PubMed Health⌕ Search

Biomedical subjects

M R Gilbert

Publications and source records attributed to M R Gilbert.

35 records · Page 2Linked to original sources
PubMed1987

Frequency, diagnosis and clinical characteristics of patients with multiple accessory atrioventricular pathways.

Multiple accessory atrioventricular (AV) pathways were documented in 52 of 388 patients (13%) who underwent detailed electrophysiologic evaluation. Multiple AV pathways were identified during intraoperative mapping or electrophysiologic study by different patterns of ventricular preexcitation during atrial fibrillation, flutter or atrial pacing with different delta-wave morphologic and ventricular activation patterns; different sites of atrial activation during right ventricular pacing or orthodromic reciprocating tachycardia; or preexcited reciprocating tachycardia using a second pathway as the retrograde limb of the tachycardia. A logistic model was used to determine which clinical, electrocardiographic and electrophysiologic variables were associated with multiple AV pathways. Right free-wall and posteroseptal accessory AV pathways were more common in patients with multiple AV pathways and were frequently associated. Multivariate logistic regression identified Ebstein's anomaly, and a history of preexcited reciprocating tachycardia as significant variables (p less than 0.0001). Pathway location was not subjected to statistical analysis because of confounding variables.

Adolescent↗
PubMed1987

Value of the 12-lead electrocardiogram in discriminating atrioventricular nodal reciprocating tachycardia from circus movement atrioventricular tachycardia utilizing a retrograde accessory pathway.

The value of the 12-lead electrocardiogram for distinguishing atrioventricular (AV) nodal reciprocating tachycardia from circus movement AV tachycardia utilizing a retrograde accessory pathway was studied in 100 patients with narrow QRS complex tachycardia. Intracardiac electrograms showed AV nodal reciprocating tachycardia in 40 patients and circus movement AV tachycardia in 60. The 12-lead electrocardiograms recorded during tachycardia were randomly sorted and reviewed by 4 experienced cardiac electrophysiologists who were blinded to the diagnosis associated with each tracing, the relative proportion of each arrhythmia and the hypotheses to be tested. Each reviewer was asked to indicate the location of the P wave relative to the QRS complex, electrical axis of the P wave in the frontal and horizontal planes and presence or absence of QRS alternation, and to interpret the most likely mechanism. The performance of published electrocardiographic criteria to differentiate AV nodal reciprocating tachycardia from circus movement AV tachycardia was evaluated. The overall accuracy of the reviewers' interpretations was 75%, similar to the accuracy of the predefined criteria when applied by these observers (71% correct, difference not significant). Interobserver agreement of reviewer interpretations was 76% and the intraobserver agreement was 78%. Features associated with circus movement AV tachycardia by univariable analysis were P waves after the QRS complex, faster tachycardia rates and QRS alternation. Multivariable analysis showed that only the location of the P wave relative to the QRS complex was independently associated with the mechanism of tachycardia (p = 0.002). QRS alternation was found by multivariate analysis to be associated with the rate but not the mechanism of the tachycardia.

Diagnosis, Differential↗
PubMed1987

Comparison of survival of amiodarone-treated patients with coronary artery disease and malignant ventricular arrhythmias with that of a control group with coronary artery disease.

Although amiodarone is effective in the treatment of ventricular arrhythmias, it is associated with serious toxic effects. In addition, the prognosis of patients with malignant ventricular arrhythmias and coronary artery disease treated with amiodarone remains poor. The survival of 54 consecutive patients with angiographically documented coronary artery disease and symptomatic ventricular tachycardia or ventricular fibrillation treated with amiodarone was compared with that of 5,125 medically treated patients with coronary artery disease. The amiodarone group was older, with worse left ventricular function and more peripheral and cerebrovascular disease. The 1 year survival probability was 0.73 for the amiodarone group and 0.94 for the control coronary artery disease group. At 2 years of follow-up, the survival probabilities were 0.60 and 0.90 for the amiodarone and the control group, respectively. When the survival curves were adjusted for group differences in baseline prognostic characteristics (integrated as a previously published hazard score), there was no difference in the prognosis of the two groups. These findings suggest that treatment with amiodarone of malignant ventricular arrhythmias associated with coronary artery disease maintains patients on an underlying survival curve determined by the degree of myocardial dysfunction, clinical characteristics and coronary anatomy, and that amiodarone does not have a deleterious effect on survival.

