Search PubMed⌕ Search

Biomedical subjects

C Weinhold

Publications and source records attributed to C Weinhold.

52 records · Page 3Linked to original sources
PubMed1986

What is the most appropriate stimulation mode in patients with sinus node dysfunction?

Sinus node disease (SND) has caused many controversies about the appropriate stimulation mode. We compared the advantages and disadvantages of VVI, AAI, DDD, and DDI mode. In an additional study, left ventricular function at rest (R) and during exercise (E) was investigated in dual chamber and ventricular stimulation mode with a stimulation rate of 70 ppm (R) and 110 ppm (E). A total of 223 patients (pts) was investigated (67 AAI, 87 VVI, 69 DDI). Hemodynamic disadvantages in VVI mode resulted in a 55% actuarial incidence of atrial fibrillation after five years. In AAI mode, we found another 25% complication rate due to impaired AV conduction (n = 9) or a bradyarrhythmia (n = 6) with slow ventricular response. DDI mode implies the possibility of sustaining a pacemaker mediated tachycardia. Single ventricular stimulation with a high stimulation rate (110 ppm) under E showed a worse left ventricular performance as compared to dual chamber stimulation. DDI mode shows none of the aforementioned disadvantages. To sum it up: Until a dual chamber rate responsive pacemaker becomes available, the DDI mode represents the best stimulation mode for patients with a SND.

Atrial Fibrillation↗
PubMed1985

[Hemodynamic changes following heparin injection in aortocoronary bypass operations. Sequela of histamine liberation].

Prior to cannulation for extracorporeal circulation, 375 Units of Heparin/kg body weight were applied to 22 patients (group 1) into the right atrium. A few minutes later, characteristic changes in haemodynamics were observed. In a second group of 10 patients, the same amount of heparin was injected directly into the ascending aorta to avoid the passage of an undiluted bolus of heparin through the pulmonary vessels. In this group, the haemodynamic effects of heparin seemed to be slightly weakened. Immediately after administration of heparin, a significant increase of plasma histamine was measured (in 12 patients of group 1). This might be the main reason for the heparin-dependent haemodynamic effects.

Blood Pressure↗
PubMed1985

[Age-dependent regulation of cardiac glycoside receptors].

Specific binding of cardiac glycosides to their receptors precedes their actions on the myocardium. Thus changes in the number and affinity of these membrane bound receptors will vary the response to cardiac glycoside therapy and the incidence of side-effects. Several studies have reported an age-dependent decrease in the number of cardiac glycoside receptors in animals as well as in human erythrocytes. These results may explain the increase in cardiac glycoside sensitivity with age which is not accounted for by the reduction in kidney function. Furthermore, changes in both binding affinity and capacity are known to occur in several diseases which are more common in older patients. Therefore, we have measured the number and affinity of cardiac glycoside receptors in atrial samples from 209 patients and in papillary muscle samples from 59 patients taken during coronary bypass graft surgery or mitral valve replacement. Further, the maximal increase in force of contraction was measured using papillary muscle strips from some of these patients. Our results show no significant age-dependent alteration in the characteristics of the cardiac glycoside receptors but a reduced myocardial receptor density in males (3.47 +/- 0.14 X 10(14)/g protein) compared with females (4.44 +/- 0.21 X 10(14)/g protein) (p less than 0.001) which is more pronounced in older patients. About 30% fewer cardiac receptors either per g protein or per g wet weight are present in patients with coronary heart disease or dilative cardiomyopathy. The maximal inotropic effect of ouabain in human papillary muscle strips is correlated with the number of cardiac glycoside receptors present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

[Reoperation following aortocoronary bypass. Indications and results].

Aorto coronary reoperation can be performed with a low morbidity and mortality rate which approaches that of initial surgical procedures. Increasing experience in setting indication and in managing surgical procedures has led to better results during the last years. There is a good prognosis in such cases having only singular new stenoses in greater coronary vessels, which still have a good run off. Also good results can be expected in patients suffering from stenotic or completely occluded grafts, without progression of disease. Only 50-60% of the reoperated patients obtain complete relief of angina, which is comparable to our results of 41 cases.

