Comparison of Intraoperative Aminophylline Versus Furosemide in Treatment of Oliguria During Pediatric Cardiac Surgery.

OBJECTIVES: To determine if intraoperative aminophylline was superior to furosemide to prevent or attenuate postoperative cardiac surgery-associated acute kidney injury. DESIGN: Single-center, historical control, retrospective cohort study. SETTING: PICU, university-affiliated children's hospital. PATIENTS: Children with congenital heart disease in PICU who received furosemide or aminophylline to treat intraoperative oliguria. INTERVENTIONS: Intraoperative oliguria was treated either with furosemide (September 2007 to February 2012) or with aminophylline (February 2012 to June 2013). The postoperative 48 hours renal outcomes of the aminophylline group were compared with the furosemide group. The primary outcomes were acute kidney injury and renal replacement therapy use at 48 hours postoperatively. Surgical complexity was accounted for by the use of Risk Adjustment for Congenital Heart Surgery-1 score. MEASUREMENTS AND MAIN RESULTS: The study involves 69 months of observation. There were 200 cases younger than 21 years old reviewed for this study. Eighty-five cases (42.5%) developed acute kidney injury. The aminophylline group patients produced significantly more urine (mL/kg/hr) during the first 8 hours postoperatively than furosemide patients (5.1 vs 3.4 mL/kg/hr; p = 0.01). The urine output at 48 hours postoperatively was similar between the two groups. There was no difference in acute kidney injury incidence at 48 hours between the aminophylline and furosemide groups (38% vs 47%, respectively; p = 0.29). Fewer aminophylline group subjects required renal replacement therapy compared to the furosemide group subjects (n = 1 vs 7, respectively; p = 0.03). In the multi-variant predictive model, intraoperative aminophylline infusion was noted as a negative predictive factor for renal replacement therapy, but not for cardiac surgery-associated acute kidney injury. CONCLUSION: The intraoperative use of aminophylline was more effective than furosemide in reversal of oliguria in the early postoperative period. There were less renal replacement therapy-requiring acute kidney injury in children in the aminophylline group. Future prospective studies of intraoperative aminophylline to prevent cardiac surgery-associated acute kidney injury may be warranted.

Ventricular tachycardia in infants with structurally normal heart: a benign disorder.

We evaluated the presentation, treatment, and outcome of infants who present with ventricular tachycardia in the first year of life. Seventy-six infants were admitted to our institution with a diagnosis of ventricular tachycardia between January, 1987 and May, 2006. Forty-five infants were excluded from the study because of additional confounding diagnoses including accelerated idioventricular rhythm, Wolff-Parkinson-White syndrome, supraventricular tachycardia with aberrancy, long QT syndrome, cardiac rhabdomyoma, myocarditis, congenital lesions, or incomplete data. The remaining 31 included infants who had a median age at presentation of 1 day, with a range from 1 to 255 days, and a mean ventricular tachycardia rate of 213 beats per minute, with a range from 171 to 280, at presentation. The infants were treated chronically with propranolol (38.7%), amiodarone (12.9%), mexiletine (3.2%), propranolol and mexiletine (9.7%), or propranolol and procainamide (6.5%). The median duration of treatment was 13 months, with a range from 3 to 105 months. Ventricular tachycardia resolved spontaneously in all infants. No patient died, or received catheter ablation or device therapy. Median age at last ventricular tachycardia was 59 days, with a range from 1 to 836 days. Mean follow-up was 45 months, with a range from 5 to 164 months, with a mean ventricular tachycardia-free period of 40 months. Infants with asymptomatic ventricular tachycardia, a structurally normal heart, and no additional electrophysiological diagnosis all had spontaneous resolution of tachycardia. Furthermore, log-rank analysis of the time to ventricular tachycardia resolution showed no difference between children who received chronic outpatient anti-arrhythmic treatment and those who had no such therapy. While indications for therapy cannot be determined from this study, lack of symptoms or myocardial dysfunction suggests that therapy may not be necessary.

Outcome of high-risk neonates with congenital complete heart block paced in the first 24 hours after birth.

