Correlation of abnormal Q waves, coronary pathology, and ventricular contractility.

Four hundred and ninety-two patients with coronary artery disease underwent analysis of their electrocardiograms, coronary arteriograms, and ventriculograms. Significant Q-waves were correlated with critical coronary occlusions (greater than or equal 75 per cent obstruction) and ventricular contractility. It was found that Q-waves correlate equally well with ventriculographic abnormalities and critical coronary occlusions. The Q-wave correlation varied from 77 to 87 per cent, depending on the area of myocardium under consideration, except for true posterior myocardial infarction, which correlated 55 per cent with ventriculographic abnormalities and 55 per cent with critical coronary occlusions. Significant Q-waves in Leads II, III, and aVF are better indicators of ventriculographic abnormality than in Leads III and aVF alone, whereas Q-waves in the latter two leads are more definitive than in Lead III alone. Patients who have critical coronary occlusions and normal electrocardiograms have normal ventriculograms in 71 to 78 per cent of the cases, again depending on the area of the myocardium under consideration. Thus, the normal electrocardiogram correlates better with the ventriculogram than with coronary pathology. The abnormal electrocardiogram correlates equally well with both.     

The use of the augmented unipolar left leg lead in the differentiation of the normal from abnormal Q wave in standard lead III

An attempt was made to evaluate the diagnostic significance of the QRS pattern in the augmented, unipolar left leg lead (Lead aV_F) as a means of establishing or excluding the diagnosis of posterior infarction. Forty-nine patients were selected for study because of the presence of a prominent Q wave in standard Lead III. One additional patient with posterior infarction was included. This patient did not have Q waves but exhibited the classical ST-T wave changes in Lead III.Multiple precordial and unipolar extremity leads were taken on every subject and esophageal leads were taken on forty-four of the fifty subjects. The presence of a posterior infarct was established in a total of twenty-five subjects, in four of these by autopsy, and in the remaining twenty-one by typical esophageal leads. The infarct was months or years old in all but four cases. Posterior infarction was excluded in a total of twenty-five subjects, in three by autopsy and in the remaining twenty-two by negative esophageal leads.In all cases where posterior infarction was excluded, a prominent Q₃ or QS₃ was present. This amounted to 25 per cent or more of the tallest R in twenty-three of the twenty-five cases; from an examination of the standard leads alone, many of these cases could not be distinguished from cases proved to have old posterior infarction. The pattern of the QRS in Lead aV_F proved to be of considerable help in this differentiation.A QaV_F which was 25 per cent or more of RaV_F was found in twenty-two of the twenty-five subjects proved to have posterior infarct, and in only three of the twenty-five subjects in whom the diagnosis of posterior infarction had been excluded. In both cases of posterior infarct which had a Q₃ but failed to show QaV_F, esophageal leads suggested that the infarct was located high on the posterior wall, near the auricular margin. The voltage of the QRS wave in Lead aV_F was low in two of the three uninfarcted controls which showed a $\text{Q}\text{R}$ ratio exceeding 25 per cent in this lead. In the remaining case, the deep Q wave was present in Lead aV_F when the patient was recumbent, but disappeared when the curve was taken with the patient in the erect posture.The mechanism of production of the Q wave in standard Lead III has been discussed separately for (a) that associated with posterior myocardial infarction, (b) that occurring in uninfarcted hearts with a horizontal or semihorizontal electrical axis, and (c) that occurring in uninfarcted hearts with a vertical electrical axis.     

Occurrence and significance of electrocardiograms displaying large Q-waves in Lead III

Three hundred cases in which there were electrocardiograms with large Q-waves in Lead III, according to the criteria of Pardee, are presented. The majority of these records (268 or 89.3 per cent) were obtained in examination of patients who had one of the following conditions: hypertensive heart disease, the anginal syndrome, hypertensive heart disease accompanied by the anginal syndrome, or arteriosclerotic heart disease not accompanied by the anginal syndrome or hypertension. The remaining thirty-two patients (10.7 per cent) had miscellaneous conditions, but the majority of them had diseases that exert their influence chiefly on the left ventricle. Only three cases (1 per cent) in which the patients apparently had normal hearts were found. In 198 cases (66 per cent of 300) the large Q-wave in Lead III was the only significant electrocardiographic feature present, permitting the conclusion that this abnormality may be considered as an additional diagnostic sign. In the composite group of 977 normal persons studied by various observers there were only two cases (0.2 per cent) in which large Q-waves occurred in Lead III.     

