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Biomedical subjects

M H Luria

Publications and source records attributed to M H Luria.

At least 37 records · Page 2Linked to original sources
PubMed1993

Importance of long-duration postoperative ST-segment depression in cardiac morbidity after vascular surgery.

Major vascular surgery is associated with a high incidence of cardiac ischaemic complications. By means of continuous perioperative electrocardiographic recording, we studied 151 consecutive patients undergoing major vascular surgery to find out the characteristics of any myocardial ischaemia and the relation to outcome. 13 (8.6%) patients had postoperative cardiac events (6 myocardial infarctions, 2 unstable angina, and 5 congestive heart failure). There were 342 perioperative ischaemic episodes shown by ST-segment depression; 164 (48%) occurred postoperatively. Postoperative ischaemic episodes were significantly longer than episodes before or during operations (3.2 vs 1.7 and 1.5 min per h monitored, respectively, p < 0.001). Both Detsky's cardiac risk index and long-duration (> 2 h) preoperative ischaemia were predictive of postoperative cardiac complications (odds ratios in univariate analysis 3.3, p = 0.03, and 7.2, p = 0.009, respectively). However, long-duration (> 2 h) postoperative ischaemia was the only factor significantly associated with cardiac morbidity in multivariate logistic regression analysis (odds ratio 21.7, p = 0.001). Long-duration ST-segment depression preceded most (84.6%) postoperative cardiac events, including myocardial infarctions, and no cardiac event was preceded by ST-segment elevation. 5 of the 6 postoperative myocardial infarctions were non-Q-wave infarctions. We conclude that long-duration subendocardial ischaemia, rather than acute coronary artery occlusion, may bring about postoperative myocardial injury and complications.

Aged↗
PubMed1993

Early heart rate variability alterations after acute myocardial infarction.

In order to assess early changes in heart rate variability, we studied 81 patients with acute myocardial infarction during the initial 24 hours after thrombolytic therapy. The standard deviation of the mean heart rate and the low (0 to 0.05 Hz), mid (0.05 to 0.20 Hz), and high (0.20 to 0.35 Hz) frequency band power were evaluated with 24-hour ECG Holter recordings. We found diminished variance in the time domain and reduced power spectrum in the frequency domain compared with a group of 41 normal subjects (p < 0.01). Patients with anterior infarction had significantly (p < 0.01) higher heart rates and lower heart rate variability values than patients with inferior infarction. Reduction in heart rate variability occurred within the first 8 hours in patients with anterior infarction; a significant fall (p < 0.03) was especially noted in the high-frequency band after a decline in ST-segment elevation. Heart rate variability alterations in patients with inferior infarction were most evident in the final 8-hour interval. These findings may be viewed in terms of sympathovagal imbalance and may be related to clinical signs of intense autonomic nervous system activity that are observed early in the course of acute anterior and inferior myocardial infarction.

Aspirin↗
PubMed1993

Comparison of different methodologies of heart rate variability analysis.

Two methodological aspects of heart rate variability (HRV) are tested. Heart rate variability and RR interval variability (RRV) are compared in 109 healthy subjects using 24-h Holter recordings. Autoregressive power spectrum analysis was performed, and the power in three frequency bands was evaluated by two different methods: the peak power and the mean power within the band. The power in the low frequency (LF) and high frequency (HF) ranges showed greater changes between day and night values when RRV was analysed compared with HRV. The mid frequency (MF) range power showed no significant change at night with RRV analysis compared with a significant decrease with HRV analysis. The different pattern of changes between day and night values when using RRV or HRV analysis is explained by the non-linear nature of the relationship between RR interval and heart rate and the lower heart rate at night. Therefore, depending on the heart rate, there may be amplification or attenuation of fluctuations when transforming from one heart rate variability method to another. When comparing peak power and mean power measurements within the frequency bands, the changes in LF and MF powers were similar. However, HF mean power with RRV analysis showed less change at night than the peak power and no change with HRV analysis. The explanation lies in the fact that respiratory fluctuations at night are much more regular, resulting in a sharp high peak in the power spectrum. The peak power is therefore higher at night, whereas the total power changes much less or remains unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Bias↗
PubMed1993

Perioperative myocardial ischemia in carotid endarterectomy under cervical plexus block and prophylactic nitroglycerin infusion.

