The precordial electrocardiogram

Electrocardiograms of forty-six cases of pure pulmonary stenosis were analyzed before and after valvulotomy. The electrocardiograms taken at the last postoperative examinations (three months or longer after the operation) revealed significant changes as compared with the preoperative tracings. It is suggested that these changes may be due to the diminished load on the right ventricle and'-ight auricle after the operation. Evidence is presented that electrocardiography offers a simple and valuable means for the evaluation of the result of valvulotomy in pure pulmonary stenosis.

Section: Discussionsupporting

confidence: 44%

Postoperative Changes in the Electrocardiogram in Congenital Heart Disease

Landtman

1954

“…The electrocardiographic position of the heart in the chest was determinedl according to the method of Wilson and his coworkers. 4 The corrected Q-T interval was determined, using a modified Bazette formula as described by Taran cardiographic position of the heart in the chest before and after the race was determined: In 94.3 per cent the position was semivertical or vertical before and after the race. In 5.7 per cent the position was intermediate before and after the race.…”

Section: Methodsmentioning

confidence: 99%

Cardiovascular Adaptations to Prolonged Physical Effort

Beckner

Winsor

1954

Studies of the cardiovascular system were made among 26-mile marathon runners after at least five yearms of physical training. Studies made with the subjects at rest showed an electrocardiogram characterized by a vertical or semivertical electrocardiographic position of the heart in the chest, bradycardia, high voltage of the QRS complexes and high T and U waves. T waves which were low with respect to the height of the R waves were not encountered. Etiologically the heart was enlarged. Immediately after running 26 miles the transverse diameter of the heart was decreased considerably.

“…Accordingly, the direction of the mean QRS vector in the normal subject and in the subject with left ventricular hypertrophy depends principally upon the characteristics of epicardial depolarization of the left ventricle. There are two factors which determine these characteristics: (1) The conduction system, that is the sequence in which the excitation process is distributed to the various regions of the left ventricle, and (2) the thickness of the wall of the left ventricle, for it takes approximately 10 times longer for excitation to traverse the wall thans to spread an equal distance along the conduction pathways of the endocardium.…”

Section: Discussionmentioning

confidence: 99%

The Relationship between the Anatomic Position of the Heart and the Electrocardiogram

Grant

1953

Using a method for identifying precisely the lie of the ventricular structures in the body at autopsy, the anatomic position of the heart was compared with the directions of the QRS electrical forces in a large number of subjects with and without heart disease. While the mean QRS axis varied through 180 degrees in these subjects, the anatomic position of the left ventricle varied less than 45 degrees. No instances of significant rotation of the heart around its long axis were encountered, and it is shown that the unipolar electrocardiographic criteria for position and rotation of the heart have little validity. An explanation for the axis deviations of ventricular hypertrophy is offered.