Correlation of electrocardiographic and pathologic findings in lateral infarction

Infarction of the lateral wall of the left ventricle was demonstrated pathologically in 105 cases, which represents an incidence of 65 per cent in a series of 161 cases. The cases of anterolateral infarction and those of posterolateral infarction have been analyzed in previous reports and the present study was concerned with a correlation of electrocardiographic and pathologic findings in twenty-seven cases of primary lateral infarction. These cases were classified into three groups, according to the distribution of the lesion at autopsy: (A) high, (B) low, and (C) midlateral infarction.

1.

A. High lateral infarction, involving chiefly the basal one-half of the lateral wall, but continuing for a variable distance into the apical one-half, was found in fourteen cases. The infarct was limited to the subepicardial layer in one case and was manifested by normal QRS complexes and deeply inverted T waves typical of the findings in pericarditis. Despite the fact that the high lateral infarct was transmural in five cases and subendocardial in the other eight, it was manifested by a diagnostic QR pattern in Lead V₅ or V₆ in only one case. The rarity of abnormal Q waves in Leads V₅ and V₆ of this group contrasted sharply with their frequency in association with infarction of the apical one-third of the anterolateral wall and was ascribed to the fact that high lateral infarcts generally spared most or all of the apical one-third of the anterolateral wall. On the other hand, Lead aV_L yielded a QR pattern which was considered diagnostic of lateral infarction in two cases, strongly suggestive in five cases, and suspicious in four cases. Standard Lead I was not an adequate substitute for Lead aV_L because it failed to show an initial downstroke in five of the eleven patients with Q waves in aV_L, because of greater initial negativity of the right than the left arm. Signs suggestive of infarction in the customary precordial or left arm leads constitute an indication for exploration of the upper precordium and axilla. Leads at the intersection of a horizontal line through the sternal terminus of the third intercostal space with vertical lines in the plane of precordial Positions 3, 4, 5, and 6 were obtained on four patients who were followed to autopsy. In one case, the findings in the customary precordial leads were equivocal, those in Lead aV_L were strongly suggestive, but those in the high precordial leads were pathognomonic of the high lateral infarct found at autopsy. The findings in the high precordial leads taken in conjunction with those in the customary leads in the other three cases aided in establishing the diagnosis and in localizing the position of the infarct.     

Ectopic atrial rhythms in the primate

P-wave polarity was studied in small primates during electrical stimulation of both atria. Negative P-waves in Leads II, III, and aV_F were obtained during stimulation of the lower right atrium near the inferior vena cava, the lower anterior left atrium near the inferior pulmonary vein, and the infero-posterior left atrium. The P-R interval was affected inconsistently. These studies confirm findings originally observed in the canine and human heart, and call for caution in making the diagnosis of “coronary rhythm” and “left atrial rhythm.” The term “ectopic atrial rhythm” seems preferable.     