OBJECTIVE: Risk factors for poor outcome with congenital complete heart block include prematurity, low birth weight, hydrops, low ventricular rates, and congenital heart disease. In this group, medical therapy is often ineffective, pacing is technically challenging, and mortality exceeds 80%. The purpose of this study is to assess outcomes of patients with congenital complete heart block who were paced in the first 24 hours after birth owing to the presence of known risk factors. METHODS: We performed a retrospective review of patients with congenital complete heart block paced in the first 24 hours after birth at our institution between November 1, 1995, and July 31, 2007. RESULTS: Thirteen patients were identified, 4 of whom had heterotaxy syndrome. Eleven patients had temporary epicardial pacing wires placed; 2 received permanent pacemakers as the initial mode of pacing. There were 7 deaths (54% mortality) at a mean age of 19.9 +/- 19 days. Among 7 patients with structural heart disease, there was 1 survivor. Among 6 patients with structurally normal hearts, there were 5 survivors (P = .025). Patients with temporary wires who survived to permanent pacemaker implantation (6/11) used their temporary leads for 33.8 +/- 18.3 days. CONCLUSIONS: In the severely affected fetus with congenital complete heart block and significant structural heart disease, outcomes remain poor; however, neonates with congenital complete heart block and structurally normal hearts who are monitored antenatally and delivered in a planned fashion at an institution capable of early pacing can have favorable outcomes. The use of temporary pacing wires is an option in the management of these patients.

Substrate characterization of ventricular tachycardia in a porcine model of tetralogy of Fallot using noncontact mapping.

BACKGROUND: Ventricular tachycardia (VT) in patients following tetralogy of Fallot (TOF) repair is challenging to map because of the presence of scar, patch material, and hemodynamic residua of surgery. This study investigates whether noncontact mapping can identify the arrhythmia substrate in a porcine model that involves a right ventricular outflow tract (RVOT) patch and either chronic volume or pressure load on the right ventricle. METHODS: Nine infant pigs (3-5 kg) underwent surgery involving an RVOT patch and creation of pulmonary insufficiency (PI, n = 4) or pulmonary stenosis (PS, n = 5). After a mean of 4.2 months, pigs underwent invasive electrophysiology studies (EPS) with noncontact mapping (Ensite, St. Jude Medical, St. Paul, MN USA) of the right ventricle. Automated, unipolar voltage maps (VM) were constructed during sinus rhythm. Threshold for substrate was set at -0.5 mV and incrementally adjusted to higher values until a contiguous region of low voltage was delineated. Programmed stimulation was performed to induce VT. VT activation was correlated to location of VM defined substrate. Three control pigs underwent EPS and VM. RESULTS: Free-wall RVOT substrate was identified in each of the model animals, correlating to location of the patch. The mean voltage threshold was -1.1 mV. VT was induced in 6/9 animals. Diastolic activation approximated the inferior or lateral border of the substrate in all animals. No RVOT substrate was identified in the control pigs. CONCLUSION: Automated voltage mapping of sinus beats identifies substrate for VT in a porcine model of TOF. Consistent diastolic activation of the substrate border was found during VT. Targeting this area may be useful in the ablation of VT after repair of TOF.

Heart rate variability following neonatal heart surgery for complex congenital heart disease.

BACKGROUND: Altered cardiac autonomic control may play a role in the morbidity and mortality suffered by neonates who undergo surgery for complex congenital heart disease (CHD). The purpose of this study was to evaluate cardiac autonomic activity, as measured by spectral indices of heart rate variability (HRV), prior to and early after infant surgery for CHD and attempt to correlate HRV indices with clinical outcome. In addition, we assessed the hypothesis that single-ventricle physiology and surgical interruption of the great arteries negatively affects HRV. METHODS: Sixty neonates prospectively wore 24-hour Holter monitors at three time points: before and early after CHD surgery, and at 3- to 6-month follow-up. Standard spectral indices of HRV were measured. RESULTS: In the early postoperative time point, patients with single-ventricle physiology had lower low-frequency power (LF) compared to patients with two ventricles (P=0.040). Surgical interruption of the great arteries did not affect HRV in this cohort. For the entire cohort, LF (P=0.004) and high-frequency power (HF) (P<0.001) increased over the three time points, while LF/HF (P=0.119) did not significantly change. In the multivariable linear regression model, significant predictors of longer postoperative hospital stay included longer total support time (P=or<0.001), longer duration of inotrope support (P=0.012), elevated mean heart rate at postoperative time point (P=0.002), and lower LF/HF ratio at the postoperative time point (P=0.014). CONCLUSION: Patients with single-ventricle physiology have a significant physiologic reduction in LF in the early postoperative period compared to patients with two ventricles. Diminished cardiac autonomic control is associated with longer hospitalization following neonatal cardiac surgery.

