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Biomedical subjects

A Langer

Publications and source records attributed to A Langer.

At least 73 records · Page 4Linked to original sources
PubMed1995

Treatment of silent ischemia in unstable angina: a randomized comparison of sustained-release verapamil versus metoprolol.

Silent ischemia is a frequent finding in patients with unstable angina and portends a poor prognosis. We compared the efficacy of sustained-release (SR) verapamil and metoprolol in reducing silent ischemia in patients with unstable angina and assessed whether detection of silent ischemia was related to unfavorable outcomes in the contemporary setting of concurrent therapy with heparin and aspirin. Holter monitoring (leads a VF, V2, V5) for the first 72 h was used to assess the frequency and duration of ST-shift episodes. There were 37 patients in the verapamil-SR group and 40 patients in the metoprolol group, with both groups having similar baseline characteristics. There were more episodes of angina in the verampamil-SR group (29 vs. 12, p = 0.05). There was no difference between the two groups in the frequency (51 vs. 49 episodes, p = 0.9) or duration (23 +/- 48 vs. 18 +/- 50 min, p = 0.6) of ST-shift episodes. There were 20 unfavorable in-hospital outcomes distributed equally between the two groups (p = 0.9). Patients with unfavorable outcomes had ST shift more often (50 vs. 28%, p = 0.07) and for a longer duration (40 +/- 69 vs. 13 +/- 38 min, p = 0.03). Patients with ST shift > or = 60 min had a 60% probability of unfavorable outcome compared with 33% for ST shift of 1-59 min duration and 20% for no ST shift (p = 0.04). We conclude that metoprolol appears to reduce symptoms better than verapamil-SR, but no difference in silent ischemia or unfavorable outcomes was seen. Silent ischemia remains a common occurrence in these patients despite heparin and aspirin therapy and its detection continues to have prognostic value.

Adrenergic beta-Antagonists↗
PubMed1995

Multicenter evaluation of the Strecker tantalum stent for acute coronary occlusion after angioplasty.

The Strecker stent is a balloon-expandable, flexible endoprosthesis constructed of knitted tantalum wire and has been implanted successfully in peripheral arteries. This study presents the first multicenter experience with implantation of this radiopaque device in the coronary arteries in 64 patients of 6591 consecutive percutaneous transluminal coronary balloon angioplasty (PTCA) procedures complicated by abrupt closure. In all except 1 patient the stents (n = 72) were correctly placed, and flow could be reestablished immediately. During hospitalization 12 (19%) patients had stent closures; 5 (8%) patients had Q-wave myocardial infarctions; and 13 (20%) patients underwent bypass surgery (4 on an emergency basis). The in-hospital mortality was 9%: 2 patients died after thrombotic stent occlusions; 2 patients had fatal bleeding complications; and 2 patients died after bypass surgery. Major bleeding complications at the puncture site were observed in 8 (12.5%) patients. Angiograms (n = 45) after 17 +/- 5 weeks revealed a stent patency rate of 89%. Thus the Strecker coronary stent proved to be helpful in the management of acute vessel closure during PTCA. However, in this first series a high incidence of early thrombotic occlusions and bleeding complications warrants close anticoagulation monitoring and limits broader indications.

Angioplasty, Balloon, Coronary↗
PubMed1995

Impact of health education during pregnancy on behavior and utilization of health resources. Latin American Network for Perinatal and Reproductive Research.

OBJECTIVE: Our purpose was to assess whether an intervention in the education of the mother and the support person involves a change in health-related behavior and use of health facilities. STUDY DESIGN: A randomized, controlled trial was conducted in four cities of Latin America on pregnant women at risk. Half of them (n = 1115) received a home intervention of four to six visits dealing with psychosocial support and education about health-related habits, alarm signs, hospital facilities, antismoking and antialcohol programs, and a reinforcement of adequate health services utilization for the pregnant woman and a support person. The control group (n = 1120) received routine prenatal care. RESULTS: The distribution of risk factors and demographic, obstetric, and psychologic characteristics at baseline was similar in both groups. Women in the intervention group showed a statistically significant better knowledge of seven of the nine alarm signs considered and of two of the three labor-onset signs required. No differences between groups were observed in improvement on diet, cigarette and alcohol consumption, maternal physical strain, lactation at 40 days postpartum, and utilization of health facilities. CONCLUSIONS: An intervention of psychosocial support and health education during pregnancy failed to show any benefit on perinatal outcome, health-related behavior, or utilization of health facilities.

