Prolonged and decremental antegrade conduction properties in right anterior accessory connections: Wide QRS antidromic tachycardia of left bundle branch block pattern without Wolff-Parkinson-White configuration in sinus rhythm

Four patients are described who had long conduction times and decremental conduction through right anterior accessory connections. None had Wolff-Parkinson-White syndrome on their ECG. Each had recurrent sustained wide QRS tachycardia due to antegrade conduction through the accessory connection. Three patients underwent epicardial mapping and successful surgical division of their accessory connection. Two of the three had a second accessory connection that was also divided surgically. Each of the three are free of tachycardia without medication. It is postulated that these accessory connections represent the remnants of anterior atrioventricular ring tissue described by Anderson.

Successful surgical treatment of atrial, junctional, and ventricular tachycardia unassociated with accessory connections in infants and children

Five children with severe, life-threatening tachydysrhythmias were treated successfully with surgery. Three had atrial ectopic automatic tachycardia (AET), one had AV junctional (his bundle) automatic ectopic tachycardia (JET), and one had ventricular reentry tachycardia (VT). The mechanism and site of the tachycardia were diagnosed preoperatively using intracardiac electrophysiologic studies (EPS). Medical management with all available drugs failed to control the tachycardia in each patient. The two patients with left atrial AET underwent cryoablation of the focus using cardiopulmonary bypass. The patient with right atrial AET had removal of the anterior one third of the right atrial appendage and cryoablation of the edges. The patient with AV JET first had incision and suture ligation of the bundle of His and implantation of a ventricular pacemaker, but the tachycardia recurred 2 weeks later. Cryoablation of the bundle of His prevented further recurrences. Tachycardia stopped in the patient with VT during incision of a tumor in the apex of the left ventricle. No patient had tachycardia after surgery and none has required medical treatment.

Congenital complete atrioventricular block: clinical and electrophysiologic predictors of need for pacemaker insertion

Because of initial Adams-Stokes attack in the patient with congenital complete atrioventricular (A-V) block may sometimes prove fatal, there is a need to be able to identify the patient at great risk of having such attacks. Twenty-four children with congenital complete A-V block were followed up for 1 to 19 years to determine the efficacy of current methods of predicting risk for Adams-Stokes syncope and the usefulness of pacemaker therapy in relieving symptoms. The heart rate at rest, configuration of surface electrocardiographic complexes, data obtained during intracardiac electrophysiologic study and response to graded treadmill exercise testing were compared in children with and without syncope. One or more Adams-Stokes episodes were experienced by eight children, one of whom died. Only a persistent heart rate at rest of 50 beats/min or less demonstrated any significant (probability [p] less than 0.01) correlation with the incidence of syncope. Intracardiac electrophysiologic study was of little benefit because of site of block did not correlate with syncope. Although the increase in heart rate during treadmill exercise testing showed no correlation with prevalence of syncope or location of block, exercise-induced ventricular ectopic beats may have predictive value in older children and young adults. Ventricular pacemakers were implanted in 10 children. Each child was asymptomatic over a 1 to 10 year follow-up period. Because extreme bradycardia may contribute to the prevalence of Adams- Stokes attacks in children with congenital complete A-V block, careful evaluation of heart rate at rest may be an effective means of differentiating patients at risk of syncope. Pacemaker therapy is a feasible and effective method of treatment in young children and relieves symptoms

Arrhythmogenic right ventricular dysplasia: a cause of ventricular tachycardia in children with apparently normal hearts

Arrhythmogenic right ventricular dysplasia (ARVD), a cardiomyopathy with hypokinetic ares limited to the wall of the right ventricle (RV), has been recently described as a cause of recurrent ventricular tachycardia (VT) in young adults with an otherwise normal heart. We reviewed 26 cases of recurrent VT in children and found 10 patients with no clinically recognizable abnormality aside from the dysrhythmia. Three of these 10 patients had ARVD. These three patients were initially seen at 1, 12, and 14 years of age with premature ventricular contractions (PVCs) and/or VT. Sustained VT occurred spontaneously or during stress testing. The PVCs and the VT were of left bundle branch block contour, suggesting RV site of origin. The diagnosis of ARVD was based on wall motion abnormalities of the RV demonstrated angiographically. We suggest that ARVD could be a significantly common cause of VT in children with an apparently normal heart.

Electrophysiologic studies of supraventricular tachycardia in children. I. Clinical-electrophysiologic correlations

We investigated the clinical features, surface ECG findings, associated with congenital heart disease (CHD), and status at follow-up in 103 children who underwent intracardiac electrophysiologic evaluation of supraventricular tachycardia (SVT). Age at catheterization ranged from 2 days to 17 years (mean 4.2 years). Diagnosis of the mechanism was based upon standard electrophysiologic techniques. Of the 103 patients, 37 had reentry without a bypass tract (10 sinoatrial node, two atrial muscle, and 25 atrioventricular node); 51 had reentry with a bypass tract (28 manifest Wolff-Parkinson-White [WPW], 18 unidirectional retrograde accessory pathway [URAP], an five Lown-Ganong-Levine); and 15 had an ectopic focus (11 atrial, four junctional). Distinguishing features among the common types are depicted in Table III. We conclude that in children the various mechanisms of SVT (1) are likely to be found in different clinical situations, (2) have a different potential for surgical cure, and (3) have a different prognosis for long-term treatment. Since curative surgery was theoretically possible in 57% of our patients (WPW, concealed WPW, atrial, and junctional ectopic), we recommend electrophysiologic study in any patient who has had frequent recurrences of SVT for longer than 1 year and who requires drugs in addition to digoxin for treatment.

