Development and testing of the Helex septal occluder, a new expanded polytetrafluoroethylene atrial septal defect occlusion system.

BACKGROUND: A variety of transcatheter atrial septal defect (ASD) occluders are currently in use around the world. Although for the most part effective, all of these devices lack features that would be desirable in a "perfect" device. The Helex septal occluder is a new type of device designed to improve the results of transcatheter ASD closure. This study was designed to examine the effectiveness and safety of this occluder in an animal model. METHODS AND RESULTS: The Helex was implanted into 24 dogs with surgically created ASDs. Procedural details focusing on deployment, removal, and early closure rates were examined. Follow-up consisted of sequential transesophageal echocardiography and fluoroscopy as well as epicardial contrast echocardiography and angiography at the time of death. Specimens were examined grossly and histologically, and devices were tested for metal fatigue. All animals had successful ASD closure. Implantation was uncomplicated (mean fluoroscopy time 11.7 minutes), and removal or repositioning was always possible. Closure rate as judged by transesophageal echocardiography was 88% initially and 100% at 2-week follow-up. Devices rapidly became infiltrated with connective tissue without inflammation and were endothelialized over time. There were no instances of thromboembolism. A single wire-frame fracture occurred secondary to a prototype delivery system malfunction. CONCLUSIONS: The Helex septal occluder proved safe and effective for ASD closure. Several advantages over currently available devices were evident in this model. Controlled prospective clinical trials are needed.

Use of balloon-expandable stents for coarctation of the aorta: initial results and intermediate-term follow-up.

OBJECTIVES: In this study we report our preliminary results and intermediate-term follow-up (up to 3.5 years) of stent implantation for coarctation of the aorta (COA). BACKGROUND: Balloon angioplasty has gained acceptance as a modality of treatment for COA. Some patients do not respond optimally to balloon angioplasty alone. Balloon-expandable stents have been used in pulmonary arteries and large systemic arteries such as the femoroiliac vessels, with a significant improvement in vessel patency and a reduction in the pressure gradient compared with balloon angioplasty alone. METHODS: Nine patients (>10 years old) with COA in whom balloon dilation alone was thought to be ineffective underwent stent implantation. Seven patients had a previous operation or balloon dilation, or both, to relieve their coarctation but had a significant residual/recurrent gradient. RESULTS: At the time of stent implantation, the systolic and mean gradients decreased from a mean (+/-SEM) of 37 +/- 7 and 14 +/- 3 mm Hg to 4 +/- 1 and 2 +/- 0.6 mm Hg, respectively (p < or = 0.002). The coarctation diameter increased from a mean of 9 +/- 1 to 15 +/- 1 mm (p < 0.002). The patients have been followed for up to 42 months (mean 18, median 13) with no complications; the stents remain in position with no fracture. One patient underwent further successful dilation 3 years after stent implantation because of an exercise-induced gradient. No other intervention has been required. The systolic gradient at latest follow-up is 7 +/- 2 mm Hg. Only two (a 44-year old with diabetes and a 50-year old with long-standing hypertension) of five patients previously requiring antihypertensive treatment still remain on medications for blood pressure control. CONCLUSIONS: The use of stents in COA is a feasible alternative to surgical repair or balloon angioplasty in selected patients with an effective gradient reduction. Intermediate-term follow-up shows excellent gradient relief, with no complications in this group of patients.

Two-dimensional echocardiographic assessment of pulmonary artery and aortic arch anatomy in cyanotic infants.

To determine the feasibility and accuracy of noninvasive assessment of pulmonary artery and aortic arch anatomy, a prospective two-dimensional echocardiographic evaluation was performed in 20 consecutive cyanotic infants before cardiac catheterization and angiography. The echocardiographic assessment was correct with the following frequency: detection of left aortic arch in 13 of 13 infants, detection of right aortic arch in 7 of 7, identification of patent ductus arteriosus in 13 of 13 (one false positive finding), identification of a right pulmonary artery in 20 of 20, identification of a left pulmonary artery in 19 of 20, identification of the confluence of the right and left pulmonary arteries in 19 of 20 and identification of a main pulmonary artery in 14 of 16 (two false positive diagnoses by echocardiography). Echocardiographic estimates of arterial diameters were slightly smaller than those obtained by angiography. Mean vessel size (echocardiographic/angiographic diameter) was as follows: transverse aortic arch 8.6/10.6 mm, main pulmonary artery 5.7/6.3 mm, right pulmonary artery 4.1/4.2 mm and left pulmonary artery 4.2/3.9 mm. It is concluded that although two-dimensional echocardiography tends to underestimate vessel size, the qualitative assessment is adequate for planning a systemic to pulmonary artery anastomosis in selected infants with cyanotic forms of congenital heart disease.