Alcohol Drinking↗
PubMed1995

Noninvasive assessment of speed and stability of infarct-related artery reperfusion: results of the GUSTO ST segment monitoring study. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries.

OBJECTIVES: The ST segment monitoring substudy of the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) trial compared the speed and stability of ST segment recovery among four thrombolytic strategies for acute myocardial infarction. BACKGROUND: Rapid resolution of ST segment elevation has been suggested as a noninvasive marker of infarct-related artery patency. We expected that patients treated with accelerated recombinant tissue-type plasminogen activator (rt-PA) would show a quicker recovery than that of other patients but that those treated with streptokinase would show greater stability of recovery. METHODS: ST segment monitoring was initiated in 1,067 patients within 30 min of the start of thrombolysis and continued for > 18 h with the use of a three-channel continuous vectorcardiographic monitor, a 12-lead continuous electrocardiographic (ECG) monitor or a three-channel (V2, V5, aVF) Holter ambulatory ECG monitor. RESULTS: Time to 50% recovery could be assessed in 618 patients and was similar in the four treatment groups: median 45 min with streptokinase/subcutaneous heparin, 45 min with streptokinse/intravenous heparin, 42 min with accelerated rt-PA and 47 min with combination therapy (p = 0.7). No significant difference among the thrombolytic regimens was shown with the three monitors used. Time to initiation of ST segment analysis was directly related to time to 50% recovery (p = 0.0001) and was its best predictor in a multiple regression model. ST segment elevation recurred equally in each treatment group (approximately 36%, p = 0.9) but was significantly more common in patients with a patent infarct-related artery (p = 0.033) or a low ejection fraction (p = 0.001). CONCLUSIONS: The greater 90-min patency seen with accelerated rt-PA in the angiographic substudy did not correlate with a shorter time to 50% ST segment recovery, possibly because of technical limitations and study design. The similar rates of recurrent ischemia (as assessed by ST elevation) among the regimens support the similar infarction and reocclusion rates seen in the main trial and angiographic substudy.

Drug Therapy, Combination↗
PubMed1995

Association between QT dispersion and autonomic dysfunction in patients with diabetes mellitus.

OBJECTIVES: We hypothesized that QT dispersion would be increased in patients with diabetes mellitus and autonomic dysfunction and that QT dispersion would be related to abnormal iodine-123 (I-123) metaiodobenzylguanidine (MIBG) uptake. BACKGROUND: Patients with diabetes mellitus and autonomic dysfunction have an increased incidence of sudden death. This event may be due to a sympathetic imbalance causing disturbances of repolarization. QT dispersion has recently been demonstrated to reflect dispersion of ventricular refractoriness and is a marker of arrhythmogenic potential. Uptake of I-123 MIBG is a reliable measure of whether the tissue examined receives sympathetic neuronal innervation. METHODS: Fifty-one diabetic patients and 11 normal subjects were studied. All patients had clinical evaluation for autonomic dysfunction (defined as at least two abnormal heart rate and blood pressure responses to five validated tests). Rest 12-lead electrocardiograms were recorded for measurement of QT dispersion, defined as the longest QT interval minus the shortest QT interval, and corrected for heart rate using Bazett's formula. Visual and quantitative measurements of I-123 MIBG uptake were performed using I-123 MIBG, and technetium-99m sestamibi uptake was used to assess perfusion. RESULTS: Thirty-five diabetic patients had autonomic dysfunction. Corrected QT dispersion was significantly greater in the patients than in the normal subjects (p = 0.02). The I-123 MIBG scores were also significantly greater in patients with than without autonomic dysfunction (p = 0.0004) and in normal subjects (p = 0.008). There was no correlation between QT dispersion and I-123 MIBG uptake score (r = 0.006, p = 0.97). CONCLUSIONS: Diabetic patients with autonomic dysfunction have increased QT dispersion and larger I-123 MIBG uptake defects. This finding suggests that such patients have a greater inhomogeneity of repolarization. The lack of correlation between QT dispersion and I-123 MIBG uptake suggests that these abnormalities are mediated by different mechanisms.

