In 1899 he provided a description of irregular pulses due to partial blockage of atrioventricular conduction, creating a progressive lengthening of conduction time in cardiac tissue.

[2] Wenckebach was an early advocate involving the use of quinine for treatment of paroxysmal atrial fibrillation.

His father Eduard (1813–1874) has been credited with developing the very first telegraphic communications line in the Netherlands, between Haarlem and Amsterdam.

He had two brothers, Henri Johan Eduard (1861–1924), director of the State Mines and later of the Dutch Ironworks in IJmuiden, and Ludwig Willem Reymert (1860–1937), a well-known painter and book illustrator.

His son Oswald became a sculptor, painter and medallist, most widely known for his war monuments and designing the Dutch coins issued between 1948 and 1981.