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Biomedical subjects

L Rudas

Publications and source records attributed to L Rudas.

At least 55 records · Page 3Linked to original sources
PubMed1992

Hemodynamic observations following orthotopic cardiac transplantation: hemodynamic responses to upright exercise at 1 year.

Central hemodynamic responses during upright exercise were studied at 1 year in 40 orthotopic cardiac transplant recipients. Hemodynamic responses were characterized by slow rise in heart rate and blunted peak exercise heart rate response, a significant early increase in stroke index followed by a plateau phase, and a steady increase in ventricular filling pressures and pulmonary artery pressure. In spite of exclusive utilization of the Frank-Starling mechanism to augment cardiac output during early exercise, the pressure responses were comparable to those reported in normal subjects. Our observations also indicate that similarly to normal subjects, the heart rate response plays an important role in the cardiac output achieved at maximum exercise. Although patients with younger donor hearts achieved a more favorable maximum heart rate, the other hemodynamic parameters showed no correlation with the donor heart age. Thus, no hemodynamic disadvantage of older donor hearts could be demonstrated. These data provide further enlightenment regarding the mechanisms of the well-preserved functional capacity noted in these patients.

Adult↗
PubMed1992

Hemodynamic observations following orthotopic cardiac transplantation: evolution of rest hemodynamics in the first year.

The evolution of resting hemodynamics was studied at 1 week and 1 year in 40 patients following orthotopic cardiac transplantation. Abnormal hemodynamics after transplantation, characterized by elevated ventricular filling pressures (indicating diastolic dysfunction) and also by pulmonary hypertension, showed normalization by 1 year. In the absence of innervation, the resting heart rate of heart transplant recipients should theoretically be close to the intrinsic heart rate predicted by the age of the donor heart. In this study, a high incidence of relative sinus bradycardia (an indicator of sinus node dysfunction) was noted in the first post-operative week, although again there was a tendency to normalization by 1 year. These beneficial changes help to explain the dramatic and sustained improvement in the functional capacity of these patients late after transplantation.

Adult↗
PubMed1992

Vasodepressor syncope in a cardiac transplant recipient: a case of vagal re-innervation?

At the time of hemodynamic assessment three years after cardiac transplantation, a patient developed symptoms and signs of a vasodepressor reaction. In addition to sudden deceleration of heart rate, a 26% fall in mean blood pressure and a 36% fall in cardiac output was observed. Subsequent investigations revealed the presence of respiratory sinus arrhythmia, profound heart rate acceleration on standing and an approximately normal heart rate response during the following exercise. Contrary to current thinking, these observations suggest that certain individuals may develop autonomic re-innervation following orthotopic cardiac transplantation.

Adult↗
PubMed1991

Evolution of heart rate responsiveness after orthotopic cardiac transplantation.

Although anatomic reinnervation of the donor heart is unlikely after transplantation, individual subjects have been noted to show near physiologic heart rate (HR) responses to exercise. To assess development of this phenomenon, we studied HR changes in response to orthostasis and treadmill exercise in 52 orthotopic cardiac transplant recipients grouped according to time after transplantation. In group 1 (2.0 +/- 0.9 months), no significant increase in HR was seen up to 100 cardiac cycles after standing. A maximal acceleration of 4.0 +/- 3.8 beats was seen within 100 cardiac cycles after standing in group 2 (15.8 +/- 5.6 months). Patients in group 3 (42.4 +/- 12.4 months) showed significant cardioacceleration by 5 cardiac cycles after standing to a maximum of 10.7 +/- 5.8 beats/min within the first 100 cardiac cycles. During exercise, HR increased more rapidly during the first minute in group 3 compared with group 1 (p less than 0.01). After exercise, HR continued to increase in group 1 but decreased rapidly in the other groups, most notably group 3 (-26.5 +/- 16.5 by 2 minutes, p less than 0.0001 vs groups 1 and 2). These data indicate development of functional reinnervation after orthotopic heart transplantation. The phenomenon of early acceleration of the HR after orthostasis and rapid deceleration after exercise in transplant recipients implies a local cardiac mechanism rather than response to circulating catecholamines.

