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Biomedical subjects

P C Gillette

Publications and source records attributed to P C Gillette.

At least 19 recordsLinked to original sources
PubMed1992

Radiofrequency catheter ablation of incessant, medically resistant supraventricular tachycardia in infants and small children.

OBJECTIVES: This study retrospectively evaluates initial experience with radiofrequency catheter ablation in a group of seven infants and small children with a history of incessant, medically resistant supraventricular tachycardia. METHODS: Before attempted catheter ablation, all patients had had unsuccessful conventional medical therapy (with digoxin or propranolol, or both) and, in addition, each continued to have daily episodes of supraventricular tachycardia while taking amiodarone or a class IC antiarrhythmic agent alone or in combination. The average patient age was 10 months (range 1 to 27) and the average patient weight was 6 kg (range 3 to 13). Electrophysiologic diagnosis included reentrant supraventricular tachycardia in six patients and atrial ectopic tachycardia in one patient. RESULTS: These seven patients underwent a total of nine catheter ablation procedures. The atrial approach to ablation was employed in eight of the nine procedures. Overall, radiofrequency catheter ablation was totally successful in five of the seven patients, partially successful in one patient and unsuccessful in the remaining patient. The combination of radiofrequency catheter ablation and surgical ablation was successful in controlling tachycardia in all patients; with at least 5 months of follow-up study, no patient has had a recurrence of supraventricular tachycardia or reappearance of a delta wave. CONCLUSIONS: Surgical ablation of arrhythmogenic substrates in the pediatric age group, although rarely indicated, has been found in the past to be safe and effective. Our initial experience with radiofrequency catheter ablation in infants and small children demonstrates that this procedure is a promising nonpharmacologic therapeutic alternative to surgical ablation.

Catheter Ablation↗
PubMed1992

The developmental electrophysiologic effects of moricizine HCl on the canine cardiac Purkinje fiber.

Using standard microelectrode techniques, the developmental cellular electrophysiologic effects of moricizine HCl on adult and neonatal canine Purkinje fibers were studied. Steady state and rate-related changes in the transmembrane action potentials produced by moricizine HCl in both age groups were characterized and compared. Also, the rate of barium-induced abnormal automaticity before and after drug was also investigated in neonatal and adult Purkinje fibers. The major findings of this study are as follows. (1) The steady state and rate-related depressant effects of moricizine HCl on Vmax were similar in both age groups. (2) Moricizine HCl shortened APD90 in the adult fibers to a greater extent than in the neonate. (3) The concentration of moricizine HCl required to significantly reduce the rate of abnormal automaticity was less in the neonate than in the adult. The effect of moricizine HCl on APD90 of individual Purkinje fibers is influenced both by their control APD90 value as well as by maturational factors. It is less clear whether developmental differences in the effects of moricizine HCl on abnormal automaticity are solely a result of differences in control rates of abnormal automaticity between the two age groups.

Action Potentials↗
PubMed1992

Adenosine's effectiveness in long RP' re-entrant tachycardia: additional evidence of the decremental qualities of the retrograde limb.

Adenosine's ability to terminate atrioventricular (AV) re-entrant supraventricular tachycardia is well documented. Typically, termination occurs as a consequence of transient conduction block in the atrioventricular node, a tissue with decremental qualities. However, the atrioventricular node is not always the site of action when adenosine is used on the re-entrant types of long RP' tachycardias. These tachycardias are, in part, characterized by the decremental qualities of the retrograde limb of the tachycardia circuit, which, in turn, are typically exemplified by retrograde Wenckebach during ventricular (VVI) pacing during intracardiac electrophysiology studies. This case report involves adenosine's ability to block conduction in the retrograde limb of the permanent form of junctional reciprocating tachycardia to provide further evidence as to the AV "nodelike" decremental qualities of this limb.

Adenosine↗
PubMed1992

Subcutaneous lidocaine affects inducibility in programmed electrophysiology testing in children: a follow-up study.

Invasive cardiac electrophysiology testing during cardiac catheterization requires local anesthesia at the point of entry for the catheters. Frequently, lidocaine is employed for this purpose. A prospective study completed in 1990 indicated that subcutaneous administration of lidocaine adversely influenced the inducibility of arrhythmias in pediatric patients. Upon completion of that study, lidocaine concentration was reduced from 1% to 0.5%, and extra caution was taken to avoid deep penetration during administration. A follow-up, prospective study was performed to evaluate inducibility under these changed conditions. Because the depressant effect of lidocaine on inducibility was age- and weight-related, the second study group was required to have statistically indistinguishable age and weight distributions from the first group to eliminate these variables as factors in inducibility. A total of 177 subjects were collected in the second group before a periodic random computer match with the first group produced 99 individuals with the required age and weight distributions. Analysis of the electrophysiology tests in the second study revealed that: (1) incidence of inducibility was higher in the second group (58 of 99 versus 43 of 99, p < 0.05); (2) average lidocaine dose per kilogram was lower (1.8 mg/kg versus 3.28 mg/kg, p < 0.0001); (3) average lidocaine serum concentration was also lower (0.58 micrograms/ml versus 1.47 micrograms/ml, p < 0.0003); (4) in contrast to the first study, neither lidocaine dose nor serum concentration had any effect on inducibility. We conclude that the new procedures for lidocaine administration effectively removed lidocaine as a factor in inducibility.

