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Biomedical subjects

I Michel-Behnke

Publications and source records attributed to I Michel-Behnke.

At least 19 recordsLinked to original sources
PubMed2006

Pulmonary flow reserve in children with idiopathic pulmonary arterial hypertension: implications for diagnosis and therapy.

AIMS: Endothelial dysfunction is likely to contribute to the pathogenesis of idiopathic Pulmonary Arterial Hypertension (iPAH). We hypothesize that there are different patterns of endothelial cell function, which we studied in 17 children with iPAH. METHODS AND RESULTS: Pulmonary flow reserve was determined by acetylcholine infusion into segmental pulmonary arteries utilizing quantitative angiography and intra-arterial Doppler flow wire. Depending on the reactivity of the pulmonary to systemic arterial pressure ratio to short-term oxygen and intravenous epoprostenol or aerosolized iloprost responders and nonresponders were classified. In 7 responders to oxygen-prostanoid administration the pressure ratio decreased from 0.9 +/- 0.2 to 0.31 +/- 0.11 (p = 0.01), the mean pulmonary flow reserve showed an excessive increase to 3.6 +/- 2.0 (p = 0.01) after infusion of acetylcholine. In 10 non-responders the pressure ratios remained unchanged during oxygen-prostanoid testing. 4 of 5 patients without any effect to acetylcholine died despite long-term epoprostenol treatment. The other 5 nonresponders to oxygen-prostanoid showed an impaired but significant increase of the pulmonary flow reserve of 1.6 +/- 1.1 (p = 0.01). 2 of these patients did not only improve clinically, but regained vascular reactivity by additional therapy with sildenafil. CONCLUSION: Endothelial reactivity in iPAH is either extensive, impaired or absent. Acetylcholine infusion casts a light on the pathogenesis and has implications for therapy.

Acetylcholine↗
PubMed2005

Perioperative management in pediatric heart transplantation.

Peri- and early postoperative mortality significantly influences the probability of survival following heart transplantation in children. Main causes of death early after transplantation are rejection, non specific graft failure and RV failure due to pulmonary hypertension. Optimal therapy of pulmonary hypertension and aggressive use of assist devices as a bridge to recovery will substantially improve survival in the early period after transplantation. Furthermore, the use of marginal donor organs will be more acceptable because transient myocardial insufficiency may recover during extracorporeal life support.

Child↗
PubMed2003

Stenting of the ductus arteriosus and banding of the pulmonary arteries: basis for various surgical strategies in newborns with multiple left heart obstructive lesions.

OBJECTIVE: To present an institutional experience with stent placement in the arterial duct combined with bilateral banding of the pulmonary artery branches as a basis for various surgical strategies in newborns with hypoplastic left heart obstructive lesions. DESIGN: Observational study. SETTING: Paediatric heart centre in a university hospital. PATIENTS: 20 newborns with various forms of left heart obstructive lesions and duct dependent systemic blood flow. INTERVENTIONS: Patients underwent percutaneous ductal stenting and surgical bilateral pulmonary artery banding. Atrial septotomy by balloon dilatation was performed as required, in one premature baby by the transhepatic approach. MAIN OUTCOME MEASURES: Survival; numbers of and reasons for palliative and corrective cardiac surgery. RESULTS: One patient died immediately after percutaneous ductal stenting. One patient died in connection with the surgical approach of bilateral pulmonary banding. Stent and ductal patency were achieved for up to 331 days. Two patients underwent heart transplantation and two patients died on the waiting list. Ten patients had a palliative one stage procedure with reconstruction of the aortic arch and bidirectional cavopulmonary connection at the age of 3.5-6 months. There was one death. One patient is still awaiting this approach. Two patients received biventricular repair. In one, biventricular repair will soon be provided. CONCLUSIONS: Stenting the arterial duct combined with bilateral pulmonary artery banding in newborns with hypoplastic left heart or multiple left heart obstructive lesions allows a broad variation of surgical strategies depending on morphological findings, postnatal clinical conditions, and potential ventricular growth.

Cardiac Catheterization↗
PubMed2000

Safety and efficacy of interventional occlusion of patent ductus arteriosus with detachable coils: a multicentre experience.

