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Biomedical subjects

A Langer

Publications and source records attributed to A Langer.

At least 19 recordsLinked to original sources
PubMed1992

Pathophysiology and prognostic significance of Holter-detected ST segment depression after myocardial infarction. The Tissue Plasminogen Activator: Toronto (TPAT) Study Group.

OBJECTIVES: We performed Holter monitoring on days 4 and 7 after acute myocardial infarction in 109 patients to assess whether ST segment shift would identify those with more severe coronary artery disease, left ventricular dysfunction and unfavorable prognosis. BACKGROUND: Silent myocardial ischemia is a frequent and prognostically significant event after acute myocardial infarction. However, the specific pathophysiologic mechanisms and the impact of thrombolytic therapy are uncertain. METHODS: In addition to Holter monitoring, patients underwent exercise testing, radionuclide angiography on days 1 and 9 and quantitative coronary angiography on day 9. RESULTS: Thirty-five patients (32%) had ST segment depression and had similar recombinant tissue-type plasminogen activator (rt-PA) treatment assignment and a reduced cross-sectional area of the infarct-related artery (0.59 +/- 0.57 vs. 1.04 +/- 1.26 mm2, p < 0.05). Global left ventricular function improved from day 1 to day 9 in patients without (4% +/- 11%, p < 0.001) but not in those with (0% +/- 7%) ST segment depression. In-hospital event rates were similar; however, follow-up 18 +/- 11 months after hospital discharge revealed a greater frequency of death and recurrent myocardial infarction in patients with compared with those without ST segment depression (27% vs. 6%, p = 0.03). CONCLUSIONS: After acute myocardial infarction, approximately one third of patients have ST segment depression on Holter monitoring, independent of the use of thrombolytic therapy. The unfavorable prognosis observed in these patients may be related to greater lumen obstruction in the infarct-related artery and lack of improvement in left ventricular function.

Cardiac Catheterization↗
PubMed1992

A randomized trial of psychosocial support during high-risk pregnancies. The Latin American Network for Perinatal and Reproductive Research.

BACKGROUND: It is often suggested that psychological and social support and health education for women at high risk for delivering a low-birth-weight infant can improve the outcomes of pregnancy, but the evidence is inconclusive. We undertook this prospective trial to evaluate a program of home visits designed to provide psychosocial support during pregnancy. METHODS: At four centers in Latin America, 2235 women at higher-than-average risk for delivering a low-birth-weight infant were recruited before the 20th week of pregnancy. The women were randomly assigned either to an intervention group (n = 1115) that received four to six home visits from a nurse or social worker in addition to routine prenatal care or to a control group (n = 1120) that received only routine prenatal care (with a mean of eight prenatal visits). The principal measures of outcome were low birth weight (< 2500 g), preterm delivery (< 37 weeks of gestation), and specified categories of maternal and neonatal morbidity. RESULTS: The women who received the home visits as well as routine prenatal care had outcomes that differed little from those of the women who received only routine care. The risks of low birth weight (odds ratio for the intervention group as compared with the control group, 0.93; 95 percent confidence interval, 0.68 to 1.28), preterm delivery (odds ratio, 0.88; 95 percent confidence interval, 0.67 to 1.16), and intrauterine growth retardation (odds ratio, 1.08; 95 percent confidence interval, 0.83 to 1.40) were similar in the two groups. There was no evidence that the intervention had any significant effect on the type of delivery, the length of hospital stay, perinatal mortality, or neonatal morbidity in the first 40 days. There was no protective effect of the psychosocial-support program even among the mothers at highest risk. CONCLUSIONS: Interventions designed to provide psychosocial support and health education during high-risk pregnancies are unlikely to improve maternal health or to reduce the incidence of low birth weight among infants.

Adolescent↗
PubMed1992

Aggressive clinical pattern of angina at restenosis following coronary angioplasty in unstable angina.

The frequency, clinical pattern, and timing of recurrent angina following successful single-lesion percutaneous transluminal coronary angioplasty (PTCA) was assessed in a consecutive group of 104 patients with stable angina and in 85 with unstable angina. In addition, the relationship between lesion morphology and angiographic features and the pattern of recurrent angina was determined. Restenosis, defined as recurrence of symptoms with > 50% stenosis at the site of PTCA, occurred in 25 (24%) of the stable group and in 23 (27%) of the unstable group (p = NS). The pattern of angina at repeat presentation was aggressive in nature in 8% of the stable group and in 48% of the unstable group (p = 0.002). The time interval between the recurrence of symptoms and repeat coronary angiogram or PTCA was longer in the nonaggressive group than in the aggressive group, 16 +/- 12.1 and 5 +/- 6.8 weeks, respectively (p < 0.003). The key factors predicting the recurrent angina pattern identified by multiple logistic regression analysis were the angina status pre-PTCA (p = 0.001) and the presence of double-vessel disease (p = 0.01). An aggressive pattern of angina at the time of restenosis is frequent in patients with unstable angina at the time of PTCA, and close post-PTCA surveillance is necessary in these patients.

