Lee N. Benson

Angiographic classification of the isolated, persistently patent ductus arteriosus and implications for percutaneous catheter occlusion

Abstract A percutaneous catheter technique for permanent closure of the isolated, persistently patent ductus arteriosus (PDA) was first described in 1967. 1 The development of a spring-loaded double foam disc occluder on a miniaturized (8 or 11Fr) delivery system 2 placed transvenously 3,4 has allowed this management approach to become an effective alternative to surgery in infants and children. The recent description of an improved release technique and the application of topical thrombin onto the foam of the occluder may further reduce embolization risk and increase total occlusion rates. 5 Little attention, however, has been given to the variation in anatomy and topology of the isolated PDA and its influence, if any, on the technique of catheter occlusion. This report describes the angiographic appearances of isolated PDA as seen at the time of catheter occlusion, presents a classification of the observed variations and comments on how these may affect the procedure.

Complications associated with pediatric cardiac catheterization

OBJECTIVES The aim of this study was to determine the relative risks of pediatric diagnostic, interventional and electrophysiologic catheterizations. BACKGROUND The role of the pediatric catheterization laboratory has evolved in the last decade as a therapeutic modality, although remaining an important tool for anatomic and hemodynamic diagnosis. METHODS A study of 4,952 consecutive pediatric catheterization procedures was undertaken. RESULTS Patient ages ranged from 1 day to 20 years (median 2.9 years). One or more complications occurred in 436 studies (8.8%) and were classified as major in 102 and minor in 458, with vascular complications (n=189; 3.8% of procedures) the most common adverse event. Arrhythmic complications (n=24) were the most common major complication. Death occurred in seven cases (0.14%) as a direct complication of the procedure and was more common in infants (n=5). Independent risk factors for complications included a young patient age and undergoing an interventional procedure. CONCLUSIONS Complications continue to be associated with pediatric cardiac catheterization. Efforts should be directed to improving equipment for flexibility and size, and finding alternative methods for vascular access. Patient age and interventional studies are risk factors for morbidity and mortality.

Balloon aortic valvuloplasty: Results of the Valvuloplasty and Angioplasty of Congenital Anomalies Registry

Data from 204 children and infants who underwent aortic balloon valvuloplasty between 1982 and 1986, reported to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry, were reviewed. Valvuloplasty was successful in 192 of 204 children, reducing the peak systolic left ventricular ejection gradient from 77 +/- 2 to 30 +/- 1 mm Hg, p less than 0.001. The same degree of aortic stenosis gradients reduction was noted in both the 38 children under 1 year of age and in the 166 children over 1 year of age. Significant complications included death, aortic regurgitation and femoral artery thrombosis or damage. The incidence of these complications correlated with the age of the child, the ratio of valvuloplasty balloon size/anulus size, or both. The data suggest that percutaneous balloon valvuloplasty provides effective acute relief of valvar aortic stenosis in both infants and children. However, long-term follow-up data are necessary before balloon valvuloplasty can be established as a treatment of choice for congenital valvar aortic stenosis.

Evolving strategies and improving outcomes of the modified Norwood procedure: a 10-year single-institution experience

BACKGROUND This study reviews our 10-year experience with the modified Norwood procedure to determine its early and midterm outcomes. The focus is on the impact of evolving management strategies and accumulated institutional experience. METHODS A modified Norwood operation was performed in 171 infants over a 10-year period. Sixty-eight percent of the infants were male, the median age at operation was 6 days (range 1 to 175 days), and the median weight was 3.3 kg (range 1.7 to 4.8 kg). The 10-year period was divided into three eras: era I; 1990 through 1993; era II; 1994 through 1997; and era III; 1998 into 2000. Outcomes and risk factors for mortality were sought. RESULTS Hypoplastic left heart syndrome or a variant was the primary diagnosis in 118 infants (69%). The overall 5-year survival rate was 43%. Multivariate analysis revealed that only need of preoperative ventilatory support, earlier date of operation, and lower weight at operation were significant independent predictors of increased time-related mortality. Morphologic features such as a diagnosis other than hypoplastic left heart syndrome, ascending aortic size, and noncardiac anomalies were not significantly associated with an increased risk of death. The hospital survival rate for stage-one palliation in era III was 82%, significantly better than that in the preceding eras (p < 0.001). Attrition between stages one and two accounted for a 15% mortality rate among hospital survivors. CONCLUSIONS With increasing experience and improvements in perioperative care and surgical technique, good outcomes can be expected for the first-stage modified Norwood procedure. Greater monitoring of patients in the interstage period may reduce interval mortality and improve overall survival.

Transcatheter occlusion of the persistently patent ductus arteriosus. Forty-month follow-up and prevalence of residual shunting.

