PubMed Health⌕ Search

Biomedical subjects

R Kehoe

Publications and source records attributed to R Kehoe.

At least 19 recordsLinked to original sources
PubMed2000

Prompt Optical Observations of Gamma-Ray Bursts.

The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs). A search for optical counterparts to six GRBs with localization errors of 1 deg2 or better produced no detections. The earliest limiting sensitivity is mROTSE>13.1 at 10.85 s (5 s exposure) after the gamma-ray rise, and the best limit is mROTSE>16.0 at 62 minutes (897 s exposure). These are the most stringent limits obtained for the GRB optical counterpart brightness in the first hour after the burst. Consideration of the gamma-ray fluence and peak flux for these bursts and for GRB 990123 indicates that there is not a strong positive correlation between optical flux and gamma-ray emission.

Journal Article↗
PubMed1997

Implantable cardioverter defibrillator utilization among device recipients presenting exclusively with syncope or near-syncope.

INTRODUCTION: Implantable cardioverter defibrillators (ICDs) are occasionally used in presumed high-risk patients with electrocardiographically undocumented syncope, although the incidence of ventricular tachyarrhythmias in this population is not well defined. METHODS AND RESULTS: We studied 33 consecutive patients receiving an ICD (67% nonthoracotomy and 70% tiered therapy) after electrophysiologic testing for unmonitored "syncope" (n = 29) or "near-syncope" (n = 4). Atherosclerotic heart disease was present in 24 (73%); mean left ventricular ejection fraction (LVEF) was 0.39 +/- 0.15; and sustained monomorphic ventricular tachycardia (SMVT) was inducible in 18 (55%). Over a median follow-up of 17 months (range 4 to 61), 12 patients (36%) received > or = 1 appropriate ICD discharge triggered by SMVT (cycle length 230 to 375 msec) in 10 and ventricular flutter or fibrillation in 2--without concomitant antiarrhythmic medication in 8 of 12 cases. Inducible SMVT and LVEF < or = 0.35 were statistically significant, independent predictors of an appropriate ICD discharge (P < 0.02 and P < 0.03, respectively). Estimated 1-year cumulative survival free of appropriate discharge was 34% versus 87%, respectively, in patients with versus without inducible SMVT (P < 0.02), and 18% versus 56%, respectively, in patients with LVEF < or = 0.35 versus LVEF > 0.35 (P < 0.03). CONCLUSION: In this highly select, multicenter population of ICD recipients with electrocardiographically undocumented syncope, a substantial incidence of appropriate device discharges was observed, particularly in patients with inducible SMVT and LVEF < or = 0.35. These findings support the notion that, in patients with LV dysfunction and inducible SMVT, ventricular tachyarrhythmias are likely to account for episodes of syncope or near-syncope.

Adult↗
PubMed1995

Multicenter trial of sotalol compared with procainamide in the suppression of inducible ventricular tachycardia: a double-blind, randomized parallel evaluation. Sotalol Multicenter Study Group.

Sotalol is the prototype class III agent that combines beta-blocking properties with the propensity to prolong the effective refractory period by lengthening the action potential duration. Its precise effect on the prevention of ventricular tachycardia-ventricular fibrillation (VTVF) compared to class I agents has not been evaluated in a blinded study. In a double-blind parallel-design multicenter study, the electrophysiologic and antiarrhythmic effects of intravenous and oral sotalol (n = 55) and procainamide (n = 55) were therefore compared in patients with VTVF inducible by programmed electric stimulation. Sotalol produced a greater effect on lengthening the ventricular effective refractory period (VERP). It prevented the inducibility of VTVF in 30% versus 20% for procainamide, but this was not significantly different. In an alternate therapy group (n = 41) of similar patients previously refractory to or intolerant of procainamide, intravenous sotalol prevented inducibility in 32%. The pooled overall sotalol efficacy rate was 31%. There was a significant relation between the increase in the VERP and the prevention of inducibility of VTVF (n = 56; p < 0.02). VERP of > or = 300 msec was critical for the prevention of VTVF inducibility. Thirteen sotalol and 6 procainamide responders from the randomized group and 30 from the nonrandomized groups completed 1 year of oral sotalol therapy follow-up. Life-table analysis of these patient in each group showed a trend in favor of sotalol; however, statistical analysis was not possible because of the small numbers of patients. Both sotalol and procainamide were well tolerated. In the randomized group there was one case of sudden death during treatment with sotalol and two cases of nonfatal torsades de pointes in the procainamide group and two in the sotalol group; in the nonrandomized alternate therapy group, there were 6 cases of nonfatal torsades de pointes. The data support the emerging role of sotalol in the control of symptomatic ventricular tachycardia and fibrillation.

