Frank Zimmerman

Acute hemodynamic benefit of multisite ventricular pacing after congenital heart surgery.

BACKGROUND Cardiac dysfunction after congenital heart surgery is a major cause of morbidity and mortality. Cardiac resynchronization through multisite ventricular pacing (MSVP) improves cardiac index and ventricular function, and lowers systemic vascular resistance (SVR) in adults with heart failure and interventricular conduction delay. METHODS The acute hemodynamic effects of MSVP after congenital heart surgery were assessed. Twenty-nine patients (aged 1 week to 17 years) with prolonged QRS interval had atrial and ventricular unipolar epicardial temporary pacing leads placed at surgery. Group 1 consisted of patients with a single ventricle (n = 14); group 2 included patients with two-ventricle anatomy (tetralogy of Fallot, ventricular septal defect) undergoing ventricular surgery (n = 10); and group 3 included patients with two-ventricle anatomy undergoing other cardiac surgery (n = 5). At a mean postoperative day 1 (range, 0 to 6), blood pressure, systemic and mixed venous oxygen saturations, electrocardiograms, and echocardiograms were obtained before and after 20 minutes of MSVP. RESULTS The QRS duration decreased with MSVP in all patients (mean, 23%, p < 0.005). Systolic blood pressure improved in all patients (mean, 9.7%, p < 0.005). Cardiac index improved in 19 of 21 patients tested, with no change in 2 patients (mean, 15.1%, p = 0.0001). In 2 patients, MSVP facilitated weaning from cardiopulmonary bypass. Echocardiographic mitral or tricuspid valve inflow was not significantly different with MSVP. CONCLUSIONS Multisite ventricular pacing results in improved cardiac index and increased systolic blood pressure, and it can also facilitate weaning from cardiopulmonary bypass. Multisite ventricular pacing may be used as adjunct to standard postoperative treatment of cardiac dysfunction after congenital heart surgery.

Daily sedative interruption in mechanically ventilated patients at risk for coronary artery disease.

Objectives:To determine the prevalence of myocardial ischemia in mechanically ventilated patients with coronary risk factors and compare periods of sedative interruption vs. sedative infusion. Design:Prospective, blinded observational study. Setting:Medical intensive care unit of tertiary care medical center. Patients:Intubated, mechanically ventilated patients with established coronary artery disease risk factors. Interventions:Continuous three-lead Holter monitors with ST-segment analysis by a blinded cardiologist were used to detect myocardial ischemia. Ischemia was defined as ST-segment elevation or depression of >0.1 mV from baseline. Measurements and Main Results:Comparisons between periods of awakening from sedation vs. sedative infusion were made. Vital signs, catecholamine levels, and time with ischemia detected by Holter monitor during the two periods were compared. Heart rate, mean arterial pressure, rate–pressure product, respiratory rate, and catecholamine levels were all significantly higher during sedative interruption. Eighteen of 74 patients (24%) demonstrated ischemic changes. Patients with myocardial ischemia had a longer intensive care unit length of stay (17.4 ± 17.5 vs. 9.6 ± 6.7 days, p = .04). Despite changes in vital signs and catecholamine levels during sedative interruption, fraction of ischemic time did not differ between the time awake vs. time sedated [median [interquartile range] of 0% [0, 0] compared with 0% [0, 0] while they were sedated [p = .17]). The finding of similar fractions of ischemic time between awake and sedated states persisted with analysis of the subgroup of 18 patients with ischemia. Conclusions:Myocardial ischemia is common in critically ill mechanically ventilated patients with coronary artery disease risk factors. Daily sedative interruption is not associated with an increased occurrence of myocardial ischemia in these patients.

Heart block and empirical therapy after transcatheter closure of perimembranous ventricular septal defect

Two patients with perimembranous ventricular septal defects (VSDs) and inlet extension have undergone uncomplicated transcatheter device closure using the Amplatzer membranous VSD device. Both patients developed complete heart block 2–4 days from the closure. Both patients responded well to high‐dose intravenous therapy with steroids and high‐dose oral anti‐inflammatory aspirin. Both patients remain in normal sinus rhythm 8 weeks and 10 months, respectively, from the episode.

PACES/HRS Expert Consensus Statement on the Evaluation and Management of Ventricular Arrhythmias in the Child With a Structurally Normal Heart

