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Biomedical subjects

A Moritz

Publications and source records attributed to A Moritz.

At least 19 recordsLinked to original sources
PubMed2006

Approaching actinide(+III) hydration from first principles.

A systematic computational approach to An(III) hydration on a density-functional level of theory, using quasi-relativistic 5f-in-core pseudopotentials and valence-only basis sets for the An(III) subsystems, is presented. Molecular structures, binding energies, hydration energies, and Gibbs free energies of hydration have been calculated for [An(III)(OH(2))(h)](3+) (h = 7, 8, 9) and [An(III)(OH(2))(h-1) * OH(2)](3+) (h = 8, 9), using large (7s6p5d2f1g)/[6s5p4d2f1g] An(III) and cc-pVQZ O and H basis sets within the COSMO implicit solvation model. An(III) preferred primary hydration numbers are found to be 8 for all An(III) at the gradient-corrected density-functional level of theory. Second-order Møller-Plesset perturbation theory predicts preferred primary hydration numbers of 9 and 8 for Ac(III)-Md(III) and No(III)-Lr(III), respectively.

Actinoid Series Elements↗
PubMed2006

MR-based coronary artery blood velocity measurements in patients without coronary artery disease.

To evaluate the feasibility of MR-based coronary blood velocity measurements (MRvenc) in patients without coronary artery disease (CAD). Eighty-three patients with angiographically excluded CAD received MRvenc of the proximal segments of both coronary arteries (CAs). Using a retrospectively ECG-gated breath-hold phase-contrast FLASH sequence with high temporal resolution, flow data were technically acquirable in 137/166 (83%) CAs. Quantification and analysis of blood velocities in systole and diastole of both CAs were performed. Biphasic velocity profiles were found in 83/100 CAs. Median systolic and diastolic velocities differed significantly in LCA (19 cm/s, 24 cm/s; P<0.0001) and RCAs (14 cm/s, 16 cm/s; P<0.01). The diastolic/systolic velocity ratio was calculated in LCAs and RCAs with a median of 1.3 and 1.1, respectively. The velocity profiles of the remaining CAs were monophasic (17 CAs) or revealed severe alterations of the physiologic velocity profile with reduced flow undulations and steady velocities (37 CAs). Optimized clinical MRvenc is feasible to quantify blood velocities in the CAs. Potential indications are (1) non-invasive monitoring of patients after aortic valve reconstruction as well as (2) detection of asymptomatic CAD patients.

Adult↗
PubMed2006

[Aprotinin in cardiac surgery: more risks than usefulness?].

Antifibrinolytic therapy with the serine protease inhibitor Aprotinin or the lysine analogues epsilon-aminocapronic acid or tranexamic acid is a therapeutic measure to reduce perioperative blood loss during cardiac surgery. In an international, prospective, non-randomised phase 4 observation study, Mangano et al. investigated the effectiveness and side-effects of Aprotinin, epsilon-aminocapronic acid and tranexamic acid in comparison to no antifibrinolytic therapy in a total of 4,374 patients who underwent cardiac surgery with extracorporeal circulation. In the opinion of Mangano et al. the results of this study question the safety and effectiveness of Aprotinin for reduction of perioperative blood loss by cardiac surgery patients. Despite a critical review of the study and results reported by Mangano et al., the authors of the present paper come to the conclusion that, in view of the availability of more reasonably priced alternatives in Germany, it appears to be sensible to give preference to tranexamic acid instead of aprotinin.

Aminocaproates↗
PubMed2006

Does totally endoscopic access for off-pump cardiac surgery influence the incidence of postoperative atrial fibrillation in coronary artery bypass grafting? A preliminary report.