Atrioventricular valve abnormalities in infancy: two-dimensional echocardiographic and angiocardiographic comparison.

The results of two-dimensional echocardiography and biplane angiocardiography from 47 infants with congenital atrioventricular (AV) valve abnormalities were compared. Eleven patients had atresia of the right AV valve, 10 had atresia of the left AV valve, 4 had hypoplasia of the right AV valve and 5 had hypoplasia of the left AV valve. Twelve patients had endocardial cushion defect, three had single ventricle and two had straddling of the left AV valve. There was agreement between the two techniques as to the number of AV valves present in each patient. The echocardiographic estimate of valve anular diameter was below normal in seven of the eight patients thought to have a hypoplastic anulus by angiocardiography. In 10 of the 12 patients with endocardial cushion defect, there was agreement between the two techniques as to the presence or absence of atrial and ventricular septal defect. The chordal attachments of straddling valves were better visualized by echocardiography; flow patterns and effective orifice size were better demonstrated by angiocardiography. The subcostal four chamber echocardiographic views and cranially angulated oblique angiocardiographic views were comparable and provided the best images for determination of the size and number of AV valves and their relation to the atrial and ventricular septa.

Acute results of balloon angioplasty of native coarctation versus recurrent aortic obstruction are equivalent. Valvuloplasty and Angioplasty of Congenital Anomalies (VACA) Registry Investigators.

OBJECTIVES: This study sought to compare the immediate results and risk factors for suboptimal outcomes of percutaneous balloon angioplasty for native versus recurrent aortic obstruction. BACKGROUND: Some cardiology centers have been reluctant to adopt balloon angioplasty for treatment of native aortic coarctation, while advocating balloon angioplasty over an operation for treatment of postsurgical or recurrent aortic obstruction. METHODS: Acute results were analyzed from 970 procedures (422 native and 548 recurrent lesions) performed between 1982 and 1995 in 907 patients from 25 centers. An acute suboptimal outcome was defined as one or more of the following: residual systolic pressure gradient > or = 20 mm Hg, residual proximal to distal systolic pressure ration > or = 1.33 or a major complication (death, aortic transmural tear, stroke). RESULTS: Bal loon angioplasty significantly (p = 0.0001) increased lesion diameter fo r both native (mean [+/= SD] 128 +/= 94%) and recurrent aortic obstruction (97 +/= 87%), with a significantly greater increase in the native group (p = 0.0001). A reduction in systolic pressure gradients was significant in both groups (p = 0.0001), but slightly higher (p = 0.01) for native (-74 +/- 24%) versus recurrent obstruction (-70 +/- 31%). Death associated with angioplasty was reported in 0.7% of patients with native and in 0.7% of patients with recurrent lesions (p = 1.00). An acute suboptimal outcome was noted with angioplasty in 19% of native and in 25% of recurrent lesions (p = 0.04). Significant independent risk factors included higher preangioplasty systolic gradient (odds ratio [OR] 1.39/10-mm Hg increment; 95% confidence interval [CI] 1.28 to 1.50, p = 0.0001), earlier study date (OR 0.92/1-year increment, 95% CI 1.02 to 1.26, p = 0.02) and recurrent obstruction (OR 1.39 vs. native lesions, 95% CI 1.00 to 1.94, p = 0.05). CONCLUSIONS: Acute results and complications of balloon angioplasty of native coarctation appear to be equivalent or slightly superior to those of recurrent aortic obstructions.

A gamma camera for medical applications, using a multiwire proportional counter.

