Late potentials recording with a precordial signal-averaged electrocardiogram in 53 consecutive patients with a first acute myocardial infarction: incidence and early natural history.

Signal-averaged electrocardiograms were obtained in 53 consecutive patients with a first acute myocardial infarction (AMI) who survived the first 10 days of hospitalization. The recording was performed twice, at Day 1 and at Day 10 of hospitalization, in patients without bundle-branch block and who did not receive antiarrhythmic therapy. Signal-averaged ECGs were obtained with an instrument which analyzes the presence of late potentials (LP) in each individual precordial lead.

Effects of thrombolysis on the 12-lead signal-averaged ECG in the early postinfarction period.

Signal-averaged ECG has been used to identify patients at risk for ventricular tachycardia and sudden death after myocardial infarction. The goals of this prospective study were to examine the effects of reperfusion achieved with thrombolytic therapy on the 12-lead signal-averaged ECG and on ventricular arrhythmias in the early period after acute myocardial infarction (AMI). A total of 190 consecutive patients with AMI who fulfilled the inclusion criteria were enrolled.

Effect of thrombolysis on the evolution of late potentials within 10 days of infarction.

Patients with late potentials in the signal averaged electrocardiogram are more at risk of lethal arrhythmias in the period after acute myocardial infarction. To test the effects of thrombolysis on the incidence and evolution of late potentials, 158 consecutive patients were prospectively studied during the first 10 days after acute myocardial infarction. The study population consisted of two groups: 93 control patients treated conservatively and 65 patients treated with intravenous thrombolysis.

Power spectrum analysis of fetal heart rate variability using the abdominal maternal electrocardiogram.

A signal analysis procedure is described for obtaining the power spectrum of the fetal and maternal heart rates as recorded from the abdomen. This technique, which includes the subtraction of an averaged maternal ECG waveform using a cross-correlation function and the fast Fourier transform algorithm, enables the detection of all the fetal QRS complexes in spite of their coincidence with the maternal ECGs. The power spectrum of the fetal heart rates (FHR) obtained from 15 women at 32-41 weeks gestation were studied and two indices were measured which are related to the long term and short term variabilities in the FHR signal.

Quantification of the fetal electrocardiogram using averaging technique.

A signal analysis procedure is described for obtaining time intervals parameters of the fetal electrocardiogram as recorded from the maternal abdomen. Applying averaging to the fetal electrocardiogram quantification of the PR interval, QRS duration and QT interval were measured. This technique which includes the subtraction of an averaged maternal ECG waveform using cross-correlation function and fast Fourier transform algorithm, enables the detection of all the fetal QRS complexes in spite of their coincidence with the maternal ECGs.

Increase in nitrosourea resistance in mammalian cells by retrovirally mediated gene transfer of bacterial O6-alkylguanine-DNA alkyltransferase.

Maloney murine leukemia virus-based, replication-defective retroviral vectors containing the neomycin resistance gene (neo) were developed to transfer the Escherichia coli ada gene coding for O6-alkylguanine-DNA alkyltransferase, into mammalian cells. To optimize gene transfer and expression, the following promoters were linked to ada: the Maloney murine leukemia virus promoter within the long-terminal repeat, the Rous sarcoma virus promoter, the thymidine kinase promoter, or the human phosphoglycerate kinase promoter. Sequences were transfected into the helper virus-free retroviral packaging psi-2 cell line.

High frequency electrocardiography of three orthogonal leads in dogs during a coronary artery occlusion.

The ability to detect cardiac ischemia in dogs was studied using high frequency electrocardiography and signal averaging technique. Ischemia was induced via a balloon occluding cuff placed around the left anterior descending coronary artery. Three surface orthogonal bipolar leads (X, Y, and Z) were recorded prior to inflation of the occluding cuff.

Frequency content of the QRS notching in high-fidelity canine ECG.

High-fidelity ECGs, defined as ECG signals including high-frequency components, have been studied and variations in the incidence of fine notches and slurs on the QRS complex were reported in different myocardial pathologies. These observations might be of clinical importance since they suggested a noninvasive marker for cardiac dysfunctions. We studied high-fidelity ECG waveforms displaying pronounced notches and slurs.

