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Biomedical subjects

D W Benson

Publications and source records attributed to D W Benson.

At least 127 records · Page 7Linked to original sources
PubMed1982

The electrophysiologic basis and management of symptomatic recurrent tachycardia in patients with Ebstein's anomaly of the tricuspid valve.

Twenty-two patients with Ebstein's anomaly were evaluated because of recurrent tachycardia. A total of 30 accessory pathways were present in 21 of the 22 patients. Twenty-six accessory pathways were of the atrioventricular (A-V) type while four were Mahaim fibers. Multiple accessory pathways were present in eight patients. Twenty-five of the 26 accessory A-V pathways were right-sided, either in the posterior septum (12 pathways) or the posterolateral free wall (13 pathways); one patient with corrected transposition of the great arteries had a left-sided accessory A-V pathway in a lateral free wall location. Patients with accessory A-V pathways had a long minimal ventriculoatrial (V-A) conduction time during reciprocating tachycardia (192 +/- 47 ms) and usually showed a persistent complete or incomplete right bundle branch block morphology. At surgery, preexcitation was invariably localized to the atrialized ventricle. The long V-A conduction time during reciprocating tachycardia appeared to consist of late activation of the local ventricle in the region of the accessory pathway with a further delay occurring before excitation of adjacent atrium presumably due to conduction over the accessory pathway. Accessory A-V pathways were successfully sectioned with no deaths in 13 of 15 patients. On the basis of these data, certain electrocardiographic findings encountered in the study of patients with recurrent tachycardia should point to the possibility of associated Ebstein's anomaly: morphology of the surface electrocardiogram suggesting preexcitation of the right posterior septum or right posterolateral free wall as well as the combination during reciprocating tachycardia of a long V-A interval and right bundle branch block.

Adolescent↗
PubMed1982

Heart block in children. Evaluation of subsidiary ventricular pacemaker recovery times and ECG tape recordings.

To evaluate subsidiary ventricular pacemaker function in 20 children with congenital or surgically induced complete heart block, we measured recovery times following overdrive ventricular pacing. Long-term ECG tape recordings were performed in eight of these children. Ages ranged from 1 month to 17 years. The resting R-R intervals ranged from 595 to 1,740 msec. The ventricles were paced at various cycle lengths of 400 to 1,000 msec with either transvenous electrode catheters or surgically implanted epicardial electrodes. His bundle recordings showed that the site of block did not allow separation of patients with symptoms from those without symptoms. Prolonged recovery times were present in patients with block above the His bundle recording site who had symptoms of syncope or dizziness, as well as in patients who had a wide QRS. However, some asymptomatic patient with heart block above the His bundle recording site also had long recovery times. None of the asymptomatic patients who had ECG tape recordings had paroxysmal tachycardia in more than 300 hours of recordings. However, one symptomatic patient with congenital heart block and a prolonged recovery time had brief episodes of paroxysmal ventricular tachycardia that produced no symptoms at the time of recording. The results suggest that the coexistence of prolonged recovery times and paroxysmal tachycardia may be predisposing factors to the development of symptoms in patients with complete heart block. We believe that further electrophysiologic investigation of this possibility is warranted in patients with heart block.

Adolescent↗
PubMed1982

Onset of atrial fibrillation during antidromic tachycardia: association with sudden cardiac arrest and ventricular fibrillation in a patient with Wolff-Parkinson-White syndrome.

Electrophysiologic evaluation in an 18 year old youth with the Wolff-Parkinson-White syndrome who had a sudden cardiac arrest while playing racquetball revealed two types of paroxysmal reciprocating tachycardia: (1) A normal QRS tachycardia with a short ventriculoatrial (V-A) interval fulfilled the criteria for reentry within the atrioventricular (A-V) node; and (2) a wide QRS tachycardia with a QRS configuration of maximal preexcitation was demonstrated to be the result of an antidromic mechanism. During laboratory study, the wide QRS tachycardia spontaneously degenerated into atrial fibrillation. In the basal state, the shortest R-R interval between preexcited QRS complexes was 270 ms, but after infusion of isoproterenol (1.6 microgram/min intravenously), the shortest R-R interval became 180 ms. Consequently, this electrophysiologic study suggested that evolution of antidromic reciprocating tachycardia into atrial fibrillation with a rapid ventricular response during exercise-induced catecholamine release may have been the mechanism for ventricular fibrillation in this patient.

Adolescent↗
PubMed1982

Mechanisms of regular, wide QRS tachycardia in infants and children.