Usefulness of magnetic resonance imaging for the diagnosis of right ventricular dysplasia in children.

Cardiac magnetic resonance (CMR) has been helpful in adults in the diagnosis of arrhythmogenic right ventricular dysplasia. Short of direct surgical observation or autopsy, no gold standard exists. CMR diagnostic criteria include right atrial and ventricular dilation, regional right ventricular (RV) wall motion abnormalities, outflow tract ectasia, and myocardial fatty infiltration. To determine whether adult diagnostic criteria are useful in children referred for CMR for this diagnosis, the images and records of 81 patients (aged 11.5 +/- 5.5 years) over an 8-year period were reviewed. Histories included ventricular tachycardia, palpitations, dilated right ventricle, syncope, near sudden death, or family history of RV dysplasia. Four families were studied with parents who had RV dysplasia diagnosed by surgery, explanted heart, or CMR. CMR imaging included T1-weighted imaging, cine, 1-dimensional RV myocardial tagging, and phase-encoded velocity mapping, and 2 patients underwent delayed-enhancement CMR. Only 1 of the 81 patients met 5 of the criteria. None of the others met >2 of the criteria, and only 2 patients met 1 or 2 criteria. For questionable regional wall motion abnormalities, RV myocardial tagging was helpful. In conclusion, CMR of patients with a history suspicious for the diagnosis of RV dysplasia is a low-yield test in children. This may be due to the evolving nature of the disease, which does not manifest itself from a morphologic or ventricular-function standpoint until later in development. Follow-up studies as patients age may be advantageous.

Induction of atrial fibrillation after the routine use of adenosine.

We report a case of atrial fibrillation induction after the use of adenosine for the termination of supraventricular tachycardia in the emergency department. Atrial fibrillation is not an uncommon side effect of adenosine administration. Hemodynamic collapse may occur if an antegrade-conducting accessory pathway allows for a rapid ventricular response. Therefore, we would recommend that the use of adenosine be limited to situations in which there is appropriate electrocardiographic monitoring and emergency resuscitative capabilities.

The roles of chronic pressure and volume overload states in induction of arrhythmias: an animal model of physiologic sequelae after repair of tetralogy of Fallot.

OBJECTIVE: Sudden death occurs in as many as 8% of patients after repair of tetralogy of Fallot and has been attributed to arrhythmias. The purpose of this study was to establish an animal model to evaluate the individual contribution of different physiologic sequelae after tetralogy of Fallot repair in the development of late-onset arrhythmias. METHODS: Forty-nine piglets were divided into 5 groups: (1) pulmonary artery band; (2) pulmonary valvotomy; (3) pulmonary artery band plus pulmonary valvotomy; (4) infundibular scar; and (5) age-matched control animals. Baseline and follow-up electrocardiograms were obtained and recorded, as well as changes in QRS duration. A total of 45 animals underwent hemodynamic evaluation and programmed electrical stimulation at 5.6 months postoperatively. RESULTS: Sustained ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation) were induced in 31.1%, and atrial arrhythmias were induced in 33.3%. The pulmonary valvotomy group was 30 times more likely to evidence arrhythmias than control animals for sustained ventricular tachycardia/ventricular fibrillation, as well as atrial arrhythmias (P = .01). The pulmonary artery band group was 15 times more likely to evidence atrial arrhythmias than control animals (P = .02). Prolonged QRS duration was predictive of inducibility of both atrial arrhythmias (P < .01) and sustained ventricular tachycardia/ventricular fibrillation (P = .01). Mean right atrial (P = .01) and capillary wedge (P = .01) pressures predicted atrial arrhythmia inducibility. Right ventricular end-diastolic pressure predicted atrial arrhythmia (P= .01) and sustained ventricular tachycardia/ventricular fibrillation inducibility (P = .05). Right ventricular systolic pressure did not predict inducibility of either atrial arrhythmias (P = .10) or sustained ventricular tachycardia/ventricular fibrillation (P = .94). CONCLUSIONS: Chronic right ventricular volume overload resulted in an increased incidence of inducible ventricular and atrial arrhythmias.

