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Biomedical subjects

S Wieshammer

Publications and source records attributed to S Wieshammer.

18 recordsLinked to original sources
PubMed1992

Short-term reproducibility of gas exchange measurements during bicycle exercise in patients with mild to moderate congestive heart failure.

A series of 45 patients with congestive heart failure due to coronary disease had semisupine bicycle exercise tests (ramp protocol, 10 W/min) on two occasions separated by 3 to 7 days in order to determine the short-term reproducibility of gas exchange measurements during symptom-limited exercise. The percentage difference (PD) between each pair of measurements (m1, m2; PD = 100%.(m2-m1): m1) were calculated. The mean PD values (+/- 1 sigma) and the single determination standard deviations (SDSD) for exercise tolerance (ET, W), peak heart rate (pHR, 1/min), peak oxygen uptake (pVO2, ml/min/kg), peak carbon dioxide output (pVCO2, ml/min/kg), and peak minute ventilation (pVE, l/min) were as follows: [table: see text] No patient reached a plateau of oxygen uptake during the last portion of the ramp exercise test. Thus, pVO2 is not an objective endpoint. The single determination standard deviations show that exercise tolerance and peak oxygen uptake do not differ as to their reproducibility. The absolute values of PD were not a function of exercise tolerance for any of the parameters studied. The PD values for ET and pVO2 were normally distributed. The data suggest that a change in ET and pVO2 must exceed 27% and 28% between two sequential studies in an individual patient in order to be significant at the 5% level, respectively. For the one-tailed test situation, the changes in ET or pVO2 must be greater than 23% in order to be significant.

Adult↗
PubMed1991

Effects of atenolol, slow-release nifedipine, and their combination on respiratory gas exchange and exercise tolerance in stable effort angina.

The effects of atenolol, nifedipine, and their combination on gas exchange and exercise tolerance were studied in 27 patients with effort angina and normal global ventricular function in an open-label and randomized cross-over trial. Symptom-limited semi-supine exercise tests using a ramp protocol (20 W/min) with simultaneous breath-by-breath analysis of gas exchange were carried out after a 4-day wash-out period and after consecutive 2-week treatment periods with atenolol (50 mg b.i.d.), slow-release nifedipine (20 mg b.i.d.), and their combination (b.i.d.). Exercise tolerance was not significantly higher with atenolol than with nifedipine [118(24) vs 113(23) W]. Combination therapy [120(23) W] was more effective than monotherapy with nifedipine (p less than 0.05) but produced no further increase in exercise tolerance over atenolol monotherapy. Maximum oxygen uptake was not significantly different among the treatments. In the range of light to moderate exercise, the slope of the VO2-workload regression line expressed as ml.min-1.W-1 was lower with atenolol than with nifedipine [8.64(1.59) vs 10.28(1.74), p less than 0.005] and intermediate with combination therapy [9.99(1.83)]. The intercept on the VO2 axis was higher with atenolol than with nifedipine [366(111) vs 299(113) ml.min-1, p less than 0.05]. A similar pattern of results was seen when the drug effects on the slope of the VCO2-workload relation were analyzed. VE was higher with nifedipine than with atenolol at all points of the regression analysis [greater than 30 W].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

An unusual presentation of staphylococcal pericarditis.

An atypical presentation of purulent pericarditis caused by Staphylococcus aureus is described. A bacterial etiology was initially not taken into consideration because the clinical course was torpid and afebrile. Therefore, the appropriate treatment was delayed. The patient recovered after percutaneous pericardial drainage of his purulent pericardial effusion and antimicrobial therapy. The importance of a high index of suspicion of a bacterial cause in patients with pericardial effusion of unexplained etiology is emphasized.

Bacteriuria↗
PubMed1990

Hemodynamic profile of carvedilol.

Several so-called multiple-action compounds have been developed, such as medroxalol (alpha and beta blockade, and beta-2 stimulation), celiprolol (alpha-2 and beta-1 blockade, and beta-2 stimulation) and carvedilol (beta blockade and vasodilatation) for the treatment of patients with arterial hypertension and with coronary heart disease. Carvedilol exerts relatively uniform peripheral effects, i.e. a reduction of both systolic and diastolic blood pressure at rest and during exercise, and a decrease in the resting and exercise heart rate. Blood pressure fall due to carvedilol may be induced by its vasodilating effect, as documented by measurements of forearm blood flow and peripheral vascular resistance. Moreover, renal hemodynamics does not seem to be significantly altered by carvedilol. Carvedilol may also produce an improvement of the LV contractile status in patients with CHD and impaired LV function, mainly due to afterload reduction, in addition to its antianginal effect, which is due mainly to the beta-blocking properties of this substance. From the studies mentioned it may be concluded that carvedilol is a useful and promising drug for treating patients with both arterial hypertension and with coronary artery disease.

