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Biomedical subjects

F Burkart

Publications and source records attributed to F Burkart.

At least 91 records · Page 5Linked to original sources
PubMed1986

[Secretion of atrial natriuretic peptide: relation to atrial pressure and systemic blood pressure].

To determine the influence of atrial pressure, heart rate and loss of atrial-ventricular synchrony in the release of atrial natriuretic peptide (ANP), plasma ANP concentrations were measured by radio-receptor assay in 12 patients during diagnostic cardiac catheterization and in patients with atrial fibrillation and during cardiac pacing. There was a relationship between right atrial pressure and right atrial ANP concentration (r = 0.813, p less than 0.01). Acute loss of atrial-ventricular pacing mode induced an increase in plasma ANP concentration from 44 +/- 8 to 104 +/- 13 pmol/l (n = 11, p less than 0.01) provided that systemic blood pressure was maintained. In contrast, if hypotension developed during ventricular pacing, the ANP levels fell from 68 +/- 11 to 14 +/- 7 pmol/l (n = 5, p less than 0.05) within five minutes despite elevation of atrial pressure. We therefore conclude that atrial pressure and the loss of atrioventricular synchrony may profoundly alter ANP release. The fall in plasma ANP concentration in acute hypotension suggests that, in addition to atrial pressure, ANP release is controlled by a peripheral negative feedback mechanism.

Aged↗
PubMed1986

[Indications and new developments in pacemaker therapy].

In the course of the past 25 years the indication for pacemaker implantation has changed from AV-block to the sick sinus syndrome in about 40% of patients. In the same period pacemaker technology has developed considerably and today there are, in addition to the ventricular inhibited pacemaker, two-chamber systems (essentially DDD pacemakers) and pacemakers with an increasing pulse rate during physical effort. The new nomenclature, mode of action and hemodynamic implications of the various systems are explained, and recommendations for implantation are given.

Electric Power Supplies↗
PubMed1986

[Physical performance with rate-responsive pacemakers].

The effects of the new rate-responsive pacemaker Medtronic Activitrax on maximal exercise heart rate and physical work capacity were studied acutely and after two weeks in 10 patients. Compared to the VVI-mode, heart rate increased in activity mode during exercise from 102.1 +/- 29.0 to 115.8 +/- 13.5/min (p less than 0.05). Similarly, physical work capacity increased from 343 +/- 260 to 528 +/- 354 watts X min (p less than 0.02). This effect persisted over 2 weeks. Thus, using rate-responsive pacing a significant improvement in working capacity could be shown in patients with inadequate exercise heart rate.

Aged↗
PubMed1986

[Swiss pacemaker statistics, 1985].

In the annual pacemaker survey covering all 34 centres implanting cardiac pacemakers in Switzerland the data have been collected in more detail in the last two years and are presented more extensively. The number of first implants (1146, or 225 per million population) has remained constant with slight variation over the last 3 years. Dysfunction of the sinus node as an indication decreased to 31%. The use of programmable pacemakers further increased, leaving only 6% non-programmable. Physiological pacemaker-systems were used slightly less frequently but not in the larger pacemaker centers. The rate of intervention for lead problems remained unchanged at 1.1% of the total pacemaker population.

Humans↗
PubMed1986

Atrial natriuretic peptide and atrial pressure in patients with congestive heart failure.

To define the relation between atrial pressures and the release of atrial natriuretic peptide, we measured plasma concentrations of the peptide in 26 patients with cardiac disease--11 with normal atrial pressures and 15 with elevated atrial pressures (11 of these 15 had elevated pressures in both atria). Mean peptide levels (+/- SEM) in the peripheral venous blood were increased in the 11 patients with cardiac disease and normal atrial pressures, as compared with 60 healthy controls (48 +/- 14 vs. 17 +/- 2 pmol per liter). In the patients with elevated atrial pressures, peptide concentrations were increased twofold in peripheral venous, right atrial, pulmonary arterial, and systemic arterial plasma, as compared with the concentrations in the patients with normal atrial pressures. A step-up in peptide concentration was seen between the venous and right atrial plasma (P less than 0.002) and between the pulmonary and systemic arterial plasma (P less than 0.01), suggesting release of the peptide from the atria. A linear relation was found between right atrial pressure and right atrial peptide concentration (r = 0.835, P less than 0.001) and between pulmonary wedge pressure and the systemic arterial peptide concentration (r = 0.866, P less than 0.001). Right atrial pressure and the peptide concentration both increased with exercise testing in the nine patients evaluated. We conclude that the release of atrial natriuretic peptide is at least partly regulated by right and left atrial pressures. Distinguishing the relative contributions of the two atria and defining the role of peptide release in the pathogenesis of heart failure will require further investigation.