Aged↗
PubMed1992

Thrombolysis in unstable angina. Randomized double-blind trial of t-PA and placebo.

BACKGROUND: Because coronary thrombosis is important in the pathogenesis of unstable angina and correlates with in-hospital cardiac events, we hypothesized that thrombolytic therapy would decrease cardiac events. METHODS AND RESULTS: We randomized 70 patients with unstable angina to tissue-type plasminogen activator (t-PA) (0.49 MU/kg for 1 hour followed by 0.07 MU/kg per hour for 9 hours) or placebo. All patients received full doses of intravenous heparin for 96 hours and aspirin (325 mg beginning at 72 hours). The primary end points of the study were in-hospital death, myocardial infarction, and urgent revascularization. Three secondary end points were also evaluated. Myocardial perfusion was assessed with resting planar thallium scintigraphy 90 minutes after initiation of therapy. Silent ischemia was assessed with 48-hour Holter monitoring for ST shift beginning at time of initiation of drug therapy. Coronary angiography was performed at 18 +/- 6 hours and analyzed quantitatively to assess the stenosis responsible for unstable angina, the presence of intraluminal filling defects consistent with intracoronary thrombus, and stenosis morphology and severity. There was no difference in total in-hospital cardiac events between patients receiving t-PA (5% or 14%) and those receiving placebo (7% or 20%) (p = 0.83). Resting thallium defects were larger in the patients receiving t-PA than in those receiving placebo (130 +/- 118 versus 76 +/- 84 degrees, p less than 0.04), and this difference persisted when corrected for previous infarction. Although the numbers of patients with ST shift were similar, the duration of ST shift was significantly longer in the patients receiving t-PA than with placebo (20 +/- 46 versus 3 +/- 10 minutes, p less than 0.045). The frequency of intracoronary thrombi in patients with stenoses greater than 50% was significantly less in patients treated with t-PA (11 of 22, 52%) as compared with placebo (23 of 25, 92%) (p = 0.002), but there was no significant difference in minimal lesion cross-sectional area (0.49 +/- 0.42 versus 0.57 +/- 1.08 cm2, p = 0.75) or ulceration index (0.79 +/- 0.16 versus 0.77 +/- 0.15, p = 0.71) of the culprit artery. CONCLUSIONS: We conclude that a prolonged infusion of t-PA in unstable angina reduces intracoronary thrombi but does not significantly decrease in-hospital cardiac events. The sample size, however, does not provide sufficient power to rule out a treatment effect. Paradoxically, there appears to be an increase in ST shift and worsening of myocardial perfusion with t-PA compared with therapy with heparin alone.

Aged↗
PubMed1992

Acute reduction of lipoprotein(a) by tissue-type plasminogen activator.

BACKGROUND: Lipoprotein(a) [Lp(a)] is a low density lipoprotein-like particle whose apolipoprotein B (apo B) moiety is disulfide-linked to apo(a), a plasminogen-like inhibitor of fibrinolysis in vitro. We hypothesized that plasma concentrations of Lp(a) are acutely affected by intravenous tissue-type plasminogen activator (t-PA). METHODS AND RESULTS: Patients with unstable angina were randomized to receive either intravenous t-PA (n = 15) or placebo (n = 11). Two-way ANOVA using repeated measures revealed a significant effect of t-PA on concentrations of Lp(a) (p = 0.026). There was a 48% fall in Lp(a) from baseline concentrations in the t-PA group at 12 hours (p = 0.031) but not at 72 hours. Lp(a) in the placebo group was unchanged. CONCLUSIONS: We conclude that t-PA produces a sharp and substantial but reversible reduction in plasma Lp(a). These data suggest that Lp(a) concentration is not as static in vivo as had been believed and might be acutely modifiable through some mechanism that induces its removal from the freely circulating state.

Angina, Unstable↗
PubMed1992

Reverse redistribution on exercise thallium scintigraphy: relationship to coronary patency and ventricular function after myocardial infarction.

