Book Review

ACCELERATED CONDUCTION. THE WOLFF-PARKINSON-WHITE SYNDROME AND RELATED CON- DITIONS. By Prinzmetal, M., Kennamer, R., Corday, E., Osborne, J. A., Fields, J., and Smith, L. A. New York, 1952, Grune & Stratton, Inc., 110 pages, 48 figures.

The principal merit of this monograph is the abundant experimental material which the authors present. The tracings obtained for short P-R interval and aberrant ventricular responses are satisfactory and it is well to consider them as characteristic of Wolff-Parkinson-White syn- drome.

The theoretical discussion is good, although many essential points are overlooked. The authors do not discuss the theory of one or several ectopic foci in relation to electrotonic

variations which originate in the auricle. All the experimental facts given by them are in agree- ment with this theory. The flow of direct noninterrupted currents of subthreshold intensity in the nodal regions produces important changes in the excitability of the adjoining tissues. These changes in the excitability may or may not be related to the “excitatory local process” described by Hodgkin. If the excitability increases, as happens after cathode current is applied, the elec- trotonic variations originated in the auricles may set up a focus in the nodal region or in the ventricles.

The effect produced by applying an electric current of subthreshold intensity is very similar to the effect caused by the current generated by a polarized surface at the boundary of active and resting muscle in the auricle even if the activation wave has not arrived at the node. Never- theless, the latter develops an ectopic focus more easily since the density of the current is increas- ing from monent to moment. During all the time before the activation wave arrives at the node, into this structure will flow a current of subthreshold intensity originated in the auricle (elec- trotonic variation). With this theory it is not necessary to give explanations which look compli- cated.

After a lesion is produced in the bundle of His with the thermocautery, there is no doubt that, in the injured region and in the surrounding area, there is a diminution in conductivity, in the action potential, in the excitability and in the electrotonic variations, which easily explain why the Wolff-Parkinson-White syndrome does not develop.

The authors state that certain experiments conducted recently in their laboratory indicate that specific areas of the ventricles can be blocked by interrupting the branch of the bundle !supplying them. The results obtained in another laboratory, by producing incomplete or com- Iplete block of the right or left branch, do not support this idea.

Neither is it correct to say that after premature activation of a limited area in the ventricle the activation in the rest of the heart is normal. The authors did not study the sequence of activation of the ventricles in their experimental cases of Wolff-Parkinson-White syndrome. In clinical electrocardiography, the precordial, epicardial, and intracavity tracings strongly sug- gest marked modifications in the process of activation during all the electrical systole and not only in the first part.

The aberrant ventricular responses which exist in cases with auricular fibrillation are more easily explained by incomplete block of the left bundle branch. It should be appreciated that in cases with incomplete left bundle branch block, produced by tapping with a probe the place where the branch begins to descend, there is an initial slurring very similar to that seen in Wolff-Parkin- son-white syndrome. Recently in our laboratory, using intraseptal leads, it has been possible tea understand the mechanism of this slurring.

I could discuss many other parts of the book, but I have limited myself to what I consider tihe most important. Notwithstanding these different points of view, the experiments related by the authors are good and the book should be read carefully by all of those interested in electro- cardiographic problems. I wish that the authors had not published a book but instead that they had published an article since it is not possible to accept the main conclusions without further investigation.

D. S. P. 481