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Biomedical subjects

H Mayr

Publications and source records attributed to H Mayr.

At least 19 recordsLinked to original sources
PubMed1992

Quantitative assessment of aortic regurgitation by magnetic resonance imaging.

Thirty patients with aortic regurgitation and 10 controls were examined using an 0.5 T superconducting magnet with ECG gating. In each case a multislice-multiphase spinecho study in sagittal-coronal double angulated projection (four-chamber equivalent) was performed to assess left and right ventricular volumes, ejection fraction and regurgitation fraction. Additionally, a blood-flow sensitive cine-study (gradient echo, FAME) was performed to visualize direction and area of regurgitant jet. Magnetic resonance imaging (MRI) data were compared with quantitative and qualitative assessment of aortic regurgitation by angiography, Doppler and colour flow mapping. Using the FAME mode MRI, we were able to detect the regurgitant jet as an area of signal loss within the left ventricle in all patients; moderate correlation to jet area was determined by colour flow mapping (R = 0.60, P less than 0.001). Determination of left and right ventricular end-diastolic, end-systolic and stroke volumes by MRI revealed excellent correlation with invasive data (R = 0.94, P = 0.0001). With MRI regurgitant fraction (RF) could be calculated from the difference between right and left ventricular stroke volumes, which showed good correlation with invasively determined RF (R = 0.91, P = 0.001) and with qualitative Sellers' scoring (R = 0.70, P less than 0.001), respectively. Thus MRI provides the basis for noninvasive detection and quantification of aortic regurgitation.

Adolescent↗
PubMed1992

Doppler sonographic evaluation of the CarboMedics bileaflet valve prosthesis: one-year experience.

Between April 1989 and March 1991, 237 CarboMedics bileaflet valve prosthesis carriers (165 aortic and 72 mitral valves, mean age 54.4 years) were studied prospectively with pulsed- and continuous-wave Doppler at a mean interval of 11.4 months following surgery in order to establish ranges of normal flow velocities and pressure gradients. Physical examination revealed no signs of prosthetic dysfunction or heart failure. Postoperative left ventricular function as measured by fractional shortening was 37% for aortic valve carriers and 30% for mitral valve carriers (p = NS). Mean peak velocity (+/- SD) across the aortic valve was 2.6 m/sec (+/- 0.4) and calculated instantaneous peak pressure gradient ranged from 11 to 58 mmHg (mean 28.1 +/- 10.3). It has to be emphasized that occasional patients with normally functioning valve prostheses can show unusual high gradients. Ring diameters between 21 and 27 mm showed no significant difference with regard to flow velocities and pressure gradients, whereas in 19-mm valves, significantly higher values could be demonstrated. The 123 aortic valve carriers with normal left ventricular function (fractional shortening greater than 25%) showed significantly higher pressure gradients than the 19 patients with reduced left ventricular function (28.6 +/- 11.6 mmHg vs 16.2 +/- 5.1 mmHg, p less than 0.05). In the mitral position, the mean of peak velocity (+/- SD) was 1.7 +/- 0.4 m/sec and pressure half-time was 108 +/- 26 msec, representing a calculated valve area between 1.4 to 3.1 cm2 (mean orifice size 2.1 +/- 0.5 cm2). No significant difference between valves of different sizes was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1992

[Pimobendan (UDCG 115 BS) in long-term therapy of chronic heart failure].

Pimobendan is a positive inotropic agent with additional calcium-sensitizing effects of the phosphodiesterase III-inhibitor group. In short-term studies, beneficial hemodynamic effects have been demonstrated in patients with congestive heart failure. The aim of this prospective study was to examine the long-term effect of pimobendan (during at least 6 months) on subjective state, hemodynamic parameters, and arrhythmias in patients with congestive heart failure NYHA classes II and III. After double-blind randomization, 24 patients received pimobendan 5 mg bid or placebo orally in addition to a basic therapy (diuretics, digitalis). After 3 months, pimobendan-treated patients showed a significant clinical improvement (p < 0.03). In the placebo group, one patient underwent acute cardiac transplantation due to rapid clinical deterioration; another patient died suddenly after 5 months. No cardiac events occurred in the pimobendan group. In comparison to placebo, no proarrhythmogenic effect of pimobendan was detected. Clinical stabilization of patients in the pimobendan group was not paralleled by improvement of the hemodynamic parameters of left-ventricular performance.