Postpericardiotomy syndrome after permanent pacemaker implantation in children and young adults.

BACKGROUND: Postpericardiotomy syndrome (PPS) occurs in 10% to 50% of pediatric patients after cardiac surgery. The incidence and outcome of PPS after permanent pacemaker implantation in children is not described. METHODS: A retrospective analysis was performed of all pediatric patients who underwent isolated placement of a pacemaker between January 1984 and December 2002. Patients who underwent congenital heart surgery at the time of pacemaker implantation were excluded. PPS was diagnosed on the basis of clinical symptoms with echocardiographic confirmation of a pericardial effusion. RESULTS: Four hundred and forty-three pacemakers (237 epicardial, 206 transvenous) were implanted in 370 patients (median age 10 years, range 2 months to 24 years). Eight (2%) episodes of PPS (6 epicardial, 2 transvenous) occurred in 7 patients. The median time from implantation to PPS was 12.5 days (range 8 to 22 days). Six (75%) episodes followed primary pacemaker implantation, two occurred after subsequent lead revision. Three patients were initially treated with medical therapy (1 nonsteroidal agents, 2 steroids), and 1 required subsequent pericardiocentesis. Five patients underwent initial pericardiocentesis followed by medication. One patient had echocardiographic recurrence of a pericardial effusion 3 weeks after a nonsteroidal taper, with resolution after nonsteroidal agents were reinitiated. One patient required a pericardial window for a persistent effusion. No pacemaker was explanted. CONCLUSIONS: PPS occurred in 2% of children undergoing isolated pacemaker implantation of both epicardial and transvenous systems. PPS is usually managed successfully with medical therapy. Patients with medical treatment failure were successfully treated with pericardiocentesis or the surgical creation of a pericardial window.

Efficacy of prophylactic epicardial pacing leads in children and young adults.

BACKGROUND: Epicardial pacemakers are often required in children and young adults who cannot undergo a transvenous system because of patient size, vascular barriers, or significant residual intracardiac shunts. Prophylactic epicardial pacing leads, placed at the time of concomitant congenital heart surgery, may reduce a late thoracotomy or sternotomy. The efficacy of prophylactic epicardial leads in the pediatric population is unknown. METHODS: A retrospective review of the cardiovascular surgery and pacemaker databases at The Children's Hospital of Philadelphia identified all patients less than or equal to 21 years of age, who underwent placement of an epicardial pacing lead between January 1, 1990 and December 31, 2002. Prophylactic epicardial pacing leads placed at the time of a concomitant congenital heart procedure were compared to standard epicardial leads that were connected to a simultaneous programable generator. Pacing and sensing threshold data were obtained in prophylactic epicardial leads at the time of lead retrieval and 6 month follow-up and compared to standard epicardial pacing leads. RESULTS: Twenty-two (13 ventricular, 9 atrial) prophylactic epicardial pacing leads were retrieved in 13 patients at a median of 252 days (7 days to 3.98 years) from the time of initial implant and compared to 256 (164 ventricular, 92 atrial) standard epicardial leads placed in 142 patients. Nineteen (86%) prophylactic epicardial leads had acceptable pacing and sensing thresholds at lead retrieval. Only 1 patient with atrial and ventricular leads had poor pacing and sensing at retrieval and required a redo-sternotomy for placement of new atrial and ventricular epicardial pacing leads. For the remaining atrial (n = 7) and ventricular (n = 12) prophylactic epicardial leads, there was no significant difference in pacing (atrial, 1.59 +/- 1.1 microJ; ventricular, 1.98 +/- 1.9 microJ) or sensing (atrial, 3.6 +/- 1.8 mV; ventricular, 13.8 +/- 4.4 mV) compared to standard pacing (atrial, 2.1 +/- 1.8 microJ; ventricular, 1.9 +/- 3.4 microJ) and sensing (atrial, 3.3 +/- 1.7 mV; ventricular, 11.3 +/- 5.3 mV) epicardial leads. Six-month follow-up pacing and sensing thresholds were not significantly different between the prophylactic and standard epicardial pacing leads. CONCLUSIONS: Prophylactic epicardial pacing leads can be successfully placed and retrieved in a subset of children and young adults who will likely require pacing at a later date. Prophylactic leads have comparable pacing and sensing qualities at lead retrieval and short-term follow-up compared to standard epicardial leads. Consideration for prophylactic epicardial pacing leads will likely reduce the need for a late thoracotomy or sternotomy.

