Biomedical subjects

H Hillenbrand

Publications and source records attributed to H Hillenbrand.

At least 19 recordsLinked to original sources

PubMed1994

[Analysis of the pressure-surface relation of the left ventricle with automatic echocardiographic contour detection].

UNLABELLED: Echocardiographic automatic border detection is a new on-line technique determinating the interface between blood and myocardial tissue thus having the potential to calculate cyclic changes in left ventricular cavity area in real time. It was the main purpose of the current study to evaluate left ventricular pressure-area relationship after administration of nitrates. In 12 patients with normal left ventricular function pressure-area relation was studied after a Swan-Ganz thermodilution catheter was placed in the wedge position and a high fidelity pig tail catheter was placed in the left ventricle. Left ventricular pressure and cyclic changes of cavity area were simultaneously analysed and displayed together as waveforms on the echo screen using a computer interfaced with the echo machine. All measurements were done before and five minutes after administration of 0.8 mg nitroglycerin. Mean systolic and diastolic blood pressure decreased significantly from 145/12 mmHg to 127/8 mmHg (p < 0.05). Mean systolic area decreased slightly from 10 cm2 to 9 cm2 (n.s.) whereas mean enddiastolic area decreased significantly from 18 cm2 to 15 cm2 (p < 0.05). Accordingly there was a downward and leftward shift of the diastolic pressure-area relationship following administration of nitroglycerin. CONCLUSION: Echocardiographic automated border recognition seems to be a promising new on-line method in the detection of left ventricular cavity area changes underlining its potential usefulness in the evaluation of left ventricular performance.

Adult↗

PubMed1992

Direct measurement of spin-lattice relaxation times of phosphorus metabolites in human myocardium.

T1 values of phosphorus metabolites visible in human cardiac 31P-MR spectra were determined in 12 volunteers at 1.5 T. Consecutive spectra were acquired with varying pulse repetition time (TR) from 1.6 to 24 s; volume selection was achieved with ISIS. T1's of creatine phosphate (CP), [gamma-P], [alpha-P], and [beta-P]ATP, 2-3 diphosphoglycerate, and phosphodiesters were 6.1 +/- 0.5, 5.4 +/- 0.5, 5.5 +/- 0.5, 5.8 +/- 1.0, 7.6 +/- 1.0, and 5.0 +/- 1.0 s, respectively. CP/ATP ratios showed little change with varying TR; linear regression of CP/ATP vs TR was of borderline significance (r = 0.28, P = 0.06). T1's for CP and ATP were also determined in standard solution (20 mM CP, 10 mM ATP) yielding T1CP of 8.7 +/- 0.2 and T1[gamma-P]-ATP of 9.9 +/- 0.7 s. Thus, T1's for CP and ATP were similar at 1.5 T in both human heart and standard solution. In human cardiac 31P-MR spectra, CP/ATP ratios may need little correction for partial saturation.

2,3-Diphosphoglycerate↗

PubMed1992

[The direct measurement of the spin-grid-relaxation times of phosphorus metabolites in the human myocardium].

The T1 relaxation times of the phosphorus metabolites in human heart muscle measurable by 31P-MR spectra were determined in 12 individuals using a 1.5 Tesla system. Several spectra were recorded consecutively with a pulse repetition time of 1.6 s to 24 s. The T1 times of creatine phosphate (CP), of gamma-, alpha-, beta-adenosintriphosphate (ATP), 2,3-diphosphoglycerate (2,3-DPG) together with anorganic phosphate) and phosphodiester (PDE) showed mean measurements of 6.1 +/- 0.5, 5.4 +/- 0.5, 5.0 +/- 0.5, 5.8 +/- 1.0, 7.6 +/- 1.0, and 5.0 +/- 1.0 s (M +/- SE). The accuracy of the ISIS technique was tested with a special phantom. T1 times were also measured in standard solutions (20 mM CP, 10 mM ATP); CP was 8.7 +/- 0.2 s and gamma-ATP was 9.9 +/- 0.7 s. Corrections for partially saturated 31P-MR spectra--at least for CP/ATP ratios--are relatively small.

2,3-Diphosphoglycerate↗

PubMed1992

31P magnetic resonance spectroscopy in dilated cardiomyopathy and coronary artery disease. Altered cardiac high-energy phosphate metabolism in heart failure.

