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Biomedical subjects

P Bonhoeffer

Publications and source records attributed to P Bonhoeffer.

At least 19 recordsLinked to original sources
PubMed2006

[Development and evaluation of a prosthetic valved conduit dilated by percutaneous approach: experimental study in the lamb].

This study was undertaken to develop a dilated valved conduit for reconstruction of the right ventricular outflow tract in the animal. The conduits were made by sewing a valved tube (Medtronic Inc) inside a vascular stent (Numed Inc). After preparation, they were inserted surgically in five lambs. The conduits were then dilated 6 weeks and 3 months after their implantation. Before sacrificing the animals at 3 months, a 22 mm valved stent was implanted percutaneously inside the surgical conduits. One animal died suddenly due to kinking of the conduit. Balloon dilatation was performed in the surviving animals. The first dilatation only had a modest impact on valvular function but it was much aggravated after the second dilatation. A valved stent was successfully inserted percutaneously. At sacrifice, all the conduits were completely engulfed in an intense fibrosis. In conclusion, a valved biological conduit for reconstruction of the right ventricular ejection tract has been developed and can be dilated sequentially to follow growth. The new product could have an important role to play in the management of congenital malformations involving the right ventricular outflow tract.

Animals↗
PubMed2005

Role of atrial septostomy in the treatment of children with pulmonary arterial hypertension.

OBJECTIVES: To assess in retrospect the safety and effectiveness of atrial septostomy in children with severe pulmonary arterial hypertension without an intracardiac communication. METHODS: 20 patients were reviewed retrospectively, 19 with idiopathic pulmonary arterial hypertension. The mean age at septostomy was 8.4 years (range 3 months to 17 years). Graded balloon septostomy alone was carried out in eight patients, a blade septostomy was done in two, a blade septostomy plus graded balloon septostomy was done in three, and a fenestrated device was inserted in seven. RESULTS: There were no fatalities. Four children suffered complications during the procedure. None had further syncope and all improved symptomatically with a significant (p < 0.01) decrease in World Health Organization functional class (mean shift -0.6) and a significant improvement in the semiquantitative echocardiographic assessment of right ventricular function (p < 0.03). The mean oxygen saturation decreased by 7.8 percentage points. The atrial communication closed in two children, necessitating a repeat procedure. After a mean follow up of 2.1 years (range one month to 6.7 years), 18 of 20 children are still alive. CONCLUSION: Atrial septostomy improved symptoms and quality of life in a group of children deteriorating with severe pulmonary arterial hypertension. This procedure is to be recommended for severely symptomatic children, before they become critically ill. Fenestrated devices may help ensure indefinite patency of the atrial communication.

Adolescent↗
PubMed2004

[Multicentre study of percutaneous closure of interventricular muscular defects with the aid of an Amplatzer duct occluder prosthesis].

Percutaneous closure of interventricular defects is an alternative or adjunct to surgery with the disadvantage of a sometimes prolonged and difficult catheterisation only during which the choice of prosthesis can be determined. Despite the existence of an occlusion prosthesis, the Amplatzer Septal Defect Occluder, specifically conceived for this purpose, an arterial canal occlusion prosthesis such as the Amplatzer Duct Occluder is sometimes better suited for the occlusion of certain interventricular defects. Since 1999, 11 Amplatzer Duct Occluders were used for the closure of interventricular muscular defects, during 10 catheterisations in 9 patients with a median age of 2.5 (0.1 to 43.9) years. In 5 cases there were residual septal defects after failure of initial surgery. 10 were successful with prostheses of 6/4 mm to 12/10 mm while in one patient the interventricular communication had to be closed surgically because the 14/12 mm prosthesis could not be positioned due to a tortuous introduction route. The only complication was a pericardial effusion requiring surgical drainage in one infant. After a median follow up of 2.1 (0.3 to 4.2) years, all of the patients had a satisfactory functional status, with minimal residual shunt on echocardiography in 2 cases. The Amplatzer Duct Occluder therefore seems better adapted for the closure of post-operative residual interventricular communications, with a thickened interventricular septum or even when the tricuspid valve is very close to the right ventricular side of the orifice.

Adolescent↗
PubMed2003

Percutaneous implantation of pulmonary valves.