Adolescent↗
PubMed1992

Life-threatening postoperative junctional ectopic tachycardia.

Junctional ectopic tachycardia developed in an infant after intraatrial repair of transposition of the great arteries. He failed to respond to medical management and, in moribund condition, underwent His bundle cryoablation. He survived and ultimately did well. Junctional ectopic tachycardia is not uncommon after open heart operations in children and may be lethal. Its genesis, diagnosis, and treatment are now well enough understood to allow successful treatment of nearly all patients.

Atrioventricular Node↗
PubMed1992

Atrioventricular pacing in congenital heart disease.

We have attempted to optimize cardiac performance in patients with congenital heart disease requiring artificial pacing by using pacemakers capable of both sensing and pacing both the atrium and the ventricle (DDD). We reviewed our results with 88 patients receiving DDD devices to determine the safety and dependability of these devices in children. Age ranged from 1 hour to 25 years. Endocardial leads were used in 68 patients, whereas epicardial leads were used in 20 patients. Previous cardiac procedures had been done in 30 patients. There were nine deaths but none due to pacemaker malfunction. Endocardial leads functioned better than epicardial leads. Ninety-eight percent of patients with endocardial leads and 62% of patients with epicardial leads were maintained in the DDD mode. Complications were infrequent and all were corrected without long-term sequelae. The DDD mode may offer considerable benefits to children who require artificial pacing. Our data allow us to conclude that most children can be paced safely and dependably in the DDD mode.

Adolescent↗
PubMed1992

Cardiomyopathy and myocarditis in children with ventricular ectopic rhythm.

OBJECTIVE: The objective of this study was to evaluate the histologic features of the myocardium in children with abnormal ventricular ectopic rhythm but a structurally normal heart. BACKGROUND: Abnormal ventricular ectopic rhythm in children with a structurally normal heart is an uncommon but serious condition. Previous studies in adults with these findings have shown that approximately 10% have "primary electrical disease" and that 40% to 100% of these have abnormal histologic findings. METHODS: Endomyocardial biopsy samples were obtained prospectively in 33 subjects presenting with ventricular ectopic rhythm but a structurally normal heart by physical examination and noninvasive studies. Biopsy specimens were evaluated for histologic changes consistent with dilated cardiomyopathy or myocarditis and these results were compared with noninvasive and invasive clinical findings. RESULTS: Of the 33 subjects, 16 (48%) had normal myocardial histologic features (Group A), 14 (42%) had changes similar to the histologic features seen with idiopathic dilated cardiomyopathy (Group B) and 3 (9%) had lymphocytic myocarditis (Group C). Presenting clinical symptoms, surface electrocardiograms (ECGs), exercise stress testing and electrophysiologic stimulation tests failed to predict the biopsy results. Twenty-four-hour ambulatory ECGs showed a statistical difference between sustained and nonsustained ventricular tachycardia in Group A versus Group B (p less than 0.007), with Group A having more sustained ventricular tachycardia. Left ventricular function measured by fractional shortening on echocardiography did not differ between groups, but left ventricular end-diastolic dimension was greater in the subjects with abnormal histologic findings (Group B) (p less than 0.03). CONCLUSIONS: These results provide evidence that approximately 50% of children with abnormal ventricular ectopic rhythm but a structurally normal heart may have subclinical cardiomyopathy or unsuspected myocarditis.

Biopsy↗
PubMed1992

Surgical management of dysrhythmias in infants and small children.

Surgery for cardiac dysrhythmias is infrequently reported in infants and children as compared with adults. This report reviews 55 infants and small children (age, less than or equal to 5 years) operated on during the interval July 1, 1984 to December 31, 1991 for Wolff-Parkinson-White Syndrome (41), atrioventricular node reentry (two), atrial automatic tachycardia (two), and ventricular tachycardia (nine). Ages ranged from 3 weeks to 71 (mean, 29) months. Associated congenital heart defects were present in five (10%). Indications for surgery included failure of medical therapy, life-threatening dysrhythmias, and more recently, failure of catheter ablation. There were no hospital or late deaths. One patient sustained perioperative central nervous system injury. Surgery was successful in 52 of 55 (94.5%) (Wolff-Parkinson-White, 38/41 (93%); atrioventricular node reentry, 2/2 (100%); atrial automatic tachycardia, 3/3 (100%); ventricular tachycardia, 9/9 (100%). Ventricular function returned to normal in all 12 patients in whom it was abnormal before operation. Thus, surgical ablation is highly successful in the management of various forms of refractory or life-threatening dysrhythmias in infants and small children. Catheter ablation techniques require significant fluoroscopic time, are more difficult in infants, and as yet do not have adequate long-term follow-up. Accordingly, surgery may continue to play a role in this particular group of patients.

