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Biomedical subjects

T Walther

Publications and source records attributed to T Walther.

At least 127 records · Page 7Linked to original sources
PubMed1998

Absence of phospholipase A2 activity in genital Mycoplasma hominis.

The clinical relevance of vaginal colonization with Mycoplasma hominis (M hominis) as a cause of prematurity is doubtful. One of the possible pathways which could explain the role of M hominis in the induction of preterm labour is an increased synthesis of prostaglandins by a phospholipase A2 activity. The aim of this study was to prove whether M hominis secrets proteins with a PLA2 activity and to test whether there are strain differences in the enzyme activity between M hominis isolated from women with normal pregnancy and those with preterm labour. Using specific radio-immunoassay we could not measure any PLA2 activity in the supernatant of all investigated M hominis strains. We exclude the mechanism of induction of preterm labour by M hominis via an increased prostaglandin synthesis. Our findings make a relation between vaginal colonization with M hominis and prematurity unlikely.

Female↗
PubMed1998

C-type natriuretic peptide in maternal plasma in spontaneous labour, at elective cesarean section and during puerperium.

C-type natriuretic peptide (CNP) is the third member of the natriuretic peptide family that is involved in the regulation of blood pressure, renal function and volume homeostasis. In man CNP is highly expressed in endothelial cells, distinct brain areas and kidney. Maternal CNP plasma concentration remains stable in normal pregnancy with advancing gestational age. Using a radio-immunoassay we measured for the first time CNP plasma levels of women in the active phase of labour, during elective cesarean section in spinal anesthesia and in the postpartum period. Healthy pregnant women in the third trimenon were used as controls (7.36 +/- 3.0 pg/ml). CNP is significantly increased in labour (11.48 +/- 1.2 pg/ml) as well as after volume load before cesarean section (14.25 +/- 4.5 pg/ml). The postpartum concentration (9.3 +/- 2.4 pg/ml) was in the range of the controls. We conclude that CNP in plasma is increased during spontaneous labour. Its possible role in volume regulation with increased levels after rapid volume load but normal levels in puerperium with physiologically enhanced diuresis and natriuresis remains unclear.

Cesarean Section↗
PubMed1998

Detection of C-type natriuretic peptide in normal pregnancy.

C-type natriuretic peptide (CNP) is a recently identified member of the family of natriuretic peptides that plays an important role in the regulation of blood pressure, renal function and volume homeostasis. Its effects are mainly hypotensive and natriuretic. CNP is also considered to be an autocrine/paracrine regulator of the endothelium as well as a neuropeptide. Little is known about its role as a circulating substance. There are only few data of CNP plasma levels and changes in disease. Using a highly specific radioimmunoassay we established for the first time CNP plasma levels of normal pregnancies 5.9 +/- 1.5-8.6 +/- 2.1 pg/ml) and a non-pregnant control group (8.1 +/- 1.7 pg/ml). In contrast to atrial natriuretic peptide and brain natriuretic peptide we have not found significant differences of the plasma levels during normal pregnancy and no difference to the non-pregnant control group.

Atrial Natriuretic Factor↗
PubMed1998

A simple technique to isolate DNA and supernatant of genital Mycoplasma hominis and Ureaplasma urealyticum.

Vaginal colonization with Mycoplasma hominis and Ureaplasma urealyticum has been implicated as a cause of prematurity. Several mechanisms to induce preterm labor have been discussed. The investigation of expressed and secreted enzymes requires a feasible method for culturing and further processing of these bacteria. We describe a simple technique for culturing of Mycoplasma hominis and Ureaplasma urealyticum without contamination with other microorganisms and isolating DNA and supernatant. PCR amplification of a chromosomal Mycoplasma fragment was performed as positive control.

DNA, Bacterial↗
PubMed1997

[The aortic arch as the source of a peripheral arterial embolism].