Percutaneous implantation of valves is evolving as the most exciting innovation in transcatheter therapeutics. Valve repairs and replacements form an important indication of re-operations after congenital heart operations. Right ventricular outflow tract surgery is common after repair of conditions such as pulmonary atresia with Tetralogy of Fallot, common arterial trunk and Rastelli operation for transposition of great arteries, ventricular septal defect with pulmonary stenosis. Conduit survival is improving, nevertheless, re-operations are common. Although the re-operations can be performed at low risk, they still involve morbidity and mortality. Percutaneous implantation of valves is emerging as an alternative option for these group of patients. Our experience in percutaneous implantation of pulmonary valves has yielded encouraging results. For incompetence, the results are excellent. Evolving technology is making it applicable in wider clinical situations. Similar technology could also be applied to implantation of valves in the aortic position.

Adolescent↗
PubMed2003

Percutaneous transvenous mitral commissurotomy in juvenile mitral stenosis.

OBJECTIVE: To determine the efficacy and safety of percutaneous transvenous mitral commissurotomy (PTMC), using multi-track double balloon technique in juvenile mitral stenosis. DESIGN: Open non-randomised intervention. SETTING: Cardiac catheterisation laboratories of The Mater Hospital, The Nairobi Hospital and Kenyatta National Hospital from 1996 to 2001. PATIENTS: Forty five consecutive patients aged less than 21 years with severe pure mitral stenosis and suitable mitral valve apparatus (leaflets, chordae and papillary muscles) for successful commissurotomy. INTERVENTION: Percutaneous transvenous mitral commissurotomy under local anaesthesia. Standard left and right heart catheterisation for mitral valve disease. Trans-septal left atrial entry using standard septal puncture technique and left ventricular position secured by super-stiff guide-wire. Double-balloon mitral valvotomy on single guide-wire using multi-track balloon catheters. MAIN OUTCOME MEASURES: Mitral valve area, left atrial pressures, mitral regurgitation grade, NYHA functional class. RESULTS: Mitral valve area increased from 0.6 +/- 0.19 cm2 to 1.9 +/- 0.19 cm2 (p<0.001), left atrial pressures from 30.5 +/- 3.9 mmHg to 11.5 +/- 3.8 mmHg (p<0.001). Most patients NYHA functional class immediately improved from class III-IV to class I-II. There was no significant changes in grades of mitral regurgitation or significant complications related to the procedure. CONCLUSIONS: PTMC in juvenile mitral stenosis using the multi-track technique is safe and effective yielding satisfactory immediate results.

Adolescent↗
PubMed2003

[Percutaneous pulmonary valve replacement: towards a modification of the prosthesis].

Percutaneous pulmonary valve replacement has recently been introduced as an alternative to surgery, pushing back the frontiers of interventional catheterisation. The authors report their experience in this field and focus on the complications of the method. From September 2000 to November 2002, 14 patients with a failing artificial pulmonary outflow tract were included in this protocol of clinical research. The authors attempted pulmonary implantation of a bovine jugular vein valve fitted in a vascular stent under general anaesthesia. The implantation was possible in all patients. Three had dynamic obstruction due to the implanted valve. This was due to infiltration of blood between the valve and the stent. The problem was resolved by: implanting a second valve in one patient: redialating the valve stent in two other patients. However, the last patient had to be reoperated 7 weeks after the implantation because of recurrence of the obstruction. One valve had to be explanted one year after implantation because of severe infectious endocarditis after unprotected dental treatment. Two patients experienced fracture of the stent but without valve dysfunction. Despite these complications, the clinical state of all patients improved during follow-up. The authors conclude that non-surgical pulmonary valve replacement is feasible, thereby increasing the therapeutic arsenal of interventional catheterisation. Simple modifications should result in fewer problems of dynamic obstruction and stent fracture, and lead to proposing this technique for native pulmonary outflow tracts.

Adolescent↗
PubMed2002

Percutaneous implantation of a valve in the descending aorta in lambs.

AIMS: We assessed the feasibility of percutaneous implantation of a valve in the descending aorta and its function in systemic pressures. METHODS AND RESULTS: A biological valve harvested from a bovine jugular vein was sutured into a stent. After the creation of aortic insufficiency, the valved stent was percutaneously implanted into eight lambs divided into two groups depending on the severity of the insufficiency created. Haemodynamic and angiographic evaluations were carried out. Anatomical evaluation was finally performed. Aortic insufficiency was created: four lambs had mild insufficiency and four massive insufficiency. A valve was successfully implanted in all and were functioning perfectly in the early follow-up. Despite this competence, animals with massive insufficiency died within 24 h following implantation. None of the animals with mild insufficiency died. The valve was functioning perfectly in the first 2 months following the implantation, but became incompetent after spontaneous healing of the wound of the aortic valve. CONCLUSION: Percutaneously implanted valves in the descending aorta of lambs with aortic insufficiency function well in the early follow-up. This technique might become an interesting alternative to the standard approach in patients in whom perioperative risk is high.