Adult↗
PubMed1986

Prognostic significance of right ventricular ejection fraction for persistent complex ventricular arrhythmias and/or sudden cardiac death after first myocardial infarction: relation to infarct location, size and left ventricular function.

To assess the prognostic significance of right ventricular dysfunction after a first myocardial infarction for complex ventricular arrhythmias and or sudden cardiac death in relation to infarct location, size and left ventricular function, a series of 127 consecutive patients was prospectively studied and followed up for one year. Prior to hospital discharge, a 24-hour electrocardiographic recording and radionuclide angiocardiography were performed. Right ventricular ejection fraction was related to inferior infarct location and size (r = 0.45, P less than 0.01): similarly left ventricular ejection fraction was related to anterior infarct location and size (r = 0.76, P less than 0.001). The incidence of severe ventricular arrhythmias was significantly higher in patients with isolated right or left ventricular dysfunction compared to patients with normal function; it was highest in patients with severe depression of both ventricles. Patients with complex ventricular arrhythmia and/or sudden cardiac death had significantly reduced left and right ventricular ejection fractions. Detailed analysis in patients with left ventricular ejection fraction greater than 0.40 vs. less than or equal to 0.40 showed that presence of complex ventricular ectopic activity and/or sudden cardiac death after myocardial infarction was related not only to left, but also independently to right ventricular dysfunction. These results imply a significant prognostic contribution of right ventricular dysfunction to the occurrence of severe ventricular arrhythmias and/or sudden cardiac death after myocardial infarction independent of and additive to left ventricular dysfunction.

Adult↗
PubMed1986

Effects of bisoprolol in relation to metoprolol and bufuralol on left ventricular hemodynamics at rest and during exercise in chronic ischemic heart disease.

To assess acute hemodynamic effects of bisoprolol on left ventricular hemodynamics at rest and during exercise, 16 patients with documented chronic ischemic heart disease were studied and compared with patients after administration of metoprolol and bufuralol. Simultaneous right heart catheterization and radionuclide angiocardiography were performed at rest and during exercise before and after drug administration. Bisoprolol was given orally to 16 patients, six receiving 5 mg, and 10 patients receiving 20 mg. Metoprolol was injected intravenously in a dose of 0.15 mg/kg to another 16 patients, and 30 mg bufuralol were given orally to 10 patients. The hemodynamic profiles of all three compounds were similar to that previously described after acute beta-blockade. All three drugs tested and compared showed a marked negative chronotropic effect, while there were slight differences in the negative inotropic and blood pressure lowering effect. Bisoprolol induced only mild negative inotropic changes, which were barely detectable after the 5 mg dose. The negative inotropic changes were more pronounced after metoprolol, and were partly balanced by the vasodilating properties of bufuralol. Thus, bisoprolol showed a significantly reduced rate pressure product with only a relatively mild negative inotropic effect. Based on these observations, even the higher dose of 20 mg bisoprolol seems to be hemodynamically safe for clinical application.

Adrenergic beta-Antagonists↗
PubMed1986

Non-invasive grading of aortic regurgitation by Doppler ultrasonography.

Doppler ultrasound without concomitant echocardiographic imaging was used to grade isolated aortic regurgitation in 21 patients. The severity of aortic regurgitation was subsequently graded (from 0 to IV) angiographically. A 2 MHz continuous wave Doppler transducer was placed over the apex of the heart and the beam was aimed parallel to the mitral flow by means of acoustic guidance. Mitral pressure half time was calculated from the analogue maximum velocity tracing and it was less than or equal to 60 ms in 10 controls; 50-120 ms in five patients with grade II, 120-160 ms in nine patients with grade III, and greater than or equal to 160 ms in seven patients with grade IV aortic regurgitation. These results indicate that a semi-quantitative grading of aortic regurgitation may be obtained non-invasively with non-imaging Doppler ultrasonography in patients without concomitant mitral valve disease.

