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Biomedical subjects

P C Gillette

Publications and source records attributed to P C Gillette.

At least 55 records · Page 3Linked to original sources
PubMed1994

Radiofrequency catheter ablation for tachyarrhythmias in children and adolescents. The Pediatric Electrophysiology Society.

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 greater likelihood of sustained success. Conversely, a right free-wall pathway, the presence of other heart disease, and higher body weight were all associated with a lesser chance of sustained success. Recurrences of arrhythmia accounted for 45 percent of the failures overall in the series. Atrial ectopic-focus tachycardia had the highest recurrence rate. The total complication rate was 4.8 percent (35 of 725 procedures), and the only variables that independently correlated with a higher complication rate were very low weight and less institutional experience. CONCLUSIONS: These early results suggest that radio-frequency catheter ablation has a good success rate and a low complication rate in pediatric patients, especially when it is carried out in experienced pediatric cardiology centers.

Adolescent↗
PubMed1994

Neurocardiogenic syncope in children with a normal heart.

OBJECTIVES: The purpose of this study was to review the results of investigation and management of children with syncope and a structurally normal heart. BACKGROUND: Syncope is a common clinical problem and has many etiologies. Autonomic testing and, in particular, the tilt/orthostatic test have helped to positively diagnose neurocardiogenic syncope in a high proportion of such patients. METHODS: Patient case notes and autonomic test charts were reviewed in 162 children aged 1 to 20 years (mean age 12.8 years) with syncope. The autonomic test consisted of orthostatic maneuver, carotid sinus massage, diving reflex, Valsalva maneuver and dose response to intravenous boluses of isoproterenol and phenylephrine. Serum levels of epinephrine and norepinephrine were drawn during the orthostatic test. After confirmation of neurocardiogenic syncope, treatment was begun with fludrocortisone and salt, and beta-adrenergic blocking agents were used as a second line of therapy when indicated. RESULTS: The orthostatic test was positive for neurocardiogenic syncope in 100 patients (62%) and negative in 62 (38%). Patients in the former group were older, were more often female and had a diminished response to carotid sinus massage, a higher Valsalva ratio and a higher supine epinephrine level. Both groups showed an increase in epinephrine and norepinephrine levels at 5 min of standing. In the orthostatic positive group at the time of syncope, norepinephrine levels decreased, whereas epinephrine levels increased. Patients in this group were also more sensitive to the vasodilating effect of isoproterenol but not to its chronotropic effects. Eleven patients had cardioinhibitory syncope (asystole > or = 3 s). Of these, three had pacemaker implantation. Fludrocortisone and salt used in 84 patients in the orthostatic positive group produced resolution of symptoms in 55 patients (65%) and improvement in 14 (17%). Ten patients received beta-blockers, with resolution in four and improvement in four. CONCLUSIONS: Patients with orthostatic test-proved neurocardiogenic syncope show evidence of autonomic dysfunction. They also show beta-adrenergic hypersensitivity. Treatment initiated on the basis of the protocol was associated with amelioration of symptoms in the majority of patients.

Adrenergic beta-Antagonists↗
PubMed1994

The cost of congenital heart disease in children and adults. A model for multicenter assessment of price and practice variation.

OBJECTIVE: To assess the cost of congenital heart disease (CHD) and to assess whether practice pattern or price was more responsible for variation. RESEARCH DESIGN AND SETTING: Data were collected from Charleston, NC; Columbus, Ohio; Detroit, Mich; Houston, Tex; Los Angeles, Calif; and New York, NY. The CHD was first classified as to physiologic characteristics and severity. For each type of CHD, the number of clinic visits, hospitalizations, and years of medication use were estimated. RESULTS: On the basis of actual charges, the "prices" were calculated as follows, in 1992 dollars: for patients from birth to 21 years: benign disease (19% of patients), $3940; acyanotic disease (45%), $49,730; cyanotic disease (36%), $102,084; and average for all CHD categories, $59,877; for patients 22 to 40 years of age (of whom 24% had resolved defects or were dead): benign disease (19%), $3470; acyanotic disease (52%), $12,981; cyanotic disease (29%), $39,187; and average for all CHD, $18,773. The cost for the group from birth to 21 years varied from $47,500 to $73,600, accounting for 55% by practice (number of echocardiograms and cardiac catheterizations) and 45% by price, although mortality was similar. CONCLUSIONS: The treatment of CHD is comparatively inexpensive, especially in adult survivors. The variation in both practice and price bears further study, with comparison to determine the most cost-effective strategies for treating these patients.

