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Biomedical subjects

M Emdin

Publications and source records attributed to M Emdin.

18 recordsLinked to original sources
PubMed1996

Estimation of the power spectral density in nonstationary cardiovascular time series: assessing the role of the time-frequency representations (TFR).

Spectral analysis of cardiovascular series has been proposed as a noninvasive tool for investigating the autonomic control of the cardiovascular system. The analysis of such series during autonomic tests requires high resolution estimators that are capable to track the transients of the tests. A comparative evaluation has been made among classical (FFT based), autoregressive (both block and sequential mode) and time-frequency representation (TFR) based power spectral estimators. The evaluation has been performed on artificial data that have typical patterns of the nonstationary series. The results documented the superiority of the TFR approach when a sharp time resolution is required. Moreover, the test on a RR-like series has shown that the smoothing operation is effective for rejecting TFR cross-terms when a simple, two-three components series is concerned. Finally, the preliminary application of the selected methods to real RR interval time series obtained during some autonomic tests has shown that the TFR are capable to correctly represent the transient of the series in the joint time-frequency domain.

Algorithms↗
PubMed1993

Immunoradiometric assay of serum myosin as a marker of myocardial cell damage: methodological and clinical evaluation.

We evaluated the performance and analytical parameters of a one-step magnetic IRMA kit for the measurement of myosin in serum. The method uses two monoclonal antibodies selected for their high affinity to the heavy chains of human ventricular myosin. The first antibody is coupled to a magnetic solid phase and the second one is labeled with 125I. The working range of the IRMA (range of myosin concentrations measured with an imprecision < 10% CV) was 250-3600 microU/L and the sensitivity 20.8 +/- 7.2 microU/L. The between-assay variability, evaluated from replicate measurements in different runs of two serum pools was 14.6 CV% for the first pool (259.1 +/- 37.8 microU/L) and 14.3 CV% for the second pool (442.0 +/- 63.1 microU/L), respectively. To evaluate the clinical usefulness of myosin as a marker of myocardial cell damage, serum myosin was measured in patients with acute myocardial infarction (AMI) (n = 9) or subarachnoid hemorrhage (n = 20). The results obtained with the myosin assay were compared with those of two other markers considered specific for myocardial necrosis (CK-MB and myoglobin). In eight patients with AMI, serum myosin was elevated 24-36 hours after the onset of chest pain and reached a maximum at 4-7 days, returning to control levels at 8-11 days. The one remaining AMI patient showed two subsequent peaks in serum CK-MB and myoglobin concentrations (thus suggesting an extension of myocardial necrosis), the myosin concentrations reaching their peak only after 9 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1992

The European ST-T database: standard for evaluating systems for the analysis of ST-T changes in ambulatory electrocardiography.

The project for the development of the European ST-T annotated Database originated from a 'Concerted Action' on Ambulatory Monitoring, set up by the European Community in 1985. The goal was to prototype an ECG database for assessing the quality of ambulatory ECG monitoring (AECG) systems. After the 'concerted action', the development of the full database was coordinated by the Institute of Clinical Physiology of the National Research Council (CNR) in Pisa and the Thoraxcenter of Erasmus University in Rotterdam. Thirteen research groups from eight countries provided AECG tapes and annotated beat by beat the selected 2-channel records, each 2 h in duration. ST segment (ST) and T-wave (T) changes were identified and their onset, offset and peak beats annotated in addition to QRSs, beat types, rhythm and signal quality changes. In 1989, the European Society of Cardiology sponsored the remainder of the project. Recently the 90 records were completed and stored on CD-ROM. The records include 372 ST and 423 T changes. In cooperation with the Biomedical Engineering Centre of MIT (developers of the MIT-BIH arrhythmia database), the annotation scheme was revised to be consistent with both MIT-BIH and American Heart Association formats.

Algorithms↗
PubMed1989

Improved exercise capacity with acute aminophylline administration in patients with syndrome X.