HISTORY AND CLINICAL FINDINGS: On the day before admission a 68-year-old woman had an acute episode of incomplete ischaemia of the left lower arm. She had no known heart disease and her general condition was unchanged. There were no palpable pulses in the cold and pale lower arm. Sensory and motor functions of the left hand were slightly impaired. Arterial embolisation was suspected. INVESTIGATIONS: The blood picture was normal, erythrocyte sedimentation rate 20/50 mm, C-reactive protein elevated to 7.0 mg/l. There was no evidence of clotting abnormality. The resting ECG showed normal sinus rhythm. Doppler ultrasound gave a systolic pressure of 80 mm Hg over the radial artery and 50 mm Hg over the ulnar artery, with a systemic systolic pressure of 140 mm Hg. No intracardiac thrombi were seen on echocardiography. Transoesophageal echocardiography revealed a 2 x 3 cm hypermobile mass in the distal aortic arch, most likely a thrombus as the source of the embolus. Contrast computed tomography and digital subtraction angiography also demonstrated the mass. TREATMENT AND COURSE: At first heparin (bolus of 5000 IU, then 1000 IU/h) was infused. One day after the diagnosis had been established thrombectomy of the aortic arch and embolectomy of the left brachial artery were performed without complication. The patient was discharged on the 15th post-operative day on a maintenance dose of phenprocoumon. Histological examination of the surgical specimen from the aorta showed a separating thrombus on an ulcerating atherosclerotic plaque. CONCLUSION: The importance of the thoracic aorta as a source of emboli is often underestimated. Transoesophageal echocardiography is a reliable method to demonstrate aortic thrombi.

Aged↗
PubMed1997

Low-grade intimal hyperplasia in internal mammary and right gastroepiploic arteries as bypass grafts.

BACKGROUND: Knowledge is limited regarding the histology of the internal and right gastroepiploic arteries that have been functioning as coronary artery bypass conduits. METHODS: Four internal mammary arteries, 3 right gastroepiploic arteries, and 1 saphenous vein graft that had been functioning as coronary artery bypass grafts were harvested and examined histologically in 3 male patients who had died at 19, 38, and 47 months after coronary revascularization. RESULTS: All grafts were patent. The mean thicknesses of the intima in the proximal, middle, and distal segments were 41.0, 31.8, and 25.8 microns for the internal mammary artery and 58.0, 40.3, and 34.3 microns for the right gastroepiploic artery. The saphenous vein graft showed severe focal atherosclerosis. CONCLUSIONS: This histologic study in a small number of patients corroborates the reported excellent patency rates at medium- to long-term follow-up of the internal mammary and right gastroepiploic arteries used as coronary artery bypass grafts.

Aged↗
PubMed1997

Patch augmentation of regurgitant common atrioventricular valve in univentricular physiology.

BACKGROUND: Regurgitation of the common atrioventricular valve in patients with univentricular atrioventricular connection has a negative impact on outcome in the Fontan operation. Because severe regurgitation of the common atrioventricular valve may not be sufficiently reduced by a volume-reducing operation alone, the addition of a valvuloplasty may be a necessary adjunct to achieve competence of the common atrioventricular valve. A modified technique of valvuloplasty of the common atrioventricular valve and its medium-term results are presented. METHODS: Two infants and 1 young child with isomeric right atrial appendages, complete atrioventricular canal, univentricular atrioventricular connection with a double-inlet right ventricle through a common atrioventricular valve, pulmonary atresia (n = 2) or pulmonary stenosis (n = 1), and bilateral superior venae cavae presented with marked dilatation of the annulus of the common atrioventricular valve and severe regurgitation between the bridging leaflets. All 3 patients previously had been palliated with a generous central aortopulmonary shunt. The repair technique consisted of patch augmentation of the central bridging leaflets with an autologous pericardial patch. In addition, bilateral bidirectional cavopulmonary anastomoses were constructed and additional sources of pulmonary blood flow were eliminated. RESULTS: Intraoperative echocardiography demonstrated competence of the large central leaflet, excellent coaptation between the central leaflet and the bilateral mural leaflets, and decrease of the anteroposterior diameter of the annulus of the atrioventricular valve from 24, 29, and 34 mm preoperatively to 20, 23, and 29 mm, respectively. In all 3 patients, echocardiographic follow-up at 17, 14, and 6 months showed continued competence of the atrioventricular valve. CONCLUSIONS: Pericardial patch augmentation of the bridging leaflets may be a valuable adjunctive technique in the reconstruction of the regurgitant common atrioventricular valve in hearts with univentricular atrioventricular connection, especially if a volume-reducing operation alone does not result in competence of the valve.