Administration, Oral↗
PubMed1994

Comparing self-reported and physician-reported medical history.

The authors compared self-reported medical history and medication use in a cataract case-control study of 1,380 persons (1985-1989) in Boston, Massachusetts, with information from the participants' physicians. Under- and overreporting varied by condition and type of medication. A self-reported history of hypertension had the highest sensitivity (91%), and diabetes history had the highest specificity (97%). Among different medications investigated, self-reported antihypertensive medication use was the most sensitive (88%), while self-reported use of insulin was the most specific (99%). Differences between patient- and physician-reported frequencies were very small, except for arthritis (15%) and regular aspirin use (21%). Results suggest an accurate recall of medical and drug usage history in well-defined chronic conditions.

Aged↗
PubMed1989

A pilot project of glaucoma in Barbados.

The prevalence of open-angle glaucoma is believed to be very high among West Indian blacks. To begin investigating the prevalence and risk factors for glaucoma and other eye diseases in Barbados, WI, a pilot study was conducted. The pilot project identified a stratified, random national sample of 300 persons over 35 years of age who were invited to participate in an ophthalmic examination and an interview. Of those contacted 89% were eligible and 95% of these agreed to participate. The overall glaucoma prevalence in the participants was 6%; it was 13% among black and mixed persons over 54 years. Age related cataract, hypertension, and diabetes were frequent findings. Although the sample size of the pilot project is small, the results suggest a high prevalence of glaucoma in Barbados, a finding that merits further study.

Adult↗
PubMed1989

New approach to defibrillator insertion.

The automatic implantable cardioverter/defibrillator has become an integral part of the management of patients with life-threatening ventricular rhythm disturbances. The considerable size of the device (250 gm, 10.8 by 7.6 cm) results in protrusion from the abdominal wall, with an associated alteration in self-image in all patients. In thin patients, erosion through the skin can occur. We have devised an operation in which the generator is implanted in, and becomes part of, the chest wall. The two patients in whom this approach has been used are virtually unaware of the presence of the device. We propose this operation as an alternative to abdominal wall insertion when the latter is unsuitable for technical reasons.

Aged↗
PubMed1988

Factors determining programmed stimulation responses and long-term arrhythmic outcome in survivors of ventricular fibrillation with ischemic heart disease.

The clinical and angiographic features of 38 patients with ischemic heart disease and nonacute infarction pre-hospital ventricular fibrillation (VF) were examined as a function of their drug-free programmed electrical stimulation (PES) responses. Twenty-two patients (58%) had inducible ventricular tachycardia (VT) at drug-free PES (group I) and 16 patients (42%) did not (group II). Group I had more patients with: (1) remote infarction (22 of 22 vs 2 of 16; p less than 0.01; (2) history of congestive failure (16 of 22 vs 0 of 16; p less than 0.01); (3) prior cardiac arrest (11 of 22 vs 0 of 16; p less than 0.01); (4) left ventricular (LV) ejection fraction less than 40% (19 of 22 vs 1 of 16; p less than 0.01); and (5) akinetic or dyskinetic LV wall motion (22 of 22 vs 2 of 16; p less than 0.001). Group II had more patients with: (1) LV segments at "ischemic jeopardy" (16 of 16 vs 14 of 22; p less than 0.01) and (2) factors suggestive of ischemia at the onset of VF (13 of 16 vs 1 of 22; p less than 0.001). Inducible VT (IVT) was suppressed in 16 of the 20 group I patients surviving hospitalization while four were discharged with persistence of IVT despite therapy. At 27 +/- 15 months, all four with persistent IVT had a recurrence of their arrhythmia. In the 16 group II patients, therapy was limited to antiischemic measures: coronary bypass in 12, propranolol in 3, and angioplasty in one. At 38 +/- 9 months, no group II patient has had a recurrence of his arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

Low heart rate variability and sudden cardiac death.

