The Dynamic Exercise Electrocardiogram*

Abstract

ISTRODUCTIONSince our previous report, more than 300 electrocardiograms have been obtained on patients performing vigorous exercise (1). The purpose of this communication is to describe the method in detail, indicate the trend of normal variations, and discuss some of the findings in patients with abnormalities of the cardiovascular system.Prior efforts a t recording electrocardiograms during exercise have been only partially successful, since the resultant tracings have contained artifacts inherent in the system used (2-4). The two major difficulties that have been overcome in recording the electrocardiogram during exercise are skeletal muscle potentials and baseline shifts ( Fig. I ) . Skeletal muscle artifacts have been eliminated by attaching the electrodes to areas of the body which are virtually free of skeletal muscles; baseline shifts can be avoided by proper fixation of the electrodes to the skin. Because of the location of the electrodes, the technic is referred to as the Ear-Ensiform-Precordial (EEP) system.A. Apparatus (Fig. 2) nected to a plug jack.' (Fig. 2b.) within a rubber tube 1 cm. thick and 1 cm. in diameter connected to a plug jack. (Fig. 2c.) TECHNIC 1. Ear-lobe electrode consisting of a square (2 x 2 cm.) of stainless-steel wire mesh con-2. Chest electrodes consisting of a piece (1 cm. in diameter) of stainless-steel wire mesh 3. Electrode compound.* 4. Foam rubber cushions, 2 x 3 x 5 cm. (Fig. 2a.) 5 . Chest straps.B. The EEP method (Fig. 3 ) 1. The electrode is secured to the right ear lobe by adhesive tape and a paper clip. 2. The chest electrodes are filled over the brim with electrode compound and placed over the ensiform process, over the fifth rib in the V-3 position, the sixth rib in the V-5 position, a n d the seventh rib in the V-7 position. Each cup electrode is held in place by a "Band-aid" tape and a foam rubber cushion. The foam rubber cushions are held in place over the electrodes by tightly wound elastic chest straps.3. The cables for the patient are attached as follows: a ) With a four-channel machine (Figs. 4, 5 and 6)-the right arm cable to the right ear electrode; the left arm cable to the ensiform electrode; the left leg cable to the V-7 electrode; precordial cables to V-3 and V-5 .electrodes; ground cable to the right arm. b) With a single channel machine, the attachments are the same except that the left leg cable is attached to the V-5 electrode and the single precordial cable to the V-3 electrode.

Continuous Electrocardiographic Recording During Exercise: Its Use in Evaluating the Effect of Pentaerythritol Tetranitrate

“…The electrocardiographic modifications previously described and used in the present evaluation did not, we feel, significantly alter the quality of tracings obtainable with this procedure.7, 8 However, since the modifications provided for somewhat better electrode-to-skin connections, less direct &dquo;drag&dquo; on lead cables and less inconvenience to the patient, they represent useful refinements to the basic procedure.…”

“…DISCUSSION To date, our experiences with the procedure described herein for continuously recording the electrocardiogram during exercise are in agreement with those reported by Freiman and associates. 8 Namely, that this technique furnishes electrocardiographic tracings during exercise that are essentially free of base line shift and interference from muscle potentials. The value of this method over the standard one appears to be threefold: (1) it is safer, in that exercise can be stopped at the first sign of myocardial ischemia or abnormal cardiac rhythm; (2) it provides greater information with which to evaluate early or occult atherosclerotic heart disease, since it permits monitoring RS-T segment changes that occur during exercise, but which may be completely absent in the immediate postexercise period; (3) as the results of this evaluation indicate, it can be used to determine more accurately and quantitatively the effect of therapeutic measures on exercise-induced changes in the electrocardiogram.…”

“…8 In this procedure, the chest electrodes are placed over the ensiform process, over the 5th rib in the V-3 position, over the 6th rib in the V-5 position, and over the 7th rib in the V-7 position. The foam rubber shields encasing the electrodes are held in place with chest straps, and electrode-to-skin contact is facilitated by using standard electrode paste.…”