PubMed Health⌕ Search

Biomedical subjects

L Sieverding

Publications and source records attributed to L Sieverding.

At least 19 recordsLinked to original sources
PubMed2007

Stereolithographic reproduction of complex cardiac morphology based on high spatial resolution imaging.

BACKGROUND: Precise knowledge of cardiac anatomy is mandatory for diagnosis and treatment of congenital heart disease. Modern imaging techniques allow high resolution three-dimensional (3D) imaging of the heart and great vessels. In this study stereolithography was evaluated for 3D reconstructions of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) data. METHODS: A plastinated heart specimen was scanned with MDCT and after segmentation a stereolithographic (STL) model was produced with laser sinter technique. After scanning the STL model with MDCT these data were compared with those of the original specimen after rigid registration using the iterative closest points algorithm (ICP). The two surfaces of the original specimen and STL model were matched and the symmetric mean distance was calculated. Additionally, the heart and great vessels of patients (age range 41 days-21 years) with congenital heart anomalies were imaged with MDCT (n=2) or free breathing steady, state free-precession MRI (n=3). STL models were produced from these datasets and the cardiac segments were analyzed by two independent observers. RESULTS: All cardiac structures of the heart specimen were reconstructed as a STL model within sub-millimeter resolution (mean surface distance 0.27+/-0.76 mm). Cardiac segments of the STL patient models were correctly analyzed by two independent observers compared to the original 3D datasets, echocardiography (n=5), x-ray angiography (n=5), and surgery (n=4). CONCLUSIONS: High resolution MDCT or MRI 3D datasets can be accurately reconstructed using laser sinter technique. Teaching, research and preoperative planning may be facilitated in the future using this technique.

Adolescent↗
PubMed2006

[Echocardiographic diagnosis of the aorto-pulmonary window].

UNLABELLED: PURPOSE/MATERIALS AND METHODS: The aorto-pulmonary window is a rare congenital cardiac malformation consisting of a connection between the ascending aorta and the main pulmonary artery. Based on 5 consecutive patients who were treated in our tertiary referral centre between 7/2000 and 11/2005, we report the echocardiographic features as well the limitations of this diagnostic method in the assessment of this rare malformation. RESULTS: Dilation of the left atrium and ventricle due to the large left-to-right-shunt was the characteristic echocardiographic feature in all patients with aorto-pulmonary window. In all patients we were able to visualise the window by 2D-echocardiography. Pulsed- and continuous-wave Doppler showed diastolic negative flow in the descending aorta and in systemic arteries due to left-to-right shunting in diastole via the aorto-pulmonary window. All 5 patients had significant associated cardiovascular malformations. They were accurately diagnosed by echocardiography. Coronary anomalies could be excluded noninvasively in all patients. CONCLUSION: Echocardiography is the method of choice for diagnosis of aortopulmonary window. Detection of aortopulmonary window, however, requires a systematic and careful investigation of all cardiovascular anatomic details, since this anomaly is frequently associated with substantial additional cardiac anomalies, which would by themselves be sufficient to explain the haemodynamic abnormalities of the patient. Cardiac catheterisation is required only in cases with inadequate information about coronary artery anatomy or in older patients with pulmonary hypertension, to determine the patient's suitability for surgical correction.

Aorta, Thoracic↗
PubMed2005

Recanalisation of bilateral superior vena cava after total cavopulmonary connection. Interventional occlusion with the Amplatzer VSD Occluder.

UNLABELLED: Formation of systemic to pulmonary venous or systemic venous left atrial collaterals frequently occurs in patients after Glenn or Fontan-type operations. Embolization with detachable metal coils is the therapy of choice for the closure of small vessels. These devices however are not appropriate for the occlusion of large collaterals, e. g. recanalized bilateral caval veins. We report two patients who presented late after Fontan-type operations with a gradual decrease in oxygen saturation due to recanalisation of bilateral caval veins. Interventional closure of these large veins was carried out successfully with the use of 8 mm Amplatzer muscular VSD Occluders, resulting in an increase of arterial oxygen saturations. CONCLUSION: The closure of recanalized bilateral superior caval veins after Fontan procedures is possible without technical problems by means of the Amplatzer muscular VSD Occluder. In order to avoid future formation of venous collaterals via the azygos or hemiazgos system, the occluder should be placed in the vena cava below the orifice of the azygos/ hemiazygos vein.

Adult↗
PubMed2004

[Clinical implication of parameter-optimized 3D-FISP MR angiography (MRA) in children with aortic coarctation: comparison with catheter angiography].

