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Biomedical subjects

M Tynan

Publications and source records attributed to M Tynan.

At least 55 records · Page 3Linked to original sources
PubMed1993

Interventional catheterization in congenital heart disease.

Balloon dilation is now an established treatment for many congenital heart defects. Recent papers deal with the extension of this approach to more complex anomalies, such as tetralogy of Fallot and transposition of the great arteries; the results are variable. Another area of investigation is balloon valvoplasty in more contentious settings, such as neonatal aortic stenosis. The catheter method appears to be as effective as surgery in these cases. Attention has also been directed to the determinants of success or failure in, for example, aortic recoarctation. Here, as in aortic stenosis, basic anatomy plays an important role. Catheter closure procedures also figure in the literature. Closure of persistent ductus now appears to be established everywhere except in the United States. Also of interest are early reports of the "button device" for closure of atrial septal defects. The use of stents appears to offer effective treatment for peripheral pulmonary stenosis, a condition with disappointing results from surgery and balloon angioplasty. Stents may also offer an alternative method for long-term maintenance of duct patency. Catheter interventions now constitute a major part of the work of pediatric cardiologists, and the present status has been summarized in the past year.

Angioplasty, Balloon↗
PubMed1993

Radiofrequency-assisted balloon dilatation in patients with pulmonary valve atresia and an intact ventricular septum.

OBJECTIVE: To investigate the efficacy and safety of transcatheter radiofrequency-assisted valve dilatation for infants with pulmonary valve atresia and intact ventricular septum as an alternative to the use of laser heated wires. DESIGN: Prospective clinical study. SETTING: Three paediatric cardiology centres. PATIENTS: Four children (aged 5-101 days, weight 2.8 kg) with pulmonary valve atresia and intact ventricular septum underwent percutaneous radiofrequency-assisted valve dilatation. METHODS: After delineating the atretic valve by angiography, 0.020 inch or 0.018 inch radiofrequency wires were used to perforate the atretic valve. The valve was then dilated with conventional balloon dilatation catheters up to the valve annulus diameter. RESULTS: In all four cases the radiofrequency wire perforated the atretic pulmonary valve and balloon dilatation was successful. In one patient the radiofrequency wire also passed through the anterior wall of the pulmonary artery causing tamponade which required surgical repair shortly afterwards. This patient died from sepsis six days later. One patient died three weeks after the procedure from septicaemia and a paradoxical coronary embolus. Two patients were discharged after 4 and 14 days respectively. CONCLUSIONS: Radiofrequency-assisted valve dilatation is a promising alternative to the recently developed laser wire technique. The major advantages are a reduction in cost and improved safety for the staff performing the procedure.

Balloon Occlusion↗
PubMed1993

Use of a second transcatheter Rashkind arterial duct occluder for persistent flow after implantation of the first device: indications and results.

OBJECTIVE: To assess the efficacy, feasibility, and most appropriate timing of the implantation of a second Rashkind arterial duct occluder because of persistent flow after the first device. DESIGN: A prospective serial Doppler study of patients after the insertion of a Rashkind arterial duct occluder including a subgroup in whom a second device was implanted. SETTING: A tertiary referral centre for congenital heart disease. PATIENTS: 144 patients aged 7 months to 67 years (median 3.38 years) who underwent transcatheter occlusion of patent arterial duct, 20 of whom had attempted implantation of a second device. INTERVENTIONS: Implantation of a second device alongside the first was attempted in 20 of the patients with persistent residual flow. MAIN OUTCOME MEASURES: Successful implantation of a second device, the incidence of complications, and the achievement of complete occlusion on follow up Doppler echocardiography. The time to complete occlusion in the whole group and factors predictive of persistent leak were also analysed. RESULTS: Second devices were successfully implanted in 19 of 20 first attempts and in the remaining patient at the second attempt. Complete occlusion was found in 19 patients at a mean follow up of eight months. The complications included fracture of a guidewire requiring femoral arteriotomy for its removal in one patient and embolisation of a device in another. With a single device, persistence of residual flow six months after implantation and malposition of the device on the aortogram after implantation were predictive of continuing residual patency. CONCLUSIONS: Implantation of a second device is safe, feasible, and effective and should be considered when residual flow persists beyond six months, or if malposition of the first device causes complications such as haemolysis.

Adolescent↗
PubMed1993

Technique of percutaneous laser-assisted valve dilatation for valvar atresia in congenital heart disease.