Cardiac Volume↗
PubMed1991

[Diagnosis of arrhythmogenic right ventricular disease using magnetic resonance tomography].

In our study, 12 patients with ventricular arrhythmias, but without any documented cardiac disease, and 10 healthy volunteers were investigated by spin echo magnetic resonance tomography (MRT) using a 0.5 Tesla magnet. Axial T1-weighted spin-echo sequences, as well as double angulated, multislice-multiphase sequences were acquired. Left- and right-ventricular volumes were then evaluated by outlining the endocardium in an end-systolic and an end-diastolic frame. The right-ventricular free wall and the right-ventricular outflow tract were investigated for myocardial thickness and intramural fat.

Adipose Tissue↗
PubMed1991

[Evaluating the function of aortocoronary bypasses with magnetic resonance tomography].

Following an aortocoronary bypass operation the differential diagnosis of chest pain of recent onset may be difficult (ischaemia, thoracotomy induced pain). At this point noninvasive methods are preferable to angiography in order to reach exact diagnosis. Magnetic Resonance Imaging (MRI), a new noninvasive imaging method, makes it possible to get anatomical and blood flow information without the use of ionizing radiation or contrast agents. It was the aim of our study to examine the diagnostic impact of MRI for the assessment of aortocoronary bypass graft patency. We compared three different acquisition techniques (a spinecho sequence and two fast-gradient echo sequences). 26 patients were examined, 49 bypass grafts were eligible for comparative evaluation. As compared with the spinecho technique, fast echo gradient sequences had a higher sensitivity (FISP 93%, FLASH 88%) than the spinecho technique 79%, and a higher accuracy (FISP 88%, FLASH 82%) versus 73%, respectively. We conclude that MRI may have a high diagnostic potential in the evaluation of early postoperative aortocoronary bypass graft patency.

Adult↗
PubMed1990

[Cine-MR for the quantification of regurgitation defects by a volume method].

We have examined 46 patients with angiographically confirmed regurgitant lesions (26 mitral insufficiency, 20 aortic insufficiency) using a 0.5 Tesla magnet. In each patient, multiplane and multiphase spin-echo sequences were obtained in a plane angled in the sagittal and coronal direction in the long axis of the heart; left and right ventricular volumes, ejection fractions and regurgitation fractions were calculated. In addition, a blood-flow sensitive gradient echo sequence was obtained in order to determine the direction and extent of the regurgitant jet. The data was compared with the results of angiography and echocardiography. By means of the gradient echo technique, MRI was able to show the regurgitant jet in every patient. There was a linear correlation between volumes determined by MRI and angiography. The best agreement was found for left ventricular contraction volume (R = 0.82, p is less than 0.0001). Comparison of the noninvasive and angiographic method showed a linear correlation for AI patients of R = 0.91 (p is less than 0.001), which is somewhat better than for patients with MI (R = 0.84, p less than 0.001). Semiquantitative grading of MI with a gradient echo technique showed a linear correlation with angiography of R = 0.73 (p less than 0.001), for AI there was agreement between both methods in 72% of cases. A comparison between MRI and colour Doppler sonography showed only moderately good correlation R = 0.69 (p less than 0.01).

Adult↗
PubMed1990

[MRT using Gd-DTPA in the diagnosis of tumor and pseudotumor intracardiac masses].

Magnetic resonance examinations were performed in 15 patients suffering from echocardiographically detected intracardiac masses. All patients were examined with a 1.5 T superconducting machine, using spin echo technique, including Gd-DTPA, and gradient echo sequences. The MR findings were confirmed partially by histology and angiography, otherwise by good correlation to clinical findings. MR results were divided into three groups: 1. tumour, 2. thrombosis, 3. pseudotumorous mass, and corresponded well with the final diagnosis: in 8 patients tumour, in 5 patients thrombosis, and in two patients pseudotumorous masses, including one hydatid cyst and one case of lipomatosis. Tumours showed in contrast to thrombosis marked enhancement after gadolinium injection, whereas the hydatid cyst and the lipomatosis demonstrated characteristic signal behaviour. Problems existed in differentiation mass vs slow flow, in the detection of very small masses, and in the assessment of wall-fixation and motion of a mass during cardiac cycle. The results demonstrate that MRI with Gd-DTPA can give important additional information in the differential diagnosis of echocardiographically detected intracardiac masses.

