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Biomedical subjects

Edward P Walsh

Publications and source records attributed to Edward P Walsh.

At least 19 recordsLinked to original sources
PubMed2006

Transvenous pacing leads and systemic thromboemboli in patients with intracardiac shunts: a multicenter study.

BACKGROUND: The risk of systemic thromboemboli associated with transvenous leads in the presence of an intracardiac shunt is currently unknown. METHODS AND RESULTS: To define this risk, we conducted a multicenter, retrospective cohort study of 202 patients with intracardiac shunts: Sixty-four had transvenous leads (group 1), 56 had epicardial leads (group 2), and 82 had right-to-left shunts but no pacemaker or implantable cardioverter defibrillator leads (group 3). Patient-years were accrued until the occurrence of systemic thromboemboli or study termination. Censoring occurred in the event of complete shunt closure, death, or loss to follow-up. Mean ages for groups 1, 2, and 3 were 33.9+/-18.0, 22.2+/-12.6, and 22.9+/-15.0 years, respectively. Respective oxygen saturations were 91.2+/-9.1%, 88.1+/-8.1%, and 79.7+/-6.7%. During respective median follow-ups of 7.3, 9.3, and 17.0 years, 24 patients had at least 1 systemic thromboembolus: 10 (15.6%), 5 (8.9%), and 9 (11.0%) in groups 1, 2, and 3, respectively. Univariate risk factors were older age (hazard ratio [HR], 1.05; P=0.0001), ongoing phlebotomy (HR, 3.1; P=0.0415), and an transvenous lead (HR, 2.4; P=0.0421). In multivariate, stepwise regression analyses, transvenous leads remained an independent predictor of systemic thromboemboli (HR, 2.6; P=0.0265). In patients with transvenous leads, independent risk factors were older age (HR, 1.05; P=0.0080), atrial fibrillation or flutter (HR, 6.7; P=0.0214), and ongoing phlebotomy (HR, 14.4; P=0.0349). Having had aspirin or warfarin prescribed was not protective. Epicardial leads were, however, associated with higher atrial (P=0.0407) and ventricular (P=0.0270) thresholds and shorter generator longevity (HR, 1.9; P=0.0176). CONCLUSIONS: Transvenous leads incur a >2-fold increased risk of systemic thromboemboli in patients with intracardiac shunts.

Arteriovenous Shunt, Surgical↗
PubMed2006

Cryoablation for accessory pathways located near normal conduction tissues or within the coronary venous system in children and young adults.

BACKGROUND: Cryoablation may offer advantages over radiofrequency (RF) ablation for certain arrhythmia substrates, such as septal accessory pathways (APs). Data for young patients, especially regarding recurrence risk, require expansion. OBJECTIVES: The purpose of this study was to study institutional outcomes for cryoablation of APs located in potentially difficult septal regions for children and young adults. METHODS: Cryoablation was attempted in 35 young patients (mean age 15.6 years) with 37 APs that were either close to normal conduction tissues or inside the coronary venous system. Outcomes were compared with previously published institutional data for RF ablation at these same locations. RESULTS: Acute cryoablation success was achieved for 29 (78%) of 37 APs. Apart from permanent PR prolongation in one case and right bundle branch block in one other, there were no detrimental effects on normal conduction. At median follow-up of 207 days (range 2-695 days), AP conduction recurred for 13 (45%) of 29 ablated APs. Younger patient age and midseptal AP location correlated with higher likelihood of recurrence. Acute success rates for cryoablation were similar to RF ablation in our laboratory, but recurrence rates were significantly higher (P <.001). CONCLUSION: Cryoablation yields acute success rates comparable with RF ablation for difficult septal APs in young patients. The risk of AP recurrence appears higher after cryoablation, although safety benefits may provide suitable compensation for this deficiency. Methods for creating more effective cryoablation lesions need to be explored.

Adolescent↗
PubMed2006

Ablation of nonautomatic focal atrial tachycardia in children and adults with congenital heart disease.

