Percutaneous transluminal balloon dilatation for discrete subaortic stenosis

Effects of chronic low-dose radiation on cataract prevalence and characterization in wild boar (Sus scrofa) from Fukushima, Japan

This study evaluated cataracts in wild boar exposed to chronic low-dose radiation. We examined wild boar from within and outside the Fukushima Exclusion Zone for nuclear, cortical, and posterior subcapsular (PSC) cataracts in vivo and photographically. Plausible upper-bound, lifetime radiation dose for each boar was estimated from radioactivity levels in each animal's home range combined with tissue concentrations of 134+137Cesium. Fifteen exposed and twenty control boar were evaluated. There were no significant differences in overall prevalence or score for cortical or PSC cataracts between exposed and control animals. Nuclear (centrally located) cataracts were significantly more prevalent in exposed boar (p < 0.05) and had statistically higher median scores. Plausible upper-bound, lifetime radiation dose ranged from 1 to 1,600 mGy in exposed animals, with no correlation between dose and cortical or PSC score. While radiation dose and nuclear score were positively associated, the impact of age could not be completely separated from the relationship. Additionally, the clinical significance of even the highest scoring nuclear cataract was negligible. Based on the population sampled, wild boar in the Fukushima Exclusion Zone do not have a significantly higher prevalence or risk of cortical or PSC cataracts compared to control animals.

Long-Term Outcome of Patients With Isolated Thin Discrete Subaortic Stenosis Treated by Balloon Dilation

Background—

Transluminal balloon tearing of the membrane in a thin discrete subaortic stenosis is an alternative to membrane surgical resection. However, the long-term outcome of patients with isolated thin discrete subaortic stenosis treated by transluminal balloon tearing remains unknown.

Methods and Results—

This 25-year study describes findings from 76 patients with isolated thin discrete subaortic stenosis who underwent percutaneous transluminal balloon tearing of the membrane and were followed up for a mean period of 16±6 years. The age at presentation had a wide range (2–67 years). The mean age at treatment was 19±16 years. Immediately after treatment, the subvalvular gradient decreased from 70±27 to 18±12 mm Hg ( P <0.001). No significant postprocedural aortic regurgitation was observed. After a mean follow-up time of 16±6 years, 11 patients (15%) developed restenosis, 3 patients (4%) progressed to muscular obstructive disease, and 1 patient (1.3%) developed a new distant obstructive membrane. Twelve patients (16%) were redilated at a mean of 5±3 years after their first treatment, and 4 patients (5%) underwent surgery at a mean of 3±2 years after their first treatment. Fifty-eight patients (77%) remained alive and free of redilation or surgery at follow-up. Larger annulus diameter and thinner membranes were independent factors associated with better long-term results.

Conclusions—

Most patients (77%) with isolated thin discrete subaortic stenosis treated with transluminal balloon tearing of the membrane had sustained relief at subsequent follow-ups without restenosis, the need for surgery, progression to muscular obstructive disease, or an increase in the degree of aortic regurgitation.

[Guidelines of clinical practice of the Spanish Society of Cardiology. Requirements and equipment of invasive techniques in pediatric cardiology: clinical application]

Invasive techniques in pediatric cardiology have experienced a big change since the 80's. The growth of non-invasive methods for diagnosing congenital heart defects has made the number of diagnostic catheterizations decrease remarkably. On the other hand, the notable development of pediatric interventional catheterization techniques will allow that, in the near future, the number of therapeutic catheterizations overcomes the diagnostic ones in our country. The former are more difficult and dangerous, so they require experienced and skilled hands and more economic resources. This chapter is divided in three main sections: I) Requirements and equipment needed for pediatric invasive techniques; II) Current indications, contraindications and complications of the diagnostic catheterization, and III) Techniques, indications and results of pediatric therapeutic catheterization: current state. Likewise, we state the suitability or not for these therapeutic procedures in different cardiac anomalies.

Initial experience with balloon dilatation of supravalvar aortic stenosis

Primary balloon dilatation of supravalvar aortic stenosis was attempted in three patients: a 20 year old woman, a seven month old boy, and a 12 year old girl. Balloon catheters (Mansfield) with diameters of 25 mm, 8 mm, and 15 mm were used in the three patients respectively. The systolic pressure gradient across the aortic narrowing decreased considerably and the diameter of the constricted area increased significantly. Balloon dilatation was feasible and provided good immediate results and sustained relief of supravalvar aortic stenosis in these three patients. However, a larger study is needed to establish the place of this procedure in treatment.