BACKGROUND: The purpose of this work was to further define the value of cardiac 31P magnetic resonance (MR) spectroscopy for patients with coronary artery disease and dilated cardiomyopathy. METHODS AND RESULTS: Blood-corrected and T1-corrected 31P MR spectra of anteroseptal myocardium were obtained at rest using image-selected in vivo spectroscopy localization, a selected volume of 85 +/- 12 cm3, and a field strength of 1.5 T. Nineteen volunteers had a creatine phosphate (CP)/ATP ratio of 1.95 +/- 0.45 (mean +/- SD) and a PDE/ATP ratio of 1.06 +/- 0.53; in four patients with left anterior descending coronary artery (LAD) stenosis, six patients with chronic anterior wall infarction, and four patients with chronic posterior wall infarction, CP/ATP and phosphodiester (PDE)/ATP ratios did not differ from those in volunteers. Twenty-five measurements of 19 patients with dilated cardiomyopathy yielded a CP/ATP of 1.78 +/- 0.51 and a PDE/ATP of 0.98 +/- 0.56 (p = NS versus volunteers). When these patients were grouped according to the severity of heart failure, however, CP/ATP was 1.94 +/- 0.43 in mild (p = NS versus volunteers) and 1.44 +/- 0.52 in severe DCM (p < 0.05), respectively. No correlation was found between CP/ATP and left ventricular ejection fraction or fractional shortening, but correlation of CP/ATP with the New York Heart Association (NYHA) class was significant (r = 0.60, p < 0.005). Six patients with dilated cardiomyopathy were studied repeatedly before and after 12 +/- 6 weeks of drug treatment leading to clinical recompensation with improvement of the NYHA status by 0.8 +/- 0.3 classes. Concomitantly, CP/ATP increased from 1.51 +/- 0.32 to 2.15 +/- 0.27 (p < 0.01), whereas PDE/ATP did not change significantly. CONCLUSIONS: Cardiac high-energy phosphate metabolism at rest is normal in LAD stenosis and chronic myocardial infarction in the absence of heart failure. The CP/ATP ratio has low specificity for the diagnosis of dilated cardiomyopathy. However, CP/ATP correlated with the clinical severity of heart failure and may improve during clinical recompensation.

Adult↗

PubMed1991

[In vivo 31P-cardiac magnetic resonance spectroscopy: methods and the first clinical results].

31P-magnetic resonance (MR) spectra of the heart can be obtained from well-defined myocardial regions by combined MR imaging and variable selected volumes for spectroscopy. 31P-spectra of 33 volunteers and of 43 patients with dilated and hypertrophic cardiomyopathy and with coronary artery disease were quantified using a curve-fitting routine. To optimize our technique, we recorded unsaturated and partially saturated spectra in several volunteers. Relative peak areas and signal-to-noise ratios showed significant changes with varying pulse repetition times. Saturation factors were applied to correct spectra from volunteers and patients for the effects of partial saturation. Under resting conditions, peak areas of volunteers and patients from the various groups were statistically indistinct.

Adult↗

PubMed1991

[Experimental and clinical possibilities of MR spectroscopy of the heart].

MR-spectroscopy of the heart is a relatively new technique for the study of various aspects of cardiac metabolism. The majority of results has so far been obtained with the isolated perfused heart. Here, 31P-MR spectroscopy can be employed to measure high-energy phosphate metabolism and intracellular pH repeatedly and non-invasively. Using a technique called saturation transfer, velocities of enzymatic reactions, such as the creatine kinase reaction, can be measured. Intra- and extracellular Na+ and K+ concentrations can be registered with 23Na- and 39K-MR in conjunction with shift reagent. 13C-MR can be used to tackle carbohydrate metabolism. In-situ-R-spectroscopy allows determination of high-energy phosphates in intact large mammals. Clinical applications of MR-spectroscopy remain to be defined; preliminary results indicate high diagnostic and prognostic potential for patients with coronary artery disease and congestive heart failure.

Animals↗

PubMed1981

The necessity for trained advanced dental professionals.

The differentiation of the workforce in dentistry is discussed in terms of its history, the development of the specialties, and advanced education. The differentiations in the general practitioner workforce, through general practice residencies and the proposed advanced educational programs in general dentistry, are discussed. The possibility of further differentiation in the workforce by drastic changes in Section 18 of the Principles of Ethics of the American Dental Association (ADA) is analyzed and evaluated. The differentiations in the dental auxiliary workforce are noted and some conclusions and recommendations in all of these areas are presented.

Dental Auxiliaries↗

PubMed1980