The relation of unipolar limb leads to precordial and esophageal leads

Multiple semidirect leads from the thorax and esophagus along with the augmented unipolar limb leads were obtained in normal subjects in the recumbent and erect postures during quiet breathing and sometimes during forced expiration and full inspiration as well. If a sufficient number of semidirect leads were taken, the counterpart of the QRS-T pattern of each of the unipolar limb leads could be demonstrated in a precordial or esophageal lead and a pathway along which the QRS-T complex maintained a fairly uniform configuration could be found bridging the gap between the extremity and the point on the thorax near the heart where the corresponding semidirect lead was obtained. From the anatomic position of the corresponding semidirect lead and of the pathway leading into the extremity, it was concluded that the potential variations of a given extremity are dominated by those of the epicardial surface which faces toward that extremity.The findings are presented graphically for five subjects, who were selected as collectively illustrative of the normal variations in QRS-T pattern in unipolar limb leads. The illustrations include the marked variations which may be produced by postural or respiratory shifts in cardiac position. The QRS-T pattern in each of the unipolar limb leads was classified in accordance with the corresponding semidirect lead.The findings in Lead aV_L were classified into the five basic patterns: (1) QRS-T resembling that in semidirect leads over the anterolateral aspect of the left ventricle (Leads V₅ and V₆) and characterized by a prominent R with or without a small Q and/or S, preceded by an upright P and followed by an upright T; (2) QRS-T resembling that in semidirect leads over the anterior aspect of the right ventricle (Leads V₁ and V₂) and characterized by a small R₁ relatively deep S, and by a T wave which is usually upright, but occasionally flattened or shallowly inverted; (3) QRS-T resembling that in precordial leads at the transitional zone (generally Lead V₃) and characterized by a QRS of low voltage, consisting of two or more phases of approximately equal amplitude; (4) QRS-T resembling that in esophageal leads opposite the posterior aspect of the left ventricle and characterized by a relatively small Q and tall R preceded by an inverted P wave and followed by an upright, flattened, or inverted T; and (5) QRS-T resembling that in esophageal leads from behind or above the left atrium and characterized by a relatively deep and prolonged Q and small late R, preceded by an inverted P and followed by an inverted T.The findings in Lead aV_F usually corresponded fairly closely with those in leads from the lower esophagus and stomach and were classifiable into four basic patterns: (a) QRS-T resembling that in precordial leads over the right ventricle (Leads V₁ and V₂) which was associated with Pattern 1 in aV_L as a manifestation of counterclockwise rotation into a horizontal position; (b) QRS-T resembling that in leads at the transitional zone, which was also associated with Pattern 1 in aV_L as a manifestation of less counterclockwise rotation into a semihorizontal position; (c) QRS-T resembling that in leads from the apical portion of the left ventricle (Leads V₅ and V₆ and lower esophageal leads) which might be found in association with any of the five patterns in Lead aV_L, depending upon the degree of rotation on the anteroposterior, longitudinal, and transverse axes into an intermediate, semivertical, or vertical position; and (d) QRS-T resembling that in esophageal leads opposite the posterobasal aspect of the left ventricle, characterized by a distinct Q, tall R, isoelectric to slightly depressed RS-T, inverted, diphasic, or flattened T, and accompanied by Patterns 2 or 5 in Lead aV_L, depending mainly upon the rotation on the longitudinal axis.While the pattern in Leads aV_L and aV_F is subject to marked variation due to the mobility of the ventricles in the left chest, the pattern in Lead aV_R is more uniform due to the fixation of the base of the heart, which faces toward the right arm, by the attachments to the great vessels. The major deflection of ventricular origin in Lead aV_R is derived from the potential variations of the endocardial surfaces and cavities of the two ventricles and consists of a downward QRS and inverted T wave. Minor variations may occur in Lead aV_R, consisting of either or both of the following: (1) a minute initial R transmitted from the epicardial surface of the right ventricle across the anterior chest wall; or (2) a late R which tends to be transmitted from the posterobasal surface of the left ventricle across the posterior chest wall when the heart is rotated backward on a transverse axis.The standard limb leads have been analyzed in terms of unipolar limb leads. If unipolar limb leads and multiple precordial leads are available, standard leads are superfluous, since they contribute no information that cannot be derived more precisely from the unipolar limb leads, studied in conjunction with multiple precordial leads.     

The electrocardiogram in pulmonary embolism

Fifty cases of pulmonary embolism (including twenty-seven autopsy cases) were studied in order to ascertain the kind of electrocardiographic changes produced and their relative frequency. It was found that no constant abnormality occurred, and that a large percentage of patients had either normal, nonspecific changes of no diagnostic significance, or no alteration in abnormalities which antedated the embolism. The distinctive electrocardiographic manifestations described by McGinn and White¹ were encountered, but they were rather infrequent (10 per cent of cases). More frequent were S-T deviations, particularly depression in Leads I and II, and T-wave inversion in Leads III and CF₂. This is in accord with the observations of Love, et al.⁵ In the limb leads these changes roughly simulate those of posterior infarction (depression of S-T₁ and S-T₂, with elevation of S-T₃ and inversion of T₃, as well as the presence of Q₃ and S₁) and, in the chest leads, those of anterior infarction (slight elevation of S-T in CF₂, inversion of T in CF₂, with a diphasic QRS in CF₂). A discussion of the means by which the electrocardiographic changes in pulmonary embolism may be differentiated from those of myocardial infarction is presented. In a few cases serial curves after pulmonary embolism are shown. The lack of a characteristic evolutionary pattern demonstrated the greater utility of CF₂ over CF₄ and therefore also IVF is demonstrated.The diagnosis of pulmonary embolism, it appears to us, must rest on an awareness of its possibility, and the suspicion that it may be present when atypical electrocardiographic features which superficially resemble coronary occlusion are noted. A careful correlation of the clinical and electrocardiographic manifestations is essential for the diagnosis.     