Adolescent↗
PubMed1990

Serial evaluation of lipid profiles and risk factors for development of hyperlipidemia after cardiac transplantation.

To determine the prevalence, time course and factors responsible for hyperlipidemia after heart transplantation, 83 consecutive 1-year survivors were studied. By 1 year, 83% of patients had serum total cholesterol levels greater than 5.2 mmol/liter (200 mg/dl) and 28% of the patients had serum total cholesterol higher than the age- and sex-matched ninety-fifth percentile. At the end of 1-year follow-up, serum total cholesterol correlated with the recipient age (p less than 0.0001), the preoperative cholesterol level (p less than 0.001), the actual dose of maintenance prednisone at 1 year (p less than 0.02) and the cumulative 1-year steroid dose (p less than 0.03). Similarly, the serum triglyceride level at 1 year correlated with the pretransplant level of serum triglycerides (p less than 0.0001), recipient age (p less than 0.03) and cumulative 1-year steroid dose (p less than 0.03). Patients with a pretransplant diagnosis of coronary artery disease had a significantly higher level of serum total cholesterol and triglyceride levels at 1 year (p less than 0.02 and p less than 0.03, respectively). Heart transplant recipients with body mass index greater than or equal to 25 kg/m2 also presented with significantly elevated serum total cholesterol and triglyceride levels at 1 year compared with nonobese patients (p less than 0.01 and p less than 0.002, respectively). Hyperlipidemia occurs frequently and is detected within the first month after heart transplantation. Optimal management of this problem requires further study.

Adolescent↗
PubMed1990

Comparison of hemodynamic responses during dynamic exercise in the upright and supine postures after orthotopic cardiac transplantation.

Abnormal hemodynamic responses during supine exercise have been well documented in orthotopic cardiac transplant recipients. To determine the effect of posture, central hemodynamics were studied in 20 patients during a change from supine to sitting and during graded upright bicycle exercise (group U) and were compared with those of 20 patients matched for age, gender and time from transplantation who were studied after passive leg elevation and during exercise in the supine posture (group S). Passive leg elevation resulted in a 9% increase in stroke index (34 +/- 6 to 37 +/- 6 ml/m2, p less than 0.001) and a 10% increase in cardiac index (3.1 +/- 0.4 to 3.4 +/- 0.5 liters/min per m2, p less than 0.001) in group S patients compared with a 15% reduction in stroke index (34 +/- 7 to 29 +/- 6 ml/m2, p less than 0.001) and a 9% decrease in cardiac index (3.2 +/- 0.6 to 2.9 +/- 0.5 liters/min per m2, p less than 0.001) in group U patients on assuming the sitting posture. Likewise, both the pulmonary capillary wedge pressure and right atrial pressure increased significantly (13 +/- 4 to 17 +/- 8 mm Hg, p less than 0.001 and 5 +/- 3 to 7 +/- 3 mm Hg, p less than 0.001) with passive leg elevation in group S and decreased on sitting (12 +/- 6 to 8 +/- 5 mm Hg, p less than 0.001 and 5 +/- 3 to 3 +/- 2, p less than 0.001) in group U.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Depressed baroreflex sensitivity in patients with Alzheimer's and Parkinson's disease.

Parkinson's disease (PD) and Alzheimer's dementia (AD) are often associated with an autonomic neuropathy. The extent of autonomic involvement, however is poorly defined and unpredictable. In order to assess the autonomic cardiovascular regulation baroreflex sensitivity (BRS) was determined non-invasively in 23 patients (age: 65 +/- 9.3 years) with PD and 24 patients with AD (age: 72.3 +/- 7.2 years). The results were compared with those on 22 healthy age- and sex-matched volunteers. Patients with PD and AD exhibited marked abnormalities in cardiovascular autonomic reflex regulation showed by markedly depressed BRS. The possible predictive value of centrally based depression of baroreflex sensitivity necessitates further studies.

Aged↗
PubMedDate not supplied

Isometric handgrip exercise-induced muscarinic vasodilation in the human skin microvasculature.