Supraventricular tachycardia in children: clinical features, response to treatment, and long-term follow-up in 217 patients

We reviewed the records of 217 children whose first episode of supraventricular tachycardia occurred before 18 years (median age 24 months). There were 112 males and 105 females. Of the 49 with congenital heart disease, SVT began before any operation in 26 and greater than 2 weeks postoperatively in 23. Wolf-Parkinson-White syndrome was present on surface ECG in 47/217 (22%). Congestive heart failure accompanied the first episode of SVT in 38% of the patients who were 4 months of age or younger, and in only 19% of those over 4 months (P less than 0.001). Treatment was successful in stopping SVT within 48 hours in 90/142 (63%). Successful short-term treatment included digoxin 57/184 (68%), cardioversion 12/20 (60%), vagal maneuvers 12/19 (63%), phenylephrine 3/9, and overdrive pacing 4/5. SVT recurred at least once in 83% of all patients. On follow-up (mean 4.6 years), episodes of SVT were still present in 56%. Three patients died--two from incessant SVT and one from a CVA after VSD repair. We conclude that long-term status was difficult to predict, but SVT was present in fewer patients whose age at onset was less than 4 months and in those with unoperated CHD. Early recurrence was not a poor prognostic sign. We recommended treatment for at least one year in all patients with SVT, whether or not the first episode terminates spontaneously.

Postoperative pericardial effusion and its relation to postpericardiotomy syndrome

Postpericardiotomy syndrome often delays recovery from cardiac operation. Pericardial effusion is an important sequela of postpericardiotomy syndrome. To define the relationship between postpericardiotomy syndrome and pericardial effusion, we performed four to seven serial echocardiograms (echoes) between postoperative day 0 and postoperative day 10 in 40 children who had operation requiring pericardiotomy. We also performed daily physical examination on each patient for clinical evidence of postpericardiotomy syndrome. Echocardiographic signs of pericardial effusion developed in 21/40 patients (53%). The effusion was present by postoperative day 5 in 19/21 patients. Clinical signs of postpericardiotomy syndrome occurred in 18/40 patients (45%). Among the 18 patients with postpericardiotomy syndrome, 16 had echocardiographic evidence of pericardial effusion. Thus the sensitivity of the echocardiogram was 89%. The pericardial effusion always developed prior to and persisted through clinical symptoms. We conclude that (1) pericardial effusion is present in over 50% of the patients following cardiac surgery, (2) it develops early in the postoperative period, and (3) once present, the effusion is persistent and frequently followed by clinical evidence of postpericardiotomy syndrome.

Surgical treatment of supraventricular tachycardia in infants and children

The technique, indications and results of surgical division of accessory atrioventricular connections in 10 infants and children with drug-resistant supraventricular tachycardia are described. The patients ranged in age from 6 months to 15 years. Four patients had associated congenital heart disease. Division of accessory connections were performed on free wall pathways in nine patients (seven right atrial, two left atrial) and on a septal pathway in one patient. Four patients had both anterograde and retrograde conduction over the accessory connection (manifest Wolff-Parkinson-White conduction) whereas six had only retrograde conduction (concealed Wolff-Parkinson-White conduction). The manifst Wolff-Parkinson-White conduction was abolished by surgical division in all four patients. In 8 of the 10 patients the procedure stopped the attacks of paroxysmal supraventricular tachycardia for follow-up periods ranging from 9 months to 3 1/2 years; no patient receives medication to date.

Effect of chemical sympathectomy on myocardial cell division in the newborn rat

Myocardial chemical sympathectomy was achieved by daily SC injection of 100 micrograms/g body weight of 6-OH-dopamine to each of 239 Holtzman newborn rat pups for the first seven days of life. Effective sympathectomy was verified by identifying a decrease in ventricular myocardial norepinephrine concentrations to 31% +/- 12 S.E. of control at 20 days of age. Activity of DNA polymerase was used to indicate the extent of myocardial cell division. Beginning at eight days of age, DNA polymerase activity was increased in the sympathectomized pups relative to control. The DNA polymerase activity was highest relative to control at 16 days (235% +/- 31 S.E.) and remained elevated beyond 20 days (188% +/- 30 of control). The DNA polymerase data was analyzed by covariance and was significantly greater in the 6-OH-dopamine rat pups (P < 0.001).

Automated on-line measurement of electrophysiologic intervals during cardiac catheterization

A small dedicated, computer-controlled waveform analyzer was used to automatically measure the R-R cycle length, low right atrium to His, and His to ventricle intervals obtained during electrophysiologic studies on 35 patients. These measurements were compared to intervals hand-measured separately and found to correlate well (0.92, 0.83, and 0.75, respectively). The sources of error, possible pitfalls, and future uses of this technique are discussed.