Correlation of the location of coronary arterial spasm with the lead distribution of ST segment elevation during variant angina

The lead distribution of ST segment elevation produced by severe “spasm” of major coronary arteries was correlated with the specific artery involved in a group of 110 cases of variant angina with single vessel coronary arterial spasm made up from eight cases personally observed and 102 cases abstracted from published literature.The most sensitive and specific lead for ST elevation during anterior descending (LAD) coronary arterial spasm was V₃; V₂ was almost as good. For spasm of either the right (RCA) or circumflex coronary artery (CMFX), Leads 3 and aV_F showed ST elevation most frequently; electrocardiographically it was difficult to distinguish between spasm of these two vessels. ST elevation in Leads V₅ and V₆ was not specific, occurring in some cases of spasm of each of the three major coronary arteries. ST elevation in Lead V₁ occurred in either RCA or LAD spas, but never in CMFX spasm. ST elevation in Lead 1 was never seen with isolated RCA spasm.No single lead can detect all cases of transient ST elevation. Simultaneous monitoring of Leads 3 and V₃ would have detected 98.2% of 333 cases of ST elevation reviewed, and addition of Lead aV_L would have detected most of the remainder. These findings should be considered in lead selection for monitoring to detect ST elevation, and in using the ECG to identify spastic coronary arteries.     

The orthogonal electrocardiogram in normal women. Implications of sex differences in diagnostic electrocariodgraphy.

Normal limits of the orthogonal electrocardiogram and vectorcardiogram in adult women, ranging in age from 18 to 90 years, are presented. A comparison of results is made with those of normal age-matched men, and sex differences are analyzed from a total of 960 normal records (510 men and 450 women). For the majority of scalar and vectorial items, significant sex differences were found which in women included shorter QRS duration, smaller vector loops, and decreased P, Q, R, S, and T deflections. The upper normal limits of R_x, R_y, and R_z amplitudes were 11 per cent, 20 per cent, and 30 per cent less, respectively, in women than in men.The sensitivity and specificity of electrocardiographic criteria, for high and low voltage, were significantly affected by these sex differences in amplitudes. For example, as a discriminator between normals and subjects with left ventricular hypertrophy, the upper normal limit of R_x + R_z amplitude sum was 3.10 millivolts in men but 2.50 millivolts in women. Hence, the use of the limit derived from males in a female population would decrease its sensitivity drasticially. Similar discrepancies existed in the sensitivity and specificity of electrocardiographic criteria for low voltage. Since the lower normal limit of R_x amplitude was 0.51 millivolt in men but only 0.35 millivolt in women, a substantial number of normal women would be misclassified as having right ventricular hypertrophy or chronic obstructive pulmonary disease if the limit derived from males was used as a criterion.The absence of Q waves in Leads x and y was a common finding in each age and sex group and carries no diagnostic significance. While initial anterior QRS forces in Lead z were present in all normal men, they were smaller and even absent in 1 per cent of normal women. Hence, greater difficulties in electrocardiographic diagnosis of anteroseptal myocardial infarction in women may be encountered.Mean vectors at the end of QRS (point J) and early part of the ST segment were more inferiorly and anteriorly directed in men than in women. T waves in Lead z were always negative in men, but flat or positive T waves were observed in some of the normal women. Sex differences in the level of point J and the ST segment may have important bearings on the interpretation of exercise electrocardiograms.The shorter QRS duration in women signified the importance of sex-specific limits for ventricular conduction delays.     

Persistent displacement of the RS-T segment in a case of metastatic tumor of the heart

A case of carcinoma of the esophagus with massive metastases to the heart is reported. Serial electrocardiograms displayed persistent upward displacement of the RS-T segment in Leads II, III, and Lead V_F, and in a number of the unipolar precordial leads. It was probably caused by almost continuous acute myocardial injury as the neoplastic tissue infiltrated the cardiac musculature.     

Infarction of the lateral wall of the left ventricle: Electrocardiographic characteristics

