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Biomedical subjects

C L Case

Publications and source records attributed to C L Case.

At least 73 records · Page 4Linked to original sources
PubMed1991

Transvenous cryoablation of the bundle of His.

Cardiac dysrhythmias are a prominent cause of morbidity and mortality. Pharmacological treatment is ineffective in a large number of patients and is associated with many serious side effects. Thus, direct treatment of cardiac arrhythmias has been used with increasing frequency. Each form of direct treatment, such as surgical ablation, DC catheter ablation, radiofrequency catheter ablation, laser catheter ablation suffer serious drawbacks. Thus, we investigated the utility of transvenous catheter cryoablation of the bundle of His in five miniature swine, 40-60 lbs. in weight. Complete atrioventricular block was produced in each animal during cryothermia and persisted for 1 hour of observation in four out of five swine. In the fifth animal, 2:1 atrioventricular block within the atrioventricular node persisted for 1 hour of observation. Morphological and histologic examination revealed no dysfunction of capillaries and myofibriles in the atrioventricular node and proximal bundle of His. This potential mode of transcatheter therapy deserves further investigation.

Animals↗
PubMed1991

Developmental electrophysiologic effects of propafenone and 5-hydroxypropafenone on the canine cardiac Purkinje fiber.

Standard microelectrode techniques were used to investigate the in vitro developmental electrophysiologic effects of propafenone and 5-hydroxypropafenone on the adult and neonatal canine Purkinje fiber. The tonic and frequency-dependent depressant effects of these compounds on Vmax and amplitude were similar in both age groups. However, the ability of these compounds to shorten repolarization parameters was more pronounced in the adult. The extent of reduction of abnormal automaticity produced by propafenone was greater in the neonate compared to the adult, and 5-hydroxypropafenone significantly reduced automaticity only in the neonate. The sensitivity of neonatal abnormal automaticity to the effects of these compounds may prove to be important if the use of these agents is to be expanded into the realm of therapy for pediatric automatic rhythms.

Age Factors↗
PubMed1990

Clinical and electrophysiological characteristics of ventricular tachycardia in children with normal hearts.

Characteristics of 18 patients with clinical ventricular tachycardia (VT) and normal hearts documented by physical examination, echocardiography, and angiocardiography were analyzed. There were 13 males and 5 females, aged 1 to 16 years (mean +/- SD, 9.7 +/- 4.8 years). Six patients had hemodynamic instability during VT and the other 12 patients were hemodynamically stable. Two patients (11%) presented with sustained VT and 16 (89%) with episodes of nonsustained VT at varying intervals (3 of 16 with repetitive monomorphic VT). Among 14 patients on whom exercise tests were performed, seven had exercise-induced VT. During electrophysiologic studies, VT was induced in 16 of 18 (89%) (in 13 patients with morphology identical to clinical VT). VT was induced by programmed stimulation (single, double, and burst stimulation of the right atrium or right ventricular apex during sinus rhythm or during pacind for eight beats) in 5 of 18 (28%) patients; with isoproterenol, VT was aggravated spontaneously in 6 of 15 (40%) patients; and during stimulation VT was induced in 8 of 15 (53%) patients. Among patients whose VT was not induced during programmed stimulation, VT was induced with the addition of isoproterenol in 11 of 12 (92%). All 14 patients in follow-up are in stable condition, seven patients with medication and seven without medication. Pediatric patients with normal hearts and clinically detected VT usually have VT induced by programmed stimulation, either with or without isoproterenol stimulation.

Adolescent↗
PubMed1990

Surgical treatment of dysrhythmias in infants and children.

The recognition of medically refractory dysrhythmias in children has necessitated the use of more invasive nonpharmacologic therapies. The role of ablative surgery in the management of pediatric rhythm disturbances is presented.

Arrhythmias, Cardiac↗
PubMed1990

Successful treatment of congenital atrial flutter with antitachycardia pacing.

Congential atrial flutter is a condition that rarely requires chronic pharmacological therapy. An unusual case of congenital atrial flutter is described which was resistant to medical therapy, yet responded well to antitachycardia pacing. While most experience with antitachycardia pacing in pediatrics has been with the postoperative congenital heart patient, patients such as the one described with unscarred atria may prove to be the most suitable pediatric candidates for this pacing modality.

Atrial Flutter↗
PubMed1990

Computer-enhanced mapping of activation sequences in the surgical treatment of supraventricular arrhythmias.

Surgical treatment of accessory pathways and ectopic foci requires accurate information on the physical locations of the arrhythmogenic substrates. Although electrophysiology studies during cardiac catheterization frequently provide accurate and reliable data, the physical locations of the sites to be ablated must be verified in situ by electrical activity mapping. We have developed a microcomputer-based system that facilitates creation of electrical activity maps, supplanting the manual method formerly used. Signals produced by mapping and reference electrodes, as well as cardiac diagrams with grid coordinates and times, are presented on a monitor in formats that are easily interpreted by the surgeon and cardiologist. The system is rapid, accurate, and reliable, and has reduced the time required to localize conduction abnormalities from 30 to 45 minutes for the manual method, down to an average of 12 minutes per case. The system is simple to operate, requiring only minimal training. All of the components of the system are commercially available; no specialized hardware is required.