Aged↗
PubMed1987

Atrial lead perforation: a case report.

We report a patient in whom a chronic atrial lead perforated the right atrium and the right lung. This resulted in an hemopneumothorax and pneumomediastinum which was clearly documented by a chest computerized tomographic scan. The finding of pneumomediastinum should suggest atrial lead perforation. The utility of the chest computerized tomographic scan in diagnosing lead perforation is well illustrated by this case.

Aged↗
PubMed1986

Computer-assisted intraoperative mapping of the entire ventricular epicardium in the Wolff-Parkinson-White syndrome.

Intraoperative mapping with a hand-held, roving electrode requires a sustained rhythm lasting 5 to 10 minutes. To overcome this limitation, a computerized mapping system that records from 60 epicardial electrodes simultaneously was used to study 16 patients with Wolff-Parkinson-White syndrome. A sock containing 6 rows of electrodes arranged concentrically from base to apex was place over the ventricles. The total time from placing the sock to analyzing the most basal row of electrode recordings was 5 minutes. A 39 X 44-mm plaque containing 56 electrodes was than placed across the atrioventricular (AV) groove for detailed simultaneous mapping of the ventricle and atrium in the preexcited region identified from the most basal row of sock electrodes. During plaque placement and recording, the remaining sock recordings were analyzed and a complete isochronal epicardial map was drawn. The plaque recordings were then analyzed. This technique rapidly detects early activation at the AV groove as do other computer systems using only a band of electrodes around the AV groove. Also, complete epicardial mapping supplied important additional information. One patient with a posterior paraseptal accessory pathway had ventricular epicardial breakthrough below the strip recorded by the AV band. When more than 1 early activation site was present along the AV groove, complete maps allowed multiple pathways to be differentiated from normal activation fronts ascending from the bundle branches. Complete epicardial maps allowed the study of rapidly changing or short-lived electrical events including isolated premature impulses, initiation and termination of reciprocating tachycardia by pacing, entrainment and changing degrees of fusion created by pacing during reciprocating tachycardia, and ventricular responses during atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Incidence and nature of neurologic problems in patients with solid tumors.

The medical records of all patients admitted to the solid tumor service of the Johns Hopkins Oncology Center over a three-month period were reviewed to determine the incidence and nature of major neurologic problems on the inpatient service of a university-based comprehensive cancer center. Seventy-four of 162 patients (46 percent) admitted during this time had tumor invading or compressing the nervous system, pain, seizures, or alteration in mental status. The most common problems were pain (34 patients) and altered mental status (25 patients). The evaluation or treatment of a neurologic problem constituted the second most common reason for admission to this inpatient oncology unit. Neurologic problems will soon be the most common reason for hospital admissions in patients with disseminated cancer as a result of changes in patterns of health care delivery and improvements in systemic therapy and supportive care.

Adult↗
PubMed1986

Characterization of retrograde conduction by direct endocardial recording from an accessory atrioventricular pathway.

Accessory pathway electrograms are rarely recorded in patients with Wolff-Parkinson-White syndrome. In one patient, during electrophysiologic study, simultaneous local ventricular (V) accessory pathway (AP) and atrial (A) deflections were recorded during bipolar catheter endocardial mapping over the pathway. Analysis of changes in electrographic intervals during performance of the ventricular extrastimulus technique allowed characterization of the retrograde conduction properties of the pathway. As coupling intervals were decreased, an initial increase was seen in the AP2A2 interval with subsequent ventriculoatrial block between the accessory pathway and atrium. When coupling intervals were further decreased, the V2AP2 interval lengthened with ultimate block between the ventricle and accessory pathway. These findings support the concept of impedance mismatch as the cause of conduction block in accessory pathways with the distal junction of the accessory pathway being the most vulnerable.