Adrenergic beta-Antagonists↗
PubMed1990

Effects of hypothyroidism on bronchial reactivity in non-asthmatic subjects.

The effect of hypothyroidism on non-specific bronchial reactivity was studied in 11 patients without pulmonary disease (mean age 40 (SD 13) years) who had had a total thyroidectomy and radioiodine treatment for thyroid cancer 41 (36) months before the study. All patients when mildly hyperthyroid while having long term thyroxine replacement treatment and once when hypothyroid two weeks after stopping triiodothyronine for the purpose of screening for metastases. Bronchial reactivity was assessed by measuring specific airways conductance (sGaw) after increasing doses of inhaled carbachol (45-1260 micrograms). The dose producing a 35% decrease in sGaw (PD35) was determined from the cumulative log dose-response curve by linear regression analysis. Mean baseline sGaw values were similar when the patients were hypothyroid and when they were hyperthyroid (1.35 (0.36) and 1.41 (0.56) s-1 kPa-1). The interstudy coefficients of variation of baseline sGaw were higher in the thyroid patients than in a euthyroid control group (14% versus 8%). Geometric mean PD35 was lower when the patients were hypothyroid (97 micrograms) than when they were mildly hyperthyroid (192 micrograms). It is concluded that acute hypothyroidism increases non-specific bronchial reactivity in nonasthmatic subjects.

Acute Disease↗
PubMed1990

[The role of radionuclide ventriculograms in determining the indications for valve replacement in chronic aortic valve insufficiency].

Timing of aortic valve replacement (AVR) in chronic aortic regurgitation (AR) remains a difficult problem in clinical practice. Radionuclide ventriculography (RNV) yields information on the extent of valvular regurgitation, the enlargement and the systolic function of the left ventricle. A "well-timed" AVR is defined by 1) postoperative improvement of clinical symptoms, decrease in left ventricular end-diastolic volume (EDV) and normalization of ejection fraction (EF) as well as by 2) greater improvement under surgical therapy as compared to conservative management. In "too early" AVR the latter condition is not fulfilled, while in "too late" AVR the first condition is not accomplished. In this study 54 patients with chronic aortic incompetence were evaluated by RNV to see whether these three groups ("too early", "well timed", "too late" AVR, resp.) can be separated by the relation between EDV and regurgitant volume (RV), the level of the EDV and the clinical status. The examination was based on pre- and postoperative RNV studies as well as on follow-up studies. A good postoperative result can be expected in cases with a preoperative EDV/RV-ratio similar to that observed in 30 patients with AR in whom AVR was not indicated. In contrast, in the majority of those cases with an EDV/RV-ratio exceeding this normal range the postoperative outcome will be unsatisfactory. If the EDV/RV-ratio is normal, AVR should be performed in cases with an EDV exceeding 400 ml, while in cases with an EDV between 300-400 ml AVR is only indicated in the presence of additional symptoms (NYHA greater than or equal to II).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Acute hypothyroidism has no effect on pulmonary vascular resistance.

The effect of acute hypothyroidism on the pulmonary circulation was studied in 9 nonobese athyreotic patients by right heart catheterization at rest and during exercise. The patients were studied while they were hypothyroid 2 weeks after ceasing triiodothyronine treatment and while they were euthyroid on replacement therapy. At rest, pulmonary blood flow [4.0 +/- 0.6 l/min vs 5.8 +/- 1.0 l/min, p less than 0.01] and systolic pulmonary artery pressure [18 +/- 3 mmHg vs 23 +/- 2 mmHg, p less than 0.01] were lower when the patients were hypothyroid than when they were euthyroid. The mean and diastolic pressures in the pulmonary artery and the pulmonary capillary pressures were not different among the groups. Likewise, thyroid hormone levels had no significant effect on pulmonary vascular resistance [100 +/- 25 dyn-s-cm-5 vs 90 +/- 23 dyn-s-cm-5]. With supine exercise, pulmonary blood flow [10.1 +/- 1.6 l/min vs. 13.2 +/- 2.0 l/min, p less than 0.01], mean pulmonary artery pressure [25 +/- 6 mmHg vs 30 +/- 6 mmHg, p less than 0.02], and systolic pulmonary artery pressure [36 +/- 6 mmHg vs 44 +/- 8 mmHg, p less than 0.01] were lower when the patients were hypothyroid. The diastolic pulmonary artery pressure and the pulmonary capillary pressure were similar in both thyroid states. Again, thyroid deficiency had no effect on pulmonary vascular resistance [81 +/- 23 dyn-s-cm-5 vs 76 +/- 24 dyn-s-cm-5]. The lower systolic pressures in the pulmonary artery seen in hypothyroidism are probably due to the decreased systolic volume load of the pulmonary circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Acute hypothyroidism slows the rate of left ventricular diastolic relaxation.