Mechanisms of cardiac arrhythmias after the Mustard operation for transposition of the great arteries

To determine the mechanisms of the cardiac arrhythmias frequently seen after the Mustard operation for transposition of the great arteries, intracardiac electrophysiologic studies were performed in 52 children 1 to 8 years after the Mustard operation. Sinus nodal automaticity as judged from the response to rapid atrial pacing was abnormal in 28 of the 52 children. Sinoatrial conduction (conduction of the sinus impulse to the atrium) was found to be abnormal in three of nine patients studied with the atrial extrastimulus method. Conduction of the sinus impulse from the high right atrium to the atrioventricular (A-V) node was abnormally delayed in only 2 of 41 subjects. The low lateral wall of the right atrium was depolarized late in 3 of 11 subjects (including the preceding 2). Two subjects showed delayed A-V nodal conduction and one delayed His-Purkinje conduction. The mechanism of supraventricular tachycardia induced in the laboratory was determined to be sinoatrial nodal reentry in four subjects and atrial muscle reentry in four. Two of the four with atrial muscle reentry had prolonged high right atrium to low lateral right atrium intervals during sinus rhythm. Thus, damage to the sinus node remains the most common cause of arrhythmias after the Mustard operation. In addition, delayed atrial conduction may predispose to atrial muscle reentrant tachycardia.

Electrophysiologic effect of digitalis on sinoatrial nodal function in children

Despite the prevalence of digitalis usage in children, the electrophysiologic effects of digitalis on sinoatrial (S-A) nodal function is unknown in this age group. The purpose of this study was to determine the effect of digitalis on sinoatrial conduction time as well as on S-A nodal automatically. Ten subjects (mean age 10.5 years) underwent electrophysiologic assessment of S-A nodal function before and 30 minutes after administration of ouabain (0.01 mg/kg). Total S-A conduction time increased in each subject and the mean value after ouabain (182 msec +/- 13 standard errors of the mean [SEM]) was significantly higher (P less than 0.01) than before (149 msec +/- 11). The sinus cycle length was variable after ouabain (P greater than 0.1). The corrected sinus nodal recovery time also was variable (P greater than 0.1), decreasing substantially in three subjects. Mechanisms of the effect of digitalis on the S-A node and atrium are proposed and discussed. It is concluded that digitalis prolongs the S-A conduction time in children with normal S-A nodal function. By prolonging the S-A conduction time, digitalis may artifactually shorten corrected S-A nodal recovery time in some patients.

Wolff-Parkinson-White syndrome in children: electrophysiologic and pharmacologic characteristics

Intracardiac electrophysiologic studies were performed on 28 infants and children, ages 1 month to 18 years, with the Wolff-Parkinson-White syndrome to try to determine 1) the electrophysiologic characteristics of the accessory connection and 2) the mechanisms of associated supraventricular dysrhythmias. Although the antegrade refractory periods of the normal conduction system were shorter than those found in adults, those of the accessory connection were slightly longer. Reciprocating supraventricular tachycardia (SVT), which had been a clinical problem in 26 of 28, could be induced in the laboratory in all 26 subjects. The mechanism involved reentry with antegrade conduction through the atrioventricular (AV) node and retrograde through the accessory connection in 22. Eleven of these 22 had a wide QRS during tachycardia due to a bundle branch block. Three other subjects had wide QRS tachycardia, but the mechanism involved antegrade conduction through the accessory connection and retrograde through the AV node. The other patient had AV node reentry tachycardia. Two patients did not have clinical SVT, and in these two, SVT could not be induced. Neither patient had retrograde conduction through the accessory connection. The site of the accessory connection could be identified in 26 subjects by the sequence of retrograde activation of the atrium during SVT or ventricular pacing. Digitalis shortened the refractory period of the accessory connection in five of the eight patients studied.

Prognosis for the newborn with transposition of the great arteries

To determine the prognosis for the newborn with transposition of the great arteries, the clinical course of 112 consecutive neonates with dextrotransposition was reviewed. Patients were managed with balloon atrial septostomy at initial cardiac catheterization, palliative operation if needed in the 1st year of life and Mustard's intraatrial baffle repair. The 1st month of life was the period of greatest risk (8 percent mortality rate). Between balloon septostomy and baffle repair, 14 of 103 patients at risk (14 percent) either died or had a cerebrovascular accident. The mortality rate at baffle repair was 14 percent (10 deaths in 71 patients), and there were 3 late postoperative deaths. Actuarial analysis of the data indicates that with this plan of management, approximately 50 percent of newborns with transposition of the great arteries will survive 5 years with excellent function and an additional 15 to 20 percent will survive with one or more medical handicaps.

Thoracoabdominal ectopia cordis with mosaic Turner's syndrome: Report of a case

A child was treated for thoracoabdominal ectopia cordis and an associated chromosomal defect. Contrary to most cases in which death is due to the externally situated heart and abdominal viscera, this patient died from congenital heart disease.