Howard B. Burchell

Serum Potassium and the Electrocardiogram in Hypokalemia

A definite correlation can be established between the electrocardiogram and the serum potassium level at hypokalemic levels. A study was made at the Mayo Clinic of 130 hypokalemic patients with relatively stable clinical states. Variations in Q-T intervals, P-R intervals, atrial rhythm, P waves, T/R values, and T-wave and U-wave contour in hypokalemia were noted as were the relationships between the T-U complex, electrical repolarization phenomena and potassium metabolism. Since modifying factors such as drugs, certain electrolyte disturbances, variations in cardiac rate, conduction defects, and myocardial ischemia were eliminated by careful selection of patients, only the influence of acid-base imbalance, sodium-potassium ratio, and hypertension on the electrocardiogram was studied. Acid-base imbalance and hypertension often simulated or obscured electrocardiographic evidence of hypokalemia. Electrocardiographic criteria of hypokalemia include various combinations of the following signs: (1) T/U value of 1 or less in lead II or V3, (2) U-wave amplitudes of greater than 0.5 mm. in lead II or greater than 1 mm. in V3, and (3) S-T depression of 0.5 mm. or more in lead II or leads V1, V2, and V3. It must be remembered that a normal electrocardiogram does not exclude hypokalemia and that an electrocardiogram which fulfills the established criteria does not necessarily indicate hypokalemia unless the factors discussed have been eliminated or minimized.

Endocardial and Intimal Lesions (Jet Impact) as Possible Sites of Origin of Murmurs

This series of papers constituted the second Symposium on Cardiovascular Sound conducted in association with the Scientific Sessions of the American Heart Association. The symposium took place on Friday, October 25, 1957, at the Hotel Sherman in Chicago. The chairman of the morning sessions was Dr. Hans H. Hecht of Salt Lake City; Dr. J. Willis Hurst of Atlanta was chairman for the afternoon sessions. The first symposium was published in Circulation 16: 270, and 414, 1957. This publication was made possible by a grant-in-aid front the National Heart Institute, U.S. Public Health Service, and by contributions from Mr. Arthur L. Humphries, The Rena and Walter Burke Foundation, Lakeside Laboratories, Burroughs-Welcome Company, and the Wyeth Laboratories.

Relation between Structural Changes in the Small Pulmonary Arteries and the Immediate Reversibility of Pulmonary Hypertension Following Closure of Ventricular and Atrial Septal Defects

The relative importance of organic changes and vasoconstrictive influences in the production of increased pulmonary vascular resistance in congenital heart disease is problematic. With use of a grading system previously described, a study was made of the relation between each of the grades of hypertensive pulmonary vascular disease associated with ventricular or atrial septal defects and the change of pulmonary artery blood pressure immediately following closure of the abnormal communications. The immediate reversibility of the pulmonary hypertension varies inversely with the severity of the structural changes.

Graded Pulmonary Vascular Changes and Hemodynamic Findings in Cases of Atrial and Ventricular Septal Defect and Patent Ductus Arteriosus

With use of a previously described system of grading, a study was made of the relation between each of the grades of hypertensive pulmonary vascular disease and the hemodynamic findings in the lesser circulation in 15 cases of atrial septal defect, 19 cases of ventricular septal defect, and 6 cases of patent ductus arteriosus.

Isolated Ventricular Septal Defect of the Persistent Common Atrioventricular Canal Type

Among 60 necropsy specimens of isolated ventricular septal defects and more than 300 cases of ventricular septal defect observed at operation, 15 cases demonstrating unusual anatomic positions of the defect were found. The ventricular defect differed from the ordinary ventricular septal defect in that it usually occupied the position of the ventricular component of the defect in persistent common atrioventricular canal. For this reason it was named ventricular septal defect of the persistent common atrioventricular canal type. Deformities of one or both atrioventricular valves were common (nine of 15 cases). No atrial septal defects of the ostium primum type were present. Anatomic studies of the conduction tissue revealed that this tissue skirted the posterior and inferior aspects of the ventricular septal defect and that, as in persistent common atrioventricular canal, the course taken by the conduction tissue was unusually long, as a result of the peculiar posteroinferior position of the lower edge of the defect. The electrocardiographic features were striking. In all cases the mean electrical axis of the QRS lay above the isoelectric point; the vector loop obtained in the frontal plane from the scalar electrocardiogram was directed counterclockwise, and its main mass was above the zero line. In addition, in all cases there were signs of right ventricular overload, and in some cases of left ventricular overload as well. Electrocardiographic findings of this pattern have been thought by some authors to be diagnostic of persistent common atrioventricular canal, but we observed that they also occurred in each of the cases of isolated ventricular septal defect of the variety described herein. We recognize that in the usual variety of ventricular septal defect this electrocardiographic pattern occurs, but it does so uncommonly. We have not studied its exact incidence. The anatomy, hemodynamics, and surgical considerations are different in cases with this defect from those with persistent common atrioventricular canal. The surgical risk in these cases has been higher than that in the usual type of ventricular septal defect. In the discussion of the electrophysiologic theories that seek to explain the unusual electrocardiographic patterns in this group of cases, a new theory is offered, based on studies of the conduction system. In our opinion, the different orientation of the advancing fronts of depolarization is the result of congenital displacement of the bundle of His in its relation to the ventricular septal defect.