Adolescent↗
PubMed1990

Cardiac calcific deposits in patients with primary hyperparathyroidism: preliminary results of a prospective echocardiographic study.

To explain the incidence and significance of mitral and aortic valve calcification and calcific deposits in the myocardium, a prospective echocardiographic study was performed with 21 consecutive patients who had primary hyperparathyroidism (PHP) and with 21 age- and sex-matched control subjects with normocalcemia. Calcific deposits in the myocardium were seen in 13 patients (62%) with PHP, mainly in the interventicular septum, and in one control subject. Aortic valve calcification was observed in 12 patients (57%) with PHP and in one control subject. Calcification of the mitral valve was found in seven patients with PHP (33%) and three controls (14%). Calcification led to mild or moderate stenosis of the aortic valve in three patients with PHP and of the mitral valve in two patients with PHP. No stenosis was found in the subjects in the control group. Both calcification of the aortic and mitral valves and calcific deposits in the myocardium are common in patients with PHP and can be detected noninvasively by echocardiography. Because of the potential relationship of elevated calcium, calcification, and valvular heart disease, clinical evaluation of PHP should include echocardiographic studies before surgery is performed and during follow-up examination.

Adult↗
PubMed1989

24 hours electrocardiographic monitoring in obese children and adolescents during a 3 weeks low calorie diet (500 kcal).

Twenty-four hour electrographic recordings were made on 36 grossly obese children and adolescents during a 3-week weight reduction regimen with a 525 kcal (2196 kj) mixed diet at weekly intervals. One hundred and ten Holter ECGs were analysed. Weight loss during the treatment was calculated to be 5.7 +/- 1.6 kg. Average and minimal heart rate decreased constantly throughout the study period from 83.9 +/- 9 to 75 +/- 9/min and 53 +/- 6 to 45 +/- 6/min, respectively (P less than 0.01, P less than 0.005). During the second week maximal heart rate increased significantly but returned to baseline values in the third week. Neither before nor during the period of therapy were any dysrhythmias monitored. Dietary regimens containing 500-700 kcal, based on a mixed composition of foods with sufficient amounts of minerals, can be regarded as a safe therapeutic tool in the treatment of obese children and adolescents.

Adolescent↗
PubMed1989

Cine-MR in dissection of the thoracic aorta.

Magnetic resonance imaging (MRI) of the thoracic aorta, including cine-MRI, was performed in 25 patients suspected of having dissection of the thoracic aorta. MRI was correlated with echocardiography, CT and angiography. The sensitivity of MRI (100%) was most closely followed by CT and angiography (83% and 77% respectively). The specificity of MRI and angiography was equally good, at 100% each. MRI was able to demonstrate the intimal flap in all 9 cases of aortic dissection, and there were no false-positive results. Differentiation of thrombosis and slow flow was possible on proton density images, gradient echo images permitted detection of the entry and re-entry sites. The nature of the dissection was determinated correctly in 8 out of 9 cases. MRI is capable of providing all the relevant parameters necessary to decide appropriate treatment of dissecting aneurysms of the thoracic aorta.

Adolescent↗
PubMed1989

[Magnetic resonance tomography in the assessment of questionable aneurysm of the thoracic aorta with or without dissection of the intima].

To assess the value of MRI in the diagnosis of aneurysm of the thoracic aorta with suspected or known dissection 23 patients were imaged with cardiac gating. Seven patients (group 1) had known dissection of the thoracic aorta; in 16 patients (group 2) an aneurysm was suspected by chest x-ray or 2D-echocardiography. Reference methods were: x-ray, 2D-echocardiography, angiography, and computered tomography. In the first group MRI clearly identified the intimal flap, could differentiate between true and false lumen, slow flow, and thrombus, respectively. In the second group MRI could exclude a dissection of the ectatic part of the thoracic aorta in 11 patients and demonstrate paracardiac or mediastinal mass in five patients. MRI can serve as an important diagnostic tool in known or suspected aneurysm of the thoracic aorta.

Adolescent↗
PubMed1988

Prinzmetal's angina during cyclophosphamide therapy.