BACKGROUND: The occurrence rate of atrial fibrillation (AF) after coronary artery bypass grafting, quoted in the literature, is wide ranging from 5% to over 40%. It is speculated that, off-pump coronary artery bypass grafting (OPCAB) and also minimally invasive cardiac surgery reduces the incidence of postoperative AF due to reduced trauma, ischemia, and inflammation. Current data, however, do not clearly answer the question, whether the incidence of postoperative AF is reduced in using minimally invasive techniques, ideally resulting in the combination of both small access and off-pump surgery. The aim of this study was to evaluate the incidence of postoperative AF in patients undergoing totally endoscopic off-pump coronary artery bypass grafting (TECAB). METHODS: A retrospective analysis of 72 patients undergoing myocardial revascularization was performed. Early postoperative incidence of AF was compared between three groups of patients: 24 after conventional coronary artery bypass grafting (CABG), 24 after OPCAB, and 24 after totally endoscopic off-pump CABG. Clinical profile of the patients, including factors having potential influence on postoperative AF was matched for groups. RESULTS: Postoperative AF occurred in 25% of the patients in the CABG group, in 16% of the patients in the OPCAB group, and in 16% of the patients in the TECAB group. This difference has no statistical significance. Risk factors and incidence of postoperative complications were comparable in all groups excepting the number of distal anastomoses. There was a statistical significance between CABG group and TECAB group. CONCLUSION: Avoiding cardiopulmonary bypass and minimizing surgical trauma did not reduce the incidence of postoperative AF in this patient collective. It remains an attractive hypothesis that postoperative AF is reduced by off-pump myocardial revascularisation and minimizing surgical trauma but more robust data are required.

Aged↗
PubMed2006

Left atrial size reduction improves the sinus rhythm conversion rate after radiofrequency ablation for continuous atrial fibrillation in patients undergoing concomitant cardiac surgery.

BACKGROUND: Radiofrequency (RF) ablation can effectively restore sinus rhythm in the majority of patients with continuous atrial fibrillation (AF). However, no previous randomized studies have discussed the association of left atrial size reduction and the improvement of sinus rhythm conversion rate after radiofrequency ablation for continuous AF. METHODS: This prospective randomized study included 46 patients with continuous AF and cardiac disease. Twenty patients underwent cardiac surgery and radiofrequency ablation (group I). The other 26 patients underwent cardiac surgery and RF ablation combined with left atrial size reduction (group II). The patients were followed for one year postoperatively. Rhythm, neurological complications, and left atrial size were evaluated. RESULTS: At the one-year follow-up sinus rhythm was restored in 61.1 % of patients in group I and 77.3 % of patients in group II. LA diameter, evaluated by echocardiography, was reduced from 60 +/- 15 mm to 55 +/- 8 mm in group I and from 69 +/- 19 mm to 51 +/- 8 mm in group II. One case of stroke was observed postoperatively in each group. In group I one patient suffered a transient ischemic attack. Two patients in each group received transvenous permanent pacemaker implantation. CONCLUSION: Left atrial size reduction improves sinus rhythm conversion rate after RF ablation for continuous atrial fibrillation in patients undergoing concomitant cardiac surgery.

Adult↗
PubMed2006

Detection of vein graft disease using 4-row computed tomography. Evaluation of coronary bypass graft patency and correlation with the Ca-score.

BACKGROUND: Multi-row computed tomography (MDCT) is a promising non-invasive technique and capable of rapid imaging of cardiac structures, including coronary arteries and bypass grafts during a single held breath. In this study, we evaluated coronary artery bypass graft (CABG) patency by comparing 4-slice computed tomography with conventional contrast angiography. One disadvantage of MDCT is the limited diagnostic accuracy with + increased calcification of the grafts. Therefore, the correlation between Ca-grading and diagnostic accuracy was examined. METHODS: We examined 30 patients with 104 bypass grafts with a 4-row MDCT scanner. On the basis of the Ca-score, patients were divided into 3 groups. RESULTS: It was possible to assess the exact degree of stenosis in 25 of 32 > 50% stenoses with 4-row MDCT, 7 stenoses were underestimated. All occlusions in 21 patients were identified correctly, 33 graft segments were underestimated in MDCT, of which 28 were in the group with a Ca-score of > 800. CONCLUSIONS: MDCT allows non-invasive angiographic evaluation of coronary bypass grafts with a high diagnostic accuracy. However, the method strongly depends on the degree of vascular calcification and underrates the degree of stenosis subject to the Ca-score. This is a distinct limitation in distal vascular segments of small calibre which cannot be validly displayed. In patients with low or moderate Ca-score values, MDCT coronary angiography is promising new technique with a high diagnostic accuracy for the detection of graft stenosis or occlusions.

Aged↗
PubMed2006

Decalcification of the mitral annulus: surgical experience in 81 patients.