Postoperative junctional ectopic tachycardia in children: incidence, risk factors, and treatment.

BACKGROUND: Junctional ectopic tachycardia (JET) occurs commonly after pediatric cardiac operation. The cause of JET is thought to be the result of an injury to the conduction system during the procedure and may be perpetuated by hemodynamic disturbances or postoperative electrolyte disturbances, namely hypomagnesemia. The purpose of this study was to determine perioperative risk factors for the development of JET. METHODS: Telemetry for each patient admitted to the cardiac intensive care unit from December 1997 through November 1998 for postoperative cardiac surgical care was examined daily for postoperative JET. A nested case-cohort analysis of 33 patients who experienced JET from 594 consecutively monitored patients who underwent cardiac operation was performed. Univariate and multivariate analyses were conducted to determine factors associated with the occurrence of JET. RESULTS: The age range of patients with JET was 1 day to 10.5 years (median, 1.8 months). Univariate analysis revealed that dopamine or milrinone use postoperatively, longer cardiopulmonary bypass times, and younger age were associated with JET. Multivariate modeling elicited that dopamine use postoperatively (odds ratio, 6.2; p = 0.01) and age less than 6 months (odds ratio, 4.0; p = 0.02) were associated with JET. Only 13 (39%) of the patients with JET received therapeutic interventions. CONCLUSIONS: Junctional ectopic tachycardia occurred in 33 (5.6%) of 594 patients who underwent cardiac operation during the study period. Postoperative dopamine use and younger age were associated with JET. It may be speculated that dopamine should be discontinued in the presence of postoperative JET.

Synthesis and characterization of a new family of square-planar nickel(II) carbonyl derivatives.

The reaction of [NBu(4)](2)[Ni(C(6)F(5))(4)] (1) with solutions of dry HCl(g) in Et(2)O results in the protonolysis of two Nibond;C(6)F(5) bonds giving [NBu(4)](2)[[Ni(C(6)F(5))(2)](2)(mu-Cl)(2)] (2 a) together with the stoichiometrically required amount of C(6)F(5)H. Compound 2 a reacts with AgClO(4) in THF to give cis-[Ni(C(6)F(5))(2)(thf)(2)] (3). Reacting 3 with phosphonium halides, [PPh(3)Me]X, gives dinuclear compounds [PPh(3)Me](2)[[Ni(C(6)F(5))(2)](2)(mu-X)(2)] (X=Br (2 b) or I (2 c)). Solutions of compounds 2 in CH(2)Cl(2) at 0 degrees C do not react with excess CNtBu, but do react with CO (1 atm) to split the bridges and form a series of terminal Ni(II) carbonyl derivatives with general formula Qcis-[Ni(C(6)F(5))(2)X(CO)] (4). The nu(CO) stretching frequencies of 4 in CH(2)Cl(2) solution decrease in the order Cl (2090 cm(-1))>Br (2084 cm(-1))>I (2073 cm(-1)). Compounds 4 revert to the parent dinuclear species 2 on increasing the temperature or under reduced CO pressure. [NBu(4)]cis-[Ni(C(6)F(5))(2)Cl(CO)] (4 a) reacts with AgC(6)F(5) to give [NBu(4)][Ni(C(6)F(5))(3)(CO)] (5, nu(CO)(CH(2)Cl(2))=2070 cm(-1)). Compound 5 is also quantitatively formed ((19)F NMR spectroscopy) by 1:1 reaction of 1 with HCl(Et(2)O) in CO atmosphere. Complex 3 reacts with CO at -78 degrees C to give cis-[Ni(C(6)F(5))(2)(CO)(2)] (6, nu(CO)(CH(2)Cl(2))=2156, 2130 cm(-1)), which easily decomposes by reductive elimination of C(6)F(5)bond;C(6)F(5). Compounds 3 and 6 both react with CNtBu to give trans-[Ni(C(6)F(5))(2)(CNtBu)(2)] (7). The solid-state structures of compounds 3, 4 b, 6, and 7 have been established by X-ray diffraction methods. Complexes 4-6 are rare examples of square-planar Ni(II) carbonyl derivatives.