3-Iodobenzylguanidine↗
PubMed1995

Pathophysiology and time course of silent myocardial ischaemia during mental stress: clinical, anatomical, and physiological correlates.

OBJECTIVE: To define the prevalence and pathophysiology of myocardial ischaemia induced by mental stress in patients with coronary artery disease and exercise inducible ischaemia, and to determine the correlation between the severity of coronary artery disease and ischaemia induced by speech. DESIGN: Prospective cohort study. SETTING: Tertiary care academic institution. PATIENTS AND PROTOCOL: 47 patients with coronary artery disease and 20 normal controls were studied using standardised exercise and mental stress. The ambulatory nuclear vest provided continuous measures of left ventricular ejection fraction and relative volume changes: an ischaemic response to mental stress was defined as a decrease in ejection fraction of > or = 5% for > or = 60 s. Severity of coronary artery disease was assessed by the extent of thallium reversibility on exercise testing and the severity of angiographic disease. RESULTS: 23 (49%) of 47 patients with coronary artery disease had an ischaemic response to mental stress which occurred early, was sustained throughout the task and associated with an increase in end systolic volume. In contrast, the pattern of left ventricular response in the remaining 24 patients (51%) resembled that in the normal controls. Patients with mental stress induced ischaemia tended to have greater severity of coronary disease (mean (SD) total number of diseased vessels 1.9 (0.8) v 1.4 (0.9), P = 0.07), more frequent exercise induced angina (17/23 v 7/24, P = 0.003) and lower increases in heart rate (36 (11) v 49 (23) beats per min, P = 0.023) and systolic blood pressure (32 (19) v 45 (18) mm Hg, P = 0.03) during exercise. Left ventricular responses to speech and exercise were compared in the 23 patients with mental stress induced ischaemia: mental stress was associated with a greater decrease in ejection fraction at comparable increases in rate pressure product (-6.5 (6.3)% v 4.7 (11.2)%, P = 0.0001). CONCLUSIONS: These findings suggest that mental stress induction of myocardial ischaemia is common in patients with stable coronary artery disease. Susceptible patients may have more functionally severe coronary disease. The time course, pattern, and haemodynamic features of mental stress induced ischaemia suggest a dynamic decrease in coronary supply.

Adult↗
PubMed1995

Current status of silent myocardial ischemia.

A significant proportion of myocardial ischemia is 'silent' in nature. Furthermore, this asymptomatic ischemia portends an adverse prognosis for patients with known coronary artery disease. Silent myocardial ischemia can be objectively assessed and quantified by a number of noninvasive means; however, ambulatory electrocardiographic monitoring has emerged as a preferred method for both detection and analysis in hospital and during daily life conditions. Silent myocardial ischemia exhibits a circadian pattern. It represents an imbalance between myocardial oxygen supply and myocardial oxygen demand, and can be triggered by both physical and mental stress. The important role of endothelial dysfunction and autonomic nervous system influences has been recently elucidated. Up to 75% of ischemic episodes in patients are silent. Patients with asymptomatic coronary artery disease, chronic stable angina and unstable angina, and those postmyocardial infarction or postrevascularization who exhibit ST segment shift all show adverse short and long term prognosis compared with controls. Treatment modalities have included nitrates, beta-blockers, calcium antagonists, phosphodiesterase inhibitors, anxiolytics, anti-platelet agents and revascularization procedures. While the majority of these studies have demonstrated significant reduction in the frequency of silent myocardial ischemia, limited data on influencing prognosis are available; thus recommendations regarding treatment of these patients await the results of ongoing clinical trials.

Adrenergic beta-Antagonists↗
PubMed1995

Detection of silent ischemia adds to the prognostic value of coronary anatomy and left ventricular function in predicting outcome in unstable angina patients.