OBJECTIVE: Mitral valve surgery in the presence of extensive calcification of the mitral annulus is a technical challenge and increases perioperative risk. This study reviews our experience with decalcification of the mitral annulus in patients undergoing mitral valve reconstruction or replacement. METHODS: From 1995 to 2003, 81 patients (mean age 64 +/- 13 years, 30 male, 51 female) with extensive calcification of the mitral annulus underwent mitral valve repair (n = 42) or replacement (biological n = 20, mechanical n = 19). The mean follow-up was 24 months. Patients presented with a mean EuroSCORE of 7. Concomitant surgical procedures were performed in 62 %. Patient outcomes were retrospectively assessed. RESULTS: Perioperative survival was 97.5 % (n = 79) and hospital survival was 91.3 % (n = 74). Two-year survival was 88.9 %. Eight patients needed reexploration due to bleeding and five patients required prolonged mechanical ventilation. No perioperative stroke was observed. Freedom from reoperation was 90.2 % (n = 73). Early reoperation for recurrent incompetence was necessary in 3 patients and late reoperation in 5 patients. CONCLUSIONS: Despite the elevated perioperative risk and the high risk of reoperation with this procedure, decalcification of the annulus and repair/replacement of the mitral valve could be performed with good clinical results.

Adolescent↗
PubMed2006

Behavior of gaseous microemboli in extracorporeal circuits: air versus CO2.

BACKGROUND: Open heart surgery is associated with serious risk of cerebral and peripheral organ dysfunction, attributed in part to air microbubbles generated in or not eliminated from the extracorporeal circuit (ECC). Venous air leakage leads to increased arterial bubble load. CO2 replacing air in cardiac chambers show faster resorption times, reducing possible cerebral or peripheral organ damage after heart valve interventions. In two models of ECC the effect of air entering closed circuits was demonstrated and compared to the effect of CO2 entry. METHODS: Fragmentation and dissolution of gas (0.5 mL) was evaluated in an in vitro model of ECC, using ultrasonic bubble detection. Air leakage (10 mL) in the venous line of the ECC was simulated and compared to the effect of the same quantity of CO2 entering the circuit. Both models used whole blood priming and physiological conditions, verified with blood gas analyses. RESULTS: Fragmentation and dissolution of gas bubbles injected into a closed ECC could be demonstrated, complete resorption of CO2 bubbles was observed earlier than complete resorption of room air (5.0+/-0.6 vs. 14.4+/-5.9 min, p=0.0009). CO2 entering the venous line lead to 40% less arterial bubble load as compared to the same amount of room air entering the circuit (2099+/-991 vs. 3555+/-632, p=0.005). CONCLUSIONS: Current ECC systems fail to eliminate gas entering the circuit, leading rather to microbubble dispersion. CO2 is much faster resorbed within the circuit than room air. In open heart surgery as valvular operations, CO2 insufflation into the operative field is protective, as we have demonstrated in our models.

Air↗
PubMed2005

Assessment of the distal anastomosis of coronary artery bypass grafts with a 2D T2-weighted turbo spin echo sequence and correlation to conventional coronary angiography.

OBJECTIVE: The aim of the study was to evaluate the patency of the distal anastomoses of coronary artery bypass grafts and to detect graft stenoses and occlusions with a magnetic resonance (MR) spin echo sequence. PATIENTS AND METHODS: One hundred and eighty-five patients with 481 distal anastomoses were examined with a 1.5 T MR scanner and coronary angiography. A 2-dimensional T2-weighted breath-hold half-Fourier acquisition single-shot turbo spin echo sequence (Haste) was performed. All images were evaluated independently by a radiologist and cardiologist and compared to the conventional coronary angiography. The observers were blinded to the coronary angiography findings, but informed in regard to the surgical graft anastomosis. RESULTS: With the Haste sequence, 76% of the distal anastomoses were recognized (368/481). Forty-five of 52 (87%) stenoses and all occlusions were identified. The sensitivity and specificity for the evaluation of the distal anastomosis with the spin echo sequence was 87% and 96%. Twenty-four percent of the distal anastomoses were not identified due to a poor image quality or motion artefacts. CONCLUSION: Using the Haste sequence, a reliable assessment of graft patency of the distal anastomosis is possible. Further improvements of the spatial resolution and the image quality are necessary to recommend this MR technique for routine clinical use.

Adult↗
PubMed2005

Flow cytometric analysis of effusions in dogs and cats with the automated haematology analyser ADVIA 120.

