Biomedical subjects

B J McAuley

Publications and source records attributed to B J McAuley.

11 recordsLinked to original sources

PubMed2000

An unusual samarium diiodide mediated reductive ring contraction of a tricyclic oxazine to a highly-functionalized cyclopentane and cyclobutane.

[reaction--see text] Samarium diiodide mediated reductive ring contraction of a substituted tricyclo[2.2.2]oxazine at 25 degrees C leads to a mixture of cyclopentane and cyclobutane rearrangement products with complete diastereoselectivity in each case. At -78 degrees C, the anticipated amidocyclohexanol reduction product is obtained exclusively, while the cyclopentane is the sole product at reflux in THF.

Cyclobutanes↗

PubMed1993

Directional coronary atherectomy complications and management.

Directional coronary atherectomy provides a predictable outcome in selected cases; however, DCA may still result in significant complications in a small number of patients. Although many of the complications are similar to those associated with PTCA, some of the complications are unique or more frequently observed with DCA. These complications are often preventable with adequate case selection and appropriate technique. Because of significant differences in the atherectomy procedure compared to PTCA, the operator should recognize and understand the technical differences to prevent potentially serious complications.

Atherectomy, Coronary↗

PubMed1992

Restenosis after directional coronary atherectomy.

OBJECTIVES: This study evaluates the incidence of restenosis after successful directional coronary atherectomy and identifies risk factors for restenosis. BACKGROUND: Directional coronary atherectomy has been shown to be a safe and effective treatment of obstructive coronary artery disease; however, information regarding restenosis is limited. METHODS: Between October 1986 and December 1989, 289 patients with 332 lesions were successfully treated with directional coronary atherectomy and followed up prospectively. Clinical follow-up information was available for 98% and angiographic follow-up information was obtained for 82% at approximately 6 months, or earlier if symptoms recurred. Angiograms were quantitatively analyzed. Restenosis was defined as greater than 50% stenosis at the site of intervention. RESULTS: Seventy-four percent of patients were either asymptomatic or clinically improved after the procedure. Thirty-two percent were subsequently treated by coronary artery bypass surgery (14%), percutaneous transluminal coronary angioplasty (4%) or repeat atherectomy (13%). Angiographic evidence of restenosis was observed in 42%. The restenosis rate in native coronary arteries was 31% for primary lesions and 28% and 49%, respectively, for lesions treated with one or two previous angioplasty procedures. The restenosis rate for saphenous vein grafts was 53% for primary lesions and 58% and 82%, respectively, for lesions treated with one or two previous angioplasty procedures. The median interval to angiographically documented restenosis was 133 days. A higher restenosis rate was associated with a saphenous vein graft, hypertension, a longer lesion (greater than or equal to 10 mm), a smaller vessel diameter (less than 3 mm), a noncalcified lesion and use of a smaller (6F) device. CONCLUSIONS: Restenosis remains a limitation of directional coronary atherectomy. A subset of patients with larger vessels, shorter lesions or lesions treated with a larger (7F) device may have a more favorable outcome.

Aged↗

PubMed1986

Angioplasty at coronary bifurcations: single-guide, two-wire technique.

A technique is described for angioplasty at coronary bifurcations. This simple approach utilizes a single guiding catheter, an exchange wire, and a conventional dilatation catheter and guidewire. With this "protective" guidewire technique, side branches at risk from occlusion during dilatation of a primary coronary segment can be protected and dilated secondarily; continual access to the threatened side branch is maintained with a "standby" exchange wire in the branch vessel.

Angioplasty, Balloon↗

PubMed1985

Efficacy of diltiazem for medically refractory stable angina: long-term follow-up.

To assess the efficacy of long-term diltiazem therapy when added to beta blockers and nitrates, we prospectively studied patients with chronic exertional angina who were determined to have medically refractory angina pectoris which was too severe to enter placebo-controlled studies. The mean follow-up time was 24.6 months (8-47 months) and all patients were seen every 2-4 months. Angina frequency decreased from a prediltiazem frequency of 9.5 episodes per week (1-40 per week) to 3.3 attacks per week (0-21 per week) at 6 months and 3.3 attacks per week (0-40 per week) at the patients's last evaluation. Similar reductions in nitroglycerin consumption were reported. Five patients had an increase in angina frequency during the mean 24.6 months of follow-up, which necessitated coronary bypass surgery, 8, 10, 12, 19, and 23 months after study entry, respectively. Diltiazem daily dosage ranged from 120 to 480 mg/day, the mean daily dose was 298 mg/day. Twenty (65%) patients remained on beta-blocker therapy and 19 (61%) patients on nitrate therapy in an effort to achieve a completely pain-free state. New cardiovascular events were documented in 3 patients during the follow-up period, with one patient having an uncomplicated myocardial infarction at 6 months, one patient hospitalized for prolonged chest pain at 2 months, and one patient dying following cardioversion for unrelated atrial fibrillation at 14 months poststudy entry. Adverse effects were reported during 19 of the 354 patient visits, but no patient had to stop therapy because of these. Sinus bradycardia required reduction of beta-blocker dosage in three patients and prolonged PR interval was observed in two additional patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1985

Angioplasty in total coronary artery occlusion: experience in 76 consecutive patients.