INTRODUCTION: Nonautomatic focal atrial tachycardia (NAFAT) has been characterized in adults with structurally normal hearts. This article characterizes NAFAT in a population of patients with complex congenital heart disease. METHODS AND RESULTS: Electrophysiologic and electroanatomic mapping data and acute outcomes were reviewed in patients undergoing mapping and ablative procedures for atrial tachycardia at Children's Hospital, Boston, between January 1999 and December 2003. Twenty-two NAFAT foci were identified in 17 patients out of 216 patients studied. Fourteen of these 17 patients had congenital heart disease. The average age of the patients with a NAFAT mechanism was 27 years and there was no gender predilection. The presumptive diagnosis based on clinical grounds and surface ECG assessment in 11 of 17 patients with NAFAT was atrial flutter. None of the 17 patients were suspected of having a NAFAT mechanism by noninvasive assessment. Four of the 10 patients had both NAFAT and macroreentrant atrial tachycardias. NAFAT cycle lengths varied widely (200-680 ms) between patients. Sixteen of the 22 NAFAT foci were mapped to the anatomic right atrium (RA). Acute ablative success was achieved in 17 out of 22 foci (77%). CONCLUSION: NAFAT is relatively uncommon in a pediatric tertiary care setting, and in that setting occurs most often in adults with congenital heart disease. NAFAT is indistinguishable from other forms of atrial tachycardia by noninvasive means and can mimic other forms of atrial tachycardia on electrocardiogram. The foci were predominantly found in the RA and were, in most cases, acutely amenable to catheter ablation therapy.

Adolescent↗
PubMed2006

Age, size, and lead factors alone do not predict venous obstruction in children and young adults with transvenous lead systems.

BACKGROUND: Venous occlusion is a recognized complication of transvenous pacing, and lead cross-sectional area indexed to body surface area (BSA) has been used to predict venous obstruction in children. OBJECTIVE: The aim of this study was to identify the risk factors and incidence of angiographic venous obstruction after transvenous lead implantation in both children and young adults. METHODS: Contrast venography was obtained in 85 of 90 consecutive patients undergoing repeat pacemaker or ICD procedures from 2002 to 2004 at a single cardiac center. Venograms were graded as complete venous obstruction, significant partial obstruction (>70% with collaterals), or patent. RESULTS: The cohort had a median age of 15.0 years at implant and was divided into two age groups: 3-12 years (n = 35) and 13 years and over (n = 50). After a median interval of 6.5 years, complete obstruction was seen in 11 of 85 patients (13%) and partial obstruction in another 10 patients (12%). No significant differences were seen in the incidence of obstruction between the two age groups although younger patients had a larger lead indexed to BSA ratio (6.82 vs 5.05, P = 0.005). There were no significant differences between obstructed and nonobstructed patients in relation to age, size, growth, or lead factors. CONCLUSION: Transvenous lead systems implanted in young children have a similar incidence of venous occlusion compared to older patients. Furthermore, patient age, body size, and lead characteristics at implant do not clearly predict venous occlusion.

Adolescent↗
PubMed2006

Cardiac conduction through engineered tissue.

In children, interruption of cardiac atrioventricular (AV) electrical conduction can result from congenital defects, surgical interventions, and maternal autoimmune diseases during pregnancy. Complete AV conduction block is typically treated by implanting an electronic pacemaker device, although long-term pacing therapy in pediatric patients has significant complications. As a first step toward developing a substitute treatment, we implanted engineered tissue constructs in rat hearts to create an alternative AV conduction pathway. We found that skeletal muscle-derived cells in the constructs exhibited sustained electrical coupling through persistent expression and function of gap junction proteins. Using fluorescence in situ hybridization and polymerase chain reaction analyses, myogenic cells in the constructs were shown to survive in the AV groove of implanted hearts for the duration of the animal's natural life. Perfusion of hearts with fluorescently labeled lec-tin demonstrated that implanted tissues became vascularized and immunostaining verified the presence of proteins important in electromechanical integration of myogenic cells with surrounding re-cipient rat cardiomyocytes. Finally, using optical mapping and electrophysiological analyses, we provide evidence of permanent AV conduction through the implant in one-third of recipient animals. Our experiments provide a proof-of-principle that engineered tissue constructs can function as an electrical conduit and, ultimately, may offer a substitute treatment to conventional pacing therapy.

Animals↗
PubMed2005

Comparison of modern steroid-eluting epicardial and thin transvenous pacemaker leads in pediatric and congenital heart disease patients.