Animals↗
PubMed2002

Assessment of muscular ventricular septal defect closure by transcatheter or surgical approach: a three-dimensional echocardiographic study.

AIMS: Previous classification of muscular ventricular septal defects (VSDs) visualized on two-dimensional echocardiography relied on artificial divisions of the septum. New visualization of the ventricular septum integrating the third dimension would facilitate communication between cardiologists and surgeons. The objectives of this study were (1) to assess in patients with muscular ventricular septal defects the accuracy of left ventricular three-dimensional echocardiographic reconstructions in demonstrating the position, the size and the tissue rims of the defects; (2) to compare findings by three-dimensional echocardiography with those obtained by surgical and transcatheter approaches. METHODS AND RESULTS: Twenty-six patients, aged from one month to 40 years, with muscular ventricular septal defects underwent three-dimensional echocardiographic study. From the left ventricular three-dimensional echocardiographic reconstructions, the localization, the maximal diameter and the tissue rim of the defect were analysed and compared with surgical or transcatheter findings. Optimal three-dimensional echocardiographic reconstructions were obtained in 22 patients. Nineteen had a single muscular ventricular septal defect and three had multiple muscular ventricular septal defects. The muscular ventricular septal defect localizations were the inlet septum in three, the outlet septum in three, the mid-muscular septum in 14 and the apex in eighth. In 10 patients who underwent surgical closure, the correlation between three-dimensional echocardiography and surgery for muscular ventricular septal defect maximal diameter was y=0 x 95 x +0.13 (r=0.98; P<0.001). The agreement between three-dimensional echocardiographic and intraoperative findings on muscular ventricular septal defect localization were complete. In five patients who underwent transcatheter closure, the mean difference between three-dimensional echocardiographic maximal diameter and stretched diameter was 1 x 8+/-0 x 5 mm. CONCLUSION: The three-dimensional echocardiographic left ventricular views provide a new and easily communicated visualization of various muscular ventricular septal defects. Such new imaging should contribute to the surgical and transcatheter treatments of muscular ventricular septal defects.

Adolescent↗
PubMed2002

[Percutaneous closure of a paravalvular mitral regurgitation with Amplatzer and coil prostheses].

The authors report a case of percutaneous closure of paravalvular mitral regurgitation in a 9 year old child. This patient had complete atrioventricular canal with levo-isomerism completely repaired with replacement of the left atrioventricular valve by a mechanical prosthesis. One year after an episode of infectious endocarditis, the patient was readmitted because of jaundice due to haemolysis attributed to paravalvular mitral regurgitation. Transoesophageal echocardiography demonstrated a crescent-shaped dehiscence of the prosthesis opposite the left atrial appendage associated with a small paraseptal regurgitation. First of all, a 6 mm Amplatzer Septal Occluder and a 5 x 5 coil were introduced by retrograde catheterisation to treat the regurgitation due to the valve dehiscence. This procedure was completed 3 months later by the implantation of a second 8 mm Amplatzer prosthesis for persistent haemolysis. Closure of the paraseptal regurgitation resulted in a reduction of the patient's transfusional requirements.

Child↗
PubMed2001

Results of the arterial switch operation in neonates with transposed great arteries.

BACKGROUND: The arterial switch operation is judged the best palliative operation for neonates with transposed great arteries. We aimed to assess the value of analysing a large series of unselected cases by this technically demanding operation and formulate a realistic prognosis. METHODS: We reviewed all 432 neonates (mean age at operation 7 days, mean weight 3.25 kg) who underwent an arterial switch operation between 1987 and 1999. Follow-up (mean time: 4.9 years) was complete in 412 patients. FINDINGS: Survival probability and freedom from reoperation was 94% and 78% at 10 years, respectively. 26 patients died, 16 because of myocardial ischaemia. Risk factors for death included early experience, low weight, associated cardiovascular malformations (especially hypoplasia of the right ventricle or aortic arch), and difficult patterns of coronary arteries. The risk of the coronary artery pattern was greatly reduced in those who had recent operations. At last follow-up, 90% of patients had normal life without treatment, and 94% a normal heart function on echocardiography. INTERPRETATION: The arterial switch operation in neonates achieves excellent results mid-term. Obstruction of the translocated coronary arteries is responsible for most deaths and a substantial number of reoperations. Although confirmation is needed, these results allow anticipation of a favourable long-term prognosis.