BACKGROUND: Patients with unstable angina are at increased risk of unfavourable outcomes such as myocardial infarction, death and urgent revascularization. Early risk stratification may improve subsequent outcome. Recently the presence and duration (at least 60 mins) of silent ischemia as measured by Holter monitoring has been shown to be of prognostic value. The incremental value of this information over that provided by coronary angiography and assessment of left ventricular function is not known. OBJECTIVE: To determine whether detection of silent ischemia is of independent and additional prognostic significance beyond that provided by the angiographic extent of coronary artery disease and left ventricular dysfunction. METHODS: One hundred and thirty-five unstable angina patients with 24 h of ST segment monitoring in addition to early cardiac catheterization (4 +/- 3 days) were assessed. Eighty-nine patients (66%) had ST segment shift for a total of 593 episodes (mean duration of 18 +/- 30 mins per episode) of which 92% were asymptomatic. Ten patients had a myocardial infarction and six patients died during the hospitalization. In addition, there were 33 urgent revascularization procedures. RESULTS: With the generalized additive logistic model, various clinical variables were assessed for predicting unfavourable outcomes. Duration of ST shift (P = 0.02) was second only to angiographic severity of coronary artery disease (P = 0.004) as a predictor. In the presence of these two variables left ventricular function did not have independent prognostic significance (P = 0.16). Event-free survival curves show that duration of ST shift of at least 60 mins was of incremental value in predicting unfavourable in-hospital outcomes compared with both the extent of coronary artery disease and left ventricular dysfunction. CONCLUSION: In patients with unstable angina, further stratification can be achieved early with Holter monitoring in addition to coronary angiography and assessment of left ventricular function.

Angina, Unstable↗
PubMed1994

Safety and anticoagulation effect of a low-dose combination of warfarin and aspirin in clinically stable coronary artery disease. Coumadin Aspirin Reinfarction (CARS) Pilot Study Group.

The hypothesis that the combination of low-dose aspirin and warfarin therapy is more effective than aspirin alone in secondary prophylaxis after myocardial infarction is to be examined in the Coumadin Aspirin Reinfarction Study. This pilot study addressed the safety and anticoagulation effect of a fixed, low-dose combination in 114 patients (aged 64 +/- 8 years, 85% men) with stable coronary artery disease receiving 3 mg of warfarin plus 80 mg of aspirin daily for 8 weeks. The international normalized ratio (INR) was measured within 72 hours of initial therapy, and weekly. Of the 110 patients with evaluable INRs, 87 patients (79%) maintained the 3 + 80 mg combination, 19 (17%) had the dose reduced to 1 mg warfarin + 80 mg aspirin, and 4 (4%) discontinued therapy because of a confirmed INR of > or = 4.5. At steady state, patients had INRs of 1.48 +/- 0.41 (3 + 80 mg group) and 1.21 +/- 0.23 (1 + 80 mg group), and inter- and intra-patient variability (estimated by the mean of the between- and within-patient SDs at steady state) was 0.49 +/- 0.08 and 0.13 +/- 0.14, respectively. There was no apparent effect of age on INR distribution. Microscopic hematuria was the most frequent (20%) adverse clinical event, but was unrelated to the INR. Three patients required discontinuation of therapy because of bleeding events (persistent hematuria and epistaxis). A fixed low-dose combination of warfarin and aspirin results in a predictable and stable increase in the INR in a large proportion of patients with coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Importance of ST-segment depression as a determinant of ventricular premature complex frequency after thrombolysis for acute myocardial infarction. Tissue Plasminogen Activator: Toronto (TPAT) Study Group.