Evidence is presented in this paper which suggests that acute infarction in the left lateral wall of the heart produces in the electrocardiogram a depression of the RS-T interval in Lead IV and usually a depression of this interval in Leads I and II. Lead III shows no characteristic abnormalities.The RS-T interval deviation in Lead IV is often more marked when the precordial electrode is placed at or to the left of the apex than when it is put nearer the sternum.The QRS complex is usually unaffected by lateral infarction. Consequently, the electrocardiographic pattern of this lesion can be reproduced by angina of effort.Left circumflex artery thrombosis is usually responsible for infarction in the left lateral wall of the heart. However, when this vessel carries an unusually large part of the myocardial blood supply, its obstruction may give rise to more extensive infarction, with complex electrocardiographic patterns.In some patients with lateral infarction there is very real danger of failing to recognize the fact that a coronary occlusion has occurred because (a) these patients frequently have auricular fibrillation, (b) digitalis action may produce a somewhat similar tracing, and (c) electrocardiographic signs of the lesion may disappear rapidly and completely.The electrocardiographic method is a much less sensitive diagnostic procedure in lateral infarction than it is in anterior or in posterior infarction. Even when several precordial leads are used, a lesion in the left lateral wall of the heart, though incompletely healed, can escape detection.On the basis of electrocardiographic study during the acute stage, it is now possible to classify most large infarcts as anterior, posterior, lateral, or combinations of these three types.     

Subendocardial and transmural myocardial infarction: a five year survival study.

Two hundred seventy-six patients (median age 66 years) were discharged from the hospital following an acute myocardial infarction. Based on their electrocardiograms, they were divided into the following three groups: group 1, 127 patients with transmural infarction, i.e., with Q-wave development; group 2, 98 patients with subendocardial infarction, i.e., with S-T segment changes but without Q-wave development; and group 3, 51 patients with nondiagnostic electrocardiograms but with typical symptoms and enzymatic changes. The five year survival rates were not statistically significantly different (59 per cent, group 1; 51 per cent, group 2; and 41 per cent, group 3). Within the three groups, we found a statistically significant lower survival for (1) patients who were above 65 years of age, (2) patients who had a preadmission history of cardiovascular disease, (3) patients who had heart failure and arrhythmias during treatment in the hospital; and (4) patients who needed medical treatment on discharge. Thirteen per cent of the patients in the latter two catagories died suddenly within the first year. Thirty-three per cent of the patients with all these factors survived five years compared to 83 per cent of the patients with none of these factors. The electrocardiographic changes suggesting transmural or subendocardial infarction were not associated with differences in the long-time prognosis.     

Electrocardiographic changes in patients with acute pancreatitis. Case report and review of the literature

Transient electrocardiographic changes in patients with acute pancreatitis are well known in the literature. Mostly these changes are in the form of T-wave inversion, ST-segment depression, and rarely ST-segment elevation without the presence of coronary artery disease. We report a patient, in whom electrocardiographic changes mimicked acute inferior myocardial infarction with subsequent evolution of Q-waves in the inferior leads and ischaemia in the anterior wall. To the authors' knowledge, this is the first report documenting the evolution of Q-waves on surface ECG in the absence of myocardial necrosis verified by postmortem examination in the patient, who died of cardiorespiratory failure and massive haemoperitoneum as a complication of ongoing acute necrotizing haemorrhagic pancreatitis. The authors also discuss diagnostic and therapeutic options in patients with acute pancreatitis and ECG pattern of acute myocardial infarction. Acute pancreatitis may mimic acute myocardial ischaemia (or infarction) or these two diseases may be present at the same time. In differential diagnosis, selective coronarography might be helpful and it allows also immediate revascularisation. Administration of thrombolytic therapy in such patients is not safe and might end up with fatal consequences.     

The relationship between electrocardiographic changes and early mortality rate in acute myocardial infarction

In 587 patients with acute myocardial infarction (AMI) and no previous MI, electrocardiographically estimated infarct size was related to three-month mortality. Mortality was found to be higher in patients with transmural MI (Q or R-wave changes in standard ECG) than in patients with subendocardial infarction (ST-T wave changes in standard ECG). In patients with anterior MI, precordial mapping with 24 chest electrodes was analyzed four days after arrival in hospital (n = 197). Neither the sum of R-waves, the sum of Q-waves, nor the number of Q-waves correlated significantly with early mortality, although there was a trend towards higher mortality among patients with more pronounced ECG changes. Finally, in patients with inferior AMI (n = 230), neither the sum of R-waves nor the sum of Q-waves in leads II, III and aVF on the fourth day influenced three-month mortality. However, when subtracting the sum of Q-waves from the sum of R-waves, there was a significant correlation between the estimated infarct size and the early mortality.     