Spectral analysis of the fetal electrocardiogram.

The spectral curves of the averaged fetal and maternal electrocardiograms as recorded from the abdomen were studied. The power spectrums were obtained using a technique which includes the subtraction of an averaged maternal ECG waveform using cross-correlation function and fast Fourier transform algorithm. The spectral curves of the averaged maternal and fetal ECG waveforms obtained from 21 pregnant women who had gestation periods of 32-41 weeks were studied.

An improved detection algorithm in fetal electrocardiography.

Fetal electrocardiogram signals from abdominal recordings were digitized and processed by a personal computer. An averaged maternal signal was derived from the cross-correlation function and nonrecursive digital filtering. The cross-correlation function was calculated from the cross-spectrum and the fast Fourier transform algorithm.

The effect of tumor necrosis factor on normal human hematopoietic progenitors.

Tumor necrosis factor-alpha (TNF-alpha), a product of activated macrophages that is cytotoxic to tumor cells, could be used to purge tumor cells from bone marrow before autologous bone marrow transplantation for hematologic malignancies and/or solid tumors. To determine whether exposure to TNF-alpha would have an inhibitory effect on hematopoietic progenitors, we incubated normal human bone marrow with a wide range of concentrations of recombinant human TNF. In order to mimic the conditions that would be used in bone marrow purging, bone marrow cell suspensions were incubated with TNF in doses ranging from 500 to 100,000 U/ml for 24 hours, and were assayed for colony formation in agar.

Altered cardiac repolarization in some victims of sudden infant death syndrome.

Abnormal prolongation of cardiac repolarization, as reflected by a long QT interval with respect to the RR interval on the electrocardiogram, is known to be associated with ventricular tachyarrhythmias. To test the hypothesis that prolonged cardiac repolarization may characterize some babies who die of sudden infant death syndrome (SIDS), we studied the dependence of the QT interval on the preceding RR interval in 10 babies with SIDS and 29 healthy control babies. We analyzed approximately 5000 pairs of QT and RR intervals in each subject over a wide range of RR intervals.

Detection of transient myocardial ischemia by computer analysis of standard and signal-averaged high-frequency electrocardiograms in patients undergoing percutaneous transluminal coronary angioplasty.

Electrocardiographic manifestations of transient myocardial ischemia were studied, in 11 patients undergoing angioplasty (PTCA) of a left anterior descending coronary artery stenosis, by the visual inspection of the standard surface electrocardiogram (S-ECG) and the intracoronary ECG (IC-ECG) as well as computer-assisted analysis of the S-ECG. Cross-correlation analysis (CCA) performed by computer was used to compare beat-to-beat variability in ST-T morphology of the S-ECG during different stages of PTCA. CCA was also applied to the signal-averaged high-frequency QRS (SA-HFQ).

Subtle alterations in the high-frequency QRS potentials during myocardial ischemia in dogs.

The high-frequency components in the QRS complex were examined before and during the occlusion of the left anterior descending coronary artery. ECG waveforms from different stages of the ischemia state were averaged using cross-correlation technique and fast Fourier transform algorithm. The average waveforms were the filtered with nonrecursive digital filters (150-250 Hz) to obtain the high-frequency QRS complex.

Effects of coronary occlusion on high-frequency content of the epicardial electrogram and body surface electrocardiogram.

The very high-frequency content (150 to 250 Hz) of epicardial electrogram waveforms was studied in 19 anesthetized dogs subjected to occlusion of left anterior descending coronary artery. Computer techniques of digital averaging and digital band-pass filtering were applied. Signals were obtained from epicardial electrodes placed in the ischemic left ventricular region and on the noninjured right ventricular surface, and from the body surface electrocardiogram.

Parenteral nutrition in a pregnant cystic fibrosis patient.

This case report describes a 30-year-old pregnant woman with cystsic fibrosis who had marasmus as evidenced by clinical examination. The patient was maintained on central venous hyperalimentation for 18 days in her last trimester. The patient delivered a full-term infant via cesarian section with Apgar of 8 and 9, at 1 and 5 minutes, respectively, and adverse affects.

