David A. Danford

Radiofrequency Catheter Ablation for Tachyarrhythmias in Children and Adolescents

Background Although radiofrequency catheter ablation has been used extensively to treat refractory supraventricular tachycardia in adults, few data are available on its safety and efficacy in children and adolescents. We reviewed registry data obtained from 24 centers to evaluate the indications, early results, complications, and short-term follow-up data in young patients who underwent this procedure. Methods Standardized data were submitted for 652 patients who underwent 725 procedures between January 1, 1991, and September 1, 1992. The mean length of follow-up was 13.5 months. Results The median age of the patients was 13.5 years, and 84 percent of them had structurally normal hearts. The initial success rates for ablation of atrioventricular accessory pathways (508 of 615 procedures) and atrioventricular-node reentry (63 of 76 procedures) were both 83 percent. Greater institutional experience in performing ablation in children and location of the accessory pathway in the left free wall correlated with...

Pediatric Radiofrequency Catheter Ablation Registry Success, Fluoroscopy Time, and Complication Rate for Supraventricular Tachycardia: Comparison of Early and Recent Eras

Ablation Outcomes for Supraventricular Tachycardia. Introduction: To assess changes of success rate, fluoroscopy time, and complication rate for six supraventricular tachycardia pathways/mechanisms, data from the Pediatric Radiofrequency Catheter Ablation Registry were grouped into two eras (1991–1995; 1996–1999).

Radiofrequency Catheter Ablation for Paroxysmal Supraventricular Tachycardia in Children and Adolescents Without Structural Heart Disease

Abstract Since 1990, management options available for children with paroxysmal supraventricular tachycardia (PSVT) have included radiofrequency catheter ablation (RCA). To determine the efficacy and safety of the procedure and to maintain a database for long-term follow-up, the Pediatric Electrophysiology Society began a Pediatric RCA Registry on January 1, 1991, to which 46 centers have submitted data from 4,135 total children and adolescents (patient age 0.1 to 20.9 years) who underwent 4,651 RCAs (through September 15, 1996). Of the 88% with a structurally normal heart, PSVT mechanisms (n = 4,030) included 3,110 accessory pathways and 920 atrioventricular node reentry tachycardia (AVNRT) during 3,653 procedures for 3,277 patients. During the 7 years of the Registry, analysis of indications for the procedure has shown a gradual shift. During the first year of the Registry for this PSVT group, “medically refractory tachycardia” was listed as the indication for 44% and “patient choice” was listed as 33%, compared with 29% and 58%, respectively, for the years 1995 to 1996 (p

Cardiovascular magnetic resonance myocardial feature tracking detects quantitative wall motion during dobutamine stress

BackgroundDobutamine stress cardiovascular magnetic resonance (DS-CMR) is an established tool to assess hibernating myocardium and ischemia. Analysis is typically based on visual assessment with considerable operator dependency. CMR myocardial feature tracking (CMR-FT) is a recently introduced technique for tissue voxel motion tracking on standard steady-state free precession (SSFP) images to derive circumferential and radial myocardial mechanics.We sought to determine the feasibility and reproducibility of CMR-FT for quantitative wall motion assessment during intermediate dose DS-CMR.Methods10 healthy subjects were studied at 1.5 Tesla. Myocardial strain parameters were derived from SSFP cine images using dedicated CMR-FT software (Diogenes MRI prototype; Tomtec; Germany). Right ventricular (RV) and left ventricular (LV) longitudinal strain (EllRV and EllLV) and LV long-axis radial strain (ErrLAX) were derived from a 4-chamber view at rest. LV short-axis circumferential strain (EccSAX) and ErrSAX; LV ejection fraction (EF) and volumes were analyzed at rest and during dobutamine stress (10 and 20 μg · kg-1· min-1).ResultsIn all volunteers strain parameters could be derived from the SSFP images at rest and stress. EccSAX values showed significantly increased contraction with DSMR (rest: -24.1 ± 6.7; 10 μg: -32.7 ± 11.4; 20 μg: -39.2 ± 15.2; p < 0.05). ErrSAX increased significantly with dobutamine (rest: 19.6 ± 14.6; 10 μg: 31.8 ± 20.9; 20 μg: 42.4 ± 25.5; p < 0.05). In parallel with these changes; EF increased significantly with dobutamine (rest: 56.9 ± 4.4%; 10 μg: 70.7 ± 8.1; 20 μg: 76.8 ± 4.6; p < 0.05). Observer variability was best for LV circumferential strain (EccSAX ) and worst for RV longitudinal strain (EllRV) as determined by 95% confidence intervals of the difference.ConclusionsCMR-FT reliably detects quantitative wall motion and strain derived from SSFP cine imaging that corresponds to inotropic stimulation. The current implementation may need improvement to reduce observer-induced variance. Within a given CMR lab; this novel technique holds promise of easy and fast quantification of wall mechanics and strain.