UNLABELLED: In order to define the safety and efficacy of Cook detachable coils for interventional closure of patent ductus arteriosus, we performed a retrospective analysis of all patients who underwent cardiac catheterization in seven centres for intended interventional occlusion of patent arterial duct. From January 1995 until March 1998, cardiac catheterization for intended interventional occlusion of patent arterial duct was performed in 317 consecutive children. Successful placement of at least one coil was achieved in 282 children (89%). The mean diameter of the ductus in children treated with Cook detachable coils was 1.65 mm, mean fluoroscopy time was 10.7 min. Occlusion rates were 62% 10 min after the procedure, 82% at the time of discharge, 91% at 4 months and 95% at late follow-up (2 years). In children with a ductus diameter of < or = 2.5 mm the rate of successful coil deployment was 94% with a 98% occlusion rate at late follow-up. Complications occurred in 11 procedures (3.5%) including haemolysis (3 patients), embolization of a coil to the pulmonary artery (7 patients, 2.3%) and inability to release a coil (1 patient). CONCLUSION: In our opinion, Cook detachable coils are safe and effective especially in the treatment of persistent ductus arteriosus with a diameter < or = 2.5 mm. Due to the low costs these coils appear to be superior to other devices in this subgroup of patients.

Adolescent↗
PubMed1999

[Reopening of a persistent left superior vena cava in the early postoperative period following bidirectional cavopulmonary anastomosis--treatment by coil embolization].

Diagnosis of systemic venous drainage is mandatory for patients with congenital heart disease planned for cavopulmonary anastomosis or any Fontan-type palliation. Preexisting venous channels as the persistent left superior vena cava are common in cardiac anomalies and may lead to postoperative deterioration and cyanosis. We describe a 6 month old boy with a complex imbalanced atrioventricular septal defect who developed cyanosis in the very early postoperative period, following bidirectional cavopulmonary anastomosis. It was caused by ineffective lung perfusion due to a reopened persistent left superior vena cava with drainage to the coronary sinus.He underwent coil embolization of the persistent left superior vena cava with retrievable coils and cyanosis improved. Coil embolization is an effective alternative to secondary surgery, especially for hemodynamically compromised patients in the postoperative period.

Angiography↗
PubMed1998

[Heart transplantation in infancy: experiences at the Giessen Pediatric Heart Center].

From June 1988 to December 1996 heart transplantations were performed in 36 newborns and infants below one year of age. Diagnosis were hypoplastic left heart syndrome (n = 26), endocardial fibroelastosis (n = 4), cardiomyopathy (n = 3), and other complex congenital heart defects (n = 3). Mean waiting time for transplantation was 52 days, the mean donor-recipient bodyweight ratio was 1.8. Seven patients (19%) died after transplantation mainly within the first month after transplantation. The cumulative probability of survival is 79% in all patients. The influence of increasing experience is indicated when patients transplanted from 1988-1993 (n = 15) are compared with transplants from 1994-1996 (n = 21). The overall survival in the first group was 50%, whereas patients transplanted from 1994 showed a probability of survival of 92%. The 1-year survival rate in the later group was 100%. In 20 patients a total of 31 rejection episodes were observed. 2 infants died due to rejection. 71% of all rejections occurred during the first month after transplantation. Renal function was slightly impaired one year after transplantation in all patients without tendency for deterioration in the sequel. The somatic development is normal in nearly all infants and the quality of life is excellent. All infants live at home without any restrictions. Two patients, however, suffer from a neurologic deficit. Until now there is no evidence of coronary vascular disease or malignancy. Heart transplantation is in our opinion a reconsiderable alternative in the treatment of complex cardiac disease and cardiomyopathy in infants.

Cause of Death↗
PubMed1998

Superior caval venous syndrome after atrial switch procedure: relief of complete venous obstruction by gradual angioplasty and placement of stents.

Superior caval venous syndrome is one of the late problems known to occur after Mustard repair of complete transposition. Reoperation may leave residual stenosis, and carries substantial risk for the patient. It is now feasible to use intravascular stents to overcome systemic venous baffle obstructions, and such an approach is probably more effective. The purpose of our study therefore, was to assess immediate and medium term results of inserting stents subsequent to gradual balloon enlargement of acquired atresia of the intraatrial baffle in patients who had undergone an atrial switch operation. We investigated five patients with complete obstruction of the superior caval venous pathway at perforation of the atretic segment was achieved using a guide wire technique. The procedure was successful in all patients. Gradual angioplasty was performed and intravascular stents were implanted. The pressure in the superior caval vein dropped to normal values, symptoms improved, and the patency of the newly created venoatrial communication was proven at mid-term follow-up. Thus critical obstructions at the superior caval venous pathway after the Mustard procedure can be reopened by interventional catheterization. Implantation of balloon-expandable intravascular stents is safe and effective in the acute relief of the obstructions, but careful long-term follow-up is mandatory.

Adolescent↗
PubMed1998

Percutaneous closure of secundum atrial septal defect with a new self centering device ("angel wings").