Signal averaging technique for noninvasive recording of late potentials in patients with coronary artery disease.

An advanced non invasive signal averaging technique was used to detect late potentials in two groups of patients: Group A (24 patients) with coronary artery disease (CAD) and without sustained ventricular tachycardia (VT) and Group B (8 patients) with CAD and sustained VT. Recorded analog data were digitized and aligned using a cross correlation function with fast Fourier transform schema, averaged and band pass filtered between 60 and 200 Hz with a non-recursive digital filter. Averaged filtered waveforms were analyzed by computer program for 3 parameters: (1) filtered QRS (fQRS) duration (2) interval between the peak of the R wave peak and the end of fQRS (R-LP) (3) RMS value of last 40 msec of fQRS (RMS).

A new technique to determine the correlation between the QT interval and heart-rate for control and SIDS babies.

The ability of the autonomic nervous system to alter the QT interval in response to heart rate changes is essential to cardiovascular control. An accurate way to determine the relation between QT intervals and their corresponding RR intervals is described. A computer algorithm measures the RR intervals using digital filtering and cross-correlating the QRS sections of consecutive waveforms.

High frequency electrocardiography using an advanced method of signal averaging for non-invasive detection of coronary artery disease in patients with normal conventional electrocardiogram.

The ability to detect coronary artery disease (CAD) in patients with normal, conventional electrocardiograms (ECG) was studied using high frequency electrocardiography and an advanced method of signal averaging in three groups of subjects. Group A consisted of ten healthy subjects under the age of 30; Group B of 15 patients with chest pains and normal coronary arteries; and Group C of 20 patients with chest pains and CAD. Four hundred ECG waveforms from leads V3, V4 and V5 were recorded, and the recorded analog data were digitized.

Frequency and time domain analysis of airflow breath patterns in patients with chronic obstructive airway disease.

Airflow patterns from patients with chronic obstructive airway diseases (COAD) and normal subjects were analyzed using time and frequency domain analysis. Data were recorded during tidal breathing with a pause between the breaths, digitized at 320 samples per second (10-bit resolution), and processed with a CDC 6600 computer. The appearance of high-frequency components (10-20 Hz) in the time domain waveform and the spectral curve in the power spectrum were studied.

Sarcoidosis, Hodgkin's disease, and autoimmune hemolytic anemia.

Reported is the unique occurrence of sarcoidosis, Hodgkin's disease, and autoimmune hemolytic anemia in the same patient. Although the diagnosis of sarcoidosis preceded that of Hodgkin's disease by 29 years, massive splenomegaly had been present for 13 years before Hodgkin's disease was diagnosed following splenectomy. The known associations of sarcoidosis and Hodgkin's disease as well as each disease with autoimmune hemolytic anemia are reviewed.

Well-differentiated lymphocytic lymphoma with peripheral blood involvement, osteolytic bone lesions, and hypercalcemia. A case report and review of the literature.

It is rare for small lymphocytic B-cell malignancies to be associated with osteolytic bone lesions and/or hypercalcemia. The authors present an unusual case of well-differentiated lymphocytic lymphoma (DWDL) in a 70-year-old man who had osteolytic bone lesions and subsequently developed severe refractory hypercalcemia. The possible etiologic mechanisms responsible for these findings are discussed, and a brief review of the literature is presented.

Cross-correlation technique for arrhythmia detection using PR and PP intervals.

A combined, cross-correlation procedure for computerized arrhythmia detection is presented. It enables the classification of a wide range of arrhythmia and is based upon the determination of both P and QRS waves. The electrocardiogram (ECG) signal is recorded from external leads, digitized (10 bits of resolution) at 1.

The use of cross-correlation function for the alignment of ECG waveforms and rejection of extrasystoles.

The cross-correlation function for alignment of ECG waveforms and rejection of artifacts was studied. ECG waveforms were recorded and digitized (10-bit resolution) at 1.28 KHz and were processed with a CDC 6600 computer.