The effect of acute thyroid hormone deficiency on left ventricular diastolic filling was studied by radionuclide ventriculography with simultaneous right heart catheterization in nine athyreotic patients without cardiovascular disease. The patients were studied when they were hypothyroid and when they were euthyroid on replacement therapy. Peak filling rate and the time to peak filling were used to characterize diastolic function. The time to peak filling was defined as the interval from end-systole on the radionuclide time-volume curve to the time of occurrence of peak filling. The peak filling rate was determined in absolute terms from the normalized radionuclide peak filling rate and from the end-diastolic volume, which was derived from the radionuclide ejection fraction and from the thermodilution stroke volume. In all patients, the values for peak filling rate were lower in the hypothyroid than in the euthyroid state (287 +/- 91 mL/s vs. 400 +/- 118 mL/s, delta = 41 +/- 13%, p less than 0.01). Peak filling always occurred during the first half of the diastolic interval. The time to peak filling was not significantly affected by the thyroid state (170 +/- 10 ms vs. 159 +/- 21 ms, delta = 7 +/- 10%). Left ventricular filling pressure as reflected by the pulmonary capillary wedge pressure and end-systolic volume were similar in both thyroid states (6 +/- 2 mmHg vs. 8 +/- 2 mmHg (1 mmHg = 133.32 Pa) and 32 +/- 11 mL vs. 32 +/- 7 mL, respectively). The data suggest that the rate of active diastolic relaxation is decreased in short-duration hypothyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Left ventricular function at rest and during exercise in acute hypothyroidism.

The effect of hypothyroidism on left ventricular function at rest and during exercise was studied in nine patients without demonstrable cardiovascular disease who had had total thyroidectomy and ablative radioiodine treatment for thyroid cancer. Radionuclide ventriculography and simultaneous right heart catheterisation were performed while the patients were hypothyroid two weeks after stopping triiodothyronine treatment (to permit routine screening for metastases) and while they were euthyroid on thyroxine replacement treatment. When the patients were hypothyroid, cardiac output, stroke volume, and end diastolic volume at rest were all lower and peripheral resistance was higher than when they were euthyroid. Pulmonary capillary wedge pressure, right atrial pressure, heart rate, left ventricular ejection fraction, and the systolic pressure:volume relation of the left ventricle, which was used as an estimate of the contractile state, were not significantly different when the patients were hypothyroid or euthyroid. During exercise, heart rate, cardiac output, end diastolic volume, and stroke volume were higher when the patients were euthyroid than when they were hypothyroid. Again, pulmonary capillary wedge pressure, ejection fraction, and the systolic pressure:volume relation were similar in both thyroid states. The data suggest that the alterations in cardiac performance seen in short term hypothyroidism are primarily related to changes in loading conditions and exercise heart rate; they do not suggest that acute thyroid hormone deficiency has a major effect on the contractile properties of the myocardium.

Acute Disease↗
PubMed1988

Relation of pressure and flow of pulmonary circulation in patients with chronic obstructive pulmonary disease.

A series of 31 patients with various degrees of chronic obstructive pulmonary disease underwent right heart catheterization using flow-directed thermodilution catheters. Both rest and supine exercise values were obtained. The patients were divided into two groups on the basis of their reduction in forced expiratory volume in 1 s (FEV1). In patients with FEV1 values of greater than or equal to 1,300 ml (group 1), the arterial oxygen partial pressure (PaO2) did not significantly change with exercise, while in patients with FEV1 of less than or equal to 1,200 ml (group 2) PaO2 significantly (p less than 0.05) fell in response to exercise. In group 2, a significant increase of total pulmonary resistance (TPR) with exercise was found (p less than 0.01). Pulmonary vascular resistance (PVR) remained unchanged in both subgroups. It is suggested that the value of PVR for subgroup 2 is artificially low because an important variable, namely pulmonary artery wedge pressure, is influenced by alveolar pressure in patients with an uneven distribution of perfusion and ventilation at pulmonary venous pressures lower than alveolar pressure. The steeper slope of the pressure-flow relationship in these patients is probably due to an increased vascular tone caused by chronic hypoxia at rest and further fall of PaO2 and rise of arterial CO2 partial pressure in response to exercise.