Balloon dilation of congenital subaortic stenosis in the dog

Balloon dilation during cardiac catheterization was evaluated for the treatment of congenital subaortic stenosis (SAS) in nine dogs. Under general anesthesia, bilateral cardiac catheterization was performed through the right jugular vein and carotid artery. Thermodilution cardiac output, and left ventricular and aortic root pressures and angiograms were obtained before and after balloon dilation. Balloons measuring 18-20 mm in diameter and 30-40 mm in length were positioned across the stenosis and three inflations 4-5 minutes apart were performed. There was no significant change in cardiac output, aortic pressure, or degree of aortic regurgitation after balloon dilation. For the entire group balloon dilation resulted in significant decreases in left ventricular systolic pressure (-61.2 +/- 37.2 mm Hg [mean change +/- SD], range -14 to -123), mean systolic pressure gradient (-39.6 +/- 24.4 mm Hg, range -8.4 to -72.2), and peak systolic pressure gradient (-64.3 +/- 46.5 mm Hg, range -17 to -143). Calculated left ventricular outflow cross-sectional area increased significantly (+.4 +/- .5 cm2, range -.06 to + 1.30). Clinical signs improved in the five symptomatic dogs. Individual hemodynamic responses varied widely, but the magnitude of improvement correlated with the severity of obstruction. Three dogs showed a decrease of 60% or greater (> or = 100 mm Hg), and six dogs showed a decrease of 25-50% (17-71 mm Hg) in peak systolic gradient after balloon dilation. Complications were frequent but most were transient and manageable. These preliminary results suggest that balloon dilation can acutely decrease outflow resistance in dogs with SAS and may be effective therapy for some affected dogs.

"Acquired" subvalvular aortic stenosis after repair of a ventricular septal defect

Of 353 children who underwent surgical repair of a congenital heart defect, including closure of a ventricular septal defect (VSD), 12 patients (four with tetralogy of Fallot, five with a VSD, and three with a double-outlet right ventricle) developed subaortic stenosis, which was diagnosed one to six years after the surgical procedure. Five patients required surgical treatment of the subaortic stenosis, and one required percutaneous balloon angioplasty. Postsurgical subaortic stenosis appears to be an uncommon progressive acquired disease.

Echocardiographic determinants of outcome after percutaneous transluminal balloon dilatation of discrete subaortic stenosis

Eleven patients (seven females and four males; age 4 to 24 years) with discrete subaortic stenosis (DSS) diagnosed on echocardiography were subjected to balloon dilatation. The site of the obstruction was 1 to 8 mm below the aortic valve. On the basis of echocardiographic appearance, the patients could be divided into three groups. Group I patients had a uniformly thin (1 to 3 mm) obstructing "membrane" (n = 7). Group II patients had a thin obstructing "membrane" present at the tip of a thick bulge from the interventricular septum (n = 2) (intermediate form). Group III patients had an obstruction caused by a thick ridge of tissue (6 to 8 mm thick, n = 2). Maximum inflatable diameter of the balloon used was less than or equal to the aortic valve anulus. After balloon dilatation in group I, the gradients across the obstruction fell from 86.6 +/- 16.9 mm Hg to 24.0 +/- 13.1 mm Hg. Relief of obstruction persisted on follow-up of 3 to 24 months (gradient 28.8 +/- 15.7 mm Hg). In group II patients gradients fell from 116 and 40 mm Hg to 58 and 20 mm Hg, respectively immediately after balloon dilatation. On follow-up of 6 and 9 months the gradients have increased to 76 and 32 mm Hg, respectively. In group III the gradients fell from 64 and 70 mm Hg to 15 and 16 mm Hg, respectively, immediately after balloon dilatation, which increased to 58 and 60 mm Hg, respectively, within 24 hours and persisted around that level at 3 months' follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate and follow-up results of transluminal balloon dilation for discrete subaortic stenosis

This study presents the findings in 33 patients with discrete subaortic stenosis who were treated by percutaneous balloon dilation and were followed up for 2 months to 6.2 years (mean 34 +/- 21 months). The mean age was 13 +/- 11 years; 10 (30%) were female and 23 (70%) male. Associated malformations were observed in nine patients (27%). All patients underwent noninvasive studies and cardiac catheterization. The mean value to membrane distance was 4.5 +/- 2 mm/m2. After balloon dilation, the pressure gradient from the left ventricle to the aorta decreased from 68 +/- 30 to 20 +/- 13 mm Hg (p less than 0.00001); there were no significant changes in the degree of aortic regurgitation. A fluttering and widely mobile remaining membrane was clearly visualized after dilation. Better immediate results were obtained in patients with a smaller baseline gradient, a larger aortic anulus and a longer valve to membrane distance. Serial follow-up echographic studies were available in 30 patients, and 18 hemodynamic reevaluations were performed in 13 patients. However, seven patients who demonstrated restenosis underwent redilation at a mean of 29 +/- 17 months after the first dilation. Redilation in six of the seven patients obtained benefits similar to those observed at the first dilation. Only one patient with unsuccessful redilation required surgery. The mean value of the last explored residual gradient (on hemodynamic or Doppler study) in the remaining 32 patients was 21 +/- 10 mm Hg. No significant changes were observed in the angiographic evolution of aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon dilation of postsurgical subaortic obstruction

Two children aged 10 and 5.5 years underwent balloon dilation for postsurgical subaortic obstruction. The outcome and the role of this procedure are discussed.