P-wave changes in acute coronary artery occlusion

In 40 cases of acute coronary artery occlusion definite changes in the P-waves occurred in 32 patients (80 per cent). These changes consisted for the most part in increase in amplitude of the P-wave of at least 0.5 mm. and occasionally in notching or widening of the auricular complex. In 16 patients (40 per cent) the P-waves measured 2 mm. or more in height in some lead.The change occurred more frequently in Leads I and II rather than in Leads II and III, but always in Lead II. It is suggested that P-wave changes in Leads I and II are associated with left auricular dilatation.The P-waves were larger in the first few days of acute illness when cyanosis, congestion of the lungs, enlarged liver, severe dyspnea or orthopnea were present, and became smaller when there was recovery from circulatory failure. The P-waves were larger when RS-T changes were present and returned to normal when T-wave inversions appeared.There is evidence that the larger P-wave early in acute coronary artery disease is indicative of a dilated auricle, and it is suggested that this chamber takes over a portion of the work of the injured ventricle.The increase in size or the change in shape of the P-wave is one of the electrocardiographic signs of acute coronary artery occlusion.     

Hemorrhagic myocardial infarction associated with aortocoronary bypass revascularization.

Experimentally, hemorrhage and extension of myocardial infarction occur commonly when there is reperfusion after coronary artery occlusion. To investigate this hazard in a clinical setting, we compared the histopathologic picture of myocardial infarction in 44 patients who had undergone aortocoronary bypass: 14 (Group I) had myocardial infarction that predated aortocoronary bypass by 1 to 7 days; 13 (Group II) had infarction 1 to 14 days after the surgery; and 17 (Group III) had infarction 15 to 90 days postoperatively. All 44 patients had two or more coronary arteries with luminal narrowing of more than 75 per cent and patent vein grafts to arteries supplying areas of infarction. Hemorrhagic infarcts were present in 57 per cent of patients (eight of 14) in group I and 38 per cent of patients (five of 13) in Group II, contrasting with 6 per cent of patients (one of 17) in Group III (P < 0.005 and P < 0.05, respectively). In hemorrhagic infarcts, the extravasated blood formed irregular intramural dissecting tracts beyond the area of infarction, and foci of myocardial necrosis were present in the border zones. Infarcts affected more than 50 per cent of the left ventricular muscle in 64 per cent of cases of hemorrhagic infarction and in 13 per cent of cases of nonhemorrhagic infarction (P < 0.05). The prevalence of hemorrhagic infarction after revascularization may account for the high mortality of evolving and perioperative myocardial infarction associated with aortocoronary bypass, and this finding militates against wholesale immediate revascularization in patients who have uncomplicated myocardial infarction.     

The electrocardiogram in late middle life

Within the limits of our experience we may state:The following findings, some of which we have previously considered of doubtful significance, are not pathological.Diphasic or iso-electric P-waves in Lead I or inverted P-waves in Lead III, if they become upright on deep inspiration; slurring of QRS complexes, especially in Lead III and slight to moderate notching of R with the QRS interval below 0.10 seconds, “transverse heart,” isolated left axis deviation, moderate inversion of T-III (this last finding is very common).On the other hand, the following findings were not present in this series and must therefore be looked upon with suspicion.Indeterminate or inverted P-waves in Leads I or II, inverted P-waves in Lead III, if they do not become upright on deep inspiration. Inversion of T-waves in Leads I or I and II, or iso-electric T-waves in Leads I or II if they do not become upright on deep inspiration. A P-R interval exceeding 0.20 seconds, a QRS interval exceeding 0.10 seconds, or an S-T interval exceeding 0.34 or 0.36 seconds (the upper limit seems slightly uncertain).It is seen that for the proper evaluation of a doubtful finding deep inspiration and sometimes change in position may be necessary in any lead. Such thorough investigation should always be done when the electrocardiographic findings may be the determining factor in the diagnosis.This material does not indicate whether an isolated right axis deviation is definitely a pathological sign or whether the inverted wave in a transverse heart is always an S-wave.There do not seem to be any characteristic “age-changes” in the electrocardiogram.     

The electrocardiogram and the “two-step” exercise. A test of cardiac function and coronary insufficiency: Master,A. M., Nuzie,S., Brown,R. C., and Parker,R. C. Jr.: Am. J. M. Sc. 207: 435, 1944

A case of trichinosis, with infestation of the heart and electrocardiographic changes suggestive of marked myocardial damage, is reported.The electrocardiographic abnormalities are not always limited to T-wave changes in Leads II and III and prolongation of the QRS complex, but may include T-wave changes in the precordial leads which simulate those which occur in myocardial infarction.Deviations of the electrocardiogram from normal are dependent upon the amount of damage inflicted upon the myocardium by the trichinellae. The damage undoubtedly varies with the number of invading organisms.