A regular wide QRS tachycardia was electrocardiographically documented in 32 patients aged 1 month to 18 years. The mechanisms of the tachycardia were evaluated using standard multicatheter electrophysiologic techniques. These mechanisms included (1) orthodromic reciprocating tachycardia with bundle branch aberration (seven patients), (2) antidromic reciprocating tachycardia using single (three patients), or multiple (three patients) atrioventricular connections (Kent bundles), (3) atrial flutter with ventricular preexcitation over accessory connections (eight patients), (4) reciprocating tachycardia using a nodoventricular connection (Mahaim fiber) (five patients), and (5) ventricular tachycardia (six patients). Regular side QRS tachycardias are not rare in pediatric patients. Their mechanisms can be quite complex, and electrocardiographic analysis with respect to QRS configuration, heart rate, or the presence or absence of ventriculoatrial dissociation is not sufficient for diagnostic purposes. Our results show that considerable understanding of the mechanism of regular, wide QRS tachycardias can be obtained by multicatheter electrophysiologic study. Understanding the mechanism is essential in order to make rational use of available therapeutic options.

Adolescent↗
PubMed1982

Evolution of QRS and ST-T-wave body surface potential distributions during the first year of life.

Using a system for obtaining body surface potential distributions from 150 sites on the anterior and posterior torso, 43 body surface maps were evaluated in 31 normal infants, ages 15 hours to 10 months. Serial maps were obtained at 0.6-msec intervals during QRS and at 2.4-4-msec intervals throughout the ST-T wave. We found an orderly evolution of both QRS and ST-T wave maps during the first year of life. In the newborn, the patterns during the latter half of QRS were consistent with early completion of depolarization of the left ventricle and prolonged depolarization of the right ventricle. The patterns changed gradually such that by 5-6 months of age, the maps demonstrated simultaneous effects of both right and left ventricles during the latter half of QRS. By 9 months, the QRS patterns were similar to those of older children and adults. The changes in the ST-T-wave maps were consistent with the idea that age-related changes in the sequence of ventricular activation.

Electrocardiography↗
PubMed1982

Localization of the site of ventricular preexcitation with body surface maps in patients with Wolff-Parkinson-White syndrome.

Forty-nine patients with Wolff-Parkinson-White syndrome, ages 7 weeks to 51 years, were studied with isopotential body surface maps during normal sinus rhythm, atrial pacing or induced atrial fibrillation. The location of the accessory pathway was determined by multicather electrophysiologic study or surgical ablation of the accessory pathway. When fusion was minimized and ventricular activation primarily controlled by a single accessory pathway, the distribution of positive and negative potentials on the anterior and posterior torso during QRS (observed at 40 msec) and the ST segment were an excellent index of the location of the site of the accessory pathway. The relationship between a specific sequence of QRS-T wave body surface maps and a specific preexcitation site was similar from patient to patient in the presence of marked differences in age, size, and different cardiac status due to structural congenital cardiac defects. The localization of the site of the accessory pathway using distributions too early in QRS (before 40 msec) was unreliable because the early distributions varied from patient to patient for the same preexcitation site; however, the potential distributions during the ST segment were both stable and consistent from patient to patient for the same preexcitation site. The presence of significant fusion of ventricular activation initiated via a single accessory pathway and the normal conduction system or via multiple accessory pathways complicated the interpretation of body surface distributions. Thus, one can predict accurately at least seven preexcitation sites by the combined use of QRS and ST-segment body surface maps.

Adolescent↗
PubMed1981

Left atrial myxoma. Is cardiac catheterization essential?

Although uncommon in children, primary cardiac tumors, especially left atrial myxomas, can be cured with surgery. We present our experience with a 12-year old boy with a left atrial myxoma diagnosed by two-dimensional echocardiography who underwent successful surgical resection without prior catheterization. We recommend that all patients suspected of having cardiac tumors undergo echocardiographic evaluation. As this case illustrates, the essential information for surgical management of myxomas can be obtained from two-dimensional echocardiograms, which obviates cardiac catheterization.

Cardiac Catheterization↗
PubMed1981

Absent pulmonary valve syndrome in infancy: surgery reconsidered.

Congenital absence of the pulmonary valve leaflets is generally associated with ventricular septal defect, anular pulmonary stenosis and aneurysmal dilatation of the pulmonary arteries: the absent pulmonary valve syndrome. Symptomatic infants with this syndrome suffer primarily from respiratory insufficiency caused by bronchial compression by the dilatated pulmonary arteries, and have a high mortality rate. Asymptomatic infants are thought to do well, and may have elective surgery late in childhood. Findings in four infants with absent pulmonary valve syndrome are reviewed. One symptomatic infant was successfully treated with closure of a ventricular septal defect and pulmonary arterial plication. One previously asymptomatic infant had a fatal respiratory arrest revealing the complexity of management of infants with absent pulmonary valve syndrome.

Bronchial Diseases↗
PubMed1981

Role of Mahaim fibers in cardiac arrhythmias in man.