Arrhythmias, Cardiac↗
PubMed1992

Cardiac pacing in neonates, infants, and preschool children.

A series of 37 children < 5 years old at pacemaker implant were followed from 1 to 105 months. Five of 37 patients required reoperation for battery depletion while two required reoperation for exit block of epicardial ventricular leads. Each patient paced in the DDD or AAI mode was still in the original mode at the end of follow up.

Cardiac Pacing, Artificial↗
PubMed1992

Right atrial diverticulum presenting as Wolff-Parkinson-White syndrome.

A 7-year-old male presenting with Wolff-Parkinson-White syndrome and tachycardia was suspected by echocardiographic and magnetic resonance imaging evaluation to have an associated pericardial cyst anterior to the right atrium and ventricle. Electrophysiological evaluation demonstrated short antegrade and retrograde accessory connection refractory periods, with inducible orthodromic atrioventricular reentrant tachycardia. Surgical observation revealed a rare congenital right atrial diverticulum bridging the anterior right atrioventricular groove, with the functional accessory connection lateralized to the medial aspect of this structure. Endocardial and epicardial incisions and cryolesions placed along the anterior right atrioventricular groove initially appeared successful, but preexcitation recurred within 4 weeks postoperatively.

Cardiac Pacing, Artificial↗
PubMed1992

Developmental cellular electrophysiologic effects of propafenone on the rabbit atrioventricular node.

Transmembrane recordings and surface electrograms were used to evaluate the influence of propafenone on the cellular electrophysiology of isolated neonatal and adult rabbit atrioventricular node (AVN) preparations. An automatic interval of 863 +/- 82 ms (mean +/- SEM, n = 14) in neonates was found to be significantly shorter than the 1510- +/- 205-ms (n = 12) automatic interval observed in adults. Propafenone in a concentration of 5 x 10(-6) M significantly increased the automatic interval of neonatal pacemakers but not that of the adult preparations. These changes in automaticity produced by propafenone were not dependent on the adrenergic receptor-blocking action of the drug. The pacemaker escape time after overdrive pacing was also shorter in the neonate than in the adult. Propafenone prolonged the escape time of the neonatal tissues but not those of the adult. AVN refractory period, A-H interval, and antegrade Wenckebach rate were comparably increased in a concentration-dependent manner in both age groups. The maximum diastolic potential was decreased by propafenone in the neonatal atrionodal tissue but not in other regions of the AVN and not in any region of the adult AVN. Action-potential duration was increased in all regions of the AVN in both age groups. Action-potential amplitude and maximum upstroke velocity were decreased by propafenone in both age groups. Unlike other excitable tissues of the heart, the action-potential duration of AVN nodal cells increased with decreasing pacing intervals as the pacing interval approached the Wenckebach interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

Pediatric cardiac pacing.

Cardiac pacing in children has undergone many improvements in the last decade. The differences between adult and pediatric pacing have narrowed. Children are no longer being denied pacemakers because of size. This article discusses techniques for pacing pediatric patients successfully that will allow them to lead normal lives.

Adolescent↗
PubMed1992

Sudden cardiac death in the pediatric population.

Sudden death in children as in adults is usually due to cardiac disease. Sudden death in the pediatric population may be divided into the sudden infant death syndrome, sudden death in previously apparently healthy children, and sudden death in patients with known cardiac disease. The sudden infant death syndrome is not proved to be due to a cardiac cause and may well be due to central nervous system and/or pulmonary causes. However, interest remains in the cardiac hypothesis. Recent work from our laboratory shows that screening for prolonged QT interval in normal infants is not likely to detect those prone to sudden infant death syndrome. In children with apparently normal hearts, symptoms of syncope or palpitation should be given close attention. Detailed electrocardiography and echocardiography will detect many, but not all, children with subtle forms of heart disease. Vigorous treatment may prevent sudden death in many of these children. Some sort of screening program should be devised for varsity athletes. Children with congenital heart defects are now, for the most part, corrected early in life, so that the congenital heart defect itself rarely causes sudden, unexpected death. The residua and sequelae of the heart defect and the surgery to repair it, however, may lead to sudden death. Improvements in surgical technique and earlier repair of congenital cardiac defects will ameliorate this problem. Prospective evaluation of postoperative patients and attention to dysrhythmias can prevent sudden deaths in those who are prone to them.

Adolescent↗