and Management of Ventricular Arrhythmias in the Child With a Structurally Normal Heart Jane E. Crosson, MD, FACC (Chair), David J. Callans, MD, FHRS, FACC, FAHA (Chair), David J. Bradley, MD, FACC, FAAP, Anne Dubin, MD, FHRS, FAHA, FACC, Michael Epstein, MD, FACC, CCDC, Susan Etheridge, MD, FHRS, FACC, FAAP, CEPS, Andrew Papez, MD, FHRS, CCDS, John R. Phillips, MD, FAAP, FHRS, FACC, Larry A. Rhodes, MD, FAAP, FHRS, FACC, Philip Saul, MD, FHRS, FACC, FAHA, Elizabeth Stephenson, MD, MSc, FHRS, CCDS, CEPS, William Stevenson, MD, FAHA, FHRS, FACC, Frank Zimmerman, MD, FAHA, FHRS From the Bloomberg Children’s Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, C.S. Mott Children’s Hospital, Anne Arbor, Michigan, Lucile Packard Children’s Hospital, Stanford School of Medicine, Stanford, California, Maine Medical Center, Portland, Maine, University of Utah and Primary Children’s Medical Center, Salt Lake City, Utah, Phoenix Children’s Hospital/Arizona Pediatric Cardiology Consultants Phoenix, Arizona, WVUH Children’s Hospital, Morgantown, West Virginia, Nationwide Children’s Hospital, Ohio State University, Columbus, Ohio, University of Toronto, Toronto, Ontario, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, and Advocate Heart Institute for Children Advocate Children’s Hospital, Oak Lawn, Illinois.

Managed Ventricular Pacing in Pediatric Patients and Patients With Congenital Heart Disease

Ventricular dyssynchrony induced by ventricular pacing (VP) may predispose patients to congestive heart failure. The detrimental effects of VP are directly related to the cumulative percentage of VP (Cum%VP). Managed VP (MVP) is a novel pacing algorithm developed to minimize unnecessary VP by uncoupling atrial pacing from VP. This retrospective analysis assessed the feasibility of using MVP in pediatric patients and patients with congenital heart disease (CHD). A multicenter review evaluated all pediatric patients <22 years old and older patients with CHD that had an implanted device using a MVP algorithm. Primary outcome variables were Cum%VP and adverse events. A subgroup analysis evaluated patients that had a DDD(R) pacemaker before a MVP device and compared Cum%VP before and after initiation of MVP. From 6 centers 62 patients (mean age 21.5 +/- 9.6 years) were included; 64% had CHD. With a MVP device, mean Cum%VP was 4.3 +/- 14.6% (range 0 to 83.7): Eleven patients were eligible for subgroup analysis. Compared with DDD(R), Cum%VP significantly decreased with MVP (67.1 +/- 29.4% vs 9.2 +/- 24.8%, p = 0.002). One MVP-related adverse event occurred; a patient with intermittent atrioventricular block had symptoms with frequent nonconducted atrial depolarizations and was reprogrammed to DDD. In conclusion, MVP can be used safely and can significantly reduce unnecessary VP in pediatric patients and patients with CHD.

Real-Time Three-Dimensional Echocardiographic Assessment of Left Ventricular Systolic Dyssynchrony in Healthy Children

BACKGROUND The use of resynchronization therapy for the treatment of left ventricular (LV) systolic dysfunction in children has been expanding. Because QRS duration is not a reliable indicator of the presence or severity of dyssynchrony in every case, additional methods of quantitation of dyssynchrony are needed. The purpose of this study was threefold: (1) to define normal values for LV real-time quantitative three-dimensional echocardiographic (3DE) dyssynchrony indices (DIs), (2) to analyze the feasibility and observer variability of 3DE DIs in a wide range of children, and (3) to determine the effects of age, heart rate, body surface area, and LV end-diastolic volume on these parameters. METHODS The two specific parameters studied were the standard deviation of the time to minimum systolic volume for the number of segments analyzed and the time difference between the earliest and latest contracting segments. Both parameters were expressed as a percentage of the cardiac cycle length. RESULTS In 125 normal children aged 1 day to 19 years, adequate dyssynchrony studies were obtained in 102 (81.8%). The mean LV 3DE DIs expressed as the standard deviation of the time to minimum systolic volume for the number of segments analyzed were 1.16 ± 0.58 for 16 segments, 1.01 ± 0.60 for 12 segments, and 0.93 ± 0.68 for 6 segments. The mean LV 3DE DIs expressed as the time difference between the earliest and latest contracting segments were 3.80 ± 1.57 for 16 segments, 2.99 ± 1.42 for 12 segments, and 2.27 ± 1.35 for 6 segments. There were no effects of age, heart rate, body surface area, or LV end-diastolic volume on 3DE DIs. Intraobserver variability was 5.1%, and interobserver variability was 7.6%. CONCLUSION Three-dimensional echocardiographic DI analysis is reproducible and feasible in most children. Three-dimensional echocardiographic DIs are not affected by growth-related parameters in children but are lower than previously reported adult values.

