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Biomedical subjects

B J Allen

Publications and source records attributed to B J Allen.

At least 127 records · Page 7Linked to original sources
PubMed1988

Failure of ambulatory electrocardiographic monitoring to predict results of programmed electrical stimulation. Studies in patients with clinical ventricular tachyarrhythmias.

To test for an association between the results of ambulatory electrocardiographic monitoring (AEM) and programmed electrical stimulation (PES), or whether other factors better predict the results of PES, 57 patients (36 male and 21 female patients) presenting with either ventricular fibrillation (49 percent; 28/57) or sustained ventricular tachycardia (51 percent; 29/57) were studied. Each patient underwent AEM and PES using up to three ventricular extrastimuli. Sixty-three percent (36/57) had coronary disease; and of these, ventricular tachycardia was present during AEM in 64 percent (23/36) and induced by PES in 78 percent (28/36). With the addition of patients with other cardiac diagnoses, the results were 58 percent (33/57) and 60 percent (34/57), respectively. No AEM variable was positively associated with inducible ventricular tachycardia, including frequency of ventricular premature depolarizations, multiformity, couplets, or ventricular tachycardia. Clinical variables positively associated with inducible ventricular tachycardia were coronary disease, previous myocardial infarction, left ventricular dysfunction, male sex, and a history of recurrent arrhythmia. Therefore, clinical characteristics are more useful for predicting the results of PES than information derived from AEM.

Cardiac Pacing, Artificial↗
PubMed1987

Amiodarone for maintenance of sinus rhythm after conversion of atrial fibrillation in the setting of a dilated left atrium.

Previous reports suggest that the finding of left atrial (LA) dilatation (greater than 45 mm) by echocardiography identifies patients not likely to maintain sinus rhythm after conversion of atrial fibrillation (AF). However, these studies antedate the availability of amiodarone, an antiarrhythmic agent that reportedly is effective in patients with AF in whom other drug therapy has failed. To analyze the relation between LA size and the ability to maintain sinus rhythm with amiodarone therapy, 28 patients, aged 32 to 87 years (mean 61), with an LA dimension greater than 45 mm (range 46 to 78, mean 57) were studied. Thirteen patients (46%) had valvular heart disease, 10 (36%) dilated cardiomyopathy and 5 (18%) miscellaneous disorders. In 25 patients (89%) quinidine therapy had failed. After therapy with amiodarone, sinus rhythm returned in all patients and was maintained. Therapy was judged completely successful in 10 patients (alive and still in sinus rhythm with at least 1 year of follow-up), partially successful in 11 (maintaining sinus rhythm for at least 6 months before a change in status) and failed in 7. Completely successful therapy was accomplished in 9 of 18 patients with an LA dimension between 46 and 60 mm, but in only 1 of 10 patients with an LA dimension greater than 60 mm (p less than 0.05). Thus, patients with LA dimensions between 46 and 60 mm who are significantly compromised by AF can often be maintained in sinus rhythm with amiodarone therapy. However, in patients with larger LA dimensions. AF is likely to return despite aggressive antiarrhythmic therapy with amiodarone, a drug with potentially serious side effects.

Adult↗
PubMed1987

Ventricular tachyarrhythmia associated with psychological stress. The role of the sympathetic nervous system.

Psychological stress has been reported to be a risk factor for sudden cardiac death in individuals both with and without underlying structural heart disease. From a group of 80 patients presenting with life-threatening ventricular tachyarrhythmia, six were identified without underlying structural heart disease. Five of these six patients experienced marked psychological stress. Each of these five patients underwent arrhythmia evaluation, demonstrating recurrent rapid monomorphic ventricular tachycardia related to changes in tone of the sympathetic nervous system. Subsequently, solitary beta-adrenergic blocker therapy was given to each patient. During therapy, four of the five patients had a marked reduction of both arrhythmia and symptoms during a follow-up ranging from 29 to 49 (mean, 38) months.

Adrenergic beta-Antagonists↗
PubMed1986

Enhanced survival in patients with heart failure and life-threatening ventricular tachyarrhythmias.

Previous reports have suggested that patients with heart failure and coexistent ventricular tachyarrhythmias have a 1-year mortality of 40% to 60%. To assess whether an antiarrhythmic management program could reduce mortality, we studied 20 consecutive patients with ventricular fibrillation (12) or ventricular tachycardia (eight) and heart failure. Coronary disease was the most common underlying cardiac disorder (85%). Heart failure was managed with digoxin (16), diuretics (16), and vasodilators (seven). All patients received antiarrhythmic drug therapy guided by both noninvasive and invasive studies. This included single (10) or combination drug therapy (10). Beta blockers were used alone or in combination for arrhythmia control in 11 patients. One-year survival was 89%. We conclude that an effective program can be developed for patients with life-threatening ventricular tachyarrhythmias and heart failure. Combination antiarrhythmic drug therapy is often required. Despite impaired left ventricular function, beta-blocking drugs can be used, and may be important.