Disease-Free Survival↗
PubMed2001

Selective coronary angiography in patients younger than 1 year of age.

Precise assessment of coronary artery anatomy is needed in congenital coronary malformations and acquired coronary obstruction in children. The aim of the study was to describe our experience of selective coronary angiography (SCA) in newborns and infants. One hundred and three patients younger than 1 year of age underwent SCA. Indications were preoperative screening for coronary artery lesions or anomalous pattern (41 patients), signs of myocardial ischemia (43 patients), surgical difficulties during the reimplantation of the coronary arteries without signs of ischemia (15 patients), and other indications (4 patients). Success rate of selective injection was 100% with no significant complication. In the presence of clinical suspicion of myocardial ischemia, abnormalities of coronary artery pattern was found in 17 of 43 patients. Precious information for the surgical management was obtained in 13 of 41 patients. SCA can be performed safely even in newborns and small infants. Skills in catheterization and knowledge about the coronary artery anatomy are needed to perform SCA.

Coronary Angiography↗
PubMed2001

A new percutaneously adjustable, thoracoscopically implantable, pulmonary artery banding: an experimental study.

BACKGROUND: In patients who undergo left ventricular retraining, multiple reoperations are often necessary to adjust the pulmonary artery banding. The availability of a percutaneously adjustable band would be very useful. METHODS: Ten lambs (10 to 25 kg) underwent pulmonary artery banding using a new device, 7 by thoracotomy and 3 by thoracoscopy. The possibility of percutaneously adjusting the band was evaluated immediately after operation in 10 animals and at 3 months in 8 animals. RESULTS: One death occurred on the day of the procedure from displacement of the device and another death was from infection. Immediate hemodynamic studies proved the feasibility of increasing right ventricular afterload in a precise and reversible way. After 3 months the band could still be precisely loosened or tightened in all but 1 animal. Autopsy revealed that all the devices were in the correct position and no fibrosis or adhesions were present around the devices, and there was no residual stenosis noted on the pulmonary artery. CONCLUSIONS: This new device may be a valuable alternative to the repeated pulmonary artery banding needed for ventricular preparation.

Animals↗
PubMed2001

Assessment of the geometric profile of the Amplatzer and Cardioseal septal occluders by three dimensional echocardiography.

OBJECTIVE: To apply three dimensional echocardiography to describe the geometric profile of the Amplatzer and Cardioseal occluders after deployment for closure of atrial septal defect. METHODS: 20 patients (mean (SD) age, 14 (5) years) were enrolled for transcatheter closure of a secundum atrial septal defect with the Amplatzer occluder (10) or with the Cardioseal occluder (10). The two populations were matched for the stretched diameter of the defect (mean 18 (6) mm). The profile of the two occluders was examined. RESULTS: Transoesophageal echocardiography did not show any residual shunts after Amplatzer occluder deployment, whereas three patients had a small residual leak after Cardioseal deployment. One patient had transient atrioventricular block with the Amplatzer device. The mean surface area of the Amplatzer occluder was 6.9 (2) cm(2), and that of the Cardioseal device 5.4 (3) cm(2) (p = 0.03). The mean volume of the Amplatzer occluder was 9.2 (1) cm(3), while that of the Cardioseal occluder was 3.5 (1) cm(3) (p < 0.0001). From the three dimensional views, the Cardioseal occluder looked like a flat square after deployment whereas the Amplatzer occluder took up a ball shape in the atrial cavity. CONCLUSIONS: Three dimensional views by multiplane transoesophageal echocardiography allow a realistic in vivo description of atrial septal occluders. The Amplatzer occluder, with its high geometric profile, allows complete closure of large atrial septal defects but with some risk of mechanical complications. Use of the Cardioseal device, with its small surface coverage and high residual shunt rate, should be limited to transcatheter closure of a patent foramen ovale or small atrial septal defects.

Adolescent↗