Perioperative myocardial ischemia was evaluated in 36 consecutive carotid endarterectomy procedures carried out on patients with a high (72.2%) prevalence of ischemic heart disease. The procedures were performed under cervical plexus block plus a prophylactic intravenous nitroglycerin infusion. Findings of myocardial ischemia on perioperative (48 hours) continuous electrocardiogram recordings were correlated with preoperative cardiac status, perioperative continuous intra-arterial blood pressure measurements, and postoperative cardiac outcome. In two patients, ST segment analysis was un-interpretable because of bundle-branch blocks. Altogether, 64 episodes of significant ST segment depression were detected in 18 (52.9%) of the remaining procedures. In 8 (23.5%) procedures, ST segment depressions occurred either during carotid artery clamping at the time of the largest rise in blood pressure or within 2 hours of declamping, when blood pressure tended to decline. There were four (11.7%) postoperative cardiac events: three myocardial infarctions (one Q wave and two non-Q wave) and one episode of unstable angina pectoris. All four patients with cardiac events had early signs of myocardial ischemia either at the time of cross-clamping, or soon after declamping of the carotid artery. All myocardial infarctions developed following prolonged (> 10 hours) myocardial ischemia, starting with the first 20 hours after surgery. Thus, ST segment depression occurring during clamping or soon after carotid declamping was associated with cardiac complications (sensitivity 100% and specificity 86.6%) and suggests the possible usefulness of on-line ST segment trend monitoring.

Aged↗
PubMed1993

Raising HDL cholesterol with low-dose nicotinic acid and bezafibrate: preliminary experience.

Nicotinic acid is an effective agent for elevating HDL cholesterol but is limited by side effects. In order to improve tolerance and lipid levels, we combined low-dose nicotinic acid with bezafibrate. We gave low-dose (mean 435 mg/day) nicotinic acid to 37 patients with low HDL cholesterol, bezafibrate (mean 476 mg/day) to 58 patients with elevated total cholesterol and both agents (mean nicotinic acid 435 mg/day and bezafibrate 512 mg/day) to 25 patients with low HDL cholesterol and elevated total cholesterol. A total of 53 additional patients were followed as controls. Three intervals of treatment were studied: 0-6, 6-12 and > 12 months. The combination of drugs resulted in significant (P < 0.05) percentage changes in total cholesterol, triglycerides and total/HDL cholesterol compared to nicotinic acid alone and significant (P < 0.04) percentage changes in HDL cholesterol compared to bezafibrate alone. It is concluded that low doses of nicotinic acid may result in significant changes in HDL cholesterol; when combined with bezafibrate significant alterations in total cholesterol, triglycerides and total/HDL cholesterol also result.

Aged↗
PubMed1992

Day vs night ECG and heart rate variability patterns in patients without obvious heart disease.

The day vs night values of variables that may be related to the autonomic nervous system were compared in 50 individuals without obvious heart disease. Using ambulatory electrocardiographic monitoring and heart rate variability analysis, it was found that in contrast to daytime, nocturnal heart rate and total heart rate variability were reduced and low (0-0.05 Hz) and high (0.2-0.35 Hz) frequency power of nocturnal heart rate variability were increased, whereas mid-frequency (0.05-0.2 Hz) power was reduced. In addition, nocturnal episodes of trapezoidal-shaped waveforms of heart rate increase were present primarily at night and ST was elevated to a greater extent at night. Many of these factors were related to age and tentatively, despite the small sample size, reflect an age-related diminished autonomic nervous system response. These results serve to establish a circadian basis for comparison when evaluating disease states such as ischemic heart disease and its prognosis.

Adult↗
PubMed1991

Cardiovascular risk factor clustering and ratio of total cholesterol to high-density lipoprotein cholesterol in angiographically documented coronary artery disease.

High levels of cardiac risk factors tend to cluster together and act synergistically. To develop a suitable and practical marker for clustering, we evaluated 380 consecutive patients at the time of coronary angiography. Analyses of lipid, rheologic, clinical and arteriographic profiles indicated a variety of interwoven relations. Because the ratio of total cholesterol to high-density lipoprotein (HDL) cholesterol (total/HDL cholesterol) was closely related to both the presence and extent of greater than or equal to 50% diameter reduction of greater than or equal to 1 coronary arteries, it was used to divide patients into quartiles. Clustering of high- and low-level risk factors was demonstrated in the highest and lowest quartiles of total/HDL cholesterol, respectively (p less than 0.001). The highest quartile may be characterized by an only moderately elevated total cholesterol level but patients in this quartile may have a very low HDL cholesterol level, high triglycerides, a tendency toward high hemoglobin and fibrinogen levels, a history of smoking, previous myocardial infarction and multivessel disease. These results suggest that total/HDL cholesterol serves as a marker not only for obstructive coronary disease but also for a cluster of potentially modifiable risk factors.

Angiography↗
PubMed1990

Atherosclerosis: the importance of HDL cholesterol and prostacyclin: a role for niacin therapy.

Niacin reduces the incidence of non-fatal myocardial way infarction, confers a significant long-term survival benefit after recovery from myocardial infarction, and has had many years of study and usage by the medical community. Recent evidence suggests that via mechanisms which elevate HDL cholesterol and also release endogenous prostacyclin, niacin should be a potent agent in the long-term treatment of atherosclerosis.