The existence of an active vasodilator system in the human skin microvasculature is well documented, but its physiological role and the underlying mechanisms are not completely understood. Cutaneous blood flow increases during isometric handgrip exercise. To examine whether this response is mediated by active vasodilation, isometric handgrip exercise testing was performed in nine healthy subjects. Local iontophoresis of atropine was applied to the forearm skin. Skin blood flow (SBF) monitoring by means of laser Doppler flowmetry was combined with continuous noninvasive blood pressure monitoring. SBF monitoring was performed at a site pretreated with atropine and an adjacent control area. Mean arterial pressure (MAP) was recorded noninvasively. Cutaneous vascular resistance (CVR) was calculated as MAP/SBF for the atropine treated and the control areas. Changes in CVR were expressed as percent deviation from the baseline (dCVR). Isometric handgrip exercise resulted in a marked reduction in CVR at the control site (dCVR: -66 +/- 4%). In contrast, the CVR was not significantly altered at the atropinetreated site (2.4 +/- 7%). It is concluded that isometric exercise induces an atropine-sensitive vasodilation which is mediated by muscarinic receptors in the human skin.

Adult↗
PubMedDate not supplied

Concretions in renal basement membranes.

A study of 196 renal biopsies was carried out by electron microscopy. In 78 cases concretions were detected, which x-ray microanalysis (EDAX) proved to be calcium phosphate deposits. Concretions always occurred in damaged basement membranes, especially in the basement membranes of Bowman's capsules and of proximal convoluted tubules. They were frequently also found in sclerotic foci. Both nephrotic syndrome (through hypercholesterolaemia) and progressive sclerotic processes seem to play a role in the pathogenesis of concretion formation. Concretions are considered to represent early dystrophic calcification.

Basement Membrane↗
PubMedDate not supplied

Cholesterol-lowering therapy after heart transplantation: a 12-month randomized trial.

BACKGROUND: Hypercholesterolemia, a common problem after heart transplantation, may be important in the genesis and progression of allograft coronary artery disease. The current study was performed to compare the efficacy of gemfibrozil, simvastatin, and cholestyramine for cholesterol lowering in heart transplant recipients. METHODS: In this prospective 1-year study, 48 heart transplant recipients with moderate hypercholesterolemia were randomized to therapy with gemfibrozil 600 mg twice daily (n = 17), simvastatin 10 mg daily (n = 13), and cholestyramine 4 gm twice daily (n = 18). Detailed lipoprotein analysis was performed at baseline and after 3, 6, and 12 months of treatment. RESULTS: Total cholesterol and low-density lipoprotein cholesterol were reduced 19% and 29%, respectively, after 3 months of simvastatin therapy (p < 0.0001) with a sustained reduction in total cholesterol (25%) and low-density lipoprotein cholesterol (39%) at 1 year. Gemfibrozil and cholestyramine treatment did not result in a reduction in cholesterol levels. Apolipoprotein B levels were reduced by 29% at the end of 1 year with simvastatin but not with the other treatments. Serum triglyceride levels were reduced significantly by treatment with gemfibrozil (up to 36%, p < 0.01) but not by the other treatments. High-density lipoprotein cholesterol initially rose in patients treated with simvastatin and gemfibrozil; however, this effect did not persist to 12 months. However, the ratio of low-density lipoprotein/high-density lipoprotein was favorably affected by simvastatin, with a 38% reduction by 12 months (p < 0.0001) but not by the other treatments. Over the course of 1 year, 14 patients dropped out of the study: four from the gemfibrozil arm and ten from the cholestyramine arm. Gastrointestinal intolerance was the most common reason for study termination (8 of 14). All patients in the simvastatin treatment arm completed 12 months of therapy. No biochemical abnormalities resulted from any therapy, and no therapy caused significant alteration in cyclosporine blood levels. CONCLUSIONS: Of the three therapies studied, simvastatin was found to be the most efficacious and well tolerated for cholesterol lowering in patients after heart transplantation.

Adult↗