OBJECTIVE: To investigate the safety, efficacy, and clinical application of a new self centering device ("angel wings") for closure of secundum atrial septal defects (ASD II) and persistent foramen ovale in all age groups. DESIGN: Multicentre, prospective, nonrandomised study. PATIENTS INCLUSION CRITERIA: defects with an occlusive diameter of < or = 20 mm and a surrounding rim of > 4 mm; body weight > 10 kg; and an indication for surgical closure of secundum atrial septal defect. Additionally, there were compassionate indications for closure in patients with persistent foramen ovale. INTERVENTIONS: Defects were closed by a transcatheter device consisting of two square frames made of superelastic nitinol wire. The frames are covered by elastic polyester fabric, which is sewn together at a central circle. All procedures, except for three interventions that were carried out under sedation, were performed under general anaesthesia using transoesophageal echocardiography and fluoroscopy to monitor intervention. RESULTS: Closure was attempted in 75 (71%) of 105 patients. An ASD II was present in 35 children and 15 adults. A persistent foramen ovale was present in 25 adults with suspected paradoxical embolism. Transcatheter closure was unsuccessful in three children and crossover to surgery was required. Residual shunts were found in 20 patients (27%) immediately after the procedure. A transient atrioventricular third degree block occurred in three patients (4%) and the right atrial disk was not fully deployed in three. A minor shunt (< 3 mm) was present in only three (4%) of 72 patients during follow up of 1-17 months. Blood clots on the right atrial disks in two patients (one required lysis) were seen during follow up transoesophageal echocardiography. Serious complications demanding surgical removal of the device occurred in three patients. One patient had haemopericardial tamponade because of an aortic lesion. Left atrial thrombus formation due to an unfolded right atrial disk was found in a second patient and dislodgement of the left atrial disk resulted in a large residual shunt in a third. CONCLUSIONS: Percutaneous closure of a central ASD with a diameter < or = 20 mm in paediatric and adult patients is feasible and effective with this new device. It is a promising alternative to surgical closure. Modifications of the design, however, seem to be mandatory as 4% of patients developed serious complications.

Adolescent↗
PubMed1997

Microdeletion 22q11 in complex cardiovascular malformations.

Besides DiGeorge, velocardiofacial and conotruncal anomaly face syndromes, some of the isolated congenital heart diseases have also been associated with a chromosomal deletion in 22q11. These disease entities, which had originally been considered to have a different genetic background, are now included in the CATCH-22 microdeletion complex. CATCH 22 is an acronym for cardiac defect, abnormal facies, thymic hypoplasia or aplasia and T-cell deficiency, cleft palate, hypoparathyroidism, and hypocalcemia. In the present study, we focused on the complex cardiovascular defects (CCVD) and screened 40 patients for a microdeletion of 22q11 by fluorescence in situ hybridization using the D22S75 DNA probe and for associated CATCH features. The patients were from genetic counseling (n = 15) or fetopathology (n = 3) of the Clinical Genetics Department in Marburg and from the Pediatric Cardiology Department (n = 22) in Mainz. Monosomy 22q11 was detected in 9 cases (= 22.5%). Familial transmission with one mildly affected parent and one affected sib each was proven in two cases. The CCVDs comprised complex conotruncal defects such as tetralogy of Fallot, double outlet right ventricle, transposition of great arteries and truncus arteriosus communis, or anomalies of the derivatives of the branchial arch arteries in association with a ventricular septal defect, including one case of atresia of the ductus arteriosus with pulmonary artery aneurysm and resulting in fetal hydrops. All 13 patients with a deletion of 22q11 showed at least one additional CATCH symptom. Most consistently, facial dysmorphy was apparent (92%), while hypocalcemia, mostly at threshold values, was present in 62% and thymic hypoplasia including borderline low T-lymphocyte numbers was observed in 41%. None of the patients presented with a cleft palate. A high intrafamilial variability in expression was also evident with respect to the CCVD. Our findings indicate that seemingly isolated complex cardiovascular defects associated with a 22q11 microdeletion most probably do not represent a distinct subgroup within the CATCH-22 complex but are syndromal in nature with extracardiac features that are often overlooked.

Adolescent↗
PubMed1996

Gradual angioplasty and stent implantation to treat complete superior vena cava occlusion after Mustard procedure.

A 16-year-old male was admitted with complete occlusion of the superior vena cava pathway 14 years after Mustard procedure for transposition of the great arteries. From a left subclavian vein approach, the atretic vein segment was perforated using a straight guidewire, and was followed by sequential balloon dilation. Implantation of a 30 mm Palmaz-stent through a femoral vein approach resulted in a widely patent channel of the vena cava superior into the systemic venous atrium.

Adolescent↗
PubMed1996

[Intravascular stents for treatment of systemic venous obstructions].