OBJECTIVE: To investigate the efficacy and safety of transcatheter laser-assisted valve dilatation for atretic valves in children with congenital heart disease. DESIGN: Prospective clinical study. SETTING: Supraregional paediatric cardiology centre. SUBJECTS: Eleven children (aged 1 day-11 years; weight 2.1-35.7 kg) with atresia of pulmonary (10) or tricuspid (one) valve underwent attempted laser-assisted valve dilatation as part of the staged treatment of their cyanotic heart disease. INTERVENTION: After delineating the atretic valve by angiography and/or echocardiography a 0.018 inch "hot tip" laser wire was used to perforate the atretic valve. Subsequently the valve was dilated with conventional balloon dilatation catheters up to the valve annulus diameter. RESULTS: Laser-assisted valve dilatation was successfully accomplished in nine children. In two neonates with pulmonary valve atresia, intact ventricular septum, and coexistent infundibular atresia the procedure resulted in cardiac tamponade: one died immediately and one later at surgery. During a follow up of 1-17 months (mean 11) two infants with pulmonary valve atresia and intact ventricular septum died (one with congestive cardiac failure). The remainder are either well palliated and do not require further procedures (three), or are awaiting further transcatheter or surgical procedures because of associated defects (four). CONCLUSIONS: Laser-assisted valve dilatation is a promising adjunct to surgery in this high risk group of patients. It may avoid surgery in some patients, and may reduce the number of surgical procedures in those requiring staged operations.

Balloon Occlusion↗
PubMed1992

Determinants of hemodynamic results of balloon dilation of aortic recoarctation.

Between October 1982 and May 1990, balloon dilation of aortic recoarctation was attempted in 27 patients. In 1 case dilation was not performed owing to suspected aortic perforation. The remaining 26 patients had 30 procedures. The age at the first dilation ranged between 2.6 months and 18.3 years. After dilation, systolic gradient decreased from 49 +/- 17 mm Hg to 20 +/- 17 mm Hg (p less than 0.001). A reduction of gradient to less than or equal to 20 mm Hg occurred after the first dilation in 17 of 26 (65%) patients. Residual gradients between 25 and 80 mm Hg were present in the remaining 9 patients. During follow-up of 2 months to 6.7 years, 5 of 17 patients with a good initial result developed further recoarctation (2 had successful redilation, 2 had reoperation, and 1 is awaiting repeat dilation). Of 9 patients with gradients greater than 20 mm Hg after the first dilation, 1 had successful redilation and 3 had reoperation. The remaining 5 patients are being managed conservatively. 2 patients developed aneurysms after dilation (1 immediately and the other at 2 months). In all, 15 patients (58%) had a good, and 11 (42%) a poor late hemodynamic result. Aortic diameters at different levels of the aortic arch and at the reconstructed isthmus (normalized to the aorta at the level of the diaphragm) were significantly higher in the group with a good late result than in that with a poor one. Balloon/aortic diameter ratio at diaphragm level also had a significant influence on the late results.

Adolescent↗
PubMed1992

Countercurrent aortography: an alternative to cardiac catheterization in infancy.

Countercurrent aortography via a peripheral artery was used to clarify the aortic arch anatomy in 25 infants in whom cross-sectional and Doppler evaluation was inconclusive. Ages ranged from 3 days to 11 months (median 9 days), and 80% were neonates. The suspected diagnosis was aortic coarctation in 21 infants, interrupted aortic arch in two, recoarctation in one, and vascular ring in one. A countercurrent aortogram provided adequate diagnostic information in 24 infants. A diagnosis of coarctation was confirmed in 15, interruption of the aortic arch in two, and vascular ring in one. In six infants countercurrent aortography excluded the presence of anomalies of the aortic arch. In only one infant, who had an anomalous origin of the right subclavian artery from the descending aorta, did this technique fail to provide adequate information. The only complication observed was transient ischemia of the arm in one patient. Countercurrent aortography is a minimally invasive procedure that can provide adequate angiographic information without the need for cardiac catheterization in patients with inconclusive echocardiographic evaluation. Injection into a right upper limb artery is preferred, because it gives better opacification of the ascending and transverse aortic arch than injection into a left one.

Aorta, Thoracic↗
PubMed1992

Laser-assisted tricuspid valve balloon dilation for acquired tricuspid valve atresia.

Acquired pulmonary valve atresia is a well-recognized but uncommon complication of surgical systemic-to-pulmonary artery shunts in patients with tetralogy of Fallot. Acquired atresia of the tricuspid valve, however, has not been reported previously. This complication developed in a 3-year-old girl, with pulmonary atresia and an intact ventricular septum, after a Blalock-Taussig shunt and right ventricular outflow tract reconstruction. Percutaneous transcatheter laser-assisted balloon dilation re-established antegrade flow across the tricuspid valve.

Catheterization↗
PubMed1992

Magnetic resonance imaging of hearts with atrioventricular valve atresia or double inlet ventricle.

