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Biomedical subjects

R Lange

Publications and source records attributed to R Lange.

448 records · Page 25Linked to original sources
PubMedDate not supplied

Effects of recurrent ischemia on myocardial high energy phosphate content in canine hearts.

Successive ischemic episodes are commonly seen in clinical and experimental cardiology. Although prolonged abnormalities of the canine myocardium have been described following a single ischemic episode, it is not known whether myocardial injury is cumulative following multiple ischemic episodes. Dogs were subjected to three 15-min left anterior descending coronary artery occlusions, each followed by 30 min of reperfusion. In vivo biopsies were obtained for biochemical analysis before and during the first occlusion and 30 min into each reperfusion period. ATP and creatine phosphate (CP) fell in the endocardium during occlusion by 24% and by 69% respectively (both p less than .0001). While CP recovered during each reperfusion period, ATP remained significantly depressed. Loss of membrane-permeable purine nucleotide synthesis precursors occurred with the first reperfusion period but not with the second and third reperfusion periods. Therefore, reperfusion following one 15-min coronary occlusion is associated with severe depression of myocardial high energy phosphates; however, two additional occlusions do not cause a further decrease of these substances when intermittent reperfusion is allowed for 30 min.

Adenine Nucleotides↗
PubMedDate not supplied

Quantification of periprosthetic valve leakage with multiple regurgitation jets by magnetic resonance imaging.

A patient with aortic prosthetic valve endocarditis required replacement of the prosthesis, After initial recovery, his left ventricular function gradually declined and echocardiography revealed minor paravalvular leakage and a cavern around the prosthesis. Magnetic resonance imaging was performed, flow-imaging and volume-based measurements showed high-grade paravalvular leakage of 45 and 58% regurgitant fraction, respectively. Intraoperatively, the dehiscence of more than half of the circumference of the aortic prosthesis was seen. This study shows that MRI can accurately assess even periprosthetic valve leakage with multiple regurgitation jets.

Adolescent↗
PubMedDate not supplied

Site of coronary sinus drainage does not significantly affect coronary flow reserve in patients long term after Fontan operation.

This study was designed to investigate the impact of postoperative coronary sinus drainage pressure on coronary flow reserve (CFR) assessed by Doppler guidewire in patients long term after Fontan operation. Twenty-nine patients (median age, 17.4 years female, 11) at a median of 10.6 years after Fontan operation were examined with intracoronary Doppler guidewire during cardiac catheterization. Fourteen patients had coronary sinus (CS) drainage to the systemic venous atrium and 15 patients had CS drainage to the pulmonary venous atrium after Fontan operation. Median CS drainage pressure was significantly higher in systemic venous CS drainage compared to pulmonary venous CS drainage (11 vs 5 mmHg, p < 0.0001). Median CFR values for the right and left coronary artery did not differ significantly with respect to CS drainage. There was a positive correlation between coronary flow reserve and pulmonary arteriolar resistance (p < 0.05) in multivariate regression analysis. The site of coronary drainage into the systemic atrium or the pulmonary venous atrium did not significantly affect CFR. Our data do not support a surgical strategy of elective redirection of coronary sinus blood to a low-pressure compartment but support an early staged approach. The positive correlation between CFR and pulmonary resistance demands further evaluation.

Adolescent↗
PubMedDate not supplied

Temporary pulmonary vein stenosis during intraoperative transesophageal echocardiography in total cavopulmonary connection.

Two patients operated on by one of the authors (MK) developed hemodynamic instability after otherwise uneventful completion of total cavopulmonary anastomosis with an extracardiac tube. In both, a stenosis of the right pulmonary veins was demonstrated during routine intraoperative transesophageal echocardiography. The transesophageal probe was found to be the underlying problem. Apparently, the pulmonary veins became compressed between the probe and the extracardiac conduit.

Aorta, Thoracic↗
PubMedDate not supplied

High field imaging of the normal pancreas.

Fifty MR scans conducted at 1.5 T were evaluated to assess how well the pancreas could be identified. A total of 128 sets of images were reviewed. The pancreatic head was identified in 81%, 82% and 74% of scans with T1, intermediate and T2-weighting, respectively. The body was identified in 100%, 96% and 70% and tail in 96%, 87% and 54% on those respective sequences. Relative contrast was calculated between pancreas and: liver, spleen, muscle, fat, stomach and small bowel. The variability seen in contrast compared to stomach and small bowel suggests that consistent MR visualization of the pancreas will probably necessitate the use of an oral contrast agent.

Adolescent↗
PubMedDate not supplied

Hemodynamic and morphologic evaluation of the spleen after splenic vein ligation in the dog.