Anti-Arrhythmia Agents↗
PubMed1986

Accumulation of chlorpromazine and thiouracil by human melanoma cells in culture.

The uptake (total radioactivity in intact cells) and incorporation (radioactivity bound to acid-precipitable material) of 14C-chlorpromazine (CPZ) and 14C-thiouracil (TU) were studied using a library of 3 human fibroblast strains and 13 tumour cell lines. In contrast to previous studies using rodent melanomas in vivo, the melanoma lines, including lines with high tyrosinase and melanin contents, did not take up more CPZ and TU than non-melanoma cells (fibroblasts, HeLa cells). Incorporation of CPZ was also broadly similar in all cell types studied. TU was selectively incorporated into the melanoma line having a high tyrosinase and melanin content but not into lines with high tyrosinase activity and low melanin content. While supporting the possibility of selective therapy for heavily-pigmented melanomas using labelled TU derivatives, these results suggest that the action of potentially melanoma-affined compounds should be further evaluated in human cells. Unlabelled CPZ or TU was not selectively toxic to melanoma cells. Unexpectedly, methylation-sensitive tumour cells (Mer-phenotype) were highly resistant to TU, thus providing a new experimental tool for understanding the genesis of this phenotype in vivo.

Cell Line↗
PubMed1986

Solitary beta-blocker therapy for idiopathic life-threatening ventricular tachyarrhythmias.

To determine the clinical characteristics of patients with life-threatening ventricular tachyarrhythmias with no identifiable heart disease, we analyzed six patients who presented with either cardiac arrest or syncope associated with documented ventricular tachycardia or fibrillation. Electrocardiographic and echocardiographic examination and cardiac catheterization results were normal in all patients. Electrocardiographic monitoring revealed ventricular tachycardia in all patients. Exercise testing did not provoke sustained ventricular tachycardia in any patient. Programmed extrastimulation did not induce ventricular tachycardia in any patient. Isoproterenol infusion facilitated provocation of sustained ventricular tachycardia in only one patient. All six patients were treated with solitary beta-blocker therapy. Following treatment, there was a significant reduction in the incidence of ventricular tachycardia, couplets and total ventricular ectopic beats. During a follow-up period ranging from 16 to 36 (mean 22) months, all patients remain alive without clinically significant recurrence. Therefore, patients with life-threatening ventricular tachyarrhythmias without identifiable heart disease may respond to solitary beta-blocker therapy.

Adrenergic beta-Antagonists↗
PubMed1985

Propafenone therapy for ventricular tachycardia in the setting of congestive heart failure.

The combined occurrence of impaired left ventricular function and ventricular tachyarrhythmias portend a high annual mortality. Although antiarrhythmic drugs can reduce ventricular arrhythmias, the prognosis may be unchanged. We administered propafenone to 12 patients with ventricular tachyarrhythmias and left ventricular ejection fractions less than 40%. Propafenone significantly reduced isolated ventricular premature depolarizations, couplets, and ventricular tachycardia on ambulatory monitoring. Propafenone eliminated all exercise provocable ventricular tachycardia. Propafenone additionally abolished ventricular tachycardia inducible by programmed stimulation in five of six patients. In eight patients studied before and during therapy, there was no significant change in left ventricular ejection fraction determined by nuclear ventriculography. Propafenone was discontinued in three patients due to side effects. All patients remain alive and without recurrence of clinically significant arrhythmia over a mean follow-up period of 14 months. Propafenone is an effective drug for the management of ventricular tachyarrhythmias, and may be used in patients with impaired left ventricular function.

Administration, Oral↗
PubMed1985

Propafenone.

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Anti-Arrhythmia Agents↗
PubMed1983

Neutron therapy.

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Brain Neoplasms↗
PubMed1977

Hypolipidemic arylthioalkanoic acids.

A series of arylthioalkanoic acids related to probucol was studied for hypolipidemic activity. Homologation of the alkyl side chain led to marked changes in the serum cholesterol and serum triglyceride lowering activity in rats with the best combination of properties appearing in compound 7, 2-[3,5-di-tert-butyl-4-hydroxyphenyl)thio]hexanoic acid. Modification of the ring substitution failed to improve the activity despite the empirical observation that lipophilic substitution was necessary. Removal of the phenolic hydroxyl produced compound 23 with properties similar to 7 but of somewhat lower activity. Replacement of the sulfur by oxygen increased the toxicity of the series. Resolution of racemic 7 did not change the activity of the compound. The LD50 in mice of 7 was between 5000 and 10 000 mg/kg and compound 7 has been submitted for human clinical evaluation.

Animals↗