Angina Pectoris↗
PubMed1984

Innominate artery compression of the trachea in infancy and childhood: is surgical therapy justified?

We reviewed innominate artery compression of the trachea in 10 medically treated patients (group I) and 6 children who underwent innominate arteriopexy (group II). The symptoms were as follows: (1) stridor (80% in group I, and 66% in group II), (2) recurrent bronchopulmonary infections (40% in group I, 66% in group II) and (3) apneic attacks (10% in group I and 100% in group II). Diagnosis was made in all cases by tracheobronchoscopy . It revealed severe tracheal stenosis (narrowing more than 2 thirds) in all children treated by surgery. In group I the tracheal stenosis was mild (narrowing less than one third) in 5 cases, moderate (narrowing from one third to 2 thirds) in 4 cases and severe in only one case. The indication for surgery was based on a history of apneic attacks. In this study innominate arteriopexy has proven to be a reliable and low risk procedure which relieved reflex apnea and recurrent bronchopulmonary infections in all 6 children operated upon.

Apnea↗
PubMed1983

[Heart surgery].

Explore the source record for details and available documents.

Bioprosthesis↗
PubMed1983

Organization and structure of branches in the rat pulmonary arterial bed.

Pulmonary arteries were fixed by perfusion under constant pressure and filled with rubber. The hardened rubber cast delineated the arterial bed, permitting dissection of axial vessels and all branches. Each segment was prepared for scanning electron microscopy and transmission electron microscopy. Branches arising at acute angles from the axial artery and the first two generations of its branches, regardless of diameter, had the same concentric muscle layer structure as parent vessels. Endothelial cells of the parent vessel were oriented into the ostia of these branches. Branches that came off the axial vessel or its branches at right angles had spiral muscle bundles and led to nonmuscular precapillary vessels. Right angle branches also had similar wall structure regardless of diameter. Near the ostia of right angle branches, endothelial cells of the parent vessels did not show orientation of their long axis into the branch lumens. It was concluded that branch arteries arising at acute angles are conduit which carry blood to distant parts of the lung while right angle branches are a histologically different group which distribute the blood to local capillary beds.

Animals↗
PubMed1977

[Correction of tetralogy of Fallot and its influence to oxygen transport and lung changes. Part I. Oxygen transport (author's transl)].

30 patients with tetralogy of Fallot were examined before and after correction. 10 of whom had previous procedures including 13 Blalock-Taussig shunts, 1 Cooley anastomosis and 6 pulmonary valvulotomies (Brock) with a dilator. Hemoglobin and blood gases were measured in 22 patients pre- and postoperatively on the 7th respectively 14th day and finally after 12 months. In 8 children the concentration of 2,3-DPG was accessed (pre-, postoperatively, immediately in ICU, on the 1st, 7th, 14th day and after 21 months). Hypoxia of various degrees was found at any time of the investigation, verified by a low venous oxygen saturation, high 2,3-DPG concentration and an erythrocytosis. The 2,3-DPG concentration was always elevated (preoperatively 18.2 +/- 1.8 muMol/g Hb; postoperatively 1st till 14th day 19.0 +/- 2.2; after 21 months 16.3 +/- 1.2 muMol/g Hb). Preoperatively hypoxia was correlated to the degree of the heart disease expressed by the hight of the Hb-concentration. In contrary after the correction signs of hypoxia (decreased venous oxygen saturation, increased 2,3 DPG-concentration) appeared with a low Hb as found in patients with anemia. The long term check-ups are indicative for slight cardiac residual disorders as there are hypoxic myocardial damage, residual gradients over the right ventricular outlet, reopened VSD's, and ventriculotomy scar tissue. Though the elevated 2,3-DPG-concentration and the consecutive rightward shift of the oxygen saturation curve obviously compensate these cardiac handi-caps as the excellent physical condition of the children shows.

Adolescent↗
PubMed1977

[Correction of tetralogy of Fallot and its influence to oxygen transport and lung changes. Part II: Lung changes (author's transl)].