Ventricular premature complexes (VPCs) after acute myocardial infarction (AMI) remain important determinants of survival in the post-thrombolytic era. The role of thrombolysis, left ventricular function, and Holter ST-segment depression in modulating VPC frequency is unclear. In a placebo-controlled, randomized study of tissue-type plasminogen activator (t-PA) in 103 patients with AMI (Tissue Plasminogen Activator: Toronto study), VPC frequency and ST depression on Holter monitoring (day 7), ejection fraction by radionuclide scan (day 9), and infarct artery patency and cross-sectional area on day 1 (n = 42) were assessed. After administering t-PA, VPC frequency was 10 +/- 58/hour (mean +/- SD), similar to that after placebo (23.5 +/- 91.7, p = NS). However, patients with ST depression had greater VPC frequency (56 +/- 140/hour) than those without it (1.3 +/- 2.6/hour, p = 0.05). Ejection fraction was negatively correlated with VPC frequency (r = -0.33, p < 0.001). By multivariate analysis, ejection fraction (F = 7.0, p < 0.01) and ST depression (F = 5.8, p < 0.02) were the only independent predictors of VPC frequency. In this placebo-controlled study, VPC frequency after AMI was not related to thrombolytic administration but was associated with ST depression and ejection fraction. This suggests that the underlying extent of both infarcted and ischemic myocardium is important in modulating ventricular arrhythmias after AMI.

Aged↗
PubMed1994

Frequency of transient reductions in left ventricular ejection fraction at rest in coronary artery disease.

To determine the prevalence of decreases in left ventricular (LV) ejection fraction (EF) at rest in patients with coronary artery disease (CAD), including those with stable angina (n = 21), unstable angina (n = 13), and recent myocardial infarction (n = 11), continuous assessment of LV function for 162 +/- 136 minutes was performed using a new nuclear device. The results were compared with those of a group of normal subjects (n = 10) monitored for 80 +/- 28 minutes. Episodes of EF reduction of > 7% from baseline for a total duration of > 5% monitored time occurred in 0 of 10 normal subjects; episodes were more frequent in patients with stable angina (10 of 21, 48%; p = 0.01), with recent myocardial infarction (7 of 11, 64%; p = 0.004), and with unstable angina (11 of 13, 85%; p = 0.0001). The number of EF decreases per hour in patients after myocardial infarction (1.7 +/- 2.5 [SD]) and unstable angina (1.2 +/- 0.7) was significantly more frequent than in normal subjects (0.3 +/- 0.4), but was not different from that in patients with stable angina (0.8 +/- 1.0). The duration of the decrease in EF, expressed as minutes per hour of monitored time in normal subjects (0.7 +/- 1.0%), was significantly less than in patients with unstable angina (10 +/- 8%). Patients with stable angina (6 +/- 9%) and recent myocardial infarction (6 +/- 6%) were not significantly different from normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Does ambulatory monitoring contribute to exercise testing and myocardial perfusion scintigraphy in the prediction of the extent of coronary artery disease in stable angina?

The role of ambulatory myocardial ischemia detection, in addition to exercise testing and myocardial perfusion scintigraphy, in the prediction of the angiographic severity of coronary artery disease in patients with stable angina was examined. Ninety-seven patients underwent ambulatory electrocardiographic monitoring, exercise testing with scintigraphy, and coronary angiography. In addition to the number of diseased vessels involved, proximal arterial segment and coronary artery jeopardy scores were calculated to evaluate the extent of disease and amount of myocardium at risk. Thirty patients (31%) had 1.8 +/- 1.8 episodes/24 hours of ambulatory ischemia (94% of episodes were asymptomatic) and were similar to 67 without ambulatory ischemia in regard to clinical characteristics, left ventricular function and mean number of diseased vessels involved. Proximal arterial segment and coronary artery jeopardy scores were greater in: (1) 30 patients with versus 67 without ambulatory ischemia (3.3 +/- 1.8 vs 1.9 +/- 1.5 [p = 0.0002] and 6.6 +/- 3.6 vs 5.0 +/- 3.4 [p = 0.03], respectively); (2) 78 with versus 19 without a positive exercise test (2.6 +/- 1.8 vs 1.4 +/- 0.8 [p = 0.0001] and 6.1 +/- 3.5 vs 3.0 +/- 2.5 [p = 0.0003], respectively); and (3) 69 with versus 6 without a positive perfusion scan (2.4 +/- 1.8 vs 1.0 +/- 0 [p = 0.0008] and 5.5 +/- 3.6 vs 2.3 +/- 2.0 [p = 0.03], respectively). In multivariate analysis, ambulatory ischemia was the best predictor of the proximal segment score, whereas exercise testing and myocardial perfusion imaging were predictive of the coronary jeopardy score.