The efficacy of the adenosine receptor blocker aminophylline on exercise capacity in patients with effort ischemia and documented coronary artery disease has been previously documented. In this study the effect of aminophylline on effort electrocardiographic (ECG) alterations and chest pain was tested in eight patients with syndrome X (anginal chest pain on effort, ischemic ECG changes during exercise, positive dipyridamole test, normal epicardial coronary arteries on angiography and absence of coronary spasm after ergonovine). After double-blind, randomized intravenous infusion of aminophylline (6 mg/kg body weight over 15 min) or placebo (20 ml of saline solution over 15 min), the eight patients with syndrome X underwent an upright bicycle exercise stress test on 2 consecutive days. After aminophylline, there was an increase in effort tolerance (aminophylline 7.7 +/- 1.2 min of exercise versus placebo 5.6 +/- 0.9, p less than 0.01) paralleled by an increase of the rate-pressure product (mm Hg x beats/min x 1/100) at 0.1 mV of ST segment depression or at peak exercise (aminophylline 278 +/- 55 versus placebo 230 +/- 24, p less than 0.05). Aminophylline provoked the abolition of ECG signs of ischemia in all eight patients. Thus, at a dosage that should effectively inhibit adenosine receptors, aminophylline infusion exerts a beneficial effect on exercise-induced chest pain and ischemia-like ECG changes in syndrome X. This effect occurs possibly through the prevention of myocardial flow maldistribution elicited by inappropriate adenosine release during effort in the presence of increased coronary resistance at the level of small intramural coronary arteries. This study, however, does not document the ischemic nature of effort-induced pain and ECG alterations in syndrome X.

Adult↗
PubMed1989

Ultrafiltration: a rational treatment for heart failure.

Patients with late-stage congestive heart failure with significant fluid overload respond well to ultrafiltration. The response is relatively long-standing and includes enhanced responsiveness to diuretics. Ultrafiltration is simple and highly cost effective. Furthermore, it possesses many advantages over massive or drastic pharmacological therapy. In the following paper, we report our own experience and review the world literature.

Blood Volume↗
PubMed1988

The contribution of ventricular tachyarrhythmias to the genesis of cardiac pain during transient myocardial ischaemia in patients with variant angina.

The 24-h ambulatory electrocardiograms of 15 patients with both variant angina and ischaemia-related arrhythmias were analyzed to correlate cardiac pain with the following variables: site, type, duration and magnitude of ECG changes, presence and type of arrhythmias and time of occurrence of ischaemic attacks during the 24-h. Apart from sublingual nitrate therapy, Holter monitoring was performed in the Coronary Care Unit (CCU), in the drug-free state in all patients. During a total of 79 days of monitoring, patients had 1385 ischaemic episodes, of which only 30% were painful. The site of ischaemia did not predict the occurrence of pain. Pain was more frequently associated with ST-segment elevation, longer ischaemic duration, increased time to peak ECG change, and greater ST-segment shift and arrhythmias. When the 259 attacks in association with ventricular arrhythmias were compared to the arrhythmia-free episodes, they were more frequently painful for the same duration and magnitude of ECG ischaemic changes. Furthermore, the complexity of arrhythmias increased the probability of cardiac pain. Most ischaemic episodes occurred at night and a decrease in the frequency of painful episodes (apart from those associated with arrhythmias) was apparent. Thus, in addition to electrocardiographic severity and duration of ischaemia, the presence of ventricular arrhythmias and the time of occurrence seem to influence pain perception during ischaemia.

Adult↗
PubMed1988

Improvement of walking distance in patients with intermittent claudication by chronic local therapy with isosorbide dinitrate ointment.

Isosorbide dinitrate ointment (100 mg tid) was directly applied to 30 male patients with stable, documented intermittent claudication on the areas where ischemic pain was experienced. The symptom-free distance walked (DWA) and the maximum distance reached (MDR) basally, after one, three, six, and twelve months were evaluated by means of treadmill stress tests (TSTs) (angle 0 degree-velocity constant/patient). After the basal TST, patients were randomly divided into two groups: placebo group and therapy group (double blind), and a further TST was administered one month later. DWA results were 74 +/- 8 m vs 297 +/- 83 m and MDR results were 163 +/- 22 m vs 506 +/- 86 m in the therapy group (basal vs one month TST: p less than .01) and 94 +/- 24 m vs 96 +/- 15 m and 232 +/- 53 m vs 183 +/- 26 m in the placebo group, respectively (basal vs one month TST: NS). Being confident that a significant placebo effect was absent, the authors opened the trial and treated all patients, repeating further TSTs at three, six, and twelve months. The following results were obtained: DWA was 84 +/- 13 m, 316 +/- 63 m, 374 +/- 55 m, and 452 +/- 61 m; and MDR was 197 +/- 29 m, 431 +/- 59 m, 514 +/- 57 m, and 547 +/- 59 m, respectively, in basal conditions and after three, six, and twelve months of treatment (p less than .01 for all the values for both DWA and MDR vs basal values).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1987

Findings from long-term electrocardiographic monitoring of patients with variant angina in a coronary care unit.

