Search PubMed⌕ Search

Biomedical subjects

W Bleifeld

Publications and source records attributed to W Bleifeld.

At least 127 records · Page 7Linked to original sources
PubMed1985

[Intraoperative monitoring using transesophageal 2-dimensional echocardiography].

Currently used monitoring techniques, such as measurements of blood pressure and heart rate, provide incomplete information about cardiac function during surgery. Invasive monitoring like intraoperative pulmonary artery pressure measurement with flow-directed balloon catheters may be more sensitive to detect cardiac instability, but they are associated with potentially fatal complications such as dysrhythmias and pulmonary artery rupture. In search of a more informative and yet safe intraoperative hemodynamic monitoring system, we have investigated the use of 2-D transoesophageal echocardiography (TEE). So far more than 400 patients were studied by TEE for up to 12 hours during elective surgery without any complications. High quality recordings of the left ventricle (LV) could be obtained in 87% of all patients. On the basis of the results presented below, we believe that TEE holds three fundamental advantages over the existing monitoring systems: it is inherently safer than intravascular measures, it allows direct assessment of LV filing, and it provides direct information on global and regional LV wall motion.

Abdomen↗
PubMed1985

[Color-coded 2-dimensional Doppler echocardiography. Initial clinical experiences].

A new technology based on the Doppler principle for ultrasound has recently enabled the real-time visualization of cardiac blood flow by superposition of coloured flow information onto a two-dimensional echocardiogram. This study presents typical flow patterns in standard echocardiographic views, obtained from normal subjects and patients with acquired valvular or congenital heart diseases. Diagnostic possibilities and limitations of colour-coded Doppler echocardiography are discussed.

Adult↗
PubMed1984

[Possible prevention of adriamycin-induced cardiomyopathy by verapamil. Results of a pilot study].

An increased cytoplasmatic calcium level seems to play an important role in the pathogenesis of Adriamycin (ADM)-induced cardiomyopathy. Experiments have shown that calcium channel blockers such as verapamil may prevent this type of cardiomyopathy in animals, but data are contradictory. In a clinical pilot trial, the left ventricular function of 22 patients undergoing ADM-chemotherapy in combination with verapamil was examined. M-mode echocardiograms were performed parallel to every chemotherapy course. Left ventricular function was determined by fractional shortening rate (FS) and peak fibre shortening velocity (V ef max.). Three 40-mg doses of verapamil were given p.o./day continuously. Data of these patients were compared with a control group of 61 patients treated and checked equally without additional verapamil therapy. In the course of therapy parameters of left ventricular function remained almost constant in the verapamil group but decreased significantly in the control group. In the verapamil group FS changed by -0.05 FS %/100 mg ADM/m2, V ef max. by +0.015 circ./s/100 mg ADM/m2 compared with -2.31 FS % and -0.33 circ./s in the control group (P 0.01 and 0.001, respectively). In the verapamil group no congestive heart failure occurred and no patient showed FS below 30%, whereas in the control group in 23% (14) of the cases ADM therapy had to be stopped because FS fell below 30%. One congestive heart failure was observed. These clinical results suggest that verapamil may be a useful drug for preventing ADM-induced cardiomyopathy but further investigations are necessary.

Cardiomyopathies↗
PubMed1984

Tachycardia prevention by programmed stimulation.

Ten patients with an atrioventricular accessory pathway were studied by standard electrophysiologic techniques to determine if reentrant tachycardia can be prevented in these patients by delivery of a single extrastimulus, applied at a critical time after the tachycardia-initiating stimulus (or stimuli). In all 10 patients, reentrant tachycardia was reproducibly induced from the high right atrium with a single premature beat, and initiation of tachycardia could be prevented from the same site by a second premature beat. This second extrastimulus was effective if delivered within a zone that began 10 ms outside of the effective refractory period of the tachycardia-initiating stimulus and averaged 50 ms in width. This zone was termed the "preventive zone." The width of the preventive zone was independent of the initial tachycardia interval and the tachycardia cycle length. Prevention of reentrant tachycardia was always possible with a single atrial extrastimulus, whereas termination of the ongoing tachycardia required at least 2 atrial extrastimuli or stimulation from the right ventricle.

Adolescent↗
PubMed1984

Electrophysiologic and clinical effects of intravenous and oral encainide in accessory atrioventricular pathway.