The learning curve for radiofrequency ablation of tachyarrhythmias in pediatric patients

The results of radiofrequency ablation for treatment of supraventricular tachyarrhythmias have been reported to improve with increasing experience; however, the precise nature of the learning curve in children is unknown. From November 1990 to October 1993, 1,546 consecutive procedures from the Pediatric Radiofrequency Ablation Registry were categorized into deciles based on number of prior pediatric procedures at the submitting institution. Negative exponential models were tested for strength of relation between volume of prior experience and 4 measures of outcome: success rate, complication rate, fluoroscopy time, and procedure time. Negative exponential curves described the experience-outcome relations well (r = 0.81 to 0.97). Learning rates were most rapid for successful ablation of left free wall accessory pathways, and slowest for right free wall pathway ablation. These models suggest that, given enough experience, procedural success rates > 90% (regardless of pathway location) and fluoroscopy and procedure times averaging < 40 minutes and 250 minutes, respectively, can be achieved in pediatric patients.

Pulmonary venous and systemic ventricular inflow obstruction in patients with congenital heart disease: Detection by combined two-dimensional and Doppler echocardiography

Obstruction to pulmonary venous return may be associated with a number of congenital cardiovascular abnormalities occurring both before and after surgery. Hemodynamic assessment by cardiac catheterization is often difficult. A noninvasive method for detection and quantitation of obstruction to systemic ventricular inflow would be clinically useful. Two-dimensionally directed pulsed and continuous wave Doppler echocardiography was performed before cardiac catheterization in 31 patients thought clinically to have possible obstruction to left ventricular inflow or pulmonary venous return. Primary diagnoses included transposition of the great arteries after the Mustard or Senning procedure in nine patients, total anomalous pulmonary venous connection in nine (in two after surgical repair), cor triatriatum in eight (in four after surgical repair), congenital mitral stenosis in four (in one after surgical repair) and mitral atresia in one. Severe obstruction was defined as a mean pressure gradient at catheterization of greater than or equal to 16 mm Hg at any level of the pulmonary venous return or of the systemic ventricular inflow. Severe obstruction was predicted if Doppler examination measured a flow velocity of greater than or equal to 2 m/s across any area of inflow obstruction. At catheterization, 12 patients (39%) had severe obstruction to left ventricular inflow or pulmonary venous return and all obstructions were correctly detected by Doppler echocardiography. The site of pulmonary venous obstruction was localized by two-dimensionally directed pulsed Doppler study. Patients with a lesser degree of obstruction had a lower Doppler velocity, but none had a maximal Doppler velocity of greater than or equal to 2 ms/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Color Doppler detection of multiple ventricular septal defects.

Combined two-dimensional and Doppler echocardiography has a high sensitivity and specificity for detection of isolated perimembranous ventricular septal defects. However, muscular or multiple ventricular septal defects may be difficult to diagnose with noninvasive methods, particularly in older children, necessitating angiography for accurate diagnosis. Detection of single and multiple ventricular septal defects with two-dimensional color flow mapping was compared with detection by standard two-dimensional imaging and Doppler. Both techniques were compared with four-chamber left ventricular angiography. Fifty-one patients (age 3 months to 25 years, mean 5.6 years) were studied. Eighteen had solitary ventricular septal defects, 18 had multiple ventricular septal defects, and 15 patients with intact ventricular septum served as a control group. At least one ventricular septal defect was detected by color Doppler and two-dimensional/Doppler methods in all patients with ventricular septal defect proved by angiography with no false positives. In the detection of multiple ventricular septal defects, the sensitivity of color Doppler was 72% and that of two-dimensional/Doppler was 38% (100% specificity in both). Color Doppler failed to identify multiple ventricular septal defects in five patients (two weighing less than 4 kg and three with reduced pulmonary blood flow). However, no large additional muscular defects were missed by imaging and color Doppler. Color Doppler is useful for the detection of ventricular septal defects and has higher sensitivity than two-dimensional/Doppler for multiple ventricular septal defects. The contribution of color Doppler appears to be in the detection of additional small muscular ventricular septal defects.