A multiwire proportional counter gamma camera, specifically designed for nuclear medicine applications, is portable and weighs less than 50 lb including shielding and collimator. The basic operating characteristics have been investigated with various radioactive sealed sources. The camera demonstrates a peak count rate of 850,000 cps, an intrinsic spatial resolution of 2.5 mm, and excellent image uniformity when used with x-ray sources in the range of 22-81 keV. Tests of the device with Ta-178--a very promising, short half-life (9.3 min), low-energy radionuclide--using 20 mCi injections provided images of quality comparable to those obtained from 15 mCi Tc-99m studies with conventional imaging devices. The camera used with Ta-178 offers particular promise in first-pass nuclear cardiology studies. Considerably improved study quality will likely result in this area because of the increased injectable dose levels offered by Ta-178 combined with the high-count rate capability and improved resolution.

Long-term follow-up of patients with malformations for which definitive surgical repair has been available for 25 years or more.

The results of long-term follow-up studies of patients with five common congenital heart defects are reviewed. The lesions included are ventricular septal defect, atrial septal defect, patent ductus arteriosus, pulmonary stenosis and coarctation of the aorta. A definitive, rather than palliative, operation has been available for each of these lesions for more than 25 years. Therefore many patients who have undergone operation for one of these lesions are now reaching adulthood. Although most of these postoperative patients live a normal life, many have residuae or sequelae that require close observation or treatment. Other persistent abnormalities of the physical examination, electrocardiogram and chest radiogram are obvious but call for no precaution or treatment. We have drawn on our own experience and the published experience of others to identify those findings and historical factors that best reflect the long-term prognosis of these patients. In addition, recommendations concerning the need for continued prophylaxis against infective endocarditis, and the problems of insurability and employability of these postoperative patients are discussed.

Improvement in noninvasive electrophysiologic findings in children after transcatheter atrial septal defect closure.

To evaluate whether transcatheter closure of secundum atrial septal defects (ASD) affected noninvasive electrophysiologic variables in children, we reviewed the pre-procedural and 1-year postprocedural electrocardiograms and Holter recordings of 18 consecutive children referred for ASD closure. Patients included in the study were a mean of 5.0 years old (SD 1.1) and weighed a mean of 17.9 kg (SD 4.1). ASDs had a mean diameter of 14.0 mm (SD 2.4) and average shunt ratio (pulmonary-to-systemic flow) of 2.1:1. One year after occluder device placement, 9 children (50%) had detectable residual shunts by transthoracic echocardiograms, but only 2 (11%) had shunts that were felt to be possibly significant. One or more fractured occluder legs were noted by chest roentgenogram in 15 patients (83%). Electrocardiograms at follow-up demonstrated improvement in right ventricular dilation in 4 of 7 patients, right atrial enlargement in 3 of 4 patients, and 1 degree atrioventricular block in 2 of 3 patients. Holter recordings showed a decreased incidence of accelerated atrial rhythm in 3 of 7 patients, prolonged junctional escape rhythm in 2 of 2 patients, and premature atrial contractions in 2 of 2 patients. No finding correlated with patient age, defect or occluder diameter, occluder leg fracture(s), or residual defects. These improvements in electrophysiologic abnormalities compare favorably with changes seen 1 year after surgical closure. In conclusion, placement of a transcatheter ASD device in children diminishes noninvasive electrophysiologic abnormalities at 1-year follow-up. By relieving hemodynamic stress caused by an ASD in childhood, a transcatheter device may prevent arrhythmia disturbance later in life.

Resolution and accuracy in two dimensional echocardiography.

The resolution and accuracy of commercially available two dimensional echocardiographic systems were tested by imaging two types of in vitro test objects. One consisted of a series of fine parallel threads spaced at known intervals and the other was a tissue phantom in which a series of holes of known size had been cut. The echocardiographic systems tested included a mechanical single element sector scanner, a three element rotary sector scanner and a phased array system. Azimuthal resolution, lateral resolution and accuracy of horizontal distance measurements were assessed at depths of 2 and 6 cm. For each system, azimuthal resolution was better than lateral resolution, especially when assessed with use of the parallel threads. When the tissue phantom was imaged, the best resolution (2 mm in azimuthal and lateral directions) was obtained with the highest frequency transducer tested (3.5 MHz). The apparent size of a tissue defect was sensitive to gain settings, especially at a depth of 2 cm with lower frequency transducers; at a depth of 6 cm, echographic measurements of defect size were accurate to within 2.5 mm. Recent applications of two dimensional echocardiography require near the apparent limits of current equipment. It is recommended that the highest frequency transducer and lowest possible gain settings be used in these situations.