OBJECTIVE: Optimal pacemaker lead choice in pediatric patients eligible for either epicardial or transvenous leads remains unclear. We compared performances of modern thin transvenous (TTV) and steroid-eluting epicardial (SEE) leads in patients followed at one pediatric center. METHODS: Retrospective review of patients with qualifying leads implanted from August 1997 to March 2004. Threshold energy (TE) at implant and follow-up, sensing thresholds, lead complications, and repeat pacing-related procedures were analyzed. Lead performances were compared using t-tests, Wilcoxon rank-sum tests and Cox regression. Survival curves were plotted using Kaplan-Meier analysis. RESULTS: A total of 370 implant procedures, 521 leads, and 1549 visits were evaluated. In all, 256 leads were SEE (49%, 184 implants) and 265 were TTV (51%, 186 implants). Median follow-up was 29 months (range 1-80 months). Patients with SEE systems were younger at implant (6 vs. 17 yrs, p < 0.001), and more had congenital heart defects (82% vs. 57%, p < 0.001). At follow-up, ventricular TEs were higher for SEE leads at implant (p < 0.001), 1 month (p < 0.001), and up to 4 years (p = 0.019). When compared across all follow-up durations combined, TTV TEs were significantly lower than SEE TEs for both atrial and ventricular leads (p < 0.001). A total of 70 repeat procedures were performed in 60 patients during the study period, which comprised 18% of SEE and 14% of TTV system patients (p = NS). In all, 18 TTV and 19 SEE leads failed (p = NS). Estimated freedom from lead failure at 1, 3, and 5 years was 97%, 88%, 85% for TTV leads and 96%, 92%, and 58% for SEE leads (log rank P = NS). CONCLUSIONS: Both SEE and TTV leads showed good mid-term performance and survival in our cohort. Higher TEs seen for SEE leads, especially ventricular and unipolar leads, may result in higher current drain and thus more generator replacements than TTV systems. Lead failure rates were comparable across lead types. TTV leads offer a promising alternative to SEE systems in terms of performance for young patients without intracardiac shunting who do not require open-chest surgery for another indication.

Adolescent↗
PubMed2005

Prospective trial of electroanatomically guided, irrigated catheter ablation of atrial tachycardia in patients with congenital heart disease.

BACKGROUND: Ablation success rates reported for atrial tachycardia (AT) patients with congenital heart disease (CHD) is lower than the rates reported for other varieties of supraventricular tachycardia. Retrospective studies suggest these rates might be increased by the use of irrigated radiofrequency (RF) ablation. OBJECTIVES: The purpose of this study was to determine whether irrigated RF ablation increases ablation success rates in patients with CHD and AT. METHODS: Patients were studied in a prospective, randomized, nonblinded manner. The operator was limited to use of randomized therapy (standard or irrigated ablation) for the first 6 minutes of RF application to each targeted arrhythmia. Lesion characteristics were recorded, and acute ablation success was ascertained. Structured clinical follow-up was performed over a 6-month period. RESULTS: Forty-seven ATs were targeted in 26 patients; 72% of these ATs were ablated. Within the 6-minute randomization period, no difference in success rates of standard and irrigated catheters was noted. However, crossover from standard to irrigated ablation more likely was successful than vice versa (irrigated: 8 successes/8 attempts vs standard: 1 success/4 attempts, P = .018), and overall success was greater using irrigated catheters (66% vs 33%, P = .019). Mean delivered power was slightly higher in irrigated lesions (32.5 W vs 30.2 W, P = .025), and mean temperature was much lower (33.5 degrees C vs 59.3 degrees C, P < .001). A composite AT intensity score was significantly reduced compared with preablation values at 6-month follow-up of all patients. CONCLUSIONS: Ablation of ATs in patients with CHD results in symptomatic improvement over short-term follow-up. Irrigated ablation may result in higher acute success rates in these patients.

Adolescent↗
PubMed2005

First appropriate use of automated external defibrillator in an infant.

Automated external defibrillators (AEDs) are currently not recommended for use in children under 1 year of age. We report the first description of successful AED defibrillation in an infant using a 50 J shock and provide rationale for employing these life-saving devices in infants at risk for sudden cardiac death.

Defibrillators↗
PubMed2005

Utility of routine follow-up defibrillator threshold testing in congenital heart disease and pediatric populations.