Transluminal balloon dilatation for discrete subaortic stenosis in adults and children: early and intermediate results

Seven patients (four adults, three children) with discrete subaortic membranous stenosis underwent balloon dilatation using a single or double balloon technique with reduction in systolic gradient across the membrane from 100.42 +/- 19.23 to 29.14 +/- 12.54 mmHg (P less than 0.001). Echocardiography demonstrated thin membranes in all the patients and postprocedure torn fragments could be visualized. The excellent hemodynamic benefits are sustained during 4-24 months follow-up. The results indicate that transluminal balloon dilatation can be a safe and effective treatment for thin subaortic membrane.

Balloon aortic valvuloplasty in children

The technique of balloon aortic valvuloplasty has been used in infants, children, and adults since its first description in 1983. Immediate results reported by several workers and intermediate-term results by a few workers appear encouraging. Complications are minimal although potential for arterial complications and aortic insufficiency should be recognized. Significant restenosis rates at intermediate-term follow-up have been reported and could be minimized by reducing the risk factors associated with recurrence. Echo-Doppler studies are useful in follow-up evaluation of balloon valvuloplasty. The results seem to compare favorably with those following surgical valvotomy. The indications are essentially the same as those used for surgery; a gradient in excess of 80 mmHg irrespective of symptoms or a gradient greater than or equal to 50 mmHg with symptoms or ST-T wave changes. Previous surgical valvotomy is not a contraindication for balloon valvuloplasty. The technique is applicable to subaortic membranous stenosis as well. Thus far only one- to two-year follow-up results are available. Five- to ten-year follow-up results to document long-term effectiveness of balloon aortic valvuloplasty are needed. Miniaturization of currently bulky dilating catheter systems and improving rapidity of inflation/deflation of balloons are necessary to increase safety and effectiveness of these techniques in infants and children. Meticulous attention to the details of the technique and further refinement of the procedure may further increase effectiveness and reduce the complication rate.

Balloon dilation of miscellaneous lesions: results of Valvuloplasty and Angioplasty of Congenital Anomalies Registry

Data on 111 lesions, in addition to pulmonary valve, aortic valve, branch pulmonary stenosis, native coarctation and recoarctation, were submitted to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry. Because there was a very heterogenous group of lesions both in types of lesions and techniques of dilation, only minimal data can be offered concerning the efficacy of the dilation of any or all of these lesions. The registry data do, however, demonstrate the safety of these dilations compared to alternative surgical therapy.

Balloon dilation catheters

Catheter therapy has gained an important role in the treatment of congenital heart disease. The cumulative experience with vascular and valvular balloon dilations has demonstrated low mortality and morbidity with short-term results similar to surgery. Currently, balloon dilation is an accepted treatment for valvular pulmonary stenosis, distal pulmonary artery stenosis, recurrent coarctation, rheumatic mitral stenosis, congenital valvular aortic stenosis, and intra-atrial baffle obstruction. Except for patients at high surgical risk, balloon dilation of native coarctation is considered investigational at most institutions but accepted at others. No conclusive evaluation is yet possible for dilation of bioprosthetic valves and membranous subaortic stenosis. Individual pulmonary veins appear undilatable. Various devices are available for closure of extra- and intracardiac communications. Transcatheter closure of aortopulmonary collaterals and arteriovenous malformations is now well established at some centers. In selected patients, therapeutic embolization of surgical shunts can replace surgery. Transcatheter closure of the patent ductus arteriosus has become routine at some centers. Nonsurgical closure of atrial and ventricular septal defects has entered clinical trials, and preliminary results appear very promising. Blade atrioseptostomy and foreign body retrieval are well established. Improvement of existing procedures and implementation of new concepts will consolidate the role of catheter therapy in congenital and acquired heart disease.