Echocardiographic pulsed Doppler features of absent pulmonary valve syndrome in the neonate.

M mode echocardiography was used to evaluate nine neonates with absent pulmonary valve syndrome. Six were also studied with two dimensional echocardiography and two with pulsed Doppler echocardiography. M mode echocardiography demonstrated a large, overriding great artery and right ventricular dilation in all nine patients and abnormal septal motion in eight. Two dimensional echocardiography demonstrated aneurysmal dilation of the main pulmonary artery in all six patients studied. Pulsed Doppler echocardiography in the two infants studied demonstrated anterograde systolic and retrograde diastolic flow in the main pulmonary artery and right ventricular outflow tract. The echocardiographic features of absent pulmonary valve syndrome appear to be unique and allow the diagnosis to be made noninvasively, thus obviating or delaying the need for potentially high risk cardiac catheterization.

Ventricular septal defect in infancy: detection with two dimensional echocardiography.

To determine the sensitivity and specificity of two dimensional echocardiography in detecting ventricular septal defect two dimensional echocardiograms were performed on 53 infants under 1 year of age. The diagnosis of ventricular septal defect was confirmed by cardiac catheterization in 27 patients; an intact ventricular septum was confirmed by catheterization in 18 and clinically in 8. Using a 35 degree mechanical sector scanner with a 3.5 megahertz transducer, we imaged the ventricular septum in the long axis and in a four chamber view (apical or subcostal, or both). Images were recorded on videotape and reviewed independently by two observers unaware of the diagnosis. Interobserver agreement was 94 percent. Among the 27 patients with a ventricular septal defect, the lesion was correctly identified in 20 (74 percent) and was undetected in 7 (3 of whom had a defect less than 4 mm in diameter, as determined by angiography). No defect less than 4 mm in diameter was detected. Among the 26 patients with an intact septum, a defect was correctly excluded in 23 (88 percent); a false positive diagnosis was made in 3. The apical and subcostal views demonstrated the greatest number of defects (20 of 20), but also gave the highest number of false positive diagnoses (3 of 3). The long axis view was helpful when positive, but showed only 9 of 20 of the defects. In this study, two dimensional echocardiography detected approximately three fourths of ventricular septal defects large enough to warrant cardiac catheterization in the 1st year of life. False positive diagnoses were related to dropout of echoes in the membranous septum when imaged in the four chamber views.

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.

Intermediate-term outcome of transcatheter secundum atrial septal defect closure using the Bard Clamshell Septal Umbrella.

Of 31 patients who underwent transcatheter atrial septal defect occlusion with the Bard Clamshell Septal Umbrella, only 1 had a clinically significant residual atrial septal defect at a mean follow-up of 41 months. All patients were asymptomatic despite the occurrence of device arm fractures in 84% of these patients.

Atrioventricular valve anular diameter: two-dimensional echocardiographic-autopsy correlation.

To study the accuracy of 2-dimensional echocardiography (2-D echo) in estimating mitral and tricuspid anular diameter, 2-D echo estimates were compared with autopsy measurements of anular diameter in 21 children studied by echo within 30 days of death. The mitral anulus was measured from the left parasternal long axis view and the apical or subcostal 4-chamber image and the tricuspid anulus from the 4-chamber view. Comparable measurements were made from the autopsy specimen with calipers. The correlation coefficient for echocardiographic vs autopsy measurements was 0.79 (standard error of the estimate 2.8 mm) (mitral long axis r = 0.76, mitral 4-chamber r = 0.85, tricuspid 4-chamber r = 0.76). Echo measurements exceeded the corresponding autopsy measurements by an average of 17%; this was at least partially attributed to shrinkage of the specimen during fixation. Thus, 2-D echo may be used to provide a reasonable estimate of mitral and tricuspid anular diameter.

Accuracy of two-dimensional echocardiography in the diagnosis of congenital heart disease.