INTRODUCTION: Recent studies have suggested that routine defibrillation threshold (DFT) testing of implantable cardioverter defibrillators (ICDs) in adults may not be necessary. The congenital heart disease and pediatric populations are a unique group of ICD recipients having a higher incidence of lead failure. We investigated the utility of follow-up DFT testing in this population. METHODS AND RESULTS: The records of 155 ICD recipients at one center were retrospectively reviewed, and patients having one or more follow-up DFT tests were analyzed. The patients were divided into two groups. The "routine" group consisted of 58 follow-up DFT procedures in 46 patients, without known changes in ICD parameters. The "prompted" group consisted of 21 follow-up DFT procedures in 18 patients, motivated by clinical concerns about changes in ICD lead status. Of 58 "routine" DFTs performed at a mean postimplant duration of 32 +/- 23 months (range 2-78), 7 (12%) had reprogramming, and 1 required a hardware change as a result of the testing. Of the 21 "prompted" DFTs performed, 7 required device reprogramming, and 3 required hardware upgrade. Overall, 19 (24%) of 79 procedures detected clinically significant changes, requiring reprogramming or ICD system revision. No complications were seen from follow-up DFT testing. CONCLUSION: A high rate of abnormalities was found at follow-up DFT testing in this population, especially in the group of patients with clinically prompted testing. Clinically indicated DFT testing, as expected, has a high yield of important information on device function in congenital heart disease and pediatric populations.

Adolescent↗
PubMed2005

Anesthetic management of the neonate with congenital complete heart block: a 16-year review.

BACKGROUND: Anesthesia for patients with complete heart block can be associated with significant hemodynamic instability. The aim of this study is to review our anesthetic experience of neonates with congenital complete heart block (CCHB) who underwent placement of either a temporary epicardial pacing system or a permanent epicardial pacemaker. METHODS: The anesthetic management of neonates with CCHB who underwent pacemaker placement at a single institution over a 16-year period was reviewed. RESULTS: Twenty-four neonates were identified, 17 with a structurally normal heart (NL) and seven with associated congenital heart defects (CHD). Median (range) gestational age was 36.9 (26-41) weeks, birth weight 2.9 (1.0-4.1) kg, and baseline heart rate 47 (38-80) b.min(-1). A temporary epicardial pacing system was placed in six patients (four CHD, two NL; P = 0.003) following institution of mechanical ventilation and inotropic support for a low cardiac output state, and a permanent epicardial pacemaker was placed in 18 patients. Atropine 0.02 mg.kg(-1) IV prior to induction (n = 5) increased heart rate less than 20%. Intraoperative hypotension was documented in nine neonates, five of seven with CHD and four of 17 with NL (P = 0.02). In four patients (44%) hypotension occurred despite concurrent inotropic support. Intraoperative cardiac arrest occurred in one neonate, necessitating institution of extracorporeal membrane oxygenation. Two patients (8.3%) died in hospital from complex CHD and complications of prematurity. CONCLUSIONS: Early institution of mechanical ventilation, inotropic support and pacing are necessary in the neonate with CCHB and poor hemodynamic function, particularly with coexisting CHD or prematurity.

Anesthesia↗
PubMed2004

Relation of right ventricular pacing in tetralogy of Fallot to electrical resynchronization.

Prolonged QRS duration is a marker of increased sudden death risk in tetralogy of Fallot. Right ventricular pacing increased QRS duration in this population and could be counteracted with optimization of the atrioventricular interval in a subset of patients, potentially offering right ventricular resynchronization in patients with baseline right bundle branch block. Effective pacing therapy may require site-specific placement of pacing leads and precise pacemaker programming.

Adult↗
PubMed2004

Value of programmed ventricular stimulation after tetralogy of fallot repair: a multicenter study.

BACKGROUND: Studies have consistently shown that ventricular tachycardia (VT) and sudden cardiac death (SCD) complicate the long-term outcome after tetralogy of Fallot repair, yet the diagnostic and predictive value of electrophysiological testing in this population is uncertain. METHODS AND RESULTS: A multicenter cohort of 252 patients with repaired tetralogy of Fallot undergoing programmed ventricular stimulation was followed up for 18.5+/-9.6 and 6.5+/-4.5 years after corrective surgery and electrophysiological testing, respectively. Clinical VT and/or SCD occurred in 24.6%. Sustained monomorphic VT and polymorphic VT were induced in 30.2% and 4.4%. Including polymorphic VT in the definition of inducibility improved sensitivity (66.1+/-6.0% versus 77.4+/-5.3%, P=0.0082) with a marginal reduction in specificity (81.6+/-2.8% versus 79.5+/-2.9%, P=0.0455). Positive and negative predictive values were 55.2+/-5.3% and 91.5+/-2.2%. Independent risk factors for inducibility were age at study > or =18 years (OR, 3.3), palpitations (OR, 2.8), prior palliative surgery (OR, 3.1), modified Lown criteria > or =2 (OR, 5.6), and cardiothoracic ratio > or =0.6 (OR, 3.3). Event-free survival rates in noninducible and inducible patients at 1, 5, 10, and 15 years were 97.9%, 92.8%, 89.3%, and 89.3% versus 79.4%, 62.6%, 58.7%, and 50.3%, respectively (P<0.0001). Both inducible monomorphic VT [relative risk (RR), 5.0; P=0.0002] and polymorphic VT (RR, 12.9; P<0.0001) predicted future clinical VT and SCD. In a multivariate analysis, inducible sustained VT was an independent risk factor for subsequent events (RR, 4.7; 95% CI, 1.2 to 18.5; P=0.0268). CONCLUSIONS: Programmed ventricular stimulation is of diagnostic and prognostic value in risk stratifying patients with repaired tetralogy of Fallot. In this patient population, inducible sustained polymorphic VT should not be disregarded as nonspecific.