Adolescent↗
PubMed1994

Surgical treatment of cardiac dysrhythmias in infants and children.

A variety of cardiac rhythm disturbances that occur in infants and children may be refractory to medical or catheter ablation therapy, or both, and thus require surgical ablation. These dysrhythmias include Wolff-Parkinson-White syndrome, atrial automatic tachycardia, atrioventricular node reentry tachycardia, and ventricular tachycardia. The surgical technique originally used in adults may be equally well applied in infants and small children. In the interval from July 1, 1984, through December 31, 1993, a total of 130 infants and children (< or = 16 years old) underwent surgical treatment for various forms of dysrhythmias (96 with Wolff-Parkinson-White syndrome, 8 with atrioventricular node reentry, 11 with atrial automatic tachycardia, and 15 with ventricular tachycardia). The success rate for completely abolishing these arrhythmias has been 92% for the Wolff-Parkinson-White syndrome, 100% for atrioventricular node reentry, and 64% for atrial automatic tachycardia. In infants younger than 2 years, the success rate for the surgical treatment of ventricular tachycardia is 100%, but the long-term success in older children has been poor. One patient sustained a severe intraoperative neurologic event that resulted in her death (operative mortality, 0.7%). Ventricular function returned to normal in all patients in whom it was abnormal preoperatively. These data suggest that the surgical treatment of these dysrhythmias remains a viable alternative in those patients whose dysrhythmias are refractory to medical therapy, those in whom catheter ablation has been unsuccessful, or those in whom both situations apply.

Arrhythmias, Cardiac↗
PubMed1994

Pacemaker failure due to pocket emphysema.

Pocket emphysema is an unusual cause of failure of a permanent pacemaker. Reported herein is temporary failure of a unipolar DDD pacemaker caused by pocket emphysema in a pediatric patient.

Equipment Failure↗
PubMed1994

Management of atrial flutter after the Fontan procedure.

OBJECTIVES: The purpose of this study was to review the management of atrial flutter occurring after the Fontan procedure. BACKGROUND: Atrial flutter occurs frequently after the Fontan procedure and is often hemodynamically poorly tolerated. METHODS: The patients' charts were reviewed for relevant information. RESULTS: Between 1984 and 1992, 18 patients had atrial flutter after the Fontan procedure. The underlying heart defect was tricuspid atresia in nine, mitral atresia in six and double inlet left ventricle in three. All but three patients had undergone previous palliative surgery. The time interval from Fontan operation to atrial flutter was < 1 day to 16 years (mean 3.7 years). Seven had early atrial flutter before leaving the hospital. Electrophysiologic study in 15 showed sinus node dysfunction in 12. Atrial flutter was inducible in all patients, and 13 had > 1 flutter configuration. Digoxin and a variety of other antiarrhythmic agents (mean 2.7 drugs/patient) were tried with poor results. Only digoxin, amiodarone, flecainide and propafenone showed some benefit when used alone or in combination. Antitachycardia pacemakers were implanted in 16 patients (endocardial 14, epicardial 2) and, with drugs, were useful in 8 (50%). Because atrial flutter was resistant to treatment, right atriectomy was performed in three patients (with benefit in two, one death), successful radiofrequency catheter His bundle ablation in one patient and catheter ablation of atrial flutter in three patients (two failed, one partial success). One patient underwent heart transplantation, and two died suddenly. Another died of complications after an elective epicardial pacemaker replacement procedure. CONCLUSIONS: Atrial flutter after the Fontan procedure is difficult to control. Aggressive drug and antitachycardia pacemaker therapy help about half of the patients. When these measures fail, other options, such as atriectomy, His bundle ablation or catheter ablation of atrial flutter, need consideration. The risk of sudden death justifies the use of such aggressive treatment methods.

Adolescent↗
PubMed1994

Effect of beta-adrenergic stimulation on the QT interval of children with syncope.