The influence of multiple clinical, angiographic and technical variables on the outcome of percutaneous transluminal coronary angioplasty was evaluated in a group of 76 consecutive patients with total coronary artery occlusion. Angioplasty was performed successfully in 53% of these patients. The likelihood of successful angioplasty was favorably influenced by: 1) a history of prior myocardial infarction in the distribution of the occluded arterial segment (p = 0.03); 2) an estimated maximal duration of arterial occlusion of less than 20 weeks (p less than 0.001); and 3) a length of nonvisualized arterial segment distal to the point of occlusion of less than 1.5 cm (p = 0.03). The outcome of coronary angioplasty was not significantly influenced by the vessel involved, the location of the occlusion within an involved vessel, the morphology of the occlusion (tapered versus abrupt) or the age and sex of the patient. There were no deaths and no vascular perforations. Four patients had recurrent coronary occlusion within 24 hours of the procedure; in three of these, recurrent occlusion was successfully treated with reangioplasty and in one, emergent surgical revascularization was performed. Embolic occlusion of an arterial branch distal to the point of total coronary occlusion occurred in 4 of the 40 successfully recanalized arteries. Seventy-five percent of patients having successful recanalization of an occluded coronary artery were free of the anginal symptoms that had prompted performance of the procedure at a mean follow-up period of 7.3 months. Thus, angioplasty of a total coronary artery occlusion can be performed safely and effectively, particularly in patients with a history of prior myocardial infarction, a brief estimated duration of coronary occlusion and a short nonvisualized occluded arterial segment.

Adult↗

PubMed1984

Advances in guidewire technology.

Since the introduction in 1979 of a movable guidewire system for PTCA, significant advances have been made in guidewire technology that have improved primary success rates and reduced complications with the use of this system. Coronary stenoses in distal sites or in branch vessels with abrupt angulations can now routinely be reached and crossed with newer-generation guidewires . This report concentrates on the evolution of advances in guidewire technology and outlines changes in guidewire design that have allowed for improved efficacy and safety with the movable wire system. Appropriate cases are presented to illustrate the advantages of available guidewires .

Angioplasty, Balloon↗

PubMed1984

Tissue response selectivity of calcium antagonists is not due to heterogeneity of [3H]-nitrendipine binding sites.

[3H]-nitrendipine binding data and isolated tissue response for five calcium antagonists were evaluated in rabbit myocardium and aorta. The [3H]-nitrendipine binding site was qualitatively identical in myocardium and aorta, as the [3H]-nitrendipine KD, KIS for nicardipine and nifedipine and interactions with verapamil, D600 and diltiazem were not different in aortic and cardiac membranes prepared by similar means. In contrast, the inhibition of the Ca2+-induced contractile response in right ventricular myocardium and aortic ring segments indicated a greater than 10,000 fold selectivity of nicardipine for antagonism of vascular responses. This resulted in a different order of potency for calcium antagonist interaction with the [3H]-nitrendipine binding site in cardiac membranes (nicardipine greater than nifedipine greater than D600 greater than verapamil greater than diltiazem) as compared to antagonism of myocardial tissue response (D600 greater than verapamil greater than or equal to nifedipine greater than nicardipine greater than or equal to diltiazem). In heart the difference between the potency of nicardipine in binding experiments and tissue response approached 4 orders of magnitude. We conclude that tissue response selectivity of calcium antagonists is not explained by heterogeneity of [3H]-nitrendipine binding sites.

Animals↗

PubMed1983

Prevention of cardiovascular events in variant angina by long-term diltiazem therapy.

In 43 patients with variant angina, the cardiovascular event rate during diltiazem therapy was compared with that in an equal time period before initiation of therapy. Cardiovascular events, that is, myocardial infarction, sudden death and hospitalization for prolonged angina, were decreased significantly (p less than 0.01) during the initial 6 months and mean 19.6 months of therapy. Based on the binomial principle, there were 22 events during the mean 19.6 months before therapy and 2 events during the equal time period on therapy. No patient died during follow-up. The frequency of angina was decreased by 94%. Diltiazem was well tolerated by all patients and no patient had to discontinue therapy because of adverse effects. It is concluded that long-term diltiazem therapy reduces cardiovascular events in patients with variant angina.

Adult↗

PubMed1983

Augmentation ventriculoplasty for treatment of hypertrophic cardiomyopathy.

Augmentation ventriculoplasty has the theoretical potential of partially altering abnormal diastolic properties by enlarging the left ventricular cavity and increasing the end-diastolic volume. This procedure was employed in a 26-year-old woman with symptomatic hypertrophic cardiomyopathy. Postoperatively, she had increased cardiac output and an improvement in clinical symptoms. We conclude that this procedure may be useful in patients with hypertrophic cardiomyopathy who have not responded to traditional medical and surgical therapy.

Adult↗

PubMedDate not supplied

The use of diltiazem hydrochloride in cardiovascular disorders.

Diltiazem, a calcium channel blocking agent, has potent cardiovascular effects that are directly related to its influence on vascular smooth muscle, ventricular myocardium, and specialized conducting tissue. It causes coronary and peripheral vasodilation, has a negative chronotropic and dromotropic effect, and little to no negative inotropic effect in patients with normal ventricular function. Diltiazem has potential use in a wide variety of cardiovascular disorders. It has been shown extremely effective in relieving the coronary artery spasm associated with variant angina. When compared with nitrates in patients with exertional angina, diltiazem has similar efficacy. Preliminary work indicates it will have a therapeutic role in the treatment of unstable angina. Because of its ability to improve the balance between myocardial oxygen supply and demand and reduce cellular injury secondary to ischemia, it is likely that diltiazem will be of benefit in the treatment of acutely ischemic myocardium during cardiopulmonary bypass and possibly acute myocardial infarction. It has proven efficacy in treating re-entrant supraventricular tachycardia. Adverse effects are seen in less than 5% of patients, indicating that it is well tolerated.

Angina Pectoris↗