BackgroundPercutaneous closure of the persistently patent ductus arteriosus with the Rashkind prosthesis is an established effective therapeutic modality, although some patients are left with residual shunting. To evaluate this, a retrospective study of the prevalence of persistent shunting over a 40-month period in the first 190 patients was undertaken. Methods and ResultsAll patients (male 45, female 145; mean age, 3.9 % 3.6 years; range, 5 months to 20 years) had serial clinical and color-flow echocardiographic follow-up at 6–12-month intervals (range, 6–40 months). Four patients required surgical removal of an embolized device, leaving a cohort of 186 patients in whom 196 procedures were performed, resulting in successful placement of 195 devices (43 17-mm [22%] and 152 12-mm [78% o]). Complications occurred in seven of 195 procedures (3.6%). Nine of 10 attempted reocclusions (all with 12-mm devices) were successful. The prevalence of residual shunting was 38% o at 1 year, 18% at 2 years, and 8% at 40 months. Patients with ductus measuring less than 4 mm had a higher success of initial occlusion. Thirty-four patients were left with residual shunting determined by color-flow Doppler study, but no anatomic or echocardiographic features were found predictive for residual shunting. All remain asymptomatic with 26 (76%) having no detectable murmur, two (6%) a continuous murmur, and six (18%) a systolic murmur. ConclusionsCatheter occlusion will obviate the need for surgery in the majority of patients presenting with persistently patent ductus arteriosus. Reocclusion has been found feasible in those with continuous murmurs (nine of nine) and should be offiered early because it is unlikely for spontaneous closure to occur in this group. It appears prudent to follow those with small residual shunting because further spontaneous closure can occur.

Heparin Therapy in Pediatric Patients: A Prospective Cohort Study

ABSTRACT: Current guidelines for heparin therapy in pediatric patients have been extrapolated from trials in adult patients without rigorous evaluation of efficacy and safety. We prospectively monitored consecutive pediatric patients receiving systemic doses of heparin over 10 mo at one institution using a predetermined nomogram to monitor maintenance therapy. Sixty-five consecutive children; 38 males and 27 females, received systemic doses of heparin. Thirty children had deep venous thrombosis and/or pulmonary embolism; 11 had arterial thrombi, most frequently after diagnostic angiography; and the remaining 24 received heparin prophylactically, for congenital heart disease. Twenty-nine (45%) of the 65 patients were less than 1 y of age and 22 (34%) were 10 y or older. Congenital heart disease was the predominant diagnosis under 1 y and deep venous thrombosis in older children. After a bolus dose of 50 U/kg, 39% of children (n = 30) achieved a minimal level activated partial thromboplastin time (APTT). Sixty-eight percent of children achieved a minimal level APTT by 24 h and 81% by 48 h. For all 65 children, APTT values were within the therapeutic range 43% of the time. APTT values outside the therapeutic range were twice as likely to be low as high. The average amount of heparin required to maintain therapeutic APTT values for children was 22 U/kg/h: 28 U/kg/h for infants <1 y and 20 U/kg/h for the rest. Bleeding was rare (2%) and mild. Documented recurrent thrombotic disease was more common (7%) with associated morbidity. In summary, a commonly used protocol for administration of heparin to children was rigorously evaluated and shown to provide insufficient amounts of heparin in the first days of treatment. Average requirements of heparin per kilogram per hour were determined and will form the bases of future studies.

Endovascular Stents in the Pulmonary Circulation Clinical Impact on Management and Medium-term Follow-up

BACKGROUND The use of endovascular stents to relieve obstructions in the setting of non-balloon dilatable pulmonary artery stenosis has been encouraging. The benefits in management and the potential for restenosis, however, have not been defined. This study attempts to assess the impact of such implants on clinical outcomes and the pattern of stent incorporation within the vessel wall. METHODS AND RESULTS Fifty-five balloon-expandable stents were implanted in 42 patients 6.1 +/- 4.7 years of age. Patients were followed prospectively (median, 15 months) and recatheterized 1 year after implantation. Thirty-eight patients had the implants positioned percutaneously (49 implants), while 4 patients (6 implants) had intraoperative implantations. There was a diameter increase in the stenotic area of 109 +/- 79% (P < .0001) and a gradient reduction of 74 +/- 26% (P < .0001). Twelve stents straddled the orifice of side-branch pulmonary arteries and reduced flow to the branch vessel acutely in 7 patients. Twenty-nine patients underwent recatheterization, and various degrees and locations of acquired intraluminal narrowing were observed in all cases, particularly in areas of diameter mismatch between the stented and nonstented vessels. Eleven patients had further dilation with diameter improvement. Of the 38 patients who underwent percutaneous implantation, planned surgery for pulmonary artery stenosis was avoided in 33 and deferred in 4 patients. One patient who was considered inoperable had stent implantation as a palliative procedure. Symptomatic improvement was reported in 27 patients, and 15 patients remained asymptomatic. CONCLUSIONS Endovascular stents have a role in the treatment of pulmonary artery stenoses and positively affect clinical care. The stenosis relief, however, may be tempered by the development of intraluminal stent obstruction, which may require redilation (15 of 55 stents) and mandates long-term follow-up.

