284 Annotations Am. Heavt J. August, 1962

cardiac failure find confirmation in a recent paper by Scott,3 who has shown that in these conditions stainable fat appears in the myocardium but, apart from a few exceptions, is not seen in stillbirths or in neonatal deaths, in which there is no evidence of cardiac failure. When present, the fatty change tended to occur earlier in the right heart, but in older babies both ventricles were equally involved. The amount of fat present appeared to be related to the duration of cardiac stress, and this was es- pecially noticeable in those in whom death was due to hyaline membrane disease.

Cardiac metabolism was not studied in any great detail but several interesting points did arise. Ob- viously, some metabolic derangement was present. Normally, glucose, lactate, pyruvate, and non- esterified fatty acids are the main sources of energy available to the heart. For each of these there is a definite threshold of estraction. In the majority this is near zero, but in the case of glucose the thres- hold is much higher, 59 + 6 mg. per cent.6 Levels of blood sugar in the newborn infant are frequently below this level, especially in the case of prematurity, in which instance the custom is to keep the baby without food for the first 2 days. Thus, it is not surprising that under these circumstances the myo- cardium should have to derive most of its energy from the oxidation of fatty acids. This is certainly in line with recent research.’ It is more difficult, however, to explain why the fat should appear in stainable form. One can only postulate that with the increasing effort and progressive anoxia some upset in catabolism must occur and, although the fat is available, it can no longer be utilized ade- quately.

The deposition of glycogen in these hearts was also studied. Even though it was realized that no great stress could be placed on a histochemical method such as this, it was interesting to note that

A therapeutic dilemma)

The conditions of modern life being what they are, the term “dilemma” seems to stare at us with in- creasing frequency. A dilemma is a type of impasse in which a choice must be made between two equally undesirable courses of action. The situation in which the therapeutic and toxic doses of digitalis overlap presents such a dilemma. It may be formally stated as follows: If adequate digitalis is given, the patient will develop digitalis intoxication; if digitalis is withheld, heart failure will result.

Formal logic suggests three solutions for the individual impaled on the horns of a dilemma.’ The first is escape through the horns. This implies finding a third course of action, and in terms of our particular problem would mean an alternative to giving digitalis or not giving digitalis. Since these two courses allow for no others, this approach must be abandoned. The second approach is to

gross depletion of glycogen was usually found only in those hearts which showed the most marked fatty change. In other words, the reserve of glycogen would appear to be called upon only as a last emer- gency, a finding which agrees with the experimental work of Fletcher and Waters.*

1.

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4.

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6.

7.

8.

Jeas &I. Scott, M.D. Research Departnzext

Glcsgow Royal Maternity Hospital Glasgow, Scotland

REFERENCES

Brown, Ii. J. K.: Respiratory difficulties at birth, Brit. M. J. 1:401, 1959. Burnard, E. D.: Changes in heart size in the dyspneic newborn baby, Brit. M. J. 1:1495, 1959. Scott, J. M.: Fatty change in the myocardium of the newborn, Brit. M. J. 2:1746, 1961. Rowe, R. D., and James, L. S.: The pattern of response of pulmonary and systemic arterial pressures in newborn and older infants to short periods of hypoxia, J. Pediat. 51:5, 1957. Adams, F. H., and Lind, J.: The physiologic studies on the cardiovascular status of normal newborn .infants (with special reference to the ductus arteriosus), Paediatrics 19:431, 1957. Olson, R. E.: Myocardial metabolism in COII- gestive cardiac failure, J. Chron. Dis. 9:442, i959. Bing, R. J., Siegel, A., Ungar, I., and Gilbert, M.: Metabolism of the human heart. II. Studies on fat ketone and amino acid metabolism, Am. J. Med. 16:504,19.54. Fletcher, J. P., and Waters, E. T.: The utiliza- tion of various metabolites (blood fat and lactate, cardiac and lung glycogen) in the aglycemic heart-lung preparation, J. Physiol. 94:3x37, 1938.

ride one of the horns, or to create the counterdi- lemma. Ruby’ gives the following example. A young man contemplating marriage may reason thus: “If I get married I will be forced to assume grave responsibilities and worries; on the other hand, if I remain single I will be lonely.” Creating the counterdilemma would be to point out that he is actually faced with two desirable choices: either he can marry, in which case he will not be lonely, or he can remain single and carefree. In terms of our therapeutic dilemma, we can state that, one can give digitalis, in which case the patient, al- though intoxicated, at least will be out of heart failure, or one can withhold digitalis and avoid digitalis intoxication, although a degree of heart failure must be accepted. Few clinicians would be consoled by such a counterdilemma.