OBJECTIVE: To investigate the effectiveness and limitations of magnetic resonance imaging in defining cardiac anatomy in patients with double inlet ventricle or atrioventricular valve atresia. DESIGN: Magnetic resonance images were reviewed retrospectively without reference to other morphological data. SETTING: A tertiary referral centre for paediatric cardiology. PATIENTS: 18 patients (aged 8 days to 27 years) with a suspected univentricular atrioventricular connection. METHODS: Imaging by a 1.5 T whole body magnetic resonance system with imaging planes adjusted to individual patient anatomy to best define the cardiac morphology. A complete sequential diagnosis obtained from an independent interpretation of the images was compared with the diagnosis obtained from cross sectional echocardiography and angiocardiography. RESULTS: There was substantial accord between the diagnosis from magnetic resonance alone and that from other methods. In the six instances where there was not accord the magnetic resonance diagnosis was considered to be correct in two cases and incorrect in three cases. In the remaining case no consensus could be reached. In eight patients magnetic resonance imaging provided anatomical information additional to that from other methods. The strengths of magnetic resonance were in imaging the pulmonary arteries and their abnormalities and identifying juxtaposed atrial appendanges but there were some deficiencies in identifying Blalock-Taussig shunts. CONCLUSION: Magnetic resonance imaging provided detailed information about all aspects of cardiac morphology in patients with a suspected diagnosis of univentricular atrioventricular connection. Often it provided additional information to echocardiography. Its use in selected patients should give valuable complementary information.

Adolescent↗
PubMed1991

Left ventricular dysfunction in the fetus: relation to aortic valve anomalies and endocardial fibroelastosis.

OBJECTIVE: To examine the relation between a characteristic form of left ventricular dysfunction in the fetus and abnormalities of the aortic valve and endocardial fibroelastosis of the left ventricle. DESIGN: A retrospective study to examine the correlation between echocardiographic findings in the fetus and postnatal or necropsy findings. SETTING: Tertiary referral centre for fetal echocardiography. PATIENTS: Thirty fetuses showing a characteristic echocardiographic picture of left ventricular dysfunction. MAIN OUTCOME MEASURES: The relation between the prenatal echocardiographic features and the postnatal and necropsy findings. RESULTS: At presentation the size of the left ventricular cavity was normal or enlarged in all cases. The measurements of the orifice of the aortic root and mitral valve were either normal or small for the gestational age. The echocardiographic diagnosis made at presentation was critical aortic stenosis in all cases. At necropsy or postnatal examination the aortic valve was dysplastic and stenotic in 15 cases and the left ventricle had become hypoplastic in one of these. Aortic atresia was present in seven patients, three of whom had a hypoplastic left ventricle. In six patients the aortic valve was bicuspid although not obstructive. One of these patients had hypoplasia of the aortic arch and one had a hypoplastic left ventricle but in the remaining four patients endocardial fibroelastosis of the left ventricle was the only abnormality found. No follow up information was available in two. Of 26 patients for whom there was postmortem information, 24 had evidence of some degree of endocardial fibroelastosis of the left ventricle. Sequential observations showed that five cases developed into the hypoplastic left heart syndrome. CONCLUSIONS: This type of left ventricular dysfunction in the fetus is the result of an overlap of diseases, including primary left ventricular endocardial fibroelastosis, critical aortic stenosis, and the hypoplastic left heart syndrome.

Aortic Valve↗
PubMed1990

[Percutaneous closure of ductus arteriosus using the umbrella technic].

In four patients between three and five years of age we performed closure of open ductus arteriosus with the Rashkind umbrella technique after percutaneous approach from the right groin. The smallest internal ductus diameter measured between 2 and 4 mm, and pulmonary blood flow was from 1.4 to 2.0 times systemic flow. In all four patients, pulmonary artery pressure was normal. In three patients the ductus arteriosus was completely closed, in the fourth a small residual shunt persisted. There were no complications. We describe the method in detail.

Catheterization↗
PubMed1990

Balloon angioplasty for the treatment of native coarctation: results of Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Data on dilation of 141 native coarctation procedures in 140 patients between 3 days and 29 years of age were submitted to the Valvuloplasty and Angioplasty of Congenital Anomalies (VACA) Registry. Fifteen patients were less than 4 weeks old, 15 between 1 month and 12 months old and 110 patients over 1 year old. The immediate results confirmed that native coarctations could be effectively dilated in both infants and older children. The data do not support any conclusions concerning balloon size relative to results or complications. There were 24 complications (17%) reported with 1 death after 3 days and after intervening surgery in an infant with associated persistent ductus arteriosus. There were 2 early and 6 late "aneurysms" reported after the coarctation dilations with insufficient immediate and no long-term information about the significance of these. The VACA Registry data suggest that dilation of native coarctations can be performed effectively and relatively safely but do not answer whether this procedure should be performed.

Adult↗