Two young adults, 16 and 18 years of age were admitted with complete occlusion of the superior vena cava pathway following previous Mustard procedure. In both patients, perforation of complete occluded vein segment using a straight guidewire and subsequent sequential enlargement by balloon dilation were successfully performed by a left subclavian vein approach. Implantation of a 30 mm Palmaz-stent resulted in a widely patent channel of the vena cava superior into the systemic venous atrium. In short-term follow-up of 3 months both stents remained patent. Repeat dilation of the stents was performed after 3 months. A third patient with systemic venous obstruction was a 3-year old child who suffered low cardiac output following modified Fontan operation caused by a narrowing of the superior vena cava to right pulmonary artery connection and stenosis of distal left pulmonary artery. The severe hemodynamic problem was resolved by implantation of Palmaz-stents in the two separate obstructions. At recatheterization 6 months later, both stents were patent without any residual pressure gradient.

Adolescent↗
PubMed1995

Transcatheter radiofrequency perforation and stent implantation for palliation of pulmonary atresia in a 3060-g infant.

In a 3060-g infant with fibromuscular pulmonary atresia an open right ventricular outflow tract was created by means of interventional cardiological methods. Following two inadvertent perforations without sequelae or clinical symptoms, radiofrequency perforation and subsequent balloon dilatation were successfully performed. The implantation of a Palmaz iliac stent led to a predictable communication between the right ventricle and pulmonary artery.

Cardiac Catheterization↗
PubMed1995

Mitral and aortic regurgitation in 84 patients with mucopolysaccharidoses.

UNLABELLED: In echocardiographic and necropsy studies nodular thickening of the mitral valve and, less frequently, of the aortic valve has been found in 60%-90% of patients with mucopolysaccharidoses (MPS). Little is known about the haemodynamic consequences of these morphological changes. In this study 84 unselected patients with different enzymatically proven MPS and 84 age and sex matched, healthy persons were studied prospectively by colour Doppler flow mapping. The patients' age ranged from 1 to 47 years (median 8.1 years). Mitral and aortic regurgitation were defined as a holosystolic or holodiastolic jet originating from the valve into the left atrium or the left ventricular outflow tract, respectively, with peak velocities exceeding 2.5 m/s. Of the 84 patients with satisfactory studies, mitral regurgitation was detected in 64.3% and aortic regurgitation in 40.5%, respectively. Regurgitation was severe in 4.8% of mitral valves and 8.3% of aortic valves. The frequency of aortic and/or mitral regurgitation was 75% in all patients, 89% in MPS I, 94% in MPS II, 66% in MPS III, 33% in MPS IV, and 100% in MPS VI. Combined mitral and aortic regurgitation was present in 29% of our patients. None of the control persons showed mitral or aortic regurgitation. CONCLUSION: Aortic and mitral regurgitation are more frequent in patients with MPS than previously thought and that therefore these patients should have regular colour Doppler flow mapping and antibiotic prophylaxis when required.

Adolescent↗
PubMed1995

Norepinephrine, enoximone, and nitric oxide for treatment of myocardial stunning and pulmonary hypertension in a newborn with diaphragmatic hernia.

A newborn with right diaphragmatic hernia suffered myocardial stunning and suprasystemic pulmonary hypertension secondary to postpartal asphyxia. In addition to conventional therapy, norepinephrine, enoximone, and inhalational nitric oxide were successfully used. Norepinephrine improved myocardial perfusion pressure; the addition of enoximone, a phosphodiesterase-inhibitor, to beta-adrenergic agents increased cardiac performance. with decreasing concentrations of inhalational nitric oxide, severe pulmonary hypertension resolved after a few days, suggesting that transient endothelial dysfunction was partially responsible for pulmonary vasoconstriction in the newborn with congenital diaphragmatic hernia.

Enoximone↗
PubMed1990

Distribution of type I and type II collagen gene expression during the development of human long bones.

The temporal and spatial gene expression of collagen type I and type II during the development of the human long bones was studied by the technique of in situ hybridization covering the period from the cartilagenous bone anlage to the formation of a regular growth plate in the newborn. Analysis of the early stages around the seventh week of gestation revealed for type II collagen a strong hybridization signal limited to the chondrogenic tissue. The surrounding connective tissue and the perichondrium showed weak type I collagen expression, while the zones of desmal ossification like the clavicle gave a strong signal. Beginning with the eighth week of gestation, type I collagen mRNA was detectable in newly formed osteoblasts at the diaphysis and appeared along with the formation bone marrow, in the areas of enchondral ossification. Parallel to the development of the different zones of cartilage differentiation, a specific pattern of type II expression could be observed: type II was mainly found in the chondrocytes of the hypertrophic zone and to a lesser degree in the zone of proliferation, while the resting zone and the zone of provisional calcification showed little activity. This segregation of type II expression was most pronounced in the early stages of cartilage calcification and in the growth plate of the newborn.

Bone Development↗