Adult↗
PubMed1985

[Relation between intraoperative blood flow measurements and graft patency afer aortocoronary bypass surgery].

During aorto-coronary bypass surgery, electromagnetic flow measurements of venous grafts were performed in 50 consecutive patients at rest and after stimulation with papaverine (2 mg) to assess whether early postoperative patency was predictable. The overall patency rate at day 9-11 was 95.4% (145/152 distal grafts; 118 proximal grafts). Flow in all bypass grafts averaged 52.5 +/- 31.4 ml/min and increased after papaverine stimulation by 46.9 +/- 32.2 ml/min (p less than 0.01). 5 of 6 grafts with a flow of less than 30 ml/min and without adequate flow increase after papaverine (less than 80%) were occluded. Grafts with a flow of greater than or equal to 30 ml/min or an increase of greater than or equal to 80% after papaverine, had a high short-time patency rate (98%). Thus, perioperative flow measurements combined with papaverine stimulation predicted early patency of single grafts with an accuracy of 95%.

Coronary Artery Bypass↗
PubMed1985

[Reevaluation of pacemaker-induced reentry tachycardias: incidence, mechanisms and therapy].

To reassess incidence, mechanisms and therapeutic possibilities in the treatment of pacemaker-induced reentry tachycardias (RT) in patients with the second generation of DDD-pacemakers, 35 consecutive patients were studied prospectively by measuring VA conduction at implant and searching for RT clinically and by repeat 24-hour ECG monitoring. Reprogramming to the VVI mode because of atrial flutter and to the AAI mode because of lead displacement was necessary in 2 and 1 of the patients respectively. RT were detected in 7/32 patients (22%), 4 of whom were symptomatic. The triggering mechanism of RT was premature ventricular contraction in 4 patients, premature atrial contractions in 1, loss of atrial sensing in 1, and remained unclear in 1. Unlike the 30% of patients of an earlier consecutive series with first generation of physiologic PM who had RT and required permanent reprogramming to VVI stimulation in 10% of cases, RT was abolished in all patients maintaining physiologic pacing by prolonging the atrial refractory period, shortening the av delay, adjusting atrial output or atrial sensing, or by antiarrhythmic therapy.

Aged↗
PubMed1985

[Swiss pacemaker statistics for 1984].

In a study of Swiss pacemaker statistics for 1984, all 34 centres implanting cardiac pacemakers in Switzerland were covered. The number of first implants slightly decreased (218 per million population compared with 230 in 1983). There are some 7500 pacemaker patients in Switzerland, most of the pacemakers being multiprogrammable or programmable. The percentage of physiological systems increased to 10% and in some centres up to 35%. Reintervention for lead problems was necessary in 1.2% of the total pacemaker population.

Humans↗
PubMed1985

[Risk profile and prognosis after myocardial infarct complicated by ventricular fibrillation].

In a prospective series of 190 patients under the age of 70 with a first myocardial infarction, the risk profile for ischemia, heart function and arrhythmias was investigated at the time of hospital discharge. Fifteen of these 190 patients had had ventricular fibrillation within 24 hours after admission which could be converted into sinus rhythm. In comparison, patients with ventricular fibrillation had a significantly larger infarct as estimated with the thallium-defect score (11.0 +/- 5.8 vs. 7.3 +/- 5.4; p less than 0.02)). In addition, left ventricular ejection fraction at rest was lower, at 42.7 +/- 17.4% compared to 50.0 +/- 14.0, but the p-value reached only 0.07. Persistent arrhythmias and ischemia were not significantly different in the two groups. In the first year after infarction none of these 15 patients died, compared to 8/175 patients.

Adult↗
PubMed1985

[Cadmium studies on the effect of environment, soil and variety on tobacco and cadmium transfer into cigarette smoke].