22 children got lung scans 3 weeks respectively 12 months after the correction of a tetralogy of Fallot. In 18 cases previous operations were done: 12 times a Blalock-Taussig shunt and 6 times a Brock procedure. For the scan 20-70 mu diameter albumin macrospheres were used, which were labeled with Technetium 99m. The following pathologicla lung changes were seen: 1. Loss of perfusion, typical after Blalock-Taussig shunt procedure; these findings were always on the left side, the site of the anastomosis. 2. Anomalous flow distrubution (=more spheres in the upper than in the lower lobe) in the left lung; these changes were also caused by the Blalock-Taussing shunts, but disappeared within the one year follow-up after the correction. 3. Intrapulmonary rigt-left shunts (according to the dilatation of the alveolar capillaries). These decreased within one year from 9.9+/-1.3 to 4.6+/-0.9%.

Adolescent↗
PubMedDate not supplied

Effects of preservative-free heparin on plasma histamine concentration and on hemodynamics in patients undergoing aortocoronary bypass surgery.

Several reports, dealing with typical cardiovascular reactions immediately after injection of heparin during cardiac surgery, have been presented. A possible reason for these reactions is a short-lasting elevation of plasma histamine concentration following heparin injection. As most types of heparin contain antibacterial preservatives such as benzyl alcohol, which can cause adverse reactions, both substances, heparin itself and the preservative, can theoretically be responsible for this reaction. Therefore, this study was carried out in order to measure the effects of preservative-free heparin on plasma-histamine levels and on hemodynamic parameters. It became evident that preservative-free heparin also entails characteristical hemodynamic effects, such as a decrease in arterial mean pressure and peripheral vascular resistance as well as an increase in cardiac output. A significant increase in plasma-histamine concentration could be shown 20-120 seconds after injection of heparin. We conclude that benzyl alcohol is not the major reason for the hemodynamic effects and elevation of plasma-histamine concentration, following heparin injection, but we cannot exclude that benzyl alcohol does in fact play a minor role. The results of this study suggest that the cardiovascular reactions and the elevation of plasma histamine concentration following heparin injection are heparin-specific phenomena.

Benzyl Alcohol↗
PubMedDate not supplied

Experimental studies of the anatomical and functional characteristics of kangaroo aortic valve bioprostheses.

In many tests done in vitro and in vivo on porcine aortic valve grafts, high pressure gradients were found under normal as well as under stress conditions. The transvalvular pressure difference is due to the immobility of the right aortic porcine leaflet that is fixed tightly to the muscular septum of the ventricle. Our own studies of 24 kangaroo hearts show different anatomical features: the right leaflet is practically free in this movement. Thus the maximum orifice area of the kangaroo aortic valve is reduced by only 24.2 per cent, whereas the porcine valve shows a reduction of 36.5 per cent. This difference proved to be highly significant (P less than 0.001). Therefore, in cooperation with Hancock Laboratories, kangaroo aortic valve grafts were tested as xenotransplants, using a pulse duplicator. The first results show that larger orifice areas are achieved by kangaroo valves one or two sizes smaller than their porcine counterparts.

Animals↗
PubMedDate not supplied

Registration of thoracic electrical bioimpedance for early diagnosis of rejection after heart transplantation.

In this study, registration of thoracic electrical bioimpedance was used for early detection of acute rejection after heart transplantation. Thirty-five heart transplant recipients were monitored by registration of thoracic electrical bioimpedance signals during the immediate postoperative period and during the outpatient follow-up. At the same time, endomyocardial biopsy specimens were taken. In addition to cardiac stroke volume index and ejection fraction, the acceleration index (seconds -2) was calculated. This acceleration index describes the acceleration of blood volume and represents a function parameter of the myocardial inotropy. Seventeen acute rejection episodes were diagnosed during the follow-up period. The average acceleration index value during the 17 rejection episodes was 92.5 +/- 11.7 sec-2 and thus significantly lower when compared with the nonrejection levels (p < 0.05). The acceleration index values decreased during acute rejections by an average of 36.4 +/- 19.3 sec-2 (28%). The sensitivity of this diagnostic parameter in the examined patients was 71%, and the specificity was 100%. Thus registration of thoracic electrical bioimpedance and calculation of the acceleration index represents a quick and noninvasive monitoring technique and can ideally be used in the outpatient clinic as a supplement to invasive endomyocardial biopsies.

Adult↗