Adult↗
PubMed1987

Radionuclide ventriculography and hemodynamic evaluation by right heart catheterization with exercise for assessing the functional significance of coronary artery stenoses. A comparative study.

A series of 13 patients with significant coronary stenoses but without prior myocardial infarction were simultaneously studied by right heart catheterization and radionuclide ventriculography to determine the extent to which abnormal responses in left ventricular ejection fraction and wall motion to maximum exercise are paralleled by abnormal left ventricular filling pressures. The correlations of the filling pressure as evaluated by the diastolic pulmonary artery pressure with both the exercise ejection fraction and the rest-to-exercise change in ejection fraction were high (r = -0.89, P less than 0.01 and r = -0.76, P less than 0.01, respectively). In addition, the filling-pressure response to stress separated the patients into distinct radionuclide categories. All the 7 patients with grossly abnormal filling pressures (P greater than or equal to 30 mmHg) developed regional wall motion abnormalities with exercise as evaluated by visual interpretation or quantitative phase analysis. These patients also had a decrease in ejection fraction from rest to exercise ranging from -9% to -32% together with an exercise ejection fraction below 50%. Conversely, these abnormalities were never found in patients with filling pressures below this threshold level. The data suggest that radionuclide ventriculography and measurement of left ventricular filling pressure with exercise yield corresponding results when assessing the functional significance of coronary stenoses in normotensive patients without prior myocardial infarction and normal global left ventricular function at rest.

Blood Pressure↗
PubMed1987

Effect of right ventricular hypertrophy on cardiac performance and the relation between right ventricular systolic peak pressure and end-systolic volume.

To investigate the role of hypertrophy of the right ventricle upon right heart performance and the significance of the peak systolic pressure/end-systolic volume (P/V) ratio in terms of right ventricular systolic performance, simultaneous measurements of radionuclide ventriculograms and central hemodynamics were done in 32 patients with chronic obstructive pulmonary disease. In 26 of the patients (80%) technically adequate two-dimensional echocardiograms could be performed. In the subset of patients with increased (greater than or equal to 6 mm) right ventricular end-diastolic wall thickness no relationship between pulmonary artery pressure and right ventricular ejection fraction (RVEF) existed in comparison with the remaining patients. P/V indices and cardiac output were not decreased. Considering the patients, whose P/V ratio did not increase from rest to exercise, RVEF decreased highly significantly more than in the remaining patients. The ratio of wall thickness and end-diastolic radius as determinant of peak systolic stress was significantly decreased in these patients compared with the remaining patients. In the patients with right ventricular hypertrophy despite significantly higher values of pulmonary artery pressures and resistances, the afterload in terms of systolic wall stress is markedly reduced. We conclude that in the hypertrophic state, right ventricular performance is not impaired despite decreased RVEF values. In the patients whose P/V ratio does not increase from rest to exercise, an inappropriate high peak systolic wall stress may exist both due to inadequate wall thickness and increased diameter of the right ventricle. The role of P/V in terms of prognosis and development of decompensated right heart failure remains undetermined.

Biomechanical Phenomena↗
PubMed1987

[Radionuclide ventriculography--a noninvasive method of diagnosis and quantification of tricuspid valve insufficiency].

The diagnosis of tricuspid regurgitation (TR) is difficult to make by simple clinical methods or by invasive techniques. Contrast echocardiography and Doppler echocardiography have improved diagnostic results, but a golden standard is still not available. Radionuclide ventriculography (RNV) is a well-established method for the detection and quantification of a volume load on the left ventricle: the regurgitation fraction can simply be derived from the regurgitant index as the ratio of enddiastolic-endsystolic count-rate differences between the left and right ventricle. In left heart valvular regurgitation a regurgitant index exceeding the upper normal limit can be expected. This study was performed to evaluate the diagnostic accuracy of an abnormally low regurgitant index in detecting TR, which is accompanied by an isolated volume load on the right ventricle. A series of 33 patients with TR on physical examination and cardiac catheterization underwent RNV and was compared with 48 patients with right ventricular enlargement or pressure load on the right ventricle. In addition, the specificity of the method was evaluated in 470 consecutive patients with various forms of heart disease. In 18 out of 20 subjects with isolated TR a regurgitant index below the lower normal limit was found. The remaining 2 cases with minor TR had a regurgitant index within the normal range, which is 0.89 to 1.97 in this laboratory. In patients with additional volume load on the left ventricle, the sensitivity of the method was found to be low, as could be expected from the principle of the method. The time-activity curve over the liver was usually in phase with that recorded over the atria in subjects with TR. Therefore, the additional examination of a region of interest over the liver was particularly useful in these patients with concomitant aortic or mitral valve regurgitation. None of the 48 patients with right ventricular enlargement or pressure load on the right ventricle had a falsely positive result. A total of 17 out of 470 consecutive patients had a regurgitant index below the normal range; left ventricular function was severely impaired in 9 of these patients. The remaining subjects had a regurgitant index slightly below the lower normal limit. In conclusion, RNV has a high sensitivity in the diagnosis of TR in patients without left heart valvular regurgitation and a high specificity in patients without severely impaired left ventricular function and without left-to-right shunt through an atrial septal defect.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1986

Left heart function in chronic obstructive lung disease.