PURPOSE: To implement parameter-optimized 3D-FISP MR angiography (MRA) with interleaved double-slab excitation and to compare the result with catheter angiography in children with aortic coarctation. MATERIALS AND METHODS: Eighteen children aged 2 - 15 years (mean 9.1 years) underwent MR imaging on a 1.5T body scanner (Magnetom Vision, Siemens, Germany). All patients had undergone correlative catheter angiography. T1-weighted turbo spin echo (TSE) images (TR 600 ms, TE 17 ms, flip 160 degrees, slice thickness 2 - 4 mm) were obtained in axial and parasagittal orientation, followed by an optimized 3D-FISP MR angiography in a sagittal plane (TR 12.5 ms, TE 5.5 ms, flip 22 degrees, matrix 256 x 256, slice thickness 1.25 mm). All children were sedated but on spontaneous breathing. Image quality was graded by two experienced reviewers using a 4-point scoring system. Source images and reformatted maximum intensity projections (MIP) were analyzed for blood-tissue contrast as well as size and focal stenoses of the aortic arch. RESULTS: Aortic coarctation was found in 13 of 18 patients, using the 3D-FISP MRA. A high correlation value (r = 0.96) was found compared to catheter angiography. Image quality was high in 94 % with well defined blood-tissue contrast in all cases. The sensitivity to flow and breathing motion was low. Examination time was about 15 minutes depending on volume of interest and heart rate. Diagnostic accuracy has shown improvement using a combined analysis of source and MIP images. The mentioned technique has provided an excellent display of thoracic vasculature. CONCLUSION: MR imaging represents an excellent tool for non-invasive examination of the cardiovascular system of children. The 3D-MRA allows the recording of a large 3D data set without the use of contrast agent and within an adequate measurement period, particularly in small infants unable to hold their breath. In addition, hemodynamic significance of aortic coarctation, the existence of collateral vessels and other congenital heart diseases can be described reliably by using this technique.

Adolescent↗
PubMed2003

[Asymptomatic cor triatriatum in a 2 1/4 year old patient].

We report on an asymptomatic 2 1/4 year old girl. Echocardiography revealed cor triatriatum with a membrane separating the left atrium. Transesophageal echocardiography demonstrated 3 large perforations of the intraatrial membrane. Using Doppler sonography, no pressure gradients across these orifices were identified. Obstruction of the intraatrial membrane and pulmonary hypertension were excluded by cardiac catheterization. We therefore decided against surgical resection of the membrane and to follow the patient noninvasively by echocardiography. Follow-up over 18 months revealed no development of an obstruction across the intraatrial membrane. Our case shows that immediate surgical correction is not necessary in all patients with cor triatriatum. Conservative management of these patients requires full evaluation of the hemodynamics and careful follow-up examinations by echocardiography.

Child, Preschool↗
PubMed2002

Prenatal diagnosis and perinatal management of left coronary artery to right atrium fistula.

Serious complications due to coronary artery fistulae have been described. Most authors recommend early intervention at the time of diagnosis. We present a case of a fistula originating from a dilated left coronary artery and draining into the right atrium, which was diagnosed prenatally by color Doppler echocardiography. During pregnancy, the echocardiographic findings remained unchanged, and there were no signs of heart failure. After birth, the fistula was confirmed by angiography. Additionally, a persistent left superior vena cava draining into the coronary sinus and a very small ventricular septal defect were detected. The fistula was closed successfully by transcatheter coil embolization. At 17 months old the child was in good clinical condition. Prenatal diagnosis of coronary artery fistulae may be possible and may improve perinatal management and outcome.

Adult↗
PubMed2001

Incidence and impact of systemic venous collateral development after Glenn and Fontan procedures.

BACKGROUND: Development of systemic venous collaterals after Glenn or Fontan procedures can lead to systemic desaturation and reduction in ventricular function, resulting in impaired everyday performance in patients with univentricular heart disease. METHODS: We analyzed 79 patients who had undergone a Glenn or Fontan procedure between 1995 and 1999 for the incidence and predilection sites of systemic venous collaterals as well as the therapeutic options. RESULTS: In 16/79 (= 20.2%) patients, 19 veno-venous connections were detected 310 days (1-966 days) postoperatively. Locations were: brachiocephalic angles/pericardial veins (7), azygos/hemiazygos system (5), Thebesian veins (2), epidiaphragmatic veins (5). Drainage was to the pulmonary veins in 5, to the "left" atrium in 9, and to the IVC system in 5 patients. An isolated intervention became necessary because of low saturations in 5/16 pts, with improvement in all of them (catheter embolization 4, surgical closure 1). CONCLUSIONS: After Glenn or Fontan operations, the increased central venous pressure may induce recanalization of embryologically preformed and obliterated vessels. Their predilection sites must be carefully evaluated pre- and postoperatively. During surgical procedures, potential venous channels should be ligated. Interventional or surgical closure of collaterals may become necessary.

