[The centennial of the Einthoven electrocardiograph. Part I]

The initial studies about the "irritability" of animal tissues by iatrophysic or iatromechanic scientists are reviewed. These studies led to discover the so called animal electricity envisaged by Luigi Galvani in the XVIII century and demonstrated by Carlo Matteucci and his followers in the XIX. Beginning with the Galvani's "reoscopic" frog, which allowed to assess the electrical current in a qualitative sense, it was possible to arrive, at the beginnings of the XX century, to the string electrocardiograph developed by Willem Einthoven in 1901. This opened the way that led to fabrication of ever more sophisticated instruments until the present systems of endocardial mapping by magnetic technology or by multipolar catheters, which permit to quickly identify the site of origin or the spreading ways of a tachycardia for their ablation with radiofrequency. Intracardiac echocardiography is also employed to define the anatomy of right atrium, during intracardiac cartography, in order to establish the most adequate sites for ablation. On the other hand, a logic, i.e. rational, method for the interpretation of results from the electrical exploration of the heart has been developed. This one was introduced by Frank N. Wilson in Ann Arbor and has been fittingly applied by Demetrio Sodi Pallares in Mexico. Important diagnostic advances and notable therapeutic inferences have been derived from these latter developments.

The remote past and near future of electrocardiology: view-point of a biomedical engineer

The major steps of advancement in electrocardiology over a period exceeding one century of its existence are briefly summarized, and some considerations concerning the most promising trends of its current and future progress are presented. (Tab. 2, Fig. 2, Ref. 39.)

Sunao Tawara: a father of modern cardiology

Knowledge of the conduction system of the heart was greatly advanced by Tawara's work carried out in Aschoff's laboratory in Marburg at the beginning of this century. In his monograph, The Conduction System of the Mammalian Heart, published in 1906, Tawara indicated that the treelike structure of specific muscle fibers comprising the atrioventricular node, His bundle, bundle branches, and Purkinje fibers served as the pathway for atrioventricular conduction of excitation in the mammalian heart. From his own anatomic and histological findings of the conduction system, he assumed precisely that the conduction velocity of excitation in the system, except in the atrioventricular node, would be fast and that contraction as the result of excitation would take place at the various sites of the ventricles almost simultaneously. According to Tawara, a long pathway to each contracting unit and a fast conduction velocity of excitation would be a prerequisite for the effective contraction of the ventricles. Tawara's findings and assumptions provided Einthoven the theoretical basis for interpreting the electrocardiogram, resulting in rapid popularization of electrocardiography. This century has witnessed the rapid progress of cardiology, including cardiac pacing and its related sciences. This progress has its roots in the discovery of the conduction system and the development of electrocardiography that took place almost in the same period at the beginning of this century. Tawara's pioneering work on the conduction system still serves as an invaluable reference for basic and clinical research.

Centennial of the string galvanometer and the electrocardiogram

This article is a review of the history of the string galvanometer and of the electrocardiogram (ECG) on the occasion of the centennial of the instrument. Einthoven most likely developed the string galvanometer prior to 1901, the date of the first publication. The galvanometer made electrocardiography practical creating a new branch of medicine and even a new industry. In 1791 Galvani, in 1842 Mateucci and in 1855 Kolliker and Muller recorded, using the nerve muscle preparation, contraction of injured muscle, contraction of muscle when laid across a beating heart, and occasionally two contractions. In 1872 Lippmann introduced the capillary manometer. Using the capillary manometer Waller recorded for the first time from body surface voltage changes generated by the heart. Einthoven and Lewis dominated the early years of electrocardiography. The former made his contributions by 1913 while Lewis continued the studies of arrhythmias until 1920. The period following 1920 was influenced largely by Wilson. None did as much to advance ECG knowledge as did Wilson. The interest shifted to the theory of the ECG, abnormalities of wave form and of ECG leads. A major contribution of the ECG is in evaluation of ischemic heart disease and cardiac arrhythmias. Issues facing electrocardiography in the year 2000 include a shortage of experienced electrocardiographers, the advent of new noninvasive procedures and, paradoxically, wide acceptance of the ECG by the medical profession. The role of the computer in analysis of the clinical ECG is limited. The technique, while reasonably reliable for analysis of the normal tracing and some ECG waveforms, has serious limitations when applied to arrhythmias. The early hopes for "stand-alone" programs are yet to be realized.

Evolution of diagnostic and interventional cardiac electrophysiology: a brief historical review

The field of clinical cardiac electrophysiology has evolved dramatically over the last 30 years, beginning with description of the first His bundle recording in 1969. Subsequently, in the early 1970s, more sophisticated diagnostic electrophysiologic techniques were developed to diagnose and guide drug treatment of arrhythmias. These diagnostic techniques were further advanced during the late 1970s and 1980s to electrically map arrhythmias and guide their surgical ablation. Surgical treatments of both supraventricular and ventricular arrhythmias proliferated in the 1970s and 1980s, with overall excellent results. However, because of the morbidity and mortality associated with arrhythmia surgery, it was ultimately replaced in the 1990s by radiofrequency catheter ablation (RFCA) for treatment of most forms of supraventricular tachycardia and idiopathic ventricular tachycardia, and by the automatic implantable cardioverter defibrillator (ICD) for treatment of life-threatening ventricular arrhythmias associated with coronary artery disease and dilated cardiomyopathy. At present, the only arrhythmias that cannot be reliably and safely cured by RFCA are chronic atrial fibrillation and life-threatening ventricular arrhythmias. For chronic atrial fibrillation, new catheter designs are being developed to create linear ablation lines mimicking the curative MAZE operation. For life-threatening ventricular arrhythmias, the ICD has been increasingly utilized as transvenous lead systems and smaller devices have been developed. In the next millennium, new developments that may be expected for treatment of atrial fibrillation and life-threatening ventricular arrhythmias include catheter systems for linear RFCA of atrial fibrillation, ICDs for both atrial and ventricular defibrillation, and biventricular pacing ICDs for patients with congestive heart failure.

[A historical review of the study of electrical activity of heart and origination of electrocardiography]

This paper has an overall review of the historical process of electrocardiographic development and the origination of modern electrocardiography in retrospect and also has an analysis of the scientific background, the important events and the historical effect of outstanding figures throughout the development. The experience and laws contained in the historical development are briefly summerized in this paper. At the same time the authors point out that the establishment of modern electrocardiography and the related technical development are crystallization of the wisdom and the result of the hard work of many scientists including the figures who should have been awarded Nobel Prizes.

The evolution of internal defibrillators

ICDs have reduced mortality from SCD to 2% per year, which is a record unmatched by any other form of therapy. With continued evolution, ICD systems should become easier to implant, smaller, more effective in managing a variety of abnormal rhythms, and more comfortable for the patient. Implementation of technological innovations in future-generation devices should continue to extend the frontiers as clinicians consider ICDs for an expanding range of therapeutic applications.