Demonstration of Differential Effects on Pulmonary and Systemic Arterial Pressure by Variation in Oxygen Content of Inspired Air in Patients with Patent Ductus Arteriosus and Pulmonary Hypertension

Seven cases of patent ductus arteriosus with pulmonary hypertension and reversal of the usual direction of flow are described. Breathing of a low oxygen mixture either initiated or increased the reversed shunt, and breathing 100 per cent oxygen produced the reverse effect. Differences in oxygen saturation and dye-dilution curves recorded simultaneously from the radial and femoral arteries have allowed calculation of differences in the proportion of shunted blood flowing in these arteries and demonstrate that retrograde movement of blood in the aortic arch may occur.

Studies on the Spread of Excitation through the Ventricular Myocardium II. The Ventricular Septum

The spread of the excitatory process in the ventricular septum of the dogs heart has been studied in the isolated organ perfused by the Langendorff technic. It has been possible to remove large portions of the free wall of the right and left ventricles and explore the septal surfaces under direct vision. The mean excitatory pathway in the muscular mass of the dogs ventricular septum has been demonstrated to be from apex to base. The left side of the septum is activated before the right side, and the apical part of the right side is activated before its base.

Coronary arteriographic findings in patients with axis shifts or S-T-segment elevations on exercise-stress testing

Abstract The exercise ECGs and coronary arteriograms of 158 patients were examined to evaluate the relationship of exercise-induced axis shifts and S-T-segment elevations to coronary artery disease. Eighteen of the 158 patients had exercise-induced S-T-segment elevations. Seventeen of these 18 patients had severe obstruction of the major coronary artery most compatible with the zone of ischemic localization. This obstruction was greater than 85 per cent in 16 patients and greater than 50 per cent in a seventeenth patient. The remaining patient had a normal coronary arteriogram and the most minimal exercise-induced S-T-segment elevations. Nine of the 158 patients had exercise-induced right axis shifts. Only 4 of these 9 patients had greater than 50 per cent obstruction of a major coronary artery, as compared to 103 of 154 patients in the total group studied. Also, there was no trend toward predominant involvement of any particular coronary artery in these 4 patients. Hence, it appears that this finding is not predictably associated with severe localized coronary artery disease. Only 4 of the 158 patients had exercise-induced left axis shifts. Three of these four patients had complete obstruction of the left anterior descending artery. But the group size was small, and the fourth patient had a normal coronary arteriogram. Hence, it is only possible to suggest that this finding may be associated with severe disease of the left anterior descending artery. The results of coronary artery surgery are discussed in a patient who had both a left axis shift and precordial S-T-segment elevations on his preoperative exercise ECG.

Effect of Oxygen on Pulmonary Vascular Resistance in Patients with Pulmonary Hypertension Associated with Atrial Septal Defect

The present studies are concerned with the effect of high oxygen inhalation on patients with atrial septal defects. The problem of the amount of pulmonary vascular resistance and the relative contribution of irreversible structural changes and vascular tone may be of important prognostic significance in evaluation of such patients for cardiac surgery.

Pulmonary Vascular Resistance after Repair of Atrial Septal Defects in Patients with Pulmonary Hypertension

THE BEHAVIOR of the pulmionary vascular bed in congenital heart disease is a topic of major current initerest.1 3 The control of normal pulmoiary vessels remainis a matter for debate, in part because of difficulty in measurements and in the interpretation of the smnall differences in pressure across the normal pulmoniary vascular bed. Inl the presence of pulmioniary hypertenision, however, the responses of the pulmoniary vessels nmay be assessed with greater eertainty, since sizable pressure gradients frequenitly exist. Although a pulmonary arterial systolic pressure in excess of 30 iimm. Hg is outside the norinal range in this laboratory, the categorization of all patients with septal defects and pressures above this level as havinig pulmonary hypertension is of questionable value. Accordingly, we have adopted a pullnonlarv arterial systolic pressure of 60 mm. Hg as the most suitable compromise above which patients may be said to have significant pulmonary hypertension. Such a division serves to separate most patients with congenital heart disease in whom increased pulmonary arterial pressure contributes significantly to the totai problem from those in whom it does not. Classificationi on the basis of pulinonary vaseular resistance reimains the most important conceptual differentiation but suffers from the use of values that are indirect and open to far greater error than is the simple measurement of pulmonary arterial pressure. In atrial septal defects associated with pulmonary hypertension as just defined, the pulmonary vascular resistanee usually is in-