OBJECTIVE: To define prevalence, pathophysiology and relation to thrombolytic therapy of reverse redistribution (appearance of a new, or worsening of an existing, scintigraphic defect on 4 h delayed images compared with the stress thallium image). DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Referral centre. PATIENTS: Sixty-three patients with acute myocardial infarction. INTERVENTIONS: Tomographic exercise thallium scintigraphy, radionuclide angiography, and quantitative coronary angiography. MAIN RESULTS: Tomographic exercise thallium scintigraphy performed at day 10 revealed fixed defects in 15 patients, reversible defects in 22 patients and reverse redistribution in 26 patients; no difference in treatment assignment (tissue plasminogen activator versus placebo) was found among the three groups. Left ventricular function was similar in patients with fixed or reversible defects and reverse redistribution; global ejection fraction was 48 +/- 14, 51 +/- 10 and 48 +/- 5%, respectively, and regional infarct ejection fraction was 36 +/- 15, 40 +/- 13 and 37 +/- 18%, respectively. However, nitroglycerin administration resulted in a significantly greater improvement in regional ejection fraction in reverse redistribution patients (5 +/- 4%) than that in patients with fixed defect (2 +/- 5%, P < 0.05) or reversible defects (3 +/- 5%, P < 0.05). The infarct-related artery had a greater cross-sectional area in reverse redistribution patients (1.5 +/- 1.42 mm2) compared with those with reversible defects (0.50 +/- 0.26 mm2, P < 0.05), but was similar to fixed defect patients (1.04 +/- 0.88). CONCLUSIONS: Reverse redistribution on tomographic thallium scintigraphy is a frequent phenomenon (occurring in 40% of patients following acute myocardial infarction) and is independent of thrombolytic therapy. Patients with reverse redistribution have a more widely patent infarct-related artery and similar ventricular function, but significantly greater functional improvement following nitroglycerin administration compared with those with reversible or fixed defects. These data suggest myocardial salvage within the infarct zone in some patients with reverse redistribution.

Animals↗
PubMed1991

Detection of silent myocardial ischemia in diabetes mellitus.

The prevalence of silent myocardial ischemia and its relation to autonomic dysfunction and pain threshold was studied in 58 men with diabetes mellitus and without cardiac symptoms. All patients underwent 48-hour ambulatory electrocardiographic monitoring and exercise testing after assessment of their autonomic function and pain threshold. Silent myocardial ischemia, defined as greater than or equal to 1 mm of ST-segment depression on either exercise testing or ambulatory electrocardiographic monitoring, was corroborated by exercise-induced reversible defect(s) on tomographic thallium scintigraphy. Autonomic function was assessed by heart rate response to: (1) Valsalva maneuver, (2) deep breathing, and (3) upright posture, as well as by diastolic blood pressure response to sustained handgrip and systolic blood pressure response to upright posture. Autonomic dysfunction was defined as greater than or equal to 2 abnormal responses. Pain threshold measurements were performed using electrical cutaneous stimulation of both forearms. Of the 58 diabetic patients, 21 were found to have autonomic dysfunction (36%). Silent myocardial ischemia was detected in 10 patients (17%), and was significantly more frequent in patients with than without autonomic dysfunction (38 vs 5%, p = 0.003). There was no difference in the electrical pain threshold or tolerance in subjects with and without silent myocardial ischemia. It is concluded that silent myocardial ischemia in asymptomatic diabetic men occurs frequently and in association with autonomic dysfunction, suggesting that diabetic neuropathy may be implicated in the mechanism of silent myocardial ischemia.

Adult↗
PubMed1991

Report of the Canadian Cardiovascular Society's consensus conference on the Management of the Postmyocardial Infarction Patient.

In October 1989, the Canadian Cardiovascular Society announced a program to achieve consensus on important issues in the care of patients with cardiovascular disease. This report on the management of the postmyocardial infarction patient represents the first in a series of these consensus conferences. The process for establishing consensus recommendations involved several steps. A primary panel of 11 experts from various fields was selected to review the available clinical evidence and to make a list of recommendations about management decisions in the postmyocardial infarction period. The initial report was distributed to a secondary panel of 16 reviewers* representing allied health care constituencies from across Canada. On the basis of the critical reviews and feedback from these reviewers, a revised report was distributed to all members (over 800) of the Canadian Cardiovascular Society for further review and feedback. This iterative approach resulted in a penultimate report that was presented at a plenary session of the annual scientific meeting of the Canadian Cardiovascular Society on Oct. 18, 1990, in Halifax, NS. On the basis of discussion and feedback from this symposium, the consensus review was completed.

