The lesser electrocardiographic signs of cardiac pain

Importance of notching and slurring of the resting QRS complex in the diagnosis of coronary artery disease

Data on the correlation of coronary artery disease (CAD) and electrocardiographic findings are, except for Q waves, still controversial. The purpose of this study was to determine whether QRS complex notching and slurring (N&S) is of significant value as a diagnostic discriminator in the detection of CAD. This study comprised 500 consecutive patients aged between 24 and 81 years (mean, 53.4 years) who underwent coronary angiography because of chest pain. Patients were evaluated for CAD, angiographic evidence of myocardial infarction (MI), N&S, and abnormal Q waves. Of these 500 patients, 418 had CAD, and 370 of these had significant (> or = 70%) coronary artery obstruction. The remaining 82 patients had normal coronary arteries. The data revealed that the distribution of N&S in the patients with or without CAD was similar in both the inferior and limb leads (P > .05). But the percentage of N&S in more than two contiguous limb leads was higher in the patients with CAD than in the patients without CAD. Notching and slurring in at least one limb lead was found to be of no value in the diagnosis of MI, of wall motion abnormalities, and of significant obstruction. Notching and slurring in the anterior leads is more sensitive but less specific than abnormal Q waves in the same leads in the detection of significant obstruction, anterior MI, and anterior wall motion abnormalities. Notching and slurring in the anterior leads has as much importance as abnormal anterior Q waves in the detection of angiographic evidence of anterior infarct, of anterior wall motion abnormalities, and of significant coronary artery obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of notching and slurring of the resting QRS complex in the detection of ischemic heart disease

The resting 12-lead ECG has long been known to be an insensitive marker of underlying ischemic heart disease (IHD). The purpose of this study was to determine if QRS complex notching and slurring is of significant value as a diagnostic discriminator in the detection of IHD. The data from 205 consecutive patients coming to cardiac catheterization for evaluation of probable IHD were initially analyzed. Eighty-three patients were excluded based upon ventricular hypertrophy, bundle-branch block, lack of data, and pacemaker rhythm. The balance, 122 patients (mean age 61.7 years), were evaluated for angiographic evidence of IHD, ECG findings of QRS notching or slurring, and abnormal Q waves. The data revealed a high prevalence of QRS notching or slurring; 62.2% in those patients with IHD, double the prevalence of significant Q waves (33.3%). The two markers had an approximately equal prevalence (QRS notching or slurring 61.7% vs. Q waves 53.2%) in patients with angiographic evidence of infarction; however, in patients with less than infarct criteria for IHD, the prevalence of QRS notching or slurring was 62.8%, while only 11.6% showed abnormal Q waves. Analysis indicated that QRS notching or slurring has a sensitivity of 62.2% and a specificity of 93.8% for the detection of IHD. The study demonstrates that QRS notching or slurring is a moderately sensitive and a very specific marker of ischemic heart disease in selected patients when using the resting ECG, and is of greatest value in those patients with lesser degrees of ischemic myocardial injury where the prevalence of Q waves is low.

Clinical significance of minor ST-T depression in resting electrocardiogram

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The earliest electrocardiographic evidence of myocardial infarction

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Problems of an electrocardiogram reporting service

One thousand consecutive electrocardiograms (E.C.Gs) of patients with suspected coronary disease recorded in the course of an E.C.G. Service for family doctors have been analysed against the background of the W.H.O. criteria for the diagnosis of myocardial infarction.

Five hundred and sixty seven tracings were abnormal, but only 63 showed conclusive evidence of myocardial infarction, and only six definite evidence that the infarction was recent.

Four hundred and thirty three E.C.Gs showed no definite abnormality, but for reasons which are given, coronary heart disease could not be excluded in these cases.

The family doctor requires an unequivocal answer to the question: Does this patient suffer from coronary heart disease? This analysis shows that the cardiologist with a single E.C.G. and a brief note before him can seldom give it.

Study of High Frequency Components in Electrocardiogram by Power Spectrum Analysis

A method has been developed for recording the power spectrum of the heart's electromotive force for the time interval corresponding to the QRS complex of the conventional electrocardiogram. Standards for healthy, young normals have been established. No significant change was noted in a group of healthy, middle-aged normals without heart disease. Three different patterns, however, were found for patients with ischemic heart disease, with and without evidence of infarction.

Characteristics of the Frequency Spectrum in the Normal Electrocardiogram and in Subjects Following Myocardial Infarction

The results of a study of the sealar electrocardiogram, utilizing a wide-band recorder, expanded time scale and a low-pass filter, indicate that a recorder flat to at least 500 c.p.s. is required for faithful reproduction. With a high-pass filter, measurable residual signals are present at a cut-off frequency of 1,000 c.p.s., or higher. Therefore, to record these, an adequate response at 1,000 c.p.s. or more is reqnired. The high frequency energy of the electrocardiographic spectrum arises from the fast deflections contained in the original waveform. These may occur in a single fast deflection, notching, or both. Whereas, in the normal individual, high frequency energy usually arises from a relatively smooth, fast deflection, in abnormals the fast events may occur in conjunction with notching, and other deformities. Judging from the technic used in this experiment, a variable band-pass filter is valuable as an aid for studying the high frequency components of the electrocardiogram and establishing equipment requirements. Measurement of peak-to-peak voltage of residual signals gives partial but lot clear-cut separation of normal and abnormal subjects and would not seem to add to the value of high-fidelity electrocardiography per se in routine clinical diagnosis. It is possible that root mean square readings, reflecting the total energy content, might give a better separation between normal and abnormal subjects than peak-to-peak amplitude alone.

Additional electrocardiographic signs of cardiac pain

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Polarity and amplitude of the U wave of the electrocardiogram in relation to that of the T wave

The ratio of the amplitude of the QRS complex to the amplitude of the U wave varies in different leads of the same electrocardiogram. In the majority of electrocardiograms, the U wave has the same polarity as the T wave and the ratio of the U wave and T wave amplitude is relatively constant in all leads. The tallest positive U wave is usually observed in the area of leads V 2 to V 4 . The deepest negative U wave is usually observed in the area of leads V 5 to V 6 . Secondary changes of the T wave are very frequently accompanied by similar changes of the U wave. T-wave changes caused by myocardial infarction and digitalis are usually not accompanied by changes of the polarity of the U wave.

The electrocardiograms of 297 cases of hypertension were divided into 6 groups on the basis of the relationship between the polarity of the T wave and the U wave. Both waves were positive in all precordial leads in 48.1 per cent of the cases. Negative U waves were found in 21.8 per cent of the cases and these were predominantly in the leads with negative T waves. A negative T wave in the left precordial leads was accompanied most frequently by a negative, less frequently by an isoelectric, and least frequently by a positive, U wave. An inverted U wave in the presence of an upright T wave was found in only 2.8 per cent of the cases. A change from a negative to a positive or isoelectric U wave was observed after slowing of the heart rate, a drop in blood pressure, and nitroglycerin administration.

Painless cardiac infarction

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The distinctive electrocardiogram of coronary arteriospasm

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