Cardiac Surgical Procedures↗
PubMed1997

Thermal coronary angiography for intraoperative testing of coronary patency in congenital heart defects.

Intraoperative thermal coronary angiography was successfully applied in 9 patients who underwent operative correction of congenital heart defects: arterial switch operation for transposition of the great arteries (n = 5), Ross operation for valvar aortic stenosis with regurgitation (n = 3), and aortic implantation of the left coronary artery for anomalous connection of the left coronary artery to the pulmonary artery (n = 1). Intraoperative thermal coronary angiography allows early detection and surgical correction of coronary ostial obstruction.

Coronary Angiography↗
PubMed1997

Instantaneous subaortic outflow obstruction after volume reduction in hearts with univentricular atrioventricular connection and discordant ventriculoarterial connection.

OBJECTIVE: To study the phenomenon of potential subaortic outflow obstruction after surgical volume unloading of the heart in patients with univentricular atrioventricular connection, discordant ventriculoarterial connection, and bulboventricular foramen (BVF)-dependent systemic flow. MATERIAL AND METHODS: Intraoperative transesophageal echocardiography was used in five patients with tricuspid atresia (N = 3) or double-inlet left ventricle (N = 2) with rudimentary right ventricle and BVF who were scheduled to undergo a bidirectional cavopulmonary anastomosis (N = 3) or completion of the Fontan procedure after previous banding of the pulmonary artery (N = 2). The BVF diameter was measured in two orthogonal views, and the area was calculated by using the formula for an ellipse. Left ventricular posterior wall thickness and left ventricular internal diameter were also measured. Intraoperative prerepair and postrepair gradients across the BVF were measured by echocardiography. RESULTS: Volume unloading of the left ventricle resulted in instantaneous contraction of left ventricular size (decrease of median left ventricular internal diameter from 38 to 34 mm and increase of median left ventricular posterior wall thickness from 5 to 7 mm), decrease of median BVF area index (from 1.82 to 1.55 cm2/m2), and development of a median gradient of 60 mm Hg across the BVF. At a mean follow-up of 19.6 months, all patients were clinically well and had no echocardiographic evidence of BVF obstruction. CONCLUSION: In hearts with univentricular atrioventricular connection, discordant ventriculoarterial connection, and BVF-dependent systemic flow, a decrease in ventricular volume is associated with an instantaneous alteration in ventricular geometry, diminution in BVF size, and potential for subaortic outflow obstruction. Intraoperative transesophageal echocardiography is of paramount importance in excluding development of subaortic outflow obstruction in this setting.

Anastomosis, Surgical↗
PubMed1997

Stentless valve replacement in the small aortic root.