Angina Pectoris↗
PubMed1994

Waiting for surgery.

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Health Services Accessibility↗
PubMed1994

Estimating maternal mortality in rural areas of Mexico: the application of an indirect demographic method.

OBJECTIVE: To measure maternal mortality levels in rural areas of Mexico. METHODS: In a cross-sectional study, a census of 13,378 households was carried out in the municipalities of Yecapixtla and Tlaltizapan, Morelos, Mexico. Information on 10,443 subjects from 12 to 49 years old was included in the analysis. An indirect method of measuring maternal mortality--the sisterhood method--was used to estimate maternal mortality. Information about the number of sisters of the interviewees who died due to maternal causes was collected in the census. With this information, estimates of maternal mortality related to a period of 10-12 years before the application of the census were obtained. An innovation to the original method was the calculation of a confidence interval for the estimated maternal mortality rate (MMR). RESULTS: The MMR in this region was 18.68/10,000 live births (95% CI 15.79-21.58/10,000 live births). The average risk of dying due to maternal causes was 1 in 87 for women between 12 and 49 years of age. CONCLUSIONS: The sisterhood method was effective for estimating maternal mortality in a small region, with no previous information about this indicator. The method proved to be useful for identifying a priority region for the implementation of maternal mortality reduction programs. Furthermore, the method was particularly convenient since it was applied as part of a multipurpose survey.

Adolescent↗
PubMed1994

Torsades de pointes ventricular tachycardia following right pneumonectomy: insights into the relation between right cardiac sympathetic nerve damage, QT intervals, and arrhythmias.

Polymorphic ventricular tachycardia in association with prolongation of the QT interval on the surface electrocardiogram (ECG) has long been recognized as an important cause of life threatening arrhythmias that can occur with congenital or acquired abnormalities of cardiac repolarization. One hypothesis of the origin of these arrhythmias states that overactivity of the left-sided sympathetic or under activity of the right-sided sympathetic neural input to the heart leads to prolonged repolarization and ventricular arrhythmias. This hypothesis has led to the application of left cervicothoracic sympathetectomy for control of arrhythmias in congenital long QT syndromes. Although animal models have shown QT prolongation following right stellate ganglionic section or left stellate stimulation, spontaneous ventricular arrhythmias following stellate stimulation or block in man have not been demonstrated. We report the case of a patient with life threatening ventricular arrhythmias following surgical damage to the right cardiothoracic sympathetic nerves.

Electrocardiography↗
PubMed1994

The Latin American Multicenter Trial on psychosocial support during pregnancy: methodology and baseline comparability. Latin American Network for Perinatal and Reproductive Research (LANPER).

This article presents the methodology and baseline findings of a large multicenter trial involving four countries from Latin America (Argentina, Brazil, Cuba, and Mexico). The study was a randomized, controlled, single-masked trial to investigate the impact of social support during pregnancy on perinatal outcomes. Pregnant women with gestational ages between 15 and 22 weeks were screened in health facilities in the four countries. Those presenting with one or more risk factors for having a low-birthweight baby were invited to join the trial. A total of 2235 women--between 500 and 600 in each country--were randomized into an intervention (n = 1110) or a control (n = 1125) group. Both groups were comparable in terms of nearly all baseline variables. The intervention group received a minimum of four visits at home by a trained health worker who provided direct emotional support, health education, and an attempt to enhance the woman's social support network. Over 90% of all women were evaluated at 36 weeks of pregnancy and soon after delivery, and 85% at the 40th day postpartum. The outcomes under study included intrauterine growth retardation, gestational age, perinatal and maternal morbidity and mortality, labor interventions, psychological distress and characteristics of the social support network, among others. This trial showed that it was possible to select, screen, randomize, visit, and evaluate a large number of women in four Latin American countries using a standardized methodology.

Adolescent↗