Spontaneous closure of the human fetal ductus arteriosus - A cause of fetal congestive heart failure

OBJECTIVE Closure of the fetal ductus arteriosus, which is usually due to nonsteroidal antiinflammatory agents, may be detrimental. Therefore prenatal and postnatal clinical and echocardiographic findings in four human fetuses with spontaneous ductus arteriosus occlusion are reported. STUDY DESIGN Echocardiographic and clinical data were retrospectively analyzed. RESULTS Spontaneous closure of the ductus arterious was discovered in four fetuses (gestational age 34 to 38 weeks). No mother had received nonsteroidal antiinflammatory agents. Enlargement of the right heart and pulmonary arteries and tricuspid and pulmonary regurgitation were present in all cases. Two fetuses had right ventricular hypertension. Postnatally their right ventricular function recovered promptly. The others had severe right heart failure with abnormal umbilical venous pulsations. After immediate delivery none had signs of persistent pulmonary hypertension. However, they have echocardiographic evidence of right ventricular dysfunction 2 to 6 months after delivery. CONCLUSIONS Occlusion of the fetal ductus arteriosus may also occur in the absence of treatment with nonsteroidal antiinflammatory agents. Immediate delivery resulted in good clinical outcome, although right ventricular dysfunction may persist.

Pacemakers in children: An update

This report reviews recent pacemaker technological advances as they apply to infants, children, and adolescents. Indications for pacemaker implantation in children have evolved since the 1984 Joint Task Force Guidelines. Recent data show that pacemaker implantation should be strongly considered in patients who have (1) asymptomatic congenital complete AV block with a mean heart rate less than 50 beats/min or other evidence of junctional instability; (2) congenital AV block with long QT interval; or (3) congenital long QT syndrome with bradyarrhythmias, or when conventional beta-blocker therapy is unsuccessful. Permanent pacemaker implantation is not necessarily an effective prophylactic measure against sudden death in patients following their operation who are receiving drug therapy for atrial tachyarrhythmias, and so is not absolutely indicated. New developments in lead technology have made transvenous lead systems more feasible for pediatric use. Because epicardial leads are required for small infants and for cosmetic reasons in some older children, design improvements are needed to enhance epicardial lead performance. Rate-responsive pacing is an acceptable alternative to dual-chamber pacing for augmenting exercise tolerance, and for children with sinus node dysfunction it is the preferred pacing mode. Pacemakers with automatic antitachycardia capabilities and with noninvasive electrophysiology features are valuable in children with atrial tachyarrhythmias. New data suggest that chronic atrial pacing also may be effective in controlling atrial tachyarrhythmias. New developments in pacemaker systems for the young parallel those for the older population, but differences between adult and pediatric patients demand ongoing increased participation by pediatric cardiologists.

Long-term (5- to 20-year) outcomes after transcatheter or surgical treatment of hemodynamically significant isolated secundum atrial septal defect

Truly long-term follow-up data after transcatheter closure (TC) of atrial septal defects (ASDs) are scarce. We report the 5- to 20-year outcomes of TC and surgical closure (SC) for typical secundum ASD. We reviewed the records of patients with isolated secundum ASD and right ventricular volume overload who underwent TC or SC (January 1, 1986 to September 30, 2005). Follow-up was obtained through a combination of chart review, physician records, and telephone survey. We identified 375 patients (207 SC and 168 TC) and obtained follow-up data >5 years (median follow-up 10 years) for 300 (152 SC, 148 TC). Nine patients have died (3%). The New York Heart Association functional class was unchanged in 227 patients, improved in 25, and was worse in 15. Clinically significant arrhythmia was found in 28 patients (9.3%); 21% aged >40 years developed arrhythmia. On multivariate analysis, the odds of significant arrhythmia tended to be greater in the SC group, but this was statistically insignificant (95% confidence interval 0.68 to 3.9, p = 0.27). Age and preprocedure arrhythmia, but not TC or SC, were independent risk factors for late arrhythmia (p <0.001). No difference was found in the incidence of late, probably embolic, stroke in the TC (3%) versus SC (2%) groups. In conclusion, long-term outcomes after secundum ASD closure using modern methods are excellent. No significant differences were found between TC versus SC with regard to survival, functional capacity, atrial arrhythmias, or embolic neurologic events. Arrhythmia and neurologic events remain long-term risks after ASD closure, especially if the patient had pre-existing arrhythmia.