Adolescent↗
PubMed2001

[Echocardiographic findings before and after interventional occlusion of persistently patent ductus arteriosus with the amplatzer duct occluder].

AIM: The Amplatzer duct occluder(R) is a new system for interventional occlusion of persistently patent ductus arteriosus. The purpose of our study was to determine, whether adequate evaluation of this occluder system can be obtained by echocardiography. METHOD: From 11/1999 until 12/2000, 18 patients were included in the study. All underwent interventional occlusion of a patent ductus arteriosus with the Amplatzer duct occluder(R). Echocardiography was performed on admission, on day one and three and six months following the intervention. RESULTS: The mean age of our patients was 4.8 years (9 months - 18.7 years, median 3.2 years), the mean weight was 18.4 kg (6.5 - 66 kg, median 14 kg). All echocardiographic findings prior to intervention were confirmed during cardiac catheterization. Following intervention we were able to visualize the occluder system and its relation to surrounding structures in all patients. In none of our patients we found an obstruction of the left pulmonary artery. In 1/18 patients there was a minor protrusion of the distal occluder into the descending aorta. Doppler-sonography however revealed no obstruction. Complete occlusion of the ductus arteriosus was confirmed by color Doppler echocardiography in all patients within 5 days, in 17/18 patients no residual shunt was detectable within 24 hours. CONCLUSION: According to our experience the results of interventional occlusion of patent ductus arteriosus in children and adolescents can be well determined by echocardiography.

Adolescent↗
PubMed2001

Interventional occlusion of congenital vascular malformations with the detachable Cook coil system.

INTRODUCTION: Nonsurgical closure of pathologic vascular communications can be achieved by coil embolization. Different systems used in patients with congenital heart disease (e.g., patent ductus arteriosus) allow controlled release of the devices. However, they are too stiff for coil occlusion of small or tortuous vessels. METHODS AND PATIENTS: The new detachable Cook coil system combines flexibility with a simple release control mechanism. Five children, age 8 days to 10 years, underwent heart catheterization for interventional occlusion of different vascular malformations (two coronary artery fistulas, two aortopulmonary collaterals, and one hemangioma). The diameter of the vessels varied between 1.8 mm and 3.6 mm and the length between 10 mm and 22 mm. RESULTS: Up to four 0.018" soft spiral coils were placed as distally as possible in the feeding vessels. In addition, in two patients, one to three J-shaped coils were placed inside and proximal to spiral coils. Positioning of the coils was controlled easily by radio-opaque markers. Counter-clockwise rotation of the delivery wire provided fast and safe detachment without movement of the detached coils. Control angiograms showed complete occlusion of the vessels within 10 minutes after delivery of coils. CONCLUSION: Interventional closure of vascular malformations can be successfully obtained with the detachable Cook coil system. This system offers safe and controlled placement of coils, and it works rapidly in an uncomplicated manner.

Arteriovenous Malformations↗
PubMed2001

Fast acceleration-encoded magnetic resonance imaging.

Direct acceleration imaging with high spatial resolution was implemented and tested. The well-known principle of phase encoding motion components was applied. Suitable gradient switching provides a signal phase shift proportional to the acceleration perpendicular to the slice in the first scan of the sequences. An additional scan serving as a reference was recorded for compensation of phase effects due to magnetic field inhomogeneities. The first scan compensated for phase shifts from undesired first- and second-order motions; the second scan was completely insensitive to velocity and acceleration in all directions. Advantages of the proposed two-step technique compared to former approaches with Fourier acceleration encoding (with several phase encoding steps) are relatively short echo times and short total measuring times. On the other hand, the new approach does not allow us to assess the velocity or acceleration spectrum simultaneously. The capabilities of the sequences were tested on a modern 1.5 T whole body MR unit providing relatively high gradient amplitudes (25 mT/m) and short rise times (600 micros to maximum amplitude). The results from a mechanical acceleration phantom showed a standard deviation of 0.3 m/s2 in sequences with an acceleration range between -12 and 12 m/s2. This range covers the expected maximum acceleration in the human aorta of 10 m/s2. Further tests were performed on a stenosis phantom with a variable volume flow rate to assess the flow characteristics and possible displacement artifacts of the sequences. Preliminary examinations of volunteers demonstrate the potential applicability of the technique in vivo.