Animals↗
PubMed1989

Influence of ethanol on the delivery of intravenous nitroglycerin solutions.

In order to evaluate the surface tension lowering effect of ethanol in intravenous nitroglycerin solutions of varying concentrations, drop size was measured in intravenous transfusion sets that should deliver 60 drops/ml. Ethanol 5% solutions led to a significant decrease in drop volume and a concomitant increase in the number of drops per unit volume, up to 79 drops/ml were observed. The surface tension lowering effect may account for decreases of up to 25% in delivered nitroglycerin when drop counting infusion pumps are used, and may be a factor in the development of apparent tolerance to intravenous nitroglycerin.

Ethanol↗
PubMed1988

Effect of low-dose niacin on high-density lipoprotein cholesterol and total cholesterol/high-density lipoprotein cholesterol ratio.

Niacin significantly alters blood lipid concentrations but its use has been limited because of clinically disturbing side effects. In an attempt to circumvent these drawbacks, 55 patients with cardiovascular disease were given low-dose long-acting niacin, 1 g/d. Treatment was continued for a mean of 6.7 months and lipid values were compared with a non-treated group of 17 patients followed for a mean of 6.3 months. Lipid values did not change in the nontreated group. In the niacin-treated group total cholesterol and triglyceride levels also did not significantly change. High-density lipoprotein (HDL) cholesterol level rose 31% from 1.01 +/- 0.31 mmol/L to 1.32 +/- 0.31 mmol/L and total cholesterol/HDL cholesterol ratio was reduced 27% from 6.4 +/- 1.9 to 4.7 +/- 1.3. Despite these results, 40% of the patients left the study mainly because of side effects. Apart from one patient who developed overt diabetes, of questionable relationship to niacin, no patient developed serious side effects such as jaundice or peptic ulcer as seen with much higher doses of the drug. Although often difficult to administer to patients, niacin, particularly in low dose, deserves consideration as an inexpensive agent especially useful for elevating HDL cholesterol level and altering the total cholesterol/HDL cholesterol ratio.

Aged↗
PubMed1987

Early treatment of acute myocardial infarction with intravenous streptokinase. A high-risk syndrome.

Fifty-one successive patients treated with intravenous streptokinase 1.7 +/- 0.8 (mean +/- SD) hours after onset of symptoms of acute myocardial infarction were evaluated during a three-month posthospital follow-up period. Coronary angiography was performed four to nine days after the initial hospital admission. Twenty-eight patients had a second late angiogram. Forty-one patients had successful reperfusion but only 25% of all patients were without significant clinical cardiovascular manifestations during this period. Postmyocardial infarction angina pectoris occurred in 21 patients, an abnormal stress test result was present in 28 patients, eight patients developed congestive heart failure, and five patients had reinfarction. An intervention with percutaneous transluminal coronary angioplasty or coronary artery bypass graft was performed in 15 (37%) of 41 reperfused patients. A significantly higher intervention rate was present in patients treated with streptokinase within one hour following the onset of symptoms. Early reocclusion (within three months of the infarct) was noted in patients with 60% or more residual stenosis in their infarct-related coronary artery. These patients also had a significantly greater incidence of angina pectoris. Our findings indicate that early thrombolytic therapy of acute myocardial infarction preserves myocardium, and since the infarct-related artery is patent, but narrowed, the jeopardized area is responsible for a high-risk syndrome with an increased likelihood of ischemic symptoms. An early aggressive approach may be indicated, especially for patients with greater than 60% residual stenosis in their infarct-related coronary artery.

Adult↗
PubMed1986

Bradycardia and hypotension following reperfusion with streptokinase (Bezold-Jarisch reflex): a sign of coronary thrombolysis and myocardial salvage.

Acute myocardial infarction, particularly of the inferior wall, is frequently associated with bradycardia and hypotension. This study reports the occurrence of transient bradycardia hypotension (TBH) (Bezold-Jarisch reflex) following thrombolytic therapy with intravenous streptokinase. Of the 52 patients, 42 had successful reperfusion, and 12 of the latter developed reflex TBH. The Bezold-Jarisch reflex occurred in 10 of 24 patients with inferior wall acute myocardial infarction and in 2 of 28 patients with anterior wall infarction (p less than 0.05). The reflex was associated with significantly more non-Q wave infarctions (p less than 0.05) and also with reduction of left ventricular damage, as evidenced by a lower QRS score (4 +/- 3.8 vs 8.9 +/- 5.6, p less than 0.01) and a higher ejection fraction (61 +/- 13% vs 49 +/- 16%, p less than 0.05). Patients with inferior wall acute myocardial infarction were divided into those with TBH (10 patients) and those without TBH (14 patients). TBH was associated with a significantly higher infarct-related regional ejection fraction (60 +/- 19% vs 35 +/- 18%, p less than 0.05). The results of this study confirm previous findings that reperfusion of the inferoposterior myocardium is capable of stimulating reflex TBH. Furthermore, TBH is associated with patency of infarct-related coronary arteries and myocardial salvage.

