| Abstrakt: |
Wilson, Wishart, and Herrmann1have called attention to the laws which govern the flow of currents in solid conductors and to the fact that these laws determine the distribution of the potential differences produced by the heart beat within the body and at its surface, and have pointed out that leads in which one electrode is placed close to the heart and the other at a distance from it are semi-direct leads.In experiments now in progress, it has been found that semi-intrinsic or intrinsicoid deflections may be obtained from the ventricles of the dog when the heart is covered by a pad of gauze, 11/2 to 2 cm. thick, soaked in normal saline solution. Compared with true intrinsic deflections, these deflections are smaller in amplitude and less steep when the recording instrument is used at the same sensitivity. Intrinsicoid deflections can also be obtained from the ventricular cavities by a blood contact. In the case of the auricles, intrinsicoid deflections cannot be obtained either through gauze of the thickness mentioned or from the auricular cavities. It is found that true intrinsic deflections from these chambers are rapidly degraded by increasing the size of the exploring electrode.The difference between auricles and ventricles is due, so it is suggested, to the difference in the manner in which the excitation process spreads over the ventricular as compared with the auricular muscle.When right bundle branch block is produced in dogs the intrinsicoid deflections obtained over the right ventricle are late; those obtained over the left ventricle are early. In left branch block the reverse is the case.In man intrinsicoid deflections can be obtained by placing the exploring electrode upon the precordium. |