The effect of intravenous bolus doses (0.25, 0.5, 1.0 microgram) of isoproterenol on the QT and RR intervals was reviewed in a group of 34 children undergoing autonomic testing for syncope. Twenty-one patients had a positive orthostatic test and 13 were negative. The two groups (positive and negative) were compared. Baseline QT and RR intervals were similar. The RR interval was shortened by isoproterenol in both groups. Isoproterenol shortened the QT interval in the negative group (as seen in normal persons), but produced QT prolongation in the positive group, although neither reached statistical significance when compared to baseline within the respective group. Comparing the values for RR and QT at each dose of isoproterenol (including baseline) between the two groups showed a significant difference in the QT interval after the 1.0-microgram dose of isoproterenol. Thus children with orthostatic positive neurocardiogenic syncope showed a different QT response to beta-adrenergic stimulation. This lends support to the theory of altered beta-adrenergic sensitivity being present in children with neurocardiogenic syncope.

Adolescent↗
PubMed1994

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia in children.

Radiofrequency (RF) catheter ablation has been widely used in the treatment of cardiac arrhythmias. In atrioventricular nodal reentrant tachycardia (AVNRT), the experience has been predominantly in adults. The cardiac electrophysiological records of 18 consecutive children undergoing RF catheter AV node modification for AVNRT were reviewed. The patients (10 females, 8 males) were 8.2-17.9 years of age (mean 13.6 +/- 3.0), weight 15.2-88.1 kg (mean 52.2 +/- 20.8), and height 103-190 cm (mean 157.1 +/- 21.7). Thirteen were on antiarrhythmic medications (1-3, average 1.5 drugs/day). All drugs were discontinued 48 hours prior to the ablations. The procedures were performed under sedation and local anesthesia. Pre- and post-AV node modification electrophysiological studies were performed in all procedures. The 18 patients underwent a total of 25 procedures (1.39 +/- 0.61 per patient): the anterior approach aimed at the antegrade fast pathway in the first four patients and the posterior approach aimed at the slow pathway in the remainder. The number of energy applications was 8-54 (19.8 +/- 10.7) per procedure. The maximum energy used in each procedure was 30-50 watts (33.8 +/- 8.4). The average energy was 24-50 watts (33.0 +/- 6.8). The fluoroscopy time was 7.1-73.4 minutes (29.9 +/- 20.0) per procedure, for a total catheterization time of 228-480 minutes (300.3 +/- 59.1). Preablation spontaneous or induced AVNRT (cycle length 310.4 +/- 55.0 msec) was seen in all except one who had the arrhythmia (cycle length 270 msec) on surface ECG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Immunosuppressive treatment for myocarditis and borderline myocarditis in children with ventricular ectopic rhythm.

OBJECTIVES: To ascertain the responsiveness to immunosuppressive treatment of myocarditis and borderline myocarditis in children with ventricular ectopic rhythm (that is, all ventricular arrhythmia except benign premature ventricular contractions). To determine the impact of the diagnostic information provided by an endomyocardial biopsy specimen in these patients. BACKGROUND: The therapeutic value of performing an endomyocardial biopsy in children with ventricular ectopic rhythm is not established. In turn, the treatment of myocarditis with immunosuppressive drugs is also controversial. METHODS: The case notes and endomyocardial biopsy findings of all children with ventricular ectopic rhythm and a biopsy diagnosis of myocarditis were reviewed. RESULTS: Ten (14%) of 69 patients with ventricular ectopic rhythm and an anatomically normal heart had histological evidence of myocarditis or borderline myocarditis. Eight patients received corticosteroids and efficacy was judged by regular 24 hour Holter monitoring. Total resolution of arrhythmia was seen in four, improvement in two, and no change in two patients. At follow up (8-39 months, mean 22 months), arrhythmia recurrence was seen in the two patients who showed an improvement but not resolution during treatment. Both received azathioprine with further reduction in ectopy rates. Patients who responded to treatment were symptomatic (six of six patients) at presentation compared with those who did not respond to treatment (none of two patients) who were not symptomatic. Five patients had a repeat biopsy specimen taken which confirmed histological improvement. CONCLUSIONS: Steroid treatment seems to benefit a subset of children with ventricular ectopic rhythm and a biopsy diagnosis of myocarditis or borderline myocarditis. Because it can identify a treatable cause for the ventricular arrhythmia, endomyocardial biopsy is a valuable investigation in these patients.

Adolescent↗
PubMed1994

Developmental electrophysiology of encainide and its major metabolites on the Purkinje fiber action potential.