The splenic vein was ligated in ten dogs in order to evaluate the time course of changes in splenic size and to relate them to splenic arterial flow, splenic pressure and development of venous collaterals. Following ligation of the splenic vein, splenic size and venous pressure immediately rose in all dogs. Arterial flow to the spleen simultaneously fell in roughly inverse proportion to the elevation of venous pressure. During the following weeks, the splenic parenchymal pressure decreased to basline levels in all but one dog, as collateral veins developed through the gastric venous network to the portal vein. Splenic size gradually decreased toward normal in eight of the ten dogs. At the time of sacrifice, 8-16 weeks after splenic vein ligation, pathologic examination demonstrated fibrosis from healed infarction. Recent hemorrhage, indicating persistence of the congestive process, we also present, although difficult to explain in view of normal splenic parenchymal pressure.

Animals↗
PubMedDate not supplied

MR evaluation of clinically suspected adnexal masses.

OBJECTIVE: Our goal was to determine the sensitivity, specificity, predictive value, and accuracy of pelvic MRI in the prospective evaluation of women with a clinically suspected pelvic mass. MATERIALS AND METHODS: One-hundred three patients with clinically suspected pelvic masses were prospectively evaluated by pelvic MRI. Masses were analyzed for size, location, morphological characteristics, and signal behavior. Masses were classified as benign, malignant, or indeterminate and in every case an attempt was made to generate a specific diagnosis according to previously reported characteristic MR appearances. Surgical follow-up was obtained within 3 months of MRI examination for all patients, excepting 11 patients with typically appearing leiomyomas. RESULTS: One hundred twenty pelvic masses were confirmed. Magnetic resonance was 100% sensitive and 99% specific in prospectively diagnosing dermoids, 96% sensitive and 100% specific in diagnosing subserosal leiomyomas, and 92% sensitive and 91% specific in diagnosing endometriomas. CONCLUSION: When physical examination or ultrasound examination is inconclusive, pelvic MRI can aid in the evaluation of women with a suspected pelvic mass. By identifying these common benign gynecologic conditions, unnecessary surgery can be avoided.

Adnexal Diseases↗
PubMedDate not supplied

Analysis of meiotic chromosomes in ejaculates of infertile patients with an increased number of immature germ cells in semen samples.

Seventy-one semen samples of 60 infertile patients with a suggested high number of immature germ cells were assigned for chromosomal analysis. The sperm probes of nine patients did not contain immature germ cell stages apart from spermatids. In 22 probands we could only find early prophase stages or not readable metaphase structures. Only 25 patients could be analysed cytogenetically. The semen sample of each patient contained degenerated germ cell structures associated with desynaptic and fragmented/pulverized metaphase cells. It follows that in each analysed probe we could detect anomalies which can be attributed to errors in the gametic development process and which are possibly connected with the existing teratozoospermia and oligozoospermia. The easy practicality for cytogenetic analysis represents the most important advantage of the described method. The analysis of immature germ cell stages in semen samples makes it possible to bypass or to reduce the incidence of tests biopsies for meiotic chromosome investigation.

Chromosome Aberrations↗
PubMedDate not supplied

First report of intramyocardial pH in man: I. Methodology and initial results.

Continuous in vivo measurements of intramyocardial pH (MpH) have not been previously obtained in man. To achieve this goal, we developed in our laboratory a new, steel-jacketed, glass electrode, and circumvented temperature-related problems by recording the output in millivolts along with the adjacent myocardial temperature. A computer program was devised to calculate MpH in accordance with the Nernst equation. The need in this system for a remote, subcutaneous, reference electrode prompted two sets of experiments. The first set of experiments demonstrated in vitro that the adverse effect of varying the temperature of the reference electrode on the calibration of the pH electrode could be avoided if the reference electrode was placed in a potassium chloride (KCl) solution outside the body and connected to the subcutaneous tissues with a salt bridge. The second set of experiments, which were conducted in vivo in dogs, demonstrated that MpH measurements made with the reference electrode in the limb were not affected by ischemic electrocardiographic changes. This system was then used successfully in 10 patients undergoing coronary artery bypass surgery. Reliable, reproducible, and uniform changes were observed. Baseline MpH prior to revascularization was 6.81 +/- 0.07. Myocardial protection with cold K+ cardioplegia resulted in a significant rise in MpH to 7.45 +/- 0.06. Throughout the period of cross-clamping, MpH remained high. After revascularization and discontinuation of cardiopulmonary bypass, MpH stabilized at 6.93 +/- 0.04.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