Adult↗
PubMed1985

Frequency-dependent effects of verapamil on atrioventricular nodal conduction in man.

We sought to determine if verapamil induces frequency-dependent prolongation of atrioventricular nodal conduction in 10 consecutive patients studied in the electrophysiology laboratory. We used a maintenance infusion of verapamil designed to produce plasma concentrations of verapamil in the "therapeutic" range and that did not alter heart rate or blood pressure significantly. Frequency-dependent prolongation of atrioventricular nodal conduction (AH interval) was demonstrated in all 10 patients (p less than .001), and no change in HV conduction time with decreasing cycle length was noted in any patients while receiving verapamil. Two patterns of use-dependent response were seen. In four patients frequency-dependent prolongation of the delta(AH) interval [delta(AH) = AHverapamil - AHcontrol at a given cycle length] was seen with each decrement in pacing cycle length. In six patients frequency-dependent prolongation of the delta(AH) interval was not manifest until the fifth to eighth pacing cycle length tested. There was no association between the pattern observed and the initial heart rate or AH interval. After an abrupt change in pacing cycle length, the kinetics of delta (AH) interval prolongation were rapid; equilibrium was achieved by five to eight pulses in all patients. There was no correlation between the magnitude of prolongation of the AH interval noted at a particular cycle length and the concentration of verapamil during the maintenance infusion. These results indicate that verapamil causes use-dependent prolongation of atrioventricular nodal conduction in man.

Atrioventricular Node↗
PubMedDate not supplied

Metastatic brain tumors: diagnosis, treatment, and nursing interventions.

Metastatic tumors are by far the most common cause of brain cancer, with an incidence rate higher than all other types of primary brain tumors combined. Cancer cells can spread to the brain from other sites via the blood supply, lymphatic system, or direct extension. Neurologic symptoms, which are dependent on tumor location, often include headache, weakness, or cognitive deficits. Although the standard of care is evolving, treatment often includes some combination of surgery and radiation therapy. Newer treatments, including radiosurgery and novel chemotherapy approaches, currently are being investigated. These treatment advances have markedly altered the prognosis for patients with brain metastases. Consequently, the status of the systemic components of the malignancy often may be the determinant of outcome.

Anticonvulsants↗
PubMedDate not supplied

Analgesic decision-making skills of nurses.

Administration of analgesics is a common nursing intervention for providing pain relief to patients with cancer. A sample of 177 nurses participated in a study to examine their decision-making skills when analgesic orders were changed. Nurses were given four clinical vignettes and reference materials to assist them in responding to the vignettes. Twenty-six percent of 708 responses provided by the nurses were answered correctly. Twenty-nine percent of the sample answered all four vignettes incorrectly. The majority (44%) answered only one vignette correctly. No statistically significant differences were found between correct answers and type of work setting, academic preparation, number of patients with cancer cared for per week, number of years employed as a nurse, recent clinical experience with the analgesics used in the vignettes, or the use of reference materials. These findings raise concerns that patients requiring analgesics may not receive an amount that adequately relieves their pain or avoids unnecessary toxicity.

Clinical Competence↗
PubMedDate not supplied

Management of seizures in the adult patient with cancer.

Seizures are a frequent neurologic complication of cancer. Seizures may develop as a consequence of direct extension of cancer into the brain or surrounding meninges, an underlying metabolic imbalance from treatment or the tumor, or the neurotoxic effects of cancer therapy. Emergency treatment is essential for status epilepticus and seizures that occur frequently to prevent permanent neurologic sequelae. In all cases, a diagnostic evaluation is required to discover the underlying cause of the seizures. Often, an easily reversible process will be uncovered, and the complete resolution of the seizure disorder can occur. In other circumstances, determining the cause of the seizure may allow early diagnosis and treatment of brain lesions or may disclose neurotoxicity, thereby modifying future treatment. This article reviews the causes, diagnostic evaluation, and treatment of seizures in adult patients with cancer, providing an overview of the medical and nursing aspects of patient management.

Decision Trees↗