Samples were aspirated from 12 thoracic effusions, 10 abdominal effusions and four pericardial effusions in 17 dogs and nine cats. They were analysed cytometrically with the ADVIA 120 flow cytometer and the results were compared with the results of cytological examinations of May-Grünwald-Giemsa-stained smears. The conventional cytology revealed a purulent or pyogranulomatous inflammation in 12 of the animals, lymphoma in six, malignant histiocytosis in two, and an unspecified carcinoma in two; two animals had a chylous effusion, two had a modified transudate, and one dog had an idiopathic pericardial haemorrhage. The flow cytometric analysis was based on cellular volume, peroxidase staining intensity and the determination of nuclear lobularity, and made it possible to identify predominant cell lineages and cell debris, which were shown in characteristic cytograms. Inflammatory effusions, monocytic proliferation and lymphoma were easily detected, but carcinoma cells and mesothelial cells were classified as 'mononuclear blasts'.

Animals↗
PubMed2005

Moderate hypothermia (30 degrees C) for surgery of acute type A aortic dissection.

OBJECTIVE: Antegrade cerebral perfusion has proved to be a reliable method of brain protection during surgery of thoracic aneurysms. In addition, the drawbacks of deep hypothermia may be avoided. This study examines the outcome after surgery for acute type A aortic dissections (AAD) using moderate (30 degrees C) systemic hypothermia compared with conventional techniques of cerebral protection. METHODS: Between January 1999 and August 2003, 74 patients underwent repair of acute type A aortic dissection. Moderate systemic hypothermia (30 degrees C) with selective antegrade cerebral perfusion through subclavian artery (group A) was used in 18 patients. Deep hypothermia (20 - 24 degrees C) was employed using either retrograde (18 patients, group B) or antegrade (38 patients, group C) cerebral perfusion. Tube graft replacement was performed in 55, valve-sparing procedure in 8, and composite graft replacement in 11 patients. RESULTS: The 30-day mortality was 5.5 % in group A, 5.5 % in group B, and 15.8 % in group C (A vs. C and B vs. C; p < 0.01). New postoperative permanent neurologic deficit occurred in 5.5 % of patients in group A, 16.7 % in group B, and 13.2 % in group C. Mean chest tube drainage within the first 24 h in groups A, B and C was 703 +/- 338, 1178 +/- 820, and 1447 +/- 802 ml, respectively (A vs. B and A vs. C; p < 0.01). Cardiopulmonary bypass, ICU, and hospital times were significantly shorter in group A. CONCLUSIONS: Selective antegrade cerebral perfusion with moderate systemic hypothermia appears to be a safe and sufficient tool for brain protection during AAD repair. In avoiding deep hypothermia, this technique may help to reduce cardiopulmonary bypass time and hypothermia-related side effects.

Aortic Dissection↗
PubMed2005

A giant rhabdomyoma with left ventricular inflow occlusion and univentricular physiology.

During a routine prenatal ultrasound a huge tumor was diagnosed located in the left ventricle and left atrium with complete obstruction of the left ventricular inflow tract. On the first day of life, urgent surgical intervention was necessary because of progressive heart failure with univentricular physiology. Intraoperatively, the tumor mass was found to originate from the left ventricular wall, reaching into the left atrium. Histological examination revealed a rhabdomyoma.

Cardiac Surgical Procedures↗
PubMed2005

Development of a PCR-based diagnostic test detecting a nt230(del4) MDR1 mutation in dogs: verification in a moxidectin-sensitive Australian Shepherd.

A subpopulation of dogs of the Collie and Australian Shepherd breeds show increased sensitivity to central nervous actions of ivermectin, doramectin, loperamide, and probably several other drugs. The molecular background for this greater sensitivity is a nonsense mutation in the MDR1 efflux pump, which is part of the functional blood-brain barrier and normally limits drug penetration into the brain. This report describes a rapid PCR-based method for detection of this nt230(del4) MDR1 mutation using a small amount of genomic DNA from blood cells. Thereby, homozygous intact, homozygous mutated, and heterozygous mutated MDR1 genotypes can be clearly differentiated by high resolution polyacrylamide gel electrophoresis. Using this diagnostic test two Collies and one Australian Shepherd were screened for the nt230(del4) MDR1 mutation. The Collies had no history of altered drug sensitivity and showed homozygous intact and heterozygous mutated MDR1 alleles, respectively. However, the Australian Shepherd developed clear signs of neurotoxicity including ataxia, crawling, acoustic and tactile hyperexcitability, and miosis after a single dose of moxidectin (400 microg/kg). For this dog two mutated MDR1 alleles were detected. This report describes for the first time moxidectin neurotoxicosis in a dog with a homozygous MDR1 mutation.

Administration, Oral↗
PubMed2005

Frequency of the nt230 (del4) MDR1 mutation in Collies and related dog breeds in Germany.