To assess the accuracy of 2-dimensional (2-D) echocardiography in the evaluation of cardiac anatomy in patients with congenital heart disease, 2-D echocardiograms were performed in 126 infants and children before cardiac catheterization and angiocardiography. The segmental echocardiographic analysis included determination of intracardiac, great artery, systemic venous and pulmonary venous anatomy. The 126 patients had 259 separate cardiovascular abnormalities, of which 226 (87%) were prospectively identified by 2-D echocardiography. There were 8 false-positive diagnoses. The most common lesions and the sensitivity and specificity of echocardiography were: patent ductus arteriosus, 41 patients (83% and 100%, respectively), ventricular septal defect, 35 patients (86% and 100%); atrial septal defect, 26 patients (85% and 99%); pulmonary valve stenosis, 25 patients (77% and 97%), transposition of the great arteries, 16 patients (100% and 100%); and total anomalous pulmonary venous connection, 14 patients (85% and 100%). Less common defects and their rate of detection included coarctation of the aorta, 10 of 12 patients; atrioventricular canal, 10 of 10 patients; tetralogy of Fallot, 10 of 10 patients; aortic valve stenosis 8 of 8 patients; right aortic arch, 8 of 8 patients; interrupted aortic arch, 4 of 4 patients; and unilateral pulmonary vein atresia, 0 of 1 patient. In 33 patients (26%), the errors in echocardiographic analysis were judged to have surgical importance. Most errors were the result of overlooking or misinterpreting data that had been appropriately recorded on videotape. Pulmonary valve stenosis and patent ductus arteriosus are the lesions most likely to be misdiagnosed by ultrasound studies relying on imaging alone.

Transcatheter coil embolization of abnormal vascular connections using a new type of delivery catheter for enhanced control.

A new type of delivery catheter, designed with a 0.033-inch distal tip that grips a 0.038-inch Gianturco coil, was used to occlude 61 abnormal vascular connections in 44 patients with a complete closure rate of 87%. Withdrawal (n = 6) or repositioning (n = 2) of an inappropriately positioned coil was necessary in 8 of 44 patients, and was successfully achieved in all by the delivery catheter without need for additional equipment.

Surgical repair of severe bilateral branch pulmonary artery stenosis.

Management options for severe, bilateral branch pulmonary artery stenosis include percutaneous balloon dilation and direct surgical correction. Results with both balloon angioplasty and operation have been somewhat unpredictable. We report a case of staged surgical correction involving bilateral branch pulmonary artery reconstruction.

Anomalous origin of left coronary from right pulmonary artery in hypoplastic left heart syndrome.

An infant with hypoplastic left heart syndrome presented for surgical repair at 9 months of age, the ductus having remained open in the presence of a restrictive atrial septal defect. In addition, an anomalous left coronary artery originating from the right pulmonary artery was found. After preliminary blade/balloon atrial septostomy, a successful modified Norwood procedure with concomitant reimplantation of the anomalous coronary artery was performed.

Results of the double switch operation in the current era.

BACKGROUND: In patients with atrioventricular and arterioventricular discordance congenitally corrected transposition, the morphologically right ventricle may progressively deteriorate while functioning in the systemic circuit. The double switch operation has been proposed to limit this functional deterioration. METHODS: From October 1993 to August 1998, the records of 27 patients with congenitally corrected transposition were reviewed. Age at operation ranged from 3 months to 55 years. Associated defects included ventricular septal defects in 18, pulmonary atresia in 7, and pulmonary stenosis in 11 patients. Twenty-two patients had double switch operations (10 arterial switch plus Senning procedures and 12 Rastelli plus Senning procedures). Five patients were not candidates for the double switch. Before the double switch, 6 patients required pulmonary artery banding and 10 had functioning systemic to pulmonary artery or cavopulmonary shunts. RESULTS: There was no early or late mortality. Two patients required pacemaker implantation, both later regained normal sinus rhythm. Tricuspid valve function improved in all patients except one. Moderate left ventricular dysfunction developed 5 months postoperatively in 1 patient. CONCLUSIONS: The double switch operation can be performed in selected patients with minimal early morbidity and mortality. Longer follow-up is necessary to determine whether this complex approach is indeed warranted.

Immediate post-operative balloon dilatation of neonatal long segment stenosis of the descending thoracic aorta.

During surgical repair of a neonatal coarctation it was recognized that this was a rare, previously undescribed form of stenosis of the entire descending thoracic aorta. A few hours after the end-to-end surgical repair, the child underwent successful balloon angioplasty, involving the entire descending thoracic aorta, and in which we intentionally avoided the surgical site.