Abrupt homeostatic responses to transient intracardiac occlusion during balloon valvuloplasty

The present study analyzes the hemodynamics of intracardiac occlusive periods during balloon mitral or aortic valvuloplasty and compares them with immediate plasma levels of atrial natriuretic factor (ANF), vasopressin and renin activity. Forty-nine patients were studied; 33 of them had mitral stenosis and 16 had aortic stenosis. The mean age was 52 +/- 17 years. During dilations pressures were monitored from the ascending aorta and left atrium. Plasma levels of ANF, vasopressin and renin were serially determined at baseline, after diagnostic procedures, within 15 to 30 seconds after the first 2 occlusive dilations, and 1 and 7 hours later. There were no significant changes in plasma renin throughout the study stages. ANF and vasopressin significantly increased after the dilations. These hormonal changes were related to the significant hemodynamic changes observed during intracardiac occlusion. The left atrial pressure correlated directly and significantly (r = 0.54, p less than 0.001) with plasma ANF levels throughout the conditions. On the other hand, the plasma vasopressin also correlated (r = 0.76, p less than 0.001) with systemic pressure in an exponential fashion. These findings show that abrupt releases of ANF and vasopressin occur immediately after intracardiac occlusive periods as a response to the acute and transient hemodynamic changes observed.

Interventional catheterization in pediatric congenital and acquired heart disease

The present status of catheter-directed therapy in pediatric congenital and acquired heart disease is reviewed. Balloon pulmonary valvotomy, established as the procedure of choice for children and adults with isolated pulmonary stenosis, has now been extended to neonates with critical pulmonary stenosis. Balloon mitral and aortic valvotomy are being performed for congenital and acquired stenoses, although indications and optimal techniques remain to be established. Balloon angioplasty of coarctation effectively relieves obstruction in native and post-operative aortic arch stenoses, but remains controversial due to late aneurysm formation. Balloon angioplasty of branch pulmonary artery hypoplasia and stenosis, despite a relatively low success rate and significant complications, remains the procedure of choice due to lack of better therapeutic options. Transcatheter closure of congenital and acquired vessels and defects is being performed with increasing frequency. Embolization of aortopulmonary collaterals and shunts using Gianturco coils is safe and effective in selected patients. Although Rash-kind umbrellas are most commonly used for closure of a patent ductus arteriosus, their use, especially in closing intracardiac defects, remains investigational.

Physiopathology of transient ventricular occlusion during balloon valvuloplasty for pulmonic or aortic stenosis

Hemodynamic observations were made at different cardiac levels during transient balloon occlusion at the time of aortic or pulmonary valvuloplasty in 37 patients (mean age 8 +/- 9 years); 22 had pulmonary stenosis and 15 had aortic stenosis (6 valvular and 9 discrete subvalvular types). Eighty-two tentative dilatations were performed in patients with pulmonary stenosis and 61 in patients with aortic stenosis. The hemodynamics of the right and left heart were monitored during inflation-deflation time. From selected tracings mean beat-to-beat pressures curves were constructed during occlusion-recovery time. The cycle length (RR interval) did not change significantly during occlusion, except for patients with pulmonary occlusion and patent foramen ovale, where a significant increase in cycle length (p less than 0.01) was observed during recovery time. The mean maximal increase in ventricular pressure reached 95% of basal values for the right ventricle and 58% for the left ventricle. The hypertension was retrogradely transmitted to all cardiac chambers. Angiographic observations during occlusion suggest that the atrioventricular valves and the foramen ovale, when patent, become escape orifices during occlusion, for adapting and relieving intracavitary pressures. The ventricle seems to adapt to sudden occlusion by generating hypertensive and hypokinetic contractions, with atrioventricular regurgitation.

Balloon pulmonary valvotomy: palliation for cyanotic heart disease

Balloon pulmonary valvotomy was attempted in eight children with cyanotic congenital heart disease and pulmonic stenosis who were scheduled for a palliative procedure (shunt). In seven patients the balloon could be positioned across the pulmonary anulus, and valvotomy was performed. Five of the patients had tetralogy of Fallot with multiple levels of pulmonary outflow obstruction. For all patients in whom the balloon could be properly positioned the valvotomy was successful, as judged by arterial hemoglobin saturation, which increased from 72% +/- 5% to 83% +/- 5% (p less than .005). Valvotomy was followed by an immediate rise in mean pulmonary artery pressure (12.6 +/- 2.8 to 18.3 +/- 4.8 mm Hg, p less than 0.05) and a decline in hematocrit level at 2 months (54% +/- 5% to 47% +/- 4%, p less than 0.05). There was no mortality or complication from the valvotomy, and the need for a systemic to pulmonary artery shunt was eliminated in six of eight patients. Follow-up has ranged from 0.5 to 2.8 years. This trial indicates that balloon pulmonary valvotomy can be safely performed and is effective palliation in selected patients with cyanotic heart disease that is not suitable for primary repair. The increased pulmonary flow may improve oxygenation and growth of the pulmonary arteries without the need of a systemic to pulmonary artery shunt.