Effect on Electrocardiogram of Opening Thorax and Inserting Optical Manometers into Aorta and Pulmonary Artery.

Abstract

Recently Weinmann and Katz 1 investigated the relation of the T wave to the asynchronous ending of right and left systole. To do this the chest was opened and optical manometers were inserted into the aorta and pulmonary artery. The objection might be raised that such procedures are sufficiently abnormal to make the electrocardiogram noticeably different, and therefore not comparable with the normal. The present report deals with the effect of such procedures on the electrocardiogram.

Meek and Wilson 2 made a comparison of the electrocardiogram in the open and closed chested dog and came to the following conclusions: “Electrocardiograms from animals with an open chest are also usually normal. By this we mean that the waves are all apparent and of the usual form. Only two variations are common. R3 is often notched and the T wave is apt to be negative or diphasic, conditions which may appear in the dog under almost any operative procedure.” The present investigation substantiates these facts in general, although differing in some of the details.

In 7 dogs the standard electrocardiograms, Leads I, II and III, taken with the animal on its back under morphine and chloretone anesthesia, were compared with these three identical leads obtained after the chest was opened. A typical set of records is shown in Fig. 1. In a second series of 7 animals similar electrocardiograms,

Leads I, II and III, taken before the chest was opened were compared with those taken after the chest was opened and the manometers inserted into the aorta and pulmonary artery. Fig. 2 shows a typical set of such records.

An inspection of these figures reveals how little the electrocardiograms are changed. The heart rate was increased by these procedures in most cases, as in Figs. 1 and 2, but in others it remained unchanged or even decreased.