The effect of intravenous and oral encainide was studied in 12 patients with an accessory atrioventricular pathway (AP). Eight patients had Wolff-Parkinson-White syndrome and 4 had a concealed AP. Electrophysiologic studies were performed before and after intravenous encainide, 1.0 to 1.5 mg/kg, and 4 weeks after oral encainide, 75 to 200 mg/day. Mean follow-up was 19 +/- 6 months. During sinus rhythm, intravenous and oral encainide significantly prolonged the AH and HV intervals. In patients with Wolff-Parkinson-White syndrome, after intravenous encainide, anterograde conduction over the AP was blocked in 3 patients, and the anterograde effective refractory period (ERP) of the AP was markedly increased in 3. Five of these 6 patients had a control value of the anterograde AP ERP of less than 270 ms. Anterograde AP block was maintained in 2 patients after oral encainide therapy. Retrograde AP block or marked increase of retrograde AP ERP was seen in 4 of 9 patients after intravenous encainide and in 2 of 7 after oral therapy. Encainide either prevented induction of circus movement tachycardia (intravenous, 4 of 11 patients; oral, 2 of 7 patients) or significantly prolonged tachycardia cycle length (intravenous, 7 of 11 patients; oral, 5 of 7 patients). During long-term follow-up of 9 patients, 6 patients had no recurrences of tachyarrhythmia after individual adjustment of encainide dosage. One patient had worsening of supraventricular tachycardia after intravenous encainide therapy and 4 patients complained of visual blurring; in 1 patient it was so severe that it required withdrawal of the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

Correlation of echocardiographic and surgical findings in acute bacterial endocarditis.

From January 1979 to April 1983, 72 patients (pts) with bacterial endocarditis were treated. During their first stay in hospital 36 of them (age range: 23-67 years) underwent cardiac surgery because of severe congestive heart failure, unsuccessful antibiotic treatment of the infection and/or embolic events. In all these cases cardiac surgery was performed without preoperative catheterization. Surgery was recommended on the basis of clinical as well as M-mode and 2D echocardiographic findings. In 32 of the 36 pts the echocardiographic study completely predicted the surgical findings (23x the aortic valve, 1x the mitral valve, 1x the tricuspid valve, 5x the mitral and aortic valve, 1x the aortic valve and a VSD and 1x the triscuspid valve and a VSD were involved). The preoperative echocardiographic diagnosis was incomplete in 4 of the 36 pts. One aortic aneurysm, one aortic root abscess and 2x vegetations on the mitral valve were not detected by echocardiography. Surgery was recommended in these 4 pts because of additional aortic valve endocarditis proven by echocardiography. We conclude that combined M-mode and 2D echocardiography allows the accurate prediction of morphological alterations of the heart in the setting of acute bacterial endocarditis. Thus cardiac surgery can be recommended in pts with acute bacterial endocarditis without preoperative heart catheterization and coronary angiography.

Acute Disease↗
PubMed1984

Multiple anterograde and retrograde AV nodal pathways: demonstration by multiple discontinuities in the AV nodal conduction curves and echo time intervals.

Programmed electrical cardiac stimulation was performed in a 40-year-old man with documented recurrent, sustained ventricular tachycardia which was refractory to standard medical therapy. Both the presence of several discontinuities in the AV nodal conduction curves during atrial and ventricular stimulation and the time intervals of the AV nodal echo phenomena suggested the presence of multiple AV nodal pathways. The results of this study are of interest in further increasing our understanding of the electrophysiologic behavior of the human AV node.

Adult↗
PubMed1984

[Long-term drug treatment of chronic heart failure].

After reversible causes have been excluded and precipitating factors eliminated therapy of chronic heart failure is performed to achieve the following goals: A reduction of cardiac work by physical restriction; the increased risk of thromboembolic complications should be met by special physical exercises, elastic stockings and a low-dose heparin therapy in hospitalized patients. To improve the contractility of the heart muscle by digitalis. The efficacy of digitalis has been demonstrated by a double-blind study. It cannot be excluded, however, that digitalis therapy may be associated with an increased mortality in patients with coronary artery disease and complex ventricular arrhythmias. To eliminate symptoms of congestion. To reduce pre- and afterload by vasodilators. The application of vasodilators has become an established therapy in patients who do not respond to conventional therapy with digitalis and diuretics. By activation of the adrenergic nervous system and the renin-angiotensin system-an initially useful compensatory mechanism to sustain blood pressure and stroke volume-peripheral vascular resistance and end-diastolic volume increase in patients with chronic heart failure. Both factors contribute to an increase in afterload, thereby further diminishing left ventricular function. In this situation vasodilators are particularly effective. According to their main mode of action they alter venous capacity and/or systemic vascular resistance to a different degree. Knowledge of their effects is necessary for a successful application in individual patients.