Chiari Drop Attacks: Surgical Decompression and the Role of Tilt Table Testing

Background: Chiari I malformation (CM1) is characterized by impaired CSF flow through the foramen magnum. Dysfunctional autonomic cardiovascular regulation may result in syncope. Syncope may be the primary presenting symptom of CM1: a syndrome termed Chiari drop attack. It has been postulated that Chiari drop attack is secondary to dysautonomia caused by hindbrain compression. There has been recent debate regarding the association between CM1, dysautonomia and Chiari drop attack. Methods: We selected patients with Chiari drop attacks who had negative workups for cardiac syncope, followed by tilt table testing and subsequent surgical decompression. We report test results and clinical outcomes following CM1 decompression. Results: Ten patients met the inclusion criteria: 5 patients had positive and 5 negative tilt table tests. Following decompression, 7 had symptomatic improvement or resolution and 3 failed to improve. The sensitivity and specificity of the tilt table test for detecting clinical improvement with surgical decompression was 43 and 33%, respectively. Tilt table testing had 40% accuracy in predicting clinical response to decompression. Conclusions: In this short series, surgical decompression of CM1 has a high success rate (70%) for patients with Chiari drop attacks. Tilt table testing has poor predictive value in judging the clinical response to surgical decompression and is not a useful test to guide surgical decision- making.

Ventricular pacing in single ventricles—A bad combination

BACKGROUND Chronic ventricular pacing (VP) is associated with systolic dysfunction in a subset of pediatric patients with heart block and structurally normal hearts. The effect of chronic VP in congenital heart disease is less well understood, specifically in the single-ventricle (SV) population. OBJECTIVE To determine the longitudinal effect of VP in SV patients. METHODS SV patients with heart block and dual-chamber pacemakers requiring >50% VP were compared with nonpaced (controls) SV patients matched for age, sex, and SV morphology. Patients were excluded if a prepacing echocardiogram was not available. Echocardiogram and clinical parameters were compared at baseline (prepacing) and at last follow-up in the paced group, and in controls when they were at ages similar to those of their paced-group matches. RESULTS Twenty-two paced and 53 control patients from 2 institutions were followed for similar durations (6.6±5 years vs 7.6±7.6 years; P = .59). There was no difference between groups regarding baseline ventricular function or the presence of moderate-to-severe atrioventricular valvar regurgitation (AVVR). Paced patients were more likely to develop moderate-to-severe systolic dysfunction (68% vs 15%; P < .01) and AVVR (55% vs 8%; P < .001) and require heart failure medications (65% vs 21%; P < .001). Chronic VP was also associated with a higher risk of transplantation or death (odds ratio, 4.9; 95% confidence interval, 1.05-22.7; P = .04). CONCLUSIONS SV patients requiring chronic VP are at higher risk of developing moderate-to-severe ventricular dysfunction and AVVR with an increased risk of death or transplantation compared with controls. New strategies to either limit VP or improve synchronization in this vulnerable population is imperative.

811-4 Use of resynchronization therapy in pediatric patients with congenital heart disease and complete heart block

Background: Biventricular pacing has been shown to be a beneficial therapy in adult patients with ventricular dysfunction and intraventricular conduction delay. However, no pediatric applications for this therapy have been tested. We hypothesized that pediatric congenital heart disease patients with complete heart block and poor ventricular function would benefit from conversion to biventricular pacing from traditional single site atrioventricular (DDD) pacing. Patients: A total of 6 patients with congenital heart disease, poor ventricular function and complete heart block were included in this study. Median age at the time of conversion to biventricular pacing was 11.1 months, ranging from 5.6 to 118 months. Diagnoses included complete atrioventricular canal (1), aortic stenosis/subaortic stenosis (4), antiRo, anti-La cardiomyopathy (1). Patients were all treated for heart failure prior to conversion to biventricular pacing, with digoxin (6/6), ACE-inhibitor (6/6), and carvedilol (2/6). Baseline ejection fraction with DDD pacing was 34 ± 12%. Median duration of followup after conversion to biventricular pacing was 2.6 months, ranging from 4 days to 5.8 months. Results: After conversion to biventricular pacing the ejection fraction increased to 57 ± 12%, p<0.004. In all subjects, the ejection fraction improved, with a minimum improvment of 12 EF units. Five patients also showed an improvement in weight for age, p=0.04. Other clinical improvement was noted, with 1 patient removed from the transplant list, and 1 patient tolerating reduction in medical support. Conclusions: Biventricular pacing appears to offer short-term benefit for selected pediatric patients with complete heart block and poor left ventricular function. Further studies looking at the long-term benefit of this therapy in the pediatric population are needed.

ECG SCREENING OF YOUNG ADULTS: A LOW COST MODEL

Background: Sudden cardiac death (SCD) in young adults is a staggering event for a community. It is estimated that over 2,000 of these deaths occur annually in the USA. Experience in Italy utilizing ECG screening has demonstrated an 89% reduction in SCD in young athletes. Recent AHA guidelines acknowledge the benefit of ECG screening but conclude that large scale screening is impractical due to economical and operational considerations. Methods: Since its inception in 2006 the Young Hearts for Life (YH4L) ECG screening program has performed over 48,000 screening ECGs on high school students. Our model utilizes a solitary employee and community volunteers who are trained via a standardized 90 min ECG training session. In this study we analyzed the costs to deliver the program over a 12 month period in 2009. Results: In 2009, 19,279 high school students were tested at 19 area high schools in the suburban Chicago region. Total expenses during this period were