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Biomedical subjects

C L Case

Publications and source records attributed to C L Case.

At least 55 records · Page 3Linked to original sources
PubMed1993

Sonographic assessment of fetal cardiac arrhythmias.

The fetus with an arrhythmia may be at high risk both from the arrhythmia itself and from the condition that provoked it. Incorrect diagnosis and inappropriate or delayed treatment may further compound the hazard. Although echocardiography can specifically identify the arrhythmia, this technique requires very skilled and careful examination by a physician who fully understands how to differentiate optimally between similar-appearing but mechanistically different arrhythmias. Congenital heart disease may also be present and must be evaluated specifically. This report describes ultrasound recording techniques used to diagnose arrhythmias and includes a discussion of M-mode echocardiography, two-dimensional imaging, pulsed Doppler, and color-flow Doppler. It also differentiates specific arrhythmias--premature atrial contractions, ventricular tachycardia, atrial flutter, complete heart block, and supraventricular tachycardia--and presents the optimal diagnostic tools for each.

Arrhythmias, Cardiac↗
PubMed1993

Resolution of atrial standstill in a child with myocarditis.

Atrial standstill is a rare disorder usually seen in adults with extreme myocardial disease. Etiologies described in the literature have included muscular dystrophy, familial amyloidosis, and rarely myocarditis. These etiologies usually lead to permanent atrial standstill and require ventricular pacing. We present a case of an 11-year-old black female who developed atrial standstill secondary to biopsy proven acute necrotizing myocarditis. Absence of atrial function was confirmed by surface electrocardiogram, echocardiogram, and an invasive electrophysiology study. Atrial function returned within 3 days of initiation of methyl-prednisolone. In cases of atrial standstill due to myocarditis, a delay in the placement of a permanent pacemaker with or without a trial of methylprednisolone may prove beneficial.

Acute Disease↗
PubMed1993

Automatic atrial and junctional tachycardias in the pediatric patient: strategies for diagnosis and management.

Unlike supraventricular arrhythmias secondary to reentry, automatic rhythm disturbances in children are rare and more resistant to standard pharmacological therapy. This article reviews strategies for the diagnosis and management of two of the more common pediatric automatic rhythm disturbances, that is, atrial ectopic tachycardia, and junctional ectopic tachycardia. The place of newer nonpharmacological therapy, such as catheter ablation, in the treatment of these entities is beginning to be explored, yet has not been fully delineated. Despite these limitations, there is enough experience with these difficult tachycardias in the pediatric age group to formulate some strategies for optimal diagnosis and management.

Adolescent↗
PubMed1993

Radiofrequency catheter ablation of an accessory atrioventricular connection in a Fontan patient.

Radiofrequency catheter ablation is fast becoming the procedure of choice for the nonpharmacological treatment of atrioventricular connections that are responsible for debilitating tachycardias. We, herein, present a case of reentrant supraventricular tachycardia secondary to an atrioventricular connection in a Fontan patient that was successfully treated with radiofrequency catheter ablation.

Catheter Ablation↗
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

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

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↗
PubMed1991

Atrial antitachycardia pacing in children and young adults.

Atrial antitachycardia pacing was tested in 23 children and young adults. The majority of these patients had had operative repair of congenital cardiac defects and had both bradycardia and tachycardia. Pacemakers were usually implanted by the transvenous technique using bipolar leads. In each patient it was possible to find a tachycardia termination algorithm that successfully converted the tachycardia. In some patients very complex algorithms were necessary. In each patient it was also possible to find an algorithm that successfully differentiated the abnormal tachycardia from sinus tachycardia. Twelve patients required no antiarrhythmic drugs after pacemaker implantation, while 10 patients required one drug and one patient required two drugs. Eight of 23 patients had symptomatic tachycardias that required reprogramming the pacemaker to a different tachycardia termination sequence. Seven patients required reoperations, five for adapter problems and two for infection or erosion. Cardiac function improved in 15 of the 23 patients. Antitachycardia pacing is a viable option for management of tachycardias in children and young adults.

Adolescent↗
PubMed1991

Successful catheter fulguration of the His bundle in a postoperative Mustard patient after unsuccessful fulguration of ectopic atrial foci.

Incessant supraventricular tachycardia (SVT) resistant to pharmacological agents may cause cardiac dysfunction requiring more aggressive therapy. We present the case of a 12-year-old postoperative Mustard patient who developed biventricular heart failure due to an atrial ectopic tachycardia resistant to amiodarone. Using endocavitary direct current fulguration techniques, catheter ablation of the His bundle was successfully performed after unsuccessful attempts at ablation of the ectopic atrial foci. After placement of a permanent transvenous rate responsive ventricular pacemaker, the patient's clinical status and cardiac function improved. Endocavitary fulguration of the His bundle is technically feasible after the Mustard procedure and should be considered for treatment of selective cases of pharmacologically resistant SVT.

Amiodarone↗