Lamar Crevasse

Task force I: Standardization of terminology and interpretation

The development of a soundly based, widely acceptable uniform terminology for electrocardiographic interpretation is difficult. Physicians frequently disagree about the classification of features in an individual record, and similar disagreements occur in reports generated by different computer programs.‘-1s Some disagreement results from technical error, but the remainder arises from differences in measurement technique, terminology and criteria. Standard rules for measurement, classification and description of electrocardiographic features appear desirable to improve patient care by improving the consistency and quality of the report as well as communication between the interpreter and the user. The standards should be flexible enough to provide for continuing incorporation of improvements in electrocardiographic diagnoses, for classification of features from different populations and for different categories of users. Standards for medical procedures are more readily accepted if they are logical, easily understandable and auth0ritative.l’ However, significant variability in electrocardiographic classification persists even when physicians agree to use identical criteria.44 Imprecise identification of the onset and offset of electrocardiographic deflections is one source of variability in classification procedure, but this type of error can be minimized by proper selection of criteria.lzJs There is no comprehensive list of definitions and criteria designed for the use of electrocardiographic interpreters. The New York Heart Association monograph on nomenclature14 focuses on comprehensive cardiac diagnosis rather than the electrocardiographic report. One of the best known digital coding systems, the Minnesota Code, has precisely defined criteria for classifying electrocardiographic features but is more useful in large scale clinical studies than in the interpretation of routine clinical reports.15J6 Types of interpretive statements: Selecting criteria for each electrocardiographic interpretive statement may be more difficult than selecting terminology. Statements can be divided arbitrarily into three types: (1) Type A refers to an anatomic lesion or pathophysiologic state that can be verified by nonelectrocardiographic evidence; this includes hypertrophy, infarction, ischemia, pulmonary disease and drug and metabolic effects. Selection of optimal criteria for type A statements depends on confirmatory nonelectrocardiographic information, which is limited in many instances at present. (2) Type B refers to an anatomic or functional disturbance that is detectable by the electrocardiogram itself (including special intracardiac leads). Criteria for these statements are based on characteristic features, and pertain mostly to arrhythmias and conduction disturbances. (3) Type C refers to electrocardiographic features that do not fit into type A and B categories. These include electrical axis, nonspecific T wave abnormalities, “premature repolarization,” and unusual voltage. It appears reasonable to define interim standards for types B and C statements at this time, with the understanding that they may be modified by additional information. Selection of criteria: For any type of electrocardiographic statement criteria should be selected with regard to sources of uncertainty that determine the accuracy of the statement; this principle is common to all medical diagnoses. 11~17-21 With respect to electrocardiographic diagnosis, numerous sources of uncertainty include physiologic variations from complex to complex or from day to day, variations in recording equipment or technique, recognition and measurement of the recorded wave forms, morphologic and etiologic classification of electrocardiographic features, and inadequate communication between the interpreter and user of the report.2,22*23 Criteria for classification into different categories should not depend on a difference between measurements resulting from chance variations.zJ4 Borderline regions should be defined on the basis of total precision for both the measurement and the criteria. The definition of pathologic states responsible for the electrocardiographic changes is not necessarily precise. This may complicate establishment of valid criteria. The problem of classifying “microinfarcts” in a correlative study of electrocardiographic criteria is one example of this situation.25 Variations in electrocardiographic measurements associated with age and other constitutional factors make it imperative that all comparisons be made between similar population samples. Collection of data from large samples of healthy and diseased populations

A new computer program for analysis of scalar electrocardiograms.

Abstract A computer program for interpreting the adult 12-lead electrocardiogram has been evaluated. Four thousand electrocardiograms were used in the design of the program which was based on the diagnostic logic used in clinical electrocardiographic interpretation. An evaluation of the program so designed was conducted on 1435 other records, 1008 of which were abnormal. Ninety-seven percent of all records were correctly classified by the computer as either normal or abnormal. Ninety-four percent of all contour abnormality statements made were correct and only 6% of contour abnormality statements were omitted. Ninety-three percent of the normal electrocardiograms were correctly analyzed with most errors consisting of minor ST- and T-wave changes. Of the abnormal tracings, 1.2% were called normal. Eighty-two percent of all 1435 records had a completely acceptable computer interpretation.

An assembly for C14O2 collection in metabolic studies for liquid scintillation counting

An inexpensive method for multiple determinations in metabolic studies of oxidation of C14 substrates for subsequent lipuid scintillation counting is presented. As previously reported (1), complete transfer of C14O2 trapped in the collecting vial can be effected in a single operation.

OXIDATION OF CARBON-14-LABELED ENDOGENOUS LIPIDS BY ISOLATED PERFUSED RAT HEART.

Lipids of the rat heart were labeled with carbon-14 in vivo. The production of C14O2 during the subsequent perfusion of these glycogen-depleted hearts with buffer, but without added substrate, provided direct evidence of the oxidation of endogenous heart lipids. The net decrease in phospholipid content alone could account for 75 percent of the total metabolic CO2 formed.

