Biomedical subjects

Gunter Hempelmann

Publications and source records attributed to Gunter Hempelmann.

58 records · Page 4Linked to original sources

PubMed1992

RETRACTED: Age and right ventricular function during cardiac surgery.

Elderly patients undergoing cardiac surgery are reported to be at a higher risk for circulatory failure than younger patients, most likely because of ventricular decompensation. To assess the role of the right heart in these patients, right ventricular (RV) hemodynamics in 40 consecutive elderly patients (greater than 70 years; mean = 77.1 +/- 3.4 years) were compared with 40 consecutive younger patients (50 to 60 years; mean = 55.2 +/- 3.0 years) undergoing elective coronary artery bypass surgery. In addition to standard hemodynamic variables, RV ejection fraction (RVEF) and RV end-systolic and end-diastolic volumes (RVESV, RVEDV) were studied perioperatively using a thermodilution technique. None of the elderly patients died in the perioperative period. The course of RV function was comparable in both groups during the entire investigation period, but the absolute values of RVEF before the onset of cardiopulmonary bypass (CPB) were significantly higher in the younger patients (48.0 +/- 4.4%) than in the older patients (38.9 +/- 4.6%). RVEDV and RVESV were always higher in the older patients in the pre-bypass period than in the control group. None of the other hemodynamic parameters showed significant differences between the groups. Analysis of covariance showed no correlation between RV volume and pressure parameters. Inotropic support during and after termination of CPB was necessary more often in the older (epinephrine, 6.7 +/- 2.0 micrograms/min) than in the younger patients (epinephrine, 4.4 +/- 2.2 micrograms/min). It is concluded that older patients undergoing myocardial revascularization can have excellent results. However, they may be predisposed to right heart complications because of their reduced RV function.

Aged↗

PubMed1992

RETRACTED: Right ventricular function in patients with aortic stenosis undergoing aortic valve replacement.

The effects of aortic stenosis (AS) on right ventricular function during cardiac surgery are not fully understood. Forty patients undergoing aortic valve replacement with either a systolic transvalvular gradient of less than 100 mm Hg (82.1 +/- 5.5 mm Hg; group 1, n = 20) or greater than 120 mm Hg (131.1 +/- 6.9 mm Hg, group 2, n = 20) were investigated with regard to right ventricular function in the perioperative period. Right ventricular ejection fraction (RVEF), right ventricular end-systolic volume (RVESV), and right ventricular end-diastolic volume (RVEDV) were measured by means of the thermodilution technique. Before cardiopulmonary bypass (CPB), RVEF was significantly lower in group 2 patients (34% +/- 6%) than in group 1 (45% +/- 5%). After CPB, RVEF increased significantly in group 2 (28% +/- 4% to 49% +/- 5%), and no further differences were noted between the groups. In the patients with a higher systolic transvalvular gradient, RVEDV and RVESV were lower at the start of surgery, but increased after opening the pericardium. Cardiac index was also lower in these patients. Pericardiotomy resulted in a decrease in right ventricular end-systolic pressure (RVESP) only in the patients of group 2. In these patients more epinephrine was necessary to maintain stable hemodynamics during the post-bypass period. It is concluded that patients with AS are at risk of reduced right ventricular function when the systolic transvalvular pressure gradient is more than 120 mmHg. Knowledge of the complex interaction between the two sides of the heart may enable anesthesiologists to optimize management during the perioperative period.

Aged↗

PubMed1991

RETRACTED: Acute preoperative hemodilution in cardiac surgery: volume replacement with a hypertonic saline-hydroxyethyl starch solution.

Preoperative hemodilution (HD) is a recommended practice in cardiac surgery that conserves blood and reduces the complications of homologous blood transfusion. In 45 patients undergoing myocardial revascularization, HD was performed preoperatively. Withdrawn volume (10 mL/kg) was replaced either by a new hypertonic saline (HS) solution prepared in hydroxyethyl starch (HES) (2,400 mOsm/L, HS-HES group, n = 15) or by a standard low molecular weight hydroxyethyl starch solution (6% HES 200/0.5, HES group, n = 15) to maintain baseline PCWP (acute normovolemic hemodilution [ANH]). Fifteen comparable patients without HD served as controls. Significantly less HS-HES (210 +/- 20 mL) than HES 6% (890 +/- 90 mL) was necessary to sustain hemodynamics during HD. Stable cardiocirculatory conditions were obtained even after termination of bypass. Fluid balance during cardiopulmonary bypass as well as in the postoperative period was significantly lower in HS-HES-treated patients. With regard to hemodynamics, CI increased most in the HS-HES group (+36%), whereas systemic vascular resistance was lower in these patients. Right ventricular ejection fraction increased only in HS-HES patients (+15%). However, sodium concentration as well as osmolarity increased after volume replacement with HS-HES, without exceeding normal values. None of the patients suffered from organ failure. Pulmonary gas exchange (PaO2) was less compromised in the HS-HES patients. There were no renal function differences between the groups. In conclusion, HS solution prepared in HES is an attractive alternative for blood substitution in cardiac patients undergoing acute hemodilution for blood conservation.

Atrial Function, Right↗

PubMedDate not supplied

Localization of putative neurotransmitters in the mantle and siphuncle of the mollusc Nautilus pompilius L. (Cephalopoda).

The neurotransmitter supply in the nerve endings of the mantle and the siphuncle, i.e. in organs that are responsible for the shell formation in the ectocholeate Nautilus pompilius, were investigated with electron microscopical, fluorescence-, immuno- and enzyme histochemical methods as well as with high pressure liquid chromatography (HPLC). Using antibodies against serotonin and the tetrapeptide FMRF-amide, positive reactions were demonstrated immunohistochemically within the terminal nerve fibres of the mantle and the vessels of the siphuncle. Enzyme histochemical proof of the presence of specific acetylcholinesterase yielded positive results in the muscle fibres of the mantle and siphuncle. Additionally, in the mantle, glyoxylic acid-induced fluorescence was shown within the nerve endings indicating catecholamines as neurotransmitters, whereas in the siphuncle such fluorescence did not appear. However, the HPLC-analyses showed that in the mantle and also in the siphuncle the content of dopamine is higher than that of noradrenaline whereas only traces of adrenaline occur in both organs suggesting dopamine as a putative neurotransmitter. Transmission electron microscopical examination of the nerve endings of both organs revealed that different types of vesicles were distinguished that could be considered as cholinergic, aminergic and peptidergic structures.

Acetylcholinesterase↗