Eleven patients with frequent episodes of variant angina underwent 24-hour electrocardiographic monitoring in a coronary care unit for a total of 70 days to assess circadian variation in ischemic episodes and its correlation with circadian heart rate (HR) rhythm. In each patient a series of 4 to 13 consecutive days, in the absence of therapy, with 8 or more ischemic episodes per day were analyzed. Harmonic regression models were fitted to the hourly number of ischemic episodes and the hourly values of HR. Out of 54 days, with 8 or more episodes per day for a total of 1,357 episodes, a circadian rhythm was observed for 34 days (64%), in at least 1 day in all patients and during the entire period of observation in only 3. Its presence was independent of the number of episodes; the peak of periodic functions occurred at 2.9 +/- 2.7 AM. A cadian rhythm for HR was observed in 61 of the 70 days (87%), consistently in 7 patients; the nadir occurred at 2.4 +/- 1.5 AM; simultaneous cycling in HR and transient ischemia was found on 32 days. The intrapatient difference between the peak and the nadir of the ischemic and the HR function was, on average, 2.6 +/- 3.3 hours. Thus, a circadian rhythm of ischemic episodes was present in all patients although it was not consistently present; simultaneous occurrence of circadian variation in ischemic episodes and HR was observed only in 60% of the days with a sufficiently high number of attacks and when this occurred, a significant phase shift was observed; occasional loss of HR cycling was observed in some patients, without an apparent cause.

Adult↗
PubMed1987

[Ambulatory electrocardiography in patients with angina pectoris].

In the diagnosis of ischemic heart disease, long-term ECG recording has several distinct advantages. It allows one to relate patient symptoms to cardiac disturbances and to detect asymptomatic events, reveals the possible ischemic genesis of arrhythmias, and it is the most suitable method to assess the acute and chronic effectiveness of treatment and the evolution of the disease. In spite of these advantages, Holter monitoring has several limitations: the analysis of a single lead, is responsible in most systems for the low sensitivity in detecting ischemia occurring in unexplored regions; the period of 24-48 hours may not be sufficient for screening patients due to the unpredictable spontaneous variability of the disease; a common standard of analysis is still lacking even if the European Communities concerted action in Ambulatory Monitoring could represent the solution to this problem. Nevertheless the role of Holter monitoring appears essential in the ambulatory screening of patients with suspected ischemia for a better characterization of patients with ascertained myocardial ischemia, and for the evaluation of treatment and of the evolution of the disease.

Angina Pectoris↗
PubMed1986

Detection of spontaneous episodes in post-infarction angina. Comparison between CCU and Holter monitoring.

The objects of this study are: to evaluate the incidence of early post-infarction angina in patients who developed transmural infarction (Q-AMI) or sub-endocardial infarction (no Q-AMI) during hospitalization; to compare data obtained from patients monitored in Coronary Care Unit (CCU) with those obtained from Holter monitoring. The 107 patients under study (55 with Q-AMI and 52 with no Q-AMI) presented the acute event on average 7.4 and 5.1 days after admittance in the CCU, respectively. A history of angina was present in all except 1 patient with Q-AMI and in all with no Q-AMI. After AMI the angina disappeared in 22 of the patients with Q-AMI and in 31 with no Q-AMI, while it continued in 33 and 21 of these patients, respectively. Twenty-one patients underwent ECG recording according to the Holter technique while in CCU, for an average of 4.4 days before and 5.2 days after the onset of AMI. The comparative analysis of the results obtained from the CCU and from Holter monitoring shows that the CCU greatly underestimates the number of ischaemic episodes, even when pain is present (4.5 episodes per patient per day before AMI and 2 after, versus 13.7 and 6.8 with Holter monitoring). The number of ventricular arrhythmias also seemed lower when analysing data from CCU monitoring. These data demonstrate the importance of Holter monitoring, even in patients admitted to a CCU, for a precise evaluation of the ischaemic and arrhythmic phenomena.

Adult↗
PubMed1986

Electrocardiographic monitoring: temporal versus spatial information and data processing.

In the diagnosis of ischemic heart disease, long-term electrocardiographic recording has several distinct advantages. It allows one to relate patient symptoms to cardiac disturbances and to detect asymptomatic events, furnishes the whole spectrum of electrocardiographic alterations accompanying ischemic attacks, reveals the possible ischemic genesis of dysrhythmias, and is the most suitable method to assess the acute and chronic effectiveness of treatment and the evolution of the disease. In addition to its valuable application in the screening and follow-up of ambulatory patients, its use in the Coronary Care Unit is of great interest, being in this context much more sensitive than visual electrocardiographic monitoring. In spite of these advantages, Holter monitoring has several limitations: the recording and replay systems are below recommended standards; the analysis of a single lead is responsible in most systems for the low sensitivity in detecting ischemia occurring in unexplored regions; the period of 24-48 hours, usually adopted for Holter monitoring, may not be sufficient for screening patients with suspected myocardial ischemia due to the unpredictable spontaneous variability of the disease; a common standard of analysis is still lacking and a reliable computerized analysis is needed to manage data overflow. In conclusion, although further research and technical developments are desired to improve reliability and data processing, the role of Holter monitoring appears essential in the ambulatory screening of patients with suspected ischemia for a better characterization of patients with ascertained myocardial ischemia, and for the evaluation of treatment and of the evolution of the disease.