Outcome of coronary artery aneurysms after kawasaki disease

From 1974 through 1991, a total of 583 children with Kawasaki disease were seen at the Hospital for Sick Children, in Toronto, of whom 80 (13.7%) had coronary artery involvement. There were 55 boys and 25 girls, whose mean age at onset was 2.9 +/- 2.5 years, followed for a mean period of 4.0 +/- 3.6 years. Giant aneurysms (maximum diameter > or = 8 mm) were found in 22 children, moderate-sized aneurysms (> or = 4 to < 8 mm) in 44, and dilation lesions (< 4 mm) in 14. Myocardial infarction occurred in 9 (1.5%), all of whom had giant aneurysms. The persistence rate for aneurysms was 72% at 1 year and 41% at 5 years of follow-up. In multivariate analysis, the regression of an aneurysm was significantly related to the severity of coronary artery lesions, initial treatment, and gender. Although > 80% of small or moderate-sized aneurysms regressed within 5 years, giant aneurysms did not regress during the follow-up period. In patients who received immune globulin therapy, coronary lesions tended to resolve more rapidly than in those treated with salicylate therapy alone, because 91% of the lesions in the former were small or moderate. These findings suggest that the severity of coronary artery involvement during the initial stages of Kawasaki disease influences the regression of these lesions, and that immune globulin treatment may improve outcome by reducing the incidence of severe lesions.

The modified Blalock-Taussig shunt: clinical impact and morbidity in Fallot's tetralogy in the current era.

BACKGROUND The Blalock-Taussig shunt is considered a low-risk management option for palliation in tetralogy of Fallot, but the morbidity associated with a Blalock-Taussig shunt can have a significant impact on patient care. We reviewed the outcome for this operation in the current era. METHODS Between 1990 and 1994, 65 children with tetralogy of Fallot received a modified Blalock-Taussig shunt. Sixty patients who had follow-up angiography were assessed for clinical outcomes and shunt-related morbidity and mortality. From the same study period, 68 of 247 pediatric patients who underwent angiography and tetralogy repair, but did not receive palliation, were randomly selected to comprise a comparison group. RESULTS Palliation was more likely in the presence of a complicated tetralogy malformation or if there was an associated medical condition. Median age at palliation was 58 days (range: 1 to 535 days). Ninety-five percent of shunts were right-sided. Self-limited morbidity complicated 11% of shunt operations. Significantly smaller distal right pulmonary arteries were observed in the palliated group before total repair compared with findings in the group without palliation and 33% of patients who underwent palliation had angiographic evidence of pulmonary artery distortion. Shunt stenosis was common and correlated with younger age at palliation. Shunt occlusion resulted in one death. Excluding noncardiac causes of death, overall survival was 90% in the palliated group versus 97% in the nonpalliated group (p = 0.09). CONCLUSIONS Pulmonary artery hypoplasia and angiographic evidence of pulmonary artery distortion are common after initial palliation by a modified Blalock-Taussig shunt. Neonatal palliation was associated with significantly smaller pulmonary arteries before repair, which necessitated additional interventions.

Balloon Angioplasty of Recurrent Coarctation: A 12-Year Review

OBJECTIVES This study was undertaken to investigate the long-term outcome of balloon angioplasty for recurrent coarctation of the aorta in a large series of patients. BACKGROUND Balloon angioplasty has become the standard treatment for residual or recurrent aortic coarctation. Despite the widespread use of this treatment modality, there are few data outlining the long-term outcome of a large patient cohort. METHODS Clinical, echocardiographic, hemodynamic and angiographic data on 90 consecutive patients who underwent balloon angioplasty between January 1984 and January 1996 were reviewed. RESULTS Mean systolic pressure gradients were reduced from 31 +/- 21 to 8 +/- 9 mm Hg after dilation (p = 0.0001). The mean diameter of the stenotic site, measured in the frontal and lateral views, increased by 38% and 35%, respectively (p = 0.001). Neurologic events occurred in two patients, with one death. An aortic tear occurred in one patient, requiring surgical intervention. Optimal results were defined as a postprocedure gradient < 20 mm Hg and were obtained acutely in 88% of patients. At long-term follow-up (12 years), 53 (72%) of 74 patients with an early optimal result remained free from reintervention. Transverse arch hypoplasia, defined as an arch dimension < 2 SD below the mean for age, was the primary predictor of the need for reintervention. CONCLUSIONS Although the majority of patients undergoing percutaneous balloon angioplasty for recoarctation of the aorta will achieve long-term benefit, the need for further surgical intervention in those with transverse arch hypoplasia remains high.