The first case of cyclophosphamide-induced myocardial ischaemia with electrocardiographically documented ST-segment elevation, T-wave inversion, arrhythmias, angina pectoris and cardiac decompensation is reported. The data suggest that cyclophosphamides induces myocardial ischaemia by eliciting coronary artery spasm.

Aged↗
PubMed1988

Survival rate and causes of death in patients with pacemakers: dependence on symptoms leading to pacemaker implantation.

The survival rate of 2256 patients with pacemakers was analyzed. Patients paced for Adams-Stokes equivalents (e.g. dizziness) showed a significantly better survival rate than did patients with pacemakers implanted for Adam-Stokes attacks or heart failure (P less than 0.0001). The estimated survival of the latter two groups did not differ significantly. Of the deceased patients who had received a pacemaker for the treatment of heart failure, 54% died due to this condition despite pacemaker implantation. The relative percentage of cases of sudden death after pacemaker implantation was high in the groups with Adams-Stokes attacks (12%) and Adams-Stokes equivalents (13%). In patients paced for Adams-Stokes attacks, sudden death occurred more frequently in the first year after pacemaker implantation (P less than 0.015) than during the following years. Therefore, increased efforts should be made to monitor patients carefully after pacemaker implantation to enable prompt detection of malignant tachyarrhythmias, probably the cause of sudden death in a substantial number of patients with pacemakers.

Adams-Stokes Syndrome↗
PubMed1987

Advantages of perfluorochemical perfusion in the isolated working rabbit heart preparation using 31P-NMR.

Quantitative 31P-NMR and enzymatic analysis of high-energy phosphates were used to characterize an isolated perfused working rabbit heart preparation. In this model, the left side of the heart works against a physiological after-load. Two perfusates, Krebs-Henseleit saline and the perfluorocarbon emulsion FC-43 (perfluorotributylamine), were evaluated in their ability to maintain cardiac function and high-energy phosphate metabolites over a period of 2-3 h. Adenine nucleotides ATP, ADP, phosphocreatine and inorganic phosphate (Pi) were measured by 31P-NMR while monitoring cardiac output and coronary flow. Intracellular pH was determined using the chemical shift of Pi. At the end of each experiment, hearts were freeze clamped and enzymatically assayed for adenine nucleotides, phosphocreatine and Pi. In every experiment, hearts perfused with FC-43 emulsion maintained the same rate of cardiac output as hearts perfused with Krebs-Henseleit saline, but with half the coronary flow rate: FC-43, 22 +/- 2.5 (n = 5), Krebs-Henseleit saline 42 +/- 2.7 (n = 6) ml/min, P less than 0.001. Hearts perfused with FC-43 emulsion showed higher [phosphocreatine] and [ATP] measured by 31P-NMR. For [phosphocreatine]: FC-43 3.2 +/- 0.7 (n = 5), Krebs-Henseleit saline 1.7 +/- 0.2 (n = 6) mumol/g wet wt., P less than 0.01. For [ATP]: FC-43 1.8 +/- 0.7 (n = 5), Krebs-Henseleit saline 0.9 +/- 0.2 (n = 6) mumol/g wet wt., P less than 0.02. [phosphocreatine] and [ATP] determined by 31P-NMR values were identical within experimental error to those values obtained by enzymatic analysis. Comparing [Pi] determined by both methods, 36% of Pi in FC-43-perfused hearts, and only 24% of Pi in Krebs-Henseleit saline-perfused hearts were visible by NMR, indicating that a large proportion of Pi is bound in the intact functioning heart. Similar results were obtained for [ADP]. Using the combined techniques of 31P-NMR and enzymatic assay, we have shown in this model of the isolated working rabbit heart preparation, that FC-43 emulsion maintains significantly better function and high-energy phosphate levels than Krebs-Henseleit saline.

Adenine Nucleotides↗
PubMed1985

[Intrapulmonary percussion. A new method of respiratory therapy].

Intrapulmonary percussion with a high-frequency jet system is a new method in the treatment of respiratory impairment. It imitates the conventional percussion massage of the thorax by introducing high-frequency gas oscillations (300 impulses per minute) into the tracheobronchial system. In 14 patients with abnormal alveolo-arterial oxygen differences due to bronchial mucostasis ventilation was satisfactorily improved by its application.

Humans↗