Pediatric pacemaker infections: twenty years of experience.

OBJECTIVE: We sought to evaluate possible predictors of early and late pacemaker infections in children. METHODS: A review was performed of all pacemakers implanted in children at The Children's Hospital of Philadelphia between 1982 and 2001. Infections were classified as superficial cellulitus, deep pacemaker pocket infection necessitating removal, or positive blood culture without an identifiable source. RESULTS: A total of 385 pacemakers (224 epicardial and 161 endocardial) were implanted in 267 patients at 8.4 +/- 6.2 years. All 2141 outpatient visits were reviewed (median follow-up, 29.4 months; range, 2-232 months). There were 30 (7.8%) pacemaker infections: 19 (4.9%) superficial infections; 9 (2.3%) pocket infections; and 2 (0.5%) isolated positive blood cultures. All superficial infections resolved with intravenous antibiotics. The median time from implantation to infection was 16 days (range, 2 days-5 years). Only 1 deep infection occurred after primary pacemaker implantation. Six patients with deep infections were pacemaker dependent and were successfully managed with intravenous antibiotics, followed by lead-generator removal and implantation of a new pacemaker in a remote location. In univariate analyses trisomy 21 (relative risk, 3.9; P <.01), pacemaker revisions (relative risk, 2.5; P <.01), and single-chamber devices (relative risk, 2.4; P <.05) were identified as predictors of infection. However, in multivariate analyses only trisomy 21 and pacemaker revisions were predictors. CONCLUSIONS: The incidences of superficial and deep pacemaker infections were 4.9% and 2.3%, respectively. Trisomy 21 and pacemaker revisions were significant risk factors in the development of infection after pacemaker implantation. For primary pacemaker implantation, the risk of infection requiring system removal is low (0.3%).

Sinus node dysfunction and atrial tachycardia after the Fontan procedure: The scope of the problem.

Similar to other atrial baffling procedures, the Fontan procedure exposes patients to ongoing morbidity and mortality. The development of the bradycardia-tachycardia syndrome can have adverse effects on already-marginal hemodynamics and ventricular function. Patients with Fontan physiology and sinus node dysfunction can be managed with antibradycardic pacemakers. Atrial arrhythmias after "completion Fontan" are difficult to treat and usually require either antiarrhythmic agents, antitachycardic pacemakers, or radiofrequency catheter ablation of the re-entrant circuit. Successful treatment of atrial flutter occurs in only 50% to 70% of patients. There is a high recurrence rate of atrial flutter with any of the accepted management strategies. Copyright 1998 by W.B. Saunders Company

Management of postoperative arrhythmias and junctional ectopic tachycardia.

The critical postoperative period in children who have undergone palliative or corrective surgery for congenital heart disease is often complicated with cardiac arrhythmias. In spite of improved myocardial preservation techniques and better understanding of the surgical anatomy of the conduction system, postoperative arrhythmias are inevitable. Although most arrhythmias are transient, they can be associated with high mortality and morbidity if vigorous appropriate management is not instituted. This is especially true for postoperative junctional ectopic tachycardia. Lack of atrioventricular synchrony and reduced diastolic time secondary to a fast heart rate lead to decreased cardiac output, and the patient's condition tends to deteriorate rather rapidly. Recent advances in the management of postoperative arrhythmias have been gratifying. The most encouraging response has been that of junctional ectopic tachycardia to intravenous amiodarone. Also, the practice of routinely placing temporary epicardial wires in all patients undergoing surgery for congenital heart disease has provided a very useful diagnostic and therapeutic tool. Early recognition, precise diagnosis, and timely therapy can be very effective in avoiding adverse hemodynamic consequences of postoperative arrhythmias. Copyright 1998 by W.B. Saunders Company