Adrenergic beta-Antagonists↗
PubMed1983

Influence of verapamil therapy on left ventricular performance at rest and during exercise in hypertrophic cardiomyopathy.

To determine the hemodynamic effect of verapamil at rest and during exercise, 18 patients with hypertrophic cardiomyopathy were studied before and after 7 weeks of treatment with oral verapamil (maximal dose, 720 mg/day). At rest and at peak exercise, verapamil produced a significant increase in left ventricular (LV) systolic performance in terms of stroke volume index (rest, from 43 +/- 11 to 53 +/- 11 ml/m2, p less than 0.001; exercise, from 46 +/- 11 to 51 +/- 10 ml/m2, p less than 0.01), whereas heart rate decreased (rest, from 81 +/- 14 to 70 +/- 11 min-1, p less than 0.001; exercise, from 150 +/- 21 to 141 +/- 18 min-1, p less than 0.01). Cardiac index at rest and during exercise remained unchanged. Systolic vascular resistance did not change at rest, but decreased significantly during exercise (974 +/- 243 to 874 +/- 174 dynes s cm-5; p less than 0.05). After verapamil administration, pulmonary artery pressures did not change at rest, but decreased significantly during exercise. This was probably due to a shift in the LV pressure-volume relation. The improvement in LV hemodynamics was associated with a significant increase in exercise capacity. The findings of this study indicate that in patients with hypertrophic cardiomyopathy, hemodynamic improvement at rest and during exercise can be achieved by chronic administration of verapamil.

Adult↗
PubMed1983

[Value of echocardiography in the preoperative diagnosis of acute bacterial endocarditis].

Open-heart surgery was performed in 26 of 56 patients with acute bacterial endocarditis seen in three years. Non-controllable infection, cardiac failure or embolism were the indications for operation. In all instances pre-operative invasive angiographic diagnosis was dispensed with, indications being based entirely upon clinical findings plus the results of M-mode or cross-sectional echocardiography. In 22 of the 26 patients the pre-operative echocardiographic diagnosis coincided with the intra-operative one. In the other four patients the pre-operative echocardiographic findings were incomplete, but no surgically important information had been missed.

Adult↗
PubMed1983

Haemodynamic and cardiac metabolic effects of the new beta 1 agonist prenalterol in patients with cardiac failure.

Prenalterol, a beta 1 selective agonist, exerts a positive inotropic action in animal studies as well as in human volunteers and is effective when administered orally. To assess its immediate haemodynamic and myocardial metabolic effects, we studied the response to prenalterol (50 and 100 micrograms kg-1 given intravenously by cardiac catheterization) in 15 patients with congestive heart failure secondary to coronary artery disease or non-ischaemic cardiomyopathy. At peak effect, cardiac index increased from 2.6 +/- 0.5 to 3.2 +/- 0.8 l min-1 m2 (mean +/- S.D.) (P less than 0.001); peak rate of left ventricular pressure development rose from 963 +/- 242 to 1335 +/- 411 mmHg s-1 (P less than 0.001); left ventricular end-diastolic pressure fell from 25 +/- 6 to 17 +/- 7 mgHg (P less than 0.001); coronary sinus blood flow increased from 113 +/- 39 to 148 +/- 55 ml min-1 (P less than 0.01); myocardial oxygen consumption was augmented from 12.7 +/- 3.9 to 16.4 +/- 5.8 ml min-1 (P less than 0.001); and heart rate increased slightly (from 76 +/- 12 to 86 +/- 14 beats min-1; (P less than 0.05)). No significant changes occurred in left ventricular systolic pressure, stroke volume index, myocardial lactate extraction rate and myocardial arteriovenous oxygen difference, and no patients developed angina, ECG changes or ventricular arrhythmias. Infusion of prenalterol effectively improved haemodynamic function and cardiac metabolism in cardiomyopathy. Therefore this agent deserves further investigation to evaluate its possible role for the long-term therapy of patients with chronic heart failure.

Adrenergic beta-Agonists↗
PubMed1983

[Electrophysiologic determination of 3 intranodal pathways using various time intervals].

Programmed electrical stimulation of the heart was performed in a 40-year-old man with documented recurrent, sustained ventricular tachycardia, which had proved refractory to standard medical therapy. In this patient, both the presence of several discontinuities in the atrioventricular (AV-)nodal conduction curves during atrial and ventricular stimulation and the varying time intervals of the AV-nodal echo phenomena suggested the presence of multiple AV-nodal pathways.

Adult↗