OBJECTIVE: With clinical data suggesting that neonates may be more prone to developing electrophysiologic side effects from encainide, this study investigates the in vitro developmental electrophysiologic effects of encainide and its major metabolites on the action potential parameters of the canine cardiac Purkinje fiber. METHODS: With standard microelectrode techniques, the in vitro tonic and rate-related effects of encainide, and its major metabolites (3-methoxy-4-hydroxy encainide, MODE, and O-dimethyl encainide, ODE) were investigated using mature and immature canine cardiac Purkinje fibers. RESULTS: The significant developmental differences in the effects of these compounds on the canine Purkinje fiber illustrated in this study are: (1) 1 x 10(-6) M encainide depresses Vmax in neonatal Purkinje fibers, yet not in the adult. (2) 1 x 10(-6) M MODE lengthens APD90 in the neonate, yet it has no substantial effect in the adult. (3) 1 x 10(-6) M ODE shortens APD90 in the adult, yet it has no appreciable effect on the neonate. (4) Rate-related effects of encainide and ODE are more pronounced in adult Purkinje fibers. CONCLUSION: In contrast to other in vitro studies on class I antiarrhythmic agents, neonatal canine Purkinje fibers seem to be more sensitive than the adult to the tonic depolarization depressant effect of encainide. This in vitro sensitivity parallels clinical experience with the drug in neonatal patients. Although encainide is no longer available for clinical use, these findings highlight the fact that the immature conduction system may show markedly different sensitivities to different class I agents despite the fact that these agents share similar qualitative pharmacologic properties.

Action Potentials↗
PubMed1993

Driving safety among patients with automatic implantable cardioverter defibrillators.

OBJECTIVE: To determine the driving behavior of patients following the placement of automatic implantable cardioverter defibrillators (AICDs). SUBJECTS AND DESIGN: Forty patients with AICDs (33 men, seven women; mean age, 62.7 years) responded to a questionnaire designed to ascertain driving behavior after hospital discharge. RESULTS: Despite medical advice never to drive again, 28 patients (70%) resumed driving, with the majority doing so by 8 months after AICD implantation. Of these, 11 (40%) identified themselves as the primary driver in their household. Fourteen (50%) drove daily. Two (7%) were driving and continued to drive during discharge of their AICDs. Twenty-five (91%) reported that they felt comfortable and safe while driving. CONCLUSION: A majority of patients with AICDs continue to drive after a proscription of this activity by health care workers.

Automobile Driving↗
PubMed1993

"Superimposition" digital subtraction angiography: evaluation of total anomalous pulmonary venous connection.

Total anomalous pulmonary venous connection (TAPVC) has a relatively high surgical mortality, especially the infracardiac variety. A small left atrium may limit postoperative cardiac output. Superimposition of digitally subtracted angiographic (DSA) images may be used to define pulmonary venous anatomy, left atrial size, and its spatial relationship to the common pulmonary vein. The technique for acquiring superimposed digitally subtracted images and the results of two cases with infracardiac TAPVC are presented. We have found that this superimposition technique is easily performed and may provide important preoperative information in infants with TAPVC.

Angiography, Digital Subtraction↗
PubMed1993

Histologic study of chronic catheter cryoablation of atrioventricular conduction in swine.

To evaluate the efficacy of catheter cryoablation, we studied histologic changes of the atrioventricular (AV) junction in eight pigs 6 weeks after cryoablation of central conducting tissue. Cryothermia at -60 degrees C was applied to the AV junction through an 8F or 11F cryocatheter with no electrode and was maintained for 3 minutes after complete AV block was obtained. Six weeks later, gross inspection revealed a distinct, oval-shaped scar 5 to 8 mm in length along or above the septal leaflet of the tricuspid valve in each animal. Microscopically, ablated sites were discrete and were replaced by dense connective tissue with no signs of chronic inflammation. Neovascularization was often seen in scar tissue, and small branches of coronary vasculature within lesions appeared patent with mild intimal proliferation. Ablated lesions involved a small area of the summit of the muscular interventricular septum in three animals, but lesions were never found in the base of the aortic wall or aortic valve. The proximal AV conduction system, either the penetrating bundle or a portion of the AV node, was ablated in all five animals with complete AV block. Three animals that did not maintain complete AV block showed scar formation in the atrial septum above the AV node or penetrating bundle; two of these lesions had small islands of viable atrial myocardium embedded within scar tissue. Catheter cryoablation can produce lesions as effectively as those created during open-heart surgery and is a possible procedure for treatment of intractable supraventricular tachycardia. Improvements in technique or in the cryocatheter may be needed to create more reliably located and homogeneous scar.

Animals↗