Adult↗
PubMed1986

Effects of potassium chromate on atherosclerosis prevention and regression in rabbits.

The effect of intraperitoneal injections of potassium chromate on prevention and regression of atherosclerosis was observed in New Zealand White rabbits. In rabbits fed a 1% cholesterol diet for 90 days, potassium chromate injection was not associated with a significant difference in weight, serum cholesterol, total cholesterol content per 8.5 cm aorta, cholesterol content per gram of aorta or percent intima covered with plaque compared to controls. Similarly, significant differences were not seen in rabbits fed a 1% cholesterol diet for 90 days followed by 60 days of potassium chromate or distilled water injections and a standard diet. These results are in keeping with recent studies suggesting a more limited role for chromium in a variety of lipid-related disorders.

Animals↗
PubMed1985

Prevention of myocardial damage in acute myocardial ischemia by early treatment with intravenous streptokinase.

We evaluated the effectiveness of early intravenous administration of 750,000 units of streptokinase in 53 patients with acute myocardial ischemia treated by a mobile-care unit at home (9 patients) or in the hospital (44 patients). Treatment was begun an average (+/- S.D.) of 1.7 +/- 0.8 hours from the onset of pain. Non-Q-wave infarctions developed subsequently in eight patients, whereas all the others had typical Q-wave infarct patterns. In 81 per cent of the patients the infarct-related artery was patent at angiography performed four to nine days after admission. Vessel patency was independent of the time of treatment, but residual left ventricular function was time dependent. Patients treated less than 1.5 hours after the onset of pain had a significantly higher ejection fraction (56 +/- 15 vs. 47 +/- 14 per cent; P less than 0.05) and infarct-related regional ejection fraction (51 +/- 19 vs. 34 +/- 20 per cent; P less than 0.01) and a lower QRS score (5.6 +/- 4.9 vs. 8.6 +/- 5.5; P less than 0.01) than patients receiving treatment between 1.5 and 4 hours after the onset of pain. Patients treated earlier by the mobile-care unit also had better-preserved left ventricular function than patients treated in the hospital. We conclude that thrombolytic therapy with streptokinase is most effective if given within the first 1.5 hours after the onset of symptoms of acute myocardial infarction.

Adult↗
PubMed1985

Long-term follow-up after recovery from acute myocardial infarction. Observations on survival, ventricular arrhythmias, and sudden death.

A long-term 12-year follow-up of 248 patients surviving acute myocardial infarction indicated a cumulative survival of 89%, 68%, 53%, and 45% for 1, 5, 10, and 12 years, respectively. When patients were assessed with five routinely obtained clinical factors, significant prognostic stratification of high- and low-risk survival groups extended throughout the follow-up period. Sudden cardiac death was found to be twice as frequent as nonsudden cardiac death, but a significant relationship between sudden death and complex ventricular ectopic beats could not be defined. The extent of complex features of ventricular ectopic beats such as pairs, multiform, repetitive, and R-on-T was inversely related to survival. During the first year after acute myocardial infarction, frequency of ventricular ectopic beats was also inversely related to survival. A long-term effect of frequency on survival, however, could not be demonstrated.

Actuarial Analysis↗
PubMed1982

Relationship between sex hormones, myocardial infarction, and occlusive coronary disease.

An alteration in sex hormones has been considered a risk factor for myocardial infarction. In this study, estradiol (E2) and testosterone (T) levels were evaluated in healthy firefighters, patients with myocardial infarction acutely and during their convalescence, patients with no evidence of occlusive coronary artery disease on arteriography, and patients with chronic angina pectoris in whom there was at least one vessel that indicated 50% occlusive coronary artery disease. Although T levels were similar in all groups, E2 levels were substantially higher in patients with myocardial infarction and in patients with chronic angina pectoris. These results support the hypothesis that elevated estrogen levels may be a risk factor for myocardial infarction and coronary artery disease, possibly by promoting clotting or coronary spasm.

Adult↗
PubMed1980

Long-term survival after recovery from acute myocardial infarction.

Long-term prognosis following recovery from acute myocardial infarction is related to the extent of myocardial impairment. This is reflected in a variety of clinical laboratory, and electrocardiographic variables which are often routinely obtained during the hospital course of a patient with acute myocardial infarction. When these factors are utilized to produce prognostic indices, patients may be stratified into a variety of survival groups. Results now indicate that very early after the development of an acute myocardial infarction there are sufficient data for the development of a long-term prognostic assessment. This information should improve our clinical approach to the patient recovering from acute myocardial infarction.

Actuarial Analysis↗