Canada↗
PubMed1991

Root-retained overdentures: Part I--Biomechanical and clinical aspects.

Despite recent developments in dental implantology, the conservative approach to root preservation is still valid. In view of increased root caries rate in the elderly and lax oral hygiene habits of most overdenture wearers, placing protective copings on root abutments, when economically feasible, is the preferred method of treatment. Retention of overdentures is increased by including stud attachments in the abutments. Incorporation of cast metal frameworks is recommended to prevent base fractures.

Biomechanical Phenomena↗
PubMed1991

Relation between height and the maximum conduction velocity of the ulnar motor nerve in human subjects.

The maximum motor nerve conduction velocity of the right and left ulnar motor nerve was measured in more than 650 healthy medical students of both sexes. There was no side difference in the maximum conduction velocity. The shorter person has a statistically significant higher conduction velocity than the taller person. Comparison of students of both sexes showed a slightly higher conduction velocity in females. However, with regard to its relation to height, the conduction velocity was higher in males.

Adult↗
PubMed1991

Effect of sex hormones on human T cell activation by concanavalin A.

The effect of sex hormones on concanavalin A (Con A)-activated human T cells was studied. We show that neither 17 beta-estradiol (E2) nor progesterone, in concentrations of up to 10(-6) M, alters the proliferative response of peripheral-blood mononuclear cells (PBMC) of healthy postmenopausal women. Furthermore, the hormones had no effect on the composition of T cell populations and on the expression of activation markers. We extended our study to a unique T cell population that is characterized by the ability to form rosettes with human erythrocytes, following Con A activation (designated autorosette-forming cells; ARFC) and known to manifest suppressive activity. Indeed, the in vitro addition of E2 (neither progesterone nor testosterone) to Con A-stimulated PBMC brought an about 2- to 4-fold increase in the frequency of ARFC. Tamoxifen, an antiestrogen drug, reduced the frequency of estrogen-stimulated ARFC to the original low level. Furthermore, the inhibitory effect of growth medium from ARFC cultures originally stimulated with Con A + E2 was found to be higher than that of ARFC cultures originally stimulated with Con A alone.

Concanavalin A↗
PubMed1990

Prognosis in medically stabilized unstable angina: early Holter ST-segment monitoring compared with predischarge exercise thallium tomography.

OBJECTIVE: To assess the relative value of invasive and noninvasive predictors of outcome in patients after unstable angina. DESIGN: Cohort of 54 patients with unstable angina who had 6-month follow-up after stabilization on medical therapy. SETTING: University-based hospital, tertiary referral center. PATIENTS: Consecutive patients with unstable angina whose symptoms resolved while receiving medical therapy. MEASUREMENTS AND MAIN RESULTS: We prospectively compared 24-hour Holter ST-segment monitoring at admission, quantitative exercise thallium tomography, and cardiac catheterization 5 +/- 2 days after admission and analyzed their value for predicting a cardiac event in patients with unstable angina within 6 months. When patients with a favorable outcome (n = 40) were compared with patients with an unfavorable outcome (n = 11) no statistical difference was found in duration of ST shift of 1 mm or more on Holter monitoring (51 +/- 119 min compared with 37 +/- 43 min), exercise duration by the standard Bruce protocol (8.0 +/- 3.6 min compared with 7.9 +/- 3.1 min), exercise-induced ST depression (0.6 +/- 0.9 mm compared with 1.0 +/- 1.0 mm), and contrast left ventricular ejection fraction (70% +/- 10% compared with 69% +/- 15%). Patients with a favorable outcome were distinguished from those with an unfavorable outcome by a higher maximum rate-pressure product (24 x 10(3) +/- 6 x 10(3) compared with 18 x 10(3) +/- 7 x 10(3), P = 0.0025), smaller size of the reversible scintigraphic perfusion defect expressed as a percentage of total myocardium imaged (6% +/- 11% compared with 17% +/- 18%, P = 0.05) and a smaller number of vessels with stenosis of 50% or more (1.1 +/- 1.2 compared with 2.1 +/- 1.0, P = 0.01). On multiple logistic regression analysis, a history of previous myocardial infarction was the most powerful predictor of outcome. In patients without myocardial infarction, reversible exercise thallium perfusion defect size was the only predictor. CONCLUSION: After stabilization of an episode of unstable angina, quantitative tomographic exercise thallium scintigraphy has greater value for risk stratification than Holter ST-segment monitoring, particularly in patients who have not had a previous infarction.

Adult↗