The triangular wave test for electrocardiographic devices: a historical perspective

Baseline wander makes interpretation ECG recordings difficult, especially the assessment of ST deviation. Eliminating baseline wander without distorting the ST segment is a problem. The traditional high pass filter with a 0.5 Hz low frequency cutoff effectively suppresses baseline but introduces considerable distortion in the level of the ST segment. This distortion results from phase nonlinearities that occur when frequency content and wave amplitude change abruptly, as occurs where the end of the QRS complex meets the ST segment. Since the 1980s nonlinear, digital filters have been designed that can increase the low frequency cutoff without the introduction of phase distortion. The triangular wave test, first described in the 1990 AHA Recommendations, is an objective method for measuring the ability to suppress baseline wander without affecting the ST segment. This methodology was adopted in 3 American National Standards.

The Earliest Published Electrocardiogram Showing Ventricular Preexcitation

When in 1930, Wolff, Parkinson, and White published what is today known as the WPW, or preexcitation syndrome, they, and subsequently others, found few comparable cases in the preceding literature. Among these the report of Cohn and Fraser, published in 1913, was the earliest. However, another even earlier documentation in a 1909 article by Hoffmann escaped notice till now. The ECG of a patient with paroxysmal tachycardia reveals a short PR interval and a delta-wave-induced widening of the QRS complex, even though the reproduced tachycardia was not preexcitation related. The interpretation of this poorly reproduced ECG can be confirmed by another and more detailed description of the patient in an electrocardiography textbook published in 1914 by the same author. Thus, the earliest publication of an ECG showing ventricular preexcitation now can be dated back to 1909. Moreover, the Hoffmann monograph contains two additional examples of the WPW syndrome not noticed until now. All three cases published by Hoffmann had their first ECG recordings in 1912 or earlier.

[The German physician and pacifist Georg Friedrich Nicolai (1874-1964) as a pupil of the Russian physiologist Ivan Petrovic Pavlov (1849-1936)]

In 1906, Dr. med. Georg Friedrich Nicolai, a young specialist in the field of electrocardiography from the university of Berlin, spent some months in the laboratory of Pavlov, where he was one of the first German visitors. Two letters written by Nicolai to Pavlov are a mirror of Nicolai's admiration for the brilliant Russian Nobel prize winner, but also of Nicolai's remarkable insight into the perspectives of Pavlov's physiological method for "objective" psychological investigations. Nicolai regarded himself a pupil of Pavlov until his death in South America, where he was forced to emigrate after World War I due to his pacifist activities.

The ligation of coronary arteries with electrocardiographic study. 1918

This article is based on a study of sixty-six dogs in which known myocardial lesions had been produced by the ligation of definite branches of the coronary arteries of the heart. While the experiments were made with the primary object of determining the change in the electrocardiograms brought about by these ligations, other results, anatomic and pathologic, are deemed worthy of brief mention.

[The history of a detail--a study of ST-elevation in ECG]

ST-elevation in EKG is an important diagnostic sign of acute myocardial infarction since more than 80 years. Important clinical decisions such as hospitalisation for intensive coronary care and reperfusion of the occluded coronary artery by means of thrombolytic drugs or catheter intervention depend on this sign. A rapid resolution of a ST-elevation during these therapeutic procedures reflects successful reperfusion of the infarct-related coronary artery. The definition of ST-elevation is sometimes problematic. Availability of the patient's previous EKG from a database facilitates evaluation of ST-elevations.

The Ashman phenomenon

In the presence of atrial fibrillation, impulses of supraventricular origin that are transmitted through the ventricles during periods of relative refractoriness to impulse conduction exhibit anomalous configurations. These "aberrant beats" can be difficult to distinguish from ventricular ectopic beats, and groups of aberrant beats may be mistaken for ventricular tachycardia. Richard Ashman, PhD, a physiologist at Louisiana State University School of Medicine in New Orleans, noted that ventricular refractoriness varied with the lengths of cardiac cycles; that aberrant beats typically ended short cycles following long cycles; and that aberrant beats often have a right bundle branch block configuration. This observation, known as the "Ashman phenomenon," has become a principle of cardiology. Its recognition may allow clinicians to distinguish aberrant beats from ventricular ectopy. Ashman made a variety of other fundamental contributions to electrocardiography and was also an accomplished poet.

Intracardiac electrocardiography via a “saline-filled central venous catheter electrocardiographic lead”: a historical perspective

The author describes his experience with a "saline-filled central venous catheter electrocardiographic lead" for the recording of intracardiac electrocardiograms provides a brief description of the methodology, refers to this modality's clinical usefulness, furnishes 2 examples illustrating the contribution of the method to clinical diagnosis, and outlines his literature search to find the discoverer/originator of the employment of a saline-filled intracardiac catheter as an electrocardiogram recording lead.

[Einthoven: the man and his invention]

Einthoven, a Dutch physician, was awarded the Nobel Prize for Physiology or Medicine for his discovery of the mechanism of the electrocardiogram. He was born on May 21, 1860, in Semarang, on the island of Java. In 1878 entered the University of Utrecht in The Netherlands, as a medical student, where he also became a keen sportsman. In 1885, he was appointed Professor of Physiology at the University of Leiden, where he began to work using first a capillary electrometer. Later, Einthoven invented a new galvanometer to generate electrocardiograms using a fine quartz string coated in silver and published his findings in 1901 and 1903. Einthoven is remembered by most of his colleagues and clinical peers as a very modest person who was hospitable and honest. He died at the age of sixty seven.

[The historical bases of a super-specialty: electrocardiography]

In the XVIII century the first structured experiments in the field of bioelectricity were performed, and the Italian scientist Luigi Galvani documented the muscular contraction of a frog undergoing an electric shock. In 1791 he showed that the electric stimulation of the heart of a frog determined the contraction of the heart itself. In the first thirty years of the XIX century galvanometers were developed, and in 1842-42 Carlo Matteucci documented that electric activity was present even in the cardiac muscle at rest. At the end of the XIX century Augustus Waller was among the first scientists to publish an electrocardiographic recording obtained from the human body surface; most of his contemporaneous, however, did not retain that electrocardiography might have been an effective clinical application. Willem Einthoven, instead, was convinced of the widespread feasibility of clinical electrocardiography, and promoted a number of improvements and refinements in electrocardiographic technique. The most important and diagnostic-technical development of electrocardiography occurred in the second half of the XX century, and still today, even if many different sophisticated instrumental examinations are available for cardiologic evaluation, electrocardiography represents an essential first-line diagnostic tool in clinical cardiology.