Adolescent↗
PubMed1990

Neonatal pneumomediastinum with isolated mitral obstruction.

While mediastinal air accumulation in the ventilated newborn is usually a benign entity, tension pneumomediastinum can embarrass both respiratory and cardiac function. A case of isolated left ventricular inflow obstruction caused by a pneumomediastinum in a premature infant is described that resolved with high frequency ventilation. The development of pneumomediastinum and haemodynamic compromise in a premature infant warrants echocardiographic examination.

Humans↗
PubMed1989

Management strategies for surgical treatment of dysrhythmias in infants and children.

To elucidate the role of surgery in the management of refractory pediatric dysrhythmias, the investigators' 1987 experience with this therapy was reviewed. Sixteen patients (8 male, 8 female) had surgery. Age ranged from 3 months to 21 years (mean 7.7 years) with 2 being younger than 1 year of age. Eight patients had Wolff-Parkinson-White syndrome with supraventricular tachycardia (SVT), 6 had SVT alone and 2 had ventricular tachycardia. Patient symptoms fell into 3 distinct categories. Nine patients had frequent non-life-threatening tachycardia episodes despite aggressive medical management, 4 patients had life-threatening symptoms either related to frequent tachycardia episodes or due to side effects of drugs and 3 patients had minimal tachycardia symptoms but were judged to be at risk for sudden death. The mechanisms of the tachycardias included reentrant SVT using an accessory atrioventricular connection in 9, the permanent form of junctional reciprocating tachycardia in 2, atrioventricular node reentrant SVT in 2, atrial ectopic focus in 1 and ventricular ectopic foci in 2. Ablation techniques involved either surgical dissection or cryoablation of the arrhythmogenic substrates. There was no surgical mortality and follow-up shows 15 of 16 patients to have had no recurrence of symptomatic tachycardia without any therapy. Based on this experience, management strategies for surgical control of recalcitrant pediatric dysrhythmias are proposed. Surgery for infant dysrhythmias should be performed only for life-threatening symptoms. Beyond the first year of life, after failing 2 medications, surgical options for SVT should be considered. For patients with ventricular tachycardia, aggressive medical management with class II, IC and III agents should be attempted before surgical therapy.

Adolescent↗
PubMed1989

New antiarrhythmic agents in pediatrics.

This article reviews recent developments in the pharmacologic management of arrhythmias in children and provides specific information about six newer antiarrhythmic agents. With the current increase in recognition, frequency, and complexity of rhythm disturbances in children, pediatricians can expect to encounter children on these antiarrhythmic medications in their practices with increasing frequency.

Action Potentials↗
PubMed1989

Problems with permanent atrial pacing in the Fontan patient.

Transvenous atrial pacing is the preferred method for control of both brady and tachyarrhythmias in the postoperative pediatric patient with normal atrioventricular conduction. We reviewed our experience with the use of permanent atrial pacing for the control of bradycardia and tachycardia in the Fontan patient. We then compared this pacing experience to atrial pacing data compiled for postop Transposition of the Great Arteries (TGA) patients. Out of twenty-five Fontan patients followed at the Medical University of South Carolina, six patients have had atrial arrhythmias necessitating pacing (24%). Underlying congenital heart disease included tricuspid atresia physiology in three and single ventricle in three. The indications for atrial pacing was brady-tachy syndrome in four patients and sick sinus syndrome in two. Pacers were inserted immediately post-op in three patients and 1.5 years, 2 years, and 8 years post Fontan in the other three. These six patients have required a total of nine pulse generator implantations. Five of the nine pacers were inserted transvenously and four via thoracotomy. In contrast to our experience with permanent atrial pacing in post TGA patients, dysrhythmia control with atrial pacing in the Fontan patient has been more difficult to achieve. The Fontan patients have a higher incidence of symptomatic dysrhythmias, hospitalizations, and antidysrhythmic medication requirements after pacer insertion. Implantation thresholds of the Fontan patients are higher than those of the transposition group. While successful atrial demand pacing is attainable in both groups, antitachycardia pacing is more reliable in the post-op TGA patient. The Fontan procedure seems to present a new set of obstacles for successful atrial pacing in the pediatric post-op patient.

Arrhythmias, Cardiac↗
PubMed1989

Continuity of care. Development and implementation of a shared patient data base.

Although the inpatient Oncology Unit, the Medical Oncology Clinic, and Radiation Oncology provided care for many of the same patients, there was no mechanism for sharing nursing information, and little colleague input from one area to another. In order to meet this need, a nurse from each of the clinic areas was added to the inpatient unit's Patient Care Evaluation Committee. Working through this committee, these nurses developed an Inpatient/Outpatient Data Flow Sheet, which could be initiated in any oncology area to implement information flow when a patient was to be seen in a different setting. It proved to be an effective tool. The flow sheet, along with our rationale, was then presented for consideration as a computerized program to be used between the three areas. After careful investigation, it was approved. This provided the oncology areas with the first data storage capability for nursing in the hospital. It offered oncology nurses in distinct and separate areas access to obtain and update information on shared patients. This manuscript will focus on the computer program and the data base designed for the oncology department and its impact on nurses and patients.

Cancer Care Facilities↗