Angina Pectoris, Variant↗
PubMed1984

[Isosorbide dinitrate ointment in the long-term treatment of intermittent claudication].

We evaluated the long-term therapy with Isosorbide Dinitrate Ointment (ISDN-O): 300 mg daily on the painful leg area in 20 male patients (pts) affected by Intermittent Claudication. The efficacy of the treatment was assessed on the basis of the subjective evaluation of pain threshold (daily diary) and objectively by repeated treadmill stress tests performed by each patient at a constant speed, selected according to the severity of symptoms, and by the evaluation of changes both of the distance walked without symptoms (DWS) and of the maximal distance reached (MDR). The maximal duration of the test was 15 minutes independently from the speed. The reproducibility of treadmill tests and the acute effect of isosorbide dinitrate ointment administration were preliminarly evaluated in 2 groups of 5 patients each. The distance walked without symptoms and maximal distance reached in two control stress tests performed in two successive days were: distance walked without symptoms 37 +/- 29 vs 36 +/- 22 m (NS) and maximal distance reached 97 +/- 40 vs 98 +/- 37 m (NS). During the control period and 1 hour after the drug administration distance walked without symptoms was 34 +/- 31 vs 43 +/- 50 m (NS) and maximal distance reached 89 +/- 53 vs 97 +/- 57, (NS) respectively. In a group of 5 patients the effect of one month administration of placebo was evaluated: distance walked without symptoms was m 68 +/- 29 and m 104 +/- 62 and maximal distance reached was m 156 +/- 103 and m 188 +/- 97 basally and after 1 month of placebo (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Relationships between cardiac pain and objective markers of transient myocardial ischemia.

Cardiac pain is a key symptom for diagnosis of myocardial ischemia in man, even if a minority of transient myocardial ischemic episodes are painful. A multiparametric monitoring approach - associating non-invasive and invasive monitoring techniques during transient myocardial ischemia with and without pain - allows to achieve a clinical diagnosis and obtain information about the pathophysiology of the anginal syndrome.

Coronary Disease↗
PubMedDate not supplied

Clinical characteristics of anginal pain in man.

The clinical recognition of the cardiac origin of chest pain or discomfort on the basis of the description made by the patient, is often difficult. Nevertheless, considering the importance of the correct diagnosis of such syndrome, much work has been done in this field. In this report we will comment data from the literature and from our own, on the quality, duration, irradiation and on the precipitating or relieving factors that are more frequently associated with anginal pain.

Angina Pectoris↗
PubMedDate not supplied

[Increase in tolerance to physical effort in patients with X syndrome after acute administration of aminophylline].

Myocardial flow maldistribution and transmural steal phenomena, due to excessive arteriolar dilation elicited by elevated adenosine release during exercise, might be the mechanism of myocardial ischemia in patients with syndrome X. The effect of the adenosine receptor blocker aminophylline (AM) on effort ischemia in patients with syndrome X was tested: following double blind, randomized intravenous infusion of aminophylline (6 mg/kg over 15 minutes) or placebo, 8 patients with syndrome X underwent exercise stress test. After AM administration there was an increase in work tolerance (AM = 7.7 +/- 1.2 minutes of exercise vs placebo = 5.6 +/- 0.9, p less than 0.01) paralleled by an increase of the ischemic threshold, evaluated through the rate pressure product (mmHg x beats/min x 1/100) at 0.1 mV of ST-segment depression or at peak exercise (AM = 278 +/- 55 vs placebo = 230 +/- 24, p less than 0.05). AM prevented the occurrence of ischemic ECG signs in all 8 patients. Thus, at a dosage which effectively inhibits adenosine receptors, aminophylline infusion exerts beneficial effect on exercise induced ischemia in syndrome X, possibly through the prevention of transmural steal phenomena, elicited by inappropriate adenosine release during effort.

Adult↗
PubMedDate not supplied

Transient myocardial ischemia and cardiac pain. Importance of duration of ischemia, heart rate behaviour and circadian distribution.

In 40 drug-free patients 2052 episodes of transient myocardial ischemia (28% painful) were recorded by 24-h ambulatory ECG. Pain was more frequently associated with longer duration of ischemia and greater ST segment shift and with the presence of ventricular arrhythmias within the ischemic episode. Heart rate always showed a growing trend during the ischemic episode. Circadian distribution of painless ischemic episodes showed a maximum peak at 2 a.m. while the most painful attacks occurred early in the morning (6 a.m.).

Bradycardia↗