoring of SV and EF. We have designed a method for the measurement of EF and SV using multiple-site-impedance (z0) measurements, applying multiple frequencies of 5, 40 and 200 kHz whereby various segments of the human body, including volume changes within these segments, could be defined electrically. The obtained variables were used to train neuronal nets and related by multiple regression analyses to cardiac output (CO) as measured by a partial rebreathing Fick method (CO(r-fick)) or EF as measured by echocardiography (EF(echo)), respectively. A total of 129 subjects (48 with normal heart function and 81 with CHF, NYHA I-IV) were investigated. The multiply derived values of z0 and of change of impedance (dz/dt) were shown, by multiple regression analysis, to be significantly related to CO(r-fick) and to EF(echo), (total r=0.77, n=35, p<0.001, and r=0.81, n=47, p<0.001, respectively.). By training a neuronal net with the electrical data of 67 (out of 94) subjects, EF(echo) could be predicted in the remaining 27 subjects which were unknown to the neuronal net with a combined r=0.71 (p<0.001,n=27). In contrast, conventional impedance cardiography (ICG) was unable to predict either CO(r-fick) or EF(echo). The new method, which we call multi-site-frequency electromechanocardiography (msf-ELMC) appears promising for the automated electrical measurement of the mechanical heart action in patients with normal and reduced cardiac function.
    European Journal of Heart Failure 11/2005; 7(6):974-83. · 5.25 Impact Factor
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    ABSTRACT: Recent evidence suggests that the prodownregulatory Gly16 allele of the beta-2 adrenergic receptor (beta-2 AR) is associated with essential hypertension in African Caribbeans. To further investigate the effect of the glycine (Gly)16 and arginine (Arg)16 beta-2 AR variants on hemodynamics, we investigated the agonist-mediated in vivo vasodilation in normotensive Austrian Caucasians and analyzed the results with respect to the Gly16/Arg16 polymorphism. Fifty-seven normotensive men, 20 to 32 years of age with body mass index of 18.7 to 29.9 kg/m2, were genotyped for the Arg16/Gly16 beta-2 AR alleles. All 15 Gly16/Gly16 subjects, all 12 Arg16/Arg/16 subjects, and 27 of 30 heterozygous subjects underwent hemodynamic measurements while supine after an overnight fast. The observers were unaware of the subjects' genotypes. The subjects received a graded infusion of the selective beta-2 AR agonist salbutamol (0.07, 0.14, and 0.21 microgram/kg per minute, respectively), each dose over 8 minutes. Stroke volume and blood pressure were determined continuously by means of impedance cardiography and oscillometry, respectively. The last 4 minutes of each infusion were evaluated statistically. Basal mean blood pressure was higher in the Gly16/Gly16 subjects compared with Arg16/Arg16 subjects (mean+/-SD: 81.6+/-6.14 versus 75.2+/-4.93 mm Hg, P<0.01). Homozygous Gly16 subjects showed a significantly decreased vasodilation during the first dose of salbutamol infusion compared with Arg16/Arg16 subjects (Deltatotal peripheral resistance index -17.9+/-14.4 versus -30. 6+/-8.3%, P<0.01) despite increased sympathetic counterregulation in the Arg16/Arg16 group (Deltaheart rate +16.9+/-7.0% versus +8.6+/-7. 0%, P<0.01; Deltacardiac index +39.5+/-18.5% versus 21.4+/-18.8%, P<0.05). Our results provide additional evidence that the Gly16/Arg16 alleles of the beta-2 AR are intimately related to blood pressure regulation and deserve further studies in the pathogenesis of essential hypertension.
    Hypertension 06/1999; 33(6):1425-30. · 6.87 Impact Factor
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    ABSTRACT: The goal of the present study was to develop and evaluate algorithms for non-invasive, real-time, beat-to-beat monitoring of stroke index (SI), blood pressure (BP) and total peripheral resistance index (TPRI) which has a menu-driven interface, suitable for routine use by unskilled staff. In addition, it was our aim to include a meta-analysis for the evaluation of autonomic function derived from the above haemodynamic data. This includes spectral analysis of heart rate (HR), BP, SI and TPRI and the automatic calculation of baroreceptor reflex sensitivity. Impedance cardiography was used for beat-to-beat SI determination, Finapres corrected by an oscillometric blood pressure measurement (Dinamap) on the upper arm for beat-to-beat BP measurement. We demonstrate noise free recordings during physiological (head up tilt) and pharmacological intervention (alpha 1-, beta 2-adrenoreceptor agonists, insulin induced hypoglycemia). The newly developed software should prove valuable for physiological, pharmacological and clinical studies.
    Computers in Biology and Medicine 04/1998; 28(2):121-42. · 1.48 Impact Factor
  • Contraception 02/1998; 57(2). · 3.09 Impact Factor
  • Corrosion Science 01/1998; 40(6). · 3.62 Impact Factor
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    ABSTRACT: Without Abstract
    Osteoporosis International 01/1996; 6:297-297. · 4.04 Impact Factor
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Publication Stats

192 Citations
53.24 Total Impact Points

Institutions

  • 2005–2014
    • Medical University of Graz
      Gratz, Styria, Austria
    • Krankenhaus Barmherzige Brüder Wien
      Wien, Vienna, Austria
  • 1998–1999
    • Karl-Franzens-Universität Graz
      Gratz, Styria, Austria
  • 1996
    • Krankenhaus der Barmherzigen Brüder Graz
      Gratz, Styria, Austria