In patients with varying degrees of chronic obstructive pulmonary disease (COPD), simultaneous measurements of central hemodynamics and left ventricular radionuclide ventriculograms at rest and during exercise were made. In 21 of these patients, satisfactory echocardiograms could be performed. In seven of the patients, arterial blood pressure at rest was increased. Decreased compliance of the left ventricle was thought to be present in patients with COPD and additional arterial hypertension. The left ventricular ejection fraction (LVEF) at rest was in the high normal range in all patients. During exercise, no further increase was observed. This pattern of LVEF response seems to be typical in patients with COPD. Because the highest values were observed in the more severe COPD and right ventricular hypertrophy, it is unlikely that an impairment of left ventricular function is caused by COPD. In five of 27 patients, an abnormal decrease of LVEF and regional hypokinesis occurred during exercise, thus suggesting additional coronary heart disease. The fact that at least 30% of the patients with COPD suffered from arterial hypertension and 20% of the patients exhibited unexpected ischemia detected by regional hypokinesis in RNV during exercise, but not in the ECG, may be of practical relevance. Coronary angiography was not indicated because most of these patients were over 65 and the factor limiting the working capacity was ventilatory impairment and not angina pectoris, in all patients. For this reason, a diagnostic uncertainty remains with regard to additional coronary heart disease in the older patients with advanced chronic obstructive pulmonary disease.

Aged↗
PubMed1986

Haemodynamic response to exercise in patients with chest pain and normal coronary angiograms.

A series of 42 patients with chest pain but normal coronary angiograms and normal haemodynamics at rest were prospectively classified as typical angina (group 1, N = 9) or atypical angina (group 2, N = 16) or non-anginal chest pain (group 3, N = 17). All patients underwent radionuclide ventriculography and measurement of pulmonary artery pressure at rest and during maximum exercise. Comparison of data during exercise revealed significantly higher (P less than 0.025) left ventricular filing pressures as reflected by the diastolic pulmonary artery pressure in group 1 (29 +/- 5 mmHg) than in both group 2 (22 +/- 6 mmHg) and group 3 (22 +/- 5 mmHg). The rest-to-exercise change in left ventricular ejection fraction was variable and not significant in group 1 (62 +/- 6% vs 63 +/- 14%). By contrast, both group 2 and group 3 had significant increases (63 +/- 6% vs 69 +/- 10%, P less than 0.02 and 63 +/- 5% vs 68 +/- 5%, P less than 0.01). The classification as 'typical angina' was predictive of an abnormal (greater than 25 mmHg) filling-pressure response to stress. The positive and negative predictive values were 78% and 70%, respectively. The clinical classification was not a predictor of an abnormal (delta less than 5%) ejection-fraction response. No correlation between radionuclide and filling-pressure data could be established. The data suggest that the majority of patients assigned to group 1 manifested an impaired left ventricular function with exercise. This was primarily related to abnormalities in diastolic filling while the systolic performance was not consistently depressed.

Adult↗
PubMed1985

Limitations of radionuclide ventriculography in the non-invasive diagnosis of coronary artery disease. A correlation with right heart haemodynamic values during exercise.

A consecutive series of 56 patients with chest pain but no evidence of previous myocardial infarction was prospectively studied by radionuclide ventriculography to determine the value of global and regional radionuclide indices in detecting coronary artery disease. The results were correlated with the clinical judgment of chest pain, the results of the exercise electrocardiogram, and the right heart haemodynamic measurements during exercise. As a result of the criteria for entry, the study group was representative of the population seen in such a clinical setting. Only 25% of patients had coronary artery disease. The predictive power of radionuclide ventriculography was limited. The conventionally used criterion that normal subjects have an increase in left ventricular ejection fraction of at least 5% with exercise provided only 78% sensitivity and 57% specificity. Fourier analysis and visual interpretation of radionuclide studies wrongly diagnosed three out of 10 patients with extensive disease requiring surgery. These results suggest that radionuclide ventriculography is of limited value in the non-invasive diagnosis of coronary artery disease.

Adult↗