Our results indicate the following. 1. HRV is markedly depressed in inducible SCD survivors, a group at high risk of a subsequent episode of SCD. 2. Studies on patients who developed SCD during Holter monitoring indicate that HRV is depressed prior to SCD. 3. HRV is markedly depressed in inducible "asymptomatic ventricular ectopy" patients, with the degree of reduction paralleling that observed in inducible SCD survivors. In contrast, HRV of noninducible "asymptomatic ventricular ectopy" patients did not differ statistically from normal. 4. The findings provide additional evidence that cardiac parasympathetic function is depressed in patients prone to development of SCD and that altered autonomic function contributes to the development of electrical instability in such individuals. This accords with findings that such risk factors for sudden death as coronary artery disease, myocardial infarction, congestive failure, and hypertension all have been associated with reduced parasympathetic activity or attenuation of parasympathetically mediated reflexes. It is tempting to believe that diminished cardiac parasympathetic activity, perhaps by failing to counter excess sympathetic activity, contributes to SCD. 5. It may be inferred that HRV measurements have potential for serving as an independent predictor of inducibility in response to programmed ventricular stimulation and that they could represent a noninvasive screen for patients referred for evaluation of risk of SCD because of asymptomatic ventricular ectopy or other causes. In a larger sense, the data suggest that HRV measurements may provide information pertinent to the identification of individuals at increased risk of SCD that is independent of that provided by other risk factors. Given the human and economic stakes, further study is clearly warranted.

Death, Sudden↗
PubMed1988

Amiodarone-induced pneumonitis. Assessment of risk factors and possible risk reduction.

Problems with pulmonary toxicity have emerged as a potentially limiting factor for amiodarone use. We prospectively studied 33 subjects treated with amiodarone for refractory arrhythmias. Serial clinical, radiographic and pulmonary function tests were correlated with the dose and duration of amiodarone treatment to define: a) prevalence of lung toxicity, b) subgroups of patients at particular risk for toxicity, c) potential interaction between amiodarone dose and toxicity. Considering all subjects, no significant change in lung volumes or airflow indices were noted; carbon monoxide diffusing capacity (DCO) underwent a mean reduction of 20.3 percent during treatment. Symptoms of possible pulmonary toxicity occurred in 27.3 percent of subjects. No type or degree of pretreatment cardiopulmonary dysfunction predicted lung toxicity. However, maintenance dose was correlated with toxicity; patients treated with doses of less than or equal to 400 mg per day from the start of treatment had insignificant reductions in DCO and did not develop symptoms.

Adolescent↗
PubMed1982

Aprindine-induced polymorphous ventricular tachycardia.

Five cases of aprindine-induced polymorphous ventricular tachycardia (torsade de pointes) are presented. In four cases, polymorphous ventricular tachycardia appeared after the oral administration of 400 mg of aprindine. One patient had mild hypokalemia at the time of polymorphous ventricular tachycardia so that a direct cause and effect relation between the drug and the tachycardia cannot be established. All five patients manifested Q-T prolongation and recurrent syncope due to polymorphous ventricular tachycardia. In all five, polymorphous ventricular tachycardia subsided once administration of aprindine was discontinued.

Aged↗
PubMed1981

Ventricular tachycardia: prediction of response to oral aprindine with intravenous aprindine.