Adolescent↗
PubMed2004

Psychosocial factors and quality of life in children and adolescents with implantable cardioverter-defibrillators.

Few data exist on the quality of life in children and adolescents with implantable cardioverter-defibrillators (ICDs). The objective of this study was to determine whether anxiety, depression, family functioning, and quality of life are related to cardiac illness severity in pediatric patients with ICDs. The subjects were 20 patients (mean age 14.8 years; median 15.1, range 9 to 19) who had an ICD implantation a mean 1.4 years (median 0.1, range 0 to 6) before the study. The patients completed the Revised Children's Manifest Anxiety Scale, Reynold's Adolescent/Child Depression Scales, Child Health Questionnaire-87, and the Worries About ICDs Scale. The parents completed the Impact-on-Family Scale and the Child Health Questionnaire (CHQ-50). The Defibrillator Severity Index assessed cardiac severity. The rates of anxiety or depression were not increased, although the patients appeared to experience a greater need for social acceptance. Parent ratings of overall family functioning did not differ significantly from normative sample means. Parents reported significantly lower CHQ-50 summary physical functioning scores than scores of a normative United States sample, whereas there was no significant difference for the CHQ-50 summary psychosocial score. Caregivers perceived that their children had a lower quality of life when asked about their child's physical functioning, functioning in the social-physical role, and general health perceptions. Despite the overall nonsignificance of the psychosocial summary score, the social emotional/behavioral role, and the emotional impact their child's health had on themselves, subscales were all significantly lower than the normative sample. Cardiac illness severity was not significantly associated with anxiety, depression, quality of life, or family functioning. However, significant associations were found among measures of anxiety, depression, family functioning, and quality of life. Overall, most pediatric patients with ICDs appear to be a resilient group of youngsters. Their quality of life was more strongly correlated with their feelings of anxiety and depression as well as their family functioning than to the severity of their cardiac illness.

Adolescent↗
PubMed2004

Patient, procedural, and hardware factors associated with pacemaker lead failures in pediatrics and congenital heart disease.

OBJECTIVES: To examine outcomes of children with pacemakers over a 22-year period and identify risk factors for lead failure. BACKGROUND: Small patient size, structural cardiac abnormalities, and growth may complicate pediatric pacemaker management. Better knowledge of risk factors for lead failure in these patients may help improve future outcomes. METHODS: All pacemaker patients followed at one pediatric center 1980-2002 were included. Lead failures were identified retrospectively as leads repaired, replaced, or abandoned due to fracture, insulation break, dislodgement, or abnormalities in pacing or sensing. Risk factors were identified using logistic regression and Cox analyses. RESULTS: A total of 1007 leads were implanted in 497 patients during the study period (5175 lead-years). Median age at implant was 9 years (0-55); 64% of patients had structural congenital heart disease. Median follow-up time was 6.2 years (0-22). Lead failure occurred in 155 leads (15%), and 115 patients (23%), with 28% of patients experiencing multiple failures. Significant independent correlates of lead failure included age <12 years at implant, history of structural congenital heart defects, and epicardial lead placement. Younger patients (<12 years) experienced significantly more lead fractures than older children (P = .005), while patients with congenital heart defects experienced more exit block. Epicardial leads were more likely to fail due to fracture or exit block, while transvenous leads failed more due to insulation breaks or dislodgements. CONCLUSIONS: Pediatric pacing patients have a high incidence lead failures. These occur most commonly in younger patients, structural congenital heart disease, and those with epicardial lead systems. Approaches to pacing system implantation and follow-up in these patients need to be individualized, with special attention to minimizing risk of lead failures. Our findings suggest that expanded utilization of transvenous systems in smaller patients seems justified when anatomy permits.

Adolescent↗