The 125th anniversary of the His bundle discovery.

In 1893, Wilhelm His Jr. was the first to describe the AV (atrioventricular) bundle of the vertebrate heart, which now bears his name. Moreover, prior to the turn of the century, W. His Jr. had proved the function of the AV bundle by transection experiments in animals, and had interpreted Adams Stokes disease as heart block due to pathological changes within the bundle. In this way, he was ahead of his time. While clinical interest was limited to the bundle as the location of an AV block in the first half of the 125 years, it has gained attractiveness since then as a target of diagnostic and therapeutic procedures. The introduction of His bundle electrography relaunched the interest in cardiac arrhythmias. Once the AV bundle could be localized clinically, its ablation, and in recent times its permanent stimulation, became options in the therapy of well-defined arrhythmia and conduction problems.

[Wenckebach and his rhythm]. / Wenckebach en zijn ritme.

Karel Frederik Wenckebach (1864-1940) showed an aptitude for research even as a medical student in Utrecht. After graduation and a thesis on the bursa of Fabricius he worked as an assistant in the physiological laboratory. Following a stint as general practitioner in a mining community (1891-1896) he returned to Utrecht, where he could combine his practice with physiological studies, especially disturbances of the heart rhythm. In 1899, with no other recording instruments than a sphygmomanometer for tracing the radial pulse and a tuning fork for chronometry, he described the 'rhythmic arrhythmia' phenomenon: a missed beat after a given number of regular beats (mostly between three and six), followed by an intermission shorter than the interval between two regular beats. The Wenckebach rhythm is now also known as type I second-degree atrioventricular block. Wenckebach subsequently became a professor of medicine in Groningen (1901), Strasbourg (1911) and Vienna (1914-1929).

Aubrey Leatham and the introduction of cardiac pacing to the UK.

In the early 1950s, Dr Aubrey Leatham established a cardiac unit at St. George's Hospital, Hyde Park Corner, London. He developed and taught the essential clinical skill of cardiac auscultation. Under his guidance a clinical department for the care of cardiac patients was developed and coupled to physiological academic research. He was a pioneer in cardiac pacing and, in 1961, Harold Siddons, O'Neal Humphries, and Aubrey Leatham implanted the first 'indwelling' pacemaker in the UK in a 65-year-old man with repeated Stokes-Adams attacks due to complete heart block. The nickel-cadmium 'accumulator', which powered the pacemaker, had to be recharged once a week.

Woldemar Mobitz and His 1924 classification of second-degree atrioventricular block.

Woldemar Mobitz, an early 20th century German internist, analyzed arrhythmias by graphing the relationship of changing atrial rates and premature beats to AV conduction. Through an astute mathematical approach, he was able to classify second-degree atrioventricular block into 2 types, subsequently referred to as Mobitz type I (Wenckebach) and Mobitz type II (Hay). Type I AV block was most often due to digitalis and was reversible. There were no associated pathological findings. Type II AV block frequently progressed to complete AV block and was associated with seizures, death, and pathological findings.

Walter Gaskell and the understanding of atrioventricular conduction and block.

Walter Holbrook Gaskell was a nineteenth-century British physiologist whose investigations from 1874 until 1889 became central to our current understanding of cardiac physiology. His many cardiac contributions include the following: 1) the recognition of certain inherent properties of cardiac muscle; 2) the experimental proof that led to the acceptance of the myogenic theory of the origin of the heartbeat; 3) the mapping of the anatomy of the sympathetic nervous system; 4) the understanding of the dual autonomic control of the heart; 5) the discovery of the vasodilating effect of sympathetic stimulation on blood flow through skeletal muscle arteries; and 6) the introduction of the concept of heart block. Gaskell's elucidation of the sequence of cardiac contraction and atrioventricular block and his concepts of rhythmicity, excitability, contractility, conductivity and tonicity provided the physiologic explanation necessary for the future understanding of cardiac rhythm disturbances.

Alfred Lewis Galabin and the first human documentation of atrioventricular block.

Using an apexcardiogram, Galabin was the first person to document atrioventricular (AV) block in humans. He performed his studies while working as a house officer at Guy's Hospital, London, United Kingdom. His patient was 34 years old, experienced attacks of near syncope, and had a pulse rate that varied between 25 and 30 beats/min. A laddergram of the patient's apexcardiogram suggests advanced AV block with 3 to 1 and 2 to 1 AV conduction with Wenckebach periodicity. We review the history of AV block beginning with the introduction of graphic recordings in 1847 by Ludwig, and include the contributions of Stannius, Luciani, Gaskell, Wenckebach, Hay, and Mobitz. Although he is little known today among cardiovascular physicians, we recognize Galabin as the first person to demonstrate AV block in humans.

Luigi Luciani and the earliest graphic demonstration of Wenckebach periodicity.

Using an isolated frog heart preparation with ligatures around the atria, Luigi Luciani, an Italian physiologist working in 1873 in Carl Ludwig's famous laboratory in Leipzig, was the first to demonstrate cardiac group beating, which he named periodic rhythm. He attributed this to increased resistance to impulse propagation between the atria and the ventricle. Karel F. Wenckebach, in his 1899 landmark report of group beating in a patient in which he also used pulse tracings, credited Luciani with this discovery. Wenckebach referred to the phenomena as "Luciani periods." With the advent of electrocardiography in the early 20th century, this form of group beating became known as Wenckebach periodicity and then as Mobitz type I atrioventricular block. We reanalyzed Luciani's original paper and pulse tracings, and we show that periodic rhythm does indeed meet the criteria of second-degree atrioventricular block as established by Wenckebach. We also reviewed the career of Luciani, who was an important investigator, outstanding teacher and mentor, and distinguished leader of 19th-century physiology. We conclude that Wenckebach still deserves to have his name eponymously attached to this type of atrioventricular block because he was the first to unravel the complicated relationship between atrial and ventricular conduction.

The Wenckebach phenomenon: a salute and comment on the centennial of its original description.

In 1899, Karel F. Wenckebach unraveled the complicated arrhythmia that bears his name--one of the most famous eponyms in medicine. He reported his findings before the benefit of clinical electrocardiography or the discovery of the sinoatrial and atrioventricular nodes. Born and educated in The Netherlands, Wenckebach first worked in Utrecht in the physiology laboratory of T.W. Engelmann, his respected mentor, where he became familiar with kymographic recordings and rhythm disturbances in frog experiments. He then entered country practice in 1891, where he gained great respect for practicing physicians as well as the importance of clinical experience. In 1896, he returned to Utrecht to work again in the laboratory with Engelmann. In 1898, a woman consulted Wenckebach about her irregular pulse. His investigation of her irregular heart action by using radial arterial pulse tracings and experimental atrial and ventricular pulse tracings from the heart of a frog enabled him to discover the mechanism of partial heart block. In later years, he continued to be a leader in academic medicine, chairing the departments of medicine in Groningen, Strasbourg, and Vienna. He achieved fame for investigating cardiac arrhythmias and other contributions and is considered to be one of the founders of modern cardiology. He is remembered for his insight into atrioventricular conduction, which is as valid today as it was a century ago.