Fibromyxosarcoma of the pulmonary artery: Associated with syncope, intractable heart failure, polycythemia and thrombocytopenia

Abstract This case represents the third reported case of a fibromyxosarcoma of the pulmonary artery. The diagnosis of pulmonary artery obstruction may be confused with primary pulmonary hypertension, atrial myxoma and mitral valve obstruction. The rapid development of intractable right heart failure, syncopal attacks, soft to absent pulmonic sound and fluoroscopic evidence of differential pulmonary artery pulsations without left atrial enlargement suggest the correct diagnosis. Cardiac catheterization and angiography are important adjuncts to the diagnosis. A syndrome comprised of intractable right ventricular failure, recurrent syncope, polycythemia and thrombocytopenia is suggested as being secondary to obstruction of the pulmonary artery.

The Mechanism of the Generation of the Third and Fourth Heart Sounds

A simple unitarian concept of the mechanism of third and fourth sounds is presented. This study demonstrates that the third sound occurs during early rapid diastolic ventricular filling at a time when atrial pressure exceeds ventricular pressure. It is recorded within the ventricle and on the ventricular wall. It coincides with ventricular muscle vibrations. The fourth sound is demonstrated to consist of two components, both occurring when atrial pressure exceeds ventricular. The first component coincides with the peak of atrial contraction, is recorded within the atria, and is inaudible. The second component, which is audible (25 to 70 cycles per second) and follows the first by 0.01 to 0.02 second, is recordable within the ventricle coinciding with the impact of blood from atrial systole against the ventricular wall. These observations demonstrate that the audible third and fourth heart sounds have a common origin in the ventricles and have the same temporal and hemodynamic relationships regardless of etiology.

A new computer program for comparative analysis of serial scalar electrocardiograms: description and performance of the 1976 IBM program.

Abstract An ECG analysis program capable of serial comparison has been written and its performance tested by the authors. The data base consisted of 772 comparisons from patients each having an average of 2.7 ECGs within a 2-month period. In 1939 contour statements, there were 3.3% statements omitted and 6.3% statements erroneously added. In 72 evolving infarctions there were 8.7% statements omitted and 12.5% erroneously inserted. There were 1249 P, Q, QRS, S-T, and T actual measurement changes of which 4.1% were missed. Twelve percent of the measurement change found by the program was not actually present. The program appears clinically acceptable for measurement and analysis of significant serial changes in the majority of ECGs and performs reasonably well in the more difficult task of defining evolution of myocardial infarction.

Localization of Tritiated Digoxin in Dog Myocardium by Electron Microscopic Autoradiography

Five mongrel dogs were given 0.08 mg/kg of tritiated digoxin over a 24-hour period. Left ventricular myocardium was excised and subsequently fixed, dehydrated, and embedded in Epon 812 epoxy resin. Tissue was sectioned and coated with a monolayer of photographic nuclear emulsion and exposed for varying time intervals up to three months. After development these autoradiographs were viewed with the electron microscope. It was found that of the total number of nuclear tracks counted, 75% were found to overlie the sarcomere of the myofibril, 27% to overlie the mitochondria, and 8% to overlie other structures. Of those tracks associated with the sarcomere, 72% were found to overlie the A band. Evaluation of the data obtained and the techniques used are presented.

Congenital heart disease in an adult with the Ellis-van Creveld syndrome.

Excerpt McIntosh (1) in 1933 described a patient who presented with ectodermal dysplasia, polydactyly, and chondrodysplasia. In 1940 Ellis and van Creveld (2) described 2 more patients with similar...

Effect of temperature on metabolism of glucose-U-C14and palmitate-1-C14 in perfused rat heart*

The uptake and major cellular fates ofglucose-U-C 14 and palmitate-1-C 14 in the isolated rat heart perfused in a closed recirculated system at 17, 27, 37 and 40 C. have been determined. Hearts with glycogen present had a rate of contraction proportional to the temperature; coronary flow was well maintained at all temperatures. In hearts which contained glycogen the glucose uptake was nil and no glycolysis, as shown by residual glycogen and net lactate formation, was evident at 17 C.; glycolysis was minimal at 17 C. even though an appreciable glucose uptake occurred. Hearts depleted of glycogen by a 10 minute preperfusion with buffer equilibrated with 95 per cent N 2 : 5 per cent CO 2 were without contraction during the subsequent perfusion, thereby permitting a separation of metabolic effects due to temperature from any effects due to contraction. In these asystolic hearts the uptake of glucose and palmitate was proportional to the temperature. Lactate and CO 2 formation from glucose were minimal at temperatures of 27 C. and below. At hypothermic temperatures uptake and oxidation of palmitate was suppressed less than with glucose. At all temperatures palmitate suppressed glucose oxidation. These results suggested that cardiac muscle during hypothermia depended primarily on lipid, exogenous and endogenous, as a fuel for respiration. If similar alterations in heart cell metabolism occur in man during hypothermia the biochemical changes observed provide additional support for the value of hypothermia.