Aprindine was administered both intravenously and orally to 25 patients with ventricular tachycardia refractory to conventional antiarrhythmic agents to test the hypothesis that the response to intravenous aprindine predicts the response to oral aprindine. Ten patients had incessant ventricular tachycardia and 15 had paroxysmal sustained inducible ventricular tachycardia. Eleven patients (43 percent) had conversion to sinus rhythm with intravenous aprindine (nine with incessant and two with paroxysmal sustained ventricular tachycardia). Thirteen patients (all with paroxysmal sustained ventricular tachycardia) manifested slowing of the tachycardia without conversion, whereas in one patient with incessant ventricular tachycardia, the tachycardia became less frequent and nonsustained after intravenous aprindine. All 11 patients who had conversion to sinus rhythm with intravenous aprindine remained free of ventricular tachycardia during oral treatment with aprindine (at 2 weeks) and for a follow-up period of 2 to 38 months (mean 16 +/- 13). Of the 14 patients who did not have conversion to sinus rhythm with intravenous aprindine, 12 had spontaneous or inducible ventricular tachycardia, or both, at evaluation 1 to 2 weeks after initiation of oral aprindine. In conclusion, administration of intravenous aprindine to patients with ventricular tachycardia is helpful in predicting the subsequent response to oral aprindine. In addition, the pattern of ventricular tachycardia predicted the response to aprindine; patients with incessant ventricular tachycardia tended to respond, and those with paroxysmal sustained ventricular tachycardia tended not to respond.

Administration, Oral↗
PubMed1979

Multiple reentrant tachycardias due to retrograde conduction of dual atrioventricular bundles with atrioventricular nodal-like properties.

A patient is presented who had two paroxysmal supraventricular tachycardias, one slow and incessant and the other fast. Both paroxysmal tachycardias appeared to be atrioventricular (A-V) reentrant, with anterograde conduction by way of a normal A-V pathway. Two pathways conducting in retrograde manner were demonstrated, characterized by different conduction times (fast and slow), identical abnormal atrial activation sequence and A-V nodal-like properties (retrograde Wenckebach periodicity with rapid ventricular pacing, and depression with ouabain and propranolol). Thus, there appeared to be two anomalous A-V bundles with nodal-like properties conducting in retrograde fashion. Whether the paroxysmal tachycardia was fast or slow depended on which of these pathways was utilized. Spontaneous cure of incessant paroxysmal tachycardia was observed and coincided with unexplained total loss of ability for ventriculoatrial conduction.

Atrioventricular Node↗
PubMed1979

Paroxysmal supraventricular tachycardia induction in patients with Wolff-Parkinson-White syndrome.

In 54 patients with pre-excitation, 30 (56%) had inducible A-V re-entrant paroxysmal tachycardia. Of these 30, 20 had spontaneous paroxysmal tachycardia (four also had atrial fibrillation), four had spontaneous paroxysmal atrial fibrillation, five had a history of palpitation without arrhythmia, and one was asymptomatic. In 24 patients (44%), paroxysmal tachycardia was not inducible. Of these 24, none had documented paroxysmal tachycardia, four had atrial fibrillation, none had palpitation without arrhythmia, and 11 were asymptomatic. The incidence of documented paroxysmal tachycardia was higher in the patients with inducible tachycardia (P less than 0.001). Tachycardia induction was noted in 20 of 20 patients with spontaneous paroxysmal tachycardia, eight of 12 patients with paroxysmal atrial fibrillation, five of 14 patients with palpitation and no arrhythmia, and one of 12 asymptomatic patients. The frequency of ability to induce paroxysmal tachycardia was significantly higher in both the patients with documented spontaneous paroxysmal tachycardia and the patients with paroxysmal atrial fibrillation than in the asymptomatic group (P less than 0.01).

Adolescent↗
PubMed1979

Chronic nonparoxysmal sinus tachycardia in otherwise healthy persons.

Seven patients had chronic, unexplained, nonparoxysmal sinus tachycardia. The clinical, electrocardiographic, and electrophysiologic characteristics of these cases are described. In each case electrocardiographic and electrophysiologic observations suggested that tachycardia was nonparoxysmal and due to increased automaticity of the sinus node (or of an automatic atrial focus located very near the sinus node). The mechanisms of increased sinus node automaticity in these patients were explored using drugs affecting the autonomic nervous system. In each patient these studies suggested a defect in either sympathetic or vagal nerve control of resting heart rate, with or without an abnormality of intrinsic heart rate. Data are also presented on baroreceptor reflex arc function in these patients.

Adolescent↗