The results as outlined in this paper are based on a 10-year-investigation by the Tobacco Research Institute, Forchheim. Emissions into the environment may lead to higher Cd-content of tobacco and other crops. Geological soil conditions may influence the soil/plant--Cd-transfer. Genetically dependent variety differences in Cd-uptake can be found in field as well as in greenhouse experiments. A comparison between domestic and foreign leaf tobaccos showed Cd-levels at the same order of magnitude. Analyses of German cigarette brands (with and without filter) demonstrated that 0.05 micrograms Cd/cigarette are transferred from cigarette tobacco into the mainstream smoke, corresponding to a mean transfer rate of 5.1%.

Cadmium↗
PubMed1985

Important differences between short- and long-term hemodynamic effects of amiodarone in patients with chronic ischemic heart disease at rest and during ischemia-induced left ventricular dysfunction.

To assess and compare the hemodynamic profile of short-and long-term amiodarone administration in the same set of patients and to investigate hemodynamic mechanisms responsible for the antianginal effect of this drug, 10 patients with documented coronary artery disease and stable angina pectoris were studied. Simultaneous right heart catheterization and equilibrium radionuclide angiocardiography were performed at rest and during exercise before therapy (control), after a 5 minute intravenous infusion of 7.5 mg/kg of amiodarone and after 21.0 +/- 4.3 days of peroral therapy (10 days 800 mg/day, 7 days 400 mg/day and then 200 mg/day). After acute drug administration, ejection fraction, stroke index and systolic blood pressure decreased, whereas heart rate, left and right ventricular filling pressures and systemic vascular resistance increased. These effects were reversed after long-term therapy; all measured values returned to control levels except for heart rate, which decreased below the control value, and right atrial pressure, which remained slightly elevated. Amiodarone drug levels decreased from 4.8 +/- 1.8 after intravenous infusion to 1.2 +/- 0.6 mg/liter after long-term therapy. After adjustment for hemodynamic changes at rest, there were still significant reductions in heart rate, mean arterial pressure and rate-pressure product during exercise. It is concluded that the marked negative inotropic effect of amiodarone administered acutely in the dose applied calls for cautious use of this drug when administered intravenously. In contrast, long-term oral amiodarone therapy seems hemodynamically safe, even in patients with moderately depressed left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1985

Coronary artery bypass grafts. Influence of preoperative risk factors on the late postoperative course.

In order to assess the influence of preoperative risk factors on the late postoperative course, 186 consecutive patients in whom coronary artery bypass graft (CABG) was performed for chronic stable angina (169 men, 17 women, mean age +/- SD 54 +/- 8 years) were followed for an average of 54 (6 to 113) months. The overall five-year survival rate by life-table analysis was 90 +/- 2 percent. The postoperative course was considered favorable in 112 patients (60 percent) in whom angina was absent or improved by at least 2 NYHA classes throughout the entire follow-up, and was unsatisfactory in 74 patients. It was concluded that the late postoperative course of patients with CABG was unfavorably influenced by the presence of two or three risk factors, and a high preoperative cholesterol level was the only single risk factor associated with unsatisfactory outcome.

Adult↗
PubMed1985

Effect of short and long term administration of amiodarone on ischaemia-induced left ventricular dysfunction. Implications for combined antianginal drug therapy.

To asses haemodynamic effects of short and long term amiodarone on ischaemia-induced left ventricular dysfunction and to compare them with those of glyceryl trinitrate (nitroglycerin), beta-blocking and calcium antagonist drugs, 19 patients with chronic ischaemic heart disease were studied. All patients underwent simultaneous right heart catheterisation and equilibrium radionuclide angiocardiography at rest and during symptom-limited supine bicycle exercise. After control measurements without antianginal therapy, 10 patients received 7.5 mg/kg amiodarone intravenously over 5 minutes (short term study) followed by oral administration of amiodarone for 3 weeks (long term study). The remaining 9 patients were studied following the randomised administration of glyceryl trinitrate (0.8 mg sublingually), metoprolol (0.15 mg/kg intravenously) and nifedipine (5 ng/kg/min). During exercise known to provoke angina pectoris without therapy (control study), amiodarone improved myocardial oxygen consumption by reducing heart rate and systolic blood pressure without the negative inotropic effects seen after acute beta-adrenoceptor blockade. Comparisons with the haemodynamic profiles of other antianginal drugs suggest that amiodarone may be most effective when combined with glyceryl trinitrate or nifedipine for the treatment of ischaemic left ventricular dysfunction.

Adult↗