The third solution is to take the dilemma by

A nnotutions 28.5

the horns, or to attack the dilemma by showing that the major premises are false. This is the most promising approach in the proposed situation. Taking the first premise-that adequate digitalis results in intoxication-one should remember that even though this may be true at one time, it may not be true at all times for a given patient. Circum- stances, such as heart failure, electrolyte imbalance, and respirator-v failure, may temporarily alter the response to digitalis. If these can be corrected with- out digitalis, one may then find that the therapeutic and toxic doses of digitalis no longer overlap. If heart failure is treated by other means, digitalis may then be used to prevent its recurrence. Others have attacked the first premise by attempting to demonstrate that certain digitalis preparations have wider margins of safety. This proposition, vigorously defended by some, has not won general acceptance.

:Zttacking the second premise of the dilemma means permanently treating the heart disease by means other than the use of digitalis. Heart failure and digitalis have become so inseparably linked in the minds of many that we may forget that digitalis

is not the only answer to the treatment of heart disease; in many cases it is not even a very good one. Valvular heart disease, pulmonary heart dis- ease, and congenital heart disease, for example, respond rather unsatisfactorily to digitalis. Acute pulmonary edema will usually respond well to tourniquets, reduction of anxiety and respiratory effort, defoaming agents, and positive pressure breathing. For the treatment of chronic heart failure, restriction of activity, a low-salt diet, diuretics, treatment of metabolic disturbances, treatment of respiratory failure, appropriate heart surgery, and reduction of hypertension may render digitalis relatively unimportant.

Robert Gilbert, M.D. Depavtnzent of Medicine

State Lrniuersity of New k’ouk lIpstate Medical Center

Syracuse, ,V. I-.

REFERENCE

1. Ruby, L.: Logic, An Introduction, Chicago, Ill., 1950, J. B. Lippincott Company, Chapter 13.

Use of computers in ECG interpretation

The electrocardiogram was selected for a pilot project in electronic data processing (EDP) of cardiovascular information. The electrical heart signals are repetitive and, therefore, well suited for mathematical analysis. The first problem which needed to be solved was the selection of appropriate ECG leads for EDP. The 12 leads which are gener- allv used in clinical electrocardiography would re- quire 12 input channels for recording since the acquisition of simultaneous data is desirable in order to maintain phase relationships. Decreasing the large expense for recording equipment by se- lecting a few leads out of 12 must necessarily be arbitrary because no quantitative studies are known for determination of the information content of single leads. It was found, however, that a large part of the standard 12-Iead information is redun- dant.’ Since ECG information is derived to a great extent from its spatial characteristics, simultaneous recording of 3 orthogonal leads appears to be a rational choice. Both scalar and vectorial analysis can be performed on such records. In a previous study’ it was found that the clinical information contained in 12-lead records is also available from orthogonal 3-lead tracings. This finding could be corroborated later on the basis of several thousand orthogonal records. Thus, a reduction of data by a factor of 4:l appears to be possible without loss of clinical information. Such reduction of data is most important in any EDP project because large amounts of data may esceed computer capacities,

Magnetic tape recording and storage appeared to be best suited for EDP because reproduction of

the original ECG analogue voltages is necessary regardless of whether analogue or digital computers are considered for data processing. The greater flexibility of digital computers was considered to be advantageous in the development phase of the project. Once a set of optima1 analytical procedures has been determined a special-purpose analogue computer may be designed for automatic ECG analysis. The choice of a digital computer made it necessary to obtain an automatic analogue-to-digital converter2 in order to make the original analogue information compatible with digital computers. Voltages of each lead are measured at intervals of 1 millisecond and re-recorded in numerical form on digital magnetic tape. Consequently, they are fed directly into a commercially available digital computer (IBILI 7090) for data processing and analysis.

Since the ECG consists of several distinct wave forms with different electrophysiologic significance, a first computer program had to be developed for automatic recognition of the beginning and the end of these waves.3 A digital filter of the moving average type was applied first in order to eliminate A.C. interference, muscle tremor, and other arti- facts. Consequently, the spatial velocity was de- termined on the basis of the 3 orthogonal com- ponents. It was found that a critical velocity. limit of 3 pVuV/msec. was not exceeded during T-P, P-R, and S-T segments. The point at which this critical value is reached indicates the beginning of a wave. Values below this level are found at the end of waves. This computer program led to measurements