MDR1 (ABCB1) P-glycoprotein exerts a protective function in the blood-brain barrier thereby limiting the entry of many drugs and other xenobiotics to the central nervous system. A nonsense mutation has been described for Collies and related dog breeds which abolishes this function and is associated with increased susceptibility to neurotoxic side effects of several drugs including ivermectin, moxidectin and loperamide. In order to evaluate the occurrence and frequency of this nt230 (del4) MDR1 mutation in Germany, we screened 1500 dogs. Frequency of the homozygous mutated genotype was highest for Collies (33.0%), followed by Australian Shepherd (6.9%) and Shetland Sheepdog (5.7%). Thirty-seven percent of the Wäller dogs and 12.5% of the Old English Sheepdogs were heterozygous for the mutant MDR1 (-) allele. Considering the predominant role of MDR1 P-glycoprotein in drug disposition and in particular for blood-brain barrier protection, MDR1 genotype-based breeding programs are recommended for improving the safety of drug therapy in these canine breeds.

Animals↗
PubMed2004

Totally endoscopic coronary artery bypass graft: initial experience with an additional instrument arm and an advanced camera system.

BACKGROUND: Robotically enhanced telemanipulation for totally endoscopic coronary artery bypass does not provide adequate tactile feedback, traction, or countertraction. The exposition of coronary target sites is difficult, the visual field is limited, and the epicardial stabilization may be troublesome. A fourth robotic arm for endothoracic instrumentation has been added to the da Vinci surgical system to facilitate totally endoscopic operations. The stereoendoscope was upgraded with a wide-angle feature. METHODS: The procedure was performed in five patients. Four of these patients had left internal thoracic artery (LITA) to left anterior descending artery (LAD) grafting on the beating heart and the fifth had sequential bypass grafting (LITA to diagonal branch and LAD) on an arrested heart. The additional effector arm of the da Vinci surgical system was brought into the operative field beneath the operating table and used as a second right arm. The wide-angle view was activated by either the console or the patient side surgeon. RESULTS: The mean operative, port placement, and anastomotic times for a beating-heart totally endoscopic coronary artery bypass were 195 +/- 58, 25 +/- 10, and 18 +/- 5 min, respectively. All procedures were free of morbidity and mortality, with satisfactory angiographic control. The sequential arterial bypass grafting procedure was fully completed in totally endoscopic technique. CONCLUSIONS: The additional instrumentation arm and wide-angle visualization are useful technical improvements of the da Vinci surgical system, solving the problem of traction, countertraction, and facilitated exposition of target sites as well as visualization of the surgical field. They provide potential for wider acceptance of totally endoscopic coronary artery bypass grafting in a larger surgical community.

Aged↗
PubMed2004

Improved cerebral protection through replacement of residual intracavital air by carbon dioxide: a porcine model using diffusion-weighted magnetic resonance imaging.

BACKGROUND: Major risk of central or peripheral organ damage is attributed to air embolism from incompletely de-aired cardiac chambers after cardiac operations. Replacement of air by carbon dioxide insufflation into the thoracic cavity is widely used. Diffusion-weighted magnetic resonance imaging of the brain detects ischemia within minutes after onset. The reversibility of ischemia in cerebral tissue after massive gaseous emboli has not yet been described. METHODS: After selective catheterization of a common carotid artery in 15 pigs, boli of 1 mL/kg body weight of air (n = 5) or carbon dioxide (n = 5, "low dose") were applied. Five pigs received 2 mL/kg body weight of carbon dioxide ("high dose"). Diffusion-weighted magnetic resonance imaging of the brain was performed 2, 5, 10, 15, and 25 minutes after embolization. RESULTS: All animals of the "air" group showed important circulatory reactions leading to death of 2 animals. In the whole group, diffusion-weighted magnetic resonance imaging revealed irreversible hyperintense signals in both hemispheres. In the low-dose group, no change in signal intensity was observed in 2 pigs, and 3 others showed reversible changes in signal intensity, without important circulatory reactions. In 3 animals of the high-dose group, hyperintense signals were reversible, but 2 others presented with bilateral, irreversible signals in diffusion-weighted magnetic resonance imaging, accompanied by minor circulatory reactions. CONCLUSION: In contrast to the dramatic effect of air emboli, identical quantities of carbon dioxide injected into cerebral arteries of the pigs were not associated with major clinical symptoms. The early reversibility of ischemic reactions visualized in diffusion-weighted magnetic resonance imaging encourages the use of carbon dioxide insufflation as a protective method in cardiac surgery.

Animals↗