Acceleration↗
PubMed2000

S-100 after correction of congenital heart defects in neonates: is it a reliable marker for cerebral damage?

BACKGROUND: Newborns undergoing cardiac operation may acquire some extent of neuronal damage. An early diagnosis is especially hard regarding neonates. In the past years, S-100 has been widely discussed as a marker revealing perioperative damage to the brain. METHODS: Sequential blood samples from 33 neonates undergoing repair of congenital heart disease were taken perioperatively. Samples of 12 healthy neonates were taken at birth as a control group. The newborns were divided into four groups: cyanotic and acyanotic disease operated on in deep hypothermic circulatory arrest, operation without deep hypothermic cardiac arrest, and operation without extracorporeal circulation. RESULTS: Even in healthy neonates, serum S-100 levels were at 10-fold values compared with adults. On admission, S-100 values in the operative groups were similar. During extracorporeal circulation, levels rose to a certain degree. Cyanotic newborns operated on in deep hypothermic cardiac arrest had significantly higher S-100 levels compared with acyanotic newborns also operated on in deep hypothermic cardiac arrest (p < 0.001). Two newborns who experienced seizures postoperatively had the highest absolute S-100 levels. One child with a poor neurologic outcome but no seizures did not have different values when compared with her group. CONCLUSIONS: In this study, S-100 seemed to be a possible marker for a certain degree of neurologic deficit after cardiac operation in neonates, especially regarding postoperative seizures. The missing peaks of this protein in one newborn with poor neurologic outcome show that it is not possible to exclude damage to the brain with normal postoperative values. These results suggest that the mechanism of cerebral damage and S-100 release into the blood in neonates with a developing central nervous system and blood-brain barrier is not fully understood.

Adult↗
PubMed1998

31P NMR spectroscopy detects metabolic abnormalities in asymptomatic patients with hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) often causes sudden, unexpected death in adolescents and young adults. Alterations in myocardial metabolism are considered to be causes for contractile dysfunction. We examined the question of whether metabolic abnormalities antedate the manifestation of symptoms in patients with HCM. METHODS AND RESULTS: Proton-decoupled 31P NMR spectroscopy of the anterior left ventricular wall of the heart of 14 young, asymptomatic patients with HCM was performed with a 1.5-T whole-body imager. Spectra of the phosphate metabolites were compared with those of normal control subjects. The patients exhibited a significantly reduced (P<0.02) ratio of phosphocreatine (PCr) to ATP of 1.98+/-0.37 (mean+/-SD), compared with 2.46+/-0.53 obtained in 11 normal control subjects. In addition, the group of patients with severe hypertrophy of the interventricular septum (n=8) showed a significantly increased (P<0.05) Pi-to-PCr ratio, with a Pi x 100/PCr of 20.0+/-8.3 versus 9.7+/-7.2 in control subjects. Both abnormalities are similar to those found in ischemic myocardium. This view is also supported by a significantly increased (P<0.01) phosphomonoester (PME)-to-PCr ratio, with a PME x 100/PCr of 20.7+/-11.2 compared with 8.4+/-6.7 in control subjects, indicating altered glucose metabolism. CONCLUSIONS: 31P NMR spectroscopy detects alterations of myocardial metabolism in asymptomatic patients with HCM. These alterations may contribute to the understanding of the pathophysiology and natural history of the disease.

Adolescent↗
PubMed1998

Detection of phosphomonoester signals in proton-decoupled 31P NMR spectra of the myocardium of patients with myocardial hypertrophy.

Proton-decoupled 31P NMR spectroscopy at 1.5 T of the anterior left ventricular myocardium was used to monitor myocardial phosphate metabolism in asymptomatic patients with hypertrophic cardiomyopathy (HCM, n = 14) and aortic stenosis (AS, n = 12). In addition to the well-known phosphorus signals a phosphomonoester (PME) signal was detected at about 6.9 ppm in 7 HCM and 2 AS patients. This signal was not observed in the spectra of normal controls (n = 11). We suggest that in spectra of patients with myocardial hypertrophy the presence of a PME signal reflects alterations in myocardial glucose metabolism.

2,3-Diphosphoglycerate↗