Despite the variety of different artificial heart valves available, no ideal prosthesis for the small aortic root has yet been identified. The aim of this study was to evaluate the haemodynamic performance and clinical outcome after stentless aortic valve replacement. A total of 70 patients with a small aortic root underwent Toronto (n = 61) or Freestyle (n = 9) stentless aortic valve replacement. All but three patients had aortic stenosis. Mean (s.d.) age at operation was 71.2(7.9) years. The mean annular diameter was 21.4(1.2) mm. Using controlled oversizing adjusting valve size to the sinotubular junction diameter, a 23-mm prosthesis was implanted in 23 patients and a 25-mm prosthesis in 47 patients. The maximum pressure gradient was 19.1(6.8) mmHg and effective valve orifice area was 1.47(0.27) cm2. At discharge and at follow-up, all patients were in New York Heart Association class I or II. At follow-up there was a significant reduction in pressure gradients, an increase in effective valve orifice areas, and decrease of pre-existing left ventricular hypertrophy. In conclusion, with controlled oversizing a gain in prosthesis size of 2 to 4 mm can be achieved. Implantation of oversized stentless valves leads to improved haemodynamics and to left ventricular remodelling in patients with a small aortic root.

Aged↗
PubMed1997

Abdominal aortic aneurysm repair during cardiopulmonary bypass: rationale for a combined approach.

Coronary artery disease and poor left ventricular function are the most important risk factors for morbidity and mortality in patients undergoing abdominal aortic aneurysm repair. Effective screening programmes and prior revascularization procedures (percutaneous translumincal coronary angiography and coronary artery bypass graft surgery) have helped to decrease the risk of cardiac-related adverse events. There is, however, a subgroup of patients presenting with both severe coronary artery disease and/or severely impaired left ventricular function and an acutely expanding or extremely large aneurysm that represents a therapeutic challenge. Surgery is often denied to these patients for their high risk. For this selected subgroup combined coronary artery bypass graft surgery and abdominal aortic aneurysm repair rather than a staged approach represents a therapeutic alternative. This article summarizes the pathophysiological concept, that favours a simultaneous approach performing abdominal aortic aneurysm repair during cardiopulmonary bypass and updates the current indications and results for this extensive surgery.

Aortic Aneurysm, Abdominal↗
PubMed1997

Trapped thrombus in a patent foramen ovale.

We report two cases of impending paradoxical embolism through a patent foramen ovale. A 73-year-old male had recurrent pulmonary embolism and a large thrombus trapped in a patent foramen ovale. The other patient, a 70-year-old male had septic mediastinitis after prior bypass surgery and a large thrombus lodged in a patent foramen ovale. Cardiac embolectomy and closure of the foramen ovale was performed in both cases because of impending paradoxical embolism. In addition pulmonary thromboendarterectomy was performed to relieve pulmonary hypertension. Therapeutical options are discussed.

Aged↗
PubMed1997

Discrepancy of sizers for conventional and stentless aortic valve implants.

BACKGROUND AND AIM OF THE STUDY: As the hemodynamic performance of an artificial heart valve is closely related to the size of the valve implanted, exact sizing of the prosthesis is important in aortic valve replacement. In the past, discrepancies have been recognized between the actual and labeled diameters of sizers used for conventional aortic valves; this study aimed to examine the accuracy of sizers for both conventional and stentless valves. METHODS: Currently used sets of sizers were analyzed using a high-precision digital micrometer with a resolution of 0.01 mm. Sizers of aortic bileaflet mechanical valves (ATS, CarboMedics, St. Jude Medical Standard, St. Jude Medical HP), conventional aortic bioprostheses (Carpentier Edwards) and stentless aortic bioprostheses (Freestyle, TorontoSPV) were analyzed. The diameters were recorded when the sizer could not be moved laterally while still able to be rotated. RESULTS: Results are given as mean +/- standard deviation for 20 repeat measurements. All mechanical valve sizers were 0.77 +/- 0.03 to 1.01 +/- 0.02 mm larger than labeled, whereas all bioprosthetic valve sizers proved to be sized as labeled (0 +/- 0.01 mm). CONCLUSIONS: Exact sizing is important in stentless valve replacement. The use of accurate sizers is recommended with other types of replacement valves as well. Results of valve replacement procedures worldwide would be more comparable if sizers of identical size were available in all operating rooms. As long as discrepancies between different sizers still exist, surgeons must be made aware of the problem.

Aortic Valve↗