Twelve patients with evidence of Mahaim fibers are reported, six with nodoventricular (NV) fibers and six with fasciculoventricular (FV) fibers. All patients with NV fibers had left bundle branch block morphology, and a sustained reentrant tachycardia with this morphology was proved in each case. In three of the six, ventriculoatrial dissociation occurred during tachycardia. We postulate that the mechanism of this tachycardia is a macroreentry circuit using the NV fiber for the antegrade limb and the His-Purkinje system with a portion of the atrioventricular node for the retrograde limb. ECGs of patients with FV fibers were varied, suggesting a functional relation to the right or left side of the septum. No direct relationship of FV fibers to observed arrhythmias could be found.

Adolescent↗
PubMed1980

Accessory atrioventricular pathway in an infant: prediction of location with body surface maps and ablation with cryosurgery.

A 10-month-old infant with multiple muscular ventricular septal defects, congestive heart failure, Wolff-Parkinson-White syndrome, and supraventricular tachycardia is presented. The site of ventricular pre-excitation was predicted by analysis of ST-T wave isopotential body surface maps to be in the posterior free wall of the right ventricle. The site was confirmed by epicardial mapping of the ventricles during surgery. The pathyway was cryoblated and the ventricular defects were closed. The patient has been free of pre-excitation and supraventricular tachycardia for over two years since surgery.

Animals↗
PubMed1980

Closed circle systems. A new direction in the practice of anesthesia.

On the basis of the near-constant uptake of inhalation anesthetics at the alveolar membrane, the large closed-circuit volume which acts as a buffer, and the effect of concentration on uptake, we have evolved a simple and practical technique of closed-circuit anesthesia. After initial high flow wash-in of anesthetic gases into the FRC, a nearly constant slow fresh-gas flow can be maintained.

Anesthesia, Inhalation↗
PubMed1980

Catecholamine induced double tachycardia: case report in a child.

A six-year-old girl with syncope in association with atrial flutter-fibrillation and ventricular tachycardia produced by exercise or emotion is presented. The tachycardias could be reproduced by low-dose isoproterenol infusion and were blocked by high dose propranolol therapy. Catecholamine-induced tachyarrhythmias should be suspected in children with unexplained syncope in association with exercise or emotion.

Atrial Fibrillation↗
PubMed1980

Use of the esophageal lead in the diagnosis of mechanisms of reciprocating supraventricular tachycardia.

Recent studies have emphasized the role of concealed accessory pathways in reciprocating supraventricular tachycardia. Diagnosis has generally required multicatheter electrophysiologic study. We recorded esophageal electrograms during study in 16 patients with reciprocating tachycardia due to reentry using an accessory atrioventricular pathway, and in 12 patients with reciprocating tachycardia due to reentry in the AV node. The interval from onset of ventricular depolarization to earliest atrial activation (V-AMIN), earliest atrial activity on the esophageal lead (V-AESO), and high right atrium (V-HRA) was measured. No patient with RT due to an accessory atrioventricular pathway had a V-AMIN or V-AESO less than 70 ms, or a V-HRA less than 95 ms. In contrast, 11 of 12 patients with reentry in the AV node had V-AESO intervals less than 70 ms. Esophageal recording during reciprocating tachycardia provides a simple screening procedure available to all practicing physicians to exclude the diagnosis of accessory atrioventricular pathways in the genesis of paroxysmal supraventricular tachycardia.

Adolescent↗
PubMed1980

Corrected transposition with severe intracardiac deformities with Wolff-Parkinson-White syndrome in a child. Electrophysiologic investigation and surgical correction.

This is a report of a 10-year-old child who underwent surgery for complex congenital heart disease consisting of corrected transposition of the great vessels, ventricular septal defect, patent ductus arterisus, severe left-sided atrioventricular (AV) valve insuffieicney (Ebstein's deformity) and Wolff-Parkinson-White syndrome. The site of his accessory AV connection was localized preoperatively at a left anterolateral site by isopotential body surface maps and by intracardiac electrophysiologic studies. He successfully underwent surgery for closure of the ventricular septal defect, ligation of the patent ductus arteriosus, replacement of the left-sided AV valve, and interruption of the accessory AV pathway. Unavoidable complete AV block acquired at surgery required subsequent permanent pacemaker therapy.

Cardiac Catheterization↗
PubMed1980

Electrophysiologic evaluation and surgical correction of Wolff-Parkinson-White syndrome in children.

The Wolff-Parkinson-White syndrome is due to a congenital heart malformation that is the result of one or more persistent anomalous atrioventricular pathway(s). While supraventricular tachycardia is the most commonly associated arrhythmia, there is a wide spectrum of associated arrhythmias including fatal ventricular fibrillation. It is now known that surgical ablation of the anomalous pathway(s) can result in complete cure of arrhythmias in some patients. The purpose of this report is to describe the current methods used for the preoperative and operative electrophysiologic evaluation and surgical treatment in children with the Wolff-Parkinson-White syndrome, as illustrated by the case presentation of a normal eight-year-old patient who had ventricular fibrillation.

Cardiac Pacing, Artificial↗